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+*** START OF THE PROJECT GUTENBERG EBOOK AN INTRODUCTION TO THE STUDY OF FISHES ***
+
+
+
+
+
+                            AN INTRODUCTION
+
+                                TO THE
+
+                            STUDY OF FISHES
+
+
+                                  BY
+                        ALBERT C. L. G. GÜNTHER
+                        M.A. M.D. Ph.D. F.R.S.
+
+       KEEPER OF THE ZOOLOGICAL DEPARTMENT IN THE BRITISH MUSEUM
+
+
+  [Illustration: Carpit aquas pinnis.]
+
+
+                               EDINBURGH
+                        ADAM AND CHARLES BLACK
+                                 1880
+
+                       [_All rights reserved._]
+
+
+
+
+               _Printed by_ R. & R. CLARK, _Edinburgh_.
+
+
+
+
+                               PREFACE.
+
+
+The scope of the present work is to give in a concise form an account
+of the principal facts relating to the structure, classification, and
+life-history of Fishes. It is intended to meet the requirements of
+those who are desirous of studying the elements of Ichthyology; to
+serve as a book of reference to zoologists generally; and, finally,
+to supply those who, like travellers, have frequent opportunities
+of observing fishes, with a ready means of obtaining information.
+The article on “Ichthyology,” prepared by the late Sir J. Richardson
+for the eighth edition of the “Encyclopædia Britannica,” is the only
+publication which has hitherto partly satisfied such requirements;
+and when I undertook, some years ago, to revise, or rather rewrite
+that article for the new edition of that work, it occurred to me that
+I might at the same time prepare a Handbook of Ichthyology, whilst
+reserving for the article an abstract so condensed as to be adapted for
+the wants of the general reader.
+
+From the general plan of the work I have only departed in those
+chapters which deal with the Geographical Distribution of Fishes. This
+is a subject which has never before been treated in a general and
+comprehensive manner, and seemed to demand particular attention. I
+have, therefore, thought it right to give nominal lists of the Faunæ,
+and the other details of fact on which I have based my conclusions,
+although all the necessary materials may be found in my “Catalogue of
+Fishes.”
+
+A few references only to the numerous sources which were consulted
+on the subjects of Chapters 1–12, are inserted in the text; more not
+required by the beginner; he is introduced to a merely elementary
+knowledge of facts well known to the advanced student.
+
+With regard to the illustrations, about twenty have been prepared after
+originals published by Cuvier, J. Müller, Owen, Traquair, Duméril,
+Cunningham, Hasse, Poey, Siebold, and Gegenbaur. A similar number,
+representing extinct fishes, have been taken, with the kind permission
+of the author, from Owen’s “Palæontology.” My best thanks are due also
+to the Committee of Publications of the Zoological Society, and to the
+Editors of the “Annals and Magazine of Natural History,” and of the
+“Journal des Museum Godeffroy,” for the loan of woodcuts illustrating
+some of my papers on South American fishes and on larval forms. The
+remainder of the illustrations (about three-fourths) are either
+original figures, or formed part of the article on ‘Ichthyology’ in the
+former edition of the “Encyclopædia Britannica.”
+
+   LONDON, _3d October 1880_.
+
+
+
+
+                               CONTENTS.
+
+
+                         INTRODUCTORY REMARKS.
+
+                                                                   PAGE
+
+    FISH DEFINED--ICHTHYOLOGY DEFINED                                 1
+
+
+                              CHAPTER I.
+
+    HISTORY AND LITERATURE                                            2
+
+    Aristotle, 2--Belon, 4--Salviani, 6--Rondelet, 6--Faunists and
+    Anatomists of the Seventeenth Century, 7--Ray and Willughby,
+    8--Artedi, 9--Linnæus, 10--Gronow and Klein, 12--Pupils
+    and Successors of Linnæus, 12--Bloch, 13--Lacépède, 15--Anatomists
+    and Faunists preceding Cuvier, 16--Cuvier, 17--Agassiz,
+    20--J. Müller, 22--Discovery of Ceratodus, 25--Recent
+    publications on Fishes, 26--Latest systematic works, 33.
+
+
+                              CHAPTER II.
+
+    TOPOGRAPHICAL DESCRIPTION OF THE EXTERNAL PARTS OF
+      FISHES                                                         35
+
+    Form of the body, 35--External parts of the head, 36--Trunk and
+    Tail, 39--Fins; their structure, position, and function, 40--Skin
+    and Scales, 45.
+
+
+                             CHAPTER III.
+
+    TERMINOLOGY AND TOPOGRAPHY OF THE SKELETON                       51
+
+    Axial portion, 51--Vertebra and its parts; terms defined,
+    51--Skull; bones topographically enumerated, 53--Bones of the
+    limbs, 59--Synonymic list of bones, 59.
+
+
+                              CHAPTER IV.
+
+    MODIFICATIONS OF THE SKELETON                                    63
+
+    Branchiostoma, 63--Cyclostomes, 64--Chondropterygians,
+    66--Holocephali, 70--Ganoids, 71--Dipnoi, 71--Chondrostei,
+    74--Polypteroidei, 77--Lepidosteoidei, 80--Amioidei,
+    82--Teleostei, 83--Classification of the bones of the
+    Teleosteous skull according to the vertebral doctrine,
+    85--their morphological classification, 86--Limb-bones of
+    Teleosteans, 92.
+
+
+                              CHAPTER V.
+
+    MYOLOGY                                                          93
+
+    General arrangement of the Muscles, 93--Electric organs, 94.
+
+
+                              CHAPTER VI.
+
+    NEUROLOGY                                                        96
+
+    Of Branchiostoma, 96--Spinal chord, 96--Brain, its size, 97--Brain
+    of Osseous fishes, 97--of Ganoids, 98--of Chondropterygians,
+    100--of Cyclostomes, 101--Spino-cerebral nerves, 103--Spinal
+    nerves, 107--Sympathic system, 108.
+
+
+                             CHAPTER VII.
+
+    THE ORGANS OF SENSE                                             109
+
+    Smell, 109--Sight, 111--Hearing; connection of the ear with the
+    air-bladder, 116--Taste, 119--Touch, 120.
+
+
+                             CHAPTER VIII.
+
+    THE ORGANS OF NUTRITION AND DIGESTION                           121
+
+    Food and mode of feeding, 121--Buccal and abdominal cavities and
+    their openings, 123--Mouth and tongue, 123--Forms, texture,
+    and arrangement of teeth, 124--Intestinal tract, 127--Liver,
+    132--Pancreas, 133--Spleen, 133.
+
+
+                              CHAPTER IX.
+
+    ORGANS OF RESPIRATION                                           135
+
+    Respiration, 135--Structure and arrangement of the gills,
+    136--Pseudobranchiæ, 140--Accessory respiratory organs,
+    142--Air-bladder; its varieties, structure, and functions, 142.
+
+
+                              CHAPTER X.
+
+    ORGANS OF CIRCULATION                                           150
+
+
+                              CHAPTER XI.
+
+    URINARY ORGANS                                                  155
+
+
+                             CHAPTER XII.
+
+    ORGANS OF REPRODUCTION                                          157
+
+    Fishes are dioecious, 157--Hermaphroditism, 157--Oviparous and
+    viviparous fishes, 157--Generative organs of Branchiostoma,
+    157--of Cyclostomes; their ova, 158--Female organs of
+    Teleosteans and their ova, 158--Instances of females taking
+    care of their progeny, 160--Male organs of Teleosteans,
+    162--Instances of males taking care of their progeny,
+    163--Generative organs of Ganoids, 163--of Chondropterygians
+    and their ova, 166.
+
+
+                             CHAPTER XIII.
+
+    GROWTH AND VARIATION OF FISHES                                  170
+
+    Changes of form of the body or certain parts, normally accompanying
+    growth, 170--Changes dependent on sexual development,
+    176--Secondary sexual differences, 176--Mixogamous, polygamous,
+    and monogamous fishes, 177--Hybridism as a cause
+    of variation, 178--Regular and irregular growth of fishes,
+    178--Leptocephali not a normal state of development, 179--Changes
+    of colour of the muscles and external parts; chromatophors,
+    182--Albinism, 183.
+
+
+                             CHAPTER XIV.
+
+    DOMESTICATED AND ACCLIMATISED FISHES, ETC.                      185
+
+    Domesticated fishes, 185--Acclimatisation of fishes,
+    185--Artificial impregnation of ova, 186--Tenacity of life,
+    186--Reproduction of lost parts, 188--Hybernation, 188--Useful
+    fishes, 189--Poisonous fishes, 189--Poison-organs, 190.
+
+
+                              CHAPTER XV.
+
+    DISTRIBUTION OF FISHES IN TIME                                  193
+
+    Oldest fish-remains, 193--Devonian fishes, 194--Carboniferous,
+    196--Permian, 197--Triassic, 197--Liassic, 198--Oolitic,
+    199--Cretaceous, 199--Tertiary, 200--Post-pliocene, 201.
+
+
+                             CHAPTER XVI.
+
+    THE DISTRIBUTION OF EXISTING FISHES OVER THE EARTH’S
+      SURFACE.--GENERAL REMARKS                                     202
+
+    Freshwater-, Marine-, and Brackish-water Fishes, 202--Changes of
+    the habitat of numerous fishes, active, 203--or dependent on
+    geological changes, 204--Agencies operating upon the distribution
+    of Freshwater and Marine fishes, 205.
+
+
+                             CHAPTER XVII.
+
+    THE DISTRIBUTION OF FRESHWATER FISHES                           208
+
+    List of Freshwater Fishes, 208--Continuous and interrupted range
+    of distribution, 209--The ways of dispersal of Freshwater
+    fishes, 211--A wide range of a type is not necessarily proof of
+    its antiquity, 212--Each fauna is composed of ancient, autochthont,
+    and immigrant species, 213--Division of the globe
+    into zoological regions; freshwater fishes have been spread in
+    circumpolar zones, 215--Cyprinidæ and Siluridæ, most important
+    families in recognising the zoo-geographical regions,
+    216--Division of the faunæ of Freshwater fishes, 217--I.
+    _Equatorial Zone_, 218--Indian Region, 220--African Region,
+    227--Tropical American or Neotropical Region, 233--Tropical
+    Pacific Region, 238--II. _Northern Zone_, 240--Europe-Asiatic
+    or Palæarctic Region, 243--North American or Nearctic
+    Region, 246--III. _Southern Zone_, with Tasmanian, New
+    Zealand, and Fuegian Sub-regions, 248.
+
+
+                            CHAPTER XVIII.
+
+    THE FISHES OF THE BRACKISH WATER                                251
+
+
+                             CHAPTER XIX.
+
+    THE DISTRIBUTION OF MARINE FISHES                               255
+
+    Shore-fishes, Pelagic, and Deep-sea fishes, 255--List of
+    Shore-fishes, 257--Oceanic areæ as determined by Shore-fishes,
+    259--Distribution of Shore-fishes compared with that of
+    Freshwater-fishes, 260--I. _Arctic Ocean_, 261--II. _Northern
+    Temperate Zone_, 262--Temperate North-Atlantic, 262--with
+    British, 263--Mediterranean, 264--and North American districts,
+    266--Temperate North-Pacific, 268--with Kamtschatkan,
+    269--Japanese, 270--and Californian districts, 271--III.
+    _Equatorial Zone_, 272--with Tropical Atlantic, 278--Indo-Pacific
+    Ocean, 278--and the Pacific Coasts of Tropical America,
+    279--IV. _Southern Temperate Zone_, 281--with the Cape of Good
+    Hope, 283--South Australia and New Zealand, 283--Chile, 288--and
+    Patagonia, 289--V. _Antarctic Ocean_, 289.
+
+
+                              CHAPTER XX.
+
+    DISTRIBUTION OF PELAGIC FISHES                                  292
+
+
+                             CHAPTER XXI.
+
+    THE FISHES OF THE DEEP SEA                                      296
+
+    Deep-sea fishes a recent discovery, 296--Physical conditions affecting
+    these fishes, 297--Characteristics of Deep-sea fishes, 299--Their
+    vertical and horizontal distribution, 304--List of Deep-sea
+    fishes, 305.
+
+
+                   SYSTEMATIC AND DESCRIPTIVE PART.
+
+
+                    FIRST SUB-CLASS--PALÆICHTHYES.
+
+                                                                   PAGE
+    FIRST ORDER--CHONDROPTERYGII                                    313
+
+      I. _Plagiostomata_                                            313
+
+        A. _Selachoidei--Sharks_                                    314
+
+          Families: Carchariidæ (Blue Shark, Tope, Hammerhead,
+          Hound), 316--Lamnidæ (Porbeagle, Carcharodon,
+          Fox-Shark, Basking-Shark), 319--Rhinodontidæ,
+          323--Notidanidæ, 324--Scylliidæ (Dog-fishes),
+          325--Hybodontidæ, 328--Cestraciontidæ (Port Jackson
+          Shark), 328--Spinacidæ (Spiny Dogs, Greenland
+          Shark), 330--Rhinidæ, 334--Pristiophoridæ, 335.
+
+        B. _Batoidei--Rays_                                         335
+
+          Families: Pristidæ (Saw-fishes), 336--Rhinobatidæ,
+          337--Torpedinidæ (Electric Rays), 338--Rajidæ (Rays
+          and Skates), 340--Trygonidæ (Sting Rays), 342--Myliobatidæ
+          (Eagle Rays), 344.
+
+     II. _Holocephala_                                              348
+
+          Family: Chimæridæ, 348.
+
+
+    SECOND ORDER--GANOIDEI                                          350
+
+        I. _Placodermi_                                             351
+
+       II. _Acanthodini_                                            355
+
+      III. _Dipnoi_                                                 355
+
+          Families: Sirenidæ (Lepidosiren, Protopterus, Ceratodus),
+          355--Ctenododipteridæ, 359--Phaneropleuridæ, 360.
+
+       IV. _Chondrostei_                                            360
+
+          Families: Acipenseridæ (Sturgeons), 360--Polyodontidæ,
+          362.
+
+        V. _Polypteroidei_                                          363
+
+          Families: Polypteridæ, 364--Saurodipteridæ,
+          365--Coelacanthidæ, 365--Holoptychidæ, 365.
+
+       VI. _Pycnodontoidei_                                         366
+
+          Families: Pleurolepidæ, 366--Pycnodontidæ, 366.
+
+      VII. _Lepidosteoidei_                                         367
+
+          Families: Lepidosteidæ, 367--Sauridæ, 368--Stylodontidæ,
+          368--Sphærodontidæ, 368--Aspidorhynchidæ,
+          369--Palæoniscidæ, 369--Platysomidæ, 370.
+
+     VIII. _Amioidei_                                               370
+
+           Families: Caturidæ, 371--Leptolepidæ, 371--Amiidæ
+           (Bow-fin), 371.
+
+
+                     SECOND SUB-CLASS--TELEOSTEI.
+
+    FIRST ORDER--ACANTHOPTERYGII                                    374
+
+        I. _A. perciformes_                                         374
+
+          Families: Percidæ (Freshwater-Perches, Bass, Sea-Perches,
+          Centrarchus), 375--Squamipinnes (Coral-Fishes),
+          397--Mullidæ (Red-Mullets), 403--Sparidæ
+          (Sea-breams), 405--Hoplognathidæ, 410--Cirrhitidæ,
+          410--Scorpænidæ, 412--Nandidæ, 418--Polycentridæ,
+          418--Teuthididæ, 418.
+
+       II. _A. beryciformes_                                        419
+
+          Family: Berycidæ, 420.
+
+      III. _A. kurtiformes_                                         424
+
+           Family: Kurtidæ, 424.
+
+       IV. _A. polynemiformes_                                      425
+
+           Family: Polynemidæ, 425.
+
+        V. _A. sciæniformes_                                        426
+
+           Family: Sciænidæ (Meagres), 426.
+
+       VI. _A. xiphiiformes_                                        431
+
+           Family: Xiphiidæ (Sword-fishes), 431.
+
+      VII. _A. trichiuriformes_                                     433
+
+           Families: Trichiuridæ (Scabbard-fishes, Hairtails),
+           433--Palæorhynchidæ, 437.
+
+
+     VIII. _A. cotto-scombriformes_                                 438
+
+          Families: Acronuridæ (Surgeons), 438--Carangidæ
+          (Horse-Mackerels, Pilot-fish, Boar-fish), 440--Cyttidæ
+          (John Dorey), 450--Stromateidæ, 452--Coryphænidæ
+          (Dolphin, Sun-fish), 452--Nomeidæ,
+          455--Scombridæ (Mackerel, Tunny, Bonito, Albacore,
+          Sucking-fish), 456--Trachinidæ (Stare-gazer,
+          Weever, etc.), 462--Malacanthidæ, 467--Batrachidæ,
+          467--Psychrolutidæ, 469--Pediculati (Angler,
+          Antennarius, etc.), 469--Cottidæ (Bull-heads, Gurnards),
+          476--Cataphracti (Flying Gurnards), 480--Pegasidæ,
+          482.
+
+       IX. _A. gobiiformes_                                         483
+
+          Families: Discoboli (Lump-suckers), 483--Gobiidæ
+          (Gobies, Dragonets), 485.
+
+        X. _A. blenniiformes_                                       490
+
+          Families: Cepolidæ (Band-fishes), 490--Trichonotidæ,
+          490--Heterolepidotidæ, 491--Blenniidæ (Wolf-fish,
+          Blennies), 492--Acanthoclinidæ, 498--Mastacembelidæ,
+          499.
+
+       XI. _A. mugiliformes_                                        499
+
+          Families: Sphyrænidæ (Barracudas), 499--Atherinidæ
+          (Atherines), 500--Mugilidæ (Mullets), 501.
+
+      XII. _A. gastrosteiformes_                                    504
+
+          Families: Gastrosteidæ (Sticklebacks), 504--Fistulariidæ
+          (Flute-mouths), 507.
+
+     XIII. _A. centrisciformes_                                     508
+
+          Family: Centriscidæ, 508.
+
+      XIV. _A. gobiesociformes_                                     510
+
+          Family: Gobiesocidæ, 512.
+
+       XV. _A. channiformes_                                        513
+
+          Family: Ophiocephalidæ, 513.
+
+      XVI. _A. labyrinthibranchii_                                  514
+
+          Families: Labyrinthici (Climbing Perch, Gourami),
+          514--Luciocephalidæ, 519.
+
+     XVII. _A. lophotiformes_                                       519
+
+          Family: Lophotidæ, 519.
+
+    XVIII. _A. tæniiformes_                                         520
+
+          Family: Trachypteridæ (Ribbon-fishes), 520.
+
+      XIX. _A. notacanthiformes_                                    523
+
+          Family: Notacanthidæ, 523.
+
+
+    SECOND ORDER--ACANTHOPTERYGII PHARYNGOGNATHI                    523
+
+          Families: Pomacentridæ (Coral-fishes), 524--Labridæ
+          (Wrasses, Parrot-wrasses), 525--Embiotocidæ,
+          533--Chromides, 534.
+
+    THIRD ORDER--ANACANTHINI                                        537
+
+        I. _A. gadoidei_                                            537
+
+          Families: Lycodidæ, 537--Gadidæ (Cod-fishes, Hake,
+          Burbot, Ling, Rockling, Torsk), 539--Ophidiidæ
+          (Brotula, Fierasfer, Sand-eel, Congrogadus),
+          546--Macruridæ, 551.
+
+       II. _A. pleuronectoidei_                                     553
+
+          Family: Pleuronectidæ (Flat-fishes), 553.
+
+
+    FOURTH ORDER--PHYSOSTOMI                                        559
+
+          Families: _Siluridæ_; their skeleton, 559--divided into
+          eight subdivisions and sixteen groups; Clariina,
+          563--Plotosina, 563--Silurina, 565--Hypophthalmina,
+          566--Bagrina, 567--Amiurina, 567--Pimelodina,
+          568--Ariina, 569--Doradina, 572--Rhinoglanina,
+          573--Malapterurina (Electric Catfish), 574--Hypostomatina
+          (Preñadillas, Loricaria, etc.), 575--Aspredinina,
+          580--Nematogenyina and Trichomycterina, 581--Stegopholina,
+          581.
+
+          Families of Physostomi continued: Scopelidæ,
+          582--_Cyprinidæ_ (Carps), 587--divided into fourteen
+          groups, viz. Catostomina (Suckers), 588--Cyprinina (Carp,
+          Crucian Carp, Gold-fish, Barbels, Gudgeons),
+          589--Rohteichthyina, 596--Leptobarbina, 597--Rasborina,
+          597--Semiplotina, 598--Xenocypridina, 598--Leuciscina
+          (White fish, Tench, Dace, etc.), 598--Rhodeina,
+          601--Danionina, 601--Hypophthalmichthyina,
+          602--Abramidina (Bream, Bleak), 602--Homalopterina,
+          604--Cobitidina (Loaches), 604.
+
+          Families of Physostomi continued: Kneriidæ,
+          606--Characinidæ, 606--Cyprinodontidæ, 613--Heteropygii
+          (Blind Fish of the Mammoth Cave), 618--Umbridæ,
+          619--Scombresocidæ (Gar-pike, Saury, Half-beak, Flying
+          Fish), 619--Esocidæ (Pike), 623--Galaxiidæ, 624--Mormyridæ,
+          625--Sternoptychidæ, 627--Stomiatidæ, 629.
+
+          Families of Physostomi continued--_Salmonidæ_: Salmo,
+          difficulty of distinguishing species, 630; constant
+          specific characters, 635--hybrids, 638--sexual development,
+          638--migratory species and their retention in freshwater,
+          639--Growth of Salmonoids, 641--their domestication and
+          acclimatisation, 641--species enumerated, 642--Smelt and
+          Capelin, 646--Coregonus, 647--Grayling, 649--marine
+          genera, 650.
+
+          Families of Physostomi continued: Percopsidæ,
+          651--Haplochitonidæ, 651--Gonorhynchidæ, 652--Hyodontidæ
+          (Moon-eye), 653--Pantodontidæ, 653--Osteoglossidæ,
+          653--Clupeidæ (Herrings, Anchovies, Shads, Mossbanker,
+          Menhaden, etc.), 655--Bathythrissidæ, 663--Chirocentridæ,
+          663--Alepocephalidæ, 664--Notopteridæ, 664--Halosauridæ,
+          665--Hoplopleuridæ, 665--Gymnotidæ (Electric Eel),
+          666--Symbranchidæ, 668--Murænidæ (Eels, Congers, Murænas,
+          etc.), 669.
+
+
+    FIFTH ORDER--LOPHOBRANCHII                                      678
+
+        Families: Solenostomidæ, 678--Syngnathidæ (Pipe-fishes,
+        Sea-horses), 679.
+
+
+    SIXTH ORDER--PLECTOGNATHI                                       683
+
+        Families: Sclerodermi (File-fishes, Coffer-fishes),
+        684--Gymnodontes (Globe-fishes, Sun-fish), 686.
+
+
+                    THIRD SUB-CLASS--CYCLOSTOMATA.
+
+        Families: Petromyzontidæ (Lampreys), 691--Myxinidæ, 694.
+
+
+                    FOURTH SUB-CLASS--LEPTOCARDII.
+
+        Family: Cirrhostomi (Lancelets), 696.
+
+
+                               APPENDIX.
+
+    DIRECTIONS FOR COLLECTING AND PRESERVING FISHES                 697
+
+    ALPHABETICAL INDEX                                              707
+
+
+
+
+                         INTRODUCTORY REMARKS.
+
+
+According to the views generally adopted at present, all those
+Vertebrate animals are referred to the Class of Fishes, which living in
+water, breathe air dissolved in water by means of gills or branchiæ;
+whose heart consists of a single ventricle and single atrium; whose
+limbs, if present, are modified into fins, supplemented by unpaired,
+median fins; and whose skin is either naked, or covered with scales or
+osseous plates or bucklers. With few exceptions fishes are oviparous.
+However, there are not a few members of this Class which show a
+modification of one or more of these characteristics, as we shall see
+hereafter, and which, nevertheless, cannot be separated from it. The
+distinction between the Class of Fishes and that of Batrachians is very
+slight indeed.
+
+The branch of Zoology which treats of the internal and external
+structure of fishes, their mode of life, and their distribution in
+space and time, is termed Ichthyology.[1]
+
+
+
+
+                              CHAPTER I.
+
+                        HISTORY AND LITERATURE.
+
+
+[Sidenote: Aristotle.]
+
+The commencement of the history of Ichthyology coincides with that of
+Zoology generally. ARISTOTLE (384–322 B.C.) had a perfect knowledge
+of the general structure of fishes, which he clearly discriminates
+from the Aquatic animals with lungs and mammæ, _i.e._ Cetaceans, and
+from the various groups of Aquatic Invertebrates. He says that “the
+special characteristics of the true fishes consist in the branchiæ and
+fins, the majority having four fins, but those of an elongate form,
+as the eels, having two only. Some, as the _Muræna_, lack the fins
+altogether. The Rays swim with their whole body, which is spread out.
+The branchiæ are sometimes furnished with an opercle, sometimes without
+one, as is the case in the cartilaginous fishes.... No fish has hairs
+or feathers; most are covered with scales, but some have a rough or
+smooth skin. The tongue is hard, often toothed; and sometimes so much
+adherent that it seems to be wanting. The eyes have no lids; nor are
+any ears or nostrils visible, for what takes the place of nostrils is a
+blind cavity. Nevertheless they have the senses of tasting, smelling,
+and hearing. All have blood. All scaly fishes are oviparous, but the
+cartilaginous fishes (with the exception of the Sea-devil, which
+Aristotle places along with them) are viviparous. All have a heart,
+liver, and gall-bladder; but kidneys and urinary bladder are absent.
+They vary much in the structure of their intestines: for whilst the
+mullet has a fleshy stomach like a bird, others have no stomachic
+dilatation. Pyloric coeca are close to the stomach, variable in number;
+there are even some, like the majority of the cartilaginous fishes,
+which have none whatever. Two bodies are situated along the spine,
+which have the function of testicles, and open towards the vent, and
+which are much enlarged in the spawning season. The scales become
+harder with age. Not being provided with lungs, they have no voice, but
+several can emit grunting sounds. They sleep like other animals. In
+the majority the females exceed the males in size; and in the Rays and
+Sharks the male is distinguished by an appendage on each side of the
+vent.”
+
+Aristotle’s information on the habits of fishes, their migrations, mode
+and time of propagation, utility, is, as far as it has been tested,
+surprisingly correct. Unfortunately, only too often we lack the means
+of recognising the species of which he gives a description. His ideas
+of specific distinction were as vague as those of the fishermen whose
+nomenclature he adopted; it never occurred to him that such popular
+names are subject to change, or may be entirely lost with time, and
+the difficulty of deciphering his species is further increased by the
+circumstance that popular names are often applied by him to the same
+fish, or that different stages of growth are designated by distinct
+names. The number of fishes known to Aristotle seems to have been about
+115, all of which are inhabitants of the Ægean Sea.
+
+That one man should have discovered so many truths, and formed so
+sure a base for Zoology, is less surprising than the fact that for
+about eighteen centuries a science which seemed to offer particular
+attractions to men gifted with power of observation, was no farther
+advanced. Yet this is the case. Aristotle’s disciples, as well as his
+successors, remained satisfied to be his copiers or commentators,
+and to collect fabulous stories or vague notions. With very few
+exceptions (such as _Ausonius_, who wrote a small poem, in which
+he describes from his own observations the fishes of the Mosel)
+authors entirely abandoned original research. And it was not until
+about the middle of the sixteenth century that Ichthyology made a new
+step in advance by the appearance of _Belon_, _Rondelet_, and
+_Salviani_, who almost simultaneously published their grand works,
+by which the idea of species was established definitely and for all
+times.
+
+       *       *       *       *       *
+
+[Sidenote: Belon.]
+
+P. BELON travelled in the countries bordering on the eastern
+part of the Mediterranean, in the years 1547–50; he collected rich
+stores of positive knowledge, which he deposited in several works. The
+one most important for the progress of Ichthyology is that entitled “De
+aquatilibus libri duo” (Paris 1553; small 4to.) Belon knows about 110
+fishes, of which he gives rude, but generally recognisable, figures. In
+his descriptions he pays regard to the classical as well as vernacular
+nomenclature, and states the outward characteristics, sometimes even
+the number of fin-rays, frequently also the most conspicuous anatomical
+peculiarities.
+
+Although Belon but rarely gives definitions of the terms used by him,
+it is generally not very difficult to ascertain the limits which
+he intended to assign to each division of aquatic animals. He very
+properly divides them into such as are provided with blood, and into
+those without it: two divisions, called in modern language Vertebrate
+and Invertebrate aquatic animals. The former are classified by him
+according to sizes, the further subdivisions being based on the
+structure of the skeleton, mode of propagation, number of limbs, form
+of the body, and on the physical character of the localities inhabited
+by fishes. This classification is as follows:--
+
+     I. The larger fishes or Cetaceans.
+
+      _A._ Viviparous Cetaceans with bony skeletons (= Cetacea).
+
+      _B._ Viviparous Amphibians.
+
+        1. “With four limbs: Seals, Hippopotamus, Beaver, Otter, and
+             other aquatic Mammalia.
+
+        2. With two limbs: Mermaids, etc.
+
+      _C._ Oviparous Amphibians (= Reptiles and Frogs).
+
+      _D._ Viviparous Cartilaginous fishes.
+
+        1. Of an oblong form (= Sharks).
+
+        2. Of a flat form (= Rays and Lophius).
+
+      _E._ Oviparous Cartilaginous fishes (= Sturgeons and Silurus).
+
+      _F._ Oviparous Cetaceans, with spines instead of bones (=
+            large marine fishes, like the Thunny, Sword-fish,
+            Sciænoids, Bass, Gadoids, Trachypterus).
+
+    II. Spinous Oviparous fishes of a flat form (= Pleuronectidæ).
+
+   III. Fishes of a high form, like Zeus.
+
+    IV. Fishes of a snake like form (= Eels, Belone, Sphyræna).
+
+     V. Small Oviparous, spinous, scaly, marine fishes.
+
+      1. Pelagic kinds.
+
+      2. Littoral kinds.
+
+      3. Kinds inhabiting rocky localities.
+
+
+    VI. Fluviatile and Lacustrine fishes.
+
+       *       *       *       *       *
+
+[Sidenote: Salviani.]
+
+The work of the Roman ichthyologist, H. SALVIANI (1514–72),
+is characteristic of the high social position which the author held
+as the physician of three popes. Its title is “Aquatilium animalium
+historia” (Rom. 1554–57, fol.) It treats exclusively of the fishes of
+Italy. Ninety-two species are figured on seventy-six plates which, as
+regards artistic execution, are masterpieces of that period, although
+those specific characteristics which nowadays constitute the value
+of a zoological drawing, were entirely overlooked by the author or
+artist. No attempt is made at a natural classification, but the allied
+forms generally are placed in close proximity. The descriptions are
+quite equal to those given by Belon, entering much into the details of
+the economy and usefulness of the several species, and were evidently
+composed with the view of collecting in a readable form all that might
+prove of interest to the class of society in which the author moved.
+Salviani’s work is of a high standard, most remarkable for the age in
+which he lived. It could not fail to convey valuable instruction, and
+to render Ichthyology popular in the country to the fauna of which it
+was devoted, but it would not have advanced Ichthyology as science
+generally; and in this respect Salviani is not to be compared with
+Rondelet or Belon.
+
+       *       *       *       *       *
+
+[Sidenote: Rondelet.]
+
+G. RONDELET (1507–1557) had the great advantage over Belon in
+having received a medical education at Paris, and more especially in
+having gone through a complete course of instruction in anatomy as a
+pupil of Guentherus of Andernach. This is conspicuous throughout his
+works--“Libri de Piscibus marinis” (Lugd. 1554, fol.); and “Universæ
+aquatilium historiæ pars altera” (Lugd. 1555, fol.) Nevertheless
+they cannot be regarded as more than considerably enlarged editions
+of Belon’s work. For although he worked independently of the latter,
+and differs from him in numerous details, the system adopted by
+him is characterised by the same absence of the true principles of
+classification. Rondelet had a much more extensive knowledge of
+details. His work is almost entirely limited to European, and chiefly
+Mediterranean, forms, and comprises not less than 197 marine and 47
+freshwater fishes. His descriptions are more complete and his figures
+much more accurate than those of Belon; and the specific account is
+preceded by introductory chapters in which he treats in a general
+manner on the distinctions, the external and internal parts, and on
+the economy of fishes. Like Belon, he had no conception of the various
+categories of classification--for instance, confounding throughout his
+work the terms “genus” and “species;” but he had intuitively a notion
+of what his successors called a “species,” and his principal object was
+to collect and give as much information as possible of such species.
+
+For nearly a century the works of Belon and Rondelet remained the
+standard works of Ichthyology; but this science did not remain
+stationary during this period. The attention of naturalists was now
+directed to the products of foreign countries, especially the Spanish
+and Dutch possessions in the New World; and in Europe the establishment
+of anatomical schools and academies led to the careful investigation
+of the internal anatomy of the most remarkable European forms. Limited
+as these efforts were as to their scope, being directed either only to
+the fauna of some district, or to the dissection of a single species,
+they were sufficiently numerous to enlarge the views of naturalists,
+and to destroy that fatal dependency on preceding authorities which had
+continued to keep in bonds the minds of even such men as Rondelet and
+Belon.
+
+[Sidenote: W. Piso. G. Margrav.]
+
+The most noteworthy of those who were active in tropical countries
+are W. PISO and G. MARGRAV. They accompanied as physicians the Dutch
+Governor, Prince Moritz of Nassau, to Brazil (1637–44). Margrav
+especially studied the fauna of the country, and although he died
+before his return to Europe, his observations were published by his
+colleague, and embodied in a work “Historia naturalis Braziliæ”
+(Lugd. 1648, fol.), in which the fourth book treats of the fishes. He
+describes about 100 species, all of which had been previously unknown,
+in a manner far superior to that of his predecessors. The accompanying
+figures are not good, but nearly always recognisable, and giving a
+fair idea of the form of the fish. Margrav himself, with the aid of an
+artist, had made a most valuable collection of coloured drawings of the
+objects observed and described by him, but many years were allowed to
+pass before it was scientifically utilised by Bloch and others.
+
+[Sidenote: Anatomists, 1600–1700.]
+
+Of the men who left records of their anatomical researches, we may
+mention BORELLI (1608–79), who wrote a work “De motu animalium” (Rom.
+1680, 4to), in which he explained the mechanism of swimming, and the
+function of the air-bladder; M. MALPIGHI (1628–94), who examined the
+optic nerve of the sword-fish; the celebrated J. SWAMMERDAM (1637–80),
+who described the intestines of numerous fishes; and J. DUVERNEY
+(1648–1730), who entered into detailed researches of the organs of
+respiration.
+
+       *       *       *       *       *
+
+A new era in the history of Ichthyology commences with _Ray_,
+_Willughby_, and _Artedi_, who were the first to recognise
+the true principles by which the natural affinities of animals should
+be determined. Their labours stand in so intimate a connection with
+each other that they represent only one stride in the progress of this
+science.
+
+       *       *       *       *       *
+
+[Sidenote: Ray and Willughby]
+
+J. RAY (born 1628 in Essex, died 1705), was the friend and
+guide of F. WILLUGHBY (1635–72). They had recognised that a
+thorough reform of the treatment of the vegetable and animal kingdoms
+had become necessary; that the only way of bringing order into the
+existing chaos was that of arranging the various forms with regard to
+their structure; that they must cease to be burdened with inapplicable
+passages and quotations of the ancient writers, and to perpetuate
+the erroneous or vague notions of their predecessors. They abandoned
+speculation, and adhered to facts only. One of the first results, and
+perhaps the most important, of their method was, that having recognised
+the “species” as such, they defined this term, and fixed it as the
+base, from which all sound zoological knowledge has to start.
+
+Although they had divided their work thus that Ray attended to the
+plants principally, and Willughby to the animals, the “Historia
+piscium” (Oxford, 1686, fol.), which bears Willughby’s name on the
+titlepage, and was edited by Ray, is clearly their joint production. A
+great part of the observations contained in it were collected during
+their common journeys in Great Britain and on the Continent, and it is
+no exaggeration to say that at that time these two Englishmen knew the
+fishes of the Continent, especially those of Germany, better than any
+other Continental zoologist.
+
+By the definition of fishes as animals with blood, breathing by gills,
+provided with a single ventricle of the heart, covered with scales or
+naked; the Cetaceans are excluded. Yet, at a later period Ray appears
+to have been afraid of so great an innovation as the separation of
+whales from fishes, and, therefore, he invented a definition of fish
+which comprises both. The fishes proper are then arranged in the
+first place according to the cartilaginous or osseous nature of the
+skeleton; further subdivisions being formed with regard to the general
+form of the body, the presence or absence of ventral fins, the soft or
+spinous structure of the dorsal rays, the number of dorsal fins, etc.
+Not less than 420 species are thus arranged and described, of which
+about 180 were known to the authors from autopsy: a comparatively
+small proportion, descriptions and figures still forming at that time
+in a great measure a substitute for collections and museums. With the
+increasing accumulation of forms the want of a fixed nomenclature is
+now more and more felt.
+
+       *       *       *       *       *
+
+[Sidenote: P. Artedi.]
+
+PETER ARTEDI would have been a great ichthyologist if Ray or
+Willughby had never preceded him. But he was fully conscious of the
+fact that both had prepared the way for him, and therefore he derived
+all possible advantages from their works. Born in 1705 in Sweden, he
+studied with Linnæus at Upsala; from an early period he devoted himself
+entirely to the study of fishes, and was engaged in the arrangement and
+description of the ichthyological collection of _Seba_, a wealthy
+Dutchman who had formed the then perhaps richest museum, when he was
+accidentally drowned in one of the canals of Amsterdam in the year
+1734, at an age of twenty-nine years. His manuscripts were fortunately
+rescued by an Englishman, Cliffort, and edited by his early friend
+Linnæus.
+
+The work is divided into the following parts:--
+
+1. In the “Bibliotheca Ichthyologica” Artedi gives a very complete list
+of all preceding authors who have written on fishes, with a critical
+analysis of their works.
+
+2. The “Philosophia Ichthyologica” is devoted to a description of
+the external and internal parts of fishes; Artedi fixes a precise
+terminology of all the various modifications of the organs,
+distinguishes between those characters which determine a genus and such
+as indicate a species or merely a variety; in fact he establishes the
+method and principles which subsequently have guided every systematic
+ichthyologist.
+
+3. The “Genera Piscium” contains well-defined diagnoses of forty-five
+genera, for which he fixes an unchangeable nomenclature.
+
+4. In the “Species Piscium” descriptions of seventy-two species,
+examined by himself, are given; descriptions which even now are models
+of exactitude and method.
+
+5. Finally, in the “Synonymia Piscium” references to all previous
+authors are arranged for every species, very much in the same manner
+which is adopted in the systematic works of the present day.
+
+[Sidenote: Linnæus.]
+
+Artedi has been justly called the Father of Ichthyology. So perfect was
+his treatment of the subject, that even LINNÆUS could no more
+improve it, only modify and add to it; and as far as Ichthyology is
+concerned, Linnæus has scarcely done anything beyond applying binominal
+terms to the species properly described and classified by Artedi.
+
+Artedi had divided the fishes proper into four orders, viz.
+_Malacopterygii_, _Acanthopterygii_, _Branchiostegi_, and
+_Chondropterygii_, of which the third only, according to our present
+knowledge, appears to be singularly heterogeneous, as it comprises
+_Balistes_, _Ostracion_, _Cyclopterus_, and _Lophius_. Linnæus, besides
+separating the Cetaceans entirely from the class of fishes (at least
+since the 10th edition of the “Systema Naturæ”) abandoned Artedi’s
+order of Branchiostegi, but substituted a scarcely more natural
+combination by joining it with Artedi’s Chondropterygians, under the
+name of “Amphibia nantes.”
+
+His classification of the genera appears in the 12th edition of the
+“Systema,” thus--
+
+
+       AMPHIBIA NANTES.
+
+
+   _Spiraculis compositis._
+
+       Petromyzon.
+       Raia.
+       Squalus.
+       Chimæra.
+
+
+   _Spiraculis solitariis._
+
+       Lophius.
+       Acipenser.
+       Cyclopterus.
+       Balistes.
+       Ostracion.
+       Tetrodon.
+       Diodon.
+       Centriscus.
+       Syngnathus.
+       Pegasus.
+
+
+   PISCES APODES.
+
+       Muræna.
+       Gymnotus.
+       Trichiurus.
+       Anarhichas.
+       Ammodytes.
+       Ophidium.
+       Stromateus.
+       Xiphias.
+
+
+   PISCES JUGULARES.
+
+       Callionymus.
+       Uranoscopus.
+       Trachinus.
+       Gadus.
+       Blennius.
+
+
+   PISCES THORACICI.
+
+       Cepola.
+       Echeneis.
+       Coryphæna.
+       Gobius.
+       Cottus.
+       Scorpæna.
+       Zeus.
+       Pleuronectes.
+       Chæetodon.
+       Sparus.
+       Labrus.
+       Sciæna.
+       Perca.
+       Gasterosteus.
+       Scomber.
+       Mullus.
+       Trigla.
+
+
+   PISCES ABDOMINALES.
+
+       Cobitis.
+       Amia.
+       Silurus.
+       Teuthis.
+       Loricaria.
+       Salmo.
+       Fistularia.
+       Esox.
+       Elops.
+       Argentina.
+       Atherina.
+       Mugil.
+       Mormyrus.
+       Exocœtus.
+       Polynemus.
+       Clupea.
+       Cyprinus.
+
+[Sidenote: Gronow and Klein.]
+
+Two contemporaries of _Linnæus_ attempted a systematic arrangement
+of fishes; both had considerable opportunities for their study,
+especially in possessing extensive collections; but neither exercised
+any influence on the progress of Ichthyology. The one, L. T. GRONOW,
+a German who resided in Holland, closely followed the arrangements
+proposed by Artedi and Linnæus, and increased the number of genera and
+species from the contents of his own museum. He published two works,
+“Museum Ichthyologicum” (Lugd. 1754–6, fol.), and “Zoophylacium” (Lugd.
+1763–81, fol.); a posthumous work, containing numerous excellent
+descriptions of new forms was published by J. E. Gray in 1854 under the
+title of “Systema Ichthyologicum.” To Gronow also is due the invention
+of preparing flat skins of fishes in a dry state, and preserving them
+in the manner of a herbarium. The specimens thus prepared by him belong
+to the oldest which have been preserved down to our time.
+
+Much less important are the ichthyological labours of J. T. KLEIN
+(1685–1759). They are embodied in five parts (_Missus_) of a work
+entitled “Historia naturalis piscium” (Sedæ, 1740–9, 4to.) He regarded
+a system merely as the means of recognising the various forms of
+animals, not as the expression of their natural affinities; and that
+method seemed to him to be the most perfect by which an animal could
+be most readily determined. He eschewed all reference to minute or
+anatomical characters. Hence his system is a series of the most
+unnatural combinations, and we cannot be surprised that Linnæus passed
+in silence over Klein’s labours.
+
+       *       *       *       *       *
+
+[Sidenote: Pupils and Successors of Linnæus]
+
+The works of Artedi and Linnæus excited fresh activity, more especially
+in Scandinavia, Holland, Germany, and England, such as has not been
+equalled in the history of biological science either before or
+after. Whilst some of the pupils and followers of Linnæus devoted
+themselves to an examination and study of the fauna of their native
+countries, others proceeded on voyages of discovery to foreign and
+distant countries. Of these latter the following may be specially
+mentioned:--_O. Fabricius_ worked out the Fauna of Greenland, _Kalm_
+collected in North America, _Hasselquist_ in Egypt and Palestine,
+_Brünnich_ in the Mediterranean, _Osbeck_ in Java and China,
+_Thurnberg_ in Japan; _Forskål_ examined and described the fishes of
+the Red Sea; _Steller_, _Pallas_, _S. T. Gmelin_, and _Güldenstedt_
+traversed nearly the whole of the Russian Empire in Europe and
+Asia. Others attached themselves as naturalists to the celebrated
+circumnavigators of the last century, like the two _Forsters_ (father
+and son), and _Solander_, who accompanied Cook; _Commerson_, who
+travelled with Bougainville; and _Sonnerat_. Numerous new and startling
+forms were discovered by those men, and the foundation was laid of the
+knowledge of the geographical distribution of animals.
+
+Of those who studied the fishes of their native country the most
+celebrated are _Pennant_ (Great Britain), _O. F. Müller_ (Denmark),
+_Duhamel_ (France), _Meidinger_ (Austria), _Cornide_ (Spain), _Parra_
+(Cuba).
+
+The materials brought together by those and other zoologists were so
+numerous that, not long after the death of Linnæus, the necessity was
+felt of collecting them in a compendious form. Several compilators
+undertook this task; they embodied the recent discoveries in new
+editions of Artedi’s and Linné’s classical works, but not possessing
+either a knowledge of the subject or any critical discernment, they
+only succeeded in covering those noble monuments under a mass of
+confused rubbish. For Ichthyology it was fortunate that two men at
+least, Bloch and Lacépède, made it a subject of long and original
+research.
+
+       *       *       *       *       *
+
+[Sidenote: M. E. Bloch.]
+
+MARK ELIEZER BLOCH, born in the year 1723 at Anspach in Germany,
+practised as a physician in Berlin; he had reached an age of fifty-six
+years when he commenced to write on ichthyological subjects. To
+commence at his age a work in which he intended not only to give full
+descriptions of the species known to him from specimens or drawings,
+but also to illustrate every species in a style truly magnificent for
+his time, was an undertaking of the execution of which an ordinary man
+would have despaired. Yet he accomplished not only this task, but even
+more, as we shall see hereafter.
+
+His work consists of two divisions:--
+
+1. “Oeconomische Naturgeschichte der Fische Deutschlands” (Berl.
+1782–4, 4to. Plates in fol.)
+
+2. “Naturgeschichte der auslændischen Fische” (Berl. 1785–95, 4to.
+Plates in fol.)
+
+Bloch’s work is unique, and probably will for ever remain so. Although
+Cuvier fifty years later undertook a similar general work on fishes,
+the subject had then become too extensive to allow of an attempt of
+giving illustrations of all the species, or illustrations of a similar
+size and costliness.
+
+The first division of the work, which is devoted to a description of
+the fishes of Germany, is entirely original, and based upon Bloch’s
+own observations. His descriptions as well as figures were made from
+nature, and are, with but few exceptions, still serviceable; many
+continue to be the best existing in literature.
+
+Bloch was less fortunate and is much less reliable in his natural
+history of foreign fishes. For many of the species he had to rely
+on more or less incorrect drawings and descriptions of travellers;
+frequently, also, he was deceived as to the origin of specimens which
+he acquired by purchase. Hence his accounts contain numerous confusing
+errors which it would have been difficult to correct, if not nearly the
+whole of the materials on which his work is based had been preserved in
+the collections at Berlin.
+
+After the completion of his Ichthyology Bloch occupied himself with
+systematic work. He prepared a general system of fishes, in which he
+arranged not only those described in his great work, but also those
+with which he had become acquainted afterwards from the descriptions of
+others. The work was ably edited and published after Bloch’s death by a
+philologist, _J. G. Schneider_, under the title “M. E. Blochii Systema
+ichthyologiæ iconibus ex. illustratum” (Berl. 1801, 8vo.) The number of
+species enumerated in it amounts to 1519. The system is based upon the
+number of the fins, the various orders being termed _Hendecapterygii_,
+_Decapterygii_, etc. We need not add that an artificial method like
+this led to the most unnatural combinations or severances.
+
+[Sidenote: Lacépède.]
+
+Bloch’s Ichthyology remained for many years the standard work, and,
+by the great number of excellent illustrations, proved a most useful
+guide to the student. But as regards originality of thought, Bloch was
+far surpassed by his contemporary, B. G. E. DE LACÉPÈDE, born at Agen,
+in France, in 1756, a man of great and general erudition, who died as
+Professor of the Museum of Natural History of Paris in 1826.
+
+Lacépède had to contend with great difficulties in the preparation
+of his “Histoire des Poissons” (Paris, 1798–1803, 4to, in 5 vols.),
+which was written during the most disturbed period of the French
+Revolution. A great part of it was composed whilst the author was
+separated from collections and books, and had to rely on his notes and
+manuscripts only. Even the works of Bloch and other contemporaneous
+authors remained unknown, or at least inaccessible, to him for a long
+time. Therefore we cannot be surprised that his work abounds in all
+those errors to which a compiler is subject. The same species not only
+appears under two and more distinct specific names, but it sometimes
+happens that the author understands so little the source from which
+he derives his information that the description is referred to one
+genus and the accompanying figure to another. The names of genera are
+unduly multiplied; and the figures with which the work is illustrated
+are far inferior to those of Bloch. Thus the influence of Lacépède
+on the progress of Ichthyology was infinitely less than that of his
+fellow-labourer; and the labour caused to his successors by correcting
+the numerous errors into which he has fallen, probably outweighs the
+assistance which they derived from his work.
+
+[Sidenote: Anatomists.]
+
+The work of the principal cultivators of Ichthyology in the period
+between Ray and Lacépède was chiefly systematic and descriptive, but
+also the internal organisation of fishes received attention from more
+than one great anatomist. _Haller_, _Camper_, and _Hunter_, examined
+the nervous system and organs of sense; and more especially _Alexander
+Monro_ (the son) published a classical work, “The Structure and
+Physiology of Fishes explained and compared with those of Man and other
+Animals” (Edinb. 1785, fol.) The electric organs of fishes (_Torpedo_
+and _Gymnotus_) were examined by _Réaumur_, _Allamand_, _Bancroft_,
+_Walsh_, and still more exactly by _J. Hunter_. The mystery of the
+propagation of the Eel called forth a large number of essays, and even
+the artificial propagation of Salmonidæ was known and practised by
+_Gleditsch_ (1764).
+
+[Sidenote: Faunists.]
+
+Bloch and Lacépède’s works were almost immediately succeeded by the
+labours of _Cuvier_, but his early publications were of necessity
+tentative, preliminary, and fragmentary, so that a short period elapsed
+before the spirit infused by this great anatomist into Ichthyology
+could exercise its influence on all workers in this field. Several
+of such antecuvierian works must be mentioned on account of their
+importance to our knowledge of certain Faunas: the “Descriptions and
+Figures of Two Hundred Fishes collected at Vizagapatam on the coast
+of Coromandel” (Lond. 1803; 2 vols. in fol.), by _Patrick Russel_;
+and “An Account of the Fishes found in the River Ganges and its
+branches” (Edinb. 1822; 2 vols. in 4to), by _F. Hamilton_ (formerly
+_Buchanan_)--works distinguished by a greater accuracy of their
+drawings (especially in the latter), than was ever attained before.
+A “Natural History of British Fishes” was published by _E. Donovan_
+(Lond. 8vo, 1802–8); and the Mediterranean Fauna formed the study of
+the lifetime of _A. Risso_ (“Ichthyologie de Nice.” Paris, 1810, 8vo;
+and “Histoire naturelle de l’Europe Meridionale.” Paris, 1827, 8vo). A
+slight beginning in the description of the fishes of the United States
+was made by _S. L. Mitchell_, who published, besides various papers, a
+“Memoir on the Ichthyology of New York,” in 1815.[2]
+
+       *       *       *       *       *
+
+[Sidenote: G. Cuvier.]
+
+G. CUVIER did not occupy himself with the study of fishes merely
+because this class formed part of the “Règne animal,” but he devoted
+himself to it with particular predilection. The investigation of their
+anatomy, and especially of their skeleton, was taken up by him at an
+early period, and continued until he had succeeded in completing so
+perfect a framework of the system of the whole class that his immediate
+successors could content themselves with filling up those details for
+which their master had no leisure. Indefatigable in examining all the
+external and internal characters of the fishes of a rich collection, he
+ascertained the natural affinities of the infinite variety of fishes,
+and accurately defined the divisions, orders, families, and genera
+of the class, as they appear in the various editions of the “Règne
+animal.” His industry equalled his genius: he opened connections with
+almost every accessible part of the globe; not only French travellers
+and naturalists, but also Germans, Englishmen, Americans, rivalled one
+another to assist him with collections; and for many years the Muséum
+of the Jardin des Plantes was the centre where all ichthyological
+treasures were deposited. Thus Cuvier brought together a collection
+the like of which had never been seen before, and which, as it contains
+all the materials on which his labours were based, must still be
+considered to be the most important. Soon after the year 1820, Cuvier,
+assisted by one of his pupils, A. VALENCIENNES, commenced his great
+work on fishes, “Histoire naturelles des Poissons,” of which the first
+volume appeared in 1828. The earlier volumes, in which Cuvier himself
+took his share, bear evidence of the freshness and love with which both
+authors devoted themselves to their task. After Cuvier’s death in 1832
+the work was left entirely in the hands of Valenciennes, whose energy
+and interest gradually slackened, to rise to the old standard in some
+parts only, as, for instance, in the treatise on the Herring. He left
+the work unfinished with the twenty-second volume (1848), which treats
+of the Salmonoids. Yet, incomplete as it is, it is indispensable to the
+student.
+
+There exist several editions of the work, which, however, have the same
+text. One, printed in 8vo, with coloured or plain figures, is the one
+in common use among ichthyologists. A more luxurious edition in 4to has
+a different pagination, and therefore is most inconvenient to use.
+
+As mentioned above, the various parts of the work are very unequally
+worked out. Many of the species are described in so masterly a
+manner that a greater excellency of method can hardly be conceived.
+The history of the literature of these species is entered into with
+minuteness and critical discernment; but in the later volumes, numerous
+species are introduced into the system without any description, or
+with a few words only, comparing a species with one or more of its
+congeners. Cuvier himself, at a late period of his life, seems to have
+grown indifferent as to the exact definition of his species: a failing
+commonly observed among Zoologists when attention to descriptive
+details becomes to them a tedious task. What is more surprising is,
+that a man of his anatomical and physiological knowledge should have
+overlooked the fact that secondary sexual characters are developed in
+fishes as in any other class of animals, and that fishes undergo great
+changes during growth; and, consequently, that he described almost
+all such sexual forms and different stages of growth under distinct
+specific and even generic names.
+
+The system finally adopted by Cuvier is the following:--
+
+
+                         _A._ POISSONS OSSEUX.
+
+                I.--A BRANCHIES EN PEIGNES OU EN LAMES.
+
+                    1. A MÂCHOIRE SUPÉRIEURE LIBRE.
+
+                        a. _Acanthoptérygiens._
+
+    Percoïdes.
+    Polynèmes.
+    Mulles.
+    Joues cuirassées.
+    Scienoïdes.
+    Sparoïdes.
+    Chétodonoïdes.
+    Scomberoïdes.
+    Muges.
+    Branchies labyrinthiques.
+    Lophioïdes.
+    Gobioïdes.
+    Labroïdes.
+
+
+                        b. _Malacoptérygiens._
+
+    _Abdominaux._
+    Cyprinoïdes.
+    Siluroïdes.
+    Salmonoïdes.
+    Clupeoïdes.
+    Lucioïdes.
+
+    _Subbrachiens._
+    Sparoïdes.
+    Pleuronectes.
+    Discoboles.
+
+    _Apodes._
+    Murenoïdes.
+
+                    2. A MÂCHOIRE SUPÉRIEURE FIXÉE.
+
+    Sclérodermes.
+    Gymnodontes.
+
+                 II. A BRANCHIES EN FORME DE HOUPPES.
+
+    Lophobranches.
+
+               _B._ CARTILAGINEUX OU CHONDROPTÉRYGIENS.
+
+    Sturioniens.
+    Plagiostomes.
+    Cyclostomes.
+
+We have to compare this system with that of Linnæus if we wish
+to measure the gigantic stride Ichthyology has made during the
+intervening period of seventy years. The various characters employed
+for classification have been examined throughout the whole class,
+and their relative importance has been duly weighed and understood.
+Though Linnæus had formed a category of “Amphibia nantes” for fishes
+with a cartilaginous skeleton, which should coincide with Cuvier’s
+“Poissons Cartilagineux,” he had failed to understand the very nature
+of cartilage, apparently comprising by this term any skeletal framework
+of less firmity than ordinary bone. Hence he considered _Lophius_,
+_Cyclopterus_, _Syngnathus_ to be cartilaginous fishes. Adopting the
+position and development of the ventral fins as a highly important
+character, he was obliged to associate fishes with rudimentary and
+inconspicuous ventral fins, like _Trichiurus_, _Xiphias_, etc., with
+the true Eels. The important category of a “family” appears now in
+Cuvier’s system fully established as that intermediate between genus
+and order. Important changes in Cuvier’s system have been made and
+proposed by his successors, but in the main it is still that of the
+present day.
+
+Cuvier had extended his researches beyond the living forms, into
+the field of palæontology; he was the first to observe the close
+resemblance of the scales of the fossil _Palæoniscus_ to those of the
+living _Polypterus_ and _Lepidosteus_, the prolongation and identity of
+structure of the upper caudal lobe in _Palæoniscus_ and the Sturgeons,
+the presence of peculiar “fulcra” on the anterior margin of the dorsal
+fin in _Palæoniscus_ and _Lepidosteus_: inferring from these facts
+that that fossil genus was allied _either_ to the Sturgeons _or_ to
+_Lepidosteus_. But it did not occur to him that there was a close
+relationship between those recent fishes. _Lepidosteus_ and, with
+it, the fossil genus remained in his system a member of the order of
+_Malacopterygii abdominales_.
+
+It was left to L. AGASSIZ (born 1807, died 1873) to point out the
+importance of the character of the structure of the scales, and to open
+a path towards the knowledge of a whole new sub-class of fishes, the
+_Ganoidei_.
+
+Impressed with the fact that the peculiar scales of _Polypterus_ and
+_Lepidosteus_ are common to all fossil osseous fishes down to the
+chalk, he takes the structure of the scales generally as the base for
+an ichthyological system, and distinguishes four orders:--
+
+1. _Placoids._--Without scales proper, but with scales of enamel,
+sometimes large, sometimes small and reduced to mere points (Rays,
+Sharks, and Cyclostomi, with the fossil _Hybodontes_).
+
+2. _Ganoids._--With angular bony scales, covered with a thick
+stratum of enamel: to this order belong the fossil Lepidoides,
+Sauroides, Pycnodontes, and Coelacanthi; the recent Polypterus,
+Lepidosteus, Sclerodermi, Gymnodontes, Lophobranches, and Siluroides;
+also the Sturgeons.
+
+3. _Ctenoids._--With rough scales, which have their free margins
+denticulated: Chætodontidæ, Pleuronectidæ, Percidæ, Polyacanthi,
+Sciænidæ, Sparidæ, Scorpænidæ, Aulostomi.
+
+4. _Cycloids._--With smooth scales, the hind margin of which lacks
+denticulation: Labridæ, Mugilidæ, Scombridæ, Gadoidei, Gobiidæ,
+Murænidæ, Lucioidei, Salmonidæ, Clupeidæ, Cyprinidæ.
+
+We have no hesitation in affirming that if Agassiz had had an
+opportunity of acquiring a more extensive and intimate knowledge of
+existing fishes before his energies were absorbed in the study of
+their fossil remains, he himself would have recognised the artificial
+character of his classification. The distinctions between cycloid and
+ctenoid scales, between placoid and ganoid fishes are vague, and can
+hardly be maintained. As far as the living and post-cretacean forms
+are concerned, the vantage-ground gained by Cuvier was abandoned
+by him; and therefore his system could never supersede that of his
+predecessors, and finally shared the fate of every classification based
+on the modifications of one organ only. But Agassiz has the merit of
+having opened an immense new field of research by his study of the
+infinite variety of fossil forms. In his principal work, “Recherches
+sur les Poissons fossiles,” (Neuchatel, 1833–43, 4to, atlas in fol.),
+he placed them before the world arranged in a methodical manner, with
+excellent descriptions and illustrations. His power of discernment and
+penetration in determining even the most fragmentary remains is truly
+astonishing; and if his order of Ganoids is an assemblage of forms very
+different from that as it is circumscribed now, he was at any rate the
+first who recognised that such an order of fishes exists.
+
+       *       *       *       *       *
+
+[Sidenote: J. Müller.]
+
+The discoverer of the _Ganoidei_ was succeeded by their explorer,
+JOHANNES MÜLLER (born 1801, died 1858). In his classical memoir “Ueber
+den Bau und die Grenzen der Ganoiden” (Berlin, 1846; 4to), he showed
+that the Ganoids differed from all the other osseous fishes, and agreed
+with the Plagiostomes, in the structure of their heart. By this primary
+character, all heterogeneous elements, as _Siluroids_, _Osteoglossidæ_,
+etc., were eliminated from the order as understood by Agassiz. On the
+other hand, he did not recognise the affinity of _Lepidosiren_ to the
+Ganoids, but established for it a distinct sub-class, _Dipnoi_, which
+he placed at the opposite end of the system. By his researches into the
+anatomy of the Lampreys and Amphioxus, their typical distinctness from
+other cartilaginous fishes was proved; they became the types of two
+other sub-classes, _Cyclostomi_ and _Leptocardii_.
+
+Müller proposed several other not unimportant modifications of the
+Cuvierian system; and although all cannot be maintained as the most
+natural arrangements, yet his researches have given us a much more
+complete knowledge of the organisation of the Teleosteous fishes,
+and later enquiries have shown that, on the whole, the combinations
+proposed by him require only some further modification and another
+definition to render them perfectly natural.
+
+Under the name of _Pharyngognathi_ he combined fishes with the lower
+pharyngeals coalesced into one bone, viz. the Labroids, Chromides, and
+Scombresoces. The association of the third family with the two former
+seemed to himself a somewhat arbitrary proceeding; and it had to be
+abandoned again, when a number of fishes which cannot be separated
+from the Acanthopterygians, were found to possess the same united
+pharyngeals.
+
+A more natural combination is the union of the Cod-fishes with the
+Flat-fishes into the order _Anacanthini_. Flat-fishes are in fact
+nothing but asymmetrical Cod-fishes. Müller separates them from the
+remaining Malacopterygians by the absence of a connecting duct between
+the air-bladder and oesophagus. However, it must be admitted that the
+examination of those fishes, and especially of the young stages, is not
+complete enough to raise the question beyond every doubt, whether the
+presence or absence of that duct is an absolutely distinctive character
+between Anacanths and Malacopterygians.
+
+Many of the families established by Cuvier were reexamined and better
+defined by Müller, as may be seen from the following outline of his
+system:--
+
+
+                        Sub-classis I.--Dipnoi.
+
+                         Ordo I.--Sirenoidei.
+
+    Fam. 1. Sirenoidei.
+
+
+                      Sub-classis II.--Teleostei.
+
+                        Ordo I.--Acanthopteri.
+
+    Fam. 1. Percoidei.
+     „   2. Cataphracti.
+     „   3. Sparoidei.
+     „   4. Sciænoidei.
+     „   5. Labyrinthiformes.
+     „   6. Mugiloidei.
+     „   7. Notacanthini.
+     „   8. Scomberoidei.
+     „   9. Squamipennes.
+     „  10. Taenioidei.
+     „  11. Gobioidei.
+     „  12. Blennioidei.
+     „  13. Pediculati.
+     „  14. Theutyes.
+     „  15. Fistulares.
+
+
+                        Ordo II.--Anacanthini.
+
+                 Sub-ordo I.--Anacanthini sub-brachii.
+
+    Fam. 1. Gadoidei.
+     „   2. Pleuronectides.
+
+
+                   Sub-ordo II.--Anacanthini apodes.
+
+    Fam. 1. Ophidini.
+
+
+                      Ordo III.--Pharyngognathi.
+
+             Sub-ordo I.--Pharyngognathi acanthopterygii.
+
+    Fam. 1. Labroidei cycloidei.
+     „   2. Labroidei ctenoidei.
+     „   3. Chromides.
+
+
+             Sub-ordo II.--Pharyngognathi malacopterygii.
+
+    Fam. 1. Scomberesoces.
+
+
+                         Ordo IV.--Physostomi.
+
+                 Sub-ordo I.--Physostomi abdominales.
+
+    Fam. 1. Siluroidei.
+     „  2. Cyprinoidei.
+     „   3. Characini.
+     „   4. Cyprinodontes.
+     „   5. Mormyri.
+     „   6. Esoces.
+     „   7. Galaxiæ.
+     „   8. Salmones.
+     „   9. Scopelini.
+     „  10. Clupeidæ.
+     „  11. Heteropygii.
+
+
+            Sub-ordo II.--Physostomi apodes s. anguillares.
+
+    Fam. 12. Murænoidei.
+     „   13. Gymnotini.
+     „   14. Symbranchii.
+
+
+                        Ordo V.--Plectognathi.
+
+    Fam. 1. Balistini.
+     „   2. Ostraciones.
+     „   3. Gymnodontes.
+
+
+                       Ordo VI.--Lophobranchii.
+
+    Fam. 1. Lophobranchi.
+
+
+                      Sub-classis III.--Ganoidei.
+
+                          Ordo I.--Holostei.
+
+    Fam. 1. Lepidosteini.
+     „   2. Polypterini.
+
+
+                        Ordo II.--Chondrostei.
+
+    Fam. 1. Acipenserini,
+     „   2. Spatulariæ.
+
+
+              Sub-classis IV.--Elasmobranchi s. Selachii.
+
+                         Ordo I.--Plagiostomi.
+
+                        Sub-ordo I.--Squalidæ.
+
+    Fam. 1. Scyllia.
+     „   2. Nyctitantes.
+     „   3. Lamnoidei.
+     „   4. Alopeciæ.
+     „   5. Cestraciones.
+     „   6. Rhinodontes.
+     „   7. Notidani.
+     „   8. Spinaces.
+     „   9. Scymnoidei.
+     „  10. Squatinæ.
+
+
+                         Sub-ordo II.--Rajidæ.
+
+    Fam. 11. Squatinorajæ.
+     „   12. Torpedines.
+     „   13. Rajæ.
+     „   14. Trygones.
+     „   15. Myliobatides.
+     „   16. Cephalopteræ.
+
+
+                        Ordo II.--Holocephali.
+
+    Fam. 1. Chimaeræ.
+
+
+            Sub-classis V.--Marsipobranchii s. Cyclostomi.
+
+                         Ordo I.--Hyperoartii.
+
+    Fam. 1. Petromyzonini.
+
+
+                        Ordo II.--Hyperotreti.
+
+    Fam. 1. Myxinoidei.
+
+
+                     Sub-classis VI.--Leptocardii.
+
+                         Ordo I.--Amphioxini.
+
+    Fam. 1. Amphioxini.
+
+[Sidenote: Discovery of Ceratodus.]
+
+The discovery (in the year 1871) of a living representative of a
+genus hitherto believed to be long extinct, _Ceratodus_, threw
+a new light on the affinities of Fishes. The author who had the good
+fortune of examining this fish, was enabled to show that, on the one
+hand, it was a form most closely allied to _Lepidosiren_; on the
+other, that it could not be separated from the Ganoid fishes, and
+therefore that also _Lepidosiren_ was a Ganoid: a relation pointed
+at already by Huxley in a previous paper on “Devonian Fishes.” This
+discovery led to further considerations[3] of the relative characters
+of Müller’s sub-classes, and to the system which is followed in the
+present work.
+
+Having followed the development of the ichthyological system down to
+the latest time, we have to retrace our steps to enumerate the most
+important contributions to Ichthyology which appeared contemporaneously
+with or subsequently to the publication of Cuvier and Valenciennes’s
+great work. As in other branches of Zoology, activity increased almost
+with every year; and for convenience’s sake we may arrange these works
+in three rubrics.
+
+
+[Sidenote: Recent Works.]
+
+        I.--VOYAGES, CONTAINING GENERAL ACCOUNTS OF ZOOLOGICAL
+                             COLLECTIONS.
+
+
+                             A. _French._
+
+1. “Voyage autour du monde sur les Corvettes de S. M. l’Uranie et la
+Physicienne, sous le commandement de M. Freycinet. Zoologie: Poissons
+par _Quoy_ et _Gaimard_.” (Paris, 1824, 4to, atlas fol.)
+
+2. “Voyage de la Coquille. Zoologie par _Lesson_.” (Paris,
+1826–30, 4to, atlas fol.)
+
+3. “Voyage de l’Astrolabe, sous le commandement de M. J. Dumont
+d’Urville. Poissons par _Quoy_ et _Gaimard_.” (Paris, 1834,
+8vo, atlas fol.)
+
+4. “Voyage au Pôle Sud par M. J. Dumont d’Urville. Poissons par
+_Hombron_ et _Jacquinot_.” (Paris, 1853–4, 8vo, atlas fol.)
+
+
+                             B. _English._
+
+1. “Voyage of H.M.S. Sulphur. Fishes by _J. Richardson_.” (Lond.
+1844–5, 4to.)
+
+2. “Voyage of H.M.S.S. Erebus and Terror. Fishes by _J. Richardson_.”
+(Lond. 1846. 4to.)
+
+3. “Voyage of H.M.S. Beagle. Fishes by _L. Jenyns_.” (Lond. 1842,
+4to.)
+
+4. “Voyage of H.M.S. Challenger. Fishes by _A. Günther_.” (in
+course of publication).
+
+
+                             C. _German._
+
+1. “Reise der österreichischen Fregatte Novara. Fische von _R.
+Kner_.” (Wien. 1865, 4to.)
+
+
+                             II.--FAUNAE.
+
+                          A. _Great Britain._
+
+1. _R. Parnell_, “The Natural History of the Fishes of the Firth
+of Forth.” (Edinb. 1838, 8vo.)
+
+2. _W. Yarrell_, “A History of British Fishes.” (3d edit. Lond.
+1859, 8vo.)
+
+3. _J. Couch_, “A History of the Fishes of the British Islands.”
+(Lond. 1862–5, 8vo.)
+
+
+                     B. _Denmark and Scandinavia._
+
+1. _H. Kröyer_, “Danmark’s Fiske.” (Kjöbnh. 1838–53, 8vo.)
+
+2. _S. Nilsson_, “Skandinavisk Fauna.” (Vol. IV. Fiskarna. Lund.
+1855, 8vo.)
+
+3. _Fries och Ekström_, “Skandinavians Fiskar.” (Stockh. 1836,
+4to, with excellent plates.)
+
+
+                             C. _Russia._
+
+1. _Nordmann_, “Ichthyologie Pontique,” in “Voyage dans la Russie
+méridionale de _Demidoff_.” (Tom. iii. Paris, 1840, 8vo, atlas
+fol.)
+
+
+                             D. _Germany._
+
+1. _Heckel_ and _Kner_, “Die Süsswasser-fische der
+Oesterreichischen Monarchie.” (Leipz. 1858, 8vo.)
+
+2. _C. T. E. Siebold_, “Die Süsswasser-fische von Mitteleuropa.”
+(Leipz. 1863, 8vo.)
+
+
+                     E. _Italy and Mediterranean._
+
+1. _Bonaparte_, “Iconografia della Fauna Italica.” Tom. iii.
+Pesci. (Roma, 1832–41, fol.) (Incomplete.)
+
+2. _Costa_, “Fauna del Regno di Napoli.” Pesci. (Napoli, 4to,
+about 1850.) (Incomplete.)
+
+
+                             F. _France._
+
+1. _E. Blanchard_, “Les Poissons des eaux douces de la France.”
+(Paris, 1866, 8vo.)
+
+
+                       G. _Pyrenean Peninsula._
+
+The freshwater Fish-fauna of Spain and Portugal was almost unknown,
+until _F. Steindachner_ paid some visits to those countries for
+the purpose of exploring the principal rivers. His discoveries are
+described in several papers in the “Sitzungsberichte der Akademie
+zu Wien.” _B. du Bocage_ and _F. Capello_ contributed towards the
+knowledge of the marine fishes on the coast of Portugal. (“Jorn.
+Scienc. Acad. Lisb.”)
+
+
+                          H. _North America._
+
+1. _J. Richardson_, “Fauna Boreali Americana.” Part III. Fishes.
+(Lond. 1836, 4to.) The species described in this work are nearly all
+from the British possessions in the North.
+
+2. _Dekay_, “Zoology of New York.” Part IV. Fishes. (New York,
+1842, 4to.)
+
+3. “Reports of the United States Commission of Fish and Fisheries.”
+(5 vols. Washingt. 1873–79, 8vo. In progress. Contains most valuable
+information.)
+
+Besides these works, numerous descriptions of North American freshwater
+fishes have been published in the Reports of the various U. S.
+Government expeditions, and in North American scientific journals, by
+_Storer_, _Baird_, _Girard_, _W. O. Ayres_, _Cope_, _Jordan_, _Brown
+Goode_, etc.; but a good general, and especially critical, account of
+the fishes of the United States is still a desideratum.
+
+
+                             I.--_Japan._
+
+1. “Fauna Japonica.” Poissons par _H. Schlegel_. (Lugd. Bat. 1850,
+fol.)
+
+
+J.--_East Indies; Tropical parts of the Indian and Pacific Oceans._
+
+1. _E. Rüppell_, “Atlas zu der Reise im Nördlichen Afrika.”
+(Frankf. 1828, fol.)
+
+2. _E. Rüppell_, “Neue Wirbelthiere. Fische.” (Frankf. 1837, fol.)
+
+These two works form the standard works for the student of the Fishes
+of the Red Sea, and are distinguished by a rare conscientiousness and
+faithfulness of the descriptions and figures; so that there is no
+other part of the tropical seas, with the fishes of which we are so
+intimately acquainted, as with those of the Red Sea. But these works
+have a still wider range of usefulness, in as much as only a small
+proportion of the fishes is limited to that area, the majority being
+distributed over the Indian Ocean into Polynesia. Rüppel’s works were
+supplemented by the two first of the following works:--
+
+3. _R. L. Playfair_ and _A. Günther_, “The Fishes of Zanzibar.” (Lond.
+1866, 4to); and
+
+4. _C. B. Klunzinger_, “Synopsis der Fische des Rothen Meers.”
+(Wien. 1870–1, 8vo.)
+
+5. _T. Cantor_, “Catalogue of Malayan Fishes.” (Calcutta, 1850,
+8vo.)
+
+6. _F. Day_, “The Fishes of India.” (Lond. 1875, 4to, in
+progress); contains an account of the freshwater and marine species,
+and is not yet complete.
+
+7. _A. Günther_, “Die Fische der Südsee.” (Hamburg, 4to; from
+1873, in progress.)
+
+Unsurpassed in activity, as regards the exploration of the fish fauna
+of the East Indian Archipelago, is _P. Bleeker_, a surgeon in the
+service of the Dutch East Indian Government (born 1819, died 1878),
+who, from the year 1840, for nearly thirty years, amassed immense
+collections of the fishes of the various islands, and described them
+in extremely numerous papers, published chiefly in the Journals of the
+Batavian Society. When his descriptions and the arrangement of his
+materials evoked some criticism, it must be remembered that, at the
+time when he commenced his labours, and for many years afterwards,
+he stood alone, without the aid of a previously named collection on
+which to base his first researches, and without other works but that
+of Cuvier and Valenciennes. He had to create for himself a method of
+distinguishing species and of describing them; and afterwards it would
+have been difficult for him to abandon his original method and the
+principles by which he had been guided for so many years. His desire
+of giving a new name to every individual, to every small assemblage
+of species wherever practicable, or of changing an old name, detracts
+not a little from the satisfaction with which his works would be
+used otherwise. It is also surprising that a man with his anatomical
+knowledge and unusual facilities should have been satisfied with the
+merely external examination of the specimens. But none of his numerous
+articles contain anything relating to the anatomy, physiology, or
+habits of the fishes which came under his notice; hence his attempts
+at systematic arrangement are very far from indicating an advance in
+Ichthyology.
+
+Soon after his return to Europe (1860) Bleeker commenced to collect the
+final results of his labours in a grand work, illustrated by coloured
+plates, “Atlas Ichthyologique des Indes Orientales Néerlandaises.”
+(Amsterd. fol. 1862); the publication of which was interrupted by the
+author’s death in 1878.
+
+
+                             K.--_Africa._
+
+1. _A. Günther_, “The Fishes of the Nile” in Petherick’s “Travels
+in Central Africa.” (Lond. 1869, 8vo.)
+
+2. _W. Peters_, “Naturwissenschaftliche Reise nach Mossambique.
+IV. Flussfische.” (Berl. 1868, 4to.)
+
+
+                 L.--_West Indies and South America._
+
+1. _L. Agassiz_, “Selecta genera et species Piscium, quæ in
+itinere per Brasiliam, collegit J. B. de Spix.” (Monach. 1829, fol.)
+
+2. _F. de Castlenau_, “Animaux nouveaux ou rares, recueillis
+pendant l’expedition dans les parties centrales de l’Amérique du Sud.
+Poissons.” (Paris, 1855, 4to.)
+
+3. _A. Günther_, “An account of the Fishes of the States of
+Central America.” (In Trans. Zool. Soc. 1868.)
+
+4. _L. Vaillant_ and _F. Bocourt_, “Mission scientifique au
+Mexique et dans l’Amérique centrale. Poissons.” (Paris, 1874, 4to.) (In
+progress.)
+
+_F. Poey_, the celebrated naturalist of Havannah, devoted many
+years of study to the Fishes of Cuba, His papers and memoirs are
+published partly in two periodicals, issued by himself, under the
+title of “Memorias sobre la Historia natural de la Isle de Cuba” (from
+1851), and “Repertorio Fisico-natural de la Isla de Cuba” (from 1865),
+partly in North American scientific journals. And, finally, _F.
+Steindachner_ has published many contributions, accompanied by
+excellent figures, to our knowledge of the Fishes of Central and South
+America.
+
+
+                          M.--_New Zealand._
+
+1. _F. W. Hutton_ and _J. Hector_, “Fishes of New Zealand.”
+(Wellingt. 1872, 8vo.)
+
+
+                         N.--_Arctic Regions._
+
+1. _G. Lütken_, “A revised Catalogue of the Fishes of Greenland,”
+in “Manual of the Natural History, Geology, and Physics of Greenland.”
+(Lond. 1875, 8vo.) Although only a nominal list, this catalogue is
+useful, as it contains references to all the principal works in which
+Arctic fishes have been described. The fishes of Spitzbergen were
+examined by _A. J. Malmgren_ (1865).
+
+
+                        III.--ANATOMICAL WORKS.
+
+The number of authors who worked on the anatomy of fishes is almost
+as great as that of faunists; and we should go beyond the limits of
+the present work if we mentioned more than the most prominent and
+successful. _M. H. Rathke_, _J. Müller_, _J. Hyrtl_, and _H. Stannius_
+left scarcely any organ unexamined, and their researches had a direct
+bearing either on the relation of the class of fishes to the other
+vertebrates, or on the systematic arrangement of the fishes themselves.
+_E. E. von Baer_, _F. de Filippi_, _C. Vogt_, _W. His_, _W. K. Parker_,
+and _F. M. Balfour_ worked at their embryology; _A. Kölliker_ and
+_G. Pouchet_ at their histology. The osteology was specially treated
+by _G. Bakker_, _F. C. Rosenthal_, _L. Agassiz_, and _C. Gegenbaur_;
+the nervous system by _Gottsche_, _Philipeaux_, _Stannius_, _L.
+de Sanctis_, _L. Stieda_, _Baudelot_ and _Miclucho-Maclay_; the
+organ of hearing by _E. H. Weber_, _C. Hasse_, and _G. Retzius_.
+The electric fishes were examined by _E. Geoffroy_, _C. Matteuci_,
+_P. Pacini_, _T. Bilharz_, and _Max Schultze_. The development and
+metamorphosis of the Lamperns was made the subject of research by _H.
+Müller_, _M. Schultze_, and _P. Owsjannikow_; Müller’s examination of
+_Branchiostoma_ was continued by _J. Marcusen_, _A. Kovalevsky_, _L.
+Stieda_, _W. Müller_, _C. Hasse_, _T. Huxley_, and _F. M. Balfour_. The
+most comprehensive accounts of the anatomy of fishes are contained in
+the following works:--
+
+1. _H. Stannius_, “Zootomic der Fische,” 2d edit. (Berl. 1854,
+8vo.)
+
+2. _R. Owen_, “Anatomy of Vertebrates,” vol. i. (Lond. 1866, 8vo.)
+
+3. _R. Owen_, “Lectures on the Comparative Anatomy and Physiology
+of the Vertebrate Animals.” Part I. Fishes. (Lond. 1846, 8vo.)
+
+4. _T. Huxley_, “A Manual of the Anatomy of Vertebrated Animals.”
+(Lond. 1871, 16mo.)
+
+       *       *       *       *       *
+
+[Sidenote: Latest Systematic Works.]
+
+It has been mentioned above that the great work of Cuvier and
+Valenciennes had been left incomplete. Several authors, therefore,
+supplied detailed accounts of the orders omitted in that work. _Müller_
+and _Henle_ published an account of the Plagiostomes, and _Kaup_ of
+the Murænidæ and Lophobranchii. _A. Duméril_, finally, commenced an
+“Histoire naturelle des Poissons ou Ichthyologie générale,” of which,
+however, two volumes only appeared, containing a complete account
+of the “Plagiostomes” (Paris, 1865, 8vo.), and of the “Ganoids and
+Lophobranchs.” (Paris, 1870, 8vo.)
+
+So great an activity had prevailed in Ichthyology since the publication
+of the “Histoire naturelle” by Cuvier and Valenciennes, and the results
+of the manifold enquiries were scattered over such a multitude of
+publications, that it became imperative to collect again all these
+materials in one comprehensive work. This was done in the “Catalogue
+of Fishes,” published by the Trustees of the British Museum, in eight
+volumes (Lond. 1859-70). Beside the species previously described
+many new forms were added, the number total of species referred
+to in those volumes amounting to 8525. As regards the systematic
+arrangement--Müller’s system was adopted in the main, but the
+definition of the families is much modified. This, however, need not be
+further entered into here, and will become sufficiently apparent in the
+subsequent parts of the present work.
+
+  [Illustration: Fig. 1.--Lower aspect of head of _Raia
+  lemprieri_.]
+
+
+
+
+                              CHAPTER II.
+
+      TOPOGRAPHICAL DESCRIPTION OF THE EXTERNAL PARTS OF FISHES.
+
+
+[Sidenote: Form of the body.]
+
+In the body of a fish four parts are distinguished: the _head_,
+_trunk_, _tail_, and the _fins_; the boundary between the first and
+second being generally indicated by the _gill-opening_, and that
+between the second and third by the _vent_. The form of the body and
+the relative proportions of those principal parts are subject to much
+variation, such as is not found in any other class of Vertebrates.
+In fishes which are endowed with the power of steady and more or
+less rapid locomotion, a deviation from that form of body, which we
+observe in a perch, carp, or mackerel, is never excessive. The body
+forms a simple, equally-formed wedge, compressed or slightly rounded,
+well fitted for cleaving the water. In fishes which are in the habit
+of moving on the bottom, the whole body, or at least the head, is
+_vertically depressed_ and flattened; the head may be so enormously
+enlarged that the trunk and tail appear merely as an appendage. In
+one family of fishes, the _Pleuronectidæ_ or Flat-fishes, the body is
+compressed into a thin disk; they swim and move on one side only, which
+remains constantly directed towards the bottom, a peculiarity by which
+the symmetry of all parts of the body has been affected. A _lateral
+compression_ of the body, in conjunction with a lengthening of the
+vertical and a shortening of the longitudinal axis, we find in fishes
+moving comparatively slowly through the water, and able to remain (as
+it were) suspended in it. This deviation from the typical form may
+proceed so far that the vertical axis greatly exceeds the longitudinal
+in length; generally all the parts of the body participate in this
+form, but in one kind of fish (the Sun-fish or _Orthagoriscus_) it is
+chiefly the tail which has been shortened, and reduced so much as to
+present the appearance of being cut off. An excessive lengthening of
+the longitudinal axis, with a shortening of the vertical, occurs in
+Eels and eel-like fishes, and in the so-called Band-fishes. They are
+bottom-fish, capable of insinuating themselves into narrow crevices and
+holes. The form of the body of these long fish is either cylindrical,
+snake-like, as in the Eels and many Cod-fishes, or strongly compressed
+as in the Band-fishes (_Trichiurus_, _Regalecus_, etc.) It is chiefly
+the tail which is lengthened, but frequently the head and trunk
+participate more or less in this form. Every possible variation
+occurs between these and other principal types of form. The old
+ichthyologists, even down to Linnæus, depended in great measure on them
+for classification; but although often the same form of body obtains
+in the same group of fishes, similarity of form by no means indicates
+natural affinity; it only indicates similitude of habits and mode of
+life.
+
+[Sidenote: Eye.]
+
+_The external parts of the Head._--The _Eye_ divides the head into the
+_ante-orbital_ and _post-orbital_ portion. In most fishes, especially
+in those with a compressed head, it is situated on the side and in the
+anterior half of the length of the head; in many, chiefly those with a
+depressed head, it is directed upwards, and sometimes situated quite
+at the upper side; in very few, the eyes look obliquely downwards. In
+the Flat-fishes both eyes are on the same side of the head, either the
+right or the left, always on that which is directed towards the light,
+and coloured.
+
+Fishes in general, compared with other Vertebrata, have large eyes.
+Sometimes these organs are enormously enlarged, their great size
+indicating that the fish is either nocturnal, or lives at a depth to
+which only a part of the sun’s rays penetrate. On the other hand, small
+eyes occur in fishes inhabiting muddy places, or great depths to which
+scarcely any light descends, or in fishes in which the want of an organ
+of sight is compensated by the development of other organs of sense.
+In a few fishes, more particularly in those inhabiting caves or the
+greatest depths of the ocean, the eyes have become quite rudimentary
+and hidden under the skin.
+
+[Sidenote: Snout.]
+
+In the _ante-orbital_ portion of the head, or the _Snout_, are situated
+the mouth and the nostrils.
+
+[Sidenote: Mouth.]
+
+The _Mouth_ is formed by the intermaxillary and maxillary bones, or by
+the intermaxillary only in the upper jaw, and by the mandibulary bone
+in the lower. These bones are either bare or covered by integument, to
+which frequently labial folds or lips are added. As regards form, the
+mouth offers as many variations as the body itself, in accordance with
+the nature of the food, and the mode of feeding. It may be narrow, or
+extremely wide and cleft to nearly the hind margin of the head; it may
+be semi-elliptical, semicircular, or straight in a transverse line;
+it may be quite in front of the snout (_anterior_), or at its upper
+surface (_superior_), or at its lower (_inferior_), or extending along
+each side _(lateral_); sometimes it is subcircular, organised for
+sucking. The jaws of some fishes are modified into a special weapon
+of attack (Sword-fish, Saw-fish); in fact, throughout the whole class
+of fishes the jaws are the only organ specialised for the purpose of
+attacking; weapons on other parts of the body are purely defensive.
+
+Both jaws may be provided with skinny appendages, _barbels_, which, if
+developed and movable, are sensitive organs of touch.
+
+[Sidenote: Nostrils.]
+
+In the majority of fishes the _Nostrils_ are a double opening on
+each side of the upper surface of the snout; the openings of each side
+being more or less close together. They lead into a shallow groove;
+and only in one family (the Myxinoids) perforate the palate. In this
+family, as well as in the Lampreys, the nasal aperture is single. In
+many Eels the openings are lateral, the lower perforating the upper
+lip. In the Sharks and Rays (Fig. 1, p. 34) they are at the lower
+surface of the snout, and more or less confluent; and, finally, in the
+Dipnoi and other Ganoids, one at least is within the labial boundary of
+the mouth.
+
+The space across the forehead, between the orbits, is called the
+_interorbital_ space; that below the orbit, the _infraorbital_ or
+_sub-orbital_ region.
+
+[Sidenote: Gill-cover.]
+
+In the _post-orbital_ part of the head there are distinguished, at
+least in most Teleosteous Fishes and many Ganoids, (Fig. 24) the
+_præoperculum_, a sub-semicircular bone, generally with a free and
+often serrated or variously-armed margin; the _operculum_, forming
+the posterior margin of the gill-opening, and the _sub-operculum_
+and _interoperculum_ along its inferior margin. All these bones,
+collectively called _opercles_, form the _gill-cover_, a thin bony
+lamella covering the cavity containing the gills. Sometimes they are
+covered with so thin a membrane that the single bones may be readily
+distinguished; sometimes they are hidden under a thick integument.
+In some cases the interoperculum is rudimentary or entirely absent
+(Siluroids).
+
+[Sidenote: Gill-opening.]
+
+The _Gill-opening_ is a foramen, or a slit behind or below the head,
+by which the water which has been taken up through the mouth for the
+purpose of breathing is again expelled. This slit may extend from
+the upper end of the operculum all round the side of the head to the
+symphysis of the lower jaw; or it may be shortened and finally reduced
+to a small opening on any part of the margin of the gill-cover.
+Sometimes (_Symbranchus_) the two openings, thus reduced, coalesce,
+and form what externally appears as a single opening only. The margin
+of the gill-cover is provided with a cutaneous fringe, in order to
+more effectually close the gill-opening; and this fringe is supported
+by one or several or many bony rays, the _branchiostegals_. The space
+on the chest between the two rami of the lower jaw and between the
+gill-openings is called the _isthmus_.
+
+  [Illustration: Fig. 2.--Head of _Mordacia mordax_, showing
+  the single nostril, and seven branchial openings.]
+
+The Sharks and Rays differ from the Teleosteous and Ganoid fishes in
+having five branchial slits (six or seven in _Hexanchus_ and
+_Heptanchus_), which are lateral in the Sharks, and at the lower
+surface of the head in the Rays (Fig. 1, p. 34). In Myxine only the
+gill-opening is at a great distance from the head; it is either single
+in this family (Cyclostomi), or there are six and more on each side
+(Fig. 2).
+
+[Sidenote: Tail.]
+
+In the _Trunk_ are distinguished the _back_, the _sides_, and the
+_abdomen_. It gradually passes in all fishes into the _Tail_; the
+termination of the abdominal cavity and the commencement of the tail
+being generally indicated by the position of the vent. The exceptions
+are numerous: not only certain abdominal organs, like the sexual, may
+extend to between the muscles of the tail, but the intestinal tract
+itself may pass far backwards, or, singularly, it may be reflected
+forwards, so that the position of the vent may be either close to the
+extremity of the tail or to the foremost part of the trunk.
+
+In many fishes the greater part of the tail is surrounded by the fins,
+leaving only a small portion (between dorsal, caudal, and anal fins)
+finless; this part is called the _free portion_ or the _peduncle_ of
+the tail.
+
+[Sidenote: Fins.]
+
+The _Fins_ are divided into _vertical_ or _unpaired_, and into
+_horizontal_ or _paired fins_. Any of them may be present or absent;
+and their position, number, and form are most important guides in
+determining the affinities of fishes.
+
+The _vertical_ fins are situated in the median dorsal line, from the
+head to the extremity of the tail, and in the ventral line of the
+tail. In fishes in which they are least developed or most embryonic,
+the vertical fin appears as a simple fold of the skin surrounding the
+extremity of the tail In its further progress of development in the
+series of fishes, it gradually extends more forwards, and may reach
+even the head and vent. Even in this embryonic condition the fin is
+generally supported by fine rays, which are the continuations of, or
+articulated to, other stronger rays supported by the processes or
+apophyses of the vertebral column. This form of the vertical fin is
+very common, for instance in the Eels, many Gadoid, Blennioid and
+Ganoid fishes in which, besides, the rays have ceased to be simple
+rods, showing more or less numerous joints (simple _articulated_
+rays; Fig. 3). _Branched_ rays are dichotomically split, the joints
+increasing in number towards the extremity.
+
+The continuity of the vertical fin, however, is interrupted in the
+majority of fishes; and three fins then are distinguished: one in the
+dorsal line--the _dorsal_ fin; one in the ventral line behind the
+anus--the _anal_ fin; and one confined to the extremity of the
+tail--the _caudal_ fin.
+
+  [Illustration: Fig. 3.
+
+    1. Simple ray.
+    2. Spine.
+    3. Simple articulated ray (soft).
+    4. Branched ray (soft).]
+
+
+The _caudal_ fin is rarely symmetrical, so that its upper half would
+be equal to its lower; the greatest degree of asymmetry obtains
+in fishes with heterocercal termination of the vertebral column
+(see subsequently, Figs. 31, 41). In fishes in which it is nearly
+symmetrical it is frequently prolonged into an upper and lower _lobe_,
+its hind margin being concave or more or less deeply excised; in others
+the hind margin is rounded, and when the middle rays greatly exceed in
+length the outer ones the fin assumes a pointed form.
+
+  [Illustration: Fig. 4.--Labrax lupus (Bass), an Acanthopterygian
+  with anterior spinous, and posterior soft dorsal fin.]
+
+Many and systematically important differences are observed
+in the _dorsal_ fin, which is either spiny-rayed (spinous)
+(_Acanthopterygian_), or soft-rayed (_Malacopterygian_). In the
+former, a smaller or greater number of the rays are simple and without
+transverse joints; they may be flexible, or so much osseous matter
+is deposited in them that they appear hard and truly spinous (Fig.
+3); these spines form always the anterior portion of the fin, which
+is detached from, or continuous with, the remaining jointed rays.
+The spines can be erected or depressed at the will of the fish; if
+in the depressed position the spines cover one another completely,
+their points lying in the same line, the fish is called _homacanth_;
+but if the spines are asymmetrical, alternately broader on one side
+than on the other, the fish is called _heteracanth_. The spinous
+division, as well as the one consisting of jointed rays, may again
+be subdivided. In the _Malacopterygian_ type all the rays remain
+jointed; indeed, sometimes the foremost ray, with its preceding short
+supports, is likewise ossified, and a hard spine, but the articulations
+can nearly always be distinctly traced. Sometimes the dorsal fin of
+Malacopterygian fishes is very long, extending from the head to the end
+of the tail, sometimes it is reduced to a few rays only, and in a few
+cases it is entirely absent. In addition to the rayed dorsal fin, many
+Malacopterygian fishes (as the Salmonoids, many Siluroids, Scopeloids,
+etc.) have another of greater or lesser extent, without any rays; and
+as always fat is deposited within this fold, it is called a _fatty_ fin
+(_pinna adiposa_).
+
+  [Illustration: Fig. 5.--Saurus undosquamis, a Malacopterygian
+  with anterior soft dorsal, and additional adipose fin.]
+
+The _anal_ fin is built on the same plan as the dorsal, and
+may be single or plural, long or short, or entirely absent; in
+Acanthopterygians its foremost rays are frequently simple and spinous.
+
+The _horizontal_ or _paired_ fins consist of two pairs: the pectorals
+and ventrals.
+
+The _pectoral_ fins (with their osseous supports) are the homologues of
+the anterior limbs of the higher Vertebrata. They are always inserted
+immediately behind the gill-opening; either symmetrical with a rounded
+posterior margin, or asymmetrical, with the upper rays longest and
+strongest; in Malacopterygians with a dorsal spine the upper pectoral
+ray is frequently developed into a similar defensive weapon.
+
+The _ventral_ fins are the homologues of the hind-limbs, and inserted
+on the abdominal surface, either behind the pectorals (_Pisces_ s.
+_Pinnæ abdominales_), or below them _(Pisces_ s. _Pinnæ thoracicæ_), or
+in advance of them (_Pisces_ s. _Pinnæ jugulares_). They are generally
+narrow, composed of a small number of rays, the outer of which is
+frequently osseous. In some small groups of fishes, like the Gobies,
+the fins coalesce and form a suctorial disk.
+
+  [Illustration: Fig. 6.--Salmo salar (Salmon), with abdominal
+  ventral fins.]
+
+  [Illustration: Fig. 7.--Mullus barbatus (Red Mullet), with
+  thoracic ventral fins.]
+
+  [Illustration: Fig. 8.--Burbot (Lota vulgaris), with jugular
+  ventral fins.]
+
+For the definition of the smaller systematic groups, and the
+determination of species, the numbers of the spines and rays are
+generally of the greatest importance. This holds good, especially
+for the ventral rays, by the number of which the Acanthopterygian
+affinities of a fish can nearly always be determined. The numbers of
+the dorsal and anal rays generally correspond to the number of vertebræ
+in a certain portion of the spine, and are therefore constant specific,
+generic, or even family characters; but when their number is very
+great, a proportionally wide margin must be allowed for variation, and
+the taxinomic value of this character becomes uncertain. The numbers of
+the pectoral and caudal rays are rarely of any account.
+
+[Sidenote: Function of the Fins.]
+
+The fins are organs of motion; but it is chiefly the tail and the
+caudal fin by which the fish impels itself forward. To execute
+energetic locomotion the tail and caudal fin are strongly bent,
+with rapidity, alternately towards the right and left; whilst a
+gentle motion forwards is effected by a simple undulating action of
+the caudal fin, the lobes of which act like the blades of a screw.
+Retrograde motions can be made by fish in an imperfect manner only,
+by forward-strokes of the pectoral fins. When the fish wants to
+turn towards the left, he gives a stroke of the tail towards the
+right, the right pectoral acting simultaneously, whilst the left
+remains ad-pressed to the body. Thus the pectoral fins assist in the
+progressive motions of the fish, but rather directing its course than
+acting as powerful propellers. The chief function of the paired fins is
+to maintain the balance of the fish in the water, which is always the
+most unsteady where there is no weight to sink it: when the pectoral
+of one side, or the pectoral and ventral of the same side are removed,
+the fish loses its balance and falls on the side opposite; when both
+pectorals are removed, the fish’s head sinks; on removal of the dorsal
+and anal fins the motion of the fish assumes a zig-zag course. A fish
+deprived of all fins, as well as a dead fish, floats with the belly
+upwards, the back being the heavier part of the body.
+
+In numerous groups of fishes which live in mud, or are enabled to pass
+a longer or shorter time in soil periodically dried and hardened
+during the hot season, forms occur entirely devoid of, or with only
+rudimentary, ventral fins (Cyprinodon, Ophiocephalidæ, Galaxiidæ,
+Siluridæ). The chief function of these fins being to balance the body
+of the fish whilst swimming, it is evident that in fishes moving during
+a great part of their life over swampy ground, or through more or less
+consistent mud, this function of the ventral fins ceases, and that
+nature can readily dispense with these organs altogether.
+
+  [Illustration: Fig. 9.--Ventrals of _Gobius_.]
+
+In certain fishes the shape and function of the fins are considerably
+modified: thus, in the Rays, locomotion is almost entirely effected
+and regulated by the broad and expanded pectoral fins acting with an
+undulatory motion of their margins, similar to the undulations of the
+long vertical fins of the Flat-fishes; in many Blennies the ventral
+fins are adapted for walking on the sea-bottom; in some Gobioids
+(_Periophthalmus_), Trigloids, Scorpænioids, and Pediculati, the
+pectoral fins are perfect organs of walking; in the Gobies, Cyclopteri,
+and Discoboli the ventral fins are transformed into an adhesive disk,
+and finally in the Flying-fish, in which the pectorals act as a
+parachute. In the Eels and other snake-like fishes, the swimming as
+well as the gliding motions are effected by several curvatures of the
+body, alternate towards the right and left, resembling the locomotion
+of Snakes. In the _Syngnathi_ (Pipe-fishes) and _Hippocampi_,
+whose body admits of but a slight degree of lateral curvature, and
+whose caudal fin is generally small, if present at all, locomotion is
+very limited, and almost wholly dependent on the action of the dorsal
+fin, which consists of a rapid undulating movement.
+
+  [Illustration: Fig. 10.--Cycloid scale of Gadopsis marmoratus
+  (magn.)]
+
+  [Illustration: Fig. 11.--Cycloid scale of Scopelus resplendens
+  (magn.)]
+
+[Sidenote: Skin and Scales.]
+
+The _skin_ of fishes is either covered with scales, or naked, or
+provided with more or less numerous scutes of various forms and sizes.
+Some parts, like the head and fins, are more frequently naked than
+scaly. All fishes provided with electric organs, the majority of Eels,
+and the Lampreys, are naked. _Scales_ of fishes are very different from
+those of Reptiles; the latter being merely folds of the cutis, whilst
+the scales of fishes are distinct horny elements, developed in grooves
+or pockets of the skin, like hairs, nails, or feathers. Very small
+or rudimentary scales are extremely thin, homogeneous in structure,
+and more or less imbedded in the skin, and do not cover each other.
+When more developed, they are imbricated (arranged in the manner of
+tiles), with the posterior part extruded and free, the surface of the
+anterior portion being usually covered by the skin to a greater or less
+extent. On their surface (Figs. 10 and 11) may be observed a very fine
+striation concentric and parallel to the margin, and coarser striæ
+radiating from a central point towards the hind margin. Scales without
+a covering of enamel, with an entire (not denticulated) posterior
+margin, and with a concentric striation, are called _Cycloid_ scales.
+_Ctenoid_ scales (Figs. 12–15) are generally thicker, and provided
+with spinous teeth on the posterior edges of the layers of which the
+scale consists. In some species only the layer nearest to the margin
+is provided with denticulations (Fig. 14). Scales, the free surface of
+which is spiny, and which have no denticulation on the margin, have
+been termed _Sparoid_ scales; but their distinction from ctenoid scales
+is by no means sharp, and there are even intermediate forms between
+the cycloid and ctenoid types. Both kinds of scales may occur not only
+in species of the same genus of fishes, but in the same fish.
+
+  [Illustration: Fig. 12.--Ctenoid scale of Scatophagus
+  multifasciatus (magn.)]
+
+  [Illustration: Fig. 13.--Ctenoid scale of Platycephalus
+  cirrhonasus (magn.)]
+
+  [Illustration: Fig. 14.--Ctenoid scale of Gobius ommaturus
+  (magn.)]
+
+  [Illustration: Fig. 15.--Ctenoid scale of Lethrinus (magn.)]
+
+  [Illustration: Fig. 16. Ganoid Scales.]
+
+_Ganoid_ scales are hard and bony, covered with a layer of enamel; they
+are generally rhombic or quadrangular, rarely rounded and imbricate;
+and arranged in oblique rows, those of one row being linked together
+by an articulary process. This type of scales, common in fossil Ganoid
+fishes, occurs among recent fishes in _Lepidosteus_ and _Polypterus_
+only.
+
+Finally, in Sharks, the Balistidæ, and others, true scales are absent
+and replaced by the ossified papillæ of the cutis, which give the
+surface the appearance of fine-grained chagreen. These generally small
+bodies, as well as the large osseous scutes of the Rays, Sturgeons,
+etc., have been comprised under the common name _Placoid_ scales; a
+term which deservedly is being abandoned.
+
+  [Illustration: Fig. 17.--Dermal papillæ of Monacanthus trossulus.]
+
+  [Illustration: Fig. 18.--Dermal papillæ of Monacanthus
+  hippocrepis (magn.)]
+
+  [Illustration: Fig. 19.--Cycloid scale from the lateral line of
+  Odax lineatus (magn.)]
+
+Along the side of the body of osseous fishes runs a series of
+perforated scales, which is called the _lateral line_ (Fig. 21).
+The perforating duct is simple at its base, and may be also simple at
+its outer opening (Fig. 19), or (and this is frequently the case) the
+portion on the free surface of the scale is ramified (Fig. 20). The
+lateral line runs from the head to the tail, sometimes reaching the
+caudal fin, sometimes stopping in front of it, sometimes advancing over
+its rays. It is nearer to the dorsal profile in some fishes than in
+others. Some species have several lateral lines, the upper one coasting
+the dorsal, the lower the abdominal outline, one running along the
+middle as usual. The scales of the lateral line are sometimes larger
+than the others, sometimes smaller, sometimes modified into scutes,
+sometimes there are no other scales beside them, the rest of the body
+being naked. The foramina of the lateral line are the outlets of a
+muciferous duct which is continued on to the head, running along the
+infraorbital bones, and sending off a branch into the præopercular
+margin and mandible. In many fishes, as in many Sciænoids, Gadoids,
+and in numerous deep-sea fishes, the ducts of this muciferous system
+are extraordinarily wide, and generally filled with mucus, which
+is congealed or contracted in specimens preserved in spirits, but
+swells again when the specimens are immersed in water. This system is
+abundantly provided with nerves, and, therefore, has been considered
+to be the seat of a sense peculiar to fishes, but there cannot be any
+doubt that its function is the excretion of mucus, although probably
+mucus is excreted also from the entire surface of the fish.
+
+  [Illustration: Fig. 20.--Cycloid scale from the lateral line of
+  Labrichthys laticlavius (magn.)]
+
+The scales, their structure, number and arrangement, are an important
+character for the determination of fishes; in most scaly fishes they
+are arranged in oblique transverse series; and as the number of scales
+in the lateral line generally corresponds to the number of transverse
+series, it is usual to count the scales in that line. To ascertain
+the number of longitudinal series of scales, the scales are counted
+in one of the transverse series, generally in that running from the
+commencement of the dorsal fin, or the middle of the back to the
+lateral line, and from the lateral line down to the vent or ventral
+fin, or middle of the abdomen.[4]
+
+  [Illustration: Fig. 21.--Arrangement of scales in the Roach
+  (Leuciscus ratilus): _Ll_ = Lateral line; _tr_ =
+  Transverse line. _a_, Transverse line from lateral line to
+  ventral fin.]
+
+The scales of many fishes are modified for special purposes, especially
+to form weapons of defence or a protective armour, but the details of
+such modifications are better mentioned under the several families in
+which they occur. All scales are continually growing and wasting away
+on the surface, and it seems that some fish, at least,--for instance,
+Salmonoids--“shed” them periodically; during the progress of this
+shedding the outlines of the scales are singularly irregular.
+
+
+
+
+                             CHAPTER III.
+
+              TERMINOLOGY AND TOPOGRAPHY OF THE SKELETON.
+
+
+In order to readily comprehend the subsequent account of the
+modifications of the skeleton in the various sub-classes and groups of
+Fishes, the student has to acquaint himself with the terms used for the
+numerous bones of the fish skeleton, as well as with their relative
+position. The skeleton of any of the more common kinds of osseous fish
+may serve for this purpose; that of the Perch is chosen here.
+
+The series of bones constituting the axis of the body, and destined to
+protect the spinal chord and some large longitudinal blood-vessels, is
+called the _vertebral_ or _spinal column_; the single bones are the
+_vertebræ_. The _skull_ consists of the bones surrounding the brain
+and organs of sense, and of a number of arches suspended from it, to
+support the commencement of the alimentary canal and the respiratory
+organs.
+
+The _vertebra_ (Fig. 22) consists of a body or _centrum_ (_c_), with
+a concave anterior and posterior surface, and generally of several
+_processes_ or _apophyses_, as--1. Two _neurapophyses_ (_na_), which,
+on the dorsal side, rising upwards, form the _neural arch_ over the
+canal, in which the spinal chord is lodged. 2. Two _parapophyses_
+(_pa_) usually projecting from the lower part of the sides of the body,
+or two _hæmapophyses_ (_ha_) which actually coalesce to form on the
+ventral side the hæmal canal for a large trunk of the vascular system.
+3. A _neural spine_ (_ns_), which crowns the neurapophyses, or is
+interposed between their tips. 4. A _hæmal spine_ (_hs_), having the
+same relation to the hæmapophyses. 5. Two _pleurapophyses_ or floating
+_ribs_, suspended from, or from the base of, the parapophyses. 6. In
+most fishes the neural arches are connected together by articular or
+oblique processes, _zygapophyses_ (_za_), which are developed from the
+base of each neurapophysis.
+
+  [Illustration: Fig. 22.--Side and Front view of Fish-vertebra.]
+
+The vertebræ are either _abdominal_ or _caudal_ vertebræ, the
+coalescence of the parapophyses into a complete hæmal ring, and the
+suspension of the anal fin generally forming a sufficiently well-marked
+boundary between abdominal and caudal regions (Fig. 23). In the Perch
+there are twenty-one abdominal and as many caudal vertebræ. The centrum
+of the first vertebra or atlas is very short, with the apophyses
+scarcely indicated, and lacking ribs like the succeeding vertebra. All
+the other abdominal vertebræ, with the exception of the last or two
+last, are provided with ribs, many of which are bifid (72). A series of
+flat spines (74), called _interneurals_, to which the spines and rays
+of the dorsal fins are articulated, are supported by the neural spines,
+the strength of the neurals and interneurals corresponding to that of
+the _dermal_ spines (75). The caudal vertebræ differ from the abdominal
+in having the hæmapophyseal elements converted into spines similar to
+the neurals, the anterior being likewise destined to support a series
+of _interhæmals_ (79), to which the anal rays are articulated. The
+last and smallest caudal vertebra articulates with the _hypural_ (70),
+a fan-like bone, which, together with the dilated hindmost neural and
+hæmal elements, supports the caudal rays.
+
+Looking at a perch’s _skull_ from the side (Fig. 24), the most
+superficial bones will be found to be those of the jaws, a chain of
+thin bones round the lower half of the eye, and the opercles.
+
+The anterior margin of the upper jaw is formed by the _intermaxillary_
+or _premaxillary_ (17) which bears teeth, terminates in a pedicle
+above, to allow of a forward sliding motion of the jaw, and is dilated
+into a flat triangular process behind, on which leans the second
+bone of the upper jaw, the _maxillary_ (18). This bone is toothless,
+articulates with the vomer and palatine bone, and is greatly dilated
+towards its distal extremity. Both the maxillary and intermaxillary
+lie and move parallel to each other, being connected by a narrow
+membrane; in many other fishes their relative position is very
+different.
+
+The _mandible_ or lower jaw consists of a right and left ramus;
+their union by a ligament in front is called _symphysis_. Each ramus
+is formed of several pieces; that which, by a sigmoid concavity
+articulates with the quadrate, is the _articulary_ bone (35); it sends
+upwards a coronoid process, to which a ligament from the maxillary
+and the masticatory muscles are attached; and forwards a long-pointed
+process, to be sheathed in the deep notch of the anterior piece. A
+small separate piece (36) at the lower posterior angle of the mandible
+is termed _angular_. The largest piece (34) is tooth-bearing, and hence
+termed _dentary_; at its inner surface it is always deeply excavated,
+to receive a cylindrical cartilage, called _Meckel’s cartilage_, the
+remains of an embryonic condition of the jaw, the articulary and
+angular being but ossified parts of it. In other _Teleostei_ this
+number is still more increased by a _splenial_ and other bones.
+
+The _infraorbital_ ring of bones (Fig. 23, ^{19}) consists of several
+(four) pieces, of which the anterior is the largest, and distinguished
+as _præorbital_.
+
+The so-called _præoperculum_ (30) belongs rather to the bones of the
+suspensorium of the mandible, presently to be described, than to the
+opercles proper. It is narrow, strong, angularly bent, so as to consist
+of a vertical and horizontal limb, with an incompletely closed canal
+running along both limbs. As it is quite a superficial bone, and
+frequently armed with various spines, its form and configuration form
+an important item in the descriptive details of many fishes.
+
+The principal piece of the gill-cover is the _operculum_ (28),
+triangular in shape, situated behind, and movably united with, the
+vertical limb of the præoperculum. There is an articulary cavity at
+its upper anterior angle for its junction with the hyomandibular. The
+oblong lamella below the operculum is the _sub-operculum_ (32), and
+the one in front of this latter, below the horizontal limb of the
+præoperculum, is the _interoperculum_ (33), which is connected by
+ligament with the angular piece of the lower jaw, and is also attached
+to the outer face of the hyoid, so that the gill-covers cannot open or
+shut without the hyoid apparatus executing a corresponding movement.
+
+The chain of flat bones which, after the removal of the temporal
+muscles, appear arranged within the inner concavity of the præoperculum
+(Fig. 24), are comprised with the latter under the common name of
+_mandibulary suspensorium_. They connect the mandible with the
+cranium. The uppermost, the _epitympanic_ or _hyomandibular_ (23), is
+articulated by a double articulary head with the mastoid and posterior
+frontal. Another articulary head is destined for the opercular joint.
+The _mesotympanic_ or _symplectic_ (31) appears as a styliform
+prolongation of the lower part of the hyomandibular; is entirely
+cartilaginous in the young, but nearly entirely ossified in the adult.
+The position of this bone is noteworthy, because, directly inwards of
+its cartilaginous junction with the hyomandibular, there is situated
+the uppermost piece of the hyoid arch, the stylohyal. The next bone of
+the series is the _pretympanic_ or _metapterygoid_ (27), a flat bone
+forming a bridge towards the pterygoid, and not rarely absent in the
+teleosteous sub-class. Finally, the large triangular _hypo-tympanic_ or
+_quadrate_ (26) has a large condyle for the mandibulary joint.
+
+The palatine arch (Fig. 26) connects the suspensorium with the
+anterior extremity of the skull, and is formed by three bones: the
+_entopterygoid_ (25), an oblong and thin bone attached to the inner
+border of the palatine and pterygoid, and increasing the surface of
+the bony roof of the mouth towards the median line; it constitutes
+also the floor of the orbit. The _pterygoid_ (24) (or _os transversum_)
+starts from the quadrate, and is joined by suture to the _palatine_,
+which is toothed, and reaches to the vomer and anterior frontal.
+
+In the occipital region there are distinguished the _basi-occipital_
+(5), readily recognised by the conical excavation corresponding and
+similar to that of the atlas, with which it is articulated through
+the intervention of a capsule filled with a gelatinous substance (the
+remains of the notochord); the _exoccipitals_ (10), articulated, one on
+each side, to the basi-occipital, and expanding on the upper surface of
+that bone, so as to meet and support the spinal column; a superficial
+thin lamella (13), suturally connected with the exoccipitals,
+not constant in fishes, and erroneously believed by Cuvier to be
+the _petrosal_ (_os petrosum_) of higher animals; further, the
+_paroccipitals_ (9), which are wedged in between the exoccipitals and
+_supraoccipital_. This last bone (8) forms the key of the arch over the
+occipital foramen, and raises a strong high crest from the whole length
+of its mesial line; a transverse supraoccipital ridge, coming from each
+side of the base of this spine runs outwards laterally to the external
+angles of the bone. The supraoccipital separates the parietals, and
+forms a suture with the frontals.
+
+In front of the basi-occipital the base of the skull is formed by the
+_basisphenoid_ (_parasphenoid_ of Huxley) (6). This very long and
+narrow bone extends from the basi-occipital beyond the brain-capsule to
+between the orbits, where it forms the support of the fibro-membranous
+interorbital septum. Anteriorly it is connate with another long
+hammer-shaped bone (16), the _vomer_, the head of which marks the
+anterior end of the palate, and is beset with teeth. The _alisphenoids_
+(11) are short broad bones, rising from the basisphenoid; their
+posterior margins are suturally connected with the anterior of the
+basi- and exoccipitals.
+
+  [Illustration: Fig. 23.--Skeleton of the Perch.]
+
+  [Illustration: Fig. 24.--Skeleton of a Perch’s Skull.]
+
+  [Illustration: Fig. 25.--Hyoid arch, branchial apparatus, and
+  scapulary arch of the Perch.]
+
+  [Illustration: Fig. 26.--Lower view of Skull of Perch.]
+
+  [Illustration: Fig. 27.--Hyoid bone of the Perch.]
+
+The formation of the posterior part of the side of the skull is
+completed by the _mastoid_ and _parietal_ bones. The former (12)
+projects outwards and backwards farther than the paroccipital, forming
+the outer strong process of the side of the cranium. This process
+lodges on its upper surface one of the main ducts of the muciferous
+system, and affords the base of articulation to a part of the
+hyomandibular. Its extremity gives attachment to the strong tendon of
+the dorso-lateral muscles of the trunk. The _parietals_ (7) are flat
+bones, of comparatively much smaller extent than in higher Vertebrates,
+and separated from each other by the anterior prolongation of the
+supraoccipital.
+
+The anterior wall of the brain-capsule (or the posterior of the orbit)
+is formed by the _orbitosphenoids_ (14), between which, superiorly,
+the olfactory nerves, and inferiorly, the optic, pass out of the
+cranium. In addition to this paired bone, the Perch and many other
+fishes possess another single bone (15),--the _os sphenoideum anterius_
+of Cuvier, _ethmoid_ of Owen, and _basisphenoid_ of Huxley; it is
+Y-shaped, each lateral branch being connected with an orbito-sphenoid,
+whilst the lower branch rests upon the long basal bone.
+
+A cartilage, the substance of which is thickest above the vomer,
+and which extends as a narrow stripe along the interorbital septum,
+represents the _ethmoid_ of higher Vertebrata; the olfactory nerves run
+along, and finally perforate it.
+
+There remain, finally, the bones distinguishable on the upper surface
+of the skull; the largest, extending from the nasal cavities to the
+occipital, are the _frontal_ bones (1), which also form the upper
+margin of the orbit. The _postfrontals_ (4) are small bones placed
+on the supero-posterior angle of the orbit, and serving as the point
+from which the infraorbital ring is suspended. The _pre-frontals_ (2),
+also small, occupy the anterior margin of the orbit. A pair of small
+tubiform bones (20), the _turbinals_, occupy the foremost part of the
+snout, in front of the frontals, and are separated from each other by
+intervening cartilage.
+
+After removal of the gill-cover and mandibulary suspensorium, the hyoid
+arch, which encloses the branchial apparatus, and farther behind,
+the humeral arch are laid open to view (Fig. 25). These parts can be
+readily separated from the cranium proper.
+
+The _hyoid arch_ is suspended by a slender styliform bone, the
+_stylohyal_ (29), from the hyomandibulars; it consists of three
+segments, the _epihyal_ (37), _ceratohyal_ (38), which is the longest
+and strongest piece, and the _basihyal_, which is formed by two
+juxtaposed pieces (39, 40). Between the latter there is a median
+styliform ossicle (41), extending forwards into the substance of the
+tongue, called _glossohyal_ or _os linguale_; and below the junction of
+the two hyoid branches there is a vertical single bone (42), expanded
+along its lower edge, which, connected by ligament with the anterior
+extremity of the humeral arch, forms the _isthmus_ separating the
+two gill-openings. This bone is called the _urohyal_. Articulated or
+attached by ligaments to the epihyal and ceratohyal are a number of
+sword-shaped bones or rays (43), the _branchiostegals_, between which
+the branchiostegal membrane is extended.
+
+The _branchial arches_ (Figs. 25 and 27) are enclosed within the hyoid
+arch, with which they are closely connected at the base. They are five
+in number, of which four bear gills, whilst the fifth (56) remains
+dwarfed, is beset with teeth, and called the _lower pharyngeal_ bone.
+The arches adhere by their lower extremities to a chain of ossicles
+(53, 54, 55), _basibranchials_, and, curving as they ascend, nearly
+meet at the base of the cranium, to which they are attached by a
+layer of ligamentous and cellular tissue. Each of the first three
+branchial arches consists of four pieces movably connected with one
+another. The lowest is the _hypobranchial_ (57), the next much longer
+one (58) the _cerato-branchial_, and, above this, a slender and a
+short irregularly-shaped _epibranchial_ (61). In the fourth arch
+the hypobranchial is absent. The uppermost of these segments (62),
+especially of the fourth arch, are dilated, and more or less confluent;
+they are beset with fine teeth, and generally distinguished as the
+_upper pharyngeal bones_. Only the cerato-branchial is represented in
+the fifth arch or lower pharyngeal. On their outer convex side the
+branchial segments are grooved for the reception of large blood-vessels
+and nerves; on the inner side they support horny processes (63), called
+the _gill-rakers_, which do not form part of the skeleton.
+
+The _scapular_ or _humeral arch_ is suspended from the skull by the
+(_suprascapula_) _post-temporal_ (46), which, in the Perch, is attached
+by a triple prong to the occipital and mastoid bones. Then follows the
+(_scapula_) _supraclavicula_ (47), and the arch is completed below
+by the union of the large (_coracoid_) _clavicula_ (48) with its
+fellow. Two flat bones (51, 52), each with a vacuity, attached to the
+clavicle have been determined as the (_radius_ and _ulna_) _coracoid_
+and _scapula_ of higher vertebrates, and the two series of small
+bones (53) intervening between the forearm and the fin as _carpals_
+and _metacarpals_. A two-jointed appendage the (_epicoracoid_)
+_postclavicula_, is attached to the clavicle: its upper piece (49) is
+broad and lamelliform, its lower (50) styliform and pointed.
+
+The ventral fins are articulated to a pair of flat triangular bones,
+the _pubic_ bones (80).
+
+The bones of the skull of the fish have received so many different
+interpretations that no two accounts agree in their nomenclature,
+so that their study is a matter of considerable difficulty to the
+beginner. The following synonymic table will tend to overcome
+difficulties arising from this cause; it contains the terms used
+by Cuvier, those introduced by Owen, and finally the nomenclature
+of Stannius, Huxley, and Parker. Those adopted in the present work
+are printed in italics. The numbers refer to the figures in the
+accompanying woodcuts (Figs. 23–27).
+
+        _Cuvier._          _Owen._             _Stannius._       _Huxley, Parker,
+                                                                       etc._
+
+  1. Frontal principal   _Frontal_           Os frontale
+  2. Frontal antérieur   _Prefrontal_        Os frontale         Lateral ethmoid
+                                               anterius            (Parker)
+  3. _Ethmoid_             Nasal             Os ethmoideum
+  4. Frontal              _Postfrontal_      Os frontale         Sphenotic
+       postérieur                              posterius           (Parker)
+  5. Basilaire            _Basioccipital_    Os basilare
+  6. Sphénoide            _Basisphenoid_     Os sphenoideum      Sometimes referred
+                                               basilare            to as “_Basal_”
+  7. Pariétal             _Parietal_         Os parietale
+  8. Interpariétal or     _Supraoccipital_   Os occipitale
+       occipital                               superius
+       supérieure
+  9. Occipital externe    _Paroccipital_     Os occipitale       Epioticum
+                                               externum            (Huxley)
+ 10. Occipital lateral    _Exoccipital_      Os occipitale
+                                               laterale
+ 11. Grande aile du       _Alisphenoid_      Ala temporalis      Prooticum
+       sphénoide                                                   (_Huxley_)
+ 12. Mastoidien           _Mastoid_          Os mastoideum       {
+                                             + os extrascapulare {Opisthoticum[5]
+                                                                 {  +_Squamosal_
+ 13. Rocher               Petrosal and       Oberflächliche      {  (Huxley)
+                            Otosteal           Knochen-lamelle   {
+ 14. Aile orbitaire       _Orbitosphenoid_   Ala orbitalis       Alisphenoid
+                                                                   (Huxley)
+ 15. Sphenoide            Ethmoid and        Os sphenoideum      _Basisphenoid_
+       antérieur            Ethmoturbinal      anterius            (Huxley)
+ 16. _Vomer_              Vomer              Vomer
+ 17. Intermaxillaire      _Inter- or Pre-    Os intermaxillare
+                            maxillary_
+ 18. Maxillaire           _Maxillary_        Os maxillare
+       supérieur
+ 19. Sousorbitaires       _Infraorbital      Ossa
+                            ring_              infraorbitalia
+ 20. Nasal                _Turbinal_         Os terminale
+ 22. Palatine             _Palatin_          Os palatinum
+ 23. Temporal             Epitympanic        Os temporale        _Hyomandibular_
+                                                                   (Huxley)
+ 24. Transverse           _Pterygoid_        Os transversum
+                                               s. pterygoideum
+                                               externum
+ 25. Ptérygoidien         _Entopterygoid_    Os pterygoideum     Mesopterygoid
+        interne                                                    (Parker)
+ 26. Jugal                Hypotympanic       Os quadratojugale   _Quadrate_
+                                                                   (Huxley)
+ 27. Tympanal             Pretympanic        Os tympanicum       _Metapterygoid_
+                                                                   (Huxley)
+ 28. Operculaire          _Operculum_        Operculum
+ 29. Styloide             _Stylohyal_        Os styloideum
+ 30. Préopercule          _Præoperculum_     Præoperculum
+ 31. Symplectique         Mesotympanic       _Os symplecticum_
+ 32. Sousopercule         _Suboperculum_     Suboperculum
+ 33. Interopercule        _Interoperculum_   Interoperculum
+ 34. Dentaire             _Dentary_          Os dentale
+ 35. Articulaire          _Articulary_       Os articulare
+ 36. Angulaire            _Angular_          Os angulare
+ 37. } Grandes pièces     _Epihyal_         }
+ 38. }   latérales        _Ceratohyal_      } Segmente der
+                                            }   Zungenbein-
+ 39. } Petites pièces     _Basihyal_        }   Schenkel
+ 40. }   laterales                          }
+ 41. Os lingual           _Glossohyal_       Os linguale s.
+                                               entoglossum
+ 42. Queue de l’os hyoide _Urohyal_                              Basibranchiostegal
+                                                                      (Parker)
+ 43. Rayon branchiostège  _Branchiostegal_   Radii branchio-
+                                               stegi
+ 46. Surscapulaire        Suprascapula       Omolita             _Post-temporal_
+                                                                    (Parker)
+ 47. Scapulaire           Scapula            Scapula             _Supraclavicula_
+                                                                    (Parker)
+ 48. Humeral              Coracoid           Clavicula           _Clavicula_
+                                                                    (Parker)
+ 49. } Coracoid           Epicoracoid                            _Postclavicula_
+ 50. }                                                              (Parker)
+ 51. Cubital              Radius            } Ossa carpi         _Coracoid_ (Parker)
+ 52. Radial               Ulna              }                    _Scapula_ (Parker)
+ 53. Os du carpe          _Carpals_          Ossa metacarpi    { _Basalia_ (Huxley),
+                                                               { Brachials (Parker)
+ 53 bis. }
+ 54.     } Chaine intermédiaire _Basibranchials_  Copula
+ 55.     }
+ 56. Pharyngiens          _Lower_            Ossa pharyngea
+      inférieurs            _Pharyngeals_      inferiora
+ 57. Pièce interne de     _Hypobranchial_        }
+      partie inférieure                          }
+      de l’arceau                                }
+      branchiale                                 }
+ 58. Pièce externe  „     _Ceratobranchial_      } Segmente der
+ 59. Stylet de prémière   _Upper epibranchial_   }   Kiemenbogen-
+       arceau branchiale    _of first branchial_ }   Schenkel
+                            _arch_               }
+ 61. Partie supérieure    _Epibranchials_        }
+        de l’arceau                              }
+        branchiale                               }
+ 62. Os pharyngian        Pharyngo-          Os pharyngeum       _Upper pharyngeals_
+       supérieur            branchial          superius
+ 63.                      _Gill-rakers_
+ 65. Rayons de la         _Pectoral rays_    Brustflossen-
+       pectorale                               Strahlen
+ 67, 68. Vertèbres        _Abdominal         Bauchwirbel
+           abdominales      vertebræ_
+ 69. Vertèbres caudales   _Caudal vertebræ_  Schwanzwirbel
+
+ 70. Plaque triangulaire  [Aggregated        Verticale Platte    _Hypural_(Huxley)
+        et verticale           interhæmals]
+ 71.                       _Caudal rays_     Schwanzflossen
+                                               Strahlen
+ 72. Côte                  _Rib_             Rippen
+ 73. Appendices or        _Epipleural        Muskel-Gräthen
+       stylets              spines_
+ 74. Interépineux         _Interneural       Ossa interspinalia
+                            spines_            s. obere
+                                               Flossentræger
+ 75. Épines et rayons     _Dorsal rays and_  Rückenflossen-Strahlen
+           dorsales         _spines_           u. Stacheln
+ 76.                      _First
+                            interneural_
+ 78.                      _Rudimentary_
+                             _caudal rays_
+ 79. Apophyses épineuses  _Interhæmal        Untere Flossentræger
+           inférieures      spines_
+ 80.                      _Pubic_            Becken
+ 81.                      _Ventral spine_    Bauchflossen-Stachel
+
+
+
+
+                              CHAPTER IV.
+
+                    MODIFICATIONS OF THE SKELETON.
+
+
+The lowermost sub-class of fishes, which comprises one form only, the
+Lancelet (_Branchiostoma_ [s. _Amphioxus_] _lanceolatum_), possesses
+the skeleton of the most primitive type.
+
+  [Illustration: Fig. 28.--Branchiostoma lanceolatum. _a_,
+  Mouth; _b_, Vent; _c_, abdominal porus.]
+
+  [Illustration: Fig. 29.--Anterior end of body of Branchiostoma
+  (magn.) _d_, Chorda dorsalis; _e_, Spinal chord; _f_,
+  Cartilaginous rods; _g_, Eye; _h_, Branchial rods; _i_, Labial
+  cartilage; _k_, Oral cirrhi.]
+
+The vertebral column is represented by a simple _chorda_ _dorsalis_
+or _notochord_ only, which extends from one extremity of the fish to
+the other, and, so far from being expanded into a cranial cavity,
+it is pointed at its anterior end as well as at its posterior. It is
+enveloped in a simple membrane like the spinal chord and the abdominal
+organs, and there is no trace of vertebral segments or ribs; however, a
+series of short cartilaginous rods above the spine evidently represent
+apophyses. A maxillary or hyoid apparatus, or elements representing
+limbs, are entirely absent.
+
+   [J. Müller, Ueber den Bau und die Lebenserscheinungen des
+   _Branchiostoma lubricum_, in Abhandl. Ak. Wiss. Berlin,
+   1844.]
+
+The skeleton of the _Cyclostomata_ (or Marsipobranchii) (Lampreys and
+Sea-hags) shows a considerable advance of development. It consists of
+a notochord, the anterior pointed end of which is wedged into the base
+of a cranial capsule, partly membranous partly cartilaginous. This
+skull, therefore, is not movable upon the spinal column. No vertebral
+segmentation can be observed in the notochord, but neural arches are
+represented by a series of cartilages on each side of the spinal chord.
+In _Petromyzon_ (Fig. 30) the basis cranii emits two prolongations on
+each side: an inferior, extending for some distance along the lower
+side of the spinal column, and a lateral, which is ramified into a
+skeleton supporting the branchial apparatus. A stylohyal process and a
+subocular arch with a palato-pterygoid portion may be distinguished.
+The roof of the cranial capsule is membranous in _Myxine_ and in the
+larvæ of _Petromyzon_, but more or less cartilaginous in the adult
+_Petromyzon_ and in _Bdellostoma_. A cartilaginous capsule on each side
+of the hinder part of the skull contains the auditory organ, whilst the
+olfactory capsule occupies the anterior upper part of the roof. A broad
+cartilaginous lamina, starting from the cranium and overlying part
+of the snout, has been determined as representing the ethmo-vomerine
+elements, whilst the oral organs are supported by large, very peculiar
+cartilages (_labials_), greatly differing in general configuration
+and arrangement in the various Cyclostomes. There are three in the
+Sea-lamprey, of which the middle one is joined to the palate by an
+intermediate smaller one; the foremost is ring-like, tooth-bearing,
+emitting on each side a styliform process. The lingual cartilage is
+large in all Cyclostomes.
+
+There is no trace of ribs or limbs.
+
+   [J. Müller, Vergleichende Anatomie der Myxinoiden. Erster Theil.
+   Osteologie und Myologie, in Abhandl. Ak. Wiss. Berlin, 1835.]
+
+  [Illustration: Fig. 30.--Upper (A) and side (B) views, and
+  vertical section (C) of the skull of _Petromyzon marinus_.
+
+    _a_, Notochord; _b_, Basis cranii; _c_, Inferior, and _d_,
+    Lateral process of basis; _e_, Auditory capsule; _f_,
+    Subocular arch; _g_, Stylohyal process; _h_, Olfactory
+    capsule; _i_, Ethmo-vomerine plate; _k_, Palato-pterygoid
+    portion of subocular arch; _l-n_, Accessory labial or rostral
+    cartilages; with _o_, appendage; _p_, lingual cartilage;
+    _q_, neural arches; _r_, Branchial skeleton; _s_, Blind
+    termination of the nasal duct between the notochord and
+    œsophagus.]
+
+  [Illustration: Fig. 31.--Heterocercal Tail of Centrina salviani.
+  _a_, Vertebræ; _b_, Neurapophyses; _c_,
+  Hæmapophyses.]
+
+The _Chondropterygians_ exhibit a most extraordinary diversity in
+the development of their vertebral column; almost every degree of
+ossification, from a notochord without a trace of annular structure to
+a series of completely ossified vertebræ being found in this order.
+Sharks, in which the notochord is persistent, are the _Holocephali_
+(if they be reckoned to this order, and the genera _Notidanus_ and
+_Echinorhinus_). Among the first, _Chimæra monstrosa_ begins to show
+traces of segmentation; but they are limited to the outer sheath of the
+notochord, in which slender subossified rings appear. In _Notidanus_
+membranous septa, with a central vacuity, cross the substance of the
+gelatinous notochord. In the other Sharks the segmentation is complete,
+each vertebra having a deep conical excavation in front and behind,
+with a central canal through which the notochord is continued; but the
+degree in which the primitive cartilage is replaced by concentric or
+radiating lamellæ of bone varies greatly in the various genera, and
+according to the age of the individuals. In the Rays all the vertebræ
+are completely ossified, and the anterior ones confluent into one
+continuous mass.
+
+In the majority of Chondropterygians the extremity of the vertebral
+column shows a decidedly heterocercal condition (Fig. 31), and only a
+few, like _Squatina_ and some Rays, possess a diphycercal tail
+
+The advance in the development of the skeleton of the Chondropterygians
+beyond the primitive condition of the previous sub-classes, manifests
+itself further by the presence of neural and hæmal elements, which
+extend to the foremost part of the axial column, but of which the hæmal
+form a closed arch in the caudal region only, whilst on the trunk they
+appear merely as a lateral longitudinal ridge.
+
+  [Illustration: Fig. 32. Fig. 33. Fig. 34.
+
+  Fig. 32.--Lateral view. Fig. 33.--Longitudinal section. Fig.
+  34.--Transverse section of Caudal vertebra of Basking Shark
+  (Selache maxima). (After Hasse.) _a_, Centrum; _b_,
+  Neurapophysis; _c_, Intercrural cartilage; _d_,
+  Hæmapophysis; _e_, Spinal canal; _f_, Intervertebral
+  cavity; _g_, Central canal for persistent portion of
+  notochord; _h_, Hæmal canals for blood-vessels.]
+
+The neural and hæmal apophyses are either merely attached to the
+axis, as in Chondropterygians with persistent notochord, the Rays
+and some Sharks; or their basal portions penetrate like wedges into
+the substance of the centrum, so that, in a transverse section, in
+consequence of the difference in their texture, they appear in the
+form of an X.[6] The interspaces between the neurapophyses of the
+vertebræ are not filled by fibrous membrane, as in other fishes, but
+by separate cartilages, _laminæ_ or _cartilagines intercrurales_, to
+which frequently a series of terminal pieces is superadded, which
+must be regarded as the first appearance of the interneural spines
+of the Teleostei and many Ganoids. Similar terminal pieces are
+sometimes observed on the hæmal arches. _Ribs_ are either absent or but
+imperfectly represented (_Carcharias_).
+
+The substance of the _skull_ of the Chondropterygians is cartilage,
+interrupted especially on its upper surface by more or less extensive
+fibro-membranous fontanelles. Superficially it is covered by a more or
+less thick chagreen-like osseous deposit. The articulation with the
+vertebral column is effected by a pair of lateral condyles. In the
+Sharks, besides, a central conical excavation corresponds to that of
+the centrum of the foremost vertebral segment, whilst in the Rays this
+central excavation of the skull receives a condyle of the axis of the
+spinous column.
+
+The cranium itself is a continuous undivided cartilage, in which the
+limits of the orbit are well marked by an anterior and posterior
+protuberance. The ethmoidal region sends horizontal plates over
+the nasal sacs, the apertures of which retain their embryonic
+situation upon the under surface of the skull. In the majority of
+Chondropterygians these plates are conically produced, forming the base
+of the soft projecting snout; and in some forms, especially in the
+long-snouted Rays and the Saw-fishes (_Pristis_) this prolongation
+appears in the form of three or more tubiform rods.
+
+As separate cartilages there are appended to the skull a suspensorium,
+a palatine, mandible, hyoid, and rudimentary maxillary elements.
+
+The suspensorium is movably attached to the side of the skull. It
+generally consists of one piece only, but in some Rays of two. In the
+Rays it is articulated with the mandible only, their hyoid possessing
+a distinct point of attachment to the skull. In the Sharks the hyoid
+is suspended from the lower end of the suspensorium together with the
+mandible.
+
+What is generally called the upper jaw of a Shark is, as Cuvier has
+already stated, not the maxillary, but palatine. It consists of two
+simple lateral halves, each of which articulates with the corresponding
+half of the lower jaw, which is formed by the simple representative of
+Meckel’s cartilage.
+
+Some cartilages of various sizes are generally developed on each side
+of the palatine, and one on each side of the mandible. They are called
+_labial_ cartilages, and seem to represent maxillary elements.
+
+The _hyoid_ consists generally of a pair of long and strong lateral
+pieces, and a single mesial piece. From the former cartilaginous
+filaments (representing branchiostegals) pass directly outwards.
+Branchial arches, varying in number, and similar to the hyoid, succeed
+it. They are suspended from the side of the foremost part of the
+spinous column, and, like the hyoid, bear a number of filaments.
+
+The vertical fins are supported by interneural and interhæmal
+cartilages, each of which consists of two and more pieces, and to which
+the fin-rays are attached without articulation.
+
+The _scapular arch_ of the Sharks is formed by a single coracoid
+cartilage bent from the dorsal region downwards and forwards. In some
+genera (_Scyllium_, _Squatina_) a small separate scapular cartilage
+is attached to the dorsal extremities of the coracoid; but in none of
+the Elasmobranchs is the scapular arch suspended from the skull or
+vertebral column; it is merely sunk, and fixed in the substance of
+the muscles. Behind, at the point of its greatest curvature, three
+carpal cartilages are joined to the coracoid, which Gegenbaur has
+distinguished as _propterygium_, _mesopterygium_, and _metapterygium_,
+the former occupying the front, the latter the hind margin of the fin.
+Several more or less regular transverse series of styliform cartilages
+follow. They represent the phalanges, to which the horny filaments
+which are imbedded in the skin of the fin are attached.
+
+In the Rays, with the exception of _Torpedo_, the scapular arch is
+intimately connected with the confluent anterior portion of the
+vertebral column. The anterior and posterior carpal cartilages are
+followed by a series of similar pieces, which extend like an arch
+forwards to the rostral portion of the skull, and backwards to the
+pubic region. Extremely numerous phalangeal elements, longest in the
+middle, are supported by the carpals, and form the skeleton of the
+lateral expansion of the so-called _disk_ of the Ray’s body, which
+thus, in fact, is nothing but the enormously enlarged pectoral fin.
+
+The _pubic_ is represented by a single median transverse cartilage,
+with which a tarsal cartilage articulates. The latter supports the
+fin-rays. To the end of this cartilage is also attached, in the male
+Chondropterygians, a peculiar accessory generative organ or clasper.
+
+The _Holocephali_ differ from the other Chondropterygians in several
+important points of the structure of their skeleton, and approach
+unmistakably certain Ganoids. That their spinal column is persistently
+notochordal has been mentioned already. Their palatal apparatus, with
+the suspensorium, coalesces with the skull, the mandible articulating
+with a short apophysis of the cranial cartilage. The mandible is
+simple, without anterior symphysis. The spine with which the dorsal
+fin is armed articulates with a neural apophysis, and is not immovably
+attached to it, as in the Sharks. The pubic consists of two lateral
+halves, with a short, rounded, tarsal cartilage.
+
+The skeleton of the _Ganoid_ Fishes offers extreme variations with
+regard to the degree in which ossifications replace the primordial
+cartilage. Whilst some exhibit scarcely any advance beyond the
+Plagiostomes with persistent cartilage, others approach, as regards the
+development and specialisation of the several parts of their osseous
+framework, the Teleosteans so closely that their Ganoid nature can
+be demonstrated by, or inferred from, other considerations only. All
+Ganoids possess a separate gill-cover.[7]
+
+The diversity in the development of the Ganoid skeleton is well
+exemplified by the few representatives of the order in the existing
+Fish-fauna. Lowest in the scale (in this respect) are those with a
+persistent notochord, and an _autostylic_ skull, that is, a skull
+without separate suspensorium--the fishes constituting the suborder
+_Dipnoi_, of which the existing representatives are _Lepidosiren_,
+_Protopterus_, and _Ceratodus_, and the extinct (as far as demonstrated
+at present) _Dipterus_, _Chirodus_ (and _Phaneropleuron_?). In these
+fishes the notochord is persistent, passing uninterruptedly into the
+cartilaginous base of the skull. Only now and then a distinct vertical
+segmentation occurs in the caudal portion of the column, but it does
+not extend to the notochord itself, but indicates only the limits
+between the superadded apophyseal elements, each neural being confluent
+with the opposite hæmal. Some _Dipnoi_ are diphy-, others heterocercal.
+
+Neural and hæmal elements and ribs are well developed. In _Ceratodus_
+each neurapophysis consists of a basal cartilaginous portion, forming
+an arch over the myelon, and of a superadded second portion. The
+latter is separated from the former by a distinct line of demarcation,
+and its two branches are more styliform, cartilaginous at the ends
+and in the centre, but with an osseous sheath, and coalesced at the
+top, forming a gable over an elastic fibrous band which runs along
+and parallel to the longitudinal axis of the column (_Ligamentum
+longitudinale superius_). To the top of this gable is joined a single
+long cylindrical neural spine. From the eleventh apophyseal segment a
+distinct interneural spine, of the same structure as the neural, begins
+to be developed, and farther on a second interneural is superadded.
+Towards the extremity of the column these various pieces are gradually
+reduced in size and number, finally only a low cartilaginous band (the
+rudiments of the neurapophysis) remaining. The _hæmapophyses_ are in
+form, size, and structure, very similar to the neurapophyses; and all
+these long bones, including the ribs, have that in common, that they
+consist of a solid rod of cartilage enclosed in a bony sheath, which,
+after the disappearance or decomposition of the cartilage, appears as
+a hollow tube. Such bones are extremely common throughout the order of
+Ganoids, and their remains have led to the designation of a family as
+_Cœlacanthi_ (κοιλος, hollow; and ἀκανθος, spine).
+
+The primordial _cranium_ of the _Dipnoi_ is cartilaginous, but with
+more or less extensive ossifications in its occipital, basal, or
+lateral portions, and with large tegumentary bones, the arrangement
+of which varies in the different genera. There is no separate
+suspensorium for the lower jaw. A strong process descends from the
+cranial cartilage, and offers by means of a double condyle (Fig. 35
+_s_) attachment to corresponding articulary surfaces of the lower
+jaw. Maxillary and intermaxillary elements are not developed, but,
+perhaps, represented in _Ceratodus_ by some inconstant rudimentary
+labial cartilages situated behind the posterior nasal opening.
+Facial cartilages and an infraorbital ring are developed at least
+in _Ceratodus_. The presence of a pair of small teeth in front
+indicates the vomerine portion (_v_) which remains cartilage, whilst
+the posterior pair of teeth are implanted in a pterygo-palatine
+ossification (_l_), which sometimes is paired, sometimes continuous.
+The base of the skull is constantly covered by a large basal
+ossification (_o_).
+
+  [Illustration: Fig. 35.--Palatal view of Skull of Ceratodus.]
+
+The _hyoid_ is well developed, sometimes reduced to a pair of
+ceratohyals, sometimes with a basihyal and glossyhyal. The skeleton of
+the _branchial apparatus_ approaches the Teleosteous type, less so in
+_Lepidosiren_ than in _Ceratodus_, in which five branchial arches are
+developed, but with the lateral and mesial pieces reduced in number.
+
+A large operculum, and a smaller sub- or interoperculum are present.
+
+The _scapular_ arch consists of a single median transverse cartilage,
+and a pair of lateral cartilages which bear the articular condyle for
+the pectoral limb. The latter cartilages form the base of a large
+membrane-bone, and the whole arch is suspended from the skull by means
+of an osseous supraclavicle.
+
+The fore-limb of the _Dipnoi_ (Fig. 36) differs externally greatly
+from the pectoral fin of other Ganoid fishes. It is covered with
+small scales along the middle, from the root to its extremity, and
+surrounded by a rayed fringe similar to the vertical fin. A muscle
+split into numerous fascicles extends all the length of the fin, which
+is flexible in every part and in every direction. The cartilaginous
+framework supporting it is joined to the scapular arch by an oblong
+cartilage, followed by a broad basal cartilage (_a_), generally single,
+sometimes showing traces of a triple division. Along the middle of the
+fin runs a jointed axis (_b_), the joints gradually becoming smaller
+and thinner towards the extremity; each joint bears on each side a
+three, two, or one-jointed branch (_c, d_). This _axial_ arrangement of
+the pectoral skeleton, which evidently represents one of its first and
+lowest conditions, has been termed _Archipterygium_ by Gegenbaur. It is
+found in _Ceratodus_ and other genera, but in _Lepidosiren_ the jointed
+axis only has been preserved, with the addition of rudimentary rays in
+_Protopterus_.
+
+  [Illustration: Fig. 36.--Fore-limb of Ceratodus.]
+
+The _pubic_ consists of a single flattened subquadrangular cartilage,
+produced into a long single anterior process. Posteriorly it terminates
+on each side in a condyle, to which the basal cartilage of the ventral
+paddle is joined. The endoskeleton of the paddle is almost identical
+with that of the pectoral.
+
+The Ganoid fishes with persistent notochord, but with a _hyostylic_
+skull (that is, a skull with a separate suspensorium) consist of the
+suborder _Chondrostei_, of which the existing representatives are the
+Sturgeons (_Acipenser_, _Scaphirhynchus_, _Polyodon_), and the extinct
+the _Chondrosteidæ_, _Palæoniscidæ_, and (according to Traquair)
+_Platysomidæ_.
+
+Their spinal column does not differ essentially from that of the
+Dipnoi. Segmentation is represented only as far as the neural and
+hæmal elements are concerned. All are eminently heterocercal. Ribs are
+present in most, but replaced by ligaments in _Polyodon_.
+
+  [Illustration: Fig. 37.--Skull of Polyodon (after Traquair).
+
+    _n_, Nasal cavity; _sq_, squamosal; _mh_, hyomandibular;
+    _sy_, symplectic; _pa_, palato-pterygoid; _m_, Meckelian
+    cartilage; _mx_, maxillary; _d_, dentary; _h_, hyoid; _op_,
+    opercle; _br_, branchiostegal; _s.cl_, supra-clavicular;
+    _p.cl_, post-clavicular; _cl_, clavicle; _i.cl_,
+    infra-clavicular.]
+
+The primordial cranium of the Sturgeons consists of persistent
+cartilage without ossifications in its substance, but superficial bones
+are still more developed and specialised than in the Dipnoi; so it is,
+at least, in the true Sturgeons, but less so in _Polyodon_ (Fig. 37).
+The upper and lateral parts of the skull are covered by well-developed
+_membrane bones_, which, from this suborder, upwards in the series,
+will be found to exist throughout the remaining forms of fishes. They
+are bones, the origin of which is not in cartilage but in membranous
+connective tissue. The lower surface of the skull is covered by an
+extremely large basal bone, which extends from the vomerine region
+on to the anterior part of the spinal column. The nasal excavation
+in the skull is rather lateral than inferior. The ethmoidal region
+is generally much produced, forming the base of the long projecting
+snout. The suspensorium is movably attached to the side of the skull,
+and consists of two pieces, a hyomandibular and a symplectic, which
+now appears for the first time as a separate piece, and to which the
+hyoid is attached. The palato-maxillary apparatus is more complex
+than in the Sharks and Dipnoi; a palato-pterygoid consists of two
+mesially-connected rami in _Polyodon_, and of a complex cartilaginous
+disk in _Acipenser_, being articulated in both to the Meckelian
+cartilage. In addition, the Sturgeons possess one or two pairs of
+osseous rods, which, in _Polyodon_ at least, represent the maxillary,
+and therefore must be the representatives of the labial cartilages
+of the Sharks. The Meckelian cartilage is more or less covered by
+tegumentary bones.
+
+In the gill-cover, besides the operculum, a sub- and interoperculum may
+be distinguished in _Acipenser._
+
+The hyoid consists of three pieces, of which the posterior bears a
+broad branchiostegal in _Polyodon._
+
+In the scapulary arch the primordial cartilaginous elements scarcely
+differ from those of the _Dipnoi._ The membrane-bones are much
+expanded, and offer a continuous series suspended from the skull. Their
+division in the median ventral line is complete.
+
+  [Illustration: Fig. 38.--Fore-limb of Acipenser.]
+
+The pectoral is supported by a cartilaginous framework (Fig. 38)
+similar to that of _Ceratodus_, but much more shortened and reduced in
+its periphery, the branches being absent altogether on one side of the
+axis. This modification of the fin is analogous to the heterocercal
+condition of the end of the spinous column. To the inner corner of a
+basal cartilage (_a_) a short axis (_b_) is joined, which on its outer
+side bears a few branches (_d_) only, the remaining branches (_c_)
+being fixed to the basal cartilage. The dermal fin-rays are opposed to
+the extremities of the branches, as in the _Dipnoi_.
+
+The _pubic_ consists of a paired cartilage, to which tarsal pieces
+supporting the fin-rays are attached.
+
+The other living Ganoid fishes have the spinous column entirely or
+nearly entirely ossified, and have been comprised under the common name
+_Holostei_. However, they form three very distinct types; several
+attempts have been made to coordinate with them the fossil forms, but
+this task is beset with extreme difficulties, and its solution hitherto
+has not proved to be satisfactory.
+
+The _Polypteroidei_ have their spinous column formed by distinct
+osseous _amphicœlous_ vertebræ, that is, vertebræ with concave anterior
+and posterior surfaces. It is nearly diphycercal; a slight degree of
+heterocercy obtains, inasmuch as the last vertebra is succeeded by a
+very thin cartilaginous filament which penetrates between the halves
+of one of the middle rays of the terminal fin. The rays above this
+cartilaginous filament are articulated to interneurals, those below
+lack interhæmals, and are attached either to the hæmals or vertebral
+centres. The neural arches, though ossified, do not coalesce with
+the centrum, and form one canal only, for the myelon. There are
+no intermediate elements between the neural spines. Interneurals
+developed, but simple, articulating with the dermoneurals. The
+abdominal vertebræ have parapophyses developed with epipleural
+spines. Only the caudal vertebræ have hæmal spines, which, like the
+interhæmals, agree in every essential respect with the opposite
+neurals. _Ribs_ are inserted, not on the parapophyses, but on the
+centre, immediately below the parapophyses.
+
+The _skull_ of _Polypterus_ (Fig. 39) shows a great advance towards
+the Teleosteous type, the number of separable bones being greatly
+increased. They are arranged much in the same fashion as in Teleostei.
+But a great portion of the primordial cranium remains cartilaginous.
+The membrane-bones which cover the upper and lower surfaces of the
+brain-case are so much developed as to cause the underlying cartilage
+to disappear, so that a large vacuity or fontanelle exists in the
+substance of the upper as well as lower cartilaginous wall. Of
+ossifications belonging to the primordial skull must be noticed the
+single occipital with a mastoid on each side. They are separated by
+persistent cartilage from the sphenoids and postfrontals; the former,
+which are the largest ossification of the primordial cranium, enclose
+the anterior half of the brain cavity. Finally, the nasal portion
+contains a median ethmoid and a pair of præfrontal bones.
+
+  [Illustration: Fig. 39.--Skull of Polypterus. (After Traquair.)
+
+   Fig. I. Upper aspect of the Primordial Cranium, with the
+   membrane-bones removed. Fig. II. Lower aspect of the same. Fig.
+   III. Side view, with the membrane-bones. Fig. IV. Lower aspect
+   of the Skull, part of the bones being removed on one side. The
+   parts shaded with oblique lines are cartilage of the primordial
+   skull.
+
+   _An_, Angular; _ao_, ante-orbital; _Ar_,
+   articulary; _B_, basal; _D_, dentary; _E_,
+   ethmoid; _F_, frontal; _Ma_, mastoid; _Mp_,
+   metapterygoid; _Mx_, maxillary; _N_, nasal; _O_,
+   operculum; _Oc_, occipital; _Pa_, parietal; _Pl_,
+   palatine; _Pmx_, præmaxillary; _po_, post-orbital;
+   _Prf_, prefrontal; _Pt_, post-temporals; _Ptf_,
+   postfrontal; _Ptr_, pterygoid; _Q_, quadrate;
+   _S_, suspensorium; _So_, sub-operculum; _Sp_,
+   sphenoid; _Spl_, splenial; _St_, supratemporals;
+   _T_, tympanic lamina; _Tu_, turbinal; _v_, vomer;
+   _x x_, small ossicles; _x’ x’_, spiraculars.]
+
+
+Only a very small portion of the bones described are visible
+externally, nearly the whole of the primordial cranium being covered
+by the membrane-bones. Of these are seen on the upper surface a pair
+of parietals, frontals, “nasals,” and turbinals; on the lower surface
+a large cross-shaped basal, anteriorly bordered on each side by a
+pterygoid, parallel to a palatine which forms a suture with the double
+vomer. The suspensorium has in front a metapterygoid and quadrate bone,
+and an operculum and sub-operculum are attached to it behind.
+
+Præmaxillaries and maxillaries are now fully developed, but immovably
+attached to the skull. The lower jaw is ossified, and consists of an
+articulary, angular, dentary, and splenial. Of labial cartilages a
+rudiment at the angle of the mouth has remained persistent.
+
+The side of the skull, in front of the operculum, is covered by a large
+irregularly-shaped bone (_T_) (corresponding to the “tympanic lamina”
+of _Ceratodus_, Fig. 35, _q_), held by some to be the præoperculum;
+along its upper circumference lies a series of small ossicles, of which
+two may be distinguished as spiraculars, as they form a valve for the
+protection of the spiracular orifice of these fishes. An infraorbital
+ring is represented by a præ- and post-orbital only.
+
+Each _hyoid_ consists of three pieces, none of which bear
+branchiostegals, the single median piece being osseous in front and
+cartilaginous behind. Four branchial arches are developed, the foremost
+consisting of three, the second and third of two, and the last of a
+single piece. There is no lower pharyngeal. Between the rami of the
+lower jaw the throat is protected by a pair of large osseous laminæ
+(_gular plates_), which have been considered to represent the urohyal
+of osseous fishes.
+
+The scapulary arch is almost entirely formed by the well-developed
+membrane-bones, which in the ventral line are suturally united.
+The pectoral fin is supported by three bones, pro-, meso-, and
+metapterygium, of which the dilated middle one alone bears rays, and is
+excluded from the articulation with the shoulder-girdle.
+
+The pubic consists of paired bone, to which tarsal bones supporting the
+fin-rays are attached.
+
+In the _Lepidosteoidei_ the vertebræ are completely ossified, and
+_opisthocœlous_, having a convexity in front and a concavity behind,
+as in some Amphibians. Though the end of the body externally appears
+nearly diphycercal, the termination of the vertebral column is,
+in fact, distinctly heterocercal (Fig. 40). Its extremity remains
+cartilaginous, is turned upwards, and lies immediately below the scutes
+which cover the upper margin of the caudal fin. It is preceded by a
+few rudimentary vertebræ which gradually pass into the fully developed
+normal vertebræ. The caudal fin is suspended from hæmapophyses only,
+and does not extend to the neural side of the vertebral column. The
+neural arches coalesce with the centrum; interneurals simple. The
+abdominal vertebræ have parapophyses, to which the ribs are attached.
+Only the caudal vertebræ have hæmal spines.
+
+  [Illustration: Fig. 40.--Heterocercal Tail of Lepidosteus.
+
+    _n_, Vertebral column; _h_, hæmal spines; _dn_, fulcra; _dh_,
+    lower fulcra.]
+
+In the skull of _Lepidosteus_ the cartilage of the endocranium is
+still more replaced by ossifications than in _Polypterus_; those
+ossifications, moreover, being represented by a greater number of
+discrete bones; especially the membrane-bones are greatly multiplied:
+the occipital, for instance, consists of three pieces; the vomer is
+double as in _Polypterus_; the maxillary consists of a series of
+pieces firmly united by suture. The symplectic reaches the lower jaw,
+so that the articulary is provided with a double joint, viz. for the
+symplectic and quadrate; the component parts of the lower jaw are as
+numerous as in reptiles, a dentary, splenial, articulary, angular,
+supra-angular, and coronary being distinct. The sides of the head
+are covered with numerous bones, and a præoperculum is developed in
+front of the gill-cover which, again, consists of an operculum and
+sub-operculum.
+
+Each hyoid consists of three pieces, of which the middle is the
+longest, the upper bearing the largest of the three branchiostegals
+which _Lepidosteus_ possesses; a long and large glossohyal is
+intercalated between the lower ends of the hyoids. There are five
+branchial arches, the hindmost of which is modified into a lower
+pharyngeal; upper pharyngeals are likewise present as in the majority
+of Teleosteous fishes. No gular plate.
+
+Of the scapulary arch the two halves are separated by a suture in the
+median line; the membrane-bones are well developed, only a remnant of
+the primordial cartilage remaining; the supraclavicle is very similar
+to that of Teleosteous fishes, less so the post-temporal. The base to
+which the limb is attached is a single osseous plate, supporting on its
+posterior margin semi-ossified rods in small number, which bear the
+pectoral rays.
+
+The pubic consists of paired bone, the anterior ends of which overlap
+each other, the extremity of the right pubis being dorsad to that of
+the left. The elements representing a tarsus are quite rudimentary and
+reduced in number (two or three).
+
+The vertebral column of the _Amioidei_ shows unmistakable characters
+of the Palæichthyic type. The arrangement of its component parts is
+extremely simple. The centra of the amphicœlous vertebræ are well
+ossified, but the neural and hæmal arches do not coalesce with the
+centra, from which they are separated by a thin layer of cartilage.
+Singularly, not every vertebra has apophyses: in the caudal portion of
+_Amia_ the vertebræ are alternately provided with them and lack them.
+The heterocercal condition of the spinous column is well marked: as in
+the other Holostei the hindmost vertebræ are turned upwards, become
+smaller and smaller in size, and lose their neural arches, the hæmals
+remaining developed to the end. Finally, the column terminates in a
+thin cartilaginous band, which is received between the lateral halves
+of the fifth or sixth upper caudal ray. Interneurals and interhæmals
+simple. Only the abdominal vertebræ have parapophyses, with which the
+ribs are articulated.
+
+The configuration of the skull, and the development and arrangement
+of its component parts, approaches so much the Teleosteous type that,
+perhaps, there are greater differences in skulls of truly Teleosteous
+fishes than between the skulls of _Amia_ and many _Physostomi_.
+Externally the cranium is entirely ossified; and the remains of the
+cartilaginous primordial cranium (which, however, has no vacuity in its
+roof) can only be seen in a section, and are of much less extent than
+in many Physostomous fishes. The immovable intermaxillary, the double
+vomer, the plurality of ossifications representing the articulary,
+the double articulary cavity of the mandible for junction with the
+quadrate and symplectic bones, remind us still of similar conditions
+in the skull of _Lepidosteus_, but the mobility and formation of the
+maxillary, the arrangement of the gill-covers, the development of the
+opercles, the suspensorium, the palate, the insertion of a number of
+branchiostegals on the long middle hyoid piece, the composition of the
+branchial framework (with upper and lower pharyngeals), are as in the
+Teleosteous type. A gular plate replaces the urohyal.
+
+The scapular arch is composed entirely of the membrane-bones found in
+the _Teleostei_, and the two sides are loosely united by ligament.
+The base to which the limb is attached is cartilaginous; short
+semi-ossified rods are arranged along its hinder margin and bear the
+pectoral rays.
+
+The skeleton of the hind-limb agrees entirely with that of
+_Lepidosteus_.
+
+   [T. W. Bridge, The Cranial Osteology of _Amia calva_; in
+   Journ. Anat. and Physiol. vol. xi.]
+
+In the _Teleosteous_ fishes the spinous column consists of completely
+ossified amphicœlous vertebræ; its termination is _homocercal_--that
+is, the caudal fin appears to be more or less symmetrical, the last
+vertebra occupying a central position in the base of the fin, and being
+coalesced with a flat osseous lamella, the _hypural_ (Fig. 23, 70), on
+the hind margin of which the fin-rays are fixed. The hypural is but a
+union of modified hæmapophyses which are directed backwards, and the
+actual termination of the notochord is bent upwards, and lies along the
+upper edge of the hypural, hidden below the last rudimentary neural
+elements. In some Teleosteans, as the _Salmonidæ_, the last vertebræ
+are conspicuously bent upwards: in fact, strictly speaking, this
+homocercal condition is but one of the various degrees of heterocercy,
+different from that of many Ganoids in this respect only, that the
+caudal fin itself has assumed a higher degree of symmetry.
+
+The neural and hæmal arches generally coalesce with the centrum, but
+there are many exceptions, inasmuch as some portion of the arches of a
+species, or all of them, show the original division.
+
+The vertebræ are generally united with one another by zygapophyses, and
+frequently similar additional articulations exist at the lower parts
+of the centra. Parapophyses and ribs are very general, but the latter
+are inserted on the centra and the base of the processes, and never on
+their extremities. The point of insertion of the rib, more especially
+on the anterior vertebræ, may be still higher--viz. at the base of the
+neural arch, as in _Cotylis_ and allied genera, and even on the top of
+the neurapophysis, as in _Batrachus_.
+
+There is a great amount of variation as regards the degree in which
+the primordial cranium persists; it is always more or less replaced by
+bone; frequently it disappears entirely, but in some fishes, like the
+_Salmonidæ_ or _Esocidæ_, the cartilage persists to the same or even
+to a greater extent than in the Ganoidei holostei. Added to the bones
+preformed in cartilage are a great number of _membrane-bones_. The
+different kinds of these membrane-bones occur with greater or less
+constancy throughout this sub-class; they often coalesce with, and are
+no more separable from, the neighbouring or underlying cartilage-bones.
+All these bones have been topographically enumerated in Chapter IV.
+
+Many attempts have been made to classify the bones of the Teleosteous
+skull, according to their supposed relation to each other, or with
+the view to demonstrate the unity of plan on which the skull has been
+built; but in all either the one or the other of the following two
+principles has been followed:--
+
+A. The “vertebral doctrine” starts from the undeniable fact that the
+skull is originally composed of several segments, each of which is
+merely the modification of a vertebra. The component parts of such a
+cranial segment are considered to be homologous to those of a vertebra.
+Three, four, or five cranial vertebræ have been distinguished, all
+the various bones of the fully-developed and ossified skull being
+referred, without distinction as to their origin, to one or the other
+of those vertebral segments. The idea of the typical unity of the
+osseous framework of Vertebrates has been worked out with the greatest
+originality and knowledge of detail, by _Owen_, who demonstrates that
+the fish-skull is composed of _four_ vertebræ.
+
+The bones of the fish-skull are, according to him, primarily
+divisible into those of the _neuroskeleton_, _splanchnoskeleton_, and
+_dermoskeleton_.
+
+The bones of the _neuro_- or proper _endoskeleton_ are arranged in
+a series of four horizontally succeeding segments: the occipital,
+parietal, frontal, and nasal vertebræ; each segment consisting of an
+upper (neural) and a lower (hæmal) arch, with a common centre, and with
+diverging appendages.
+
+The _neural_ arches of the four vertebræ, in their succession from the
+occiput towards the snout, are:--
+
+1. _Epencephalic arch_, composed of the occipitals.
+
+2. _Mesencephalic arch_, composed of basisphenoid, alisphenoid,
+parietal, and mastoid.
+
+3. _Prosencephalic arch_, composed of presphenoid, orbito-sphenoid,
+frontal, and postfrontal.
+
+4. _Rhinencephalic arch_, composed of vomer, prefrontal, and nasal.
+
+The _hæmal_ arches in the same order of succession are:--
+
+1. _Scapular_ or _scapulo-coracoid_ arch, composed of suprascapula,
+scapula, and coracoid; its appendage consists of the ulna, radius and
+carpal.
+
+2. _Hyoid_ or _stylo-hyoid_ arch, composed of stylohyal, epihyal,
+ceratohyal, basihyal, glossohyal, and urohyal; its appendage is the
+branchiostegals.
+
+3. _Mandibular_ or _tympano-mandibular_ arch, composed of epi-, meso-,
+pre-, and hypo-tympanic, and the bones of the lower jaw; its appendage
+consists of the præoperculum and the other opercles.
+
+4. _Maxillary_ or _palato-maxillary_ arch, composed of palatine,
+maxillary, and premaxillary; its appendage consists of the pterygoid
+and entopterygoid.
+
+Parts of the _splanchnoskeleton_ are held to be the ear-capsule
+or petrosal and the otolite, the eye-capsule or sclerotic, the
+nose-capsule or “ethmoid” and turbinal; the branchial arches.
+
+The bones of the _dermoskeleton_ are the supratemporals, supraorbitals,
+suborbitals, and labials.
+
+B. In the second method of classifying the bones of the skull
+prominence is given to the facts of their different origin as
+ascertained by a study of their development. The parts developed from
+the primordial skull, or the cartilaginous case protecting the nervous
+centre are distinguished from those which enclose and support the
+commencement of the alimentary canal and the respiratory apparatus, and
+which, consisting of several arches, are comprised under the common
+name of _visceral skeleton of the skull_. Further, a distinction is
+made between the bones preformed in cartilage and those originating in
+tegumentary or membranous tissue. It is admitted that the primordial
+cranium is a coalition of several segments, the number of which is
+determined by that of the visceral arches, these representing the hæmal
+arches of the vertebral column; but the membrane-bones are excluded
+from a consideration of the vertebral division of the primordial skull,
+as elements originally independent of it, although these additions have
+entered into special relations to the cartilage-bones.
+
+With these views the bones of the Teleosteous skull are classified
+thus:--
+
+1. _Cartilage-bones of the primordial skull_.--The _basi-occipital_
+(5 in Figs. 23–26) has retained the form of a vertebral centrum; it
+is generally concave behind, the concavity containing remains of the
+notochord; rarely a rounded articulary head of the first vertebra fits
+into it, as in _Symbranchus_, and still more rarely it is provided
+with such an articulary head (_Fistularia_); frequently it shows two
+excavations on its inner surface for the reception of the _saccus
+vestibuli_. The _exoccipitals_ (10) are situated on the side of the
+basi-occipital, and contribute the greater portion of the periphery of
+the foramen magnum; frequently they articulate with the first vertebra,
+or meet in the upper median line, so as to exclude the supraoccipital
+from the foramen magnum. The _supraoccipital_ (8) is intercalated
+between the exoccipitals, and forms a most prominent part by the median
+crest, which sometimes extends far forwards on the upper side of the
+skull, and offers attachment to the dorsal portion of the large lateral
+muscle of the trunk. When the interior portions of this bone remain
+cartilaginous, some part of the semicircular canals may be lodged in it.
+
+The region of the skull which succeeds the bones described encloses at
+least the greater portion of the labyrinth, and its component parts
+have been named with reference to it by some anatomists.[8] The
+_alisphenoids_ (11) (_Prooticum_) form sutures posteriorly with the
+basi- and exoccipitals, and meet each other in the median line at the
+bottom of the cerebral cavity; they contribute to the formation of a
+hollow in which the hypophysis cerebri and the saccus vasculosus are
+received; in conjunction with the exoccipital it forms another hollow
+for the reception of the vestibulum; generally it is perforated by the
+Trigeminal and Facial nerves. The _paroccipitals_ (9) (_Epioticum_)
+lodge a portion of the posterior vertical semicircular canal, and form
+a projection of the skull on each side of the occipital crest, to which
+a terminal branch of the scapular arch is attached. The _Mastoid_ (12
++ 13) (_Opisthoticum_) occupies the postero-external projection of
+the head; it encloses a part of the external semicircular canal; is
+generally coalesced with a membrane-bone, the superficial _squamosal_,
+which emits a process for the suspension of the scapular arch, and is
+frequently, as in the Perch, divided into two separate bones.
+
+The anterior portion of the skull varies greatly as regards form, which
+is chiefly dependent on the extent of the cerebral cavity; if the
+latter is advanced far forwards, the lateral walls of the primordial
+cranium are protected by more developed ossifications than if the
+cerebral cavity is shortened by the presence of a wide and deep orbit.
+In the latter case parts which normally form the side of the skull are
+situated in front of the brain-case, between it and the orbit, and
+generally reduced in extent, often replaced by membranes; especially
+the interorbital septum may be reduced to membrane. The most constant
+ossifications of this part of the skull are the _orbitosphenoids_
+(14), which join the upper anterior margin of the alisphenoids. They
+vary much with regard to their development--they are small in Gadoids;
+larger in the Perch, Pike, Salmonoids, Macrodon, and the Clupeoids;
+and very large in Cyprinoids and Siluroids, in which they contribute
+to the formation of the side of the brain-case. The single Y-shaped
+_Sphenoideum anterius_ (15) is as frequently absent as present; it
+forms the anterior margin of the fossa for the hypophysis. Finally, the
+_postfrontal_ (4) belongs also to this group of cartilage-bones.
+
+The centre of the foremost part of the skull is occupied by the
+_ethmoid_ (3), which shows great variations as regards its extent
+and the degree of ossification; it may extend backwards into the
+interorbital septum, and reach the orbitosphenoids, or may be confined
+to the extremity of the skull; it may remain entirely cartilaginous,
+or ossify into a lamina which separates the two orbits and encloses
+an anterior prolongation of the brain-case, along which the olfactory
+nerves pass: modifications occurring again in higher vertebrates. A
+paired ossification attached to the fore-part of the ethmoid is the
+_pre-frontals_ (2), which form the base of the nasal fossa.
+
+2. _Membrane-bones attached to the primordial skull_.--To this group
+belong the _parietals_ (7) and _frontals_ (1). The _squamosal_ (12) has
+been mentioned above in connection with the mastoid. The _supraorbital_
+is always small, and frequently absent. The lower surface of the skull
+is protected by the _basisphenoid_ (parasphenoid) (6) and the _vomer_
+(16), both of which, especially the latter, may be armed with teeth.[9]
+
+3. _Cartilage bones of the alimentary portion of the visceral skeleton
+of the skull_.--The suspensorium consists of three cartilage-bones,
+and affords a base for the opercular apparatus as well as a point of
+attachment to the hyoid, whilst in front it is connected with the
+palato-pterygo-palatine arch. They are the _hyomandibular_ (23),
+_symplectic_ (31), and _quadrate_ (26), connected by means of the
+_metapterygoid_ (27) with the _ecto-_ (24) and _ento-pterygoid_ (25),
+the foremost bone of the arch being the _palatine_ (22). All these
+bones have been sufficiently described above (p. 55), and it remains
+only to be mentioned that the bones of the palatine arch are but rarely
+absent, as for instance in _Murænophis_; and that the symplectic
+does not extend to the articulary of the mandible, as in _Amia_
+and _Lepidosteus_, though its suspensory relation to the Meckelian
+cartilage is still indicated by a ligament which connects the two
+pieces. Of the mandibulary bones the _articulary_ (35) is distinctly
+part of Meckel’s cartilage. Frequently another portion of cartilage
+below the articulary remains persistent, or is replaced by a separate
+membrane-bone, the angular.
+
+4. _Membrane-bones of the alimentary portion of the visceral skeleton
+of the skull_.--The suspensorium has one tegumentary bone attached
+to it, viz. the _præoperculum_ (30); it is but rarely absent, for
+instance in _Murænophis_. The _premaxillary_ (17) and _maxillary_ (18)
+of the Teleostei appear to be also membrane-bones, although they are
+clearly analogous to the upper labial cartilages of the Sharks. The
+premaxillaries sometimes coalesce into a single piece (as in _Diodon_,
+_Mormyrus_), or they are firmly united with the maxillaries (as in all
+_Gymnodonts_, _Serrasalmo_, etc.) The relative position and connection
+of these two bones differs much, and is a valuable character in the
+discrimination of the various families. In some, the front margin of
+the jaw is formed by the premaxillary only, the two bones having a
+parallel position, as it has been described in the Perch (p. 53); in
+others, the premaxillary is shortened, allowing the maxillary to enter,
+and to complete, the margin of the upper jaw; and finally, in many no
+part of the maxillary is situated behind the premaxillary, but the
+entire bone is attached to the end of the premaxillary, forming its
+continuation. In the last case the maxillary may be quite abortive.
+The mobility of the upper jaw is greatest in those fishes in which the
+premaxillary alone forms its margin. The form of the premaxillary is
+subject to great variation: the beak of _Belone_, _Xiphias_ is formed
+by the prolonged and coalesced premaxillaries. The maxillary consists
+sometimes of one piece, sometimes of two or three. The principal
+membrane-bone of the mandible is the _dentary_ (34), to which is added
+the _angular_ (36) and rarely a smaller one, the _splenial_ or os
+_operculare_, which is situated at the inside of the articulary.
+
+5. _Cartilage-bones of the respiratory portion of the visceral skeleton
+of the skull._--With few exceptions all the ossifications of the hyoid
+and branchial arches, as described above (p. 58), belong to this group.
+
+6. _Membrane-bones of the respiratory portion of the visceral skeleton
+of the skull._--They are the following: the opercular pieces, viz.
+_operculum_ (28), _sub-operculum_ (32), and _interoperculum_ (33). The
+last of these is the least constant; it may be entirely absent, and
+represented by a ligament extending from the mandible to the hyoid.
+The _urohyal_ (42) which separates the musculi sternohyoidei, and
+serves for an increased surface of their insertion; and finally the
+_branchiostegals_ (43), which vary greatly in number, but are always
+fixed to the cerato- and epi-hyals.
+
+7. _Dermal bones of the skull._--To this category are referred some
+bones which are ossifications of, and belong to, the cutis. They are
+the _turbinals_ (20), the _suborbitals_ (19), and the _supratemporals_.
+They vary much with regard to the degree in which they are developed,
+and are rarely entirely absent. Nearly always they are wholly or partly
+transformed into tubes or hollows, in which the muciferous canals with
+their numerous nerves are lodged. Those in the temporal and scapulary
+regions are not always developed; on the other hand, the series of
+those ossicles may be continued on to the trunk, accompanying the
+lateral line. In many fishes those of the infraorbital ring are much
+dilated, protecting the entire space between the orbit and the rim of
+the præoperculum; in others, especially those which have the angle of
+the præoperculum armed with a powerful spine, the infraorbital ring
+emits a process towards the spine, which thus serves as a stay or
+support of this weapon (_Scorpænidæ_, _Cottidæ_).
+
+The _pectoral_ arch of the Teleosteous fishes exhibits but a remnant of
+a primordial cartilage, which is replaced by two ossifications,[10] the
+_coracoid_ (51) and _scapula_ (52); they offer posteriorly attachment
+to two series of short rods, of which the proximal are nearly always
+ossified, whilst the distal frequently remain small cartilaginous
+nodules hidden in the base of the pectoral rays. The bones, by
+which this portion is connected with the skull, are membrane-bones,
+viz. the _clavicle_ (49), with the _postclavicle_ (49 + 50), the
+_supraclavicle_ (47), and _post-temporal_ (46). The order of their
+arrangement in the Perch has been described above (p. 59). However,
+many Teleosteous fish lack pectoral fins, and in them the pectoral arch
+is frequently more or less reduced or rudimentary, as in many species
+of _Murænidæ_. In others the membrane-bones are exceedingly strong,
+contributing to the outer protective armour of the fish, and then the
+clavicles are generally suturally connected in the median line. The
+postclavicula and the supraclavicula may be absent. Only exceptionally
+the shoulder-girdle is not suspended from the skull, but from the
+anterior portion of the spinous column (_Symbranchidæ_, _Murænidæ_,
+_Notacanthidæ_). The number of basal elements of each of the two series
+never exceeds five, but may be less; and the distal series is absent in
+Siluroids.
+
+The _pubic_ bones of the Teleosteous fishes undergo many modifications
+of form in the various families, but they are essentially of the same
+simple type as in the Perch.
+
+
+
+
+                              CHAPTER V.
+
+                               MYOLOGY.
+
+
+In the lowest vertebrate, _Branchiostoma_, the whole of the
+_muscular_ mass is arranged in a longitudinal band running along
+each side of the body; it is vertically divided into a number of flakes
+or segments (_myocommas_) by aponeurotic septa, which serve as the
+surfaces of insertion to the muscular fibres. But this muscular band
+has no connection with the notochord except in its foremost portion,
+where some relation has been formed to the visceral skeleton. A very
+thin muscular layer covers the abdomen.
+
+Also in the _Cyclostomes_ the greatest portion of the muscular
+system is without direct relation to the skeleton, and, again, it is
+only on the skull and visceral skeleton where distinct muscles have
+been differentiated for special functions.
+
+To the development of the skeleton in the more highly organised fishes
+corresponds a similar development of the muscles; and the maxillary
+and branchial apparatus, the pectoral and ventral fins, the vertical
+fins, and especially the caudal, possess a separate system of muscles.
+But the most noteworthy is the muscle covering the sides of the trunk
+and tail (already noticed in _Branchiostoma_), which Cuvier described
+as the “great lateral muscle,” and which, in the higher fishes, is a
+compound of many smaller segments, corresponding in number with the
+vertebræ. Each lateral muscle is divided by a median longitudinal
+groove into a dorsal and ventral half; the depression in its middle
+is filled by an embryonal muscular substance which contains a large
+quantity of fat and blood-vessels, and therefore differs from ordinary
+muscle by its softer consistency, and by its colour which is reddish
+or grayish. Superficially the lateral muscle appears crossed by a
+number of white parallel tendinous zig-zag stripes, forming generally
+three angles, of which the upper and lower point backwards, the middle
+one forwards. These are the outer edges of the aponeurotic septa
+between the myocommas. Each septum is attached to the middle and the
+apophyses of a vertebra, and, in the abdominal region, to its rib;
+frequently the septa receive additional support by the existence of
+epipleural spines. The fibres of each myocomma run straight and nearly
+horizontally from one septum to the next; they are grouped so as to
+form semiconical masses, of which the upper and lower have their apices
+turned backwards, whilst the middle cone, formed by the contiguous
+parts of the preceding, has its apex directed forward; this fits into
+the interspace between the antecedent upper and lower cones, the apices
+of which reciprocally enter the depressions in the succeeding segment,
+whereby all the segments are firmly locked together (_Owen_).
+
+In connection with the muscles reference has to be made to the
+_Electric organs_ with which certain fishes are provided, as it
+is more than probable, not only from the examination of peculiar
+muscular organs occurring in the Rays, _Mormyrus_, and _Gymnarchus_
+(the function of which is still conjectural), but especially from the
+researches into the development of the electric organ of _Torpedo_,
+that the electric organs have been developed out of muscular substance.
+The fishes possessing fully developed electric organs, with the power
+of accumulating electric force and communicating it in the form of
+shocks to other animals, are the electric Rays (_Torpedinidæ_), the
+electric Sheath-fish of tropical Africa (_Malapterurus_), and the
+electric Eel of tropical America (_Gymnotus_). The structure and
+arrangement of the electric organ is very different in these fishes,
+and will be subsequently described in the special account of the
+several species.
+
+The phenomena attending the exercise of this extraordinary faculty
+also closely resemble muscular action. The time and strength of the
+discharge are entirely under the control of the fish. The power is
+exhausted after some time, and it needs repose and nourishment to
+restore it. If the electric nerves are cut and divided from the brain
+the cerebral action is interrupted, and no irritant to the body has any
+effect to excite electric discharge; but if their ends be irritated
+the discharge takes place, just as a muscle is excited to contraction
+under similar circumstances. And, singularly enough, the application
+of strychnine causes simultaneously a tetanic state of the muscles and
+a rapid succession of involuntary electric discharges. The strength of
+the discharges depends entirely on the size, health, and energy of the
+fish: an observation entirely agreeing with that made on the efficacy
+of snake-poison. Like this latter, the property of the electric force
+serves two ends in the economy of the animals which are endowed with
+it; it is essential and necessary to them for overpowering, stunning,
+or killing the creatures on which they feed, whilst incidentally they
+use it as the means of defending themselves from their enemies.
+
+
+
+
+                              CHAPTER VI.
+
+                              NEUROLOGY.
+
+
+The most simple condition of the nervous central organ known in
+Vertebrates is found in _Branchiostoma_. In this fish the spinal
+chord tapers at both ends, an anterior cerebral swelling, or anything
+approaching a brain, being absent. It is band-like along its middle
+third, and groups of darker cells mark the origins of the fifty or
+sixty pairs of nerves which accompany the intermuscular septa, and
+divide into a dorsal and ventral branch, as in other fishes. The two
+anterior pairs pass to the membranous parts above the mouth, and supply
+with nerve filaments a ciliated depression near the extremity of the
+fish, which is considered to be an olfactory organ, and two pigment
+spots, the rudiments of eyes. An auditory organ is absent.
+
+The _spinal chord_ of the _Cyclostomes_ is flattened in its
+whole extent, band-like, and elastic; also in _Chimæra_ it is
+elastic, but flattened in its posterior portion only. In all other
+fishes it is cylindrical, non-ductile, and generally extending along
+the whole length of the spinal canal. The Plectognaths offer a singular
+exception in this respect that the spinal chord is much shortened, the
+posterior portion of the canal being occupied by a long cauda equina;
+this shortening of the spinal chord has become extreme in the Sun-fish
+(_Orthagoriscus_), in which it has shrunk into a short and conical
+appendage of the brain. Also in the Devil-fish (_Lophius_) a long
+cauda equina partly conceals the chord which terminates on the level of
+about the twelfth vertebra.
+
+The _brain_ of fishes is relatively small; in the Burbot
+(_Lota_) it has been estimated to be 1/720th part of the weight of
+the entire fish, in the Pike the 1/1305th part, and in the large Sharks
+it is relatively still smaller. It never fills the entire cavity of
+the cranium; between the dura mater which adheres to the inner surface
+of the cranial cavity, and the arachnoidea which envelops the brain, a
+more or less considerable space remains, which is filled with a soft
+gelatinous mass generally containing a large quantity of fat. It has
+been observed that this space is much less in young specimens than in
+adult, which proves that the brain of fishes does not grow in the same
+proportion as the rest of the body; and, indeed, its size is nearly the
+same in individuals of which one is double the bulk of the other.
+
+  [Illustration: Fig. 41.--Brain of Perch.
+
+  I. Upper aspect. II. Lower aspect.
+
+    _a_, cerebellum; _b_, optic lobes; _c_, hemispheres; _e_,
+    lobi inferiores; _f_, hypophysis; _g_, lobi posteriores; _i_,
+    Olfactory lobes; _n_, _N._ opticus; _o_, _N._ olfactorius;
+    _p_, _N._ oculo-motorius; _q_, _N._ trochlearis; _r_, _N._
+    trigeminus; _s_, _N._ acusticus; _t_, _N._ vagus; _u_, _N._
+    abducens; _v_, Fourth ventricle.]
+
+The brain of _Osseous fishes_ (Fig. 41) viewed from above shows three
+protuberances, respectively termed _prosencephalon_, _mesencephalon_,
+and _metencephalon_, the two anterior of which are paired, the hindmost
+being single. The foremost pair are the _hemispheres_, which are
+solid in their interior, and provided with two swellings in front,
+the _olfactory lobes_. The second pair are the _optic lobes_, which
+generally are larger than the hemispheres, and succeeded by the third
+single portion, _the cerebellum_. In the fresh state the hemispheres
+are of a grayish colour, and often show some shallow depressions on
+their surface; a narrow commissure of white colour connects them
+with each other. The optic lobes possess a cavity (_ventriculus
+lobioptici_), at the bottom of which some protuberances of variable
+development represent the corpora quadrigemina of higher animals. On
+the lower surface of the base of the optic lobes, behind the _crura
+cerebri_, two swellings are observed, the _lobi inferiores_, which
+slightly diverge in front for the passage of the _infundibulum_, from
+which a generally large _hypophysis_ or _pituitary gland_ is suspended.
+The relative size of the cerebellum varies greatly in the different
+osseous fishes: in the Tunny and Silurus it is so large as nearly to
+cover the optic lobes; sometimes distinct transverse grooves and a
+median longitudinal groove are visible. The cerebellum possesses in
+its interior a cavity which communicates with the anterior part of
+the fourth ventricle. The _medulla oblongata_ is broader than the
+spinal chord, and contains the _fourth ventricle_, which forms the
+continuation of the central canal of the spinal chord. In most fishes
+a perfect roof is formed over the fourth ventricle by two longitudinal
+pads, which meet each other in the median line (_lobi posteriores_),
+and but rarely it remains open along its upper surface.
+
+The brain of _Ganoid fishes_ shows great similarity to that of the
+Teleostei; however, there is considerable diversity of the arrangement
+of its various portions in the different types. In the Sturgeons and
+_Polypterus_ (Fig. 42) the hemispheres are more or less remote from
+the mesencephalon, so that in an upper view the crura cerebri, with
+the intermediate entrance into the third ventricle (_fissura cerebri
+magna_), may be seen. A vascular membranous sac, containing lymphatic
+fluid (_epiphysis_), takes its origin from the third ventricle, its
+base being expanded over the anterior interspace of the optic lobes,
+and the apex being fixed to the cartilaginous roof of the cranium.
+This structure is not peculiar to the Ganoids, but found in various
+stages of development in Teleosteans, marking, when present, the
+boundary between prosencephalon and mesencephalon. The lobi optici
+are essentially as in Teleosteans. The cerebellum penetrates into
+the ventriculus lobi optici, and extends thence into the open sinus
+rhomboidalis. At its upper surface it is crossed by a commissure formed
+by the _corpora restiformia_ of the medulla.
+
+  [Illustration: Fig. 42.--Brain of Polypterus. (After Müller.)
+
+  I., Upper; II., Lateral; III., Lower aspect.
+
+    _a_, Medulla; _b_, corpora restiformia; _c_, cerebellum;
+    _d_, lobi optici; _e_, hypophysis; _f_, fissura cerebri
+    magna; _g_, nervus opticus; _g_’, chiasma; _h_, hemispheres;
+    _i_, lobus olfactorius; _k_, sinus rhomboidalis (fourth
+    ventricle).]
+
+As regards external configuration, the brain of _Lepidosteus_
+and _Amia_ approach still more the Teleosteous type. The
+prosencephalon, mesencephalon, and metencephalon are contiguous, and
+the cerebellum lacks the prominent transverse commissure at its upper
+surface. The sinus rhomboidalis is open.
+
+The brain of the _Dipnoi_ shows characters reminding us of that of
+the Ganoids as well as the Chondropterygians, _Ceratodus_ agreeing
+with _Protopterus_ in this respect, as in most other points of
+its organisation. The hemispheres form the largest part of the brain;
+they are coalescent, as in Sharks, but possess two lateral ventricles,
+the separation being externally indicated by a shallow median groove
+on the upper surface. The olfactory lobes take their origin from
+the upper anterior end of the hemispheres. Epiphysis and hypophysis
+well developed. The lobi optici are very small, and remote from the
+prosencephalon, their division into the lateral halves being indicated
+by a median groove only. The cerebellum is very small, overlying the
+front part of the sinus rhomboidalis.
+
+  [Illustration: Fig. 43.--Brain of Carcharias. (After Owen.)
+
+    _ac_, Nerv. acusticus; _b_, corpus restiforme; _c_,
+    cerebellum; _d_, lobus opticus; _e_, hypophysis; _g_, nervus
+    opticus; _h_, hemisphere; _i_, lobus olfactorius; _i’_,
+    olfactory pedicle; _k_, nerv. olfactorius; _l_, epiphysis;
+    _m_, nerv. oculo-motorius; _tr_, nerv. trigeminus; _v_, nerv.
+    vagus.]
+
+The brain of _Chondropterygians_ (Fig. 43) is more developed than
+that of all other fishes, and distinguished by well-marked characters.
+These are, first, the prolongation of the olfactory lobes into more or
+less long pedicles, which dilate into great ganglionic masses, where
+they come into contact with the olfactory sacs; secondly, the space
+which generally intervenes between prosencephalon and mesencephalon, as
+in some Ganoids; thirdly, the large development of the metencephalon.
+
+The hemispheres are generally large, coalescent, but with a median,
+longitudinal, dividing groove. Frequently their surface shows traces
+of gyrations, and when they are provided with lateral ventricles,
+tubercles representing _corpora striata_ may be observed. The
+olfactory pedicles take their origin from the side of the hemispheres,
+and are frequently hollow, and if so, their cavity communicates with
+the ventricle of the hemisphere. The optic lobes are generally smaller
+than the hemispheres, coalescent, and provided with an upper median
+groove like the prosencephalon. At their base a pair of lobi inferiores
+are constant, with the hypophysis and _sacsus vasculosus_ (a
+conglomeration of vascular loops without medullary substance) between
+them.
+
+The cerebellum is very large, overlying a portion of the optic lobes
+and of the sinus rhomboidalis, and is frequently transversely grooved.
+The side-walls of the fourth ventricle, which are formed by the corpora
+restiformia, are singularly folded, and appear as two pads, one on
+each side of the cerebellum (_lobi posteriores_ s. _lobi nervi
+trigemini_).
+
+  [Illustration: Fig. 44.--Brain of Bdellostoma. (Enlarged, after
+  Müller.)
+
+    I., Upper; II., Lower aspect.      Letters as in Fig. 45.]
+
+  [Illustration: Fig. 45.--Brain of Petromyzon. (Enlarged, after
+  Müller.)
+
+  I., Upper; II., Lower aspect.
+
+    _a_, Medulla oblongata; _ac_, nerv. acusticus; _b_, corpus
+    restiforme or rudimentary cerebellum; _d_, lobus ventriculi
+    tertii; _d’_, entrance into the third ventricle; _c_,
+    hypophysis; _fa_, nerv. facialis; _g_, nerv. opticus;
+    _h_, hemisphere; _hy_, nerv. hypoglossus (so named by
+    Müller); _i_, lobus olfactorius; _k_, sinus rhomboidalis;
+    _l_, epiphysis; _m_, nerv. oculo-motorius; _q_, corpora
+    quadrigemina; _tr_, nerv. trigeminus; _tro_, nerv.
+    trochlearis; _v_, nerv. vagus.]
+
+The brain of the _Cyclostomes_ (Figs. 44, 45) represents a type
+different from that of other fishes, showing at its upper surface
+three pairs of protuberances in front of the cerebellum; they are
+all solid. Their homologies are not yet satisfactorily determined,
+parts of the Myxinoid brain having received by the same observers
+determinations very different from those given to the corresponding
+parts of the brain of the Lampreys. The foremost pair are the large
+olfactory tubercles, which are exceedingly large in _Petromyzon_. They
+are followed by the hemispheres, with a single body wedged in between
+their posterior half; in _Petromyzon_, at least, the vascular tissue
+leading to an epiphysis seems to be connected with this body. Then
+follows the lobus ventriculi tertii, distinctly paired in Myxinoids,
+less so in _Petromyzon_. The last pair are the _corpora quadrigemina_.
+According to this interpretation the cerebellum would be absent in
+Myxinoids, and represented in _Petromyzon_ by a narrow commissure
+only (Fig. 45, _b_), stretching over the foremost part of the sinus
+rhomboidalis. In the Myxinoids the _medulla oblongata_ ends in two
+divergent swellings, free and obtuse at their extremity, from which
+most of the cerebral nerves take their origin.
+
+
+The _Nerves_ which supply the organs of the head are either merely
+continuations or diverticula of the brain-substance, or proper nerves
+taking their origin from the brain, or receiving their constituent
+parts from the foremost part of the spinal chord. The number of these
+spino-cerebral nerves is always less than in the higher vertebrates,
+and their arrangement varies considerably.
+
+
+     A. _Nerves which are diverticula of the brain_ (Figs. 41–45).
+
+The _olfactory_ nerves (_first pair_) always retain their intimate
+relation to the hemispheres, the ventricles of which are not rarely
+continued into the tubercle or even pedicle of the nerves. The
+different position of the olfactory tubercle has been already described
+as characteristic of some of the orders of fishes. In those fishes
+in which the tubercle is remote from the brain, the nerve which has
+entered the tubercle as a single stem leaves it split up into several
+or numerous branches, which are distributed in the nasal organ. In
+the other fishes it breaks up into branchlets spread into a fan-like
+expansion at the point, where it enters the nasal cavity. The nerve
+always passes out of the skull through the ethmoid.
+
+The _optic_ nerves (_second pair_) vary in size, their strength
+corresponding to the size of the eye; they take their origin from the
+_lobi optici_, the development of which again is proportionate to that
+of the nerves. The mutual relation of the two nerves immediately after
+their origin is very characteristic of the sub-classes of fishes. In
+the _Cyclostomes_ they have no further connection with each other, each
+going to the eye of its own side.[11] In the _Teleostei_ they simply
+cross each other (_decussate_), so that the one starting from the right
+half of the brain goes to the left eye and _vice versa_. Finally, in
+_Palæichthyes_ the two nerves are fused together, immediately after
+their origin, into a _chiasma_. The nerve is cylindrical for some
+portion of its course, but in most fishes gradually changes this
+form into that of a plaited band, which is capable of separation and
+expansion. It enters the bulbus generally behind and above its axis.
+The foramen through which it leaves the skull of Teleostei is generally
+in a membranous portion of its anterior wall, or, where ossification
+has taken place, in the orbito-sphenoid.
+
+
+         B. _Nerves proper taking their origin from the brain_
+                            (Figs. 41–45).
+
+The _Nervus oculorum motorius_ (_third pair_) takes its origin from
+the Pedunculus cerebri, close behind the lobi inferiores; it escapes
+through the orbito-sphenoid, or the membrane replacing it, and is
+distributed to the musculi rectus superior, rectus internus, obliquus
+inferior, and rectus inferior. Its size corresponds to the development
+of the muscles of the eye. Consequently it is absent in the blind
+_Amblyopsis_, and the Myxinoids. In _Lepidosiren_ the nerves supplying
+the muscles of the eye have no independent origin, but are part of the
+ophthalmic division of the Trigeminus. In _Petromyzon_ these muscles
+are supplied partly from the Trigeminus, partly by a nerve representing
+the Oculo-motor and Trochlearis, which are fused into a common trunk.
+
+The _Nervus trochlearis_ (_fourth pair_), if present with an
+independent origin, is always thin, taking its origin on the upper
+surface of the brain from the groove between lobus opticus and
+cerebellum; it goes to the Musculus obliquus superior of the eye.
+
+
+      C. _Nerves taking their origin from the Medulla oblongata_
+                            (Figs. 41–45).
+
+The _Nervus abducens_ (_sixth pair_) issues on the lower surface of
+the brain, taking its origin from the anterior pyramids of the Medulla
+oblongata, and supplies the Musculus rectus externus of the eye, and
+the muscle of the nictitating membrane of Sharks.
+
+The _Nervus trigeminus_ (_fifth pair_) and the _Nervus facialis_
+(_seventh pair_) have their origins close together, and enter into
+intimate connection with each other. In the Chondropterygians and
+most Teleostei the number of their roots is four, in the Sturgeons
+five, and in a few Teleostei three. When there are four, the first
+issues immediately below the cerebellum from the side of the Medulla
+oblongata; it contains motory and sensory elements for the maxillary
+and suspensorial muscles, and belongs exclusively to the trigeminal
+nerve. The second root, which generally becomes free a little above
+the first, supplies especially the elements for the Ramus palatinus,
+which sometimes unites with parts of the Trigeminal, sometimes with the
+Facial nerve. The third root, if present, is very small, and issues
+immediately in front of the acustic nerve, and supplies part of the
+motor elements of the facial nerve. The fourth root is much stronger,
+sometimes double, and its elements pass again partly into the
+Trigeminal, partly into the Facial nerve. On the passage of these stems
+through the skull (through a foramen or foramina in the alisphenoid)
+they form a ganglionic plexus, in which the palatine ramus and the
+first stem of the Trigeminus generally possess discrete ganglia.
+The branches which issue from the plexus and belong exclusively to
+the Trigeminus, supply the organs and integuments of the frontal,
+ophthalmic, and nasal regions, and the upper and lower jaws with their
+soft parts. The Facial nerve supplies the muscles of the gill-cover
+and suspensorium, and emits a strong branch accompanying the Meckelian
+cartilage to the symphysis, and another for the hyoid apparatus.
+
+The _Nervus acusticus_ (_eighth pair_) is strong, and takes its origin
+immediately behind, and in contact with, the last root of the seventh
+pair.
+
+The _Nervus glossopharyngeus_ (_ninth pair_)[12] takes its origin
+between the roots of the eighth and tenth nerves, and issues in
+Teleostei from the cranial cavity by a foramen of the exoccipital. In
+the Cyclostomes and Lepidosiren it is part of the Nervus vagus. It is
+distributed in the pharyngeal and lingual regions, one branch supplying
+the first branchial arch. After having left the cranial cavity it
+swells into a ganglion, which in Teleostei is always in communication
+with the sympathic nerve.
+
+The _Nervus vagus_ or _pneumogastricus_ (_tenth pair_) rises in
+all Teleostei and Palæichthyes with two discrete strong roots: the
+first constantly from the swellings of the corpora restiformia, be
+they thinner or thicker and overlying the sinus rhomboidalis, or
+be they developed into lateral plaited pads, as in Acipenser and
+Chondropterygians. The second much thicker root rises from the lower
+tracts of the medulla oblongata. Both stems leave the cranial cavity by
+a common foramen, situated in Teleosteous fishes in the exoccipital;
+and form ganglionic swellings, of which those of the lower stem are the
+more conspicuous. The lower stem has mixed elements, motory as well as
+sensory, and is distributed to the muscles of the branchial arches and
+pharynx, the œsophagus and stomach; it sends filaments to the heart and
+to the air-bladder where it exists. The first (upper) stem forms the
+_Nervus lateralis_. This nerve, which accompanies the lateral mucous
+system of the trunk and tail, is either a single longitudinal stem,
+gradually becoming thinner behind, running superficially below the
+skin (Salmonidæ, Cyclopterus), or deeply between the muscles (Sharks,
+Chimæra), or divided into two parallel branches (most Teleostei): thus
+in the Perch there are two branches on each side, the superficial
+of which supplies the lateral line, whilst the deep-seated branch
+communicates with the spinal nerves and supplies the septa between the
+myocommas and the skin. In fishes which lack the lateral muciferous
+system and possess hard integuments, as the Ostracions, the lateral
+nerve is more or less rudimentary. It is entirely absent in Myxinoids,
+but the gastric branches of the Vagus are continued, united as a single
+nerve, along the intestine to the anus.
+
+No fish possesses a _Nervus accessorius_. Also a separate _Nervus
+hypoglossus_ (_twelfth pair_)[13] is absent, but elements from the
+first spinal nerve are distributed in the area normally supplied by
+this nerve in higher vertebrates.
+
+       *       *       *       *       *
+
+The number of _Spinal_ nerves corresponds to that of the vertebræ,
+through or between which they pass out. Each nerve has two roots,
+an anterior and posterior, the former of which has no ganglion, and
+exclusively contains motor elements. The posterior or dorsal has a
+ganglionic enlargement, and contains sensory elements only. After
+leaving the vertebral canal each spinal nerve usually divides into
+a dorsal and ventral branch. The Gadoids show that peculiarity that
+each of the posterior roots of some or many of the spinal nerves
+possesses two separate threads, each of which has a ganglion of its
+own; the one of these threads joins the dorsal and the other the
+ventral branch. In fishes in which the spinal chord is very short, as
+in Plectognaths, Lophius, the roots of the nerves are extremely long,
+forming a thick _Cauda equina_. The additional function which
+the (five) anterior spinal nerves of _Trigla_ have to perform
+in supplying the sensitive pectoral appendages and their muscles has
+caused the development of a paired series of globular swellings of the
+corresponding portion of the spinal chord. A similar structure is found
+in _Polynemus_.
+
+  [Illustration: Fig. 46.
+
+   Brain and anterior portion of the spinal chord of Trigla
+   (Gurnard), showing the globular swellings at the base of the
+   anterior spinal nerves.]
+
+A _Sympathic nervous_ system appears to be absent in _Branchiostoma_,
+and has not yet been clearly made out in _Cyclostomes_. It is well
+developed in the _Palæichthyes_, but without cephalic portion. This
+latter is present in all Osseous fishes, in which communication of the
+Sympathic has been found to exist with all cerebral nerves, except the
+olfactory, optic, and acustic. The sympathic trunks run along each
+side of the aorta and the back of the abdomen into the hæmal canal;
+communicate in their course with the ventral branches of each of the
+spinal nerves; and, finally, often blend together into a common trunk
+beneath the tail. At the points of communication with the cerebral
+and spinal nerves frequently ganglia are developed, from which nerves
+emerge which are distributed to the various viscera.
+
+
+
+
+                             CHAPTER VII.
+
+                         THE ORGANS OF SENSE.
+
+
+Characteristic of the _Organ of Smell_ in Fishes is that it has
+no relation whatever to the respiratory function, with the exception
+of the _Dipnoi_, in which possibly part of the water received for
+respiration passes through the nasal sac.
+
+The olfactory organ is single in _Branchiostoma_ and the _Cyclostomes_.
+In the former a small depression on the front end of the body, clothed
+with a ciliated epithelium, is regarded as a rudimentary organ of
+smell. In the adult _Petromyzon_ a membranous tube leads from the
+single opening on the top of the head into the cartilaginous olfactory
+capsule, the inside of which is clothed by membranes prolonged into a
+posterior blind tube (Fig. 30, _s_), which penetrates the cartilaginous
+roof of the palate, but not the mucous membrane of the buccal cavity.
+In the Myxinoids the outer tube is strengthened by cartilaginous
+rings like a trachea; the capsule is lined by a longitudinally folded
+pituitary membrane, and the posterior tube opens backwards on the roof
+of the mouth; the opening is provided with a valve.
+
+In all other Fishes the organ of smell is double, one being on each
+side; it consists of a sac lined with a pituitary membrane, and
+without, or with one or two, openings. The position of these openings
+is very different in the various orders or suborders of Fishes.
+
+In the _Dipnoi_ the nasal sac opens downwards by two wide openings
+which are within the boundaries of the cavity of the mouth. The
+pituitary membrane is transversely folded, the transverse folds being
+divided by one longitudinal fold. The walls of the sac are strengthened
+by sundry small cartilages.
+
+Also in _Chondropterygians_ the openings, of which there is one
+to each sac, are on the lower part of the snout, and in the Rays,
+Holocephali, and some Sharks, each extends into the cleft of the mouth.
+The openings are protected by valvular flaps, supported by small
+cartilages, and moved by muscles, whence it may be concluded that these
+fishes are able to scent (actively) as well as to smell (passively).
+
+  [Illustration: Fig. 47.--Nostrils of _Raia lemprieri_, with
+  nasal flaps reverted.]
+
+In the majority of _Teleostei_ the olfactory capsules are lateral or
+superior on the snout, covered externally by the skin, each usually
+pierced by two openings, which are either close together, or more
+or less remote from each other; the posterior is generally open,
+the anterior provided with a valve or tube. In the _Chromides_ and
+_Labroidei ctenoidei_ a single opening only exists for each sac. In
+the _Murænidæ_ the two openings of each side are either superior, or
+lateral, or labial, that is, they are continued downwards and pierce
+the margin of the upper lip. In many Tetrodonts nasal openings are
+absent, and replaced by a conical papilla, in which the olfactory nerve
+terminates.
+
+It is certain that fishes possess the faculty of perceiving odours,
+and that various scents attract or repel them. A mangled carcase
+or fresh blood attracts Sharks as well as the voracious Serrasal
+monoids of the South American rivers. There is no reason to doubt that
+the seat of that perception is in the olfactory sac; and it may be
+reasonably conjectured that its strength depends mainly on the degree
+of development indicated by the number and extent of the interior folds
+of the pituitary membrane.
+
+_Organ of Sight_.--The position, direction, and dimensions of the
+eyes of fishes vary greatly. In some they have an upward aspect, and
+are often very close together; in others they are lateral, and in a
+few they are even directed downwards. The Flat-fishes represent the
+extraordinary anomaly that both eyes are on the same side of the head,
+and rarely on the same level, one being generally placed more forward
+than the other. In certain species of marine fishes the eyes are of
+an extraordinary size, a peculiarity indicating that the fish either
+lives at a great depth, to which only a small proportion of the rays
+of light penetrate, or that it is of nocturnal habits. In fishes which
+have descended to such great depths that no rays whatever can reach
+them, or in freshwater fishes living in caves, or in species which
+grovel and live constantly in mud, the eyes are more or less aborted,
+sometimes quite rudimentary, and covered by the skin. In very few this
+organ appears to be entirely absent. In some Gobioids and Trachinoids
+(_Periophthalmus_, _Boleophthalmus_, _Uronoscopus_, etc.) the eyes,
+which are on the upper side of the head, can be elevated and depressed
+at the will of the fish. In the range of their vision and acuteness of
+sight, Fishes are very inferior to the higher classes of Vertebrates,
+yet at the same time it is evident that they perceive their prey or
+approaching danger from a considerable distance; and it would appear
+that the visual powers of a _Periophthalmus_, when hunting insects on
+mud-flats of the tropical coasts, are quite equal to that of a frog.
+Again, the discrimination with which fishes sometimes prefer one colour
+or kind of artificial fly to another affords sufficient evidence
+that the vision, at least of certain species is by no means devoid of
+clearness and precision.
+
+The eye of _Branchiostoma_ is of the most rudimentary condition. It is
+simply a minute speck coated by dark pigment, and receiving the end of
+a short nerve. In _Myxinoids_ the minute rudiment of the eye is covered
+by the skin and muscles. This is also the case in many of the blind
+Teleosteous fishes; however, whilst in the former fishes the organ of
+sight has not attained to any degree of development, the rudimentary
+eye of blind Teleostei is a retrogressive formation, in which often
+a lens and other portions of the eye can be recognised. In fishes
+with a well-developed eye it is imbedded in a layer of gelatinous and
+adipose substance, which covers the cavity of the orbit. A lacrymal
+gland is absent. In the orbit of one fish only, _Chorismodentex_, an
+organ has been found which can be compared to a _saccus lacrymalis_.
+It is a round, blind, wide sac, of the size of a pea, situated below
+the anterior corner of the orbit, between the maxillary bone and the
+muscles of the cheek, communicating by a rather wide foramen with
+the orbital cavity. The membrane by which it is formed is continuous
+with that coating the orbita. In the Chondropterygians the eyeball is
+supported by and moves on a cartilaginous peduncle of the orbital wall.
+In the majority of Teleosteans, and in Acipenser, a fibrous ligament
+attaches the sclerotic to the wall of the orbit. The proper muscles
+of the eyeball exist in all fishes, and consist of the four _Musculi
+recti_ and the two _M. obliqui_. In many Teleostei the former rise
+from a subcranial canal, the origin of the _M. rectus externus_ being
+prolonged farthest backwards. The _Recti_ muscles are extraordinarily
+long in the Hammerheaded Sharks, in which they extend from the basis
+cranii along the lateral prolongations of the head to the eyes, which
+are situated at the extremities of the hammer.
+
+In all fishes the general integument of the head passes over the
+eye, and becomes transparent where it enters the orbit; sometimes it
+simply passes over the orbit, sometimes it forms a circular fold. The
+anterior and posterior portions may be especially broad and the seat
+of an adipose deposit (_adipose eyelids_), as in _Scomber_, _Caranx_,
+_Mugil_, etc. In many of these fishes the extent of these eyelids
+varies with the seasons; during the spawning season they are so much
+loaded with fat as nearly to hide the whole eye. Many Sharks possess a
+_nictitating_ membrane, developed from the lower part of the palpebral
+fold, and moved by a proper set of muscles.
+
+  [Illustration: Fig. 48.
+
+   Vertical section through eye of Xiphias. (After Owen.)
+
+    _co_, Cornea; _sc_, sclerotica; _o_, nervus opticus; _c_,
+    sclerotic capsule; _a_, membrana argentea; _v_, membrana
+    vasculosa; _u_, membrana uvea; _ch_, choroid gland; _r_,
+    retina; _f_, processus falciformis; _h_, humor vitreus; _l_,
+    lens; _i_, iris.]
+
+The form of the _bulbus_ (Fig. 48) is subhemispherical, the cornea
+(_co_) being flat. If it were convex, as in higher Vertebrates, it
+would be more liable to injury; but being level with the side of the
+head the chances of injury by friction are diminished. The _sclerotica_
+(_sc_) is cartilaginous in Chondropterygians and Acipensers, fibrous
+and of varying thickness in Teleosteans, in the majority of which it
+is supported by a pair of cartilaginous or ossified hemispheroid cups
+(_c_). In a few fishes, as in _Ceratodus_, _Xiphias_, the cups are
+confluent into one cup, which possesses a foramen behind to allow the
+passage of the optic nerve (_o_). The _cornea_ of _Anableps_ shows an
+unique peculiarity. It is crossed by a dark horizontal stripe of the
+conjunctiva, dividing it into an upper and lower portion; also the iris
+is perforated by two pupils. This fish is observed to swim frequently
+with half of its head out of the water, and it is a fact that it can
+see out of the water as well as in it.
+
+The membranes situated between the sclerotica and retina are
+collectively called _choroidea_, and three in number. The one in
+immediate contact with the sclerotic, and continued upon the iris,
+is by no means constantly present; it is the _membrana argentea_
+(_a_), and composed of microscopical crystals reflecting a silvery or
+sometimes golden lustre. The middle layer is the _membrana vasculosa_
+s. _halleri_ (_v_), the chief seat of the ramifications of the choroid
+vessels; the innermost layer is the _membrana ruyscheana_ or _uvea_
+(_u_), which is composed of hexagonal pigment-cells, usually of a deep
+brown or black colour.
+
+In many _Teleostei_ a _rete mirabile_ surrounds the entry of the optic
+nerve; it is situated between the membrana argentea and vasculosa, and
+called the _choroid gland_ (_ch_). It receives its arterial blood from
+the artery issuing from the pseudobranchia; the presence of a choroid
+gland always being combined with that of a pseudobranchia. Teleosteans
+without pseudobranchia lack a choroid gland. In the Palæichthyes, on
+the other hand, the pseudobranchia is present and a choroid gland
+absent.
+
+The _iris_ (_i_) is merely the continuation of the choroid membrane;
+its capability of contracting and expanding is much more limited than
+in higher Vertebrates. The _pupil_ is generally round, sometimes
+horizontally or vertically elliptical, sometimes fringed. In the
+Rays and Pleuronectidæ a lobe descends from the upper margin of the
+pupil, and the outer integument overlying this lobe is coloured and
+non-transparent; a structure evidently preventing light from entering
+the eye from above.
+
+In most _Teleostei_ a fold of the _Choroidea_, called the _Processus
+falciformis_ (_f_), extends from the vicinity of the entrance of the
+optic nerve to the lens. It seems to be constantly absent in Ganoids.
+
+The _retina_ (_r_) is the membrane into which the optic nerve
+penetrates, and in which its terminal filaments are distributed. It
+consists of several layers (Fig. 49). The outermost is an extremely
+delicate membrane (_a_), followed by a layer of nerve-cells (_b_), from
+which the terminal filaments issue, passing through several granular
+strata (_c_, _d_, _e_), on which the innermost stratum rests. This
+stratum is composed of cylindrical rods (_f_) vertically arranged,
+between which twin fusiform corpuscles (_g_) are intercalated. This
+last layer is thickly covered with a dark pigment. The retina extends
+over a portion of the iris, and a well-defined raised rim runs along
+its anterior margin.
+
+  [Illustration: Fig. 49.--Vertical section of the Retina of the
+  Perch, magn. X 350.]
+
+The _vitreous humour_ (Fig. 48, _h_) which fills the posterior
+cavity of the eyeball, is of a firmer consistency than in the higher
+Vertebrates. The _lens_ is spherical, or nearly so; firm, denser
+towards the centre, and lies in a hollow of the vitreous humour. When
+a falciform process is present, it is with one end attached to the
+lens, which is thus steadied in its position. It consists of concentric
+layers consisting of fibres, which in the nucleus of the body have
+marginal teeth, by which they are interlocked together. In _Petromyzon_
+this serrature is absent, or but faintly indicated.
+
+  [Illustration: Fig. 50.--Interlocking fibres of lens, highly
+  magnified.]
+
+The anterior cavity of the eye is very small in Fishes, in consequence
+of the small degree of convexity of the cornea; the quantity of the
+aqueous humour, therefore, is very small, just sufficient to float the
+free border of the iris; and the lessened refractive power of the
+aqueous humour is compensated by the greater convexity of the lens.
+
+       *       *       *       *       *
+
+_Organ of Hearing._--No trace of an organ of hearing has been found
+in _Branchiostoma_. In the _Cyclostomes_ the labyrinth is enclosed in
+externally visible cartilaginous capsules laterally attached to the
+skull; it consists of a single _semicircular canal_ in the Myxinoids,
+whilst the Petromyzontes possess two semicircular canals with a
+_vestibulum_.
+
+In all other fishes the labyrinth consists of a vestibule and three
+semicircular canals, the vestibule dilating into one or more sacs which
+contain the otoliths. A tympanum, tympanic cavity, and external parts,
+are entirely absent in the class of fishes.
+
+In the _Chondropterygians_ and _Dipnoi_, the labyrinth is enclosed in
+the cartilaginous substance of the skull. In the former the excavation
+in the cartilage is larger than the membranous labyrinth, but nearly
+corresponds to it in form; the part which receives the membranous
+vestibulum is called _Vestibulum cartilagineum_, from which a canal
+issues and penetrates to the surface of the skull, where it is closed
+by the skin in Sharks, but opens by a minute foramen in Rays. The
+otolithic contents are soft and chalklike.
+
+In the _Holocephali_ part of the labyrinth is enclosed in the cartilage
+of the skull, another part being in the cranial cavity, as in Ganoids
+and Teleosteans. The membranous vestibulum is continued by a canal to a
+single opening in the roof of the skull, from which two smaller canals
+are continued to two small foramina in the skin covering the occipital
+region.
+
+In the _Teleosteans_ the sac which contains the otoliths lies on each
+side of the base of the cranial cavity and is often divided by a septum
+into two compartments of unequal size, each containing a firm and solid
+_otolith_; these bodies (Fig. 51), possess indented margins, frequently
+other impressions and grooves, in which nerves from the N. acusticus
+are lodged; they vary much in size and form, but in both respects show
+a remarkable constancy in the same kind of fishes. The vestibule is
+outwards in contact with the osseous side wall of the skull, inwards
+with the metencephalon and medulla oblongata; it contains another firm
+concretion, and opens by five foramina into the three semicircular
+canals. The terminations of the acustic nerve are distributed over the
+vestibular concretion and the ampulliform ends (Fig. 52 _p_) of the
+semicircular canals, without being continued into the latter, which are
+filled with fluid. The semicircular canals (Fig. 52 _g_), are sometimes
+lodged in the cranial bones, sometimes partly free in the cranial
+cavity. Many Teleostei have fontanelles in the roof of the skull,
+closed by skin or very thin bone only at the place where the auditory
+organ approaches the surface, by which means sonorous undulations must
+be conducted with greater ease to the ear.
+
+  [Illustration:
+
+   Fig. 51.--Otolith of Haddock (Gadus æglefinus). I. Outer, II.
+   Inner aspect.]
+
+In many Teleostei a most remarkable relation obtains between the organ
+of hearing and the air-bladder. In the most simple form this connection
+is established in Percoids and the allied families, in which the two
+anterior horns of the air-bladder are attached to fontanelles of the
+occipital region of the skull, the vestibulum occupying the opposite
+side of the membrane by which the fontanelle is closed. The condition
+is similar, but more complicated in many Clupeoids. The anterior narrow
+end of the air-bladder is produced into a canal at the base of the
+skull, and divided into two very narrow branches, which again bifurcate
+and terminate in a globular swelling. An appendage of the vestibulum
+meets the anterior of these swellings, and comes into close contact
+with it. Besides, the two vestibules communicate with each other by a
+transverse canal, crossing the cranial cavity below the brain.
+
+  [Illustration: Fig. 52.--Communication between auditory organ and
+  air-bladder in the Carp. (After E. H. Weber.)
+
+    _a_, Basisphenoid; _b_, Occipital; _c_, Supraoccipital;
+    _d_, Exoccipital; _e_, Paroccipital; _f_, Alisphenoid; _g_,
+    Neural arch of first vertebra; _h_, _i_, _k_, second, third,
+    and fourth vertebra; _h_’, _i_’, Parapophyses of second and
+    third vertebra; _i_", process of the third vertebra for
+    the attachment of the air-bladder; _k_, _l_, _m_, Chain
+    of ossicles; _n_, Air-bladder; _o_, vestibulum; _p_, _p_,
+    Ampullæ; _q_, _q_, Canales semicirculares; _r_, Sinus impar.]
+
+The connection is effected by means of a chain of ossicles in
+_Siluridæ_, _Characinidæ_, _Cyprinidæ_ and _Gymnotidæ_. A canal issues
+from the communication between vestibule and its sac, and meeting that
+from the other side forms with it a common _sinus impar_ (Fig. 52,
+_r_), lodged in the substance of the basi-occipital; this communicates
+on each side by a small orifice with two subspherical atria, on
+the body of the atlas, close to the foramen magnum. Each atrium is
+supported externally by a small bone (_m_); a third larger bone (_k_)
+completes the communication with the anterior part of the air-bladder.
+From the sinus impar a bifid canal penetrates into the alisphenoids,
+in which it terminates. In _Cobitis_ and several Loach-like Siluroids
+the small air-bladder consists of two globular portions placed side
+by side, and wholly included within two bullæ, formed by the modified
+parapophyses of the second and third vertebræ. The three ossicles on
+each side are present, but concealed by the fore part of the osseous
+bulla.
+
+       *       *       *       *       *
+
+_Organ of Taste._--Some fishes, especially vegetable feeders, or those
+provided with broad molar-like teeth, masticate their food; and it
+may be observed in Carps and other Cyprinoid fish, that this process
+of mastication frequently takes some time. But the majority of fish
+swallow their food rapidly, and without mastication, and therefore we
+may conclude that the sense of taste cannot be acute. The tongue is
+often entirely absent, and even when it exists in its most distinct
+state, it consists merely of ligamentous or cellular substance, and
+is never furnished with muscles capable of producing the movements of
+extension or retraction as in most higher Vertebrates. A peculiar organ
+on the roof of the palate of Cyprinoids, is perhaps an organ adapted
+for perception of this sense; in these fishes the palate between and
+below the upper pharyngeal bones is cushioned with a thick, soft
+contractile substance, richly supplied with nerves from the Nervi vagus
+and glossopharyngeus.
+
+_Organs of Touch._--The faculty of touch is more developed than that of
+taste, and there are numerous fishes which possess special organs of
+touch. Most fishes are very sensitive to external touch, although their
+body may be protected by hard horny scales. They perceive impressions
+even on those parts which are covered by osseous scutes, in the same
+manner as a tortoise perceives the slightest touch of its carapace. The
+seat of the greatest sensitiveness, however, appears to be the snout
+and the labial folds surrounding the mouth. Many species possess soft
+and delicate appendages, called barbels, which are almost constantly
+in action, and clearly used as organs of touch. Among the _Triglidæ_
+and allied families, there are many species which have one or more
+rays of the pectoral fin detached from the membrane, and supplied with
+strong nerves. Such detached rays (also found in the _Polynemidæ_,
+_Bathypterois_) are used partly for locomotion, partly for the purpose
+of exploring the ground over which the fish moves.
+
+Some fish appear to be much less sensitive than others, or at least
+lose their sensitiveness under peculiar circumstances. It is well known
+that a Pike, whose mouth has been lacerated and torn by the hook,
+continues to yield to the temptation of a bait immediately afterwards.
+The Greenland Shark when feeding on the carcass of a whale allows
+itself to be repeatedly stabbed in the head without abandoning its
+prey. A pair of Congers are so dead to external impression at the time
+of copulation, and so automatically, as it were, engaged, that they
+have been taken by the hand together out of the water.
+
+
+
+
+                             CHAPTER VIII.
+
+                THE ORGANS OF NUTRITION AND DIGESTION.
+
+
+Fishes are either exclusively carnivorous or herbivorous, but not a few
+feed on vegetable substances as well as animal, or on mud containing
+alimentary substance in a living or decomposing state. Generally they
+are very voracious, especially the carnivorous kinds, and the rule of
+“eat or be eaten” applies to them with unusual force. They are almost
+constantly engaged in the pursuit and capture of their prey, the
+degree of their power in these respects depending on the dimensions
+of the mouth and gullet and the strength of the teeth and jaws. If
+the teeth are sharp and hooked, they are capable of securing the most
+slender and agile animals; if this kind of teeth is combined with a
+wide gullet and distensible stomach, they are able to overpower and
+swallow other fish larger than themselves; if the teeth are broad,
+strong molars, they are able to crush the hardest aliments; if they
+are feeble, they are only serviceable in procuring some small or inert
+and unresisting prey. Teeth may be wanting altogether. Whatever the
+prey, in the majority of cases it is swallowed whole; but some of the
+most voracious fishes, like some Sharks and _Characinidæ_, are
+provided with cutting teeth, which enable them to tear their prey to
+pieces if too large to be swallowed whole. Auxiliary organs for the
+purpose of overpowering their prey, which afterwards is seized or torn
+by the teeth, like the claws of some carnivorous mammals and birds, are
+not found in this class; but in a few fishes the jaws themselves are
+modified for that purpose. In the Sword-fishes the bones of the upper
+jaw form a long dagger-shaped weapon, with which they not only attack
+large animals, but also frequently kill fishes on which they feed.
+The Saw-fishes are armed with a similar but still more complicated
+weapon, the saw, which is armed on each side with large teeth implanted
+in deep sockets, specially adapted for killing and tearing the prey
+before it is seized and masticated by the small teeth within the mouth.
+Fishes show but little choice in the selection of their food, and some
+devour their own offspring indiscriminately with other fishes. Their
+digestive powers are strong and rapid, but subject in some degree to
+the temperature, which, when sinking below a certain point, lowers the
+vital powers of these cold-blooded animals. On the whole, marine fishes
+are more voracious than those inhabiting fresh waters; and whilst the
+latter may survive total abstinence from food for weeks or months,
+the marine species succumb to hunger within a few days. The growth of
+fishes depends greatly on the nature and supply of food, and different
+individuals of the same species may exhibit a great disparity in their
+respective dimensions. They grow less rapidly and to smaller dimensions
+in small ponds or shallow streams than in large lakes and deep rivers.
+The young of coast fishes, when driven out to sea, where they find
+a much smaller supply of food, remain in an undeveloped condition,
+assuming an hydropic appearance. The growth itself seems to continue
+in most fishes for a great length of time, and we can scarcely set
+bounds to--certainly we know not with precision--the utmost range of
+the specific size of fishes. Even among species in no way remarkable
+for their dimensions we sometimes meet with old individuals, favourably
+situated, which more or less exceed the ordinary weight and measurement
+of their kind. However, there are certain evidently short-lived species
+of fishes which attain a remarkably uniform size within a very short
+time; for instance, the Stickleback, many species of _Gobius_ and
+_Clupea_.
+
+       *       *       *       *       *
+
+The organs of nutrition, manducation, and deglutition, are lodged in
+two large cavities--an anterior (the mouth or _buccal cavity_), and
+a posterior (the _abdominal cavity_). In the former the alimentary
+organs are associated with those fulfilling the respiratory functions,
+the transmission of food to the stomach and of water to the gills
+being performed by similar acts of deglutition. The abdominal cavity
+commences immediately behind the head, so, however, that an extremely
+short thoracic cavity for the heart is partitioned off in front. Beside
+the alimentary organs it contains also those of the urogenital system
+and the air-bladder. The abdominal cavity is generally situated in the
+trunk only, but in numerous fishes it extends into the tail, being
+continued for some distance along each side of the hæmal apophyses.
+
+In numerous fishes the abdominal cavity opens outwards by one or two
+openings. A single _porus abdominalis_ in front of the vent is found
+in _Lepidosiren_ and some Sturgeons; a paired one, one on each side
+of the vent, in _Ceratodus_, some species of Sturgeon, _Lepidosteus_,
+_Polypterus_, _Amia_, and all Chondropterygians. As in these fishes
+semen and ova are discharged by proper ducts, the abdominal openings
+may serve for the expulsion of semen, and those ova only which, having
+lost their way to the abdominal aperture of the oviduct, would be
+retained in the abdominal cavity. In those _Teleosteans_ which lack an
+oviduct a single _porus genitalis_ opens _behind_ the vent.
+
+The _mouth_ of fishes shows extreme variation with regard to form,
+extent, and position. Generally opening in front, it may be turned
+upwards, or may lie at the lower side of the snout, as in most
+Chondropterygians, Sturgeons, and some Teleosteans. Vogt regards this
+position as a persistent fœtal condition. In most fishes the jaws are
+covered by the skin, which, before passing over the jaws, is often
+folded, forming more or less fleshy lips. In the Sharks the skin
+retains its external character even within the teeth, but in other
+fishes it changes into a mucous membrane. A _tongue_ may exist as a
+more or less free and short projection, formed by the glosso*-hyal and
+a soft covering, or may be entirely absent. _Salivary_ glands and a
+_velum palati_ are absent in fishes.
+
+With regard to the _dentition_, the class of Fishes offers an amount
+of variation such as is not found in any of the other classes of
+Vertebrates. As the teeth form one of the most important elements in
+the classification of fishes, their special arrangement and form will
+be referred to in the account of the various families and genera.
+Whilst not a few fishes are entirely edentulous, in others most of the
+bones of the buccal cavity, or some of them, may be toothed, as the
+bones of the jaws, the palatines, pterygoids, vomers, basisphenoid,
+glossohyal, branchial arches, upper and lower pharyngeals. In others
+teeth may be found fixed in some portion of the buccal membrane without
+being supported by underlying bone or cartilage; or the teeth have
+been developed in membrane overlying one of the dentigerous bones
+mentioned, without having become anchylosed to the bone. When the tooth
+is fixed to the bone the attachment has generally been effected by the
+ossification of the bone of the tooth, but in some fishes a process of
+the bone projects into the cavity of the tooth; in others the teeth are
+implanted in alveoli. In these, again, frequently a process of bone
+rises from the bottom, on which the tooth rests.
+
+Many fishes, especially predatory fishes with long, lancet-shaped
+teeth, have all or some of the teeth capable of being bent inwards
+towards the mouth. Such “hinged” teeth resume at once the upright
+position when pressure is removed from them. They are, however,
+depressible in one direction only, thus offering no obstacle to the
+ingress, but opposing the egress of prey. Mr. C. S. Tomes has shown
+that the means by which this mechanism is worked are different in
+different fishes; for whilst, in the _Pediculati_ and _Gadoids_ (Hake)
+the elasticity resides solely in the tissue of the hinge (the tooth
+being as resilient as ever after everything else is severed), in the
+Pike the hinge is not in the least endowed with elasticity, but the
+bundles of fibres proceeding from the interior of the dentine cap are
+exceedingly elastic.
+
+As regards texture the teeth of fishes show considerable variation.
+The conical teeth of the Cyclostomes and the setiform teeth of many
+Teleosteans consist of a horny albuminous substance. The principal
+substance of the teeth of other fishes consists of dentine, with
+numerous dividing and anastomosing tubercles, sometimes covered by
+a stratum of unvascular dentine. An enamel-like substance has been
+observed on the crown of the teeth of _Sargus_ and _Balistes_, and an
+ossification of the capsule of their matrix covers the enamel with a
+thin coating of cement. The teeth either possess a cavity in which the
+matrix is received, or, more frequently, they are solid, in which case
+vascular canals of the underlying bone are continued into the substance
+of the tooth. In the teeth of some fishes numerous sets of canals and
+tubes are so arranged that they do not anastomose with one another,
+each set being surrounded by a layer of dentine and cement. These
+apparently simple teeth are evidently composed of numerous small teeth,
+and called _compound_ teeth.
+
+The teeth may be, and generally are, very different as regards size or
+form in the different parts of the mouth; they may be also different
+according to the age or sex of the fish (_Raja_). The teeth may be few
+in number and _isolated_, or placed in a single, double, or triple
+_series_, _distant_ from one another or _closely set_; they may form
+narrow or broad _bands_, or _patches_ of various forms. As regards
+form, they may be cylindrical or conical, pointed, straight, or curved,
+with or without an angular bent near their base; some are compressed
+laterally or from the front backwards; the latter may be triangular
+in shape, or truncated at the top like incisors of mammals; they may
+have one apex (cusp) only, or be bi- or tri-lobate (bi- or tri-cuspid);
+or have the margins denticulated or serrated. Compressed teeth may be
+confluent, and form a cutting edge in both jaws, which assume the shape
+of a parrot’s beak (Fig. 53). In some the apex is hooked or provided
+with barbs. Again, some teeth are broad, with flat or convex surface,
+like molar teeth. With regard to size, the finest teeth are like fine
+flexible bristles, _ciliiform_ or _setiform_; or, if very short and
+anchylosed to the bone, they appear only as inconspicuous asperities
+of the bone. Very fine conical teeth arranged in a band are termed
+_villiform_ teeth; when they are coarser, or mixed with coarser teeth,
+they are _card-like_ (dents en rape or en cardes) (Fig. 54); molar-like
+teeth of very small size are termed _granular_.
+
+  [Illustration: Fig. 53.--Jaws of Calliodon.]
+
+In all fishes the teeth are constantly shed or renewed during the
+whole course of their life. In fishes which have compound teeth, as
+the Dipnoi, Chimæroids, Scari,[14] Gymnodonts, as well as in those
+which have apparently permanent teeth, as in the saw of _Pristis_,
+the detrition of the surface is made up by a constant growth of the
+tooth from its base. When the teeth are implanted in alveoli, they
+are generally succeeded by others in the vertical direction, but in
+others they succeed one another, side by side. In the majority of
+fishes the new tooth is not developed (as in reptiles and mammals) in
+a diverticulum of the sack of its predecessor, but like this from the
+free surface of the buccal membrane. Generally there are more than one
+tooth growing, which are in various stages of development, and destined
+to replace the one in function. This is very conspicuous in Sharks,
+in which the whole phalanx of their numerous teeth is ever marching
+slowly forwards (or in some backwards), in rotatory progress, over the
+alveolar border of the jaw, the teeth being successively cast off after
+having reached the outer margin, and fulfilled for a longer and shorter
+period their special function.
+
+   [The richest materials for our knowledge of the teeth of fishes
+   are contained in _Owen’s_ “Odontography.” Lond. 1840. 8vo.]
+
+  [Illustration: Fig. 54.--Cardlike teeth of Plectropoma dentex,
+  with canines.]
+
+The _intestinal tract_ is divided into four portions: œsophagus,
+stomach, small and large intestine; two or more of these divisions
+may coalesce in fishes and become indistinguishable. But it is
+characteristic of the class that the urinary apertures are constantly
+situated behind the termination of the intestinal tract.
+
+In _Branchiostoma_ the whole intestinal tract is straight, and
+coated with a ciliated mucous membrane. The wide pharynx passes into a
+narrow œsophagus, this into a gastric cavity, the remainder being again
+narrower and terminating in the anal aperture, which lies somewhat
+to the left of the median line. The liver is represented by a green
+coloured cœcal diverticulum of the stomachic dilatation. A mesenterium
+is absent.
+
+In the _Cyclostomi_ the intestinal tract is likewise straight, and
+without clearly defined divisions; however, in _Petromyzon_ the
+œsophagus shows numerous longitudinal folds, and the intestine proper
+is provided with a single longitudinal fold. A mesentery, which is
+present in the Myxinoids, is represented by a short median fold only,
+by means of which the hindmost part of the intestine is fixed.
+
+The _Palæichthyes_ show differences in the structure of their
+intestinal tract as considerable as are found among the _Teleostei_,
+but they have that in common that the absorbent surface of their
+intestine is enlarged by the development of a spiral valve, evidence
+of the presence of which in extinct Palæichthyes is still preserved in
+the fossilised fæces or _coproliths_, so abundant in some of the older
+strata.
+
+In _Chondropterygians_ (Fig. 55) the stomach is divided into a cardiac
+and pyloric portion, the former frequently terminating in a blind
+sac, and the latter varying in length. The pyloric portion is bent
+at its origin and end, and separated from the short duodenum (called
+_Bursa entiana_ in these fishes) by a valve; the ductus hepaticus and
+pancreaticus enter the duodenum. This is succeeded by the straight
+intestine provided with the spiral valve, the coils of which may
+be either longitudinal and wound vertically about the axis of the
+intestine, as in _Carcharias_, _Galeocerdo_, _Thalassorhinus_, and
+_Zygœna_, or they may be transverse to that axis, as in the other
+genera. The number of gyrations in the latter case varies: there may be
+as many as forty. The short rectum passes into a cloaca, which contains
+also the orifices of the urogenital ducts. Only the commencement and
+end of the intestinal tract are fixed by mesenterial folds.
+
+In the _Holocephali_ and _Dipnoi_, the intestinal tract is short,
+straight, and wide, without stomachic dilatation, a pyloric valve,
+close to which the ductus choledochus enters, indicating the boundary
+of the intestine proper (Fig. 57, _p_). The spiral valve is perfect,
+and makes from three (_Chimæra_) to nine (_Ceratodus_) gyrations. A
+cloaca is present, as in Chondropterygians. A mesentery fixing the
+dorsal side of the intestine is absent.
+
+  [Illustration: Fig. 55.--Siphonal stomach and spiral valve of
+  Basking-Shark (Selache). (After Home and Owen.)
+
+    _a_, Œsophagus; _b_, Cardiac portion of stomach; _c_,
+    pyloric portion; _d_, pouch intermediate between stomach and
+    duodenum, with circular valves at both ends; _e_, Duodenum;
+    _f_, Valve of intestine; _g_, Ductus hepaticus; _h_, Spleen.]
+
+The other _Ganoids_ resemble again more the Chondropterygians
+in the structure of their intestinal tract. The stomach has always a
+distinct pyloric portion, and has a still more complicated structure
+in _Acipenser_. The duodenal portion receives the contents of
+_Appendices pyloricæ_, which are confluent into a gland-like mass
+in _Acipenser_, but separate in _Polyodon_, and numerous and
+short in _Lepidosteus_, whilst _Polypterus_ possesses one
+such appendage only. A spiral valve is developed in the Sturgeons and
+Polypterus, but in _Amia_, in which the intestine performs several
+convolutions, the four gyrations of the valve are situated far back
+towards the end of the intestine. In _Lepidosteus_ the valve is
+rudimentary, and indicated only by three raised lines crossing the
+terminal portion of the intestine. In all these Ganoids the rectum has
+a separate opening, without cloaca.
+
+The structure of the intestinal tract of _Teleosteous_ fishes is
+subject to so numerous modifications that we should go beyond the
+limits of the present work if we would attempt to enter into details.
+Great differences in this respect may be found even in groups of the
+same natural families. Frequently the intestinal tract remains of
+nearly the same width throughout its course, and only the entrance
+of the various ducts serves as a guide for the distinction of its
+divisions. An intestine of such uniform width may be straight and
+short, as in _Scombresocidæ_, _Symbranchidæ_, or it may be more or less
+convoluted and long, as in many _Cyprinidæ_, _Doradina_, etc. On the
+whole, carnivorous fishes have a much shorter and simpler intestinal
+tract than herbivorous.
+
+In the majority of Teleosteans, however, œsophagus, stomach, duodenum,
+small intestine and rectum, can be more or less distinctly, even
+externally distinguished.
+
+There are two predominant forms of the stomach, intermediate forms
+being, however, numerous. In the first, the _siphonal_, it
+presents the form of a bent tube or canal, one-half of the horse-shoe
+being the cardiac, the other the pyloric portion. In the second, the
+_cæcal_, the cardiac division is prolonged into a long descending
+blind sac, the cardiac and pyloric openings of the stomach lying close
+together (_Clupea_, _Scomber_, _Thynnus_, etc.)
+
+  [Illustration: Fig. 56.--Siphonal Stomach and Pyloric Appendages
+  of a Female Salmon, 3⅓ feet long. _a a a_, Pyloric appendages;
+  _ch_, ductus choledochus; _oe_, œsophagus; _st_, lower end
+  of stomach; _p_, pyloric region; _i_, ascending; and _í’_,
+  descending portion of intestine.]
+
+The duodenum receives always the hepatic and pancreatic secretions,
+and, besides, those of the appendices pyloricæ, which, in varying
+numbers (from 1 to 200), are of very common occurrence in Teleosteans
+(Fig. 56). They vary also in length and width, and whilst the
+narrowest serve only as secretory organs, the widest are frequently
+found filled with the same contents as the intestine. When few in
+number, each opens by a separate duct into the duodenum; when their
+number is greater two or more coalesce into a common duct; in the
+latter case the appendages cease to be free, and are connected with one
+another by a more or less firm tissue.
+
+Cœcal appendages at the end of the intestinal tract are of exceedingly
+rare occurrence in fishes (_Box_). There is no _cloaca_ in Teleosteans.
+
+In the majority of Teleosteous fishes the _vent_ is situated on the
+boundary between trunk and tail, behind the ventral fins. In a few it
+lies farther backwards, not far from the caudal fin; more frequently
+it is advanced forwards, under the middle of the abdomen or to the
+scapular arch. In two fishes, _Aphredoderus_ and _Amblyopsis_, it lies
+before the pectoral fins.
+
+A peritoneum envelops all the divisions of the intestinal tract within
+the abdominal cavity. A broad, well-developed _omentum_ has hitherto
+been found in _Gobiesox cephalus_ only.
+
+_Liver_.--The existence of a liver in _Branchiostoma_ as a long
+diverticulum of the intestine has been mentioned above. In the
+Myxinoids the liver is divided into two glandular bodies, an anterior
+rounded smaller one, and a posterior larger one of an elongate shape.
+The gall-bladder lies between both, and receives a cystic duct from
+each of them. In the other fishes the proportionally large liver is a
+single large gland, from which only now and then small portions are
+found to be detached. It is either simple, or with a right and left
+lobe, or with a third lobe in the middle; each lobe may have incisions
+or subdivisions, which, however, are very inconstant. The liver of
+fishes is distinguished by the great quantity of fluid fat (oil) which
+it contains. The gall-bladder is but rarely absent, and attached to
+the right lobe, or towards the centre; however, in some fishes it
+is detached from the liver and connected with it by the cystic duct
+only. The bile may be conveyed by one or more hepatic ducts into a
+common duct which is continued towards the gall-bladder as _ductus
+cysticus_, and towards the duodenum as _ductus choledochus_; or some
+of the hepatic ducts enter directly the gall-bladder, or directly
+the duodenum, without communicating with the common duct. Individual
+variations in this respect are of common occurrence.
+
+A _pancreas_ has been found hitherto in all Chondropterygians,
+Acipenser, and many Teleosteans. In the first it is a glandular mass
+of considerable size behind the stomach, close to the spleen; its duct
+leads into the duodenum. In the Sturgeons the pancreas is attached to
+the duodenum, and opens close to the ductus choledochus. In _Silurus
+glanis_ it is very large, and the ductus choledochus passes through
+its substance; it is smaller in _Belone_ and _Pleuronectes_, and
+situated in the mesentery; its duct accompanies the terminal portion
+of the ductus choledochus. In the Salmon, which possesses a large
+lobed pancreas, the duct is so intimately connected with the ductus
+choledochus that both appear externally as a single duct only.
+
+The _spleen_, which is substantially a lymphatic gland, may be
+mentioned here, as it is constantly situated in the immediate vicinity
+of the stomach, generally near its cardiac portion. With the exception
+of _Branchiostoma_, it is found in all fishes, and appears as a rounded
+or oblong organ of dark-red colour. In the Sharks frequently one or
+more smaller pieces are detached from the principal body. In the Dipnoi
+a thin layer of a very soft substance of brownish-black colour below
+the mucous membrane of the stomach and upper part of the intestine has
+been regarded as the homologue of the spleen (Fig. 57, _m_). In most
+_Teleostei_ the spleen is undivided, and appended by its vessels and
+a fold of the peritoneum to the pyloric bend of the stomach or the
+beginning of the intestine.
+
+  [Illustration: Fig. 57.--Upper part of Intestine of Ceratodus.
+  The anterior wall of the intestine is opened, the liver (_c_) and
+  gall-bladder (_e_) being drawn forward. A slit is made at _n_,
+  through which part of the next compartment of the spirally wound
+  intestine may be seen.
+
+  _é_, Mouth of ductus choledochus; _f_, stomach; _i_, adipose
+  agglomeration; _l_, first compartment of intestinal spire; _m_,
+  spleen; _oe_, lower part of œsophagus, opened; _p_, double
+  pyloric fold; _q_ _q_, glandular patches.]
+
+
+
+
+                              CHAPTER IX.
+
+                        ORGANS OF RESPIRATION.
+
+
+Fishes breathe the air dissolved in water by means of gills or
+branchiæ. The oxygen consumed by them is not that which forms the
+chemical constituent of the water, but that contained in the air which
+is dissolved in water. Hence fishes transferred into water from which
+the air has been driven out by a high temperature, or in which the
+air absorbed by them is not replaced, are speedily suffocated. The
+absorption of oxygen by fishes is comparatively small, and it has been
+calculated that a man consumes 50,000 times more than is required by
+a Tench. However, some fishes evidently require a much larger supply
+of oxygen than others: Eels and Carps, and other fishes of similar
+low vitality, can survive the removal out of their elements for days,
+the small quantity of moisture retained in their gill-cavity being
+sufficient to sustain life, whilst other fishes, especially such as
+have very wide gill-openings, are immediately suffocated after being
+taken out of the water. In some fishes noted for their muscular
+activity, like the _Scombridæ_, the respiratory process is so
+energetic as to raise the temperature of their blood far beyond that
+of the medium in which they live. A few fishes, especially such as
+are periodically compelled to live in water thickened into mud by
+desiccation and vitiated by decomposing substances, breathe atmospheric
+air, and have generally special contrivances for this purpose. These
+are so much habituated to breathing air that many of them, even when
+brought into pure water of normal condition, are obliged to rise
+to the surface at frequent intervals to take in a quantity of air,
+and if they be kept beneath the surface by means of a gauze net,
+they perish from suffocation. The special contrivances consist of
+additional respiratory organs, lodged in cavities either adjoining the
+gill-cavity or communicating with the ventral side of the œsophagus,
+or of the air-bladder which enters upon respiratory functions (Dipnoi,
+Lepidosteus, Amia).
+
+The water used by fishes for respiration is received by the mouth, and
+by an action similar to that of swallowing driven to the gills, and
+expelled by the gill-openings, of which there may be one or several on
+each side behind the head; rarely one only in the median line of the
+ventral surface.
+
+  [Illustration: Fig. 58.--Fore-part of the body of an embryon of
+  Carcharias, showing the branchial filaments (natural size).]
+
+The _gills_ or _branchiæ_ consist essentially of folds of the mucous
+membrane of the gill-cavity (_laminæ branchiales_), in which the
+capillary vessels are distributed. In all fishes the gills are lodged
+in a cavity, but during the embryonic stage the Chondropterygians have
+the gill-laminæ prolonged into long filaments projecting beyond the
+gill-cavity (Fig. 58), and in a few young Ganoids external gills are
+superadded to the internal.
+
+In _Branchiostoma_ the dilated pharynx is perforated by numerous
+clefts, supported by cartilaginous rods (Fig. 29, _h_). The water
+passes between these clefts into the peritoneal cavity, and makes its
+exit by the porus abdominalis situated considerably in advance of the
+vent. The water is propelled by cilia.
+
+In the _Cyclostomes_ the gills of each side are lodged in a series of
+six or more antero-posteriorly compressed sacs, separated from each
+other by intervening septa. Each sac communicates by an inner duct
+with the œsophagus, the water being expelled by an outer duct. In
+_Bdellostoma_ each outer duct has a separate opening, but in _Myxine_
+all the outer ducts pass outwards by one common gill-opening on each
+side. In the Lampreys the ducts are short, the outer ones having
+separate openings (Fig. 2, p. 39). The inner ducts lead into a single
+diverticulum or bronchus, blind behind, situated below the œsophagus,
+and communicating in front with the pharynx, where it is provided with
+two valves by which the regurgitation of the water into the buccal
+cavity is prevented.
+
+The same type of branchial organs persists in _Chondropterygians_,
+which possess five, rarely six or seven, flattened pouches with
+transversely plaited walls. The septa between them are supported by
+cartilaginous filaments rising from the hyoidean and branchial arches.
+Each pouch opens by a cleft outwards, and by an aperture into the
+pharynx, without intervening ducts. The anterior wall of the first
+pouch is supported by the hyoidean arch. Between the posterior wall
+of the first and the anterior of the second sac, and between the
+adjacent walls of the succeeding, a branchial arch with its two series
+of radiating cartilaginous filaments is interposed. Consequently the
+first and last pouch have one set of gill-laminæ only, viz. the first
+on its posterior and the last on its anterior wall. The so-called
+_spiracles_ on the upper surface of the head of Chondropterygians are
+to be referred to in connection with the respiratory organs. They are
+the external openings of a canal leading on each side into the pharynx,
+and situated generally close to and behind the orbit. They frequently
+possess valves or an irregularly indented margin, and are found in all
+species during the embryonic stage, but remaining persistent in a part
+only. The spiracles are the remains of the first visceral cleft of
+the embryo, and in the fœtal state long branchial filaments have been
+observed to protrude, as from the other branchial clefts.
+
+The _Holocephali_ and _Ganoidei_ show numerous deviations from the
+Chondropterygian type, all leading in the direction towards the
+Teleosteans. As a whole they take an intermediate position between the
+preceding types and the Teleosteans, but they show a great variation
+among themselves, and have in common only the imperfect separation
+of the branchial sacs and the presence of a single outer branchial
+aperture.
+
+In _Chimæra_ the septum separating the branchial sacs is confluent
+with the wall of the gill-cavity in a part of its extent only, and
+still more imperfect is the separation of those branchial divisions
+in _Ceratodus_ (Fig. 60). The other Ganoids show no such division
+whatever. In _Chimæra_ the first gill is incomplete (uniserial), and
+belongs to the hyoid; then follow three complete gills; the last,
+belonging to the fourth branchial arch, being again incomplete.
+_Acipenser_, _Scaphirhynchus_, _Lepidosiren_, _Protopterus_,
+and _Lepidosteus_, possess likewise an anterior incomplete gill
+(_opercular gill_), followed by four complete gills in the Sturgeons
+and _Lepidosteus_, whilst in _Lepidosiren_ and _Protopterus_ a part
+of the branchial arches is gill-less. In _Polyodon_, _Ceratodus_, and
+_Polypterus_, an opercular gill is absent, the two former having four
+complete gills, the latter three and a half only. _Spiracles_ are still
+in some Ganoids present, viz. in the Sturgeons and _Polypterus_. In all
+the Ganoids an osseous gill-cover is now developed.
+
+In the _Teleostei_ the gills with their supporting branchial arches
+lie in one undivided cavity; more or less wide clefts between the
+arches lead from the pharynx to the gills, and a more or less wide
+opening gives exit to the water after it has washed the gills. The
+interbranchial clefts have sometimes nearly the same extent as the
+branchial arches; sometimes they are reduced to small openings, the
+integuments stretching from one arch to the other. Sometimes there
+is no cleft behind the fourth arch, in which case this arch has only
+an uniserial gill developed. The gill-opening likewise varies much
+in its extent, and when reduced to a foramen may be situated at any
+place of the posterior boundary of the head. In the _Symbranchidæ_
+the gill-openings coalesce into a single narrow slit in the median
+line of the isthmus. In the majority of Teleosteans the integument of
+the concave side of the branchial arches develops a series of horny
+protuberances of various form, the so-called _gill-rakers_. They are
+destined to catch any solid corpuscles or substances which would be
+carried into the gill-cavity with the water. In some fishes they are
+setiform, and form a complete sieve, whilst in others they are merely
+rough tubercles, the action of which must be very incomplete if they
+have any function at all.
+
+Most Teleosteans possess four complete gills, but frequently the
+fourth arch is provided with an uniserial gill only, as mentioned
+above, or even entirely gill-less. The most imperfect gills are found
+in _Malthe_, which has two and a half gills only, and in _Amphipnous
+cuchia_, in which one small gill is fixed to the second arch.
+
+The gills of the Teleosteans as well as of the Ganoids are supported by
+a series of solid cartilaginous or horny pointed rods, arranged along
+the convex edges of the branchial arches. Arches bearing a complete
+gill have two series of those rods, one along each edge; those with
+uniserial gills bear one row of rods only. The rods are not part
+of the arch, but fixed in its integument, the several rods of one
+row corresponding to those of the other, forming pairs (_feuillet_,
+Cuvier) (Fig. 59). Each rod is covered by a loose mucous membrane
+passing from one rod to its fellow opposite, which again is finely
+transversely plaited, the general surface being greatly increased by
+these plaits. In most Teleostei the branchial lamellæ are compressed,
+and taper towards their free end, but in the Lophobranchs their base
+is attenuated and the end enlarged. The mucous membrane contains the
+finest terminations of the vessels, which, being very superficial,
+impart the blood-red colour to living gills. The _Arteria branchialis_,
+the course of which lies in the open canal in the convexity of the
+branchial arch, emits a branch (_a_) for every pair of lamellæ which
+ascends (_b_) along the inner edge of the lamella, and supplies every
+one of the transverse plaits with a branchlet. The latter break up into
+a fine net of capillaries, from which the oxygenised blood is collected
+into venous branchlets, returning by the venous branch (_d_), which
+occupies the outer edge of the lamella.
+
+  [Illustration:
+
+   Fig. 59.--A pair of branchial lamellæ (magnified) of the Perch.
+
+    _a_, Branch of Arteria branchialis; _b_, Ascending branch of
+    the same; _c_, Branch of Vena branchialis; _d_, Descending
+    branch of the same; _e_, Transverse section through the
+    branchial arch.]
+
+The so-called _Pseudobranchiæ_ (Fig. 60) are the remains of an anterior
+gill which had respiratory functions during the embryonic life of the
+individuals. By a change in the circulatory system these organs have
+lost those functions, and appear in the adult fish as retia mirabilia,
+as they receive oxygenised blood, which, after having passed through
+their capillary system, is carried to other parts of the head. In
+Palæichthyes the pseudobranchia is a rete mirabile caroticum for the
+brain and eye; in Teleosteans a rete mirabile ophthalmicum only.
+Pseudobranchiæ are as frequently absent as present in Chondropterygians
+as well as Teleosteans. As to the Ganoids, they occur in _Ceratodus_,
+_Acipenser_, _Polyodon_, and _Lepidosteus_, and are absent in
+_Lepidosiren_, _Protopterus_, _Scaphirhynchus_, _Polypterus_, and
+_Amia_.
+
+In Chondropterygians and Sturgeons the pseudobranchiæ are situated
+within the spiracles; in those, in which spiracles have become
+obliterated, the pseudobranchiæ lie on the suspensorium, hidden below
+cellular tissue; but pseudobranchiæ are not necessarily co-existent
+with spiracles. In the other Ganoids and Teleosteans the pseudobranchiæ
+(Fig. 60, _h_) are within the gill-cavity, near the base of the
+gill-cover; in _Ceratodus_ even rudiments of the gill-rakers (_x’_,
+_x”_) belonging to this embryonic gill are preserved, part of them
+(_x”_) being attached to the hyoid arch. Pseudobranchiæ are frequently
+hidden below the integuments of the gill-cavity, and have the
+appearance of a glandular body rather than of a gill.
+
+   [See Müller, “Vergleichende Anatomie des Gefäss-systems der
+   Myxinoiden;” and “Ueber den Bau und die Grenzen der Ganoiden.”]
+
+  [Illustration: Fig. 60.--Gills of Ceratodus.
+
+    _x_, Arcus aortæ; _gl_, Glossohyal; _ch_, Ceratohyal; _u_,
+    Attachment of the first gill to the walls of the gill-cavity;
+    _h_, Pseudobranchia; _x’_, _x”_, two series of gill-rakers
+    belonging to the Pseudobranchia.]
+
+_Accessory respiratory organs_ for retaining water or breathing air,
+such as are found in the _Labyrinthici_, _Ophiocephalidæ_, certain
+_Siluridæ_, and _Lutodira_, are structures so specialised that they are
+better described in the accounts of the Fishes in which they have been
+observed.
+
+       *       *       *       *       *
+
+_Air-Bladder._--The air-bladder, one of the most characteristic organs
+of fishes, is a hollow sac, formed of several tunics, containing gas,
+situated in the abdominal cavity, but without the peritoneal sac,
+entirely closed or communicating by a duct with the intestinal tract.
+Being compressible, its special functions consist in altering the
+specific gravity of the fish or in changing the centre of gravity. In a
+few fishes it assumes the function of the organ of higher Vertebrates,
+of which it is the homologue--viz. of a _lung_.
+
+The gas contained in the air-bladder is secreted from its inner
+surface. In most freshwater fishes it consists of nitrogen, with a very
+small quantity of oxygen and a trace of carbonic acid; in sea-fishes,
+especially those living at some depth, oxygen predominates, as much
+as 87 per cent having been found. Davy found in the air-bladder of a
+fresh-run Salmon a trace of carbonic acid and 10 per cent of oxygen,
+the remainder of the gas being nitrogen.
+
+An air-bladder is absent in _Leptocardii_, _Cyclostomi_,
+_Chondropterygii_, and _Holocephali_; but occurs in all Ganoids, in
+which, besides, its respiratory functions more or less clearly manifest
+themselves. Its occurrence in Teleosteans is most irregular, closely
+allied species sometimes differing from each other in this respect; it
+shows in this sub-class the most extraordinary modifications, but has
+no respiratory function whatever.
+
+Constantly situated within the abdominal cavity, below the vertebral
+column, but without the sac of the peritoneum which covers only its
+ventral portion, the air-bladder is frequently prolonged into the
+tail, the prolongation being either simple and lodged between the
+non-united parapophyses, or double and penetrating between the muscles
+and hæmapophyses of each side. In the opposite direction processes of
+the air-bladder may penetrate into the skull, as has been mentioned
+above (p. 117). In some fishes the air-bladder is almost loose in the
+abdominal cavity, whilst in others it adheres most intimately by firm
+and short tissue to the vertebral column, the walls of the abdomen, and
+the intestines. In the Cobitina and many Siluroids it is more or less
+completely enclosed in osseous capsules formed by the vertebræ.
+
+The tunics of the majority of air-bladders are an extremely fine
+internal one, frequently shining silvery, containing crystalline
+corpuscles, sometimes covered with a pavement-epithelium; and a thicker
+outer one of a fibrous texture, which sometimes attains to considerable
+thickness and yields isinglass. This wall is strengthened in many
+fishes by muscular layers for the compression of the whole organ or of
+some portion of it.
+
+A distinction has been made between air-bladders which communicate by
+a duct with the intestinal tract and those which are entirely closed.
+However, it is to be remembered that at an early stage of development
+all air-bladders are provided with such a duct, which in a part of the
+fishes more or less completely obliterates, being then represented by
+a fine ligament only. In young _Lucioperca_ of six to eight inches in
+length the duct may be found still open for a considerable distance;
+and, on the other hand, in adult _Physostomi_, that is Teleosteous
+fishes with a ductus pneumaticus, not rarely the whole duct is found
+very narrow, or, for some part of its length, even entirely closed.
+
+  [Illustration: Fig. 61.--Air-bladder of Otolithus sp.]
+
+  [Illustration:
+
+    Fig. 62.--Vertical section through abdominal cavity of
+    Collichthys lucida. _b_, air-bladder; _l_, liver; _s_,
+    stomach; _epp_ and _ipp_, external and internal laminæ of
+    peritoneum parietale; _epv_ and _ipv_, external and internal
+    laminæ of peritoneum viscerale; _dv_, dorsal air-vessels;
+    _vv_, ventral air-vessels.]
+
+Air-bladders without duct are found in Acanthopterygians,
+Pharyngognaths, Anacanths, and Lophobranchs. They may consist of
+a single cavity or divided by constrictions into two or three
+partitions situated behind one another; they may consist of two lateral
+partitions, assuming a horseshoe-like form, or they may be a single
+sac with a pair of simple or bifid processes in front or behind (Fig.
+61). The families of _Sciænidæ_ and _Polynemidæ_ possess air-bladders
+with a most extraordinary development of appendages rising from each
+side of the air-bladder. In the Sciænoid (Fig. 63) fifty-two branches
+issue from each side, each branch being bifurcate and bearing smaller
+appendages. In _Pogonias chromis_ (Fig. 64) the sides of the anterior
+half is provided with irregular broad-fringed appendages, the hindmost
+of which communicates by a narrow duct with the posterior extremity
+of the air-bladder. In _Collichthys lucida_ (Fig. 62) twenty-five
+appendages issue from each side; the anterior ones are directed towards
+the front, but the lateral assume a more posterior direction, the
+nearer they are to the posterior extremity of the air-bladder, where
+they form an assemblage giving the appearance of a cauda equina. All
+these appendages soon bifurcate in a dorsal and ventral stem; these
+stems bifurcate again and again, and either terminate after the first
+or second bifurcation or are so far prolonged as to reach the median
+line of the ventral and dorsal sides, anastomosing with the branches
+of the other side. The branches being enveloped in laminæ of the
+peritonæum, form a dorsal and ventral sac of beautiful appearance,
+caused by the regular arrangement of the air-vessels. The dorsal sac is
+situated between the air-bladder and the roof of the abdominal cavity
+without being attached to the latter. The ventral sac receives within
+its cavity the intestine, liver, and ovaries.--A peculiar mechanism
+has been observed in the air-bladder of the _Ophidiidæ_, the anterior
+portion of which can be prolonged by the contraction of two muscles
+attached to its anterior extremity, with or without the addition of a
+small bone.
+
+  [Illustration: Fig. 63.--Air-bladder of a Sciænoid.
+
+   I. Visceral surface opened at _b_, to show openings of the
+   lateral branches.
+
+   II. Isolated lateral branch; _a_, its opening into the
+   cavity of the air-bladder.]
+
+Air-bladders with a pneumatic duct are found in Ganoids and
+Physostomes, the duct entering the dorsal side of the intestinal
+tract, with the exception of _Polyp__terus_ and the _Dipnoi_, in
+which it enters on the ventral side of the œsophagus. In the majority
+the orifice is in the œsophagus, but in some, as in _Acipenser_, in
+the cardiac portion of the stomach, or in its blind sac, as in many
+Clupeoids. The air-bladder may be single, or consist of two divisions
+situated one behind the other (Fig. 52); its inner surface may be
+perfectly smooth, or form manifold pouches and cells. If two divisions
+are present the anterior possesses a middle elastic membrane which
+is absent in the posterior; each division has a muscular layer, by
+which it can be separately compressed, so that part of the contents of
+the posterior may be driven into the elastic anterior division, and
+_vice versa_. The posterior division being provided with the ductus
+pneumaticus does not require the elasticity of the anterior.
+
+  [Illustration: Fig. 64.--Air-bladder of Pogonias chromis.]
+
+Some Siluroids possess a peculiar apparatus for voluntarily exercising
+a pressure upon the air-bladder. From the first vertebra a process
+takes its origin on each side, expanding at its end into a large round
+plate; this is applied to the side of the air-bladder, and by pressing
+upon it expels the air through the duct; the small muscle moving the
+plate rises from the skull.
+
+The connection of the air-bladder with the organ of hearing in some
+Physostomes has been described above, p. 117.
+
+In the modifications of the air-bladder, hitherto mentioned, the
+chief and most general function is a mechanical one; this organ
+serves to regulate the specific gravity of the fish, to aid it in
+maintaining a particular level in the water, in rising or sinking,
+in raising or depressing the front part of its body as occasion may
+serve. Yet a secretion of gas from the blood into its cavity must take
+place; and if this be so, it is not at all impossible that also an
+exchange of gases between the two kinds of blood is effected by means
+of the extraordinary development of _retia mirabilia_ in many
+air-bladders.
+
+In all fishes the arteries of the air-bladder take their origin from
+the aorta or the system of the aorta, and its veins return either to
+the portal, or vertebral, or hepatic veins; like the other organs of
+the abdominal cavity it receives arterial blood and returns venous
+blood. However, in many fishes the arteries as well as veins break
+up below the inner membrane into _retia mirabilia_ in various ways.
+The terminal ramifications of the arteries may dissolve into fan-like
+tufts of capillaries over almost every part of the inner surface,
+as in Cyprinoids. Or these tufts of radiating capillaries are more
+localised at various places, as in _Esocidæ_; or the tufts are so
+aggregated as to form gland-like, _red bodies_, the capillaries
+reuniting into larger vessels, which again ramify freely round the
+border of the red body; the red bodies are formed not only by minute
+arteries but also by minute veins, both freely anastomosing with
+its kind, and being inextricably interwoven. The rest of the inner
+surface of the air-bladder receives its blood, not from the red bodies,
+but from normally ramifying vessels. This kind of rete mirabile or
+“vaso-ganglion” is found in the Perch and Gadoids; it is generally
+distributed in closed air-bladders, but also sometimes observed in
+air-bladders’ with pneumatic duct. In _Anguilla_ and _Conger_ two
+similar vaso-ganglia are situated at the sides of the opening of the
+pneumatic duct.
+
+  [Illustration: Fig. 65.--Lung of Ceratodus opened in its lower
+  half to show its cellular pouches. _a_, Right half; _b_, Left
+  half; _c_, Cellular pouches; _e_, Vena pulmonalis; _f_, Arterial
+  blood-vessel; _oe_, Œsophagus opened, to show glottis (_gl._)]
+
+Whilst the air-bladders of some _Ganoids_, anatomically as well as
+functionally, closely adhere to the Teleosteous type, that of _Amia_
+is more cellular and lung-like in its interior than the Teleosteous
+air-bladder, and _Polypterus_ approaches the Dipnoi not only in
+having a laterally divided air-bladder but also in its pneumatic duct
+entering the _ventral_ side of the œsophagus. The air-bladder of the
+_Dipnoi_ possesses still more the anatomical characteristics of a lung
+and assumes its functions, though, as it co-exists with gills, only
+periodically or in an auxiliary manner. The ductus pneumaticus is a
+membranous bronchus, entering the ventral side of the œsophagus, and
+provided at its entrance with a _glottis_. In _Ceratodus_ (Fig. 65) the
+lung is still a single cavity, but with a symmetrical arrangement of
+its internal pouches; it has no pulmonal artery, but receives branches
+from the _arteria cœliaca_. Finally, in _Lepidosiren_ and _Protopterus_
+the lung is completely divided into lateral halves, and by its cellular
+structure approaches most nearly that of a reptile; it is supplied with
+venous blood by a true pulmonary artery.
+
+  [Illustration: Fig. 66.--Heart of Lepidosteus osseus.
+
+  I. External aspect. II. Conus arteriosus opened.
+
+    _a_, Atrium; _b_, Conus arteriosus; _v_, Ventricle; _h_,
+    Branchial artery for 3d and 4th gill; _k_, for the second;
+    _l_, for the first; _m_, branch for the opercular gill; _d_,
+    Single valve at the base of the conus; _e-g_, Transverse rows
+    of Ganoid valves.]
+
+
+
+
+                              CHAPTER X.
+
+                        ORGANS OF CIRCULATION.
+
+
+The _Blood-corpuscles_ of fishes are, with one exception, of an
+elliptic shape; this exception is _Petromyzon_, which possesses
+circular, flat, or slightly biconvex blood-corpuscles. They vary much
+in size; they are smallest in Teleosteans and Cyclostomes, those of
+_Acerina cernua_ measuring 1/2461 of an inch in their longitudinal, and
+1/3000 in their transverse diameter. As far as it is known at present
+the _Salmonidæ_ have the largest blood-corpuscles among Teleosteans,
+those of the salmon measuring 1/1524 by 1/2460 in., approaching those
+of the Sturgeon. Those of the Chondropterygians are still larger; and
+finally, _Lepidosiren_ has blood-corpuscles not much smaller than those
+of Perennibranchiates, viz.--1/570 by 1/941 in. Branchiostoma is the
+only fish which does not possess red blood-corpuscles.
+
+   [See G. Gulliver, “Proc. Zool. Soc.,” 1862, p. 91; and 1870, p.
+   844; and 1872, p. 833.]
+
+Fishes, in common with the other Vertebrates, are provided with a
+complete circulation for the body, with another equally complete for
+the organs of respiration, and with a particular abdominal circulation,
+terminating at the liver by means of the _vena portæ_; but their
+peculiar character consists in this, that the branchial circulation
+alone is provided at its base with a muscular apparatus or _heart_,
+corresponding to the right half of the heart of Mammalia and Birds.
+
+The _Heart_ is situated between the branchial and abdominal cavities,
+between the two halves of the scapulary arch, rarely farther behind,
+as in _Symbranchidæ_. It is enclosed in a _pericardium_, generally
+entirely separated from the abdominal cavity by a diaphragma, which
+is, in fact, the anterior portion of the peritoneum, strengthened
+by aponeurotic fibres. However, in some fishes there is a
+communication between the pericardial and peritoneal sacs, viz. in
+the Chondropterygians and Acipenser, whilst in the Myxinoids the
+pericardial sac is merely a continuation of the peritoneum.
+
+  [Illustration: Fig. 67.--Heart of Ceratodus.
+
+    _a_, Atrium; _b_, Conus arteriosus; _d_, Papillary valve
+    within the conus; _e-g_, Transverse rows of Ganoid valves;
+    _h_, _i_, Anterior arcus aortæ; _k_, _l_, Posterior arcus
+    aortæ; _v_, Ventricle.]
+
+The heart is, relatively to the size of the body, very small, and
+consists of three divisions: the _atrium_, with a large _sinus
+venosus_ into which the veins enter; the _ventricle_; and a conical
+hollow swelling at the beginning of the arterial system, the structure
+of which forms one of the most important characters used in the
+classification of fishes. In all _Palæichthyes_ (Figs. 66 and 67) this
+swelling is still a division of the pulsating heart, being provided
+with a thick muscular stratum; it is not separated from the ventricle
+by two valves opposite to each other, but its interior is fitted with
+a plurality of valves, arranged in transverse series more or less
+numerous in the various groups of _Palæichthyes_. _Lepidosiren_ and
+_Protopterus_ offer an example of a modification of this valvular
+arrangement, their valves being longitudinal, each valve in fact being
+formed by the confluence of several smaller ones situated behind one
+another. This Palæichthyan type is called _conus arteriosus_.
+
+In Cyclostomes and Teleosteans (Fig. 68) the enlargement is a swelling
+of the artery, without muscular stratum and without contractility; with
+the exception of the Myxinoids its walls are thick, fibrous, with many
+trabeculæ and pouches, but it has no valves in its interior, and is
+separated from the ventricle by two valves opposite to each other. This
+Teleostean type is called _bulbus aortæ_.
+
+  [Illustration: Fig. 68.--Bulbus aortæ of Xiphias gladius, opened.
+
+    _a_, Section through part of the wall of ventricle; _b_,
+    Section through the bulbus; _c_, Teleosteous valves of the
+    ostium arteriosum; _d_, Accessory valves, of rudimentary
+    nature and inconstant; _e_, Trabeculæ carneæ of the bulbus.]
+
+The sinus venosus sends the whole of the venous blood by a single
+orifice of its anterior convexity into the atrium; two thin membranous
+valvules turned towards the atrium, prevent the blood from re-entering
+the sinus. A pair of other valves between atrium and ventricle have the
+same function. The walls of the ventricle are robust, and, internally,
+it is furnished with powerful fleshy trabeculæ.
+
+The bulbus or conus arteriosus is prolonged into the branchial artery
+which soon divides, sending off a branch to each branchial arch. On
+returning from the respiratory organ the branchial veins assume the
+structure and functions of arteries. Several branches are sent off
+to different portions of the head and to the heart, but the main
+trunks unite to form the great artery which carries the blood to the
+viscera and all the parts of the trunk and tail, and which, therefore,
+represents the _aorta_ of higher animals.
+
+In the majority of Teleosteans the _aorta_ has proper walls formed
+by its own membranes, but in the Sturgeons it is independent at its
+commencement only, and replaced by a canal formed by hæmal elements of
+the vertebral column, and clothed inside with a perichondrium. In many
+Chondropterygians and some Teleosteans (_Esox_, _Clupea_, _Silurus_),
+the aorta possesses its own firm membranes along its ventral side,
+dorsally being protected by a very thin membrane only, attached to the
+concavity of the centra of the vertebræ.
+
+The circulatory system of _Branchiostoma_ and of the _Dipnoi_ shows
+essential differences from that of other fishes.
+
+_Branchiostoma_ is the only fish which does not possess a muscular
+heart, several cardinal portions of its vascular system being
+contractile. A great vein extends forwards along the caudal region
+below the notochord, and exhibits contractility in a forward direction;
+it is bent anteriorly, passing into another tube-like pulsatile trunk,
+the branchial heart, which runs along the middle of the base of the
+pharynx, sending off branches on each side to the branchiæ; each of
+these branches has a small contractile dilatation (_bulbillus_) at
+its base. The two anterior branches pass directly into the aorta, the
+others are branchial arteries, the blood of which returns by branchial
+veins emptying into the aorta. The blood of the intestinal veins is
+collected in a contractile tube, the portal vein, situated below the
+intestine, and distributed over the rudimentary liver. Of all other
+fishes, only in _Myxinoids_ the portal vein is contractile. All the
+blood-corpuscles of _Branchiostoma_ are colourless and without nucleus.
+
+In _Dipnoi_ a rudimentary division of the heart into a right and
+left partition has been observed; this is limited to the ventricle
+in _Ceratodus_, but in _Lepidosiren_ and _Protopterus_ an incomplete
+septum has been observed in the atrium also. All Dipnoi have a pulmonal
+vein, which enters the atrium by a separate opening, provided with a
+valve. The pulmonal artery rises in _Lepidosiren_ and _Protopterus_
+from an arch of the aorta, but in _Ceratodus_ it is merely a
+subordinate branch, rising from the _Arteria cœliaca_.
+
+
+
+
+                              CHAPTER XI.
+
+                            URINARY ORGANS.
+
+
+In _Branchiostoma_ no urinary organs have been found.
+
+In Myxinoids these organs are of a very primitive structure: they
+consist of a pair of ducts, extending from the urogenital porus through
+the abdominal cavity. Each duct sends off at regular intervals from
+its outer side a short wide branch (the uriniferous tube), which
+communicates by a narrow opening with a blind sac. At the bottom of
+this sac there is a small vaso-ganglion (_Malpighian corpuscle_),
+by which the urine is secreted.
+
+In the Lampreys the kidneys form a continuous gland-like body, with
+irregular detached small portions. The ureters coalesce before they
+terminate in the urogenital papilla.
+
+In Chondropterygians the kidneys occupy the posterior half or
+two-thirds of the back of the abdominal cavity, without the sac of the
+peritoneum (as in all fishes) which forms a firm tendinous horizontal
+septum. The kidneys of the two sides are never confluent, and generally
+show a convoluted or lobulated surface. The ureters are short; each is
+dilated into a pouch, and communicating with its fellow terminates by a
+single urethra (which also receives the vasa deferentia) behind the end
+of the rectum in the large common cloaca.
+
+In Ganoids the kidneys occupy a similar position as in
+Chondropterygians, but these fishes differ considerably with regard
+to the termination and the arrangement of the ends of the urogenital
+ducts. The Dipnoi possess a cloaca. In _Ceratodus_ the ureters
+open into it by a common opening, separate from the genital opening;
+and no closed urinary bladder has been developed. _Lepidosiren_
+has a small urinary bladder; the ureters do not communicate directly
+with it, but terminate separately on small papillæ in the dorsal
+compartment of the cloaca. The other Ganoids lack a cloaca, and the
+urogenital opening is behind the vent as in Teleosteans. In all the
+genital and urinary ducts coalesce towards their end. The Sturgeons
+have no urinary bladder, whilst it is present in _Amia_, the
+ureters opening separately into it.
+
+The _kidneys_ of Teleosteans are situated likewise without the
+peritoneal cavity, immediately below some part of the vertebral column,
+and vary exceedingly with regard to form and extent. Sometimes they
+reach from the skull to between the muscles of the tail, sometimes
+they are limited to the foremost part of the abdominal cavity (in
+advance of the diaphragm), but generally their extent corresponds to
+that of the abdominal portion of the vertebral column. Frequently
+they are irregular on their dorsal surface, filling every available
+recess, flat, attenuated on the sides, more or less coalescent towards
+the middle; in other fishes they are more compact bodies. The ureters
+terminate, either separate or united, in a urinary bladder, varying
+in shape, which opens by a short urethra behind the vent. The urinary
+opening may be separate or confluent with that of the genital ducts,
+and is frequently placed on a more or less prominent papilla (_papilla
+urogenitalis_). If separate, the urinary opening is behind the genital;
+and if a papilla is developed, its extremity is perforated by the
+urethra, the genital opening being situated nearer the base. A few
+Teleosteans show an arrangement similar to that of Chondropterygians
+and Dipnoi, the urogenital openings being in the posterior wall of the
+rectum (_Symbranchidæ_, _Pediculati_, and some _Plectognathi_).
+
+
+
+
+                             CHAPTER XII.
+
+                        ORGANS OF REPRODUCTION.
+
+
+All fishes are _dioecious_, or of distinct sex. Instances of so-called
+_hermaphroditism_ are, with the exception of _Serranus_, abnormal
+individual peculiarities, and have been observed in the Cod-fish, some
+Pleuronectidæ, and in the Herring. Either the generative organ of one
+side was found to be male, that of the other female; or the organ of
+one or both sides was observed to have been developed partly into an
+ovary partly into a testicle. In the European species of Serranus a
+testicle-like body is attached to the lower part of the ovary; but
+many specimens of this genus are undoubtedly males, having normally
+developed testicles only.
+
+The majority of fishes are oviparous, comparatively few viviparous;
+the embryos being developed either in the ovarium or in some dilated
+portion of the oviduct. In viviparous fishes actual copulation takes
+place, and the males of most of them are provided with copulatory
+or intromittent organs. In oviparous fishes the generative products
+are, during sexual excitement, discharged into the water, a very
+small quantity of semen being sufficient for effectual impregnation
+of a number of ova dispersed in a considerable quantity of water;
+circumstances which render _artificial impregnation_ more practicable
+than in any other class of animals.
+
+In _Branchiostoma_ the generative organs occupy the ventral side of the
+abdominal cavity, into which they discharge their contents. No ducts
+are developed in either sex.
+
+In the _Cyclostomes_ the generative organ is single, and fixed to or
+suspended from the median line of the back of the visceral cavity
+by a duplicature of the peritoneum (_mesoarium_); the testicle and
+ovary being distinguishable by their contents only. These escape by
+dehiscence of the cells or capsules and rupture of the peritoneal
+covering into the abdominal cavity, and are expelled by reciprocal
+pressure of the intertwined sexes through the _porus genitalis_, which
+is sunk between two labia of the skin in _Myxine_, and produced into a
+long papilla in Petromyzon.
+
+  [Illustration: Fig. 69.--Ovum of Myxine glutinosa, enlarged.]
+
+The ova of the Lampreys are small, globular, like those of Teleosteans.
+Those of Myxine have a very peculiar shape when mature; they are of an
+oval form, about 15 millimetres long and 8 millimetres broad, enveloped
+in a horny case, which at each end is provided with a bundle of short
+threads, each thread ending in a triple hook. Whilst in the mesoarial
+fold the eggs are attached to one another by means of these hooks, and
+after being expelled they probably fix themselves by the same means to
+other objects. As in all fishes producing ova of large size, the number
+of ova matured in one season is but small.
+
+In _Teleosteans_ the generative organs are comparatively large. In
+some families the ovaries are without closed covering and without
+oviducts, as in _Salmonidæ_, _Galaxiidæ_, _Notopteridæ_, _Murænidæ_,
+and others. The surface of such an open ovary--as, for instance, that
+of the Salmon--is transversely plaited, the ova being developed in
+capsules in the stroma of the laminæ; after rupture of the capsules
+the mature ova drop into the abdominal cavity, and are expelled by
+the porus genitalis. The ovaries of the other Teleosteans are closed
+sacs, continued into oviducts. Frequently such ovaries coalesce into a
+single body, or one in which the division is effected internally only
+by a more or less complete septum. Fixed by a mesoarium, the ovaries
+occupy generally a position outwards of the intestine or air-bladder;
+their form varies as well as the thickness and firmness of their
+covering, which frequently is an extremely thin transparent membrane.
+The inner surface of the ovarian sac is transversely or longitudinally
+plaited or covered with fringes, on which the ova are developed, as
+in the open ovaries. In the viviparous Teleosteans the embryons are
+likewise developed within the ovary, notably in the _Embiotocidæ_, many
+_Blenniidæ_, and _Cyprinodontidæ_, _Sebastes viviparus_, etc. Among the
+Cyprinodonts the end of the oviduct is attached to the anterior anal
+rays, which are modified into supports of its termination. In _Rhodeus_
+the oviduct is periodically prolonged into a long oviferous tube, by
+means of which the female deposits her ova into the shells of living
+Bivalves.
+
+  [Illustration: Fig. 70.--Ditrema argenteum, with fully developed
+  young, ready for expulsion by the genital orifice, _o_;
+  _a_, folds of the ovarian sac; _v_, vent.]
+
+The _ova_ of Teleosteous Fishes are extremely variable in size, quite
+independently of the size of the parent species. The ova of large and
+small individuals of the same species, of course, do not differ in
+size; but, on the whole larger individuals produce a greater number
+of ova than smaller ones of the same species. The larger the size of
+the ova is in a species, the smaller is the number produced during
+one season. The ova of the Eel are almost microscopic. The small
+sized roe in the Herring, Lump-fish, Halibut, and Cod-fish, have been
+estimated at respectively 25,000, 155,000, 3,500,000, and 9,344,000.
+Larger in size and fewer in number are those of _Antennarius_, _Salmo_,
+_Aspredo_, _Lophobranchs_, etc. Comparatively largest are those of
+_Gastrosteus_; and the Siluroid genus _Arius_, the males of which
+take care of their progeny, produces ova from 5 to 10 millimeters
+in diameter. The ova of all Teleosteans are perfectly globular and
+soft-shelled. Teleosteans without oviduct, deposit them separated from
+one another; whilst in many Teleosteans with an oviduct the ova are
+enveloped in a glutinous substance, secreted by its glands, swelling in
+the water and forming lumps or cords, in which the ova are aggregated.
+
+  [Illustration: Fig. 71. Ovum of Arius boakii (Ceylon), showing
+  embryo. Nat. size.]
+
+  [Illustration: Fig. 72.--Abdomen of _Aspredo batrachus_,
+  with the ova attached; at _a_, the ova are removed, to show
+  the spongy structure of the skin, and the processes filling the
+  interspaces between the ova. (Natural size.)]
+
+Instances of the female taking care of her progeny are extremely scarce
+in fishes. At present only two examples are known, that of the Siluroid
+genus _Aspredo_, and of _Solenostoma_. In the former, during the time
+of propagation, the integuments of the lower side of the flat trunk of
+the female assume a soft and spongy texture. After having deposited
+the eggs, the female attaches them to, and presses them into, the
+spongy integument, by merely lying over them. She carries them on her
+belly, as the Surinam Toad (_Pipa_) carries her ova on the back. When
+the eggs are hatched the excrescence on the skin disappears, and the
+abdomen becomes as smooth as before. In _Solenostoma_ the inner side
+of the long and broad ventral fins coalesces with the integuments of
+the body, a large pouch being formed for the reception of the eggs.
+There is a peculiar provision for the retention of the eggs in the
+sac, and probably for the attachment of the embryo. The inner walls of
+the sac are lined with long filaments, arranged in series along the
+ventral rays, and more numerous and longer at the base of the rays than
+in the middle of their length, behind which they disappear entirely.
+They are also more developed in examples in which eggs are deposited
+in the sac than in those which have the sac empty. The filaments most
+developed have a length of half an inch, and are beset with mamilliform
+appendages. A slightly undulated canal runs along the interior of the
+filament.
+
+  [Illustration: Fig. 73.--Solenostoma cyanopterum ♂ (Indian
+  Ocean).]
+
+  [Illustration: Fig. 74.--Pouch with ova, formed by the ventral
+  fins of _Solenostoma_. Lower aspect; the edges of the fins
+  have been pushed aside to allow of a view of the inside of the
+  pouch. (Natural size.)]
+
+The _Testicles_ of the _Teleosteans_ are always paired, and occupy the
+same position as the ovaries. Their size varies extraordinarily at the
+different seasons of the year. Vasa deferentia are constant. In the
+males of viviparous Teleosteans the urogenital papilla is frequently
+enlarged, and clearly serves as an intromittent organ. In _Clinus
+despicillatus_ the vas deferens widens within the abdomen into a cavity
+occupied by a complex network of loose fasciculi, rising from the
+mucous membrane. The cavity can be compressed by a special powerful
+muscle, the accumulated semen being thus expelled with considerable
+force through the narrow aperture of the penis. In many Cyprinodonts
+the vas deferens runs along the anterior anal rays, which may be
+thickened, and prolonged into a long slender organ.
+
+Many Teleostei take care of their progeny, but with the exception of
+_Aspredo_ and _Solenostoma_, mentioned above (p. 160), it is the male
+on which this duty devolves. In some, as in _Cottus_, _Gastrosteus_,
+_Cyclopterus_, _Antennarius_, _Ophiocephalus_, _Callichthys_, the male
+constructs with more or less skill a nest, and jealously guards the
+ova deposited in it by the female. The male of some species of _Arius_
+carries the ova (Fig. 71) about with him in his capacious pharynx.
+The species of _Chromis_, inhabiting the sea of Galilee, are said
+to take care of their ova in the same manner. And, finally, in the
+Lophobranchs, nature has aided this instinct by the development of a
+pouch on the abdomen or lower side of the tail. In the Syngnathidæ this
+pouch is formed by a fold of the skin developed from each side of the
+trunk and tail, the free margins of the fold being firmly united in the
+median line, whilst the eggs are being hatched in the inside of the
+pouch. In _Hippocampus_ the pouch is completely closed, with a narrow
+anterior opening.
+
+  [Illustration: Fig. 75.--Syngnathus acus ♂, with
+  sub-caudal pouch.]
+
+  [Illustration: Fig. 76.--Sub-caudal pouch of Syngnathus acus,
+  with the young, ready to leave the pouch. One side of the
+  membrane of the pouch is pushed aside to admit of a view of its
+  interior. (Natural size.)]
+
+The genital organs of _Ganoids_ show similar diversity of structure as
+those of Teleosteans, but on the whole they approach the Batrachian
+type. The ovaries are not closed, except in _Lepidosiren_; all
+Ganoids possess oviducts. In the Sturgeons the oviduct as well as the
+vas deferens is represented by a funnel-shaped prolongation of the
+peritoneum, which communicates with the wide ureter. The inner aperture
+of the funnel is on a level of the middle of the testicle or ovary,
+the outer within the ureter; and it is a noteworthy fact that only at
+certain periods of the life of the fish this outer aperture is found
+to be open,--at other times the peritoneal funnel appears as a closed
+blind sac within the ureter. The mode of passage of the semen into the
+funnel is not known.
+
+In _Polypterus_ and _Amia_, proper oviducts, with abdominal apertures
+in about the middle of the abdominal cavity, are developed; they
+coalesce with the ureters close to the common urogenital aperture.
+
+In _Ceratodus_ (Fig. 77), a long convoluted oviduct extends to the
+foremost limit of the abdominal cavity, where it opens by a slit at
+a considerable distance from the front end of the long ovary; this
+aperture is closed in sexually immature specimens. The oviducts unite
+close to their common opening in the cloaca. During their passage
+through the oviduct the ova receive a gelatinous covering secreted by
+its mucous membrane. This is probably also the case in _Lepidosiren_,
+which possesses a convoluted oviduct with secretory glands in the
+middle of its length. The oviduct begins with a funnel-shaped
+dilatation, and terminates in a wide pouch, which posteriorly
+communicates with that of the other side, both opening by a common
+aperture behind the urinary bladder.
+
+The ova of Ganoids, as far as they are known at present, are small,
+but enveloped in a gelatinous substance. In the Sturgeon have been
+counted as many as 7,635,200. Those of _Lepidosteus_ seem to be the
+largest, measuring 5 millimetres in diameter with their envelope, and 3
+millimetres without it. They are deposited singly, like those of Newts.
+
+  [Illustration: Fig. 77.--Ovaries of Ceratodus.
+
+    _a_, Right ovary shown from the inner surface, which is
+    covered by the peritoneum; _a’_, Left ovary, showing its
+    outer surface; _l_, Portion of liver; _o_, Oviduct; _p_, the
+    lower part of the oviduct is opened to show the folds of its
+    inner membrane; _q_, Opening of the left oviduct into the
+    right; _r_, Abdominal orifice of the oviduct.]
+
+In _Chondropterygians_ (and _Holocephali_) the organs of reproduction
+assume a more compact form, and are more free from a lengthened
+attachment to the back of the abdominal cavity. The ovaries of the
+majority are paired, single in the _Carchariidæ_ and _Scylliidæ_, one
+remaining undeveloped. But the oviducts are always paired, beginning
+immediately behind the diaphragma with a common aperture. They consist
+of two divisions, separated by a circular valve; the upper is narrow,
+and provided within its coats with a gland which secretes the leathery
+envelope in which most of the Chondropterygian ova are enclosed; the
+lower forms the uterine dilatation, in which the embryoes of the
+viviparous species are developed. Generally the vitelline sac of the
+embryoes is free, and without connection with the uterus, which in
+these cases has merely the function of a protecting pouch; but in
+Carcharias and Mustelus lævis a _placenta uterina_ is formed, the
+vascular walls of the vitelline sac forming plaits fitting into those
+of the membrane of the uterus. The ends of the uteri open by a common
+aperture behind the ureter into the cloaca.
+
+  [Illustration: Fig. 78.--Ventral fins and claspers of
+  Chiloscyllium trispeculare.]
+
+The testicles are always paired, rounded, and situated in the anterior
+part of the abdominal cavity, covered by the liver. _Vasa efferentia_
+pass the semen into a much-convoluted _epididymis_, which is continued
+into the _vas deferens_; this, at the commencement of its course, is
+spirally wound, but becomes straight behind, and has its end dilated
+into a seminal reservoir. It opens with the urethra in a papilla within
+the cloaca.
+
+The so-called _claspers_ of Chondropterygians (Fig. 78) are
+characteristic of all male individuals. They are semi-ossified
+appendages of the pubic, with which they are movably joined, and
+special muscles serve to regulate their movements. Sometimes they
+are armed with hook-like osseous excrescences (_Selache_). They are
+irregularly longitudinally convoluted, and, when closely ad-pressed to
+each other, form a canal open at their extremity. A gland, abundantly
+discharging a secretion during the season of propagation, is situated
+at, and opens into, the base of the canal. It is still doubtful whether
+the generally-adopted opinion that their function consists in holding
+the female during copulation is correct, or whether they are not
+rather an intromittent organ, the canal of which not only conducts the
+secretion of their proper gland but also the impregnating fluid.
+
+  [Illustration: Fig. 79.--Egg of a Scyllium from Magelhan’s
+  Straits (? Sc. chilense). Natural size.]
+
+  [Illustration: Fig. 80.--Egg-shell of Cestracion philippi, half
+  natural size, linear.
+
+  I. External view. II. Vertical section.
+
+  _a_, One spiral ridge; _b_, The other spiral ridge;
+  _c_, Cavity for the ovum.]
+
+The ova of the oviparous Chondropterygians are large and few in number;
+they are successively impregnated, and the impregnation must take
+place before they are invested with a tough leathery envelope which
+would be impenetrable to the semen, that is, before they enter the
+uterus; therefore, copulation must take place in all these fishes. The
+form of the egg-shell differs in the various genera; generally (Fig.
+79) they are flattened, quadrangular, with each of the four corners
+produced, and frequently prolonged into long filaments which serve for
+the attachment of the ova to other fixed objects. In _Notidanus_ the
+surfaces are crossed by numerous ridges. In _Cestracion_ (Fig. 80) the
+egg is pyriform, with two broad ridges or plates, wound edgewise round
+it, the two ridges forming five spires. The eggs of _Callorhynchus_
+(Fig. 81) have received a protective resemblance to a broad-leaved
+fucus, forming a long depressed ellipse, with a plicated and fringed
+margin.
+
+  [Illustration: Fig. 81.--Egg of Callorhynchus antarcticus.
+  _a_, Cavity for the embryo.]
+
+
+
+
+                             CHAPTER XIII.
+
+                    GROWTH AND VARIATION OF FISHES.
+
+
+Changes of form normally accompanying growth (after absorption of the
+vitelline sac) are observed in all fishes; but in the majority they
+affect only the proportional size of the various parts of the body. In
+young fishes the eyes are constantly larger than in adult relatively
+to the size of the head; and again, the head is larger relatively to
+that of the body. Changes amounting to metamorphosis have been hitherto
+observed in _Petromyzon_ only. In the larval condition (_Ammocætes_)
+the head is very small, and the toothless buccal cavity is surrounded
+by a semicircular upper lip. The eyes are extremely small, hidden in a
+shallow groove; and the vertical fins form a continuous fringe. In the
+course of three or four years the teeth are developed, and the mouth
+changes into a perfect suctorial organ; the eyes grow; and the dorsal
+fin is divided into two divisions. In Malacopterygians and Anacanths
+the embryonal fringe from which the vertical fins are developed, is
+much longer persistent than in Acanthopterygians. A metamorphosis
+relating to the respiratory organs, as in Batrachians, is indicated in
+the class of Fishes by the external gills with which fœtal Plagiostomes
+(Fig. 58, p. 136) and the young of some Ganoids, viz. the _Protopterus_
+and _Polypterus_, are provided.
+
+  [Illustration: Fig. 82.--Mouth of Larva of Petromyzon
+  branchialis.]
+
+  [Illustration: Fig. 83.--Mouth of Petromyzon fluviatilis.
+
+   _mx_, Maxillary tooth; _md_, Mandibulary tooth;
+   _l_, Lingual tooth; _s_, Suctorial teeth.]
+
+  [Illustration: Fig. 84.--Armature of præoperculum of young Caranx
+  ferdau. (Magnified.)
+
+  I. Of an individual, 1¼ inch long. II. Of an individual, 2 inches
+  long.]
+
+  [Illustration: Fig. 85.--Tholichthys osseus. Six times the
+  natural size.]
+
+  [Illustration: Fig. 86.--Tholichthys-stage of Heniochus (?).]
+
+  [Illustration: Fig. 87.--Tholichthys-stage of Pomacanthus (magn.)
+  Atlantic.]
+
+  [Illustration: Fig. 88.--Young Chætodon citrinellus (30 mill.
+  long).]
+
+One of the most extraordinary changes by which, during growth, the
+form and position of several important organs are affected, occurs
+in Flat-fishes (_Pleuronectidæ_); their young are symmetrically
+formed, with a symmetrical mouth, and with one eye on each side, and,
+therefore, keep their body in a vertical position when swimming.
+As they grow they live more on the bottom, and their body, during
+rest, assumes a horizontal position; in consequence, the eye of the
+lower side moves towards the upper, which alone is coloured; and in
+many genera the mouth is twisted in the opposite direction, so that
+the bones, muscles, and teeth are much more developed on the blind
+side than on the coloured. In a great number of other _Teleostei_
+certain bones of the head show a very different form in the young
+state. Ossification proceeds in those bones in the direction of lines
+or radii which project in the form of spines or processes; as the
+interspaces between these processes are filled with bone, the processes
+disappear entirely, or at least project much less in the older than
+in the younger individuals (Fig. 84). The young of some fishes may be
+armed with a long powerful præopercular or scapular spine, or show
+a serrature of which nothing remains in the adult fish except some
+ridges or radiating lines. These processes seem to serve as weapons
+of defence during a period in the life of the fish in which it needs
+them most. In not a few instances a portion of this armature is so
+much developed that the disappearance of its most projecting parts
+with the growth of the fish is not only due to its being surrounded
+by other bone, but, partially at least, caused by absorption. The
+_Carangidæ_, _Cyttidæ_, _Squamipinnes_, _Xiphiidæ_, offer instances
+of such remarkable changes. A fish, described as _Tholichthys osseus_
+(Fig. 85), is probably the young of a Cyttoid, the suprascapula,
+humerus, and præoperculum forming enormously enlarged plates. In the
+fish Fig. 86 those bones appear still enlarged, and the frontals
+develop a remarkably long and curved horn above the orbit. In the
+_Tholichthys_-stage of _Pomacanthus_ (specimens 10 millimetres long,
+Fig. 87), the frontal bone is prolonged into a straight lancet-shaped
+process, nearly half as long as the body; the suprascapular and
+præopercular processes cover and hide the dorsal and ventral fins.
+The plates attached to the shoulder-girdle remain persistent until
+the young fish has assumed the form of the adult; thus they are still
+visible in young _Chætodon citrinellus_, 30 millimetres long, in which
+the specific characters are already fully developed.--The Sword-fishes
+with ventral fins (_Histiophorus_) belong to the Teleosteans of the
+largest size; in young individuals, 9 millimetres long (Fig. 89), both
+jaws are produced, and armed with pointed teeth; the supraorbital
+margin is ciliated; the parietal and præoperculum are prolonged
+into long spines; the dorsal and anal fins are a low fringe, and
+the ventrals make their appearance as a pair of short buds. When 14
+millimetres long (Fig. 90) the young fish has still the same armature
+of the head, but the dorsal fin has become much higher, and the
+ventral filaments have grown to a great length. At a third stage, when
+the fish has attained to a length of 60 millimetres, the upper jaw is
+considerably prolonged beyond the lower, losing its teeth; the spines
+of the head are shortened, and the fins assume nearly the shape which
+they retain in mature individuals. Young Sword-fishes without ventral
+fins (_Xiphias_) undergo similar changes; and, besides, their skin is
+covered with small rough excrescences longitudinally arranged, which
+continue to be visible after the young fish has assumed the form of the
+mature in other respects (Fig. 92).
+
+  [Illustration: Fig. 89.--Young Sword-fish (Histiophorus), 9 mill.
+  long. Atlantic. (Magn.)]
+
+  [Illustration: Fig. 90.--Young Sword-fish (Histiophorus), 14
+  mill. long. South Atlantic. (Magn.)]
+
+  [Illustration: Fig. 91.--Young Sword-fish (Histiophorus), 60
+  mill. long. Mid-Atlantic.]
+
+  [Illustration: Fig. 92.--Xiphias gladius, young, about 8 inches
+  long.]
+
+The Plectognaths show no less extraordinary changes: an extraordinary
+form taken in the South Atlantic, and named _Ostracion boops_, is
+considered by Lütken to be the young of a Sun-fish (_Orthagoriscus_).
+In very young more advanced Sun-fishes (18 to 32 millimetres) the
+vertical diameter of the body exceeds, or is not much less than, the
+longitudinal; and small conical spines are scattered over its various
+parts. The caudal fin is developed long after the other vertical fins.
+
+  [Illustration: Fig. 93.--“Ostracion boops” (much magnified).]
+
+  [Illustration: Fig. 94.--Young of Orthagoriscus, 18 and 32 mill.
+  long. (Natural size.)]
+
+Similar changes take place in a number of other fishes, and in
+many cases the young are so different that they were described as
+distinct genera: thus _Priacantichthys_ has proved to be the young of
+_Serranus_, _Rhynchichthys_ that of _Holocentrum_, _Cephalacanthus_ of
+_Dactylopterus_, _Dicrotus_ of _Thyrsites_, _Nauclerus_ of _Naucrates_,
+_Porthmeus_ of _Chorinemus_, _Lampugus_ of _Coryphæna_, _Acronurus_
+of _Acanthurus_, _Keris_ of _Naseus_, _Porobronchus_ of _Fierasfer_,
+_Couchia_ of _Motella_, _Stomiasunculus_ of _Stomias_, etc.
+
+The fins are most frequently subject to changes; but, whilst in some
+fishes parts of them are prolonged into filaments with age, in others
+the filaments exist during the early life-periods only; whilst in some
+a part of the dorsal or the ventral fins is normally developed in the
+young only, in others those very parts are peculiar to the mature age.
+The integuments are similarly altered: in some species the young only
+has asperities on the skin, in others the young are smooth and the old
+have a tubercular skin; in some the young only have a hard bony head;
+in others (some Siluroids) the osseous carapace of the head and neck,
+as it appears in the adult, is more or less covered with soft skin
+whilst the fish is young.
+
+In not a few fishes the external changes are in relation to the sexual
+development (_Callionymus_, many _Labyrinthici_, Cyprinodonts). These
+_secondary sexual differences_ show themselves in the male individual,
+only when it commences to enter upon his sexual functions, and it may
+require two or more seasons before its external characteristics are
+fully developed. Immature males do not differ externally from the old
+female. The male secondary sexual characters consist principally in
+the prolongation of some of the fin-rays, or of entire fins; and in
+_Salmonidæ_ in the greater development of the jaw-bones. The coloration
+of the male is in many fishes much brighter and more variegated than
+that of the female, but in comparatively few permanent (as in some
+_Callionymus_, _Labrus mixtus_); generally it is acquired immediately
+before and during the season of propagation only, and lost afterwards.
+Another periodical change in the integuments, also due to sexual
+influence and peculiar to the male, is the excrescence of wart-like
+tubercles on the skin of many _Cyprinoids_; they are developed chiefly
+on the head, but sometimes extend over the whole body and all the fins.
+
+With regard to size, it appears that in all Teleosteous fishes the
+female is larger than the male; in many Cyprinodonts the male may be
+only one-sixth or even less of the bulk of the female. The observations
+on the relative size of the sexes are few in Palæichthyes, but such as
+have been made tend to show that, if a difference exists at all, the
+male is generally the larger (_Lepidosteus_). In the Rays (_Raja_) the
+sexes, after they have attained maturity, differ in the development of
+dermal spines and the form of the teeth, the female being frequently
+much rougher than the male. There is much variation in this respect in
+the different species; but the males are constantly distinguished by
+an oblong patch of erectile claw-like spines on each pectoral fin, and
+by having the teeth (all, or only a portion) pointed, and not obtuse,
+like those of the females. In Sharks no secondary sexual differences
+have been observed; the male _Chimæridæ_ (see Fig. 96, p. 184), possess
+a singular comb-like cartilaginous appendage on the top of the head,
+which can be erected or depressed into a groove, both the appendage and
+the anterior part of the groove being armed with hooklets. The use of
+this singular organ is not known.
+
+The majority of Teleostei are _mixogamous_--that is, the males and
+females congregate on the spawning-beds, and the number of the former
+being in excess, several males attend to the same female, frequently
+changing from one female to another. The same habit has been observed
+in _Lepidosteus_. _Gastrosteus_ is truly polygamous, several females
+depositing their ova into the same nest, guarded by one male only. Some
+Teleostei (_Ophiocephalus_), and probably all Chondropterygians, are
+monogamous; and it is asserted that the connection between the pair is
+not merely temporary, but lasts until they are separated by accident.
+Monogamous are probably also all those Teleosteans which bring forth
+living young, and those, the males of which, for the attraction of
+the female, are provided with appendages, or ornamented with a bright
+coloration.
+
+_Hybridism_ is another source of changes and variations within the
+limits of a species, and is by no means so scarce as has been believed
+hitherto; it is only apparently of exceptional occurrence, because
+the life of fishes is more withdrawn from our direct observation than
+that of terrestrial animals. It has been observed among species of
+_Serranus_, _Pleuronectidæ_, _Cyprinidæ_, _Clupeidæ_, and especially
+_Salmonidæ_. As in other animals, the more certain kinds of fishes
+are brought under domestication, the more readily do they interbreed
+with other allied species. It is characteristic of hybrids that their
+characters are very variable, the degrees of affinity to one or the
+other of the parents being inconstant; and as these hybrids are known
+readily to breed with either of the parent race, the variations of
+form, structure, and colour are infinite. Of internal organs the
+dentition, gill-rakers, pyloric appendages, are those particularly
+affected by such mixture of species.
+
+       *       *       *       *       *
+
+Some fishes are known to grow rapidly (in the course of from one to
+three years) and regularly to a certain size, growth being definitely
+arrested after the standard has been attained. Such fishes may be
+called “full-grown,” in the sense in which the term is applied to
+warm-blooded Vertebrates--the Sticklebacks, most Cyprinodonts, and many
+Clupeoids (Herring, Sprat, Pilchard) are examples of this regular
+kind of growth.[15] But in the majority of fishes the rate of growth
+is extremely irregular, and it is hardly possible to know when growth
+is actually and definitely arrested. All seems to depend on the amount
+of food and the more or less favourable circumstances under which the
+individual grows up. Fishes which rapidly grow to a definite size are
+short-lived, whilst those which steadily and slowly increase in size
+attain to a great age, Teleosteans as well as Chondropterygians. Carp
+and Pike have been ascertained to live beyond a hundred years.
+
+It is evident that such diversity and irregularity of growth in
+the same species is accompanied by considerable differences in the
+appearance and general development of the fish. No instance is more
+remarkable than that of the so-called _Leptocephali_, which for a
+long time have been regarded either as a distinct group of Fishes, or
+as the larval stages of various genera of fishes.
+
+  [Illustration: Fig. 95.--Leptocephalus.]
+
+The _Leptocephali_ proper are small, narrow, elongate, more or less
+band-shaped fishes, pellucid in a fresh state, but assuming a white
+colour when preserved in spirits, resembling a tapeworm, being quite
+as soft and flexible. The skeleton is entirely cartilaginous, or
+slight ossifications are only now and then visible, especially towards
+the end of the vertebral column. The latter is replaced by a chorda
+dorsalis which, in many specimens, is found to be divided into numerous
+segments. Neural arches are sometimes present in their rudimentary
+condition. The anterior end of the chorda passes into the cartilaginous
+base of the skull, the connection not being by means of joint and
+ligaments. Hæmal arches are found on the caudal portion. Ribs none. The
+skull, like the vertebral column, is nearly entirely cartilaginous.
+The basisphenoid, frontal, and jaw-bones are the first which may be
+distinguished, and the mandible has generally ossifications.
+
+The muscles are generally not attached to the chorda, which is
+surrounded by a thick gelatinous mass, separating the lateral sets of
+muscles from each other. These muscles are attached to the external
+integument, each forming a thin flat angular band, the angle being
+directed forwards. However, specimens are frequently found in which the
+muscles are more developed, evidently at the expense of the gelatinous
+matter, which is diminished in quantity. They are attached to the
+chorda, and the entire fish has a more cylindrical form of the body
+(_Helmichthys_).
+
+The nervous, circulatory, and respiratory organs are well developed.
+In those with a sub-cylindrical body the blood is red, in those with
+a flat body the blood-corpuscles show but rarely a faint coloration.
+There are four branchial arches, and in some (_Tilurus_) pseudobrauchiæ
+have been found. The gill-openings are more or less narrow. The
+nostrils are double on each side, and the posterior is close to the eye.
+
+The stomach has a large blind sac, and in _Leptocephalus_ two lateral
+cæca. The intestine is straight, running close to the abdominal
+profile, with a small appendix directed forward and a larger one
+directed backwards. The vent is nearly always very small, and, in
+preserved examples at least, cannot always be discovered. Its position
+is variable, even in examples entirely similar in other points.
+Air-bladder none. No trace of generative organs.
+
+The vertical fins, when present, are confluent, with more or less
+conspicuous traces of rays; sometimes they are merely a fold of the
+skin, without any rays. Pectoral fins sometimes present, sometimes
+rudimentary, sometimes entirely absent. Ventrals none.
+
+Most examples have series of round black dots along each side of the
+abdominal profile, along the lateral line, and sometimes along the
+dorsal fin. They remind us of the luminous organs of many _Scopelidæ_,
+_Stomiatidæ_, and other pelagic fishes, but are composed entirely of
+pigmentary cells.
+
+These fishes are found floating in the sea, frequently at a great
+distance from land. Their movements are slow and languid. The largest
+specimen of Leptocephalus observed was 10 inches, but specimens of that
+size are very rare.
+
+   [See Kölliker, Zeitschr. wiss. Zool. iv. 1852, p. 360; and
+   Carus, Ueber die Leptocephaliden. Leipz. 1861. 4to.]
+
+Taking into account all the various facts mentioned, we must come to
+the conclusion that the Leptocephalids are the offspring of various
+kinds of marine fishes, representing, not a normal stage of development
+(larvæ), but an arrest of development at a very early period of their
+life; they continue to grow to a certain size without corresponding
+development of their internal organs, and perish without having
+attained the characters of the perfect animal. The cause by which this
+abnormal condition is brought about is not known; but it is quite
+within the limits of probability that fishes usually spawning in the
+vicinity of land sometimes spawn in the open ocean, or that floating
+spawn is carried by currents to a great distance from land; and that
+such embryoes, which for their normal growth require the conditions
+afforded by the vicinity of the shore, if hatched in mid-ocean, grow
+into undeveloped hydropic creatures, such as the Leptocephales seem to
+be.
+
+       *       *       *       *       *
+
+Abundance or scarcity of food, and other circumstances connected with
+the localities inhabited by fishes, affect considerably the colour of
+their muscles and integuments; the periodical changes of colour in
+connection with their sexual functions have been referred to above (p.
+176). The flesh of many Teleostei is colourless, or but slightly tinged
+by the blood; that of Scombridæ, most Ganoids and Chondropterygians,
+is more or less red; but in badly-fed fishes, as well as in very
+young ones, the flesh is invariably white (anæmic). Many fishes, like
+the _Salmonidæ_, feed at times exclusively on Crustaceans, and the
+colouring substance of these Invertebrates, which by boiling and by
+the stomachic secretion turns red, seems to pass into the flesh of the
+fishes, imparting to it the well-known “salmon” colour. Further, the
+coloration of the integuments of many marine fish is dependent on the
+nature of their surroundings. In those which habitually hide themselves
+on the bottom, in sand, between stones or seaweeds, the colours of
+the body readily assimilate to those of the vicinity, and are thus
+an important element in the economy of their life. The changes from
+one set or tinge of colours to another may be rapid and temporary, or
+more or less permanent; in some fishes--as in the Pediculati, of which
+the Sea-Devil, or _Lophius_, and _Antennarius_ are members--scarcely
+two individuals are found exactly alike in coloration, and only
+too frequently such differences in coloration are mistaken for
+specific characters. The changes of colours are produced in two ways:
+either by an increase or decrease of the black, red, yellow, etc.,
+pigment-cells, or _chromatophors_, in the skin of the fish; or by the
+rapid contraction or expansion of the chromatophors which happen to
+be developed. The former change is gradual, like every kind of growth
+or development; the latter rapid, owing to the great sensitiveness
+of the cells, but certainly involuntary. In many bright-shining
+fishes--as Mackerels, Mullets--the colours appear to be brightest in
+the time intervening between the capture of the fish and its death: a
+phenomenon clearly due to the pressure of the convulsively-contracted
+muscles on the chromatophors. External irritation readily excites the
+chromatophors to expand--a fact unconsciously utilised by fishermen,
+who, by scaling the Red Mullet immediately before its death, produce
+the desired intensity of the red colour of the skin, without which the
+fish would not be saleable. However, it does not require such strong
+measures to prove the sensitiveness of the chromatophors to external
+irritation, the mere change of darkness into light is sufficient to
+induce them to contract, the fish appearing paler, and _vice versa_. In
+Trout which are kept or live in dark places, the black chromatophors
+are expanded, and, consequently, such specimens are very dark-coloured;
+when removed to the light they become paler almost instantaneously.
+
+Total absence of chromatophors in the skin, or _Albinism_, is very rare
+among fishes; much more common is _incipient Albinism_, in which the
+dark chromatophors are changed into cells with a more or less intense
+yellow pigment. Fishes in a state of domestication, like the Crucian
+Carp of China, the Carp, Tench, and the Ide, are particularly subject
+to this abnormal coloration, and are known as the common Gold-fish, the
+Gold-Tench, and the Gold-Orfe. But it occurs also not rarely in fishes
+living in a wild state, and has been observed in the Haddock, Flounder,
+Plaice, Carp, Roach, and Eel.
+
+It will be evident, from the foregoing remarks, that the amount of
+variation within the limits of the same species--either due to the
+natural growth and development, or to external physical conditions,
+or to abnormal accidental circumstances--is greater in fishes than
+in any of the higher classes of Vertebrates. The amount of variation
+is greater in certain genera or families than in others, and it is
+much greater in Teleosteans and Ganoids than in Chondropterygians.
+Naturally, it is greatest in the few species which have been
+domesticated, and which we shall mention in the succeeding chapter.
+
+   [Illustration: Fig. 96.--Chimæra colliei ♂, west coast of
+  North America. A. Front view of head. B. Palate. _a_, Peritoneal
+  aperture; _b_, Nostrils; _c_, Vomerine teeth; _d_, Mandibular
+  teeth; _e_, Palatine teeth; _f_, Claspers.]
+
+
+
+
+                             CHAPTER XIV.
+
+     DOMESTICATED AND ACCLIMATISED FISHES; ARTIFICIAL IMPREGNATION
+           OF OVA--TENACITY OF LIFE AND REPRODUCTION OF LOST
+           PARTS--HYBERNATION--USEFUL AND POISONOUS FISHES.
+
+
+A few fishes only are thoroughly domesticated--that is, bred in
+captivity, and capable of transportation within certain climatic
+limits--viz. the Carp, Crucian Carp (European and Chinese varieties),
+Tench, Orfe or Ide, and the Goramy. The two former have accompanied
+civilised man almost to every place of the globe where he has effected
+a permanent settlement.
+
+Attempts to acclimatise particularly useful species in countries in
+which they were not indigenous have been made from time to time, but
+were permanently successful in a few instances only; the failures
+being due partly to the choice of a species which did not yield the
+profitable return expected, partly to the utter disregard of the
+difference of the climatic and other physical conditions between the
+original and new homes of the fish. The first successful attempts of
+acclimatisation were made with domestic species, viz. the Carp and
+Gold-fish, which were transferred from Eastern Asia to Europe. Then,
+in the first third of the present century, the Javanese Goramy was
+acclimatised in Mauritius and Guiana, but no care seems to have been
+taken to insure permanent advantages from the successful execution
+of the experiment. In these cases fully developed individuals were
+transported to the country in which they were to be acclimatised. The
+most successful attempt of recent years is the acclimatisation of the
+Trout and Sea-Trout, and probably also of the Salmon, in Tasmania and
+New Zealand, and of the Californian Salmon (_Salmo quinnat_?),
+in Victoria, by means of artificially-impregnated ova. The ova were
+transported on ice, in order to retard their development generally,
+and thus to preserve them from destruction during the passage of the
+tropical zone.
+
+_Artificial impregnation_ of fish-ova was first practised by
+J. L. JACOBI, a native of Westphalia, in the years 1757–63,
+who employed exactly the same method which is followed now; and there
+is no doubt that this able observer of nature conceived and carried
+out his idea with the distinct object of advantageously restocking
+water-courses which had become unproductive, and increasing production
+by fecundating and preserving all ova, of which a great proportion,
+in the ordinary course of propagation, would be left unfecundated
+or accidentally perish. Physiology soon turned to account Jacobi’s
+discovery, and artificial impregnation has proved to be one of the
+greatest helps to the student of embryology.
+
+Fishes differ in an extraordinary degree with regard to tenacity of
+life. Some will bear suspension of respiration--caused by removal from
+water, or by exposure to cold or heat--for a long time, whilst others
+succumb at once. Nearly all marine fishes are very sensitive to changes
+in the temperature of the water, and will not bear transportation from
+one climate to another. This seems to be much less the case with some
+freshwater fishes of the temperate zones: the Carp may survive after
+being frozen in a solid block of ice, and will thrive in the southern
+parts of the temperate zone. On the other hand, some freshwater
+fishes are so sensitive to a change in the water that they perish
+when transplanted from their native river into another apparently
+offering the same physical conditions (Grayling, _Salmo hucho_).
+Some marine fishes may be abruptly transferred from salt into fresh
+water, like Sticklebacks, some Blennies, and _Cottus_, etc.;
+others survive the change when gradually effected, as many migratory
+fishes; whilst again, others cannot bear the least alteration in the
+composition of the salt water (all pelagic fishes). On the whole,
+instances of marine fishes voluntarily entering brackish or fresh water
+are very numerous, whilst freshwater fishes proper but rarely descend
+into salt water.
+
+Abstinence from food affects different fishes in a similarly different
+degree. Marine fishes can endure hunger less than freshwater fishes,
+at least in the temperate zones, no observations having been made in
+this respect on tropical fishes. Goldfishes, Carps, Eels, are known to
+be able to subsist without food for months, without showing a visible
+decrease of bulk; whilst the Trigloids, Sparoids, and other marine
+fishes, survive abstinence from food for a few days only. In freshwater
+fishes the temperature of the water is of great influence on their
+vital functions generally, and consequently on their appetite,--many
+cease to feed altogether in the course of the winter; a few, like the
+Pike, are less inclined to feed during the heat of the summer than when
+the temperature is lowered.
+
+Captivity is easily borne by most fishes, and the appliances introduced
+in our modern aquaria have rendered it possible to keep in confinement,
+and even to induce to propagate, fishes which formerly were considered
+to be intolerant of captivity.
+
+Wounds affect fishes generally much less than higher Vertebrates. A
+Greenland Shark continues to feed whilst his head is pierced by a
+harpoon or by the knife, as long as the nervous centre is not touched;
+a Sea-perch or a Pike (Fig. 97) will survive the loss of a portion of
+its tail; a Carp that of half of its snout. However, some fishes are
+much more sensitive, and perish even from the superficial abrasion
+caused by the meshes of the net during capture (_Mullsn_.)
+
+The power of _reproduction_ of _lost parts_ in Teleosteous fishes is
+limited to the delicate terminations of their fin-rays and the various
+tegumentary filaments with which some are provided. These filaments are
+sometimes developed in an extraordinary degree, mimicking the waving
+fronds of the seaweed in which the fish hides. Both the ends of the
+fin-rays and the filaments are frequently lost, not only by accident,
+but merely by wear and tear; and as these organs are essential for the
+preservation of the fish, their reproduction is necessary.
+
+  [Illustration: Fig. 97.--Pike caught in the Thames, which, when
+  young, had lost part of the tail with the caudal fin.]
+
+In Dipnoi, _Ceratodus_, and _Protopterus_, the terminal portion of the
+tail has been found to have been reproduced, but without the notochord.
+
+       *       *       *       *       *
+
+_Hybernation_ has been observed in many Cyprinoids and Murænoids
+of the temperate zones. They do not fall into a condition of complete
+torpidity, as Reptiles and Mammals, but their vital functions are
+simply lowered, and they hide in sheltered holes, and cease to go
+abroad in search of their food. Between the tropics a great number
+of fishes (especially Siluroids, Labyrinthici, Ophiocephaloids, the
+Dipnoi), are known to survive long-continued droughts by passing the
+dry season in a perfectly torpid state, imbedded in the hardened mud.
+Protopterus, and probably many of the other fishes mentioned, prepare
+for themselves a cavity large enough to hold them, and coated on the
+inside with a layer of hardened mucus, which preserves them from
+complete desiccation. It has been stated that in India fishes may
+survive in this condition for more than one season, and that ponds
+known to have been dry for several years, and to the depth of many
+feet, have swarmed with fishes as soon as the accumulation of water
+released them from their hardened bed.
+
+       *       *       *       *       *
+
+The principal _use_ derived by man from the class of Fishes consists in
+the abundance of wholesome and nourishing food which they yield. In the
+Polar regions especially, whole tribes are entirely dependent on this
+class for subsistence; and in almost all nations fishes form a more or
+less essential part of food, many being, in a preserved condition, most
+important articles of trade. The use derived by man from them in other
+respects is of but secondary importance. Cod-liver oil is prepared from
+the liver of some of the Gadoids of the Northern Hemisphere, and of
+Sharks; isinglass from the swim-bladder of Sturgeons, Sciænoids, and
+Polynemoids; shagreen from the skin of Sharks and Rays.
+
+       *       *       *       *       *
+
+The flesh of some fishes is at times, or constantly, _poisonous_.
+When eaten, it causes symptoms of more or less intense irritation of
+the stomach and intestines, inflammation of the mucous membranes, and
+not rarely death. The fishes, the flesh of which appears always to
+have poisonous properties, are _Clupea thrissa_, _Clupea venenosa_,
+and some species of _Scarus_, _Tetrodon_, and _Diodon_. There are
+many others which have occasionally or frequently caused symptoms of
+poisoning. Poey enumerates not less than seventy-two different kinds
+from Cuba; and various species of _Sphyræna_, _Balistes_, _Ostracion_,
+_Caranx_, _Lachnolæmus_, _Tetragonurus_, _Thynnus_, have been found
+to be poisonous in all seas between the tropics. All or nearly all
+these fishes acquire their poisonous properties from their food which
+consists of poisonous Medusæ, Corals, or decomposing substances.
+Frequently the fishes are found to be eatable if the head and
+intestines be removed immediately after capture. In the West Indies it
+has been ascertained that all the fishes living and feeding on certain
+coral banks are poisonous. In other fishes the poisonous properties are
+developed at certain seasons of the year only, especially the season of
+propagation: as the Barbel, Pike, and Burbot, whose roe causes violent
+diarrhœas when eaten during the season of spawning.
+
+       *       *       *       *       *
+
+  [Illustration: Fig. 98.--Portion of tail, with spines, of
+  _Aëtobatis narinari_, a Sting-ray from the Indian Ocean.
+  _a_, nat. size.]
+
+_Poison-organs_ are more common in the class of Fishes than was
+formerly believed, but they seem to have exclusively the function
+of defence, and are not auxiliary in procuring food, as in venomous
+Snakes. Such organs are found in the Sting-rays, the tail of which is
+armed with one or more powerful barbed spines. Although they lack a
+special organ secreting poison, or a canal in or on the spine by which
+the venomous fluid is conducted, the symptoms caused by a wound from
+the spine of a Sting-ray are such as cannot be accounted for merely by
+the mechanical laceration, the pain being intense, and the subsequent
+inflammation and swelling of the wounded part terminating not rarely
+in gangrene. The mucus secreted from the surface of the fish and
+inoculated by the jagged spine evidently possesses venomous properties.
+This is also the case in many Scorpænoids, and in the Weaver
+(_Trachinis_), in which the dorsal and opercular spines have the
+same function as the caudal spines of the Sting-rays; however, in the
+Weavers the spines are deeply grooved, the groove being charged with a
+fluid mucus. In _Synanceia_ the poison-organ (Fig. 99,) is still
+more developed: each dorsal spine is in its terminal half provided
+with a deep groove on each side, at the lower end of which lies a
+pear-shaped bag containing the milky poison; it is prolonged into a
+membranous duct, lying in the groove of the spine, and open at its
+point. The native fishermen, well acquainted with the dangerous nature
+of these fishes, carefully avoid handling them; but it often happens
+that persons wading with naked feet in the sea, step upon the fish,
+which generally lies hidden in the sand. One or more of the erected
+spines penetrate the skin, and the poison is injected into the wound by
+the pressure of the foot on the poison-bags. Death has not rarely been
+the result.
+
+  [Illustration: Fig. 99.--A dorsal spine, with poison-bags, of
+  _Synanceia verrucosa_. Indian Ocean.]
+
+  [Illustration: Fig. 100.--Opercular part of the Poison-apparatus
+  of _Thalassophryne_ (Panama).
+
+  1. Hinder half of the head, with the venom-sac* _in situ._
+  _a_, Lateral line and its branches; _b_, Gill-opening;
+  _c_, Ventral fin; _d_, Base of Pectoral fin; _e_,
+  Base of dorsal.
+
+  2. Operculum with the perforated spine.]
+
+The most perfect poison-organs hitherto discovered in fishes are those
+of _Thalassophryne_, a Batrachoid genus of fishes from the coasts of
+Central America. In these fishes the operculum again and the two dorsal
+spines are the weapons. The former (Fig. 100, ^2) is very narrow,
+vertically styliform and very mobile; it is armed behind with a spine,
+eight lines long, and of the same form as the hollow venom-fang of
+a snake, being perforated at its base and at its extremity. A sac
+covering the base of the spine discharges its contents through the
+apertures and the canal in the interior of the spine. The structure of
+the dorsal spines is similar. There are no secretory glands imbedded
+in the membranes of the sacs; and the fluid must be secreted by their
+mucous membrane. The sacs are without an external muscular layer, and
+situated immediately below the thick loose skin which envelops the
+spines to their extremity; the ejection of the poison into a living
+animal, therefore, can only be effected, as in _Synanceia_, by the
+pressure to which the sac is subjected the moment the spine enters
+another body.
+
+Finally, a singular apparatus found in many Siluroids may be mentioned
+in connection with the poison-organs, although its function is still
+problematical. Some of these fishes are armed with powerful pectoral
+spines and justly feared on account of the dangerous wounds they
+inflict; not a few of them possess, in addition to the pectoral spines,
+a sac with a more or less wide opening in the axil of the pectoral fin;
+and it does not seem improbable that it contains a fluid which may be
+introduced into a wound by means of the pectoral spine, which would
+be covered with it, like the barbed arrow-head of an Indian. However,
+whether this secretion is equally poisonous in all the species provided
+with that axillary sac, or whether it has poisonous qualities at all,
+is a question which can be decided by experiments only made with the
+living fishes.
+
+
+
+
+                              CHAPTER XV.
+
+                    DISTRIBUTION OF FISHES IN TIME.
+
+
+Of what kind the fishes were which were the first to make their
+appearance on the globe; whether or not they were identical with,
+or similar to, any of the principal types existing at present; are
+questions which probably will for ever remain hidden in mystery and
+uncertainty. The supposition that the Leptocardii and Cyclostomes,
+the lowest of the vertebrate series, must have preceded the other
+sub-classes, is an idea which has been held by many Zoologists: and
+as the horny teeth of the Cyclostomes are the only parts of their
+body which under favourable circumstances might have been preserved,
+Palæontologists have ever been searching for this evidence.
+
+  [Illustration: Fig. 101. Right dental plate of Myxine affinis.]
+
+Indeed, in deposits belonging to the Lower Silurian and Devonian, in
+Russia, England, and North America, minute, slender, pointed horny
+bodies, bent like a hook, with sharp opposite margins, have been found
+and described under the name of _Conodonts_. More frequently they
+possess an elongated basal portion, in which there is generally a
+larger tooth with rows of similar but smaller denticles on one or both
+sides of the larger tooth, according as this is central or at one end
+of the base. In other examples there is no prominent central tooth,
+but a series of more or less similar teeth is implanted on a straight
+or curved base. Modifications of these arrangements are very numerous,
+and many Palæontologists entertain still doubts whether the origin
+of these remains is not rather from Annelids and Mollusks than from
+Fishes.
+
+   [See G. J. Hinde, in “Quarterly Journal of the Geological
+   Society,” 1879.]
+
+The first undeniable evidence of a fish, or, indeed, of a vertebrate
+animal, occurs in the _Upper Silurian_ Rocks, in a bone-bed of the
+Downton sandstone, near Ludlow. It consists of compressed, slightly
+curved, ribbed spines, of less than two inches in length (_Onchus_); of
+small shagreen-scales (_Thelodus_); the fragment of a jaw-like bar with
+pluricuspid teeth (_Plectrodus_); the cephalic bucklers of what seems
+to be a species of _Pteraspis_; and, finally, the coprolitic bodies
+of phosphate and carbonate of lime, including recognisable remains of
+the Mollusks and Crinoids inhabiting the same waters. But no vertebra
+or other part of the skeleton has been found. The spines and scales
+seem to have belonged to the same kind of fish, which probably was a
+Plagiostome. It is quite uncertain whether or not the jaw (if it be the
+jaw of a fish[16]) belonged to the buckler-bearing _Pteraspis_, the
+position of which among Ganoids, with which it is generally associated,
+is open to doubt.
+
+No detached undoubted tooth of a Plagiostome or Ganoid scale has been
+discovered in the Ludlow deposits: but so much is certain that those
+earliest remains in Palæozoic rocks belonged to fishes closely allied
+to forms occurring in greater abundance in the succeeding formation,
+the Devonian, where they are associated with undoubted Palæichthyes,
+Plagiostomes as well as Ganoids.
+
+       *       *       *       *       *
+
+These fish-remains of the _Devonian_ or _Old Red Sandstone_, can be
+determined with greater certainty. They consist of spines or the
+so-called _Ichthyodorulites_, which show sufficiently distinctive
+characters to be referred to several genera, one of them, _Onchus_,
+still surviving from the Silurian epoch. All these spines are believed
+to be those of Chondropterygians, to which order some pluricuspid
+teeth (_Cladodus_) from the Old Red Sandstone in the vicinity of St.
+Petersburg have been referred likewise.
+
+The remains of the Ganoid fishes are in a much more perfect state of
+preservation, so that it is even possible to obtain a tolerably certain
+idea of the general appearance and habits of some of them, especially
+of such as were provided with hard carapaces, solid scales, and
+ordinary or bony fin-rays. A certain proportion of them, as might have
+been expected, remind us, with regard to external form, of Teleosteous
+fishes rather than of any of the few still existing Ganoid types; but
+it is contrary to all analogy and to all palæontological evidence
+to suppose that those fishes were, with regard to their internal
+structure, more nearly allied to Teleosteans than to Ganoids. If they
+were not true Ganoids, they may be justly supposed to have had the
+essential characters of Palæichthyes. Other forms exhibit even at that
+remote geological epoch so unmistakably the characteristics of existing
+Ganoids, that no one can entertain any doubt with regard to their place
+in the system. In none of these fishes is there any trace of vertebral
+segmentation.
+
+The Palæichthyes of the Old Red Sandstone, the systematic position
+of which is still obscure, are the _Cephalaspidæ_ from the Lower Old
+Red Sandstone of Great Britain and Eastern Canada; _Pterichthys_,
+_Coccosteus_, and _Dinichthys_: genera which have been combined in
+one group--_Placodermi_; and _Acanthodes_ and allied genera, which
+combined numerous branchiostegals with chondropterygian spines and a
+shagreen-like dermal covering.
+
+Among the other Devonian fishes (and they formed the majority) two
+types may be recognised, both of which are unmistakably Ganoids. The
+first approaches the still living _Polypterus_, with which some of the
+genera like _Diplopterus_ singularly agree in the form and armature of
+the head, the lepidosis of the body, the lobate pectoral fins, and the
+termination of the vertebral column. Other genera, as _Holoptychius_,
+have cycloid scales; many have two dorsal fins (_Holoptychius_), and,
+instead of branchiostegals, jugular scutes; others one long dorsal
+confluent with the caudal (_Phaneropleuron_).
+
+In the second type the principal characters of the _Dipnoi_ are
+manifest, and some of them, for example _Dipterus_, _Palædaphus_,
+_Holodus_, approach so closely the Dipnoi which still survive, that the
+differences existing between them warrant a separation into families
+only.
+
+Devonian fishes are frequently found under peculiar circumstances,
+enclosed in the so-called _nodules_. These bodies are elliptical
+flattened pebbles, which have resisted the action of water in
+consequence of their greater hardness, whilst the surrounding rock has
+been reduced to detritus by that agency. Their greater density is due
+to the dispersion in their substance of the fat of the animal which
+decomposed in them. Frequently, on cleaving one of these nodules with
+the stroke of the hammer, a fish is found embedded in the centre. At
+certain localities of the Devonian, fossil fishes are so abundant
+that the whole of the stratum is affected by the decomposing remains
+emitting a peculiar smell when newly opened, and acquiring a density
+and durability not possessed by strata without fishes. The flagstones
+of Caithness are a remarkable instance of this.
+
+       *       *       *       *       *
+
+The fish-remains of the _Carboniferous_ formation show a great
+similarity to those of the preceding. They occur throughout the series,
+but are very irregularly distributed, being extremely scarce in some
+countries, whilst in others entire beds (the so-called bone-beds) are
+composed of ichthyolites. In the ironstones they frequently form the
+nuclei of nodules, as in the Devonian.
+
+Of Chondropterygians the spines of _Onchus_ and others still occur,
+with the addition of teeth indicative of the existence of fishes
+allied to the Cestracion-type (_Cochliodus_, _Psammodus_): a type
+which henceforth plays an important part in the composition of the
+extinct marine fish faunæ. Another extinct Selachian family, that of
+Hybodontes, makes its appearance, but is known from the teeth only.
+
+Of the Ganoid fishes, the family _Palæoniscidæ_ (Traquair) is
+numerously represented; others are Cœlacanths (_Cœlocanthus_,
+_Rhizodus_), and _Saurodipteridæ_ (_Megalichthys_). None of these
+fishes have an ossified vertebral column, but in some (_Megalichthys_)
+the outer surface of the vertebræ is ossified into a ring; the
+termination of their tail is heterocercal. The carboniferous _Uronemus_
+and the Devonian _Phaneropleuron_ are probably generically the same;
+and the Devonian _Dipnoi_ are continued as, and well represented by,
+_Ctenodus_.
+
+       *       *       *       *       *
+
+The fishes of the _Permian_ group are very similar to those of the
+Carboniferous. A type which in the latter was but very scantily
+represented, namely the _Platysomidæ_, is much developed. They were
+deep-bodied fish, covered with hard rhomboid scales possessing a strong
+anterior rib, and provided with a heterocercal caudal, long dorsal and
+anal, short non-lobate paired fins (when present), and branchiostegals.
+The _Palæoniscidæ_ are represented by many species of _Palæoniscus_,
+_Pygopterus_ and _Acrolepis_, and Cestracionts by _Janassa_ and
+_Strophodus_.
+
+       *       *       *       *       *
+
+The passage from the Palæozoic into the _Mesozoic_ era is not
+indicated by any marked change as far as fishes are concerned. The
+more remarkable forms of the Trias are Shark-like fishes represented
+by ichthyodorulithes like _Nemacanthus_, _Liacanthus_, and _Hybodus_;
+and Cestracionts represented by species of _Acrodus_ and _Strophodus_.
+Of the Ganoid genera _Cœlacanthus_, _Amblypterus_ (_Palæoniscidæ_),
+_Saurichthys_ persist from the Carboniferous epoch. _Ceratodus_ appears
+for the first time (Muschel-Kalk of Germany).
+
+Thanks to the researches of Agassiz, and especially Sir P. Egerton,
+the ichthyological fauna of the Lias is, perhaps, the best known of
+the Mesozoic era, 152 species having been described. Of the various
+localities, Lyme Regis has yielded more than any other, nearly
+all the Liassic genera being represented there by not less than
+seventy-nine species. The Hybodonts and Cestracionts continue in
+their fullest development. Holocephales (_Ischyodus_), true Sharks
+(_Palæoscyllium_), Rays (_Squaloraja_, _Arthropterus_), and Sturgeons
+(_Chondrosteus_) make their first appearance; but they are sufficiently
+distinct from living types to be classed in separate genera, or even
+families. The Ganoids, especially Lepidosteoids, predominate over
+all the other fishes: _Lepidotus_, _Semionotus_, _Pholidophorus_,
+_Pachycormus_, _Eugnathus_, _Tetragonolepis_, are represented by
+numerous species; other remarkable genera are _Aspidorhynchus_,
+_Belonostomus_, _Saurostomus_, _Sauropsis_, _Thrissonotus_, _Conodus_,
+_Ptycholepis_, _Endactis_, _Centrolepis_, _Legnonotus_, _Oxygnathus_,
+_Heterolepidotus_, _Isocolum_, _Osteorhachis_, _Mesodon_. These genera
+offer evidence of a great change since the preceding period, the
+majority not being represented in older strata, whilst, on the other
+hand, many are continued into the succeeding oolithic formations. The
+homocercal termination of the vertebral column commences to supersede
+the heterocercal, and many of the genera have well ossified and
+distinctly segmented spinal columns. Also the cycloid form of scales
+becomes more common: one genus (_Leptolepis_) being, with regard to
+the preserved hard portions of its organisation, so similar to the
+Teleosteous type that some Palæontologists refer it (with much reason)
+to that sub-class.
+
+   [See _E. Sauvage_, Essai sur la Faune Ichthyologique de la
+   période Liasique. In “Bibl. de l’école des hautes études,” xiii.
+   art. 5. Paris 1875. 8^o.]
+
+As already mentioned, the _Oolithic_ formations show a great similarity
+of their fish-fauna to that of the Lias; but still more apparent is
+its approach to the existing fauna. Teeth have been found which cannot
+even generically be distinguished from _Notidanus_. The Rays are
+represented by genera like _Spathobatis_, _Belemnobatis_, _Thaumas_;
+the _Holocephali_ are more numerous than in the Lias (_Ischyodus_,
+_Ganodus_). The most common Ganoid genera are _Caturus_, _Pycnodus_,
+_Pholidophorus_, _Lepidotus_, _Leptolepis_, all of which had been more
+or less fully represented in the Lias. Also _Ceratodus_ is continued
+into it.
+
+       *       *       *       *       *
+
+The _Cretaceous_ group offers clear evidence of the further advance
+towards the existing fauna. Teeth of Sharks of existing genera
+_Carcharias_ (_Corax_), _Scyllium_, _Notidanus_, and _Galeocerdo_, are
+common in some of the marine strata, whilst Hybodonts and Cestracionts
+are represented by a small number of species only; of the latter one
+new genus, _Ptychodus_, appears and disappears. A very characteristic
+Ganoid genus, _Macropoma_, comprises homocercal fishes with rounded
+ganoid scales sculptured externally and pierced by prominent mucous
+tubes. _Caturus_ becomes extinct. Teeth and scales of _Lepidotus_
+(with _Sphærodus_ as subgenus), clearly a freshwater fish, are widely
+distributed in the Wealden, and finally disappear in the chalk; its
+body was covered with large rhomboidal ganoid scales. _Gyrodus_
+and _Aspidorhynchus_ occur in the beds of Voirons, _Coelodus_ and
+_Amiopsis_ (allied to Amra), in those of Comen, in Istria. But the
+Palæichthyes are now in the minority; undoubted Teleosteans have
+appeared, for the first time, on the stage of life in numerous genera,
+many of which are identical with still existing fishes. The majority
+are Acanthopterygians, but Physostomes and Plectognaths are likewise
+well represented, most of them being marine. Of Acanthopterygian
+families the first to appear are the _Berycidæ_, represented by
+several very distinct genera: _Beryx_; _Pseudoberyx_ with abdominal
+ventral fins; _Berycopsis_ with cycloid scales; _Homonotus_,
+_Stenostoma_, _Sphenocephalus_, _Acanus_, _Hoplopteryx_, _Platycornus_
+with granular scales; _Podocys_ with a dorsal extending to the neck;
+_Acrogaster_, _Macrolepis_, _Rhacolepis_ from the chalk of Brazil.
+The position of _Pycnosterynx_ is uncertain, it approaches certain
+Pharyngognaths. True _Percidæ_ are absent, whilst the _Carangidæ_,
+_Sphyrænidæ_, _Cataphracti_, _Gobiidæ_, _Cottidæ_, and _Sparidæ_
+are represented by one or more genera. Somewhat less diversified
+are the Physostomes, which belong principally to the _Clupeidæ_ and
+_Dercetidæ_, most of the genera being extinct; Clupea is abundant in
+some localities. _Scopelidæ_ (_Hemisaurida_ and _Saurocephalus_) occur
+in the chalk of Comen in Istria, and of Mæstricht. Of all cretaceous
+deposits none surpass those of the Lebanon with regard to the number of
+genera, species, and individuals; the forms are exclusively marine, and
+the remains in the most perfect condition.
+
+       *       *       *       *       *
+
+In the _Tertiary_ epoch the Teleosteans have almost entirely replaced
+the Ganoids; a few species only of the latter make their appearance,
+and they belong to existing genera, or, at least, very closely
+allied forms (_Lepidosteus_, _Amia_, _Hypamia_, _Acipenser_). The
+Chondropterygians merge more and more into recent forms; Holocephali
+continue, and still are better represented than in the present fauna.
+The Teleosteans show even in the Eocene a large proportion of existing
+genera, and the fauna of some localities of the Miocene (Oeningen)
+is almost wholly composed of them. On the whole, hitherto more than
+one-half have been found to belong to existing genera, and there is
+no doubt that the number of seemingly distinct extinct genera will be
+lessened as the fossils will be examined with a better knowledge of
+the living forms. The distribution of the fishes differed widely from
+that of our period, many of our tropical genera occurring in localities
+which are now included within our temperate zone, and being mixed with
+others, which nowadays are restricted to a colder climate: a mixture
+which continues throughout the Pliocene.
+
+       *       *       *       *       *
+
+A few families of fishes, like the freshwater Salmonidæ, seem to have
+put in their appearance in _Post-pliocene_ times; however, not much
+attention has been paid to fish-remains of these deposits; and such as
+have been incidentally examined offer evidence of the fact that the
+distribution of fishes has not undergone any further essential change
+down to the present period.
+
+   [See _E. Sauvage_, Mémoire sur la Faune Ichthyologique de
+   la période Tertiaire. Paris 1873. 8°.]
+
+  [Illustration: Fig. 102.--_Pycnodus rhombus_, a Ganoid from
+  the Upper Oolite.]
+
+
+
+
+                             CHAPTER XVI.
+
+         THE DISTRIBUTION OF EXISTING FISHES OVER THE EARTH’S
+                       SURFACE--GENERAL REMARKS.
+
+
+In an account of the geographical distribution of fishes the
+_Freshwater_ forms are to be kept separate from the _Marine_. However,
+when we attempt to draw a line between these two kinds of fishes, we
+meet with a great number of species and of facts which would seem to
+render that distinction very vague. There are not only species which
+can gradually accommodate themselves to a sojourn in either salt or
+fresh water, but there are also such as seem to be quite indifferent to
+a rapid change from one into the other: so that individuals of one and
+the same species (Gastrosteus, Gobius, Blennius, Osmerus, Retropinna,
+Clupea, Syngnathus, etc.), may be found at some distance out at sea,
+whilst others live in rivers far beyond the influence of the tide, or
+even in inland fresh waters without outlet to the sea. The majority of
+these fishes belong to forms of the fauna of the _brackish_ water, and
+as they are not an insignificant portion of the fauna of almost every
+coast, we shall have to treat of them in a separate chapter.
+
+Almost every large river offers instances of truly marine fishes (such
+as _Serranus_, _Sciænidæ_, _Pleuronectes_, _Clupeidæ_, _Tetrodon_,
+_Carcharias_, _Trygonidæ_), ascending for hundreds of miles of their
+course; and not periodically, or from any apparent physiological
+necessity, but sporadically throughout the year, just like the
+various kinds of marine Porpoises which are found all along the
+lower course of the Ganges, Yang-tseKiang, the Amazons, the Congo,
+etc. This is evidently the commencement of a change in a fish’s
+habits, and, indeed, not a few of such fishes have actually taken up
+their permanent residence in fresh waters (as species of Ambassis,
+Apogon Dules, Therapon, Sciæna, Blennius, Gobius, Atherina, Mugil,
+Myxus, Hemirhamphus, Clupea, Anguilla, Tetrodon, Trygon): all forms
+_originally marine_.
+
+On the other hand, we find fishes belonging to freshwater genera
+descending rivers and sojourning in the sea for a more or less limited
+period; but these instances are much less in number than those in which
+the reverse obtains. We may mention species of _Salmo_ (the Common
+Trout, the Northern Charr), and Siluroids (as _Arius_, _Plotosus_).
+_Coregonus_, a genus so characteristic of the inland lakes of Europe,
+Northern Asia, and North America, nevertheless offers some instances
+of species wandering by the effluents into the sea, and taking up
+their residence in salt water, apparently by preference, as _Coregonus
+oxyrhynchus_. But of all the Freshwater families none exhibit so great
+a capability of surviving the change from fresh into salt water, as
+the _Gastrosteidæ_ (Sticklebacks), of the northern Hemisphere, and the
+equally diminutive _Cyprinodontidæ_ of the tropics; not only do they
+enter into, and live freely in, the sea, but many species of the latter
+family inhabit inland waters, which, not having an outlet, have become
+briny, or impregnated with a larger proportion of salts than pure sea
+water. During the voyage of the “Challenger” a species of _Fundulus_,
+_F. nigrofasciatus_, which inhabits the fresh and brackish waters of
+the Atlantic States of North America, was obtained, with Scopelids and
+other pelagic forms, in the tow-net, midway between St. Thomas and
+Teneriffe.
+
+Some fishes annually or periodically ascend rivers for the purpose of
+spawning, passing the rest of the year in the sea, as Sturgeons, many
+Salmonoids, some Clupeoids, Lampreys, etc. The two former evidently
+belonged originally to the freshwater series, and it was only in the
+course of their existence that they acquired the habit of descending
+to the sea, perhaps because their freshwater home did not offer a
+sufficient supply of food. These migrations of freshwater fishes have
+been compared with the migrations of birds; but they are much more
+limited in extent, and do not impart an additional element to the fauna
+of the place to which they migrate, as is the case with the distant
+countries to which birds migrate.
+
+The distinction between freshwater and marine fishes is further
+obscured by geological changes, in consequence of which the salt
+water is gradually being changed into fresh, or _vice versa_. These
+changes are so gradual and spread over so long a time, that many of
+the fishes inhabiting such localities accommodate themselves to the
+new conditions. One of the most remarkable and best studied instances
+of such an alteration is the Baltic, which, during the second half
+of the Glacial period, was in open and wide communication with the
+Arctic Ocean, and evidently had the same marine fauna as the White
+Sea. Since then, by the rising of the land of Northern Scandinavia
+and Finland, this great gulf of the Arctic Ocean has become an inland
+sea, with a narrow outlet into the North Sea, and its water, in
+consequence of the excess of the fresh water pouring into it over the
+loss by evaporation, has been so much diluted as to be nearly fresh
+at its northern extremities: and yet nine species, the origin of
+which from the Arctic Ocean can be proved, have survived the changes,
+propagating their species, agreeing with their brethren in the Arctic
+Ocean in every point, but remaining comparatively smaller. On the other
+hand, fishes which we must regard as true freshwater fishes, like
+the Rudd, Roach, Pike, Perch, enter freely the brackish water of the
+Baltic.[17] Instances of marine fishes being permanently retained in
+fresh water in consequence of geological changes are well known: thus
+_Cottus quadricornis_ in the large lakes of Scandinavia; species of
+_Gobius_, _Blennius_, and _Atherina_ in the lakes of Northern Italy;
+_Comephorus_, of the depths of the Lake of Baikal, which seems to be
+a dwarfed Gadoid. _Carcharias gangeticus_ in inland lakes of the Fiji
+Islands, is another instance of a marine fish which has permanently
+established itself in fresh water.
+
+In the miocene formation of Licata in Sicily, in which fish remains
+abound, numerous Cyprinoids are mixed with littoral and pelagic
+forms. Sauvage found in 450 specimens from that locality, not less
+than 266, which were Leucisci, Alburni, or Rhodei. Now, although it
+is quite possible that in consequence of a sudden catastrophe the
+bodies of those Cyprinoids were carried by a freshwater current into,
+and deposited on the bottom of, the sea, the surmise that they lived
+together with the littoral fishes in the brackish water of a large
+estuary, which was not rarely entered by pelagic forms, is equally
+admissible. And, if confirmed by other similar observations, this
+instance of a mixture of forms which are now strictly freshwater or
+marine, may have an important bearing on the question to what extent
+fishes have in time changed their original habitat.
+
+Thus there is a constant exchange of species in progress between the
+freshwater and marine faunæ, and in not a few cases it would seem
+almost arbitrary to refer a genus or even larger group of fishes
+to one or the other; yet there are certain groups of fishes which
+entirely, or with but few exceptions are, and, apparently, during
+the whole period of their existence have been, inhabitants either of
+the sea or of fresh water; and as the agencies operating upon the
+distribution of marine fishes differ greatly from those influencing
+the dispersal of freshwater fishes, the two series must be treated
+separately. The most obvious fact that dry land, which intervenes
+between river systems, offers to the rapid spreading of a freshwater
+fish an obstacle which can be surmounted only exceptionally or by a
+most circuitous route, whilst marine fishes may readily and voluntarily
+extend their original limits, could be illustrated by a great number
+of instances. Without entering into details, it may suffice to state
+as the general result, that no species or genus of freshwater fishes
+has anything like the immense range of the corresponding categories
+of marine fishes; and that, with the exception of the Siluroids,
+no other freshwater family is so widely spread as the families of
+marine fishes. Surface temperature or climate which is, if not the
+most, one of the most important physical factors in the limitation
+of freshwater fishes, similarly affects the distribution of marine
+fishes, but in a less degree, and only those which live near to the
+shore or the surface of the ocean; whilst it ceases to exercise its
+influence in proportion to the depth, the true deep-sea forms being
+entirely exempt from its operation. Light, which is pretty equally
+distributed over the localities inhabited by freshwater fishes, cannot
+be considered as an important factor in their distribution, but it
+contributes towards constituting the impassable barrier between the
+surface and abyssal forms of marine fishes. Altitude has stamped the
+fishes of the various Alpine provinces of the globe with a certain
+character, and limited their distribution; but the number of these
+Alpine forms is comparatively small, ichthyic life being extinguished
+at great elevations even before the mean temperature equals that of the
+high latitudes of the Arctic region, in which some freshwater fishes
+flourish. On the other hand, the depths of the ocean, far exceeding the
+altitude of the highest mountains, still swarm with forms specially
+adapted for abyssal life. That other physical conditions of minor and
+local importance, under which fresh water fishes live, and by which
+their dispersal is regulated, are more complicated than similar ones
+of the ocean, is probable, though perhaps less so than is generally
+supposed: for the fact is that the former are more accessible to
+observation than the latter, and are, therefore, more generally and
+more readily comprehended and acknowledged. Thus, not only because many
+of the most characteristic forms of the marine and freshwater series
+are found, on taking a broader view of the subject, to be sufficiently
+distinct, but also because their distribution depends on causes
+different in their nature as well as the degree of their action, it
+will be necessary to treat of the two series separately. Whether the
+oceanic areas correspond in any way to the terrestrial will be seen in
+the sequel.
+
+  [Illustration: Fig. 103.--Ganoid scales of _Tetragonolepis_.]
+
+
+
+
+                             CHAPTER XVII.
+
+                THE DISTRIBUTION OF FRESHWATER FISHES.
+
+
+Having shown above that numerous marine fishes enter fresh waters, and
+that some of them have permanently established themselves therein,
+we have to eliminate from the category of freshwater fishes all such
+adventitious elements. They are derived from forms, the distribution
+of which is regulated by other agencies, and which, therefore, would
+obscure the relations of the faunæ of terrestrial regions if they were
+included in them. They will be mentioned with greater propriety along
+with the fishes constituting the fauna of the brackish water.
+
+True freshwater fishes are the following families and groups only:--
+
+    Dipnoi                with 4 species.
+    Acipenseridæ and
+      Polyodontidæ         „  26   „
+    Amiidæ                 „   1   „
+    Polypteridæ.           „   2   „
+    Lepidosteidæ.          „   3   „
+    Percina                „  46   „
+    Grystina               „  11   „
+    Aphredoderidæ          „   1   „
+    Centrarchina           „  26   „
+    Dules                  „  10   „
+    Nandidæ                „   7   „
+    Polycentridæ           „   3   „
+    Labyrinthici           „  30   „
+    Luciocephalidæ         „   1   „
+    Gastrosteus            „  10   „
+    Ophiocephalidæ         „  31   „
+    Mastacembelidaæ        „  13   „
+    Chromides              „ 105   „
+    Comephoridæ            „   1   „
+    Gadopsidæ              „   1   „
+    Siluridæ               „ 572   „
+    Characinidæ            „ 261   „
+    Haplochitonidæ         „   3   „
+    Salmonidæ (3 genera
+      excepted)            „ 135   „
+    Percopsidæ             „   1   „
+    Galaxiidæ              „  15   „
+    Mormyridæ (and
+      Gymnarchidæ)         „  52   „
+    Esocidæ                „   8   „
+    Umbridæ                „   2   „
+    Cyprinodontidæ         „ 112   „
+    Heteropygii            „   2   „
+    Cyprinidæ              „ 724   „
+    Kneriidæ               „   2   „
+    Hyodontidæ             „   1   „
+    Osteoglossidæ          „   5   „
+    Notopteridæ            „   5   „
+    Gymnotidæ              „  20   „
+    Symbranchidæ           „   5   „
+    Petromyzontidæ         „  12   „
+                           --------------
+                     Total  2269 species.
+                           ==============
+
+As in every other class of animals, these freshwater genera and
+families vary greatly with regard to the extent of their geographical
+range; some extend over the greater half of the continental areas,
+whilst others are limited to one continent only, or even to a very
+small portion of it. As a general rule, a genus or family of freshwater
+fishes is regularly dispersed and most developed within a certain
+district, the species and individuals becoming scarcer towards the
+periphery as the type recedes more from its central home, some outposts
+being frequently pushed far beyond the outskirts of the area occupied
+by it. But there are not wanting those remarkable instances of closely
+allied forms occurring, almost isolated, at most distant points,
+without being connected by allied species in the intervening space;
+or of members of the same family, genus, or species inhabiting the
+opposite shores of an ocean, and separated by many degrees of abyssal
+depths. We mention of a multitude of such instances the following
+only:--
+
+
+_A_. Species identical in distant continents--
+
+1. A number of species inhabiting Europe and the temperate parts of
+eastern North America, as _Perca fluviatilis_, _Gastrosteus pungitius_,
+_Lota vulgaris_, _Salmo solar_, _Esox lucius_, _Acipenser sturio_,
+_Acipenser maculosus_, and several Petromyzonts.
+
+2. _Lates calcarifer_ is common in India as well as in Queensland.
+
+3. _Galaxias attenuatus_ inhabits Tasmania, New Zealand, the Falkland
+Islands, and the southernmost part of the South American continent.
+
+4. Several Petromyzonts enter the fresh waters of Tasmania, South
+Australia, New Zealand, and Chili.
+
+
+_B._ Genera identical in distant continents--
+
+1. The genus _Umbra_, so peculiar a form as to be the type of a
+distinct family consisting of two most closely allied species only, one
+of which is found in the Atlantic States of North America, the other in
+the system of the Danube.
+
+2. A very distinct genus of Sturgeons, _Scaphirhynchus_, consisting
+of two species only, one inhabiting fresh waters of Central Asia, the
+other the system of the Mississippi.
+
+3. A second most peculiar genus of Sturgeons, _Polyodon_, consists
+likewise of two species only, one inhabiting the Mississippi, the other
+the Yang-tse-kiang.
+
+4. _Amiurus_, a Siluroid, and _Catostomus_, a Cyprinoid genus, both
+well represented in North America, occur in a single species in
+temperate China.
+
+5. _Lepidosiren_ is represented by one species in tropical America, and
+by the second in tropical Africa (_Protopterus_).
+
+6. _Notopterus_ consists of three Indian and two West African species.
+
+7. _Mastacembelus_ and _Ophiocephalus_, genera characteristic of the
+Indian region, emerge severally by a single species in West and Central
+Africa.
+
+8. _Symbranchus_ has two Indian and one South American species.
+
+9. _Prototroctes_, the singular antarctic analogue of _Coregonus_,
+consists of two species, one in the south of Australia the other in New
+Zealand.
+
+10. _Galaxias_ is equally represented in Southern Australia, New
+Zealand, and the southern parts of South America.
+
+
+_C._ Families identical in distant continents--
+
+1. The _Labyrinthici_, represented in Africa by 5, and in India by
+25 species.
+
+2. The _Chromides_, represented in Africa by 25, and in South
+America by 80 species.
+
+3. The _Characinidæ_, represented in Africa by 35, and in South
+America by 226 species.
+
+4. The _Haplochitonidæ_, represented in Southern Australia by one,
+in New Zealand by one, and in Patagonia by a third species.
+
+This list could be much increased from the families of _Siluridæ_
+and _Cyprinidæ_, but as these have a greater range than the other
+Freshwater fishes, they do not illustrate with equal force the object
+for which the list has been composed.
+
+       *       *       *       *       *
+
+The ways in which the dispersal of Freshwater fishes has been effected
+were various; they are probably all still in operation, but most work
+so slowly and imperceptibly as to escape direct observation; perhaps,
+they will be more conspicuous, after science and scientific inquiry
+shall have reached to a somewhat greater age. From the great number
+of freshwater forms which we see at this present day acclimatised in,
+gradually acclimatising themselves in, or periodically or sporadically
+migrating into, the sea, we must conclude that, under certain
+circumstances, salt water may cease to be an impassable barrier at some
+period of the existence of freshwater species, and that many of them
+have passed from one river through salt water into another. Secondly,
+the headwaters of some of the grandest rivers, the mouths of which are
+at opposite ends of the continents which they drain, are sometimes
+distant from each other a few miles only; the intervening space may
+have been easily bridged over for the passage of fishes by a slight
+geological change affecting the level of the watershed, or even by
+temporary floods; and a communication of this kind, if existing for a
+limited period only, would afford the ready means of an exchange of
+a number of species previously peculiar to one or the other of those
+river or lake systems. Some fishes, provided with gill-openings so
+narrow that the water moistening the gills cannot readily evaporate;
+and endowed, besides, with an extraordinary degree of vitality, like
+many Siluroids (_Clarias_, _Callichthys_), Eels, etc., are enabled to
+wander for some distance over land, and may thus reach a water-course
+leading them thousands of miles from their original home. Finally,
+fishes or their ova may be accidentally carried by waterspouts, by
+aquatic birds or insects, to considerable distances.
+
+Freshwater fishes of the present fauna were already in existence when
+the great changes of the distribution of land and water took place
+in the tertiary epoch; and having stated that salt water is not an
+absolute barrier to the spreading of Freshwater fishes, we can now
+more easily account for those instances of singular disconnection of
+certain families or genera. It is not necessary to assume that there
+was a continuity of land stretching from the present coast of Africa
+to South America, or from South America to New Zealand and Australia,
+to explain the presence of identical forms at so distant localities;
+it suffices to assume that the distances were lessened by intervening
+archipelagoes, or that an oscillation has taken place in the level of
+the land area.
+
+Dispersal of a type over several distant continental areas may be
+evidence of its great antiquity, but it does not prove that it is of
+greater antiquity than another limited to one region only. Geological
+evidence is the only proof of the antiquity of a type. Thus, although
+the _Dipnoi_ occur on the continents of Africa, South America, and
+Australia, and their present distribution is evidently the consequence
+of their wide range in palæozoic and secondary epochs; the proof
+of their high antiquity can be found in their fossil remains only.
+For, though the Siluroids have a still greater range, their wide
+distribution is of comparatively recent date, as the few fossil remains
+that have been found belong to the tertiary epoch. The rapidity of
+dispersal of a type depends entirely on its facility to accommodate
+itself to a variety of physical conditions, and on the degree of
+vitality by which it is enabled to survive more or less sudden changes
+under unfavourable conditions; proof of this is afforded by the family
+of Siluroids, many of which can suspend for some time the energy of
+their respiratory functions, and readily survive a change of water.
+
+       *       *       *       *       *
+
+To trace the geological sequence of the distribution of an ichthyic
+type, and to recognise the various laws which have governed, and
+are still governing its dispersal, is one of the ultimate tasks of
+Ichthyology. But the endeavour to establish by means of our present
+fragmentary geological knowledge the divisions of the fauna of the
+globe, leads us into a maze of conflicting evidence; or, as Mr.
+Wallace truly observes, “any attempt to exhibit the regions of former
+geological ages in combination with those of our own period must lead
+to confusion.” Nevertheless, as the different types of animals found
+at the present day within a particular area have made their appearance
+therein at distant periods, we should endeavour to decide as far as
+we can, in an account of the several zoo-geographical divisions, the
+following questions:--
+
+1. Which of the fishes of an area should be considered to be the
+remnants of _ancient_ types, probably spread over much larger areas in
+preceding epochs?
+
+2. Which of them are to be considered to be _autochthont_ species,
+that is, forms which came in the tertiary epoch or later into existence
+within the area to which they are still limited, or from which they
+have since spread?
+
+3. Which are the forms which must be considered to be _immigrants_
+from some other region?
+
+The mode of division of the earth’s surface into zoological regions
+or areas now generally adopted, is that proposed by Mr. Sclater,
+which recommends itself as most nearly agreeing with the geographical
+divisions. These regions are as follows:--
+
+   I. PALÆOGÆA.
+
+      1. The _Palæarctic_ region; including Europe, temperate Asia,
+           and North Africa.
+
+      2. The _Ethiopian_ region; including Africa, south of the
+           Sahara, Madagascar, and the Mascarene Islands; also
+           Southern Arabia.
+
+      3. The _Indian_ region; including India south of the
+           Himalayas, to Southern China, Borneo, and Java.
+
+      4. The _Australian_ region; including Australia, the
+           Pacific Islands, Celebes, and Lombock.
+
+   II. NEOGÆA.
+
+      5. The _Nearctic_ region; including North America to
+           Northern Mexico.
+
+      6. The _Neotropical_ region; including South America, the West
+           Indies, and Southern Mexico.
+
+Comparatively few classes and orders of animals have been carefully
+studied with regard to their geographical distribution, but the
+majority of those which have been examined show that the difference
+of latitude is accompanied by a greater dissimilarity of indigenous
+species than that of longitude, and that a main division into an old
+world and new world fauna is untenable. More especially the Freshwater
+fishes, with which we are here solely concerned, have been spread in
+_circumpolar_ zones, and in a but limited degree from north to
+south. No family, much less a genus, ranges from the north to the
+south, whilst a number of families and genera make the entire circuit,
+and some species more than half of the circuit round the globe within
+the zone to which they belong. Not even the Cyprinoids and Siluroids,
+which are most characteristic of the freshwater fauna of our period,
+are an exception to this. Temperature and climate, indeed, are the
+principal factors by which the character of the freshwater fauna is
+determined; they form the barriers which interfere with the unlimited
+dispersal of an ichthyic type, much more than mountain ranges, deserts,
+or oceans. Hence the tropical zone is an impassable barrier to the
+northern Freshwater fish in its progress towards the south; where
+a similarly temperate climate obtains in the southern hemisphere,
+fish-forms appear _analogous_ to those of the north, but
+_genetically_ and _structurally distinct_.
+
+The similarity which obtains in fishes at somewhat distant points
+of the same degree of longitude, rarely extends far, and is due to
+the natural tendency of every animal to spread as far as physical
+conditions will permit. Between two regions situated north and south
+of each other there is always a debateable border ground, in parts of
+which sometimes the fishes of the one, sometimes those of the other,
+predominate, and which is, in fact, a _band_ of demarcation. Within
+this band the regions overlap each other; therefore, their border
+_lines_ are rarely identical, and should be determined by the northern
+and southernmost extent of the most characteristic types of each
+region. Thus, for instance, in China, a broad band intervenes between
+temperate and tropical Asia, in which these two faunæ mix, and the
+actual northern border line of the tropical fauna is north of the
+southern border line of temperate Asia.
+
+It is the aim of every philosophical classification to indicate the
+degree of affinity which obtains between the various divisions; but
+the mode of division into six equivalent regions, as given above, does
+not fulfil this aim with regard to Freshwater fishes, the distribution
+of which allows of further generalisation and subdivision. The two
+families, _Cyprinidæ_ and _Siluridæ_, of which the former yields a
+contingent of one-third, and the latter of one-fourth of all the
+freshwater species known of our period, afford most valuable guidance
+for the valuation of the degrees of affinity between the various
+divisions. The Cyprinoids may be assumed to have taken their origin
+in the Alpine region, dividing the temperate and tropical parts of
+Asia; endowed with a greater capability of acclimatising themselves
+in a temperate as well as tropical climate than any other family of
+freshwater fishes, they spread north and south as well as east and
+west; in the preglacial epoch they reached North America, but they have
+not had time to penetrate into South America, Australia, or the islands
+of the Pacific. The Siluroids, principally fishes of the sluggish
+waters of the plains, and well adapted for surviving changes of the
+water in which they live, for living in mud or sea-water, flourish
+most in the tropical climate, in which this type evidently had its
+origin. They came into existence after the Cyprinoids, fossil remains
+being known only from tertiary deposits in India, none from Europe.
+They rapidly spread over the areas of land within the tropical zone,
+reaching northern Australia from India, and one species even immigrated
+into the Sandwich Islands, probably from South America. The Coral
+Islands of the Pacific still remain untenanted by them. Their progress
+into temperate regions was evidently slow, only very few species
+penetrating into the temperate parts of Asia and Europe; and the North
+American species, although more numerous, showing no great variety
+of structure, all belonging to the same group (_Amiurina_). Towards
+the south their progress was still slower, Tasmania, New Zealand, and
+Patagonia being without representatives, whilst the streams of the
+Andes of Chili are inhabited by a few dwarfed forms identical with such
+as are characteristic of similar localities in the more northern and
+warmer parts of the South American continent.
+
+After these preliminary remarks we propose the following division of
+the fauna of Freshwater fishes:--
+
+I. THE NORTHERN ZONE.--Characterised by Acipenseridæ. Few
+     Siluridæ. Numerous Cyprinidæ. Salmonidæ, Esocidæ.
+
+   1. _Europo-Asiatic or Palæarctic Region_.--Characterised by
+        absence of osseous Ganoidei; Cobitidæ and Barbus numerous.
+
+   2. _North American Region_.--Characterised by osseous Ganoidei,
+        Amiurina, and Catostomina; but no Cobitidæ or Barbus.
+
+II. THE EQUATORIAL ZONE.--Characterised by the development of
+      Siluridæ.
+
+   A. _Cyprinoid Division_.--Characterised by presence of Cyprinidæ
+        and Labyrinthici.
+
+     1. _Indian Region_.--Characterised by [absence of Dipnoi[18]]
+          Ophiocephalidæ, Mastacembelidæ. Cobitidæ numerous.
+
+     2. _African Region_.--Characterised by presence of Dipnoi and
+          Polypteridæ. Chromides and Characinidæ numerous. Mormyridæ.
+          Cobitidæ absent.
+
+   B. _Acyprinoid Division_.--Characterised by absence of Cyprinidæ
+        and Labyrinthici.
+
+     1. _Tropical American Region_.--Characterised by presence of
+          Dipnoi. Chromides and Characinidæ numerous. Gymnotidæ.
+
+     2. _Tropical Pacific Region_.--Characterised by presence of
+          Dipnoi. Chromides and Characinidæ absent.
+
+III. THE SOUTHERN ZONE.--Characterised by absence of Cyprinidæ, and
+       scarcity of Siluridæ. Haplochitonidæ and Galaxiidæ represent
+       the Salmonoids and Esoces of the Northern zone. One region
+       only.
+
+   1. _Antarctic Region_.--Characterised by the small number of
+        species; the fishes of--
+
+     _a_. The Tasmanian sub-region;
+     _b_. The New Zealand sub-region;
+     _c_. The Patagonian sub-region;
+
+being almost identical.[19]
+
+In the following detailed account we begin with a description of the
+equatorial zone, this being the one from which the two principal
+families of freshwater fishes seem to have spread.
+
+                          I. EQUATORIAL ZONE.
+
+Roughly speaking, the borders of this zoological zone coincide with
+the geographical limits of the tropical zone, the tropics of the
+Cancer and Capricorn; its characteristic forms, however, extend in
+undulating lines several degrees north and southwards. Commencing from
+the west coast of Africa the desert of the Sahara forms a well-marked
+boundary between the equatorial and northern zones; as the boundary
+approaches the Nile it makes a sudden sweep towards the north as far
+as Northern Syria (_Mastacembelus_, near Aleppo, and in the Tigris;
+_Clarias_ and _Chromides_, in the lake of Galilee); crosses through
+Persia and Afghanistan (_Ophiocephalus_), to the southern ranges of the
+Himalayas, and follows the course of the Yang-tse-Kiang, which receives
+its contingent of equatorial fishes through its southern tributaries.
+Its continuation through the North Pacific may be considered to be
+indicated by the tropic which strikes the coast of Mexico at the
+southern end of the Gulf of California. Equatorial types of South
+America are known to extend so far northwards; and by following the
+same line the West India Islands are naturally included in this zone.
+
+Towards the south the equatorial zone embraces the whole of Africa
+and Madagascar, and seems to extend still farther south in Australia,
+its boundary probably following the southern coast of that continent;
+the detailed distribution of the freshwater fishes of South-Western
+Australia has been but little studied, but the few facts which we
+know show that the tropical fishes of Queensland follow the principal
+water-course of that country, the Murray River, far towards the
+south and probably to its mouth. The boundary-line then stretches
+northwards of Tasmania and New Zealand, coinciding with the tropic
+until it strikes the western slope of the Andes, on the South American
+Continent, where it again bends southwards to embrace the system of the
+Rio de la Plata.
+
+The equatorial zone is divided into four regions:--
+
+    A. The Indian region.
+    B. The African region.
+    C. The Tropical American region.
+    D. The Tropical Pacific region.
+
+These four regions diverge into two well-marked divisions, one of
+which is characterised by the presence of Cyprinoid fishes, combined
+with the development of Labyrinthici; whilst in the other both these
+types are absent. The boundary between the Cyprinoid and Acyprinoid
+division seems to follow Wallace’s line, a line drawn from the south of
+the Philippines between Borneo and Celebes, and farther south between
+Bali and Lombock. Borneo abounds in Cyprinoids; from the Philippine
+Islands a few only are known at present, and in Bali two species have
+been found; but none are known from Celebes or Lombock, or from islands
+situated farther east of them.[20]
+
+Taking into consideration the manner in which Cyprinoids and Siluroids
+have been dispersed, we are obliged to place the Indian region as
+the first in the order of our treatment; and indeed the number of
+its freshwater fishes, which appear to have spread from it into the
+neighbouring regions, far exceeds that of the species which it has
+received from them.
+
+       *       *       *       *       *
+
+A. The INDIAN REGION comprises the whole continent of Asia south of
+the Himalayas and the Yang-tse-kiang; it includes the islands to
+the west of Wallace’s line. Towards the north-east the island of
+Formosa, which also by other parts of its fauna leans more towards the
+equatorial zone, has received some characteristic Japanese Freshwater
+fishes, for instance, the singular Salmonoid _Plecoglossus_. Within
+the geographical boundaries of China the Freshwater fishes of the
+tropics pass gradually into those of the northern zone, both being
+separated by a broad debateable ground. The affluents of the great
+river traversing this district are more numerous from the south than
+from the north, and carry the southern fishes far into the temperate
+zone. The boundary of this region towards the north-west is scarcely
+better defined. Before Persia passed through the geological changes
+by which its waters were converted into brine and finally dried
+up, it seems to have been inhabited by many characteristic Indian
+forms, of which a few still survive in the tract intervening between
+Afghanistan and Syria; _Ophiocephalus_ and _Discognathus_ have each
+at least one representative, _Macrones_ has survived in the Tigris,
+and Mastacembelus has penetrated as far as Aleppo. Thus, Freshwater
+fishes belonging to India, Africa, and Europe, are intermingled in a
+district which forms the connecting link between the three continents.
+Of the freshwater fishes of Arabia we are perfectly ignorant; so much
+only being known that the Indian _Discognathus lamta_ occurs in the
+reservoirs of Aden, having, moreover, found its way to the opposite
+African coast; and that the ubiquitous Cyprinodonts flourish in
+brackish pools of Northern Arabia.
+
+The following is the list of the forms of freshwater fishes inhabiting
+this region:[21]--
+
+    Percina--
+        Lates[22] [Africa, Australia]                1 species.
+    _Nandina_                                        7    „
+    Labyrinthici [Africa]                            25   „
+    _Luciocephalidæ_                                  1   „
+    _Ophiocephalidæ_ [1 species in Africa]           30   „
+    _Mastacembelidæ_ [3 species in Africa]           10   „
+    Chromides [Africa, South America]
+        _Etroplus_                                    2   „
+    Siluridæ--
+        Clariina [Africa]                            12   „
+        _Chacina_                                     3   „
+        Silurina [Africa, Palæarct.]                 72   „
+        Bagrina [Africa]                             50   „
+        Ariina [Africa, Australia, South America]    40   „
+        _Bagariina_                                  20   „
+        Rhinoglanina [Africa]                         1   „
+        Hypostomatina [South America]                 5   „
+    Cyprinodontidæ--
+        Carnivoræ [Palæarct., North America,
+        Africa, South America]
+          Haplochilus [Africa, South America,
+            North America, Japan]                     4   „
+    Cyprinidæ [Palæarct., N. America, Africa]--
+        Cyprinina [Palæarct., N. America, Africa]   190   „
+        _Rasborina_ [Africa, 1 species]              20   „
+        _Semiplotina_                                 4   „
+        Danionina [Africa]                           30   „
+        Abramidina [Palæarct., N. Amer., Africa]     30   „
+        _Homalopterina_                              10   „
+        Cobitidina [Palæarct.]                       50   „
+    Osteoglossidæ [Africa, Australia, S. America]     1   „
+    Notopteridæ [Africa]                              3   „
+    Symbranchidæ--
+        _Amphipnous_                                  1   „
+        _Monopterus_                                  1   „
+        Symbranchus [1 species in S. America]         2   „
+                                                    ------------
+                                                    625 species.
+                                                    ============
+
+In analysing this list we find that out of 39 families or groups of
+freshwater fishes 12 are represented in this region, and that 625
+species are known to occur in it; a number equal to two-sevenths of
+the entire number of freshwater fishes known. This large proportion
+is principally due to the development of numerous local forms of
+Siluroids and Cyprinoids, of which the former show a contingent
+of about 200, and the latter of about 330 species. The combined
+development of those two families, and their undue preponderance over
+the other freshwater types, is therefore the principal characteristic
+of the Indian region. The second important character of its fauna is
+the apparently total absence of Ganoid and Cyclostomous fishes. Every
+other region has representatives of either Ganoids or Cyclostomes,
+some of both. However, attention has been directed to the remarkable
+coincidence of the geographical distribution of the _Sirenidæ_
+and _Osteoglossidæ_, and as the latter family is represented in
+Sumatra and Borneo, it may be reasonably expected that a Dipnoous form
+will be found to accompany it. The distribution of the _Sirenidæ_
+and _Osteoglossidæ_ is as follows:--
+
+                 _Tropical America._
+
+    Lepidosiren paradoxa.   |  Osteoglossum bicirrhosum.
+                            |  Arapaima gigas.
+
+                 _Tropical Australia._
+
+    Ceratodus forsteri.     |  Osteoglossum leichardti.
+    Ceratodus miolepis.
+
+              _East Indian Archipelago._
+
+        ?                   |  Osteoglossum formosum.
+
+                 _Tropical Africa._
+
+    Protopterus annectens.  |  Heterotis niloticus.
+
+Not only are the corresponding species found within the same region,
+but also in the same river systems; and although such a connection
+may and must be partly due to a similarity of habit, yet the identity
+of this singular distribution is so striking that it can only be
+accounted for by assuming that the _Osteoglossidæ_ are one of the
+earliest Teleosteous types which have been contemporaries of and have
+accompanied the present Dipnoi since or even before the beginning of
+the tertiary epoch.
+
+Of the _autochthont_ freshwater fishes of the Indian region, some
+are still limited to it, viz., the _Nandina_, the _Luciocephalidæ_
+(of which one species only exists in the Archipelago), of Siluroids
+the _Chacina_ and _Bagariina_, of Cyprinoids the _Semiplotina_ and
+_Homalopterina_; others very nearly so, like the _Labyrinthici_,
+_Ophiocephalidæ_, _Mastacembelidæ_, of Siluroids the _Silurina_, of
+Cyprinoids the _Rasborina_ and _Danionina_, and _Symbranchidæ_.
+
+The regions with which the Indian has least similarity are the North
+American and Antarctic, as they are the most distant. Its affinity to
+the other regions is of a very different degree:--
+
+1. Its affinity to the Europo-Asiatic region is indicated almost solely
+by three groups of Cyprinoids, viz., the _Cyprinina_, _Abramidina_,
+and _Cobitidina_. The development of these groups north and south of
+the Himalayas is due to their common origin in the highlands of Asia;
+but the forms which descended into the tropical climate of the south
+are now so distinct from their northern brethren that most of them are
+referred to distinct genera. The genera which are still common to both
+regions are only the true Barbels (_Barbus_), a genus which, of all
+Cyprinoids, has the largest range over the old world, and of which some
+160 species have been described; and, secondly, the Mountain Barbels
+(_Schizothorax_, etc.), which, peculiar to the Alpine waters of Central
+Asia, descend a short distance only towards the tropical plains, but
+extend farther into rivers within the northern temperate districts. The
+origin and the laws of the distribution of the _Cobitidina_ appear to
+have been identical with those of _Barbus_, but they have not spread
+into Africa.
+
+If, in determining the degree of affinity between two regions, we take
+into consideration the extent in which an exchange has taken place of
+the faunæ originally peculiar to each, we must estimate that obtaining
+between the freshwater fishes of the Europo-Asiatic and Indian regions
+as very slight indeed.
+
+2. There exists a great affinity between the Indian and African
+regions; seventeen out of the twenty-six families or groups found in
+the former are represented by one or more species in Africa, and many
+of the African species are not even generically different from the
+Indian. As the majority of these groups have many more representatives
+in India than in Africa, we may reasonably assume that the African
+species have been derived from the Indian stock; but this is probably
+not the case with the Siluroid group of _Clariina_, which with regard
+to species is nearly equally distributed between the two regions,
+the African species being referable to three genera (_Clarias_,
+_Heterobranchus_, _Gymnallabes_, with the subgenus _Channallabes_),
+whilst the Indian species belong to two genera only, viz. _Clarias_
+and _Heterobranchus_. On the other hand, the Indian region has derived
+from Africa one freshwater form only, viz. _Etroplus_, a member of the
+family of _Chromides_, so well represented in tropical Africa and South
+America. _Etroplus_ inhabits Southern and Western India and Ceylon, and
+has its nearest ally in a Madegasse Freshwater fish, _Paretroplus_.
+Considering that other African Chromides have acclimatised themselves
+at the present day in saline water, we think it more probable that
+Etroplus should have found its way to India through the ocean than over
+the connecting land area; where, besides, it does not occur.
+
+3. A closer affinity between the Indian and Tropical American regions
+than is indicated by the character of the equatorial zone generally,
+does not exist. No genus of Freshwater fishes occurs in India and South
+America without being found in the intermediate African region, with
+two exceptions. Four small Indian Siluroids (_Sisor_, _Erethistes_,
+_Pseudecheneis_, and _Exostoma_) have been referred to the South
+American _Hypostomatina_; but it remains to be seen whether this
+combination is based upon a sufficient agreement of their internal
+structure, or whether it is not rather artificial. On the other hand,
+the occurrence and wide distribution in tropical America of a fish of
+the Indian family Symbranchidæ (_Symbranchus marmoratus_), which is
+not only congeneric with, but also most closely allied to, the Indian
+_Symbranchus bengalensis_, offers one of those extraordinary anomalies
+in the distribution of animals of which no satisfactory explanation can
+be given at present.
+
+4. The relation of the Indian region to the Tropical Pacific region
+consists only in its having contributed a few species to the poor fauna
+of the latter. This immigration must have taken place within a recent
+period, because some species now inhabit fresh waters of tropical
+Australia and the South Sea Islands without having in any way changed
+their specific characters, as _Lates calcarifer_, species of _Dules_,
+_Plotosus anguillaris_; others (species of _Arius_) are but little
+different from Indian congeners. All these fishes must have migrated
+by the sea; a supposition which is supported by what we know of their
+habits. We need not add that India has not received a single addition
+to its freshwater fish-fauna from the Pacific region.
+
+Before concluding these remarks on the Indian region, we must mention
+that peculiar genera of Cyprinoids and Siluroids inhabit the streams
+and lakes of its alpine ranges in the north. Some of them, like the
+Siluroid genera _Glyptosternum_, _Euglyptosternum_, _Pseudecheneis_,
+have a folded disk on the thorax between their horizontally spread
+pectoral fins; by means of this they adhere to stones at the bottom of
+the mountain torrents, and without it they would be swept away into
+the lower courses of the rivers. The Cyprinoid genera inhabiting
+similar localities, and the lakes into which the alpine rivers pass,
+such as _Oreinus_, _Schizothorax_, _Ptychobarbus_, _Schizopygopsis_,
+_Diptychus_, _Gymnocypris_, are distinguished by peculiarly enlarged
+scales near the vent, the physiological use of which has not yet been
+ascertained. These alpine genera extend far into the Europo-Asiatic
+region, where the climate is similar to that of their southern home.
+No observations have been made by which the altitudinal limits of fish
+life in the Himalayas can be fixed, but it is probable that it reaches
+the line of perpetual snow, as in the European Alps which are inhabited
+by Salmonoids. Griffith found an _Oreinus_ and a Loach, the former in
+abundance, in the Helmund at Gridun Dewar, altitude 10,500 feet; and
+another Loach at Kaloo at 11,000 feet.
+
+       *       *       *       *       *
+
+B. THE AFRICAN REGION comprises the whole of the African continent
+south of the Atlas and the Sahara. It might have been conjectured that
+the more temperate climate of its southern extremity would have been
+accompanied by a conspicuous difference of the fish-fauna. But this is
+not the case; the difference between the tropical and southern parts
+of Africa consists simply in the gradual disappearance of specifically
+tropical forms, whilst Siluroids, Cyprinoids, and even Labyrinthici
+penetrate to its southern coast; no new form has entered to impart
+to South Africa a character distinct from the central portion of the
+continent. In the north-east the African fauna passes the Isthmus of
+Suez and penetrates into Syria; the system of the Jordan presenting
+so many African types that it has to be included in a description of
+the African region as well as of the Europo-Asiatic. This river is
+inhabited by three species of _Chromis_, one of _Hemichromis_, and
+_Clarias macracanthus_, a common fish of the Upper Nile. This infusion
+of African forms cannot be accounted for by any one of those accidental
+means of dispersal, as _Hemichromis_ is not represented in the
+north-eastern parts of Africa proper, but chiefly on the west coast and
+in the Central African lakes.
+
+Madagascar clearly belongs to this region. Besides some Gobies and
+_Dules_, which are not true freshwater fishes, four _Chromides_ are
+known. To judge from general accounts, its Freshwater fauna is poorer
+than might be expected; but, singular as it may appear, collectors
+have hitherto paid but little attention to the Freshwater fishes of
+this island. The fishes found in the freshwaters of the Seychelles
+and Mascarenes are brackish-water fishes, such as _Fundulus_,
+_Haplochilus_, _Elops_, _Mugil_, etc.
+
+The following is the list of the forms of Freshwater fishes inhabiting
+this region:--
+
+    Dipnoi [Australia, Neotrop.]--
+      _Lepidosiren annectens_                              1 species.
+
+    _Polypteridæ_                                          2    „
+
+    Percina (Cosmopol.)--
+      Lates [India, Australia]                             1    „
+    Labyrinthici [India]                                   5    „
+    Ophiocephalidæ [India]                                 1    „
+    Mastacembelidæ [India]                                 3    „
+
+    Chromides [South America]--
+      _Chromis_                                           23    „
+      _Hemichromis_                                        5    „
+      _Paretroplus_                                        1    „
+
+    Siluridæ--
+      Clariina [India]                                    14    „
+      Silurina [India, Palæarct.]                         11    „
+      Bagrina [India]                                     10    „
+      Pimelodina [South America]                           2    „
+      Ariina[23] [India, Australia, S. Amer., Patagonia]   4    „
+      Doradina [South America]--
+        _Synodontis_                                      15    „
+      Rhinoglanina [India]                                 2    „
+      _Malapterurina_                                      3    „
+
+    Characinidæ [South America]--
+      _Citharinina_                                        2    „
+      _Nannocharacina_                                     2    „
+      Tetragonopterina--
+        _Alestes_                                         14    „
+      Crenuchina--
+        _Xenocharax_                                       1    „
+      Hydrocyonina--
+        _Hydrocyon_                                        4    „
+      _Distichodontina_                                   10    „
+      _Ichthyborina_                                       2    „
+
+    _Mormyridæ_ (_Gymnarchidæ_)                           51    „
+
+    Cyprinodontidæ--
+      Carnivoræ [Palæarct., India, S. America--
+        Haplochilus [India, South America]                 7    „
+        Fundulus [Palæarct., Nearct.]                      1    „
+
+    Cyprinidæ [Palæarct., India, North America]--
+      Cyprinina [Palæarct., India, N. America--
+        Labeo [India]                                      6    „
+        Barynotus [India]                                  2    „
+        _Abrostomus_                                       2    „
+        Discognathus lamta[24] [India]                     1    „
+        Barbus [Palæarct., India]                         35    „
+      Rasborina [India]                                    1    „
+      Danionina [India]--
+        Barilius [India]                                   3    „
+      Abramidina [Palæarct., India, N. America]--
+        _Pelotrophus_                                      2    „
+
+    _Kneriidæ_                                             2    „
+
+    Osteoglossidæ [India, Australia, South America]--
+      _Heterotis_                                          1    „
+
+    _Pantodontidæ_                                         1    „
+
+    Notopteridæ [India]                                    2    „
+                                                          ------------
+                                                          255 species.
+                                                          ============
+
+Out of the 39 families or groups of freshwater fishes 15 are
+represented in the African region, or three more than in the Indian
+region; however of two of them, viz., the _Ophiocephalidæ_ and
+_Mastacembelidæ_, a few species only have found their way into
+Africa. On the other hand, the number of species is much less, viz.
+255, which is only two-fifths of that of the known Indian species. The
+small degree of specialisation and localisation is principally due to
+the greater uniformity of the physical conditions of this continent,
+and to the almost perfect continuity of the great river systems,
+which take their origin from the lakes in its centre. This is best
+shown by a comparison of the fauna of the Upper Nile with that of the
+West African rivers. The number of species known from the Upper Nile
+amounts to 56, and of these not less than 25 are absolutely identical
+with West African species. There is an uninterrupted continuity of the
+fish-fauna from west to the north-east, and the species known to be
+common to both extremities may be reasonably assumed to inhabit also
+the great reservoirs of water in the centre of the continent. A greater
+dissimilarity is noticeable between the west and north-east fauna
+on the one hand, and that of the Zambezi on the other; the affinity
+between them is merely generic; and all the fishes hitherto collected
+in Lake Nyassa have proved to be distinct from those of the Nile, and
+even from those of other parts of the system of the Zambezi.
+
+Africa, unlike India, does not possess either alpine ranges or outlying
+archipelagoes, the fresh waters of which would swell the number of its
+indigenous species; but at a future time, when its fauna is better
+known than at present, it is possible that the great difference in the
+number of species between this and the Indian regions may be somewhat
+lessened.
+
+The most numerously-represented families are the Siluroids, with
+61 species; the Cyprinoids, with 52; the Mormyridæ, with 51; the
+Characinidæ, with 35; and the Chromides, with 29. There is not,
+therefore, that great preponderance of the two first families over the
+remaining, which we noticed in the Indian region; in Africa there is a
+comparatively greater variety of distinct Freshwater types, imparting
+to the study of its fauna an unflagging pleasure such as is scarcely
+gained by the study of the other region. With the forms peculiar to it
+there are combined those of India as well as South America.
+
+In Tropical Africa there are still remnants of Ganoids: _Protopterus_
+(_Lepidosiren_) _annectens_ and _Polypterus bichir_, with the
+singularly modified _Calamoichthys_. The two former range from east to
+west, and are accompanied by an Osteoglossoid (_Heterotis_) which has
+hitherto been found in the Nile and on the West Coast only.
+
+Autochthont and limited to this region are the _Mormyridæ_,
+_Pantodontidæ_, and _Kneriidæ_, a singular type, somewhat akin to the
+Loaches. Of Siluroid genera the most characteristic are _Synodontis_,
+_Rhinoglanis_, and the electric _Malapterurus_; of Characinoids,
+_Citharinus_, _Alestes_, _Xenocharax_, _Hydrocyon_, _Distichodon_,
+_Ichthyborus_.
+
+The regions with which Africa (like India) has least similarity
+are, again, the North American and Antarctic. Its affinity with the
+Europe-Asiatic region consists only in having received, like this
+latter, a branch of the Cyprinoids, the African Carps and Barbels
+resembling, on the whole, more Indian than Europo-Asiatic forms. Its
+similarity to Australia is limited to the two regions possessing
+Dipnoous and Osteoglossoid types. But its relations to the two other
+regions of the equatorial zone are near and of great interest.
+
+1. Africa has, in common with India, the Siluroid group of _Clariina_,
+the _Silurina_, and _Bagrina_; and more especially the small but very
+natural family of _Notopteridæ_, represented by three species in
+India, and by two on the _west coast_ of Africa. It would be hazardous
+to state at present in which of the two regions these fishes first
+made their appearance, but the discovery of remains of _Notopteridæ_
+and _Silurina_ in tertiary deposits of Sumatra points to the Indian
+region as their original home. We can have less doubt about the other
+fishes common to both regions; they are clearly immigrants into Africa
+from the East, and it is a remarkable fact that these immigrants
+have penetrated to the most distant limits of Africa in the west as
+well as in the south,--viz. the _Labyrinthici_, represented by two
+genera closely allied to the Indian _Anabas_; the _Ophiocephalidæ_
+and _Mastacembelidæ_, a few species of which have penetrated to the
+west coast, singularly enough being absent from the eastern rivers;
+the _Ariina_, represented by several species, of which one or two
+are identical with Indian, having extended their range along the
+intervening coasts to the east coast of Africa. The Cyprinoids also
+afford an instance of an Indian species ranging into Africa, viz.
+_Discognathus lamta_, which seems to have crossed at the southern
+extremity of the Red Sea, as it is found in the reservoirs at Aden and
+the hill-streams of the opposite coast-region of Abyssinia.
+
+2. No such direct influx of species and genera has occurred from
+South America into Africa. Yet the affinity of their Freshwater
+fishes is striking. Two of the most natural families of fishes, the
+_Chromides_ and _Characinidæ_, are peculiar, and (with the exception of
+_Etroplus_) restricted to them. The African and South American Dipnoi
+are closely allied to each other. The _Pimelodina_, so characteristic
+of Tropical America, have three representatives in Africa, viz.,
+_Pimelodus platychir_, _P. balayi_, and _Auchenoglanis biscutatus_;
+the _Doradina_ are another Siluroid group restricted to these two
+continents.[25] Yet, with all these points of close resemblance, the
+African and South American series are, with the exception of the two
+species of Pimelodus, _generically_ distinct; which shows that the
+separation of the continents must have been of an old date. On the
+other hand, the existence of so many similar forms on both sides of
+the Atlantic affords much support to the supposition that at a former
+period the distance between the present Atlantic continents was much
+less, and that the fishes which have diverged towards the East and
+West are descendants of a common stock which had its home in a region
+now submerged under some intervening part of that ocean. Be this as
+it may, it is evident that the physical conditions of Africa and
+South America have remained unchanged for a considerable period, and
+are still sufficiently alike to preserve the identity of a number of
+peculiar freshwater forms on both sides of the Atlantic. Africa and
+South America are, moreover, the only continents which have produced in
+Freshwater fishes, though in very different families, one of the most
+extraordinary modifications of an organ--the conversion, that is, of
+muscle into an apparatus creating electric force.
+
+C. The boundaries of the TROPICAL AMERICAN (_Neotropical_) REGION
+have been sufficiently indicated in the definition of the Equatorial
+zone. A broad and most irregular band of country, in which the South
+and North American forms are mixed, exists in the north; offering
+some peculiarities which deserve fuller attention in the subsequent
+description of the relations between the South and North American
+faunæ. The following Freshwater fishes inhabit this region:--
+
+    Dipnoi [Australia, Africa]--
+      _Lepidosiren paradoxa_                           1 species.
+
+    _Polycentridæ_                                     3    „
+
+    Chromides [Africa]--
+      _Heros_, _Acara_, _Cichla_, etc.                 80   „
+
+    (_Lucifuga_                                        2    „)
+
+    Siluridæ--
+       _Hypophthalmina_                                5    „
+          Pimelodina [Africa, 2 species]              70    „
+          Ariina [Africa, India, Australia, Fuegian]  35    „
+          Doradina [Africa]                           60    „
+          Hypostomatina [India]                       90    „
+       _Aspredinina_                                   9    „
+          Nematogenyina [Fuegian]--                    2    „
+          Trichomycterina [Fuegian]                    2    „
+       _Stegophilina_                                  3    „
+    Characinidae [Africa]--
+       _Erythrinina_                                  15    „
+       _Curimatina_                                   40    „
+       _Anastomatina_                                 25    „
+          Tetragonopterina                            80    „
+          Hydrocyonina                                30    „
+          Crenuchina                                   1    „
+          Serrasalmonina                              35    „
+
+    Cyprinodontidæ--
+          Carnivoræ [Europe, Asia, N. America,
+              India, Africa]                          30    „
+       _Limnophagæ_                                   31    „
+    Osteoglossidæ [Africa, India, Australia]           2    „
+    _Gymnotidæ_                                       20    „
+    Symbranchidæ [India]                               1    „
+                                                     ------------
+                                                     672 species.
+                                                     ============
+
+Out of the 39 families or groups of Freshwater fishes, 9 only are
+represented in the Tropical American region. This may be accounted for
+by the fact that South America is too much isolated from the other
+regions of the Equatorial zone to have received recent additions to
+its fauna. On the other hand, the number of species exceeds that of
+every other region, even of the Indian, with which, in regard to the
+comparative development of families, the Neotropical region shows great
+analogy, as will be seen from the following Table:--
+
+          INDIAN.               NEOTROPICAL.
+    Siluridæ      200 sp.  Siluridæ       276 sp.
+    Cyprinidæ     330 sp.  Characinidæ    226 sp.
+    Labyrinthici   25 sp.  Chromides       80 sp.
+    Ophiocephalidæ 30 sp.  Cyprinodontidæ  60 sp.
+    Mastacembelidæ 10 sp.  Gymnotidæ       20 sp.
+
+In both regions the great number of species is due to the development
+of numerous local forms of two families, the _Characinidæ_ taking in
+the New World the place of the _Cyprinidæ_ of the Old World. Thereto
+are added a few smaller families with a moderately large number of
+species, which, however, is only a fraction of that of the leading
+families, the remainder of the families being represented by a few
+species only. The number of genera within each of the two regions of
+the two principal families is also singularly alike; the Indian region
+having produced about 45 Siluroid and as many Cyprinoid genera, whilst
+the Neotropical region is tenanted by 54 Siluroid and 40 Characinoid
+genera. These points of similarity between the two regions cannot
+be accidental; they indicate that agreement in their physical and
+hydrographical features which in reality exists.
+
+Of Ganoids, we find in Tropical America one species only, _Lepidosiren
+paradoxa_, accompanied by two Osteoglossoids (_Osteoglossum
+bicirrhosum_ and _Arapaima gigas_).
+
+Autochthont and limited to this region are the _Polycentridæ_, all the
+non-African genera of _Chromides_ and _Characinidæ_; of Siluroids, the
+_Hypophthalmina_, _Aspredinina_, and _Stegophilina_, and the majority
+of _Pimelodina_, _Hypostomatina_, and _Doradina_; the herbivorous
+Cyprinodonts or _Limnophagæ_, and numerous insectivorous Cyprinodonts
+or _Carnivoræ_; and the _Gymnotidæ_ (Electric eel).
+
+The relations to the other regions are as follows:--
+
+1. The resemblances to the Indian and Tropical Pacific regions partly
+date from remote geological epochs, or are partly due to that
+similarity of physical conditions to which we have already referred.
+We have again to draw attention to the unexplained presence in South
+America of a representative of a truly Indian type (not found in
+Africa), viz. _Symbranchus marmoratus_. On the other hand, a
+direct genetic affinity exists between the Neotropical and African
+regions, as has been noticed in the description of the latter, a great
+part of their freshwater fauna consisting of descendants from a common
+stock.
+
+2. A comparison of the specifically Neotropical with the specifically
+North American types shows that no two regions can be more dissimilar.
+It is only in the intervening borderland, and in the large West Indian
+Islands, that the two faunæ mix with each other. We need not enter into
+the details of the physical features of Central America and Mexico--the
+broken ground, the variety of climate (produced by different altitudes)
+within limited districts, the hot and moist alluvial plains surrounding
+the Mexican Gulf, offer a diversity of conditions most favourable to
+the intermixture of the types from the north and the south. But yet
+the exchange of peculiar forms appears to be only beginning; none have
+yet penetrated beyond the debatable ground, and it is evident that the
+land-connection between the two continents is of comparatively recent
+date: a view which is confirmed by the identity of the marine fishes on
+both sides of Central America.
+
+Cuba--and this is the only island in the West Indies which has a
+number of freshwater fishes sufficient for the determination of its
+zoo-geographical relations--is inhabited by several kinds of a perch
+(_Centropomus_), freshwater mullets, Cyprinodonts, one species of
+Chromid (an _Acara_), and _Symbranchus marmoratus_. All these fishes
+are found in Central America, and as they belong to forms known to
+enter brackish water more or less freely, it is evident that they
+have crossed from the mainland of South America or from Central
+America. But with them there came a remarkable North American type,
+_Lepidosteus_. _Lepidosteus viridis_, which is found in the United
+States, has penetrated on the mainland to the Pacific coast of
+Guatemala, where it is common at the mouth of the rivers and in
+brack-water lakes along the coast; it probably crossed into Cuba from
+Florida. A perfectly isolated type of fishes inhabits the subterranean
+waters of the caves of Cuba (two species of _Lucifuga_). The eyes are
+absent or quite rudimentary, as in most other cave animals. Singularly,
+it belongs to a family (_Ophidiidæ_), the members of which are strictly
+marine; and its nearest ally is a genus, _Brotula_, the species of
+which are distributed over the Indo-Pacific Ocean, one only occurring
+in the Caribbean Sea. This type must have witnessed all the geological
+changes which have taken place since Cuba rose above the surface of the
+sea.
+
+A similar mixture of forms of the Tropical and Temperate types of
+Freshwater fishes takes place in the south of South America; its
+details have not yet been so well studied as in the north; but this
+much is evident that, whilst in the East Tropical forms follow the
+Plate river far into the Temperate region, in the West the Temperate
+Fauna finds still a congenial climate in ranges of the Andes, situated
+close to, or even north of, the Tropic.
+
+Like the Indian region, the Tropical American has a peculiar Alpine
+Fauna, the Freshwater fishes of which, however, belong to the
+Siluroids and Cyprinodonts. The former are small, dwarfed forms
+(_Arges_, _Stygogenes_, _Brontes_, _Astroblepus_, _Trichomycterus_,
+_Eremophilus_), and have a perfectly naked body, whilst the
+representatives in the lowlands of, at least, the first four genera are
+mailed. The Alpine Cyprinodonts, on the other hand, (_Orestias_) exceed
+the usual small size of the other members of this family, are covered
+with thick scales, but have lost their ventral fins. Some of these
+Alpine forms, like _Trichomycterus_, follow the range of the Andes far
+into the southern temperate region. The majority reach to a height
+of 15,000 feet above the level of the sea, and a few are found still
+higher.
+
+D. The TROPICAL PACIFIC REGION includes all the islands east of
+Wallace’s Line, New Guinea, Australia--with the exception of its
+south-eastern portion,--and all the islands of the Tropical Pacific to
+the Sandwich group. Comparing the area of this region with that of the
+others, we find it to be not only the poorest in point of the number of
+its species generally, but also in that of the possession of peculiar
+forms, as will appear from the following list:--
+
+    Dipnoi [Neotrop., Africa.]
+      _Ceratodus_                                2 species.
+    Percidæ [Cosmopol.]--
+      Lates (calcarifer) [India]                 1    „
+      _Nannoperca_                               1    „
+      Oligorus [New Zealand]                     1    „
+      Dules [India]                              8    „
+      (_Macquaria_)                              1    „
+    Labyrinthici--
+      Anabas (scandens) [India]                  1    „
+    Ophiocephalidæ--
+      Ophiocephalus (striatus) [India]           1    „
+    Atherinidæ [Brack-water]--
+      Atherinichthys                             2    „
+    Osteoglossidæ [India, Africa, Neotrop.]      1    „
+    Siluridæ--
+      Plotosina [India]                          9    „
+      Ariina [India, Africa, Neotrop.]           7    „
+    Symbranchidæ--
+      Monopterus (javanicus) [India]             1    „
+                                                -----------
+                                        Total   36 species.
+
+The paucity of freshwater fishes is due, in the first place, to the
+arid climate and the deficiency of water in the Australian continent,
+as well as to the insignificant size of the freshwater courses in the
+smaller islands. Still this cannot be the only cause: the large island
+of Celebes, which, by its mountainous portions, as well as by its
+extensive plains and lowlands, would seem to offer a favourable variety
+of conditions for the development of a freshwater Fauna is, as far as
+has been ascertained, tenanted by seven Freshwater fishes only, viz. 2
+_Arius_, 2 _Plotosus_, 1 _Andbas_, 1 _Ophiocephalus_, 1 _Monopterus_,
+all of which are the commonest species of the Indian region. New
+Guinea has not yet been explored, but, from the faunæ nearest to this
+island, we expect its freshwater fishes will prove to be equally few
+in number, and identical with those of Celebes and North Australia; a
+supposition confirmed by the few small collections which have reached
+Europe. Finding, then, that even those parts of this region, which
+are favourable to the development of Freshwater fishes, have not
+produced any distinct forms, and that the few species which inhabit
+them, are unchanged, or but slightly modified Indian species, we must
+conclude that the whole of this area has remained geologically isolated
+from the other regions of this zone since the commencement of the
+existence of Teleostei; and that, with the exception of _Ceratodus_ and
+_Osteoglossum_, the immigration of the other species is of very recent
+date.
+
+Fossil remains of _Ceratodus_ have been found in Liassic and Triassic
+formations of North America, England, Germany, and India; and it is,
+therefore, a type which was widely spread in the Mesozoic epoch.
+Although it would be rash to conclude that its occupation of Australia
+dates equally far back, for it may have reached that continent long
+afterwards; yet it is evident that, as it is one of the most ancient
+of the existing types, so it is certainly the first of the Freshwater
+fishes which appeared in Australia. _Osteoglossum_, of which no fossil
+remains yet have been found, is proved by its distribution to be one
+of the oldest Teleosteous types. There must have been a long gap of
+time before these ancient types were joined by the other Teleostei.
+All of them migrated through the intervening parts of the ocean from
+India. Most of the _Plotosina_, some of the _Arii_, _Dules_, and
+the _Atherinichthys_, also _Nannoperca_ (allied to _Apogon_), were
+among the earliest arrivals, being sufficiently differentiated to
+be specifically or even generically (_Cnidoglanis_, _Nannoperca_)
+distinguished; but some others, like _Anabas scandens_, _Lates
+calcarifer_, _Dules marginatus_, must have reached the Australian
+continent quite recently, for they are indistinguishable from Indian
+specimens.
+
+In South-western Australia a mingling of the scanty fauna with that of
+the southern temperate parts takes place. _Oligorus macquariensis_ (The
+Murray Cod), which has a congener on the coast of New Zealand, ascends
+high up the Murray river, so that we cannot decide whether this Percoid
+should be located in the Tropical or Temperate part of Australia.
+Several _Galaxias_ also extend to the confines of Queensland, and will
+probably some day be found members of this region.
+
+In the smaller Pacific islands the Freshwater fishes exhibit a
+remarkable sameness: two or three species of _Dules_, several Eels, an
+Atherine, or some Gobies, Mullets, and other fishes which with equal
+readiness exchange fresh for salt water, and which would at once reach
+and occupy any streams or freshwater lakes that may be formed on an
+island.
+
+The Sandwich Islands are the only group among the smaller islands which
+are tenanted by a Siluroid, a species of _Arius_, which is closely
+allied to Central American species, and, therefore, probably immigrated
+from Tropical America.
+
+
+                          II. NORTHERN ZONE.
+
+The boundaries of the Northern Zone coincide in the main with the
+northern limit of the Equatorial Zone; but at three different points
+they overlap the latter, as has been already indicated. This happens
+in, and east of, Syria, where the mixed faunæ of the Jordan and the
+rivers of Mesopotamia demand the inclusion of this territory into the
+Northern Zone as well as the Equatorial; in the island of Formosa,
+where a Salmonoid and several Japanese Cyprinoids flourish; and in
+Central America, where a _Lepidosteus_, a Cyprinoid (_Sclerognathus
+meridionalis_), and an Amiurus (_A. meridionalis_) represent the North
+American fauna in the midst of a host of tropical forms.
+
+A separate _Arctic_ Zone does not exist for Freshwater fishes; ichthyic
+life becomes extinct towards the pole as soon as the fresh water
+remains frozen throughout the year, or thaws for a few weeks only; and
+the few fishes which extend into high latitudes, in which lakes are
+open for two or three months in the year, belong to types in no wise
+differing from those of the more temperate south. The highest latitude
+at which fishes have been obtained is 82° lat. N., whence the late
+Arctic Expedition brought back specimens of Charr (_Salmo arcturus_ and
+_Salmo naresii_).
+
+The ichthyological features of this zone are well marked: the
+Chondrosteous Ganoids or Sturgeons, and the families of _Salmonidæ_
+and _Esocidæ_ are limited to, and characteristic of, it; Cyprinoids
+flourish with the Salmonoids, both families preponderating in numbers
+over the others, whilst the Siluroids are few in number and in variety.
+
+The two regions in which this zone is divided are very closely related
+to one another, and their affinity is not unlike that which obtains
+between the sub-regions of the Southern Zone. The subjoined list will
+show their close agreement with regard to families as well as species.
+Several of the latter are common to both, viz.--_Acipenser sturio_,
+_A. maculatu_s, _Perca fluviatilis_, _Gastrosteus pungitius_, _Salmo
+salar_, _Esox lucius_, _Lota vulgaris_, _Petromyzon marinus_, _P.
+fluviatilis_, and _P. branchialis_; and all recent investigations have
+resulted in giving additional evidence of the affinity, and not of the
+diversity of the two regions.
+
+In Europe and temperate Asia, as well as in North America, mountain
+ranges elevated beyond the line of perpetual snow would seem to offer
+physical conditions favourable for the development of a distinct
+alpine fauna. But this is not the case, because the difference of
+climate between the mountain districts and the lowlands is much less in
+this zone than in the Equatorial. Consequently the alpine freshwater
+fishes do not essentially differ from those of the plains; they are
+principally Salmonoids; and in Asia, besides, mountain-barbels and
+Loaches. _Salmo orientalis_ was found by Griffith to abound in the
+tributaries of the Bamean river at an altitude of about 11,000 feet.
+
+
+                                       Europo-Asiatic.   N. American.
+    _Acipenseridæ_--
+      Acipenser                          9 species.      12 species.
+      Scaphirhynchus                     2    „           1    „
+      Polyodon                           1    „           1    „
+    _Lepidosteidæ_                       0    „           3    „
+    _Amiidæ_                             0    „           1    „
+    Percina [Cosmopol.]                 10    „          30    „
+    Grystina [Australia, New Zealand]    0    „           2    „
+    _Centrarchina_                       0    „          26    „
+    _Aphredoderidæ_                      0    „           1    „
+    Cottidæ [partly marine]--
+      _Cottus_                           3    „           8    „
+      _Ptyonotus_                        0    „           1    „
+    _Gastrosteidæ_                       5    „           5    „
+    _Comephoridæ_                        1    „           0    „
+    Gadidæ [marine]--
+      _Lota_                             1    „           1    „
+    Siluridæ--
+      Silurina [India, Africa]           5    „           0    „
+      Bagrina                            2    „           0    „
+      _Amiurina_                         1    „          17    „
+    _Salmonidæ_                         90    „          45    „
+    _Percopsidæ_                         0    „           1    „
+    _Esocidæ_                            1    „           7    „
+    _Umbridæ_                            1    „           1    „
+    Cyprinodontidæ Carnivoræ [India,
+      Africa, Neotrop.]                  9    „          30    „
+    _Heteropygii_                        0    „           2    „
+    Cyprinidæ--
+      _Catostomina_                      1    „          25    „
+      Cyprinina [India, Africa]         80    „          30    ”
+      _Leuciscina_                      60    „          70    „
+      _Rhodeina_                        10    „           0    „
+      Abramidina [India, Africa]        44    „          10    ”
+      Cobitidina [India]                20    „           0    ”
+    _Hyodontidæ_                         0    „           1    „
+    Petromyzontidæ [Southern Zone]       4    „           8    ”
+                                       -----------------------------
+                                       360 species.     339 species.
+                                       =============================
+
+A. THE EUROPO-ASIATIC (PALÆARCTIC) REGION.--Its western and
+southern boundaries coincide with those of the Northern Zone, so that
+only those which divide it from North America have to be indicated.
+Behring’s Strait and the Kamtschatka Sea have been conventionally
+taken as the boundary, but this is shown to be artificial by the fact
+that the animals of both coasts, as far as they are known at present,
+are not sufficiently distinct to be referred to two distinct regions.
+As to the freshwater fishes those of North-western America and of
+Kamtschatka are but imperfectly known, but there can be little doubt
+that the same agreement exists between them as is the case with other
+classes of animals. The Japanese islands exhibit a decided Palæarctic
+fish-fauna, which includes Barbus and Cobitioids, forms strange to the
+North American fauna. A slight influx of tropical forms is perceived in
+the south of Japan, where two Bagrina (_Pseudobagrus aurantiacus_
+and _Liocassis longirostris_) have established themselves for a
+considerable period, for both are peculiar to the island, and have not
+been found elsewhere.
+
+In the east, as well as in the west, the distinction between the
+Europo-Asiatic and North American regions disappears almost entirely
+the farther we advance towards the north. Of four species of the genus
+Salmo known from Iceland, one (_S. salar_) is common to both regions,
+two are European (_S. fario_ and _S. alpinus_), and one is a peculiarly
+Icelandic race (_S. nivalis_). As far as we know the Salmonoids of
+Greenland and Baffin’s Land they are all most closely allied to
+European species, though they may be distinguished as local races.
+
+Finally, as we have seen above, the Europo-Asiatic fauna mingles with
+African and Indian forms in Syria, Persia, and Afghanistan. _Capoëta_,
+a Cyprinoid genus, is characteristic of this district, and well
+represented in the Jordan and rivers of Mesopotamia.
+
+Assuming that the distribution of Cyprinoids has taken its origin from
+the alpine tract of country dividing the Indian and Palæarctic regions,
+we find that this type has found in the temperate region as equally
+favourable conditions for its development as in the tropical. Out of
+the 360 species known to exist in the Palæarctic regions, no less than
+215 are Cyprinoids. In the countries and on the plateaus immediately
+joining the Himalayan ranges those mountain forms which we mentioned
+as peculiar to the Indian Alps abound and extend for a considerable
+distance towards the west and east, mixed with other _Cyprinina_
+and _Cobitidina_. The representatives of these two groups are more
+numerous in Central and Eastern Asia than in Europe and the northern
+parts of Asia, where the _Leuciscina_ predominate. _Abramidina_ or
+Breams are more numerous in the south and east of Asia, but they
+spread to the extreme north-western and northern limits, to which the
+Cyprinoid type reaches. The _Rhodeina_ are a small family especially
+characteristic of the East, but with one or two off-shoots in Central
+Europe. Very significant is the appearance in China of a species of the
+_Catostomina_, a group otherwise limited to North America.
+
+The Cyprinoids, in their dispersal from the south northwards, are
+met from the opposite direction by the Salmonoids. These fishes are,
+without doubt, one of the youngest families of _Teleostei_, for they
+did not appear before the Pliocene era; they flourished at any rate
+during the glacial period, and, as is testified by the remnants which
+we find in isolated elevated positions, like the Trout of the Atlas,
+of the mountains of Asia-Minor, and of the Hindu Kush, they spread to
+the extreme south of this region. At the present day they are most
+numerously represented in its northern temperate parts; towards the
+south they become scarcer, but increase again in numbers and species,
+wherever a great elevation offers them the snow-fed waters which they
+affect. In the rivers of the Mediterranean Salmonoids are by no means
+scarce, but they prefer the upper courses of those rivers, and do not
+migrate to the sea.
+
+The Pike, Umbra, several species of Perch and Stickleback, are also
+clearly autochthont species of this region. Others belong to marine
+types, and seem to have been retained in fresh water at various epochs:
+thus the freshwater Cottus (Miller’s Thumb); _Cottus quadricornis_,
+which inhabits lakes of Scandinavia, whilst other individuals of the
+same species are strictly marine; the Burbot (_Lota vulgaris_); and the
+singular _Comephorus_, a dwarfed and much-changed Gadoid which inhabits
+the greatest depths of Lake Baikal.
+
+Remnants of the Palæichthyic fauna are the _Sturgeons_ and _Lampreys_.
+The former inhabit in abundance the great rivers of Eastern Europe and
+Asia, periodically ascending them from the sea; their southernmost
+limits are the Yangtse-kiang in the east, and rivers flowing into the
+Adriatic, Black and Caspian Seas, and Lake Aral, towards the centre of
+this region. None are known to have gone beyond the boundaries of the
+Northern Zone. If the Lampreys are justly reckoned among Freshwater
+fishes, their distribution is unique and exceptional. In the Palæarctic
+region some of the species descend periodically to the sea, whilst
+others remain stationary in the rivers; the same has been observed
+in the Lampreys of North America. They are entirely absent in the
+Equatorial Zone, but reappear in the Temperate Zone of the Southern
+Hemisphere. Many points of the organisation of the Cyclostomes indicate
+that they are a type of great antiquity.
+
+The remaining Palæarctic fishes are clearly immigrants from
+neighbouring regions: thus _Silurus_, _Macrones_, and _Pseudobagrus_
+from the Indian region; _Amiurus_ (and, as mentioned above,
+_Catostomus_) from North America. The Cyprinodonts are restricted to
+the southern and warmer parts; all belong to the carnivorous division.
+The facility with which these fishes accommodate themselves to a
+sojourn in fresh, brackish, or salt water, and even in thermal springs,
+renders their general distribution easily comprehensible, but it is
+impossible to decide to which region they originally belonged; their
+remains in tertiary deposits round the Mediterranean are not rare.
+
+       *       *       *       *       *
+
+_B_. The boundaries of the NORTH AMERICAN or NEARCTIC REGION have
+been sufficiently indicated. The main features and the distribution
+of this fauna are identical with those of the preceding region. The
+proportion of Cyprinoid species to the total number of North-American
+fishes (135:339) appears to be considerably less than in the Palæarctic
+region, but we cannot admit that these figures approach the truth,
+as the Cyprinoids of North America have been much less studied than
+those of Europe; of many scarcely more than the name is known. This
+also applies in a great measure to the Salmonoids, of which only half
+as many as are found in the Palæarctic region have been sufficiently
+described to be worthy of consideration. North America will, without
+doubt, in the end show as many distinct races as Europe and Asia.
+
+Cyprinoids, belonging to genera living as well as extinct, existed
+in North America in the tertiary period. At present, _Cyprinina_,
+_Leuciscina_, and _Abramidina_ are well represented, but there
+is no representative of the Old World genus _Barbus_, or of the
+_Cobitidina_[26]; _Rhodeina_ are also absent. On the other hand, a
+well-marked Cyprinoid type is developed--the _Catostomina_, of which
+one species has, as it were, returned into Asia. Very characteristic is
+the group of _Centrarchina_, allied to the Perch, of which there are
+some thirty species; two _Grystina_. Of the Sticklebacks there are as
+many species as in Europe, and of Pike not less than seven species have
+been distinguished. _Umbra_ appears to be as local as in Europe. Some
+very remarkable forms, types of distinct families, though represented
+by one or two species only, complete the number of North American
+autochthont fishes--viz., _Aphredoderus_, _Percopsis_, _Hyodon_, and
+the _Heteropygii_ (_Amblyopsis_ and _Chologaster_). The last are
+allied to the Cyprinodonts, differing from them in some points of the
+structure of their intestines. The two genera are extremely similar,
+but _Chologaster_, which is found in ditches of the rice-fields of
+South Carolina, is provided with eyes, and lacks the ventral fins.
+_Amblyopsis_ is the celebrated Blind Fish of the Mammoth Cave of
+Kentucky: colourless, eyeless, with rudimentary ventral fins, which may
+be occasionally entirely absent.
+
+A peculiar feature of the North American Fish Fauna is that it has
+retained, besides the Sturgeons and Lampreys, representatives of two
+Ganoid families, _Lepidosteus_ and _Amia_. Both these genera existed
+in tertiary times: the former occurs in tertiary deposits of Europe as
+well as North America, whilst fossil remains of _Amia_ have been found
+in the Western Hemisphere only.
+
+It is difficult to account for the presence of the _Amiurina_ in North
+America. They form a well-marked division of the _Bagrina_, which
+are well represented in Africa and the East Indies, but absent in
+South America; it is evident, therefore, they should not be regarded
+as immigrants from the south, as is the case with the Palæarctic
+Siluroids. Nor, again, has the connection between South and North
+America been established sufficiently long to admit of the supposition
+that these Siluroids could have spread in the interval from the south
+to the northern parts of the continent, for some of the species are
+found as far north as Pine Islands Lake (54° lat. N.)[27]
+
+
+                          III. SOUTHERN ZONE.
+
+The boundaries of this zone have been indicated in the description of
+the Equatorial Zone; they overlap the southern boundaries of the latter
+in South Australia and South America, but we have not at present the
+means of exactly defining the limits to which southern types extend
+northwards. This zone includes Tasmania with at least a portion of
+South-eastern Australia (_Tasmanian sub-region_), New Zealand and the
+Auckland Islands (_New Zealand sub-region_), and Chili, Patagonia,
+Terra del Fuego, and the Falkland Islands (_Fuegian sub-region_). No
+freshwater fishes are known from Kerguelen’s Land, or from islands
+beyond 55° lat. S. The southern extremity of Africa has to be excluded
+from this zone so far as Freshwater fishes are concerned.
+
+This zone is, with regard to its extent as well as to the number of
+species, the smallest of the three; yet its ichthyological features
+are well marked; they consist in the presence of two peculiar
+families, each of which is analogous to a northern type, viz. the
+_Haplochitonidæ_, which represent the _Salmonidæ_, _Haplochiton_ being
+the analogue of _Salmo_, and _Prototroctes_ that of _Coregonus_; and
+the _Galaxiidæ_, which are the Pikes of the Southern Hemisphere.
+
+Although geographically widely separate from each other, the Freshwater
+fishes of the three divisions are nevertheless so closely allied
+that conclusions drawn from this group of animals alone would hardly
+justify us in regarding these divisions as sub-regions. One species of
+_Galaxias_ (_G. attenuatus_) and the three Lampreys are found in all
+three, or at least two, sub-regions.
+
+            _Freshwater Fishes of the Southern Zone._
+
+                                  Tasmanian. N. Zealand. Fuegian.
+
+    _Percichthys_                    ...          ...         3
+
+    Siluridæ--
+      _Diplomystax_                  ...          ...         1
+      _Nematogenys_                  ...          ...         1
+      Trichomycterina [Neotrop.]     ...          ...         5
+
+    _Gadopsidæ_                        1          ...       ...
+
+    (_Retropinna_                    ...            1       ...)
+
+    _Haplochitonidæ_                   1            1          1
+
+    _Galaxiidæ_                        6            5          4
+
+    Petromyzontidæ                     3            1          3
+                                      --           --         --
+                                      11            8         18
+
+But little remains to be added in explanation of this list;
+_Percichthys_ is in Chili the autochthont form of the cosmopolitan
+group of _Percina_. _Diplomystax_, an Arioid fish of Chili, and
+_Nematogenys_ seem to have crossed the Andes from Tropical America
+at a comparatively early period, as these genera are not represented
+on the eastern side of South America; the _Trichomycterina_ occur on
+both sides of the Andes, which they ascend to a considerable height.
+_Retropinna_ is a true Salmonoid, allied to, and representing in the
+Southern Hemisphere the Northern Smelt, _Osmerus_. In both these
+genera a part of the specimens live in the sea, and ascend rivers
+periodically to spawn; another part remain in rivers and lakes, where
+they propagate, never descending to the sea, this freshwater race
+being constantly smaller than their marine brethren. That this small
+Teleostean of the Northern Hemisphere should reappear, though in a
+generically modified form, in New Zealand, without having spread over
+other parts of the Southern Zone, is one of the most remarkable, and
+at present inexplicable facts of the geographical distribution of
+freshwater fishes.
+
+  [Illustration: Fig. 104.--_Haplochiton zebra_, Straits of
+  Magelhæn.]
+
+
+
+
+                            CHAPTER XVIII.
+
+                   THE FISHES OF THE BRACKISH WATER.
+
+
+On such parts of a coast at which there is a mixture of fresh and salt
+water, either in consequence of some river emptying its water into the
+sea or from an accumulation of land surface water forming lagunes,
+which are in uninterrupted or temporary communication with the sea,
+there flourishes a peculiar brackish water fauna which is characterised
+by the presence of fishes found sometimes in sea-, sometimes in pure
+freshwater.
+
+This fauna can be rather sharply defined if a limited district only
+is taken into consideration; thus, the species of the brackish water
+fauna of Great Britain, the Pacific coast of Central America, of
+the larger East India Islands, etc., can be enumerated without much
+hesitation. But difficulties arise when we attempt to generalise in the
+enumeration of the forms referable to the brackish water fauna; because
+the genera and families enumerated include certain species and genera
+which have habituated themselves exclusively either to a freshwater or
+marine existence; and, besides, because a species of fish may be at
+one locality an inhabitant of brackish water, at another of the sea,
+and at a third of fresh water. The circumstance that these fishes can
+live in sea and fresh water has enabled them to spread readily over the
+globe, a few only being limited to particular regions; therefore, for
+the purposes of dividing the earth’s surface into natural zoological
+regions the brackish water forms are useless. The following fishes may
+be referred to this Fauna:--
+
+1. Species of _Rajidæ_ (_Raja_, _Trygon_) prefer the mouths of rivers,
+probably because the muddy or sandy bottom offers the most suitable
+conditions for fishes which can feed on the bottom only; such brackish
+water species belong chiefly to the Equatorial Zone, some having taken
+up their abode entirely in fresh water (South American Trygons).
+
+2. _Ambassis_, a Percoid genus, consisting of numerous small species,
+inhabiting the shores of the tropical parts of the Indian Ocean and
+the coasts of Tropical Australia. Many species enter, and all seek the
+neighbourhood of, fresh water; hence they disappear in the islands of
+the Pacific, and are scarce in the Red Sea.
+
+3. _Therapon_, with the same distribution as the former.
+
+4. Numerous _Sciænidæ_ of the Equatorial Zone.
+
+5. The _Polynemidæ_, chiefly inhabitants of brackish water of the
+Equatorial Zone, most developed in the Indian region, and scarce in the
+Tropical Pacific.
+
+6. Numerous species of _Caranx_ (or Horse Mackerels) of the Equatorial
+Zone.
+
+7. Nearly all species of _Gastrosteus_ enter brackish water, _G.
+spinachia_ being almost exclusively confined to it: Northern Zone.
+
+8. The most important genera of the Gobies (_Gobiina_): _Gobius_
+(nearly cosmopolitan), _Sicydium_, _Boleophthalmus_, _Periophthalmus_,
+_Eleotris_ (equatorial). Many of the species are entirely confined to
+fresh water.
+
+9. The _Amblyopina_, similar to the Gobies, but with more elongated
+body: Tropical Indo-Pacific.
+
+10. The _Trypauchenina_: Coasts of the Indian region.
+
+11. Many species of _Blennius_, of which several are found far inland
+in fresh waters--for instance in North Italy, in the Lake of Galilee,
+in the eastern parts of Asia Minor.
+
+12. The majority of _Atherinidæ_, and
+
+13. The _Mugilidæ_: both families being most numerous and abundant in
+brackish water, and almost cosmopolitan.
+
+14. Many _Pleuronectidæ_ prefer the mouths of rivers for the same
+reason as the Rays; some ascend rivers, as the Flounder, _Cynoglossus_,
+etc.
+
+15. Several _Siluridæ_, as especially the genera _Plotosus_,
+_Cnidoglanis_, _Arius_, which attain their greatest development in
+brackish water.
+
+16. The _Cyprinodontidæ_ are frequently found in brackish water.
+
+17. Species of _Clupea_, some of which ascend rivers, and become
+acclimatized in fresh water, as _Clupea finta_, which has established
+itself in the lakes of northern Italy.
+
+18. _Chatoessus_, a genus of Clupeoid fishes of the Equatorial Zone, of
+which some species have spread into the Northern Zone.
+
+19. _Megalops_: Equatorial Zone.
+
+20. _Anguilla._ The distribution, no less than the mode of propagation,
+and the habits generally, of the so-called Freshwater-eels still
+present us with many difficult problems. As far as we know at present
+their birthplace seems to be the coast in the immediate neighbourhood
+of the mouths of rivers. They are much more frequently found in fresh
+water than in brackish water, but the distribution of some species
+proves that they at times migrate by sea as well as by land and river.
+Thus _Anguilla mauritiana_ is found in almost all the fresh and
+brackish waters of the islands of the Tropical Indian Ocean and Western
+Pacific, from the Comoros to the South Sea; _Anguilla vulgaris_ is
+spread over temperate Europe (exclusive of the system of the Danube,
+the Black and Caspian Seas), in the Mediterranean district (including
+the Nile and rivers of Syria), and on the Atlantic coast of North
+America; _Anguilla bostoniensis_, in Eastern North America, China,
+and Japan; _Anguilla lati__rostris_, in Temperate Europe, the whole
+Mediterranean district, the West Indies, China, and New Zealand. The
+other more local species are found, in addition to localities already
+mentioned, on the East Coast of Africa, South Africa, on the continent
+of India, various East Indian Islands, Australia, Tasmania, Auckland
+Islands; but none have ever been found in South America, the West Coast
+of North America, and the West Coast of Africa: surely one of the most
+striking instances of irregular geographical distribution.
+
+21. Numerous _Syngnathidæ_ have established themselves in the Northern
+Zone as well as in the Equatorial, in the vegetation which flourishes
+in brackish water.
+
+This list could be considerably increased if an enumeration of species,
+especially of certain localities, were attempted; but this is more a
+subject of local interest, and would carry us beyond the scope of a
+general account of the distribution of Fishes.
+
+  [Illustration: Fig. 105.--_Mugil octo-radiatus._]
+
+  [Illustration: Fig. 106.--_Mugil auratus._]
+
+  [Illustration: Fig. 107.--_Mugil septentrionalis._
+
+   Heads of Grey Mullets, fishes of Brackish water.]
+
+
+
+
+                             CHAPTER XIX.
+
+                  THE DISTRIBUTION OF MARINE FISHES.
+
+
+Marine fishes fall, with regard to their mode of life and distribution,
+into three distinct categories:--
+
+1. _Shore Fishes_--That is, fishes which inhabit chiefly parts of the
+sea in the immediate neighbourhood of land either actually raised
+above, or at least but little submerged below, the surface of the
+water. They do not descend to any great depth,--very few to 300
+fathoms, and the majority live close to the surface. The distribution
+of these fishes is determined not only by the temperature of the
+surface water but also by the nature of the adjacent land, and its
+animal and vegetable products; some of these fishes being confined to
+flat coasts with soft or sandy bottoms, others to rocky and fissured
+coasts, others to living coral formations. If it were not for the
+frequent mechanical and involuntary removals to which these fishes
+are exposed, their distribution within certain limits, as it no doubt
+originally existed, would resemble still more that of freshwater fishes
+than we find it actually does at the present period.
+
+2. _Pelagic Fishes_--that is, fishes which inhabit the surface and
+uppermost strata of the open ocean, which approach the shores only
+accidentally, or occasionally (in search of prey), or periodically
+(for the purpose of spawning). The majority spawn in the open sea,
+their ova and young being always found at great distance from the
+shore. With regard to their distribution, they are still subject to
+the influences of light and the temperature of the surface water; but
+they are independent of the variable local conditions which tie the
+shore fish to its original home, and therefore roam freely over a space
+which would take a freshwater or shore fish thousands of years to cover
+in its gradual dispersal. Such as are devoid of rapidity of motion
+are dispersed over similarly large areas by the oceanic currents,
+more slowly than, but as surely as, the strong swimmers. Therefore,
+an accurate definition of their distribution within certain areas
+equivalent to the terrestrial regions is much less feasible than in the
+case of shore fishes.
+
+3. _Deep-sea Fishes_--that is, fishes which inhabit such depths of the
+ocean as to be but little or not influenced by light or the surface
+temperature; and which, by their organisation are prevented from
+reaching the surface stratum in a healthy condition. Living almost
+under identical tellurian conditions, the same type, the same species,
+may inhabit an abyssal depth under the equator as well as one near the
+arctic or antarctic circle; and all we know of these fishes points to
+the conclusion that no separate horizontal regions can be distinguished
+in the abyssal fauna, and that no division into bathymetrical strata
+can be attempted on the base of generic much less of family characters.
+
+It must not be imagined that these three categories are more sharply
+defined than Freshwater and Marine Fishes. They gradually pass into
+each other, and there are numerous fishes about which uncertainty
+exists whether they should be placed in the Shore or Pelagic series, or
+in the Pelagic or Deep-sea series; nay, many facts favour the view that
+changes in the mode of life and distribution of fishes are still in
+progress.
+
+The change in habitat of numerous fishes is regulated by the
+distribution of their favourite food. At certain seasons the surface
+of the sea in the vicinity of land swarms with mollusks, larval
+Crustaceans, Medusæ, attracting shoals of fishes from the open ocean
+to the shores; and these are again pursued by fishes of larger size and
+predacious habits, so that all these fishes might be included, with
+equal propriety, in the littoral or pelagic series. However, species
+which are known to normally spawn in the open ocean must be always
+referred to the latter division.
+
+Chondropterygii, Acanthopterygii, Anacanths, Myxinoids, and
+Pharyngobranchii furnish the principal contingents to the Marine Fauna;
+whilst the majority of Malacopterygians, the Ganoids, and Cyclostomes
+are Freshwater Fishes.
+
+
+                   I.--DISTRIBUTION OF SHORE FISHES.
+
+       The principal types of Shore-fishes are the following:--
+
+    CHONDROPTERYGII--
+      HOLOCEPHALA                                  4 species
+      PLAGIOSTOMATA--
+        _Carchariidæ_ (part.)                     12    „
+        _Scylliidæ_                               30    „
+        _Cestraciontidæ_                           4    „
+        _Spinacidæ_ (part.)                        8    „
+        _Rhinidæ_                                  1    „
+        _Pristiophoridæ_                           4    „
+        _Pristidæ_                                 5    „
+        _Rhinobatidæ_                             14    „
+        _Torpedinidæ_                             15    „
+        _Rajidæ_                                  34    „
+        _Trygonidæ_                               47    „
+
+    ACANTHOPTERYGII--
+      _Percidæ_ (part. incl. Pristipomatidæ)     625    „
+      _Mullidæ_                                   35    „
+      _Sparidæ_                                  130    „
+      _Squamipinnes_                             130    „
+      _Cirrhitidæ_                                40    „
+      _Heterolepidina_                            12    „
+      _Scorpænidæ_                               120    „
+      _Cottiæ_ (part.)                           100    „
+      _Cataphracti_ (part.)                       20    „
+      _Trachinidæ_                               100    „
+      _Sciænidæ_                                 100    „
+      _Sphyrænidæ_                                15    „
+      _Trichiuridæ_                               17    „
+      _Elacate_                                    1    „
+      _Nomeidæ_ (part.)                            5    „
+      _Cyttidæ_                                    8    „
+      _Stromateus_                                 9    „
+      _Mene_                                       1    „
+      _Carangidæ_ (part.)                        130    „
+      _Kurtidæ_                                    7    „
+      _Gobiodon_                                   7    „
+      _Callionymina_                              30    „
+      _Discoboli_                                 11    „
+      _Batrachidæ_                                14    „
+      _Pediculati_ (part.)                        11    „
+      _Blenniidæ_                                 90    „
+      _Acanthoclinidæ_                             1    „
+      _Teuthididæ_                                30    „
+      _Acronuridæ_                                60    „
+      _Hoplognathidæ_                              3    „
+      _Malacanthidæ_                               3    „
+      _Plesiopina_                                 4    „
+      _Trichonotidæ_                               2    „
+      _Cepolidæ_                                   7    „
+      _Gobiesocidæ_                               21    „
+      _Psychrolutidæ_                              2    „
+      _Centriscidæ_                                7    „
+      _Fistulariidæ_                               4    „
+
+    ACANTHOPTERYGII PHARYNGOGNATHI--
+
+        _Pomacentridæ_                           150    „
+        _Labridæ_                                400    „
+        _Embiotocidæ_                             17    „
+
+    ANACANTHINI--
+
+        _Gadopsidæ_                                1    „
+        _Lycodidæ_                                15    „
+        _Gadidæ_ (part.)                          50    „
+        _Ophidiidæ_ (part.)                       40    „
+        _Pleuronectidæ_                          160    „
+
+    PHYSOSTOMI--
+
+        _Saurina_ (part.)                         16    „
+        _Salmonidæ_ (part.)                        7    „
+        _Clupeidæ_ (part.)                       130    „
+        _Chirocentridæ_                            1    „
+        _Chilobranchus_                            1    „
+        _Murænidæ_ (part.)                       200    „
+        _Pegasidæ_                                 4    „
+
+    LOPHOBRANCHII                                120    „
+
+    PLECTOGNATHI--
+
+        _Sclerodermi_                             95    „
+        _Gymnodontes_                             83    „
+
+    CYCLOSTOMATA--
+
+        MYXINIDÆ                                   5    „
+
+    LEPTOCARDII                                    2    „
+                                                -------------
+                                                3587 species.
+                                                =============
+
+These types of Shore fishes are divided among the following oceanic
+areæ:--
+
+       I. The Arctic Ocean.
+
+      II. The Northern Temperate Zone.
+
+            A. The Temperate North Atlantic.
+                 1. The British district.
+                 2. The Mediterranean district.
+                 3. The North American district.
+
+            B. The Temperate North Pacific.
+                 1. The Kamtschatkan district.
+                 2. The Japanese district.
+                 3. The Californian district.
+
+    III. The Equatorial Zone.
+         A. The Tropical Atlantic.
+         B. The Tropical Indo-Pacific.
+         C. The Pacific Coast of Tropical America.
+             1. The Central American district.
+             2. The Galapagoes district.
+             3. The Peruvian district.
+
+    IV. The Southern Temperate Zone.
+             1. The Cape of Good Hope district.
+             2. The South Australian district.
+             3. The Chilian district.
+             4. The Patagonian district.
+
+    V. The Antarctic Ocean.
+
+As with freshwater fishes, the main divisions of the Shore-fish faunæ
+are determined by their distance from the equator, the equatorial
+zone of the Freshwater series corresponding entirely to that of
+the Shore-fish series. But as Marine fishes extend farther towards
+the Poles than Freshwater fishes, and as the polar types are more
+specialised, a distinct Arctic and Antarctic fauna may be separated
+from the faunæ of the temperate zones. The two subdivisions of the
+Northern temperate zone in the Freshwater series are quite analogous
+to the corresponding divisions in the Coast series. In the Southern
+Hemisphere the Shore-fishes of the extremity of Africa form a separate
+district of the temperate zone, whilst the Freshwater fishes of
+South Africa were found to be tropical types. The Marine series of
+the Southern temperate zone is also much more diversified than the
+Freshwater series, and admits of further subdivision, which, although
+in some degree indicated in the Freshwater series, does not entirely
+correspond to that proposed for the latter.
+
+
+                 I. SHORE FISHES OF THE ARCTIC OCEAN.
+
+The Shore fishes clearly prove a continuity of the Arctic circumpolar
+fauna, as the southern limit of which we may indicate the southern
+extremity of Greenland and the Aleutian Archipelago, or 60° of lat. N.
+
+Towards the North, fishes become less in variety of species and fewer
+in number of individuals, and only very few genera are restricted to
+this fauna.
+
+The highest latitude at which Shore fishes have been observed is
+83° N. lat. The late Arctic Expedition collected at and near that
+latitude specimens of _Cottus quadricornis_, _Icelus hamatus_,
+_Cyclopterus spinosus_, _Liparis fabricii_, _Gymnelis viridis_, and
+_Gadus fabricii_. This number probably would have been larger if the
+difficulties of collecting fishes in those high latitudes were not
+almost insuperable for the greater part of the year.
+
+As far as we know, the fishes north and south of Behring’s Straits
+belong to the same generic or family types as those of the
+corresponding latitudes of the Eastern Hemisphere, though the majority
+are specifically distinct. But the information we possess of the fishes
+of the northernmost extremity of the Pacific is extremely scanty and
+vague. Farther south, whence now and then a collection reaches Europe,
+we meet with some European species, as the Herring, Halibut, Hake.
+
+The Chondropterygians are very scarce, and it is doubtful whether
+another Chondropterygian, beside the pelagic _Læmargus_ or Greenland
+Shark, crosses the Arctic circle. In the more temperate latitudes
+of South Greenland, Iceland, and Northern Scandinavia, _Acanthias_,
+_Centroscyllium_, and a species of _Raja_, also _Chimæra_, are met with.
+
+Of Acanthopterygians the families of _Cottidæ_, _Cataphracti_,
+_Discoboli_, and _Blenniidæ_ are well represented, and several of
+the genera are characteristic of the Arctic fauna: marine species
+of _Cottus_; _Centridermichthys_, _Icelus_, _Triglops_; _Agonus_,
+_Aspidophoroides_; _Anarrhichas_, _Centronotus_, _Stichæus_;
+_Cyclopterus_ and _Liparis_. Two species of _Sebastes_ are rather
+common.
+
+Characteristic is also the development of Gadoid fishes, of which some
+thirteen species, belonging to _Gadus_, _Merluccius_, and _Molva_,
+form one of the principal articles of food to the inhabitants of the
+coasts of the Arctic Ocean. The Blennioid Anacanthini or _Lycodidæ_,
+are limited to the Arctic and Antarctic coasts. _Ammodytes_ and a few
+Flat-fishes (_Hippoglossoides_ and _Pleuronectes_) are common in the
+more temperate parts.
+
+Labroids only exceptionally penetrate so far towards the north.
+
+Physostomes are very scarce, and represented only by a few species of
+_Clupea_ and by _Mallotus_; the latter is an ancient inhabitant of the
+Greenland coasts, fossil remains, indistinguishable from the species
+of the present day, being frequently found in nodules of clay of
+comparatively recent formation.
+
+The Arctic climate is still less favourable to the existence of
+Lophobranchs, only a few _Syngnathus_ and _Nerophis_ being present in
+the more southern latitudes, to which they have been carried by oceanic
+currents from their more congenial home in the south. Scleroderms and
+Plectognaths are entirely absent.
+
+The Gadoids are accompanied by _Myxine_, which parasitically thrives in
+them.
+
+
+                   II. THE NORTHERN TEMPERATE ZONE.
+
+
+          A. _Shore Fishes of the Temperate North Atlantic_.
+
+This part of the fauna may be subdivided into three districts:--
+
+1. The fishes of the north-eastern shores, viz. of the British
+islands, of Scandinavia so far as it is not included in the Arctic
+fauna, and of the continent of Europe southwards to about 40° of lat.
+N.--_British_ district.
+
+2. The fishes of the Mediterranean shores and of the adjoining shores
+of the Atlantic, including the Azores, Madeira, and the Canary
+Islands--_Mediterranean_ district.
+
+3. The fishes of the western shores, from 60° lat. N. to about 30° lat.
+N.--the _North American_ district.
+
+1. The _British_ district shows scarcely any marked distinctive
+features; the character of its fauna is simply intermediate between
+that of the Arctic Ocean and the Mediterranean district; truly Arctic
+forms disappear, while such as are also found in the Mediterranean make
+their appearance. Also with regard to the abundance of individuals
+and variety of fishes this district forms a transition from the north
+towards the south.
+
+Besides the few Arctic Chondropterygians, all of which extend into this
+district, the small shore Dog-fishes are well represented (_Mustelus_,
+_Galeus_, _Scyllium_, _Pristiurus_); the ubiquitous Rhina or Monk-fish
+is common; of Rays, _Raja_ predominates in a variety of species over
+_Torpedo_ and _Trygon_, which are still scarce.
+
+Of Acanthopterygians, _Centridermichthys_, _Icelus_, _Triglops_, and
+_Aspidophoroides_, do not extend from the north into this district; and
+_Cottus_, _Anarrhichas_, _Centronotus_, _Stichæus_, the _Discoboli_
+disappear within its limits. Nearly all the remainder are genera which
+are also found in the Mediterranean districts. The following are the
+principal forms, and known to propagate on these shores: _Labrax_;
+_Serranus_, _Polyprion_, _Dentex_; _Mullus_; _Cantharus_, _Pagrus_,
+_Pagellus_; _Sebastes_; _Cottus_, _Trigla_, _Agonus_; _Trachinus_;
+_Sciæna_ (?); _Zeus_; _Trachurus_, _Capros_; _Callionymus_;
+_Discoboli_; _Lophius_; _Anarrhichas_, _Centronotus_, _Stich__æus_;
+_Blenniops_, _Zoarces_ (not in Mediterranean); _Cepola_; _Lepadogaster_.
+
+Of the Anacanthini the Gadoids are as numerous as in the Arctic
+Ocean, most being common to both districts; they are represented by
+_Gadus_, _Gadiculus_, _Merluccius_, _Phycis_, _Molva_, _Motella_,
+_Raniceps_, and _Brosmius_; but, whilst the majority show their
+northern origin by not extending into the Mediterranean, _Ammodytes_
+and most _Pleuronectidæ_ prove themselves to be the more southern
+representatives of this order. In the British district we find
+_Hippoglossus_, _Hippoglossoides_, _Rhombus_, _Phrynorhombus_,
+_Pleuronectes_, _Solea_, and only the two first are not met with in the
+Mediterranean.
+
+Labroids are common; with the exception of the North American
+_Tautoga_, all the other genera are met with.
+
+Physostomes are not well represented, viz. by one species of _Osmerus_,
+one of _Engraulis_, one of _Conger_, and about five of _Clupea_.
+
+_Syngnathus_ and _Nerophis_ become more common as we proceed
+southwards; but the existence of Scleroderms and Plectognaths is
+indicated by single individuals only, stragglers from their southern
+home, and unable to establish themselves in a climate ungenial to them.
+
+The Gadoids are accompanied by _Myxine_; and _Branchiostoma_ may be
+found in all suitable localities.
+
+2. The _Mediterranean_ district is distinguished by a great variety of
+forms; yet, with the exception of a few genera established for single
+species, none of the forms can be considered peculiar to it; and even
+that small number of peculiar genera is more and more diminished as
+our knowledge of the distribution of fishes advances. Some genera are
+identical with those found on the western coasts of the Atlantic and in
+the West Indies; but a most remarkable and unexpected affinity obtains
+with another very distant fauna, viz. that of Japan. The number of
+genera common to the Mediterranean district and the Japanese coasts
+is larger than that of the genera common to the Mediterranean and the
+opposite American coasts.
+
+The Chondropterygians found in the British district continue in the
+Mediterranean, their number being increased by _Centrina_, _Spinax_,
+_Pteroplatea_, and some species of _Rhinobatus_, a genus more
+numerously represented in the Tropics. _Torpedo_ and _Trygon_ are
+common.
+
+The greatest variety belong to the Acanthopterygians, as will be seen
+from the following list:--_Labrax_; _Anthias_, _Serranus_, _Polyprion_,
+_Apogon_, _Pomatomus_, _Pristipoma_, _Diagramma_ (an Indian genus
+with two Mediterranean species, and otherwise not represented in the
+Atlantic), _Dentex_, _Mæna_, _Smaris_; _Mullus_; _Cantharus_, _Box_,
+_Scatharxs_, _Oblata_, _Sargus_, _Pagrus_, _Pagellus_, _Chrysophrys_;
+_Sebastes_, _Scorpæna_; _Hoplostethus_, _Beryx_, _Polymixia_; _Trigla_,
+_Lepidotrigla_, _Agonus_, _Peristethus_; _Trachinus_, _Uranoscopus_;
+_Umbrina_, _Sciæna_; _Sphyræna_; _Aphanopus_, _Lepidopus_,
+_Nesiarchus_, _Trichiurus_, _Thyrsites_; _Cubiceps_; _Zeus_, _Cyttus_;
+_Stromateus_; _Trachurus_, _Caranx_, _Capros_, _Diretmus_, _Antigonia_;
+_Callionymus_; _Batrachus_; _Lophius_; _Cristiceps_, _Tripterygium_;
+_Cepola_; _Lepadogaster_; _Centriscus_; _Notacanthus_.
+
+The _Labridæ_ are as common as, or even more so than, in the British
+district, and represented by the same genera. But, besides, some
+other Pharyngognaths, properly belonging to the Tropical Atlantic,
+have fully established themselves, though only by a few species, viz.
+_Glyphidodon_ and _Heliastes_; _Cossyphus_, _Novacula_, _Julis_,
+_Coris_, and _Scarus_.
+
+The Gadoids show a marked decrease of development; and the species of
+_Gadus_, _Gadiculus_, _Mora_, _Strinsia_, _Phycis_, and _Molva_, which
+are peculiar to the Mediterranean, seem to inhabit rather the colder
+water of moderate depths, than the surface near the shore. _Motella_,
+however, proves to be a true Shore fish also in the Mediterranean,
+at least in its adult state. _Ophidium_ and _Fierasfer_ appear now
+besides _Ammodytes_. As the Gadoids decrease, so the _Pleuronectidæ_
+increase, the genera of the Mediterranean district being _Rhombus_,
+_Phrynorhombus_, _Arnoglossus_, _Citharus_, _Rhomboidichthys_,
+_Pleuronectes_ (a northern genus not extending farther southwards),
+_Solea_, _Synaptura_, and _Ammopleurops_.
+
+The variety of Physostomes is small; the following only being
+superadded to those of the British district:--_Saurus_ (a tropical
+genus), _Aulopus_; _Congromuræna_, _Heteroconger_, _Myrus_,
+_Ophichthys_, _Muræna_.
+
+The Lophobranchs are more numerous in species and individuals than in
+the British district; and, besides _Syngnathus_ and _Nerophis_, several
+species of _Hippocampus_ are common. Also a few species of _Balistes_
+occur.
+
+_Myxine_ is lost in this district; whilst _Branchiostoma_ is abundant.
+
+3. The shore fishes of the _North American_ district consist, as on
+the eastern coasts of the North Atlantic, of northern and southern
+elements; but they are still more mixed with each other than on the
+European coasts, so that a boundary line cannot be drawn between
+them. The affinity to the fauna of the eastern shores is great,
+but almost entirely limited to the genera composing the fauna of
+the British district. British genera not found on the American
+coasts are--_Galeus_, _Scyllium_, _Chimæra_, _Mullus_, _Pagellus_,
+_Trigla_, _Trachinus_, _Zeus_, _Callionymus_. The southern elements
+of North America are rather derived from the West Indies, and
+have no special affinity to Mediterranean forms; very few of the
+non-British Mediterranean forms extend across the Atlantic; instead
+of a Mediterranean we find a West Indian element. Many of the British
+_species_ range across the Atlantic, and inhabit in an unchanged
+condition the northern parts of this district; and from the frequent
+occurrence of isolated specimens of other British species on the North
+American coast, we may presume that many more occasionally cross the
+Atlantic, but without being able to obtain a permanent footing.
+
+The genera peculiar to this district are few in number, and composed
+of very few species, viz. _Hemitripterus_, _Pammelas_, _Chasmodes_,
+_Cryptacanthodes_, and _Tautoga_.
+
+The close resemblance of what must be considered northern forms to
+those of Europe will be evident from the following list:--
+
+_Mustelus, Rhina, Torpedo, Raja, Trygon._
+
+_Labrax, Centropristis, Serranus; Pagrus, Chrysophrys; Sebastes,
+Hemitripterus; Cottus, Aspidophoroides; Uranoscopus; Micropogon,
+Pogonias, Sciæna; Trachurus, Pammelas; Cyclopterus, Liparis; Lophius;
+Anarrhichas, Chasmodes, Stichcæus, Centronotus, Cryptacanthodes,
+Zoarces._
+
+_Tautoga, Ctenolabrus._
+
+_Gadus, Merluccius, Phycis, Molva, Motella, Brosmius; Ophidium_ (one
+species, perhaps identical with a Mediterranean species); _Ammodytes;
+Hippoglossus, Hippoglossoides, Rhombus, Pleuronectes_.
+
+_Osmerus, Mallotus; Engraulis, Clupea; Conger._
+
+_Syngnathus--Myxine--Branchiostoma._
+
+West Indian genera, or at least genera which are more developed within
+the tropics, and which extend more or less northwards in the North
+American district, are:--
+
+_Pteroplatea_ (also in the Mediterranean).
+
+_Gerres, Dules (auriga), Lobotes, Ephippus; Sargus; Prionotus; Umbrina,
+Otolithus, Larimus; Sphyræna_ (Mediterr.); _Trichiurus_ (Mediterr.);
+_Elacate; Cybium, Trachynotus; Stromateus_ (Mediterr.); _Caranx_;
+_Batrachus_ (Mediterr.); _Malthe_.
+
+_Pseudorhombus_, _Solea_ (Mediterr.)
+
+_Saurus_ (Mediterr.); _Etrumeus, Albula, Elops, Megalops_.
+
+_Hippocampus_ (Mediterr.)
+
+_Balistes, Monacanthus._
+
+
+            B. SHORE FISHES OF THE TEMPERATE NORTH PACIFIC.
+
+This fauna shows a great affinity to that of the temperate North
+Atlantic, not only in including a considerable proportion of identical
+genera, and even of species, but also in having its constituent parts
+similarly distributed. However, our knowledge of the ichthyology of
+this fauna is by no means complete. Very few collections have been
+made in Northern Japan, and on the coasts farther north of it; and,
+again, the ichthyology of the coasts of Southern California is but
+little known. Southern Japan has been well searched, but very little
+attention has been paid to the extent of the northward range of the
+species. In collections made by Mr. Swinhoe at Chefoo, in lat. 37° N.,
+the proportions of temperate and tropical fishes were found to be about
+equal. Thus, the details of the distribution of the fishes of these
+shores have still to be worked out; nevertheless, three divisions may
+be recognised which, for the present, may be defined as follows:--
+
+1. The fishes of the north-western shores, to about 37° lat. N.,
+including the corresponding northern parts of Japan--_Kamtschatkan_
+district; this corresponds to the British district of the Atlantic.
+
+2. The fishes of Southern Japan and the corresponding shores of the
+continent of Asia, between 37° and 30° lat. N.--_Japanese_ district,
+which corresponds to the Mediterranean.
+
+3. The fishes of the eastern shores southwards to the latitude of
+San Francisco--_Californian_ district; this corresponds to the North
+American district of the Atlantic.
+
+Too little is known of the shore fishes of the coasts between San
+Francisco and the tropic to enable us to treat of it as a separate
+division.
+
+The Shore fishes of the North Pacific generally are composed of the
+following elements:--
+
+_a._ Arctic forms which extend into the Arctic Ocean, and the majority
+of which are also found in the British district.
+
+_b._ Peculiar forms limited to the North Pacific, like the
+_Heterolepidina_, _Embiotocidæ_, and certain Cottoid and Blennioid
+genera.
+
+_c._ Forms identical with fishes of the Mediterranean.
+
+_d._ Peculiar forms limited to the southern parts of Japan.
+
+_e._ Tropical forms which have entered the North Pacific from the
+south.
+
+       *       *       *       *       *
+
+1. The small list of fishes which we can assign to the _Kamtschatkan_
+district is due rather to the imperfect manner in which its fauna has
+been explored than to its actual poverty of fishes; thus, although we
+may be sure that sooner or later the small kinds of Dog-fishes of the
+British district will be found there also, at present we have positive
+knowledge of the occurrence of only two Chondropterygians, viz.
+_Chimæra_ and _Raja_. The species of the latter genus seem to be much
+less numerous than in the Atlantic.
+
+Of Acanthopterygians the following are known:--_Sebastes_; _Chirus_,
+_Agrammus_; _Podabrus_, _Blepsias_, _Cottus_, _Centridermichthys_,
+_Hemilepidotus_, _Agonus_; _Trichodon_; _Callionymus_; _Liparis_;
+_Dictyosoma_, _Stichæus_, _Centronotus_.
+
+Labroids are absent; they are clearly a type unable to endure great
+cold; of the Embiotocoids which represent them in the Pacific, one
+species only (a species of _Ditrema_) is known from this district.
+
+The Gadoids are, so far as we know at present, sparsely represented,
+viz. by isolated species of _Gadus_, _Motella_, and _Lotella_, the
+latter being an inhabitant of moderate depths rather than of the
+surface. _Hippoglossus_, _Pleuronectes_, and _Parophrys_, seem to occur
+everywhere at suitable localities.
+
+The Physostomes are nearly the same as in the British district, viz. a
+Smelt (_Hypomesus_), probably also the Arctic _Mallotus_, an Anchovy,
+several species of _Clupea_, and the Conger-eel. A very singular
+Salmonoid fish, _Salanx_, which is limited to the north-western
+Pacific, occurs in great abundance.
+
+Also, the Lophobranchs correspond in their development to those of the
+British district, _Nerophis_ being replaced by _Urocampus_.
+
+Neither Myxinoids nor _Branchiostoma_ have as yet been found.
+
+2. The _Japanese_ district is, like the Mediterranean, distinguished
+by a great variety of forms; some of them are peculiar to it (marked
+_J._ in the following list); others occur in the Mediterranean, though
+also in other districts (_M._) The resemblance to the Mediterranean
+is even greater than would appear from the following list of genera,
+inasmuch as a considerable number of species are identical in both
+districts. Three of the Berycoid genera have hitherto been found in
+the Japanese and Mediterranean districts only, and nowhere else.
+Another very singular fact is that some of the most characteristic
+genera, like _Mullus_, _Zeus_, _Callionymus_, _Centriscus_, inhabit
+the Mediterranean and Japanese districts, _but have never reached the
+opposite American coasts, either in the Atlantic or Pacific_; although,
+at least in the latter, the oceanic currents would rather favour
+than obstruct their dispersal in the direction towards America. Bold
+as the hypothesis may appear, we can only account for the singular
+distribution of these shore fishes by assuming that the Mediterranean
+and Japanese seas were in direct and open communication with each other
+within the period of the existence of the present Teleosteous Fauna.
+
+Gadoids have disappeared, or are represented by forms inhabiting
+moderate depths. Neither Myxine nor _Branchiostoma_ are known to have
+as yet been found.
+
+
+                   _List of Japanese Shore Fishes._
+
+_Chimæra_ (M.)
+
+_Galeus_ (M.), _Mustelus_ (M.), _Triacis_, _Scyllium_ (M.),
+_Crossorhinus_, _Pristiophorus_, _Cestracion_; _Rhina_ (M.);
+_Rhinobatus_ (M.), _Narcine_, _Raja_ (M.), _Trygon_ (M.), _Pteroplatea_
+(M.)
+
+_Percalabrax_ (J.), _Niphon_ (J.), _Centropristis_, _Anthias_ (M.),
+_Serranus_ (M.), _Apogon_ (M.), _Scombrops_ (J.), _Acropoma_, _Anoplus_
+(J.), _Pristipoma_ (M.), _Hapalogenys_ (J.), _Histiopterus_, _Velifer_
+(J.), _Dentex_ (M.), _Erythrichthys_--_Mullidæ_ (M.)--_Girella_,
+_Pagrus_ (M.), _Chrysophrys_ (M.)--_Chilodactylus_--_Sebastes_
+(M.), _Scorpæna_ (M.), _Aploactis_, _Trichopleura_,
+_Pelor_--_Monocentris_ (J.), _Hoplostethus_ (M.), _Beryx_ (M.),
+_Polymixia_ (M.)--_Platycephalus_, _Hoplichthys_ (J.), _Bembras_
+(J.), _Prionotus_, _Lepidotrigla_ (M.), _Trigla_ (M.), _Peristethus_
+(M.)--_Uranoscopus_ (M.), _Percis_, _Sillago_, _Latilus_.--_Sciæna_
+(M.), _Otolithus_--_Sphyræna_ (M.)--_Lepidopus_ (M.), _Trichiurus_
+(M.)--_Zeus_ (M.)--_Caranx_, _Trachurus_ (M.)--_Callionymus_
+(M.)--_Lophius_ (M.), _Halieuthæa_ (J.)--_Hoplognathus_--_Cepola_
+(M.)--_Centriscus_ (M.), _Fistularia_.
+
+_Heliastes_ (M.)--_Labrichthys_, _Duymæria_, _Platyglossus_, _Novacula_
+(M.), _Julis_ (M.), _Coris_ (M.)
+
+_Sirembo_ (J.)--_Motella_ (M.)--_Ateleopus_ (J.)
+
+_Pseudorhombus_, _Pleuronectes_ (M.), _Solea_ (M.), _Synaptura_ (M.)
+
+_Saurus_ (M.), _Harpodon_.--_Salanx_ (J.)--_Engraulis_ (M.), _Clupea_
+(M.), _Etrumeus_--_Conger_ (M.), _Congromuræna_ (M.), _Murænesox_ (M.),
+_Oxyconger_, _Myrus_ (M.), _Ophichthys_ (M.), _Muræna_ (M.)
+
+_Syngnathus_ (M.), _Hippocampus_ (M.), _Solenognathus_.
+
+_Triacanthus_, _Monacanthus_, _Ostracion_.
+
+3. The _Californian_ district includes a marked northern element, the
+principal constituents of which are identical with types occurring in
+the corresponding district of the Atlantic, viz. the North American,
+as exemplified by _Discoboli_, _Anarrhichas_, _Centronotus_, _Cottus_,
+_Hippoglossus_, _Clupea_ (_harengus_), etc. But it possesses also,
+in the greatest degree of development, some types almost peculiar
+to itself, as the _Heterolepidina_, some remarkable Cottoid and
+Blennioid genera, and more especially the Embiotocoids--viviparous
+Pharyngognaths--which replace the Labroids of the other hemisphere.
+Gadoids are much less numerous than in the North American district. The
+southern forms are but little known, but it may be anticipated that,
+owing to the partial identity of the Faunæ of the two coasts of the
+Isthmus of Panama, a fair proportion of West Indian forms will be found
+to have entered this district from the south. The following are the
+principal genera:--
+
+_Chimœra_, _Galeus_, _Mustelus_, _Triacis_, _Cestracion_, _Rhina_,
+_Raja_.
+
+_Serranus_; _Chirus_, _Ophiodon_, _Zaniolepis_; _Sebastes_;
+_Nautichthys_, _Scorpœnichthys_, _Cottus_, _Centridermichthys_,
+_Hemilepidotus_, _Artedius_, _Prionotus_, _Agonus_; _Cyclopterus_,
+_Liparis_; _Anarrhichas_, _Neoclinus_, _Cebidichthys_, _Stichœus_,
+_Centronotus_, _Apodichthys_; _Psychrolutes_; _Auliscops_.
+
+_Embiotocidœ_.
+
+_Gadus_. _Hippoglossus_, _Psettichthys_, _Citharichthys_,
+_Paralichthys_, _Pleuronectes_, _Parophrys_.
+
+_Osmerus_, _Thaleichthys_, _Hypomesus_; _Engraulis_, _Clupea_.
+
+_Syngnathus_.
+
+
+                      III.--THE EQUATORIAL ZONE.
+
+As we approach the Tropic from the north, the tribes characteristic
+of the Arctic and Temperate zones become scarcer, and disappear
+altogether: to be replaced by the greater variety of Tropical types.
+Of Chondropterygians, the _Chimœridœ_, _Spinacidœ_, _Mustelus_, and
+_Raja_, do not pass the Tropic, or appear in single species only;
+and of Teleosteans, the _Berycidæ_, _Pagrus_, the _Heterolepidina_,
+_Cottus_ and allied genera, _Lophius_, _Anarrhichas_, _Stichæus_,
+_Lepadogaster_, _Psychrolutes_, _Centriscus_, _Notacanthus_, the
+_Labridæ_ and _Embiotocidæ_, the _Lycodidæ_, _Gadidæ_, and marine
+_Salmonidæ_ disappear either entirely, or retire from the shores and
+surface into the depths of the ocean.
+
+With regard to variety of forms, as well as to number of individuals,
+this zone far surpasses either of the temperate zones; in this
+respect, the life in the sea is as that on the land. Coast fishes
+are not confined to the actual coast-line, but abound on the
+coral reefs, with which some parts of the Atlantic and Pacific
+are studded, and many of which are submerged below the water. The
+abundance of animal and vegetable life which flourishes on them
+renders them the favourite pasture-grounds for the endless variety of
+coral-fishes (_Squamipinnes_, _Acronuridæ_, _Pomacentridæ_, _Julidæ_,
+_Plectognathi_, etc.), and for the larger predatory kinds. The colours
+and grotesque forms of the Fishes of the Tropics have justly excited
+the admiration of the earliest observers. Scarlet, black, blue, pink,
+red, yellow, etc., are arranged in patterns of the most bizarre
+fashion, mingling in spots, lines, bands; and reminding us of the words
+of Captain Cook when describing the coral-reefs of Palmerston Island:
+“The glowing appearance of the Mollusks was still inferior to that of
+the multitude of fishes that glided gently along, seemingly with the
+most perfect security. The colours of the different sorts were the most
+beautiful that can be imagined--the yellow, blue, red, black, etc., far
+exceeding anything that art can produce. Their various forms, also,
+contributed to increase the richness of this sub-marine grotto, which
+could not be surveyed without a pleasing transport.”
+
+Of Chondropterygians the _Scylliidæ_, _Pristis_ (Saw-fishes),
+_Rhinobatidæ_, and _Trygonidæ_ attain to the greatest development.
+Of Acanthopterygians _Centropristis_, _Serranus_, _Plectropoma_,
+_Mesoprion_, _Priacanthus_, _Apogon_, _Pristipoma_, _Hæmulon_,
+_Diagramma_, _Gerres_, _Scolopsis_, _Synagris_, _Cæsio_, _Mullidæ_,
+_Lethrinus_, _Squamipinnes_, _Cirrhites_, some genera of _Scorpænidæ_,
+_Platycephalus_, _Sciænidæ_, _Sphyræna_, _Caranx_ _Equula_,
+_Callionymus_, _Teuthis_, _Acanthurus_, _Naseus_, are represented by
+numerous species; and the majority of these genera and families are
+limited to this zone. Of Pharyngognaths the _Pomacentridæ_, _Julidina_,
+and _Scarina_, are met with near every coral formation in a living
+condition. Of Gadoids, a singular minute form, _Bregmaceros_, is almost
+the only representative, the other forms belonging to deep water, and
+rarely ascending to the surface. Flat-fishes (_Pleuronectidæ_) are
+common on sandy coasts, and the majority of the genera are peculiar
+to the Tropics. Of _Physostomi_ only the _Saurina_, _Clupeidæ_, and
+_Murænidæ_ are represented, the _Clupeidæ_ being exceedingly numerous
+in individuals, whilst the _Murænidæ_ live more isolated, but show a
+still greater variety of species. Lophobranchii and Sclerodermi are
+generally distributed. Branchiostoma has been found on several coasts.
+
+Geographically it is convenient to describe the Coast fauna of the
+tropical Atlantic separately from that of the Indo-Pacific ocean. The
+differences between them, however, are far less numerous and important
+than between the freshwater or terrestrial faunæ of continental
+regions. The majority of the principal types are found in both, many of
+the species being even identical; but the species are far more abundant
+in the Indo-Pacific than in the Atlantic, owing to the greater extent
+of the archipelagoes in the former. But for the broken and varied
+character of the coasts of the West Indies, the shores of the tropical
+Atlantic would, by their general uniformity, afford but a limited
+variety of conditions to the development of specific and generic
+forms, whilst the deep inlets of the Indian ocean, with the varying
+configuration of their coasts, and the different nature of their
+bottom, its long peninsulas, and its archipelagoes, and the scattered
+islands of the tropical Pacific, render this part of the globe the
+most perfect for the development of fish-life. The fishes of the
+Indian and Pacific oceans (between the Tropics) are almost identical,
+and the number of species ranging from the Red Sea and east coast of
+Africa to Polynesia, even to its westernmost islands, is very great
+indeed. However, this Indo-Pacific fauna does not reach the Pacific
+coast of South America. The wide space devoid of islands, east of the
+Sandwich Islands and the Marquesas group, together with the current
+of cold water which sweeps northwards along the South American coast,
+has proved to be a very effectual barrier to the eastward extension
+of the Indo-Pacific fauna of coast fishes; and, consequently, we find
+an assemblage of fishes on the American coast and at the Galapagoes
+Islands, sufficiently distinct to constitute a distinct zoological
+division.
+
+The following list, which contains only the principal genera and groups
+of coast fishes, will give an idea of the affinity of the tropical
+Atlantic and Indo-Pacific:--[28]
+
+                                    Trop.-Atl.  Indo-Pac.
+
+    Scylliidæ                           --         13
+    _Pristis_                            3          4
+    _Rhinobatidæ_                        4          8
+    _Torpedinidæ_                        1          8
+    _Trygonidæ_                         14         24
+    _Etelis_                             1          1
+    _Aprion_                            --          1
+    _Apsilus_                            1         --
+    _Centropristis_                     15         --
+    _Anthias_                            4          5
+    _Serranus_                          30         85
+    _Plectropoma_                       11          5
+    _Grammistes_                        --          2
+    _Rhypticus_                         3          --
+    _Diploprion_                       --           1
+    _Myriodon_                         --           1
+    _Mesoprion_                        15          50
+    _Priacanthus_                       4          12
+    _Apogon_ and _Chilodipterus_        2          75
+    _Pristipoma_                       12          14
+    _Hæmulon_                          15          --
+    _Diagramma_                        --          30
+    _Gerres_                           12          16
+    _Scolopsis_                        --          20
+    Dentex and _Symphorus_             --           7
+    _Synagris_ and _Pentapus_          --          24
+    _Cæsio_                            --          12
+    Mullidæ                             5          22
+    Sargus                              7           2
+    _Lethrinus_                         1          18
+    _Chrysophrys_                       1           7
+    _Pimelepterus_                      1           5
+    _Squamipinnes_                     13         110
+    _Toxotes_                          --           2
+    _Cirrhites_                        --          20
+    Scorpænidæ                          2          65
+    _Myripristis_                       3          15
+    _Holocentrum_                       6          25
+    _Platycephalus_                    --          25
+    Prionotus                           1          --
+    Trigla                             --           4
+    Peristethus                         2           6
+    Uranoscopina                        2           8
+    _Champsodon_                       --           1
+    _Percis_                           --          10
+    _Sillago_                          --           5
+    Latilus                             1           2
+    _Opisthognathus_                    2           5
+    _Pseudochromis_                    --           8
+    _Cichlops_ and _Pseudoplesiops_    --           2
+    _Sciænidæ_                         44          43
+    _Sphyræna_                          1          10
+    _Trichiuridæ_                       6           5
+    _Caranx_                           20          60
+    _Chorinemus_                        4           7
+    _Trachynotus_                       6           4
+    _Psettus_                           1           2
+    _Platax_                           --           7
+    _Zanclus_                          --           1
+    _Equula_ and _Gazza_               --          20
+    _Teuthis_                          --          30
+    _Acanthurus_                        3          42
+    _Naseus_                           --          12
+    _Kurtidæ_                           1           6
+    _Gobiodon_                         --           7
+    Callionymus                        --          17
+    _Batrachidæ_                        5           4
+    _Tetrabrachium_                    --           1
+    Malthe                              1          --
+    _Petroscirtes_                     --          30
+    Clinus                              6          --
+    _Dactyloscopus_                     1          --
+    _Malacanthus_                       1           2
+    Cepola                             --           1
+    Gobiesocidæ                         5           1
+    _Amphisile_                        --           3
+    _Fistulariidæ_                      3           3
+    _Pomacentridæ_                     17         120
+    _Lachnolæmus_                       1          --
+    _Julidina_                         36         190
+    Pseudodax                          --           1
+    _Scarina_                          21          65
+    Pseudophycis                       --           1
+    _Bregmaceros_                      --           1
+    Ophidiidæ                           3           7
+    _Fierasfer_                        --           6
+    Pleuronectidæ                      21          56
+    _Saurina_                           5           9
+    Clupeidæ.                          33          84
+    _Chirocentrus_                     --           1
+    _Murænidæ_                         47         130
+    _Pegasus_                          --           3
+    _Solenostoma_                      --           2
+    Syngnathidæ                         7          41
+    _Sclerodermi_                      16          67
+    Gymnodontes                        23          40
+
+
+              A. _Shore Fishes of the Tropical Atlantic._
+
+The boundaries of the tropical Atlantic extend zoologically a few
+degrees beyond the Northern and Southern Tropics, but as the mixture
+with the types of the temperate zone is very gradual, no distinct
+boundary line can be drawn between the tropical and temperate faunæ.
+
+Types, almost exclusively limited to it, and not found in the
+Indo-Pacific, are few in number, as _Centropristis_, _Rhypticus_,
+_Hæmulon_, _Malthe_. A few others preponderate with regard to the
+number of species, as _Plectropoma_, _Sargus_, _Trachynotus_,
+_Batrachidæ_, and _Gobiesocidæ_. The Sciænoids are equally represented
+in both oceans. All the remainder are found in both; but in the
+minority in the Atlantic, where they are sometimes represented by one
+or two species only (for instance, _Lethrinus_).
+
+
+         B. _Shore Fishes of the Tropical Indo-Pacific Ocean._
+
+The ichthyological boundaries of this part of the tropical zone may be
+approximately given as 30° of lat. N. and S.; on the Australian coasts
+it should probably be placed still farther south, viz., to 34°; it
+includes, as mentioned above, the Sandwich Islands, and all the islands
+of the South Sea, but not the American coasts.
+
+Some eighty genera of Shore fishes are peculiar to the Indo-Pacific,
+but the majority consists of one or a few species only; comparatively
+few have a plurality of species, as _Diagramma_, _Lethrinus_, _Equula_,
+_Teuthis_, _Amphiprion_, _Dascyllus_, _Choerops_, _Chilinus_,
+_Anampses_, _Stethojulis_, _Coris_, _Coilia_.
+
+The Sea-perches, large and small, which feed on Crustaceans and other
+small fishes, and the coral-feeding Pharyngognaths are the types which
+show the greatest generic and specific variety in the Indo-Pacific.
+Then follow the _Squamipinnes_ and _Murænidæ_, the _Clupeidæ_ and
+_Carangidæ_ families in which the variety is more that of species than
+of genus. The _Scorpænidæ_, _Pleuronectidæ_, _Acronuridæ_, _Sciænidæ_,
+_Syngnathidæ_, and _Teuthyes_, are those which contribute the next
+largest contingents. Of shore-loving Chondropterygians the _Scylliidæ_
+and _Trygonidæ_ only are represented in moderate numbers, though they
+are more numerous in this ocean than in any other.
+
+
+     C. _Shore Fishes of the Pacific Coasts of Tropical America_.
+
+As boundaries within which this fauna is comprised, may be indicated
+30° lat. N. and S., as in the Indo-Pacific. Its distinction from the
+Indo-Pacific lies in the almost entire absence of coral-feeding fishes.
+There are scarcely any Squamipinnes, Pharyngognaths or Acronuridæ,
+and the Teuthyes are entirely absent. The genera that remain are such
+as are found in the tropical zone generally, but the species are
+entirely different from those of the Indo-Pacific. They are mixed with
+a sprinkling of peculiar genera, consisting of one or two species,
+like _Discopyge_, _Hoplopagrus_, _Doydixodon_, but they are too few in
+number to give a strikingly peculiar character to this fauna.
+
+The Three districts are distinguishable:--
+
+a. _Central American district_, in which we include, for the present,
+Lower California, shows so near an affinity to the tropical Atlantic
+that, if it were not separated from it by the neck of land uniting
+the two American Continents, it would most assuredly be regarded as
+a portion of the Fauna of the tropical Atlantic. With scarcely any
+exceptions the genera are identical, and of the species found on the
+Pacific side nearly one-half have proved to be the same as those of the
+Atlantic. The explanation of this fact has been found in the existence
+of communications between the two oceans by channels and straits
+which must have been open till within a recent period. The isthmus of
+Central America was then partially submerged, and appeared as a chain
+of islands similar to that of the Antilles; but as the reef-building
+corals flourished chiefly north and east of those islands, and were
+absent south and west of them, reef-fishes were excluded from the
+Pacific shores when the communications were destroyed by the upheaval
+of the land.
+
+_b_. The _Galapagoes district_ received its coast fauna principally
+from the Central American district, a part of the species being
+absolutely the same as on the coast of the Isthmus of Panama, or as
+in the West Indies. Yet the isolation of this group has continued
+a sufficiently long period to allow of the development of a number
+of distinct species of either peculiarly Atlantic genera (such as
+_Centropristis_, _Rhypticus_, _Gobiesox_, _Prionotus_), or at least
+tropical genera (such as _Chrysophrys_, _Pristipoma_, _Holacanthus_,
+_Caranx_, _Balistes_). A few other types from the Peruvian coast
+(_Doydixodon_), or even from Japan (_Prionurus_), have established
+themselves in this group of islands. A species of _Cestracion_ has also
+reached the Galapagoes, but whether from the south, north, or west,
+cannot be determined.
+
+The presence of the Atlantic fauna on the Pacific side is felt still
+farther west than the Galapagoes, some Atlantic species having
+reached the Sandwich Islands, as _Chætodon humeralis_ and _Blennius
+brevipinnis_.
+
+c. The _Peruvian district_ possesses a very limited variety of
+shore fishes, which belong, with few exceptions, like _Discopyge_,
+_Hoplognathus_, _Doydixodon_, to genera distributed throughout the
+tropical zone, or even beyond it. But the species, so far as they are
+known at present, are distinct from those of the Indo-Pacific, as well
+as of the tropical Atlantic; and therefore this district cannot be
+joined either to the Central American or the Galapagoes.
+
+
+                   IV.--THE SOUTHERN TEMPERATE ZONE.
+
+This zone includes the coasts of the southern extremity of Africa, from
+about 30° lat. S., of the south of Australia with Tasmania, of New
+Zealand, and the Pacific and Atlantic coasts of South America between
+30° and 50° lat. S.
+
+The most striking character of this fauna is the reappearance
+of types inhabiting the corresponding latitudes of the Northern
+Hemisphere, and not found in the intervening tropical zone. This
+interruption of the continuity in the geographical distribution
+of Shore-fishes is exemplified by species as well as genera, for
+instance--_Chimæra monstrosa_, _Galeus canis_, _Acanthias vulgaris_,
+_Acanthias blainvillii_, _Rhina squatina_, _Zeus faber_, _Lophius
+piscatorius_, _Centriscus scolopax_, _Engraulis encrasicholus_,
+_Clupea sprattus_, _Conger vulgaris_. Instances of genera are still
+more numerous--_Cestracion_, _Spinax_, _Pristiophorus_, _Raja_;
+_Callanthias_, _Polyprion_, _Histiopterus_, _Cantharus_, _Box_,
+_Girella_, _Pagellus_, _Chilodactylus_, _Sebastes_, _Aploactis_,
+_Agonus_, _Lepidopus_, _Cyttus_, _Psychrolutidæ_, _Notacanthus_;
+_Lycodes_, _Merluccius_, _Lotella_, _Phycis_, _Motella_; _Aulopus_;
+_Urocampus_, _Solenognathus_; _Myxine_.
+
+Naturally, where the coasts of the tropical zone are continuous with
+those of the temperate, a number of tropical genera enter the latter,
+and genera which we have found between the tropics as well as in the
+temperate zone of the Northern Hemisphere, extend in a similar manner
+towards the south. But the truly tropical forms are absent; there
+are no _Squamipinnes_, scarcely any _Mullidæ_, no _Acronuri_, no
+_Teuthyes_, no _Pomacentridæ_ (with a single exception on the coast of
+Chili), only one genus of _Julidina_, no _Scarina_, which are replaced
+by another group of Pharyngognaths, the _Odacina_. The _Labrina_,
+so characteristic of the temperate zone of the Northern Hemisphere,
+reappear in a distinct genus (_Malacopterus_) on the coast of Juan
+Fernandez.
+
+The family of _Berycidæ_, equally interesting with regard to their
+distribution in time and in space, consists of temperate and tropical
+genera. The genus by which this family is represented in the southern
+temperate zone (_Trachichthys_) is much more nearly allied to the
+northern than to the tropical genera.
+
+The true _Cottina_ and _Heterolepidina_ (forms with a bony stay of the
+præoperculum, which is generally armed) have not crossed the tropical
+zone; they are replaced by fishes extremely similar in general form,
+and having the same habits, but lacking that osteological peculiarity.
+Their southern analogues belong chiefly to the family _Trachinidæ_, and
+are types of genera peculiar to the Southern Hemisphere.
+
+The _Discoboli_ of the Northern Hemisphere have likewise not penetrated
+to the south, where they are represented by _Gobiesocidæ_. These two
+families replace each other in their distribution over the globe.
+
+Nearly all the _Pleuronectidæ_ (but they are not numerous) belong to
+distinct genera, some, however, being remarkably similar in general
+form to the northern _Pleuronectes_.
+
+With Gadoids _Myxinidæ_ reappear, one species being extremely similar
+to the European Myxine. _Bdellostoma_ is a genus peculiar to the
+southern temperate zone.
+
+As in the northern temperate zone, so in the southern, the number of
+individuals and the variety of forms is much less than between the
+tropics. This is especially apparent on comparing the numbers of
+species constituting a genus. In this zone genera composed of more than
+ten species are the exception, the majority having only from one to
+five.
+
+The proportion of genera limited to this zone is rather high; they
+will be indicated under the several districts, which we distinguish on
+geographical rather than zoological grounds.
+
+1. The _Cape of Good Hope_ district.
+
+The principal genera found in this district are the following (those
+limited to the entire zone being marked with a single (*) and those
+peculiar to this district with a double (**) asterisk):--
+
+_Chimæra_, *_Callorhynchus_, _Galeus_, **_Leptocarcharias_, _Scyllium_,
+_Acanthias_, _Rhinobatus_, _Torpedo_, _Narcine_, _Astrape_, _Raja_.
+
+_Serranus_, _Dentex_, _Pristipoma_; _Cantharus_, _Box_, **_Dipterodon_,
+_Sagrus_, _Pagrus_, _Pagellus_, _Chrysophrys_; *_Chilodactylus_;
+_Sebastes_, *_Agriopus_; _Trigla_; _Sphyræna_; _Lepidopus_,
+_Thyrsites_; _Zeus_; _Caranx_; _Lophius_; _Clinus_ (10 species),
+_Cristiceps_; **_Chorisochismus_.
+
+*_Halidesmus_, *_Genypterus_, _Motella_.
+
+_Syngnathus_.--*_Bdellostoma_.
+
+This list contains many northern forms, which in conjunction with
+the peculiarly southern types (_Callorhynchus_, _Chilodactylus_,
+_Agriopus_, _Clinus_, _Genypterus_, _Bdellostoma_) leave no doubt
+that this district belongs to the southern temperate zone, whilst the
+Freshwater fishes of South Africa are members of the tropical fauna.
+Only a few (_Rhinobatus_, _Narcine_, _Astrape_, and _Sphyræna_) have
+entered from the neighbouring tropical coasts. The development of
+Sparoids is greater than in any of the other districts of this zone,
+and may be regarded as one of its distinguishing features.
+
+2. The _South Australian_ district comprises the southern coasts of
+Australia (northwards, about to the latitude of Sydney), Tasmania,
+and New Zealand. It is the richest in the southern temperate zone,
+partly in consequence of a considerable influx of tropical forms on the
+eastern coast of Australia, where they penetrate farther southwards
+than should have been expected from merely geographical considerations;
+partly in consequence of the thorough manner in which the ichthyology
+of New South Wales and New Zealand has been explored. On the other
+hand, the western half of the south coast of Australia is still almost
+a _terra incognita_.
+
+The shore-fishes of New Zealand are not so distinct from those of
+south-eastern Australia as to deserve to be placed in a separate
+district. Beside the genera which enter this zone from the Tropics,
+and which are more numerous on the Australian coast than on that of
+New Zealand, and beside a few very local genera, the remainder are
+identical. Many of the South Australian species, besides, are found
+also on the coasts of New Zealand. The principal points of difference
+are the extraordinary development of Monacanthus on the coast of South
+Australia, and the apparently total absence in Australia of Gadoids,
+which in the New Zealand Fauna are represented by six genera.
+
+
+_Shore-fishes of the South Australian district._
+
+
+                                       South Australia
+                                        and Tasmania.      New Zealand.
+    *Callorhynchus (antarcticus).             1                1
+    Galeus (canis)                            1                1
+    Scyllium  ...                             2                1
+    **Parascyllium                            1               --
+    Crossorhinus                              1               --
+    Cestracion ...                            2                1
+    Mustelus (antarcticus)                    1                1
+    Acanthias (vulgaris and blainvillii)      2                1
+    Rhina                                     1               --
+    Pristiophorus                             1               --
+    **Trygonorhina (fasciata)                 1                1
+      Rhinobatus                              1                1
+      Torpedo                                --                1
+      Narcine                                 1               --
+      Raja                                    3                1
+      Trygon (Urolophus)                      3                2
+    **Enoplosus                               1               --
+      Anthias (richardsonii)                  1                1
+      Callanthias                             1               --
+      Serranus                                x[29]           --
+      Plectropoma                             4               --
+    **Lanioperca                              1               --
+    **Arripis                                 3                1
+      Histiopterus                            1               --
+      Erythrichthys                          --                1
+     *Haplodactylus                           2                2
+      Girella                                 4               --
+    **Tephræops                               1               --
+      Pagrus                                  1                1
+     *Scorpis                                 2                1
+    **Atypichthys                             1               --
+    **Trachichthys                           --                1
+    **Chironemus                              1                1
+    **Holoxenus                               1               --
+      Chilodactylus                           9                4
+    **Nemadactylus                            1               --
+    **Latris                                  2                2
+      Scorpæna                                4                2
+    **Glyptauchen                             1               --
+      Centropogon                             2               --
+     *Agriopus                                1                1
+     *Aploactis                               1               --
+    **Pentaroge                               1               --
+      Platycephalus                           5               --
+      Lepidotrigla                            3                1
+      Trigla                                  3                1
+    Anema                                     --               1
+    **Crapatalus                              --               1
+    **Kathetostoma                            1                2
+    **Leptoscopus                             1                3
+      Percis                                  2                1
+     *Aphritis                                1               --
+      Sillago                                 2               --
+     *Bovichthys                              1                1
+     *Notothenia                              --               1
+      Sphyræna                                1               --
+      Lepidopus                               --               1
+      Trichiurus                              1               --
+      Thyrsites                               1                1
+    **Platystethus                           --                2
+      Zeus (faber)                            1                1
+      Cyttus                                  1                1
+      Trachurus (trachurus)                   1                1
+      Caranx                                  x                2
+     *Seriolella                             --                1
+      Pempheris                               1               --
+      Callionymus                             3               --
+      Batrachus                               1               --
+    **Brachionichthys                         2               --
+    **Saccarius                              --                1
+      Clinus                                  1                1
+    **Lepidoblennius                          1               --
+      Cristiceps and Tripterygium             4                5
+    **Patæcus                                 3               --
+    **Acanthoclinus                          --                1
+    **Diplocrepis                            --                1
+    **Crepidogaster                           3                1
+    **Trachelochismus                        --                1
+    **Neophrynichthys                        --                1
+      Centriscus                              2                1
+      Notacanthus (sexspinis)                 1                1
+    **Labrichthys                             8                2
+    **Odax                                    5                1
+    Coridodax                                --                1
+    **Olistherops                             1               --
+    **Siphonognathus                          1               --
+      Gadus                                  --                1
+      Merluccius                             --                1
+      Lotella                                --                1
+    **Pseudophycis                           --                1
+      Motella                                --                1
+      Bregmaceros                            --                1
+     *Genypterus                              1                1
+    **Lophonectes                             1               --
+    **Brachypleura                           --                1
+      Pseudorhombus                          --                1
+    **Ammotretis                              1                1
+    **Rhombosolea                             3                3
+    **Peltorhamphus                          --                1
+      Solea                                   1               --
+      Aulopus                                 1               --
+      Gonorhynchus (greyi)                    1                1
+      Engraulis (encrasicholus)               1                1
+      Clupea                                  1                1
+    **Chilobranchus                           1               --
+      Conger (vulgaris)                       1                1
+      Ophichthys                              1                1
+      Murænichthys                            1               --
+      Congromuræna                           --                1
+      Syngnathus                              5                2
+      Ichthyocampus                          --                1
+    **Nannocampus                             1               --
+      Urocampus                               1               --
+    **Stigmatophora                           2                1
+      Solenognathus                           2                1
+    **Phyllopteryx                            2               --
+      Monacanthus                            15                1
+      Ostracion                               3                1
+     *Bdellostoma                            --                1
+      Branchiostoma                           1                1
+
+3. The coast-line of the _Chilian district_ extends over 20
+degrees of latitude only, and is nearly straight. In its northern and
+warmer parts it is of a very uniform character, and exposed to high and
+irregular tides, and to remarkable and sudden changes of the levels of
+land and water, which must seriously interfere with fishes living and
+propagating near the shore. No river of considerable size interrupts
+the monotony of the physical conditions, to offer an additional element
+in favour of the development of littoral animals. In the southern
+parts, where the coast is lined with archipelagoes, the climate is too
+severe for the majority of fishes. All these conditions combine to
+render this district comparatively poor as regards variety of Shore
+fishes, as will be seen from the following list:--
+
+*Callorhynchus; Scyllium, Acanthias, Spinax; Urolophus.
+
+Serranus, Plectropoma, Polyprion, Pristipoma, Erythrichthys;
+*Haplodactylus; *Scorpis; Chilodactylus, **Mendosoma; Sebastes,
+*Agriopus; Trigla, Agonus; *Aphritis, *Eleginus, Pinguipes, Latilus,
+Notothenia (1 sp.) Umbrina; Thyrsites; Trachurus, Caranx, *Seriolella;
+Porichthys; **Myxodes, Clinus; Sicyases, Gobiesox.
+
+Heliastes; **Malacopterus; *Labrichthys.
+
+Merluccius; *Genypterus; Pseudorhombus.
+
+Engraulis, Clupea; Ophichthys, Muræna.
+
+Syngnathus.--*Bdellostoma.
+
+Of these genera six only are not found in other districts of this
+zone. Three are peculiar to the Chilian district; _Porichthys_
+and _Agonus_ have penetrated so far southwards from the Peruvian
+and Californian districts; and _Polyprion_ is one of those
+extraordinary instances in which a very specialised form occurs at
+almost opposite points of the globe, without having left a trace of
+its previous existence in, or of its passage through, the intermediate
+space.
+
+4. The _Patagonian district_ is, with the exception of the
+neighbourhood of the mouth of the Rio de la Plata, almost unknown.
+In that estuary occur _Mustelus vulgaris_, two _Raja_, two _Trygon_,
+several Sciænoids, _Paropsis signata_ and _Percophis brasilianus_
+(two fishes peculiar to this coast), _Prionotus punctatus_, _Læmonema
+longifilis_ (a Gadoid), a _Pseudorhombus_, two Soles, _Engraulis
+olidus_, a _Syngnathus_, _Conger vulgaris_, and _Ophichthys ocellatus_;
+and if we notice the occurrence of a _Serranus_ and _Caranx_, of
+_Aphritis_ and _Pinguipes_, and of two or three _Clupea_, we shall have
+enumerated all that is known of this fauna. The fishes of the southern
+part, viz. the coast of Patagonia proper, southwards to Magelhæn’s
+Straits, are unknown; which is the more to be regretted, as it is most
+probably the part in which the characteristic types of this district
+are most developed.
+
+
+               V.--SHORE FISHES OF THE ANTARCTIC OCEAN.
+
+To this fauna we refer the shore fishes of the southernmost extremity
+of South America, from 50° lat. S., with Tierra del Fuego and the
+Falkland Islands, and those of Kerguelen’s Land, with Prince Edward’s
+Island. No fishes are known from the other oceanic islands of these
+latitudes.
+
+In the Southern Hemisphere surface fishes do not extend so far towards
+the Pole as in the Northern; none are known from beyond 60° lat. S.,
+and the Antarctic Fauna, which is analogous to the Arctic Fauna,
+inhabits coasts more than ten degrees nearer to the equator. It is
+very probable that the shores between 60° and the Antarctic circle
+are inhabited by fishes sufficiently numerous to supply part of the
+means of subsistence for the large Seals which pass there at least
+some season of the year, but hitherto none have been obtained by
+naturalists; all that the present state of our knowledge justifies us
+in saying is, that the general character of the Fauna of Magelhæn’s
+Straits and Kerguelen’s Land is extremely similar to that of Iceland
+and Greenland.
+
+As in the arctic Fauna, Chondropterygians are scarce, and represented
+by _Acanthias vulgaris_ and species of _Raja_. _Holocephali_ have not
+yet been found so far south, but _Callorhynchus_, which is not uncommon
+near the northern boundary of this fauna, will prove to extend into it.
+
+As to Acanthopterygians, _Cataphracti_ and _Scorpænidæ_ are
+represented as in the arctic Fauna, two of the genera (_Sebastes_ and
+_Agonus_) being identical. The _Cottidæ_ are replaced by six genera
+of _Trachinidæ_, remarkably similar in form to arctic types; but
+_Discoboli_ and the characteristic Arctic Blennioids are absent.
+
+Gadoid Fishes reappear, but are less developed; as usual they are
+accompanied by _Myxine_. The reappearance of so specialised a genus as
+_Lycodes_ is most remarkable. Flat-fishes are scarce as in the North,
+and belong to peculiar genera.
+
+Physostomes are probably not entirely absent, but hitherto none have
+been met with so far south. Lophobranchs are scarce, as in the Arctic
+zone; however, it is noteworthy that a peculiar genus, with persistent
+embryonic characters (_Protocampus_), is rather common on the shores of
+the Falkland Islands.
+
+The following are the genera known from this zone. Those with a
+single asterisk (*) are known to extend into the Temperate zone, but
+not beyond it; those with a double asterisk (**) are limited to the
+Antarctic shores:--
+
+                      Magelhæn’s and
+                        Falkland.       Kerguelen.
+
+      Acanthias vulgaris    1              --
+      Raja                  1               2
+      Psammobatis           1              --
+      Sebastes              1              --
+    **Zanclorhynchus       --               1
+     *Agriopus              1              --
+      Agonus                1              --
+     *Aphritis              1              --
+     *Eleginus              1              --
+    **Chænichthys           1               1
+     *Bovichthys            2              --
+     *Notothenia            8               7
+    **Harpagifer            1               1
+      Lycodes               4              --
+    **Magnea                1              --
+      Lotella               1              --
+      Merluccius            1              --
+    **Lepidopsetta         --               1
+    **Thysanopsetta         1              --
+      Syngnathus            1              --
+    **Protocampus           1              --
+      Myxine                1              --
+                          ---             ---
+                           31              13
+                          ===             ===
+
+  [Illustration: Fig. 108.--_Chænichthys rhinoceratus_, shores
+  of the Antarctic Ocean.]
+
+
+
+
+                              CHAPTER XX.
+
+                    DISTRIBUTION OF PELAGIC FISHES.
+
+
+Pelagic Fishes,--that is, fishes inhabiting the surface of mid-ocean
+(see p. 255), belong to various orders, viz. Chondropterygians,
+Acanthopterygians, Physostomes, Lophobranchs, and Plectognaths. But
+neither Anacanths nor Pharyngognaths contribute to this series of the
+Marine Fauna. The following genera and families are included in it:--
+
+CHONDROPTERYGII: Carcharias, Galeocerdo, Thalassorhinus, Zygæna,
+Triænodon, Lamnidæ, Rhinodon, Notidanidæ, Læmargus, Euprotomicrus,
+Echinorhinus, Isistius; Myliobatidæ.
+
+ACANTHOPTERYGII: Dactylopterus, Micropteryx, Scombrina, Gastrochisma,
+Nomeus, Centrolophus, Coryphænina, Seriola, Temnodon, Naucrates,
+Psenes, Xiphiidæ, Antennarius.
+
+PHYSOSTOMI: Sternoptychidæ, Scopelus, Astronesthes, Scombresocidæ
+(majority).
+
+LOPHOBRANCHII: Hippocampus.
+
+PLECTOGNATHI: Orthagoriscus, and some other Gymnodonts.
+
+Pelagic fishes differ much from one another in their mode of life.
+The majority are excellent swimmers, which not only can move with
+great rapidity, but also are possessed of great powers of endurance,
+and are thus enabled to continue their course for weeks, apparently
+without the necessity of rest: such are many Sharks, Scombroids,
+Dolphins, Pilot-fish, Sword-fishes. In some, as in _Dactylopterus_
+and _Exocoetus_, the ability of taking flying leaps out of the water
+is superadded to the power of swimming (Flying-fishes). But in others
+the power of swimming is greatly reduced, as in _Antennarius_,
+_Hippocampus_, and Gymnodonts; they frequent places in the ocean
+covered with floating seaweed, or drift on the surface without
+resistance, at the mercy of wind and current. The _Echeneis_ or
+Sucking-fishes attach themselves to other large fish, ships, or
+floating objects, and allow themselves to be carried about, unless
+change of climate or want of food obliges them to abandon their
+temporary carrier. Finally, another class of Pelagic fishes come to
+the surface of the ocean during the night only; in the day time they
+descend to some depth, where they are undisturbed by the rays of the
+sun or the agitation of the surface-water: such are _Brama_, the
+_Sternoptychidæ_, _Scopelus_, _Astronesthes_; fishes, the majority of
+which are provided with those extraordinary luminary organs that we
+find so much developed in the true Deep-sea fishes. Indeed, this last
+kind of Pelagic fishes forms a passage to the Deep-sea forms.
+
+Pelagic fishes, like shore fishes, are most numerous in the
+Tropical Zone; and, with few exceptions (_Echinorhinus_, _Psenes_,
+_Sternoptychidæ_, _Astronesthes_), the same genera are represented
+in the tropical Atlantic as well as in the Indo-Pacific. The number
+of identical species occurring in both these oceans is great, and
+probably still greater than would appear from systematic lists, in
+which there are retained many specific names that were given at a time
+when species were believed to have a very limited range. The Pelagic
+fauna of the tropics gradually passes into that of the temperate
+zones, only a few genera, like _Cybium_, _Psenes_, _Antennarius_,
+being almost entirely confined to the tropics. All the other tropical
+genera range into the temperate zones, but their representatives become
+scarcer with the increasing distance from the equator. North of 40°
+lat. N. many genera have disappeared, or are met with in isolated
+examples only, as _Carcharias_, _Zygæna_, _Notidanus_, _Myliobatidæ_,
+_Dactylopterus_, _Echeneis_, _Nomeus_, _Coryphæna_, _Schedophilus_,
+_Seriola_, _Temnodon_, _Antennarius_, _Sternoptychidæ_, _Astronesthes_,
+_Exocoetus_, _Tetrodon_, _Diodon_; and only one genus of Sharks,
+_Galeocerdo_, approaches the Arctic circle. Some few species, like
+_Antennarius_, _Scopelus_, are carried by currents near to the northern
+confines of the temperate zones; but such occurrences are accidental,
+and these fishes must be regarded as entirely foreign to the fauna of
+those latitudes. On the other hand, some Pelagic fishes inhabit the
+temperate zones, whilst their occurrence within the tropics is very
+problematical; thus, in the Atlantic, _Thalassorhinus_, _Selache_,
+_Læmargus_, _Centrolophus_, _Diana_, _Ausonia_, _Lampris_ (all genera
+composed of one or two species only). Beside the Shark mentioned, no
+other Pelagic fishes are known from the Arctic Ocean.
+
+We possess very little information about the Pelagic fish-fauna of
+the Southern oceans. So much only is certain, that the tropical forms
+_gradually_ disappear; but it would be hazardous, in the present
+state of our knowledge, to state even approximately, the limits of
+the southward range of a single genus. Scarcely more is known about
+the appearance of types peculiar to the Southern temperate zone; for
+instance, the gigantic Shark (_Rhinodon_), representing the Northern
+Selache, near the coasts of South Africa, and the Scombroid genus,
+_Gastrochisma_, in the South Pacific.
+
+The largest of marine fishes, _Rhinodon_, _Selache_, _Carcharodon_,
+_Myliobatidæ_, _Thynnus_, _Xiphiidæ_, _Orthagoriscus_, belong to the
+Pelagic Fauna. Young fishes are frequently found in mid-ocean, which
+are the offspring of shore-fishes normally depositing their spawn near
+the coast. The manner, in which this fry passes into the open sea, is
+unknown; for it has not yet been ascertained whether it is carried by
+currents from the place where it was deposited originally, or whether
+shore-fishes sometimes spawn at a distance from the coast. We may
+remember that shore-fishes inhabit not only coasts but also submerged
+banks with some depth of water above, and that, by the action of the
+water, spawn deposited on these latter localities is very liable to
+be dispersed over wide areas of the ocean. Embryoes of at least some
+shore-fishes hatched under abnormal conditions seem to have an abnormal
+growth up to a certain period of their life, when they perish. The
+_Leptocephali_ must be regarded as such abnormally developed fish
+(see p. 179). Fishes of a similar condition are the so-called Pelagic
+_Plagusiæ_, young Pleuronectoids, the origin of which is still unknown.
+As mentioned before, Flat-fishes, like all the other Anacanths, are
+otherwise not represented in the Pelagic fauna.
+
+  [Illustration: Figs. 109 and 110.--_Antennarius
+  candimaculatus_, a pelagic fish, from the Indian Ocean.]
+
+
+
+
+                             CHAPTER XXI.
+
+                      THE FISHES OF THE DEEP SEA.
+
+
+The knowledge of the existence of deep-sea fishes is one of the
+recent discoveries of ichthyology. It is only about twenty years ago
+that, from the evidence afforded by the anatomical structure of a
+few singular fishes obtained in the North Atlantic, an opinion was
+expressed that these fishes inhabited great depths of the ocean, and
+that their organisation was specially adapted for living under the
+physical abyssal conditions. These fishes agreed in the character
+of their connective tissue, which was so extremely weak as to yield
+to, and to break under, the slightest pressure, so that the greatest
+difficulty is experienced to preserve their body in its continuity.
+Another singular circumstance was, that some of the specimens were
+picked up floating on the surface of the water, having met their
+deaths whilst engaged in swallowing or digesting another fish not much
+inferior or even superior in size to themselves.
+
+The first peculiarity was accounted for by the fact that, if those
+fishes really inhabited the great depths supposed, their removal from
+the enormous pressure under which they lived would be accompanied by
+such an expansion of gases within their tissues as to rupture them, and
+to cause a separation of the parts which had been held together by the
+pressure. The second circumstance was explained thus:--A raptatorial
+fish organised to live at a depth of between 500 and 800 fathoms seizes
+another usually inhabiting a depth of between 300 and 500 fathoms. In
+its struggles to escape, the fish seized, nearly as large or strong as
+the attacking fish, carries the latter out of its depth into a higher
+stratum, where the diminished pressure causes such an expansion of
+gases as to make the destroyer with its victim rise with increasing
+rapidity towards the surface, which they reach dead or in a dying
+condition. Specimens in this condition are not rarely picked up; and
+as, of course, comparatively few can by accident fall into the hands of
+naturalists, occurrences of the kind related must happen very often.
+
+Thus, the existence of fishes peculiarly adapted for the deep sea has
+been a fact maintained and admitted for some time in Ichthyology; and
+as the same genera and species were found at very distant parts of
+the ocean, it was further stated that those Deep-sea fishes were not
+limited in their range, and that, consequently, the physical conditions
+of the depths of the ocean must be the same or nearly the same over
+the whole globe. That Deep-sea fishes were not of a peculiar order,
+but chiefly modified forms of surface types, was another conclusion
+arrived at from the sporadic evidence collected during the period which
+preceded systematic deep-sea dredging.
+
+However, nothing was positively known as to the exact depths inhabited
+by those fishes until observations were made during the voyage of
+H.M.S. “Challenger.” The results obtained by this expedition afforded a
+surer and more extended basis for our knowledge of Deep-sea fishes.
+
+The physical conditions of the deep sea, which must affect the
+organisation and distribution of fishes, are the following:--
+
+1. Absence of sunlight. Probably the rays of the sun do not penetrate
+to, and certainly do not extend beyond, a depth of 200 fathoms,
+therefore we may consider this to be the depth where the Deep-sea
+fauna commences. Absence of light is, of necessity, accompanied by
+modifications of the organs of vision and by simplification of colours.
+
+2. The absence of sunlight is in some measure compensated for by the
+presence of phosphorescent light, produced by many marine animals, and
+also by numerous Deep-sea fishes.
+
+3. Depression and equality of the temperature. At a depth of 500
+fathoms the temperature of the water is already as low as 40° Fahr.,
+and perfectly independent of the temperature of the surface-water; and
+from the greatest depths upwards to about 1000 fathoms the temperature
+is uniformly but a few degrees above freezing-point. Temperature,
+therefore, ceases to offer an obstacle to the unlimited dispersal of
+Deep-sea fishes.
+
+4. The increased pressure by the water. The pressure of the atmosphere
+on the level of the sea amounts to fifteen pounds per square inch of
+the surface of the body of an animal; but the pressure amounts to a ton
+weight for every 1000 fathoms of depth.
+
+5. With the sunlight, vegetable life ceases in the depths of the sea.
+All Deep-sea fishes are therefore carnivorous; the most voracious
+feeding frequently on their own offspring, and the toothless kinds
+being nourished by the animalcules which live on the bottom, or which,
+“like a constant rain,” settle down from the upper strata towards the
+bottom of the sea.
+
+6. The perfect quiet of the water at great depths. The agitation of
+the water, caused by the disturbances of the air, does not extend
+beyond the depth of a few fathoms; below this surface-stratum there is
+no other movement except the quiet flow of ocean-currents, and near
+the bottom of the deep sea the water is probably in a state of almost
+entire quiescence.
+
+The effect upon fishes of the physical conditions described is
+clearly testified by the modification of one or more parts of their
+organisation, so that every Deep-sea fish may be recognised as such,
+without the accompanying positive evidence that it has been caught
+at a great depth; and _vice versa_, fishes reputed to have been
+obtained at a great depth, and not having any of the characteristics
+of the dwellers of the deep sea, must be regarded as surface-fishes.
+
+The most striking characteristic, found in many Deep-sea fishes,
+is in relation to the tremendous pressure under which they live.
+Their osseous and muscular systems are, as compared with the same
+parts of surface-fishes, very feebly developed. The bones have a
+fibrous, fissured, and cavernous texture; are light, with scarcely
+any calcareous matter, so that the point of a needle will readily
+penetrate them without breaking. The bones, especially the vertebræ,
+appear to be most loosely connected with one another; and it requires
+the most careful handling to prevent the breaking of the connective
+ligaments. The muscles, especially the great lateral muscles of the
+trunk and tail, are thin, the fascicles being readily separated from
+one another or torn, the connective tissue being extremely loose,
+feeble, or apparently absent. This peculiarity has been observed
+in the _Trachypteridæ_, _Plagyodus_, _Chiasmodus_, _Melanocetus_,
+_Saccopharynx_. But we cannot assume that it actually obtains whilst
+those fishes exist under their natural conditions. Some of them are
+most rapacious creatures which must be able to execute rapid and
+powerful movements to catch and overpower their prey; and for that
+object their muscular system, thin as its layers may be, must be as
+firm, and the chain of the segments of their vertebral column as firmly
+linked together as in surface-fishes. Therefore, it is evident that the
+change which the body of those fishes has undergone on their withdrawal
+from the pressure under which they live is a much aggravated form of
+the affection that is experienced by persons reaching great altitudes
+in their ascent of a mountain or in a balloon. In every living organism
+with an intestinal tract there are accumulations of free gases; and,
+moreover, the blood and other fluids, which permeate every part of the
+body, contain gases in solution. Under greatly diminished pressure
+these gases expand, so that, if the withdrawal from a depth is not
+an extremely slow and gradual process, the various tissues must be
+distended, loosened, ruptured; and what is a vigorous fish at a depth
+of 500 or more fathoms, appears at the surface as a loosely-jointed
+body which, if the skin is not of sufficient toughness, can only be
+kept together with difficulty. At great depths a fibrous osseous
+structure and a thin layer of muscles suffices to obtain the same
+results for which, at the surface, thickness of muscle and firm osseous
+or cartilaginous tissue are necessary.
+
+The muciferous system of many Deep-sea fishes is developed in an
+extraordinary degree. We find already in fishes which are comparatively
+little removed from the surface (that is to depths of 100–200 fathoms),
+the lateral line much wider than in their congeners or nearest allies
+which live on the surface, as in _Trachichthys_, _Hoplostethus_, many
+_Scorpænidæ_. But in fishes inhabiting depths of 1000 and more fathoms,
+the whole muciferous system is dilated; it is especially the surface of
+the skull which is occupied by large cavities (_Macruridæ_, deep-sea
+_Ophidiidæ_), and the whole body seems to be covered with a layer of
+mucus. These cavities collapse and shrink in specimens which have been
+preserved in spirit for some time, but a re-immersion in water for a
+short time generally suffices to show the immense quantity of mucus
+secreted by them. The physiological use of this secretion is unknown;
+it has been observed to have phosphorescent properties in perfectly
+fresh specimens.
+
+The colours of Deep-sea fishes are extremely simple, their bodies
+being either black or silvery; in a few only are some filaments or the
+fin-rays of a bright scarlet colour. Among the black forms albinoes are
+not scarce.
+
+The organ of sight is the first to be affected by a sojourn in deep
+water. Even in fishes which habitually live at a depth of only 80
+fathoms, we find the eye of a proportionally larger size than in
+their representatives at the surface. In such fishes the eyes increase
+in size with the depth inhabited by them, down to the depth of 200
+fathoms, the large eyes being necessary to collect as many rays of
+light as possible. Beyond that depth small-eyed fishes as well as
+large-eyed occur, the former having their want of vision compensated
+for by tentacular organs of touch, whilst the latter have no such
+accessory organs, and evidently see only by the aid of phosphorescence.
+In the greatest depths blind fishes occur with rudimentary eyes and
+without special organs of touch.
+
+Many fishes of the deep sea are provided with more or less numerous,
+round, shining, mother-of-pearl-coloured bodies, imbedded in the
+skin. These so-called phosphorescent or luminous organs are either
+larger bodies of an oval or irregularly elliptical shape placed on the
+head, in the vicinity of the eye, or smaller round globular bodies
+arranged symmetrically in series along the side of the body and tail,
+especially near the abdominal profile, less frequently along the back.
+The former have not yet been anatomically examined. The number of
+pairs of the latter is in direct relation to that of the segments of
+the vertebral column, the muscular system, etc. (meta*-meres); and
+two kinds may be distinguished differing from each other in their
+anatomical structure. The organs of one kind consist of an anterior,
+biconvex, lens-like body, which is transparent during life, simple
+or composed of rods (_Chauliodus_); and of a posterior chamber which
+is filled with a transparent fluid, and coated with a dark membrane
+composed of hexagonal cells, or of rods arranged as in a retina. This
+structure is found in _Astronesthes_, _Stomias_, _Chauliodus_, etc. In
+the other kind the organ shows throughout a simply glandular structure,
+but apparently without an efferent duct (_Gonostoma_, _Scopelus_,
+_Maurolicus_, _Argyropelecus_). Branches of the spinal nerves run to
+each organ, and are distributed over the retina-like membrane or the
+glandular follicles. The former kind of organs are considered by some
+naturalists true organs of vision (accessory eyes), the function of the
+latter being left unexplained by them.
+
+Although, thus, these organs morphologically differ from each other,
+there is no doubt that the functions of all have some relation to the
+peculiar conditions of light under which the fishes provided with them
+live; these fishes being either deep-sea forms or nocturnal pelagic
+kinds. There are three possible hypotheses as to the function of these
+organs:--
+
+1. All the different kinds of organs are sensory, or, in other words,
+accessory eyes.
+
+2. Only the organs with a lenticular body are sensory, and those with a
+glandular structure produce and emit phosphorescent light.
+
+3. All are producers of light.
+
+There are very serious objections to adopting the first view.
+_Scopelus_ and _Argyropelecus_ possess not only perfectly developed,
+but even large eyes, specially adapted for a nocturnal life; and
+therefore accessory organs of vision must appear to be quite
+superfluous to them. On the other hand, in Deep-sea fishes without
+external eyes, which would seem to especially require these metameric
+organs of sense, they are invariably absent. And, finally, it is
+quite inconceivable that the glandular structures should have the
+faculty of conveying impressions of light to the nervous centre.
+The second supposition seems therefore to be nearer the truth; and
+is supported by the fact that the glandular organs of Scopeli have
+actually been observed to gleam with phosphorescent light, and by the
+obvious morphological similarity of the organs with a lenticular body
+and retina-like membrane to an organ of vision. We are, moreover,
+justified, from an _à priori_ consideration, in supposing that in
+depths to which no sunlight descends, and which are illuminated by
+phosphorescent light only, peculiar organs of vision would have been
+developed. On the other hand, this supposition is opposed by the fact
+that many fishes which dwell in those abyssal depths are provided
+with large ordinary eyes (as the _Trachypteri_, the majority of
+_Macruridæ_), and, therefore, that the ordinary organ of vision is
+quite sufficient for seeing by phosphorescent light. Thus, whilst we
+must admit that those compound organs may prove to be organs of sense,
+we maintain at the same time that their morphological nature is not
+opposed to the belief that they too, like the glandular organs, are
+producers of light. It may be produced at the bottom of the posterior
+chamber, and emitted through the lenticular body in particular
+directions, with the same effect as light is sent through the convex
+glass of a “bull’s eye.” This hypothesis seems to be less bold than the
+other, which would require us to believe that vertebrate animals, with
+a nervous centre specialised for the reception of the impressions of
+the higher senses, should receive them through the spinal chord.
+
+   [See _Ussow_, “Ueber den Bau der sogenannten
+   augenaehnlichen Flecken einiger Knochenfische.” St. Petersburg,
+   Bullet. 1879.]
+
+Whenever we find in a fish long delicate filaments, developed in
+connection with the fins or the extremity of the tail, we may
+conclude that it is an inhabitant of still water and of quiet habits.
+Many deep-sea fishes (_Trachypteridæ_, _Macruridæ_, _Ophidiidæ_,
+_Bathypterois_) are provided with such filamentous prolongations, the
+development of which is perfectly in accordance with their sojourn in
+the absolutely quiet waters of abyssal depths.
+
+Some of the raptatorial Deep-sea fishes have a stomach so distensible
+and capacious that it can receive a fish of twice or thrice the bulk
+of the destroyer (_Melanocetus_, _Chiasmodus_, _Saccopharynx_).
+Deglutition is performed in them not by means of the muscles of the
+pharynx, as in other fishes, but by the independent and alternate
+action of the jaws, as in Snakes. These fishes cannot be said to
+swallow their food, but rather draw themselves over their victim, in
+the fashion of an _Actinia_.
+
+Before the voyage of H.M.S. “Challenger,” scarcely thirty Deep-sea
+fishes were known. This number is now much increased by the discovery
+of many new species and genera; but, singularly, no new types of
+families were discovered: nothing but what might have been expected
+from our previous knowledge of this group of fishes. Modifications of
+certain organs, perfectly novel, and of the greatest interest, were
+found, as we shall see in the “Systematic Part;” but the most important
+results of this voyage are that the general character of the abyssal
+fish-fauna, the abundance of fishes, and the exact depths to which
+fishes may descend, have been ascertained.
+
+However, the statements of the depths at which the fishes collected by
+the “Challenger” were taken cannot be received without some critical
+examination of each individual species. No precaution was taken to
+keep the mouth of the dredge closed during its descent or ascent, and
+therefore it is quite within the limits of probability that sometimes
+fishes were accidentally enclosed within the dredge, whilst it was
+traversing the surface strata. And this has happened more than once;
+for it is quite certain that common surface fishes like _Sternoptyx_
+and _Astronestles_, never ranged to a depth of 2500 fathoms. On the
+other hand, the majority of the fishes obtained offer sufficient
+evidence from their own organisation that they live on the bottom, and
+are unable to support themselves in the water at a certain distance
+from the bottom or surface; and, consequently, that they actually were
+obtained at the depth to which the dredge descended.
+
+As far as the observations go at present, no distinct bathymetrical
+regions, which would be characterised by peculiar forms, can be
+defined. The depths from 200 to 600 fathoms are inhabited by
+numerous forms, still strongly reminding us of surface types. To this
+fauna belong the few Chondropterygians of the deep sea, a Sebastes
+and Setarches, a Beryx and Polymixia, a Cottus, etc.; but they are
+associated with many others which descend to the greatest depths.
+And before anything like a division into bathymetrical zones can be
+attempted, the observations of the “Challenger” expedition must be
+confirmed and supplemented by other series of similar systematic
+observations. One of the most startling conclusions at which we would
+have to arrive from the “Challenger” observations is, that some of the
+species of Deep-sea fishes would range from a depth of some 300 fathoms
+down to one of 2000 fathoms; or, in other words, that a fish which
+has once attained in its organisation to that modification by which
+it is enabled to exist under the pressure of half a ton, can easily
+accommodate itself to one of two tons or more,--a conclusion which is
+not in accordance with anatomical facts, and which must be confirmed by
+other observations before we can adopt it. But if the vertical range of
+Deep-sea fishes is actually as it appears from the “Challenger” lists,
+then there is no more distinct vertical than horizontal distribution of
+Deep-sea fishes.
+
+The greatest depth reached hitherto by a dredge in which fishes were
+enclosed is 2900 fathoms. But the specimens thus obtained belong to a
+species (_Gonostoma microdon_), which seems to be extremely abundant
+in upper strata of the Atlantic and Pacific, and were therefore most
+likely caught by the dredge in its ascent. The next greatest depth,
+viz., 2750 fathoms, must be accepted as one at which fishes undoubtedly
+do live; the fish obtained from this depth of the Atlantic, _Bathyophis
+ferox_, showing by its whole habit that it is a form living on the
+bottom of the ocean.
+
+The fish-fauna of the deep sea is composed chiefly of forms or
+modifications of forms which we find represented at the surface in the
+cold and temperate zones, or which appear as nocturnal pelagic forms.
+The Chondropterygians are few in number, not descending to a depth of
+more than 600 fathoms. The Acanthopterygians, which form the majority
+of the coast and surface faunas, are also scantily represented; genera
+identical with surface types are confined to the same inconsiderable
+depths as the Chondropterygians, whilst those Acanthopterygians which
+are so much specialised for the life in the deep sea as to deserve
+generic separation, range from 200 to 2400 fathoms. Three distinct
+families of Acanthopterygians belong to the deep-sea fauna, viz.
+_Trachypteridæ_, _Lophotidæ_, and _Notacanthidæ_; they respectively
+consist of three, one, or two genera only.
+
+_Gadidæ_, _Ophidiidæ_, and _Macruridæ_ are very numerous, ranging
+through all depths; they constitute about one-fourth of the whole
+deep-sea fauna.
+
+Of _Physostomi_, the families of _Sternoptychidæ_, _Scopelidæ_,
+_Stomiatidæ_, _Salmonidæ_, _Bathythrissidæ_, _Alepocephalidæ_,
+_Halosauridæ_, and _Murænidæ_ are represented. Of these the
+_Scopeloids_ are the most numerous, constituting nearly another fourth
+of the fauna. _Salmonidæ_ are scarce, with three small genera only.
+_Bathythrissidæ_ include one species only, which is probably confined
+in its vertical as well as horizontal range; it occurs at a depth
+of about 350 fathoms in the sea of Japan. The _Alepocephalidæ_ and
+_Halosauridæ_, known before the “Challenger” expedition from isolated
+examples only, prove to be true, widely-spread, deep-sea types. Eels
+are well represented, and seem to descend to the greatest depths.
+
+_Myxine_ has been obtained from a depth of 345 fathoms.
+
+It will be useful to append a complete list of Deep-sea fishes, with
+the depths as ascertained by the dredgings of the “Challenger:”--
+
+
+                      _List of Deep-sea Fishes._
+
+                                                  Fathoms.
+
+    CHONDROPTERYGIANS--
+      Raja                                            565
+      Scyllium                                        400
+      Centroscyllium                                  245
+      Centrophorus                                345–500
+
+    ACANTHOPTERYGIANS--
+      Pomatomus                           (? down to) 200
+      Sebastes                                        275
+      Setarches                                       215
+      Beryx                                           345
+      Melamphaes                           (? beyond) 200
+      Polymixia                                       345
+      Nealotus
+      Nesiarchus
+      Aphanopus
+      Euoxymetopon
+      Lepidopus                                       345
+      Gempylus
+      Anomalops
+    ? Antigonia
+      Diretmus
+      Cottus                                          565
+      Bathydraco                                     1260
+      Oneirodes
+      Melanocetus johnsonii                          1850
+           „      bispinosus                          360
+      Himantolophus
+      Chaunax                                         215
+      Ceratias                                       2400
+      Halieutichthys
+      Dibranchus                                      360
+      Trachypteridæ
+      Lophotes
+      Notacanthus rissoanus                          1875
+           „      bonapartii                          400
+
+
+    ANACANTHINI--
+
+        Melanonus                                    1975
+        Halargyreus
+        Lotella marginata                         120–345
+        Physiculus                                    345
+        Uraleptus
+        Læmonema
+        Haloporphyrus australis                     55–70
+              „       lepidion                    345–600
+              „       rostratus                  600–1375
+        Chiasmodus niger                             1500
+        Sirembo grandis                              1875
+           „    macrops                               375
+           „    messieri                              345
+           „    ocellatus                             350
+           „    brachysoma                            350
+        Acanthonus armatus                           1075
+        Typhlonus nasus                              2440
+        Aphyonus gelatinosus                         1400
+        Rhinonus ater                                2150
+        Bathynectes laticeps                         2500
+             „      compressus                  1075–2500
+             „      gracilis                         1400
+        Pteridium
+        Macrurus (12 species)                     120–700
+        Coryphænoides norvegicus
+             „        serratus
+             „        nasutus                     345–565
+             „        villosus                        345
+             „        rudis                       500–650
+             „        æqualis                         600
+             „        crassiceps                  520–650
+             „        microlepis                      215
+             „        murrayi                        1100
+             „        serrulatus                      700
+             „        filicauda                 1800–2650
+             „        variabilis                1375–2425
+             „        affinis                        1900
+             „        carinatus                       500
+             „        longifilis                      565
+             „        altipinnis                 565–1875
+             „        asper                      500–1875
+             „        leptolepis                 350–2050
+             „        sclerorhynchus                 1090
+             „        denticulatus                275–520
+      Malacocephalus                                  350
+      Bathygadus cottoides                        520–700
+           „     multifilis                           500
+
+    STERNOPTYCHIDÆ--
+      Argyropelecus                                  1127 [?]
+      Sternoptyx                                   0–2500 [?]
+      Polyipnus                                       255
+      Gonostoma denudatum
+           „    microdon                         500–2900 [?]
+           „    elongatum                         360–800
+           „    gracile                          345–2425
+      Chauliodus                                 565–2560
+
+    SCOPELIDÆ--
+      Bathysaurus ferox                              1100
+           „      mollis                        1875–2385
+      Bathypterois longifilis                     520–630
+           „       longipes                          2650
+           „       quadrifilis                    500–770
+           „       longicauda                        2550
+      Chlorophthalmus agassizii                       215
+           „          nigripinnis                     120
+           „          gracilis                  1100–1425
+      Scopelus engraulis                              255
+           „   antarcticus                           1950
+           „   mizolepis                              800
+           „   dumerilii                              215
+           „   macrolepidotus                     520–630
+           „   crassiceps                        675–1550
+           „   macrostoma                       2350–2425
+           „   microps                               1375
+      Odontostomus hyalinus
+      Odontostomus humeralis                          500
+      Nannobrachium nigrum                            500
+      Ipnops murrayi                            1600–2150
+      Paralepis
+      Sudis
+      Plagyodus
+
+    STOMIATIDÆ--
+      Astronesthes niger                             2500 [?]
+      Stomias boa                                450–1800
+         „    barbatus
+         „    ferox
+      Echiostoma barbatum
+          „      micripnus                           2150
+          „      microdon                            2440
+      Malacosteus niger
+           „      indicus                             500
+      Bathyophis ferox                               2750
+
+    SALMONIDÆ--
+      Argentina
+      Microstoma
+      Bathylagus antarcticus                         1950
+          „      atlanticus                          2040
+
+    BATHYTHRISSIDÆ--
+      Bathythrissa dorsalis                           345
+
+    ALEPOCEPHALIDÆ--
+      Alepocephalus rostratus
+           „        niger                            1400
+      Platytroctes apus                              1500
+      Bathytroctes microlepis                        1090
+           „       rostratus                          675
+           „       macrolepis                        2150
+      Xenodermichthys                                 345
+
+    HALOSAURIDÆ--
+      Halosaurus owenii
+           „     affinis                              565
+           „     macrochir                      1090–1375
+           „     mediorostris                         700
+           „     rostratus                           2750
+
+
+    MURÆNIDÆ--
+      Nemichthys scolopacea
+          „      infans                          500–2500
+      Cyema atrum                               1500–1800
+      Saccopharynx
+      Synaphobranchus pinatus                    345–1200
+            „         bathybius                 1875–2050
+            „         brevidorsalis             1075–1375
+            „         affinis                         345
+      Nettastoma parviceps                            345
+
+    CYCLOSTOMATA--
+      Myxine australis                                345
+
+
+  [Illustration: Fig. 111.--_Chiasmodus niger_; obtained in
+  the North Atlantic at a depth of 1500 fathoms; the specimen has
+  swallowed a large Scopelus (_s_); _o_, ventral fin.]
+
+
+
+
+                   SYSTEMATIC AND DESCRIPTIVE PART.
+
+
+The Class of Fishes is divided into four sub-classes:--
+
+  I. PALÆICHTHYES.--Heart with a contractile conus arteriosus;
+intestine with a spiral valve; optic nerves non-decussating, or only
+partially decussating.
+
+ II. TELEOSTEI.--Heart with a non-contractile bulbus arteriosus;
+intestine without spiral valve; optic nerves decussating. Skeleton
+ossified, with completely separated vertebræ.
+
+III. CYCLOSTOMATA.--Heart without bulbus arteriosus; intestine
+simple. Skeleton cartilaginous and notochordal. One nasal aperture
+only. No jaws; mouth surrounded by a circular lip.
+
+ IV. LEPTOCARDII.--Heart replaced by pulsating sinuses; intestine
+simple. Skeleton membrano-cartilaginous and notochordal. No skull; no
+brain.
+
+
+                    FIRST SUB-CLASS: PALÆICHTHYES.
+
+_Heart with a contractile conus arteriosus;[30] intestine with a
+spiral valve;[31] optic nerves non-decussating, or only partially
+decussating;[32] skeleton cartilaginous or osseous._
+
+This sub-class comprises the Sharks and Rays, and the Ganoid fishes.
+Although based upon a singular concurrence of most important
+characters, its members exhibit as great a diversity of form, and as
+manifold modifications in the remainder of their organisation as the
+_Teleostei_. The _Palæichthyes_ stand to the _Teleostei_ in the same
+relation as the Marsupials to the Placentalia. Geologically, as a
+sub-class, they were the predecessors of Teleosteous fishes; and it is
+a remarkable fact that all those modifications which show an approach
+of the ichthyic type to the Batrachians are found in this sub-class. We
+divide it into two orders: _Chondropterygii_ and _Ganoidei_.
+
+
+                     FIRST ORDER: CHONDROPTERYGII.
+
+_Skeleton cartilaginous. Body with medial and paired fins, the
+hinder pair abdominal. Vertebral column generally heterocercal, the
+upper lobe of the caudal fin produced. Gills attached to the skin by
+the outer margin, with several intervening gill-openings: rarely one
+external gill-opening only. No gill-cover. No air-bladder. Two, three,
+or more series of valves in the conus arteriosus. Ova large and few
+in number,[33] impregnated and, in some species, developed within a
+uterine cavity. Embryo with deciduous external gills.[34] Males with
+intromittent organs attached to the ventral fins.[35]_
+
+This order, for which, also, the name _Elasmobranchii_ has
+been proposed (by Bonaparte), comprises the Sharks and Rays and
+Chimæras, and is divided into two suborders: _Plagiostomata_ and
+_Holocephala_.
+
+
+                    FIRST SUB-ORDER: PLAGIOSTOMATA.
+
+_From five to seven gill-openings. Skull with a suspensorium and the
+palatal apparatus detached. Teeth numerous._
+
+The Plagiostomes differ greatly among each other with regard to the
+general form of their body: in the Sharks or _Selachoidei_ the
+body is elongate, more or less cylindrical, gradually passing into the
+tail; their gill-openings are lateral. In the Rays, or _Batoidei_,
+the gill-openings are always placed on the abdominal aspect of the
+fish; the body is depressed, and the trunk, which is surrounded by the
+immensely developed pectoral fins, forms a broad flat disk, of which
+the tail appears as a thin and slender appendage. Spiracles are always
+present; the number of gill-openings is constantly five; no anal fin;
+dorsal fins, if present, situated on the tail. However, some of the
+Rays approach the Sharks in having the caudal portion less abruptly
+contracted behind the trunk.
+
+Fossil Plagiostomes are very numerous in all formations. Some of
+the earliest determinable fish remains are believed to be, or are,
+derived from Plagiostomes. Those which can be referred to any of
+the following families will be mentioned subsequently: but there
+are others, especially fin-spines, which leave us in doubt to which
+group of Plagiostomes their owners had any affinity, thus _Onchus_
+from the upper Silurian, continuing to carboniferous formations;
+_Dimeracanthus_, _Homocanthus_, from the Devonian; _Oracanthus_,
+_Gyracanthus_, _Tristychius_, _Astroptychius_, _Ptychacanthus_,
+_Sphenacanthus_, etc., from carboniferous formations; _Leptacanthus_,
+from the coal to the Oolite; _Cladacanthus_, _Cricacanthus_,
+_Gyropristis_, and _Lepracanthus_, from the coal measures;
+_Nemacanthus_, _Liacanthus_, from the Trias; _Astracanthus_,
+_Myriacanthus_, _Pristacanthus_, from the Jurassic group.
+
+
+                        A. SELACHOIDEI: SHARKS.
+
+The elongate cylindrical body, generally terminating in a more or
+less pointed snout, and passing into a powerful and flexible tail,
+blade-like at its extremity, gives to the Sharks a most extraordinary
+power of swimming, with regard to endurance as well as rapidity of
+motion. Many, especially the larger kinds, inhabit the open ocean,
+following ships for weeks, or pursuing shoals of fishes in their
+periodical migrations. Other large-sized sharks frequent such parts
+of the coast as offer them abundance of food; whilst the majority of
+the smaller kinds are shore fishes, rarely leaving the bottom, and
+sometimes congregating in immense numbers. The movements of sharks
+resemble in some measure those of snakes, their flexible body being
+bent in more than one curve when moving.
+
+Sharks are most numerous in the seas between the Tropics, and become
+scarcer beyond, a few only reaching the Arctic circle; it is not known
+how far they advance southwards towards the Antarctic region. Some
+species enter fresh waters, and ascend large rivers, like the Tigris
+or Ganges, to a considerable distance. The pelagic as well as the
+shore species have a wide geographical range. Very few descend to a
+considerable depth, probably not exceeding 500 fathoms. There are about
+140 different species known.
+
+Sharks have no scales like those of other fishes; their integuments
+are covered with calcified papillæ which, under the microscope, show a
+structure similar to that of teeth. If the papillæ are small, pointed,
+and close set, the skin is called “shagreen;” rarely they are larger,
+appearing as bucklers or spines, of various sizes.
+
+These fishes are exclusively carnivorous, and those armed with powerful
+cutting teeth are the most formidable tyrants of the ocean. They have
+been known to divide the body of a man in two at one bite, as if by
+the sweep of a sword. Some of the largest sharks, however, which
+are provided with very small teeth, are almost harmless, feeding on
+small fishes only or marine invertebrates. Others, particularly of
+the smaller kinds, commonly called “Dog-fishes,” have short or obtuse
+teeth, and feed on shells or any other animal substance. Sharks scent
+their food from a distance, being readily attracted by the smell of
+blood or decomposing bodies.
+
+In China and Japan, and many other eastern countries, the smaller kinds
+of sharks are eaten. Sharks’ fins form in India and China a very
+important article of trade, the Chinese preparing from them gelatine,
+and using the better sorts for culinary purposes. The fins are obtained
+not exclusively from Sharks but also from Rays, and assorted in two
+kinds, viz. “white and black.” The white consist exclusively of the
+dorsal fins, which are on both sides of the same uniform light colour,
+and reputed to yield more gelatine than the other fins. The pectoral,
+ventral, and anal fins pass under the denomination of black fins; the
+caudal fin is not used. One of the principal places where shark fishery
+is practised as a profession is Kurrachee. Dr. Buist, writing in 1850
+(“Proc. Zool. Soc.” 1850, p. 100), states that there are thirteen
+large boats, with crews of twelve men each, constantly employed in
+this pursuit; that the value of the fins sent to the market varies
+from 15,000 to 18,000 rupees; that one boat will sometimes capture at
+a draught as many as one hundred sharks of various sizes; and that the
+number total of sharks captured during the year amounts probably to not
+less than 40,000. Large quantities are imported from the African coast
+and the Arabian Gulf, and various ports on the coast of India. In the
+year 1845–46, 8770 cwt. of sharks’ fins were exported from Bombay to
+China.
+
+
+                      FIRST FAMILY--CARCHARIIDÆ.
+
+_Eye with a nictitating membrane. Mouth crescent-shaped, inferior.
+Anal fin present. Two dorsal fins, the first opposite to the space
+between pectoral and ventral fins, without spine in front._
+
+   CARCHARIAS.--Snout produced in the longitudinal axis of the
+   body; mouth armed with a series of large flat triangular teeth,
+   which have a smooth cutting or serrated edge. Spiracles absent.
+   A transverse pit on the back of the tail, at the root of the
+   caudal fin.
+
+This genus comprises the true Sharks, common in the tropical, but less
+so in the temperate seas. Between thirty and forty different species
+have been distinguished, of which one of the most common is the “Blue
+Shark” (_Carcharias glaucus_). Individuals of from twelve to fifteen
+feet are of very common occurrence, but some of the species attain a
+much larger size, and a length of 25 and more feet. Fishes of this
+genus or of closely allied genera (_Corax_, _Hemipristis_) are not
+uncommon in the chalk and tertiary formations.
+
+   GALEOCERDO.--Teeth large, flat, triangular, oblique, serrated
+   on both edges, with a deep notch on the outer margin. Spiracles
+   small. A pit on the tail, above and below, at the root of the
+   caudal fin. Two notches on the under caudal border, one of them
+   at the end of the spine.
+
+  [Illustration: Fig. 112.--Dentition of the Blue Shark (Carcharias
+  glaucus); the single teeth are of the natural size.]
+
+Three species, of which one (_G. arcticus_) is confined to the
+arctic and sub-arctic oceans. The others inhabit temperate and tropical
+seas, and all attain to a very large size.
+
+   GALEUS.--Snout produced in the longitudinal axis of the
+   body; teeth equal in both jaws, rather small, flat, triangular,
+   oblique, serrated and with a notch. Spiracles small. No pit at
+   the commencement of the caudal fin, which has a single notch on
+   its lower margin.
+
+These are small sharks, commonly called “Tope.” The species found on
+the British coast is spread over nearly all the temperate and tropical
+seas, and is common in California and Tasmania. It lives on the bottom,
+and is very troublesome to fishermen by constantly taking away bait or
+driving away the fishes which they desire to catch.
+
+   ZYGÆNA.--The anterior part of the head is broad, flattened, and
+   produced into a lobe on each side, the extremity of which is
+   occupied by the eye. Caudal fin with a single notch at its lower
+   margin. A pit at the root of the caudal fin. Spiracles none.
+   Nostrils situated on the front edge of the head.
+
+The “Hammerheads,” or Hammerheaded Sharks, have a dentition very
+similar to that of _Carcharias_, and although they do not attain to
+the same large size, they belong to the most formidable fishes of
+the ocean. The peculiar form of their head is quite unique among
+fishes; young examples have the lateral extension of the skull much
+less developed than adults. Five species are known, which are most
+abundant in the tropics. By far the most common is _Zygæna malleus_,
+which occurs in nearly all tropical and sub-tropical seas. Specimens
+of this species may be often seen ascending from the clear blue depths
+of the ocean like a great cloud. Cantor found in a female, nearly 11
+feet long, thirty-seven embryons.--Hammerheads have lived from the
+cretaceous epoch.
+
+   MUSTELUS.--The second dorsal fin is not much smaller than the
+   first. No pit at the root of the caudal, which is without
+   distinct lower lobe. Snout produced in the longitudinal axis
+   of the body. Spiracles small, behind the eyes. Teeth small,
+   numerous, similar in both jaws, obtuse, or with very indistinct
+   cusps, arranged like pavement.
+
+The “Hounds” are small Sharks, abundant on the coasts of all the
+temperate and tropical seas; two of the five species known occur on the
+coasts of Europe, viz. _M. lævis_ and _M. vulgaris_. Closely allied as
+these two species are, they yet show a most singular difference, viz.
+that a placenta is developed in the uterus for the attachment of the
+embryo in _M. lævis_ (the Γαλεὁς λεȋος of Aristotle, to whom this fact
+was already known); whilst the embryons of _M. vulgaris_ are developed
+without such placenta (see _J. Müller_, “Abhandl. Ak. Wiss.” Berl.
+1840). The Hounds are bottom fish, which feed principally on shells,
+crustaceans, and decomposing animal substances.
+
+       *       *       *       *       *
+
+Several other genera belong to the family Carchariidæ, but it will
+be sufficient to mention their names:--_Hemigaleus_, _Loxodon_,
+_Thalassorhinus_, _Triænodon_, _Leptocarcharias_, and _Triacis_.
+
+
+                        SECOND FAMILY--LAMNIDÆ.
+
+_Eye without nictitating membrane. Anal fin present. Two dorsal fins;
+the first opposite to the space between pectoral and ventral fins,
+without spine in front. Nostrils not confluent with the mouth which is
+inferior. Spiracles absent or minute._
+
+All the fishes of this family attain to a very large size, and
+are pelagic. But little is known of their reproduction. The first
+appearance of this family is indicated by _Carcharopsis_, a genus from
+carboniferous formations, the teeth of which differ from those of
+_Carcharodon_ only by having a broad fold at the base. In the chalk and
+tertiary formations almost all the existing genera are represented;
+and, besides, _Oxytes_, _Sphenodus_, _Gomphodus_, and _Ancistrodon_,
+which are known from teeth only, have been considered generically
+distinct from the living Porbeagles.
+
+   LAMNA (OXYRHINA).--The second dorsal and anal are very small.
+   A pit at the root of the caudal, which has the lower lobe much
+   developed. Side of the tail with a prominent longitudinal keel.
+   Mouth wide. Teeth large, lanceolate, not serrated, sometimes
+   with additional basal cusps. On each side of the upper jaw, at
+   some distance from the symphysis, there is one or two teeth
+   conspicuously smaller than the others. Gill-openings very wide.
+   Spiracles minute.
+
+  [Illustration: Fig. 113.--Upper and lower tooth of Lamna.]
+
+Of the “Porbeagles,” three species have been described, of which
+the one occurring in the North Atlantic, and frequently straying to
+the British coasts (_L. cornubica_), is best known. It attains to a
+length of ten feet, and feeds chiefly on fishes; its lanceolate teeth
+are not adapted for cutting, but rather for seizing and holding its
+prey, which it appears to swallow whole. According to Pennant it is
+viviparous; only two embryoes were found in the female which came under
+his observation. Haast has found this species also off the coast of New
+Zealand.
+
+   CARCHARODON.--The second dorsal and anal are very small. Pit at
+   the root of the caudal, which has the lower lobe well developed.
+   Side of the tail with a prominent longitudinal keel. Mouth wide.
+   Teeth large, flat, erect, regularly triangular, serrated. On
+   each side of the upper jaw, at some distance from the symphysis,
+   there is one or two teeth conspicuously smaller than the others.
+   Gill-openings wide.
+
+One species only is known (_C. rondeletii_), which is the most
+formidable of all Sharks. It is strictly pelagic; and appears to occur
+in all tropical and sub-tropical seas. It is known to attain to a
+length of 40 feet. The tooth figured here, of the natural size, is
+taken from a jaw 20 inches wide in its transverse diameter (inside
+measure), each half of the mandible measuring 22 inches.[36] The whole
+length of the fish was 36½ feet.
+
+Carcharodon teeth are of very common occurrence in various tertiary
+strata, and have been referred to several species, affording ample
+evidence that this type was much more numerously represented in that
+geological epoch than in the recent fauna. Some individuals attained to
+an immense size, as we may judge from teeth found in the Crag, which
+are 4 inches wide at the base, and 5 inches long, measured along their
+lateral margin. The naturalists of the “Challenger” expedition have
+made the highly interesting discovery that teeth of similar size are
+of common occurrence in the ooze of the Pacific, between Polynesia and
+the west coast of America. As we have no record of living individuals
+of that bulk having been observed, the gigantic species to which these
+teeth belonged must have become extinct within a comparatively recent
+period. Nothing is known of the anatomy, habits, and reproduction of
+the surviving species, and no opportunity should be lost of obtaining
+information on this Shark.
+
+  [Illustration: Fig. 114.--Tooth of Carcharodon rondeletii.]
+
+   ODONTASPIS.--The second dorsal and anal are not much smaller
+   than the first dorsal. No pit at the root of the caudal. Side of
+   the tail without keel. Mouth wide. Teeth large, awl-shaped, with
+   one or two small cusps at the base. Gill-openings of moderate
+   width.
+
+Large Sharks from tropical and temperate seas; two species.
+
+   ALOPECIAS.--The second dorsal and anal very small. Caudal fin
+   of extraordinary length, with a pit at its root. No keel on the
+   side of the tail. Mouth and gill-openings of moderate width.
+   Teeth equal in both jaws, of moderate size, flat, triangular,
+   not serrated.
+
+This genus consists of one species only, which is known by the name of
+“Fox-shark” or “Thresher.” It is the most common of the larger kinds
+of Sharks which occur on the British coasts; and seems to be equally
+common in other parts of the Atlantic and Mediterranean, as well as on
+the coasts of California and New Zealand. It attains to a length of
+fifteen feet, of which the tail takes more than one half; and is quite
+harmless to man. It follows the shoals of Herrings, Pilchards, and
+Sprats in their migrations, destroying incredible numbers. When feeding
+it uses the long tail in splashing the surface of the water, whilst it
+swims in gradually decreasing circles round a shoal of fishes, which
+are thus kept crowded together, falling an easy prey to their enemy.
+Statements that it has been seen to attack Whales and other large
+Cetaceans, rest upon erroneous observations.
+
+   SELACHE.--The second dorsal and anal very small. A pit at the
+   root of the caudal fin, which is provided with a lower lobe.
+   Side of the tail with a keel. Gill-openings extremely wide.
+   Teeth very small, numerous, conical, without serrature or
+   lateral cusps.
+
+Also this genus consists of one species only, the “Basking Shark”
+(Pélerin of the French). It is the largest Shark of the North Atlantic,
+growing to a length of more than thirty feet. It is quite harmless if
+not attacked; its food consisting of small fishes, and other small
+marine animals swimming in shoals. On the west coast of Ireland it
+is chased for the sake of the oil which is extracted from the liver,
+one fish yielding from a ton to a ton and a-half. Its capture is not
+unattended with danger, as one blow from the enormously strong tail is
+sufficient to stave in the sides of a large boat. At certain seasons
+it is gregarious, and many specimens may be seen in calm weather lying
+together motionless, with the upper part of the back raised above the
+surface of the water; a habit from which this Shark has derived its
+name. The buccal and branchial cavities are of extraordinary width,
+and, in consequence of the flabby condition of those parts, the head
+presents a variable and singular appearance in specimens lying dead on
+the ground. This peculiarity, as well as the circumstance that young
+specimens have a much longer and more pointed snout than adult ones,
+has led to the erroneous opinion that several different genera and
+species of Basking Shark occur in the European seas. The branchial
+arches of _Selache_ are provided with a very broad fringe of
+long (five to six inches) and thin gill-rakers, possessing the same
+microscopical structure as the teeth and dermal productions of Sharks.
+Similar gill-rakers have been found in a fossil state in the Crag of
+Anvers in Belgium, proving the existence of this Selachian type in the
+tertiary epoch. Nothing is known of the reproduction of this fish.
+The latest contributions to its history are by _Steenstrup_ in
+“Overs. Dansk. Vidensk. Selsk., Forhandl.” 1873, and by _Pavesi_
+in “Annal. Mus. Civ. Geneva,” 1874 and 1878.
+
+
+                      THIRD FAMILY--RHINODONTIDÆ.
+
+_No nictitating membrane. Anal fin present. Two dorsal fins, the
+first nearly opposite to the ventrals, without spine in front. Mouth
+and nostril near the extremity of the snout._
+
+This small family comprises one species only, _Rhinodon typicus_,
+a gigantic Shark, which is known to exceed a length of fifty feet,
+but is stated to attain that of seventy. It does not appear to be
+rare in the western parts of the Indian Ocean, and possibly occurs
+also in the Pacific. It is one of the most interesting forms, not
+unlike the Basking Shark of the Northern Seas, having gill-rakers like
+that species; but very little is known of its structure and mode of
+life. It is perfectly harmless, its teeth being extremely small and
+numerous, placed in broad bands; it has been stated to feed on tang,
+an observation which requires confirmation. The snout is very broad,
+short, and flat; the eyes are very small. A pit at the root of the
+caudal fin which has the lower lobe well developed; side of the tail
+with a keel. A characteristic figure of this fish has been given by A.
+Smith in his “Illustrations of the Zoology of South Africa,” Plate 26,
+from a specimen which came ashore at the Cape of Good Hope.
+
+  [Illustration: Fig. 115.--Dentition of Notidanus indicus. _a_,
+  teeth in function; _b_, teeth in reserve; _u_, upper, and _l_,
+  lower, tooth, of natural size.]
+
+
+                      FOURTH FAMILY--NOTIDANIDÆ.
+
+_No nictitating membrane. One dorsal fin only, without spine,
+opposite to the anal._
+
+   NOTIDANUS.--Dentition unequal in the jaws: in the upper jaw
+   one or two pairs of awl-shaped teeth, the following six being
+   broader, and provided with several cusps, one of which is much
+   the strongest. Lower jaw with six large comb-like teeth on each
+   side, beside the smaller posterior teeth. Spiracles small, on
+   the side of the neck. No pit at the root of the caudal fin.
+   Gill-openings wide, six in number in _Hexanchus_, seven in
+   _Heptanchus_.
+
+Four species are known, distributed over nearly all the tropical and
+sub-tropical seas; they attain to a length of about fifteen feet.
+Fossil teeth belonging to this type have been found in Jurassic and
+later formations (_Notidanus_ and _Aellopos_).
+
+
+                       FIFTH FAMILY--SCYLLIIDÆ.
+
+_Two dorsal fins, without spine: the first above or behind the
+ventrals; anal fin present. No nictitating membrane. Spiracle always
+distinct. Mouth inferior. Teeth small, several series generally being
+in function._
+
+   SCYLLIUM.--The origin of the anal fin is always in advance of
+   that of the second dorsal. Nasal cavity separate from the mouth.
+   Teeth small, with a middle longer cusp, and generally one or two
+   small lateral cusps arranged in numerous series. Eggs similar to
+   those of the Rays (Fig. 79, p. 167).
+
+The fishes of this genus are of small size, and commonly called
+“Dog-fishes.” They are coast fishes, living on the bottom, and feeding
+on Crustaceans, dead fishes, etc. None of the eight species known have
+a very wide distribution, but where they occur they are generally
+sufficiently abundant to prove troublesome to fishermen. They inhabit
+most parts of the temperate and tropical seas. On the British coasts
+two species are found, the “Larger” and “Lesser spotted Dog-fish,”
+_Scyllium canicula_ and _Scyllium catulus_, which are said to be more
+plentiful among the Orkney Islands than elsewhere. They are scarcely
+ever brought to market; but the fishermen of some localities do not
+disdain to eat them. Their flesh is remarkably white, a little
+fibrous, and dry. In the Orkneys they are skinned, split up, cleaned,
+and then spread out on the rocks to dry for home consumption. The skins
+are used for smoothing down cabinet-work. It would be worth while to
+apply the fins of these and other Sharks, which are so extensively
+used in China for making gelatine soups, to the same purpose in this
+country, or to dry them for exportation to the East. Most of the
+species of Dog-fishes are spotted, and those of the allied genera,
+_Parascyllium_ and _Chiloscyllium_, very handsomely ornamented.
+
+Closely allied to _Scyllium_ is _Pristiurus_, from the coasts of
+Europe, which is provided with a series of small flat spines on each
+side of the upper edge of the caudal fin.
+
+Fossil forms of Dog-fishes are not scarce in the Lias and Chalk:
+_Scylliodus_, _Palæoscyllium_, _Thyellina_, _Pristiurus_.
+
+   GINGLYMOSTOMA.--The second dorsal fin opposite to, and somewhat
+   in advance of, the anal. Eyes very small; spiracle minute and
+   behind the eye. Nasal and buccal cavities confluent. The nasal
+   valves of both sides form one quadrangular flap in front of the
+   mouth, each being provided with a free cylindrical cirrhus. The
+   fourth and fifth gill-openings are close together. The teeth
+   stand either in many series, each having a strong median cusp
+   and one or two smaller ones on each side (_Ginglymostoma_), or
+   they stand in a few (three) series only, the foremost only being
+   in function, and each tooth having a convex, finely and equally
+   serrated margin (_Nebrius_).
+
+Four species from the tropical parts of the Atlantic and Indian Oceans,
+attaining to a length of some 12 feet. Pelagic.
+
+   STEGOSTOMA.--The first dorsal above the ventrals, the second in
+   advance of the anal, which is very close to the caudal. Tail,
+   with the caudal fin, exceedingly long, measuring one-half of the
+   total length. Eyes very small, spiracle as wide as, and situated
+   behind, the orbit. Nasal and buccal cavities confluent. Snout
+   very obtuse; upper lip very thick, like a pad, bent downwards
+   over the mouth, with a free cylindrical cirrhus on each side.
+   Teeth small, trilobed, in many series, occupying in both jaws
+   a transverse flat subquadrangular patch. The fourth and fifth
+   gill-openings are close together.
+
+The single species (_St. tigrinum_) for which this genus has been
+formed, is one of the commonest and handsomest sharks of the Indian
+Ocean. Young individuals keep generally close to the coasts, whilst
+the adult, which are from 10 to 15 feet long, are not rarely met in
+the open ocean. The colour is a brownish yellow, ornamented with black
+or brown transverse bands, or with snuff-coloured rounded spots; hence
+this shark is frequently mentioned by the names of “Zebra-Shark” or
+“Tiger-Shark.”
+
+  [Illustration: Fig. 116.--Chiloscyllium trispeculare, from
+  North-western Australia.]
+
+   CHILOSCYLLIUM.--The first dorsal fin above or behind the
+   ventrals. Anal fin placed far behind the second dorsal, and very
+   close to the caudal. Spiracle very distinct, below the eye.
+   Nasal and buccal cavities confluent. Nasal valve folded, with a
+   cirrhus. Teeth small, triangular, with or without lateral cusps.
+   The two last gill-openings close together.
+
+“Dog-fishes,” from the Indian Ocean, of small size. Four species are
+known, of which one, _Ch. indicum_, is one of the commonest
+shore-fishes on the coasts of this region, extending from the southern
+extremity of the African Continent to Japan.
+
+  [Illustration: Fig. 117.--Confluent nasal and buccal cavities of
+  the same fish.]
+
+   CROSSORHINUS.--The first dorsal behind the ventrals, the second
+   in advance of the anal, which is very close to the caudal. Tail
+   rather short. Eyes small. Spiracle a wide oblique slit, behind
+   and below the eye. Nasal and buccal cavities confluent. Head
+   broad, flat, with the snout very obtuse; mouth wide, nearly
+   anterior. A free nasal cirrhus; sides of the head with skinny
+   appendages. Anterior teeth rather large, long and slender,
+   without lateral lobes, the lateral tricuspid, smaller, forming
+   a few series only. The fourth and fifth gill-openings close
+   together.
+
+Three species are known from the Australian and Japanese coasts. They
+are evidently ground-sharks, which lie concealed on the bottom watching
+for their prey. In accordance with this habit their colour closely
+assimilates that of a rock or stone covered with short vegetable and
+coralline growth--a resemblance increased by the frond-like tentacles
+on the side of the head. This peculiarity of the integuments, which is
+developed in a yet higher degree in Pediculati and Lophobranchs, is not
+met with in any other Selachian. These Sharks grow to a length of 10
+feet.
+
+
+                      SIXTH FAMILY--HYBODONTIDÆ.
+
+_Two dorsal fins, each with a serrated spine. Teeth rounded,
+longitudinally striated, with one larger, and from two to four smaller
+lateral cusps. Skin covered with shagreen._
+
+Extinct. From carboniferous, liassic, and triassic formations. Several
+genera have been distinguished; and if _Cladodus_ belongs to this
+family, it would have been represented even in the Devonian.
+
+  [Illustration: Fig. 118.--Spine of Hybodus subcarinatus.]
+
+
+                    SEVENTH FAMILY--CESTRACIONTIDÆ.
+
+_No nictitating membrane. Two dorsal fins, the first opposite to
+the space between pectoral and ventral fins; anal fin present. Nasal
+and buccal cavities confluent. Teeth obtuse, several series being in
+function._
+
+  [Illustration: Fig. 119.--Jaws of Port Jackson Shark, Cestracion
+  philippi.]
+
+  [Illustration: Fig. 120.--Upper jaw of the same, half natural
+  size.]
+
+This family is one of particular interest, because representatives of
+it occur in numerous modifications in primary and secondary strata.
+Their dentition is uniformly adapted for the prehension and mastication
+of crustaceous and hard-shelled animals. The fossil forms far exceeded
+in size the species of the only surviving genus; they make, their
+appearance with _Ctenoptychius_ in the Devonian; this is succeeded
+in the coal-measures by _Psammodus_, _Chomatodus_, _Petrodus_,
+_Coch__liodus_, _Polyrhizodus_, etc.; in the Trias and Chalk by
+_Strophodus_, _Acrodus_, _Thectodus_, and _Ptychodus_. Of the 25 genera
+known, 22 have lived in the periods preceding the Oolitic.
+
+   CESTRACION (HETERODONTUS).--Each dorsal fin armed with a spine
+   in front; the second in advance of the anal. Mouth rather
+   narrow. Spiracles small, below the posterior part of the eye.
+   Gill-openings rather narrow. Dentition similar in both jaws,
+   viz. small obtuse teeth in front, which in young individuals are
+   pointed and provided with from three to five cusps. The lateral
+   teeth are large, padlike, twice as broad as long, arranged in
+   oblique series, one series being formed by much larger teeth
+   than those in the other series.
+
+  [Illustration: Fig. 121.--Cochliodus contortus.]
+
+  [Illustration: Fig. 122.--Cestracion galeatus, Australia.]
+
+Four species are known from Japan, Amboyna, Australia, the Galapagoes
+Islands, and California; none exceed a length of 5 feet. The egg has
+been figured on p. 168 (Fig. 80).
+
+
+                       EIGHTH FAMILY--SPINACIDÆ.
+
+_No membrana nictitans. Two dorsal fins; no anal. Mouth but slightly
+arched; a long, deep, straight, oblique groove on each side of the
+mouth. Spiracles present; gill-openings narrow. Pectoral fins not
+notched at their origin._
+
+The oldest representative of this family (_Palæospinax_) occurs at
+Lyme Regis; its skin is granular; each dorsal fin possesses a spine;
+the teeth in the jaws are dissimilar--the upper being multicuspid,
+longitudinally ribbed as in Hybodus, the lower smooth and tricuspid.
+_Drepanophorus_ and _Spinax primævus_ occur in Cretaceous formations of
+England and the Lebanon.
+
+   CENTRINA.--Each dorsal fin with a strong spine. Trunk rather
+   elevated, trihedral, with a fold of the skin running along each
+   side of the belly. Teeth of the lower jaw erect, triangular,
+   finely serrated; those of the upper slender, conical, forming a
+   group in front of the jaw. Spiracles wide, behind the eye.
+
+One species, _Centrina salviani_, from the Mediterranean and
+neighbouring parts of the Atlantic; of small size.
+
+   ACANTHIAS.--Each dorsal fin with a spine. Teeth equal in both
+   jaws, rather small; their point is so much turned aside that
+   the inner margin of the tooth forms the cutting edge. Spiracles
+   rather wide, immediately behind the eye.
+
+The two species of “Spiny Dog-fishes,” _A. vulgaris_ and _A.
+blainvillii_, have a very remarkable distribution, being found in the
+temperate seas of the Northern and Southern Hemispheres, but not in the
+intermediate tropical zone. They are of small size, but occur at times
+in incredible numbers, 20,000 having been taken in one scene on the
+Cornish coast. They do much injury to the fishermen by cutting their
+lines and carrying off their hooks.
+
+   CENTROPHORUS.--Each dorsal fin with a spine which, however, is
+   sometimes so small as to be hidden below the skin. Mouth wide.
+   Teeth of the lower jaw with the point more or less inclined
+   backwards and outwards. Upper teeth erect, triangular, or
+   narrow, lanceolate, with a single cusp. Spiracles wide, behind
+   the eye.
+
+Eight species are known from the southern parts of the European seas,
+and one from the Moluccas; they do not appear to exceed a length
+of five feet. According to the observations of E. P. Wright, some
+of the species at least live at a considerable depth, perhaps at a
+greater depth than any of the other known Sharks. The Portuguese
+fishermen fish for them in 400 or 500 fathoms with a line of some 600
+fathoms in length. The Sharks caught were specimens of _Centrophorus
+coelolepis_, from three to four feet long. “These sharks, as they
+were hauled into the boat, fell down into it like so many dead pigs;
+there was not the smallest motion of their bodies. There can be no
+reasonable doubt that they were inhabitants of the same great depth as
+_Hyalonema_” and that, in fact, they were killed by being dragged
+to the surface from the pressure of water under which they lived.
+The dermal productions of some of the species have a very peculiar
+form, being leaf-shaped, pedunculate, or ribbed, or provided with an
+impression.
+
+   SPINAX.--Each dorsal fin with a spine. Teeth of the lower jaw
+   with the point so much turned aside that the inner margin of
+   the tooth forms the cutting edge. Upper teeth erect, each with
+   a long-pointed cusp and one or two small ones on each side.
+   Spiracles wide, superior, behind the eye.
+
+Three small species from the Atlantic and the southern extremity of
+America. _Centroscyllium_ is an allied genus from the coast of
+Greenland.
+
+   SCYMNUS.--Two short dorsal fins without spine, the first at a
+   considerable distance from the ventrals. Dermal productions
+   uniformly small. Nostrils at the extremity of the snout. Upper
+   teeth small, pointed; lower much larger, dilated, erect,
+   triangular, not very numerous. Spiracles wide.
+
+A single species, _S. lichia_, is rather common in the Mediterranean
+and the neighbouring parts of the Atlantic.
+
+   LÆMARGUS.--All the fins small; two dorsal fins, without spine,
+   the first at a considerable distance from the ventrals. Skin
+   uniformly covered with minute tubercles. Nostrils near the
+   extremity of the snout. The upper teeth small, narrow, conical;
+   the lower teeth numerous, in several series, the point so much
+   turned aside that the inner margin forms a cutting, non-serrated
+   edge. Jaws feeble. Spiracles of moderate width.
+
+  [Illustration: Fig. 123.--Dentition of the Greenland Shark. Some
+  teeth are represented of the natural size; those of the lower jaw
+  in three series.]
+
+The “Greenland Shark” is an inhabitant of the Arctic regions, but
+rarely straying to the latitudes of great Britain; it grows to a length
+of about 15 feet, and, although it never or but rarely attacks man, is
+one of the greatest enemies of the whale, which is often found with
+large pieces bitten out of the tail by this Shark. Its voracity is so
+great that, according to Scoresby, it is absolutely fearless of the
+presence of man whilst engaged in feeding on the carcass of a whale,
+so that it can be pierced through with a spear or knife without being
+driven away. It is stated to be viviparous, and to produce about four
+young at a birth.
+
+  [Illustration: Fig. 124.--Læmargus borealis, Greenland Shark.]
+
+   ECHINORHINUS.--Two very small dorsal fins, without spine, the
+   first opposite to the ventrals. Skin with scattered large round
+   tubercles. Nostrils midway between the mouth and the end of the
+   snout. Teeth equal in both jaws, very oblique, the point being
+   turned outwards; several strong denticulations on each side of
+   the principal point. Spiracles small.
+
+The “Spinous Shark” is readily recognised by the short bulky form of
+its body, short tail, and large spinous tubercles. It is evidently a
+ground-shark, which probably lives at some depth and but accidentally
+comes to the surface. More frequently met with in the Mediterranean, it
+has been found several times on the south coast of England, and near
+the Cape of Good Hope.
+
+_Euprotomicrus_ and _Isistius_ are two other genera of this family;
+they are pelagic and but little known.
+
+
+                        NINTH FAMILY--RHINIDÆ.
+
+_No anal fin; two dorsal fins. Spiracles present. Pectoral fins large,
+with the basal portion prolonged forwards, but not grown to the head._
+
+   RHINA.--Head and body depressed, flat; mouth anterior.
+   Gill-openings rather wide, lateral, partly covered by the base
+   of the pectoral. Spiracles wide, behind the eyes. Teeth conical,
+   pointed, distant. Dorsal fins on the tail.
+
+The “Angel-fish,” or “Monk-fish” (_Rh. squatina_), approaches the
+Rays as regards general form and habits. Within the temperate and
+tropical zones it is almost cosmopolitan, being well known on the
+coasts of Europe, eastern North America, California, Japan, South
+Australia, etc.; it does not seem to exceed a length of five feet; it
+is viviparous, producing about twenty young at a birth.
+
+Extinct forms, closely allied to the “Angel-fish,” are found in the
+Oolite, and have been described as _Thaumas_. The carboniferous genus,
+_Orthacanthus_, may have been allied to this family, but it was armed
+with a spine immediately behind the head.
+
+
+                     TENTH FAMILY--PRISTIOPHORIDÆ.
+
+_The rostral cartilage is produced, into an exceedingly long, flat
+lamina, armed along each edge with a series of teeth_ (saw).
+
+These Sharks resemble so much the common Saw-fishes as to be easily
+confounded with them, but their gill-openings are lateral, and not
+inferior. They are also much smaller in size, and a pair of long
+tentacles are inserted at the lower side of the saw. The four species
+known (_Pristiophorus_) occur in the Australian and Japanese seas.
+
+_Squaloraja_, from the Lias, is supposed to have its nearest
+affinities to this family.
+
+
+                          B. BATOIDEI--RAYS.
+
+In the typical Rays the body is excessively depressed, and forms, with
+the expanded pectoral fins, a circular or sub-rhomboidal disk, of which
+the slender tail appears as a more or less long appendage. In the two
+families which we shall place first (_Pristidæ_ and _Rhinobatidæ_),
+the general habit of the body still resembles that of the Sharks,
+but the gill-openings are ventral, as in the true Rays; the anal fin
+is invariably absent, and the dorsal fins, if developed, are placed
+on the tail. The mode of life of those fishes is quite in accordance
+with the form of their body. Whilst the species with a shark-like body
+and muscular tail swim freely through the water, and are capable of
+executing rapid and sustained motions, the true Rays lead a sedentary
+life, moving slowly on the bottom, rarely ascending to the surface.
+Their tail has almost entirely lost the function of an organ of
+locomotion, acting in some merely as a rudder. They progress solely by
+means of the pectoral fins, the broad and thin margins of which are set
+in an undulating motion, entirely identical with that of the dorsal and
+anal fins of the _Pleuronectidæ_. They are exclusively carnivorous,
+like the Sharks, but unable to pursue and catch rapidly-moving
+animals; therefore they feed chiefly on molluscous and crustaceous
+animals. However, the colour of their integuments assimilates so
+closely that of their surroundings, that other fishes approach them
+near enough to be captured by them. The mouth of Rays being entirely
+at the lower surface of the head, the prey is not directly seized with
+the jaws; but the fish darts over its victim so as to cover and hold it
+down with its body, when it is conveyed by some rapid motions to the
+mouth.
+
+Rays do not descend to the same depth as Sharks; with one
+exception,[37] at least, none have been known to have been caught by a
+dredge worked in more than 100 fathoms. The majority are coast fishes,
+and have a comparatively limited geographical range, none extending
+from the northern temperate zone into the southern. However, some,
+if not all the species of the family _Myliobatidæ_, which includes
+the giants of this division of Plagiostomes, have a claim of being
+included among the Pelagic fishes, as they are frequently met with
+in the open ocean at a great distance from the shore. It is probable
+that the occurrence of such individuals in the open sea indicates the
+neighbourhood of some bank or other comparatively shallow locality.
+Many species are exclusively confined to fresh water, and occur far
+inland, especially in tropical America.
+
+The majority are oviparous. All have five pairs of gill-openings. The
+number of known species is about the same as that of Sharks, viz. 140.
+
+
+                        FIRST FAMILY--PRISTIDÆ.
+
+_The snout is produced into an exceedingly long flat lamina, armed
+with a series of strong teeth along each edge_ (saw).
+
+   PRISTIS.--Body depressed and elongate, gradually passing into
+   the strong and muscular tail. Pectoral fins, with the front
+   margins quite free, not extending to the head. No tentacles
+   below the saw. Teeth in the jaws minute, obtuse. Dorsal fins
+   without spine, the first opposite or close to the base of the
+   ventrals.
+
+“Saw-fishes.” Abundant in tropical, less so in sub-tropical seas. They
+attain to a considerable size, specimens with a saw 6 feet long and 1
+foot broad at the base not being of uncommon occurrence. The saw, which
+is their weapon of attack, renders them most dangerous to almost all
+the other large inhabitants of the ocean. Its endoskeleton consists
+of three, sometimes five, rarely four, hollow cylindrical tubes,
+placed side by side, tapering towards the end, and incrusted with an
+osseous deposit. These tubes are the rostral processes of the cranial
+cartilage, and exist in all Rays, though in them they are shorter and
+much less developed. The teeth of the saw are implanted in deep sockets
+of the hardened integument. The teeth proper, with which the jaws
+are armed, are much too small for inflicting wounds or seizing other
+animals. Saw-fishes use this weapon in tearing pieces of flesh off
+an animal’s body or ripping open its abdomen. The detached fragments
+or protruding soft parts are then seized by them and swallowed. Five
+distinct species of Saw-fishes are known.
+
+Saws of extinct species have been found in the London clay of Sheppey
+and in the Bagshot sands.
+
+
+                      SECOND FAMILY--RHINOBATIDÆ.
+
+_Tail strong and long, with two well-developed dorsal fins, and a
+longitudinal fold on each side; caudal developed. Disk not excessively
+dilated, the rayed portion of the pectoral fins not being continued to
+the snout._
+
+   RHYNCHOBATUS.--Dorsal fins without spine, the first opposite to
+   the ventrals. Caudal fin with the lower lobe well developed.
+   Teeth obtuse, granular, the dental surfaces of the jaws being
+   undulated.
+
+  [Illustration: Fig. 125.--Dentition of _Rhynchobatus_.]
+
+Two species, _Rh. ancylostomus_ and _Rh. djeddensis_, are very common
+on the tropical coasts of the Indian Ocean. They feed on hard-shelled
+animals, and attain scarcely a length of 8 feet.
+
+   RHINOBATUS.--Cranial cartilage produced into a long rostral
+   process, the space between the process and pectoral fin
+   being filled by a membrane. Teeth obtuse, with an indistinct
+   transverse ridge. Dorsal fins without spine, both at a great
+   distance behind the ventral fins. Caudal fin without lower lobe.
+
+Numerous on the coasts of tropical and sub-tropical seas; about twelve
+species. _Trygonorhina_ is an allied genus from South Australia.
+
+The oolitic genus _Spathobatis_ is scarcely distinct from
+_Rhinobatus_; and another fossil from Mount Lebanon has been
+actually referred to this latter genus. _Trigorhina_ from Monte
+Postale must be placed here.
+
+
+                      THIRD FAMILY--TORPEDINIDÆ.
+
+_The trunk is a broad, smooth disk. Tail with a longitudinal fold
+on each side; a rayed dorsal fin is generally, and a caudal always,
+present. Anterior nasal valves confluent into a quadrangular lobe.
+An electric organ composed of vertical hexagonal prisms between the
+pectoral fins and the head._
+
+“Electric Rays.” The electric organs with which these fishes are armed
+are large, flat, uniform bodies, lying one on each side of the head,
+bounded behind by the scapular arch, and laterally by the anterior
+crescentic tips of the pectoral fins. They consist of an assemblage
+of vertical hexagonal prisms, whose ends are in contact with the
+integuments above and below; and each prism is subdivided by delicate
+transverse septa, forming cells, filled with a clear, trembling,
+jelly-like fluid, and lined within by an epithelium of nucleated
+corpuscles. Between this epithelium and the transverse septa and walls
+of the prism there is a layer of tissue on which the terminations
+of the nerves and vessels ramify. Hunter counted 470 prisms in each
+battery of _Torpedo marmorata_, and demonstrated the enormous
+supply of nervous matter which they receive. Each organ receives one
+branch of the Trigeminal nerve and four branches of the Vagus, the
+former, and the three anterior branches of the latter, being each as
+thick as the spinal chord (electric lobes). The fish gives the electric
+shock voluntarily, when it is excited to do so in self-defence or
+intends to stun or to kill its prey; but to receive the shock the
+object must complete the galvanic circuit by communicating with the
+fish at two distinct points, either directly or through the medium
+of some conducting body. If an insulated frog’s leg touches the fish
+by the end of the nerve only, no muscular contractions ensue on the
+discharge of the battery, but a second point of contact immediately
+produces them. It is said that a painful sensation may be produced
+by a discharge conveyed through the medium of a stream of water. The
+electric currents created in these fishes exercise all the other known
+powers of electricity: they render the needle magnetic, decompose
+chemical compounds, and emit the spark. The dorsal surface of the
+electric organ is positive, the ventral surface negative.
+
+   [The literature on the electric organ of Torpedo is very
+   extensive. Here may be mentioned _Lorenzini_, “Osservazioni
+   intorno alle Torpedini,” (1678); _Walsh_, “On the Electric
+   Property of the Torpedo,” in Philos. Trans., 1773; _Hunter_,
+   “Anatomical Observations on the Torpedo,” _ibid._;
+   _Davy_, “Observations on the Torpedo,” in Philos. Trans.,
+   1834; _Matteucci_ and _Savi_, “Traité des Phénomènes
+   Electro-Physiologiques,” 1844.]
+
+Of the genus _Torpedo_ six species are known, distributed over the
+Atlantic and Indian Oceans; three of them are rather common in the
+Mediterranean, and one (_T. hebetans_) reaches the south coast of
+England. They attain to a width of from two to three feet, and
+specimens of that size are able to disable by a single discharge a
+full-grown man, and, therefore, may prove dangerous to bathing persons.
+Other genera, differing from _Torpedo_ in the position and structure of
+some of the fins, are found in other tropical and sub-tropical seas,
+viz. _Narcine_, _Hypnos_, _Discopyge_ (Peru), _Astrape_, and _Temera_.
+All, like electric fishes generally, have a naked body.
+
+A large fish, of the general appearance of a Torpedo, has been found at
+Monte Bolca; and _Cyclobatis_, from the upper cretaceous limestone of
+Lebanon, is probably another extinct representative of this family.
+
+
+                        FOURTH FAMILY--RAJIDÆ.
+
+_Disk broad, rhombic, generally with asperities or spines; tail with
+a longitudinal fold on each side. The pectoral fins extend to the
+snout. No electric organ; no serrated caudal spine._
+
+   RAJA.--Two dorsal fins on the tail, without spine; tail with
+   a rudimentary caudal fin, or without caudal. Each ventral fin
+   divided into two by a deep notch. Teeth small, obtuse, or
+   pointed. Pectoral fins not extending forwards to the extremity
+   of the snout. Nasal valves separated in the middle, where they
+   are without a free margin (see Fig. 1, p. 34).
+
+  [Illustration: Fig. 126.--Raja lemprieri, from Tasmania.]
+
+  [Illustration: Fig. 127.--Dermal spines of a male Thornback, Raja
+  clavata.]
+
+Of all the genera of _Batoidei_, Rays have the widest geographical
+range; they are chiefly inhabitants of temperate seas, and much more
+numerous in those of the Northern than of the Southern Hemisphere.
+They advance more closely to the Arctic and Antarctic circles than
+any other member of this group. More than thirty species are known,
+of which the following are found on the British coast:--The Thornback
+(_R. clavata_), the Homelyn Ray (_R. maculata_), the Starry Ray (_R.
+radiata_), the Sandy Ray (_R. circularis_), the common Skate (_R.
+batis_), the Burton Skate (_R. marginata_), and the Shagreen Skate (_R.
+fullonica_). Some of these species, especially the Skates, attain a
+considerable size, the disk measuring six and even seven feet across.
+All are eatable, and some of them regularly brought to market. In the
+majority of the species peculiar sexual differences have been observed.
+In some, as in the Thornback, all or some of the teeth are pointed
+in the male sex, whilst they are obtuse and flat in the female. The
+males of all are armed with patches of claw-like spines, retractile in
+grooves of the integument, and serially arranged occupying a space on
+the upper side of the pectoral fin near the angle of the disk, and
+frequently also the sides of the head. In species which are armed with
+bucklers or asperities it is the female which is principally provided
+with these dermal productions, the male being entirely or nearly
+smooth. Also the colour is frequently different in the two sexes.
+
+Other genera of this family are _Psammobatis_, _Sympterygia_, and
+_Platyrhina_. Although probably this family was well represented in
+cretaceous and tertiary formations, the remains found hitherto are
+comparatively few. _Arthropterus_, from the Lias, seems to have been a
+true Ray; and dermal spines of a species allied to the Thornback (_Raja
+antiqua_) are abundant in the crag deposits of Suffolk and Norfolk.
+
+
+                       FIFTH FAMILY--TRYGONIDÆ.
+
+_The pectoral fins are uninterruptedly continued to, and confluent
+at, the extremity of the snout. Tail long and slender, without lateral
+longitudinal folds; vertical fins none, or imperfectly developed, often
+replaced by a strong serrated spine._
+
+The “Sting-Rays” are as numerous as the Rays proper, but they inhabit
+rather tropical than temperate seas. The species armed with a spine
+use it as a weapon of defence, and the wounds inflicted by it are, to
+man, extremely painful, and have frequently occasioned the loss of a
+limb. We have mentioned above (p. 190) that the danger arises from the
+lacerated nature of the wound as well as from the poisonous property of
+the mucus inoculated. The spines (Fig. 98, p. 190) are always barbed on
+the sides, and may be eight or nine inches long in the larger species.
+They are shed from time to time, and replaced by others growing behind
+the one in function, as the teeth of the fishes of this order, or as
+the fangs of a poisonous snake. Fossil species of _Trygon_ and
+_Urolophus_ occur in the tertiary strata of Monte Bolca and Monte
+Postale. The genera into which the various species have been divided
+are the following:--
+
+   UROGYMNUS.--Tail long, without fin or spine, sometimes with a
+   narrow cutaneous fold below. Body densely covered with osseous
+   tubercles. Teeth flattened.
+
+Only one species is known (_U. asperrimus_), common in the Indian
+Ocean, and with a body from 4 to 5 feet long; the skin is frequently
+used for covering shields and the handles of swords and other weapons,
+its rough surface offering a firm hold to the hand.
+
+   TRYGON.--Tail very long, tapering, armed with a long
+   arrow-shaped barbed spine. Body smooth or with tubercles. Nasal
+   valves coalescent into a quadrangular flap. Teeth flattened.
+
+Some twenty-five species are known, one of which (_T. pastinaca_)
+extends from the south coast of England and the east coast of North
+America through the Atlantic and Indian Ocean to Japan. The majority
+of the species belong to the tropical parts of the Indian and Atlantic
+Oceans; some inhabit exclusively freshwaters of eastern tropical
+America. A closely allied genus is _Tæniura_, with six species.
+
+   UROLOPHUS.--Tail of moderate length, with a distinct rayed
+   terminal fin, armed with a barbed spine, without or with a
+   rudimentary dorsal fin. Teeth flattened.
+
+Seven species from tropical seas, apparently of small size.
+
+  [Illustration: Fig. 128.--Urolophus cruciatus, from Australia.]
+
+   PTEROPLATEA.--Body at least twice as broad as long; tail very
+   short and thin, without or with a rudimentary fin, and with a
+   serrated spine. Teeth very small, uni- or tri-cuspid.
+
+Six species from temperate and tropical seas.
+
+
+                      SIXTH FAMILY--MYLIOBATIDÆ.
+
+_The disk is very broad, in consequence of the great development of
+the pectoral fins, which, however, leave the sides of the head free,
+and reappear at the extremity of the snout as a pair of detached
+(cephalic) fins. Viviparous._
+
+“Devil-fishes,” “Sea-devils,” or “Eagle-rays.” Generally of large
+size, inhabiting temperate and tropical seas. Some genera possess a
+pair of singular cephalic processes, which generally project in a
+direction parallel to the longitudinal axis of the body, but are said
+to be flexible in the living fish, and used for scooping food from the
+bottom and conveying it to the mouth. In all the species the dentition
+consists of perfectly flat molars, forming a kind of mosaic pavement in
+both the upper and lower jaws: a most perfect mechanical arrangement
+for crushing alimentary substances.
+
+  [Illustration: Fig. 129.--Jaws of an Eagle-Ray, _Myliobatis
+  aquila._]
+
+   MYLIOBATIS.--Teeth sexangular, large, flat, tessellated, those
+   in the middle much broader than long; several narrower series
+   on each side. Tail very long and thin, with a dorsal fin near
+   its root; generally a serrated spine behind the fin.
+
+Seven species are known, two of which are European, one (_M. aquila_)
+being almost cosmopolitan, and occasionally found on the British coast.
+The young differ much from the adult, having no median series of larger
+teeth, but all the teeth of equal size and regularly sexangular. Also
+the tail is much longer in young examples than in old ones, and the
+coloration more ornamental. Teeth of species very closely allied to, or
+perhaps even identical with, existing species, are found in tertiary
+formations.
+
+   AËTOBATIS.--Form of the head, body, and tail as _Myliobatis_.
+   The nasal valves remain separate, each forming a long flap.
+   The lower dental lamina projects beyond the upper. Teeth flat,
+   broad, forming a single series, equivalent to the median series
+   of _Myliobatis_, there being no small lateral teeth.
+
+  [Illustration: Fig. 130.--Aëtobatis narinari.]
+
+One species only (_A. narinari_) which is found in almost all tropical
+seas, and of exceedingly common occurrence in the Atlantic and Indian
+Oceans; it does not seem to grow to a very large size (perhaps not
+exceeding 5 feet in width), and is readily recognised by numerous round
+bluish-white spots, with which the back is ornamented. Fossils of this
+genus occur in the English Eocenes and the Swiss Molasse.
+
+  [Illustration: Fig. 131.--Aëtobatis subarcuatus, from
+  Bracklesham.]
+
+RHINOPTERA.--The cephalic appendages are bent inwards, and situated
+at the lower side of the snout. Nasal valves confluent into a broad
+flap, with free margin. Teeth broad, flat, tessellated, in five or
+more series, the middle being the broadest, and the others decreasing
+in width outwards. Tail very slender, with a dorsal fin before the
+serrated spine.
+
+  [Illustration: Fig. 132.--Rhinoptera woodwardi; fossil.]
+
+  [Illustration: Fig. 133.--Rhinoptera polyodon.]
+
+Seven species from tropical and sub-tropical seas are known; of
+_Rhinoptera polyodon_ nothing is known except the jaws; and as its
+dentition is very peculiar, no opportunity should be lost of obtaining
+and preserving entire animals. Teeth very similar to those of existing
+species, and described as _Zygobatis_, occur in the Norwich Crag
+and in Miocene formations of Switzerland.
+
+   DICEROBATIS (CEPHALOPTERA).--Cephalic appendages pointing
+   straight forwards or inwards. Nostrils widely separated from
+   each other. Mouth inferior, wide. Both jaws with very numerous
+   and very small flat or tubercular teeth. Tail very slender,
+   with a dorsal fin between the ventrals, and with or without a
+   serrated spine.
+
+   CERATOPTERA.--Cephalic appendages pointing forwards or inwards.
+   Mouth anterior; wide. Teeth in the lower jaw only, very small.
+   Tail very slender, with a dorsal fin between the ventrals and
+   without spine.
+
+  [Illustration: Fig. 134.--Dicerobatis draco, from Misol.]
+
+The species of these two last genera are not yet well distinguished;
+about five of _Dicerobatis_ and two of _Ceratoptera_ are known from
+tropical and temperate seas, but their occurrence in the latter is
+rather sporadic. Some of them, if not all, attain an enormous size.
+One mentioned by Risso, taken off Messina, weighed 1250 pounds.
+Several observers speak of having seen them in pairs, the male being
+usually the smaller. Of a pair mentioned by Risso the female was first
+taken, and the male remained hovering about the boat for three days,
+and was afterwards found floating dead on the surface. Still larger
+individuals, but of uncertain species, are mentioned by Lacépède, who
+says that one taken at Barbadoes required seven yoke of oxen to draw
+it. A sketch of another, which was said to be twenty feet long, was
+sent to Lacépède; and Sonnini speaks of one which appeared to him to be
+longer and wider than the ship in which he was sailing. A fœtus taken
+from the uterus of the mother captured at Jamaica, and preserved in
+the British Museum, is five feet broad, and weighed twenty pounds. The
+mother measured fifteen feet in width as well as in length, and was
+between three and four feet thick. The capture of “Devil-fishes” of
+such large size is attended with danger, as they not rarely attack and
+capsize the boat. They are said to be especially dangerous when they
+accompany their young, of which they bring forth one only at a time.
+
+
+                    SECOND SUB-ORDER--HOLOCEPHALA.
+
+_One external gill-opening only, covered by a fold of the skin, which
+encloses a rudimentary cartilaginous gill-cover; four branchial clefts
+within the gill-cavity. The maxillary and palatal apparatus coalescent
+with the skull._
+
+This suborder is represented in the living fauna by one family only,
+_Chimæridæ_; it forms a passage to the following order of fishes, the
+Ganoids. In external appearance, and with regard to the structure of
+their organs of propagation, the Chimæras are Sharks (See Fig. 96, p.
+184). The males are provided with “claspers” in connection with the
+ventral fins, and the ova are large, encased in a horny capsule, and
+few in number; and there is no doubt that they are impregnated within
+the oviduct, as in Sharks. Chimæras are naked, but, as in _Scylliidæ_,
+very young individuals possess a series of small “placoid” spines,
+which occupy the median line of the back, and remind us of similar
+dermal productions in the Rays. The males, besides, are provided with
+a singular erectile appendage, spiny at its extremity, and received
+in a groove on the top of the head. On the other hand, the relations
+of the Chimæras to the Ganoid, and, more especially, Dipnoous type
+become manifest in their notochordal skeleton and continuity of
+cranial cartilage. The spine in front of the first dorsal fin is
+articulated to the neural apophysis, and not merely implanted in the
+soft parts, and immovable as in Sharks. A cartilaginous operculum
+makes its appearance, and the external gill-opening is single. The
+dentition is that of a Dipnoid, each “jaw” being armed with a pair of
+broad dental plates, with the addition of a pair of smaller cutting
+teeth in the upper “jaw.” Fossils of similar dental combination are
+not rare in strata, commencing from the Lias and the bottom of the
+Oolitic series; but it is impossible to decide in every case whether
+the fossil should be referred to the Holocephalous or Dipnoous type.
+According to Newberry, Chimæroid fishes commence in the Devonian with
+_Rhynchodus_, the remains of which were discovered by him in Devonian
+rocks of Ohio. Undoubted Chimæroids are _Elasmodus_, _Psaliodus_,
+_Ganodus_, _Ischyodus_, _Edaphodon_, and _Elasmognathus_, principally
+from mesozoic and tertiary formations. Very similar fossils occur
+in the corresponding strata of North America. A single species of
+_Callorhynchus_ has been discovered by H. Hector in the Lower Greensand
+of New Zealand.
+
+The living Chimæras are few in number, and remain within very moderate
+dimensions, probably not exceeding a length of five feet, inclusive
+of their long filamentous, diphycercal tail. They are referred to two
+genera.
+
+   CHIMÆRA.--Snout soft, prominent, without appendage. The dorsal
+   fins occupying the greater part of the back, anterior with
+   a very strong and long spine. Longitudinal axis of the tail
+   nearly the same as that of the trunk, its extremity being
+   provided with a low fin above and below, similar in form to a
+   dorsal and anal fin. Anal fin very low.
+
+Three species are known: _Ch. monstrosa_, from the coasts of Europe and
+Japan and the Cape of Good Hope; _Ch. colliei_ from the west coast of
+North America; and _Ch. affinis_ from the coast of Portugal. (See Fig.
+96, p. 184.)
+
+   CALLORHYNCHUS.--Snout with a cartilaginous prominence,
+   terminating in a cutaneous flap. Two dorsal fins, the anterior
+   with a very strong and long spine. Extremity of the tail
+   distinctly turned upwards, with a fin along its lower edge, but
+   without one above. Anal fin close to the caudal, short and deep.
+
+One species (_C. antarcticus_) is common in the Southern temperate
+zone. Cunningham describes the egg (see Fig. 81, p. 169), as being of
+a dark greenish-black colour, and, in general, measuring from eight
+to nine or even ten inches in length, by about three in breadth. It
+consists of a central, somewhat spindle-shaped convex area (between
+the horny walls of which the young fish lies), surrounded by a broad
+plicated margin, which is fringed at the edge, and covered on the under
+surface with fine light brownish-yellow hairs.
+
+
+                        SECOND ORDER--GANOIDEI.
+
+_Skeleton cartilaginous or ossified. Body with medial and paired
+fins, the hinder pair abdominal. Gills free, rarely partially attached
+to the walls of the gill-cavity. One external gill-opening only on
+each side; a gill-cover. Air-bladder with a pneumatic duct. Ova small,
+impregnated after exclusion. Embryo sometimes with external gills._
+
+To this order belong the majority of the fossil fish remains of
+palæozoic and mesozoic age, whilst it is very scantily represented
+in the recent fauna, and evidently verging towards total extinction.
+The knowledge of the fossil forms, based on mere fragments of the
+hard parts of the body only, is very incomplete, and therefore their
+classification is in a most unsatisfactory state. In the following
+pages only the most important groups will be mentioned.
+
+   [For a study of details we have to refer to _Agassiz_, “Poissons
+   Fossiles;” _Owen_, “Palæontology,” Edinb. 1861, 8vo; _Huxley_,
+   “Preliminary Essay upon the Systematic Arrangement of the Fishes
+   of the Devonian Epoch,” in Mem. Geolog. Survey, Dec. 10; Lond.
+   1861, and “Illustrations of the Structure of Crossopterygian
+   Ganoids,” _ibid._ December 12, 1866; _Traquair_, “The Ganoids of
+   the British Carboniferous Formations,” part I. “Palæoniscidæ.”
+   Palæontogr. Soc. Lond. 1877.]
+
+Eight suborders may be distinguished at present.
+
+
+                     FIRST SUB-ORDER--PLACODERMI.
+
+_Extinct. The head and pectoral region of the body encased in great
+bony, sculptured plates, with dots of enamel; the remainder of the body
+naked, or with ganoid scales; skeleton notochordal._
+
+Comprises the oldest vertebrate remains, from Devonian and
+Carboniferous formations. _Pterichthys_: (Figs. 135 and 136), tail
+tapering, covered with small ganoid scales, without caudal fin; the
+cephalic shield was probably moveably joined to the cuirass of the
+trunk, and both were composed of several pieces; the abdominal shield
+consisted of one single median plate, and two pairs of lateral plates,
+a third small pair being sometimes observed detached in front of the
+anterior pair; pectoral exceedingly long, consisting of two pieces
+movably connected with each other; tail scaly, and short; a small
+dorsal fin placed on the tail; a pair of small ventrals; jaws small,
+with confluent denticles. Several species have been distinguished
+in remains found in the strata of Caithness and other localities in
+Scotland. _Coccosteus_ (Fig. 137, p. 354): all the bony plates are
+firmly united, no pectoral spines; tail naked and long; a dorsal and
+anal fin supported by interneural and interhæmal spines. Dentition
+unknown. _Dinichthys_: a gigantic fish from the Devonian of North
+America (estimated at from 15 to 18 feet in length), with the dermal
+covering very similar to that of Coccosteus, but with a simple arched
+dorsal shield. As in this latter genus the caudal extremity does not
+possess external or internal bony parts, and the ventral plastron
+of both genera corresponds in every particular; the dentition is so
+singularly like that of Lepidosiren, that Newberry (Geolog. Survey of
+Ohio, vol. ii. part 2) considers this genus to be in genetic relation
+to the Dipnoi. The following genera have been united in a separate
+family, _Cephalaspidæ_; viz. _Cephal__aspis_: head covered by a
+continuous shield with tubercular surface, produced into a horn at each
+posterior corner; a median dorsal backward prolongation bears a spine;
+heterocercal. _Auchenaspis_ and _Didymaspis_: allied to the preceding,
+but with the cephalic shield divided into a larger anterior and smaller
+posterior piece. _Pteraspis_: with the cephalic shield finely striated
+or grooved, composed of seven pieces. _Scaphaspis_ and _Cyathaspis_:
+with the surface of the head-shield similarly sculptured as in
+_Pteraspis_, but simple in the former, and composed of four pieces in
+the latter. _Astrolepis_: attained to the gigantic size of between
+twenty and thirty feet; its mouth was furnished with two rows of teeth,
+of which the outer ones were small, the inner much larger.
+
+   [See Ray Lankester, A. Monograph of the Fishes of the Old Red
+   Sandstone of Britain. Part I. Cephalaspidæ. Lond. 1868 and 1870.
+   4to.]
+
+  [Illustration: Fig. 135.--Dorsal surface of Pterichthys, after
+  Pander. _d_, Dorsal fin; _c_, pectoral member; 2–10,
+  head-bucklers; 11–13, dorsal bucklers.]
+
+  [Illustration: Fig. 136.--Ventral aspect of Pterichthys, after
+  Pander. 15, mandible (?); 16–21, ventral bucklers.]
+
+  [Illustration: Fig. 137.--Coccosteus, after Pander. _A_, Anal
+  fin; _D_, Dorsal fin; _C_, Heterocercal tail; _c_, notochord;
+  _n_, neurals; _h_, hæmals; 6–24, bucklers.]
+
+
+                    SECOND SUB-ORDER--ACANTHODINI.
+
+Extinct. _Body oblong, compressed, covered with shagreen; skull
+not ossified; caudal heterocercal. Large spines, similar to those of
+Chondropterygians, in front of some of the median and paired fins.
+The spines are imbedded between the muscles, and not provided with a
+proximal joint._
+
+_Acanthodes_, _Chiracanthus_, from Devonian and Carboniferous
+formations.
+
+
+                       THIRD SUB-ORDER--DIPNOI.
+
+_Nostrils two pairs, more or less within the mouth; limbs with
+an axial skeleton. Lungs and gills. Skeleton notochordal. No
+branchiostegals._[38]
+
+
+                        FIRST FAMILY--SIRENIDÆ.
+
+_Caudal fin diphycercal; no gular plates; scales cycloid. A pair of
+molars, above and below, and one pair of vomerine teeth._
+
+   LEPIDOSIREN.--Body eel-shaped, with one continuous vertical fin.
+   Limbs reduced to cylindrical filaments, without fringe. Vomerine
+   teeth conical, pointed. Each dental lamina or molar with strong
+   cusps, supported by vertical ridges. No external branchial
+   appendages; five branchial arches, with four intervening clefts.
+   Conus arteriosus with two longitudinal valves. Ovaries closed
+   sacs.
+
+One species only is known from the system of the River Amazons (_L.
+paradoxa_). It must be very locally distributed, as but a few
+specimens have been brought to Europe, and all recent endeavours to
+obtain others have been unsuccessful. Natterer, by whom this most
+interesting fish was discovered, states that he obtained two specimens,
+one on the Madeira River, near Borba; the other in a backwater of the
+Amazons, above Villa Nova. The natives of the former place called it
+Carámurú, and considered it very scarce. The larger individual was
+nearly four feet long. It is said to produce a sound not unlike that
+of a cat, and to feed on the roots of mandioca and other vegetables.
+But, to judge from the dentition, this fish is much more likely to be
+carnivorous, like the following. It is one of the greatest desiderata
+of Natural History Collections.
+
+   [Natterer, “Annalen des Wiener Museum’s,” 1839, ii.; Bischoff.
+   “Annales des Sciences Naturelles,” 1840. xiv.]
+
+   PROTOPTERUS.--Very similar in the general form of the body and
+   dentition to _Lepidosiren_. Pectoral and ventral filaments with
+   a fringe containing rays. Three small branchial appendages
+   above the small gill-opening; six branchial arches, with five
+   intervening clefts. Conus arteriosus with two longitudinal
+   valves. Ovaries closed sacs.
+
+_Protopterus annectens_ is the “Lepidosiren” which is commonly found in
+Zoological collections. It is usually imported from the west coast of
+Africa, where it abounds in many localities; but it is spread over the
+whole of tropical Africa, and forms in many districts of the central
+parts a regular article of food.
+
+  [Illustration: Fig. 138.--Protopterus annectens. _g_,
+  Branchial filaments; _v_, vent.]
+
+During the dry season, specimens living in shallow waters which
+periodically dry up, form a cavity in the mud, the inside of which they
+line with a protecting capsule of mucus, and from which they emerge
+again when the rains refill the pools inhabited by them. Whilst they
+remain in this torpid state of existence, the clay-balls containing
+them are frequently dug out, and if the capsules are not broken, the
+fishes imbedded in them can be transported to Europe, and released
+by being immersed in slightly tepid water. _Protopterus_ is
+exclusively carnivorous, feeding on water-insects, frogs, and fishes,
+and attains a length of six feet.
+
+    [Owen, “Trans. Linn. Soc.” 1841, xviii.]
+
+   CERATODUS.--Body elongate, compressed, with one continuous
+   vertical fin. Limbs paddle-shaped, with broad, rayed fringe.
+   Vomerine teeth incisor-like; molars with flat, undulated
+   surface, and lateral prongs. No external branchial appendages.
+   Conus arteriosus with transverse series of valves. Ovaries
+   transversely lamellated.[39]
+
+  [Illustration: Fig. 139.--_Ceratodus miolepis._]
+
+Two species, _C. forsteri_ and _C. miolepis_, are known from fresh
+waters of Queensland. The specimens hitherto obtained have come from
+the Burnett, Dawson, and Mary rivers, some from the fresh waters of
+the upper parts, others from the lower brackish portions. The fish is
+said to attain to a weight of twenty pounds and to a length of 6 feet.
+Locally, the settlers call it “Flat-head,” “Burnett- or Dawson-Salmon,”
+and the aborigines “Barramunda,” a name which they appear to apply
+also to other large-scaled freshwater fishes, as the Osteoglossum
+leichardti. In the stomach there is generally found an enormous
+quantity of the leaves of plants growing on the banks of rivers,
+evidently eaten after they had fallen into the water and when in a
+decomposing condition. The flesh of the fish is salmon-coloured, and
+much esteemed as food.
+
+The Barramunda is said to be in the habit of going on land, or at least
+on mud-flats; and this assertion appears to be borne out by the fact
+that it is provided with a lung. However, it is much more probable
+that it rises now and then to the surface of the water in order to
+fill its lung with air, and then descends again until the air is so
+much deoxygenised as to render a renewal of it necessary. It is also
+said to make a grunting noise, which may be heard at night for some
+distance. This noise is probably produced by the passage of the air
+through the œsophagus when it is expelled for the purpose of renewal.
+As the Barramunda has perfectly developed gills, beside the lung, we
+can hardly doubt that, when it is in water of normal composition,
+and sufficiently pure to yield the necessary supply of oxygen, these
+organs are sufficient for the purpose of breathing, and that the
+respiratory function rests with them alone. But when the fish is
+compelled to sojourn in thick muddy water charged with gases, which are
+the products of decomposing organic matter (and this must be the case
+very frequently during the droughts which annually exhaust the creeks
+of tropical Australia), it commences to breathe air with its lung in
+the way indicated above. If the medium in which it happens to be is
+perfectly unfit for breathing the gills cease to have any function;
+if only in a less degree the gills may still continue to assist in
+respiration. The Barramunda, in fact, can breathe by either gills or
+lungs alone, or by both simultaneously. It is not probable that it
+lives freely out of the water, its limbs being much too flexible for
+supporting the heavy and unwieldy body, and too feeble generally to be
+of much use in locomotion on land. However, it is quite possible that
+it is occasionally compelled to leave the water, although we cannot
+believe that it can exist without it in a lively condition for any
+length of time.
+
+Of its propagation or development we know nothing, except that it
+deposits a great number of eggs of the size of those of a newt, and
+enveloped in a gelatinous case. We may infer that the young are
+provided with external gills, as in Protopterus and Polypterus.
+
+  [Illustration: Fig. 140.--Tooth of fossil _Ceratodus_ from
+  Aust., near Bristol, natural size.]
+
+The discovery of _Ceratodus_ does not date farther back than the year
+1870, and proved to be of the greatest interest, not only on account
+of the relation of this creature to the other living _Dipnoi_ and
+_Ganoidei_, but also because it threw fresh light on those singular
+fossil teeth which are found in strata of Triassic and Jurassic
+formations in various parts of Europe, India, and America. These teeth,
+of which there is a great variety with regard to general shape and
+size, are sometimes two inches long, much longer than broad, depressed,
+with a flat or slightly undulated, always punctated crown, with one
+margin convex, and with from three to seven prongs projecting on the
+opposite margin.
+
+  [Illustration: Fig. 141.--Dipterus macrolepidotus.]
+
+
+                   SECOND FAMILY--CTENODODIPTERIDÆ.
+
+_Caudal fin heterocercal. Gular plates. Scales cycloid. Two pairs of
+molars and one pair of vomerine teeth._
+
+Extinct. _Dipterus_ (_Ctenodus_), _Heliodus_ from Devonian strata.
+
+
+                    THIRD FAMILY--PHANEROPLEURIDÆ.
+
+_Caudal fin diphycercal; vertical fin continuous. Gular plates.
+Scales cycloid. Jaws with a series of minute conical teeth on the
+margin._
+
+Extinct. _Phaneropleuron_ from Devonian formations, and the
+carboniferous _Uronemus_ are probably generically identical.
+
+
+                    FOURTH SUB-ORDER--CHONDROSTEI.
+
+_Skeleton notochordal; skull cartilaginous, with dermal ossifications;
+branchiostegals few in number or absent. Teeth minute or absent.
+Integuments naked or with bucklers. Caudal fin heterocercal, with
+fulcra. Nostrils double, in front of the eyes._
+
+
+                      FIRST FAMILY--ACIPENSERIDÆ.
+
+_Body elongate, sub-cylindrical, with five rows of osseous bucklers.
+Snout produced, subspatulate or conical, with the mouth at its lower
+surface, small, transverse, protractile, toothless. Four barbels in a
+transverse series on the lower side of the snout. Vertical fins with
+a single series of fulcra in front. Dorsal and anal fins approximate
+to the caudal. Gill-membranes confluent at the throat and attached to
+the isthmus. Branchiostegals none. Gills four; two accessory gills.
+Air-bladder large, simple, communicating with the dorsal wall of the
+œsophagus._
+
+  [Illustration: Fig. 142.--Tail of Acipenser. _a_, Fulcra;
+  _b_, osseous bucklers.]
+
+Sturgeons are, perhaps, the geologically youngest Ganoids, evidence
+of their existence not having been met with hitherto in formations
+of older date than the Eocene clay of Sheppey. They are exclusively
+inhabitants of the temperate zone of the Northern Hemisphere, being
+either entirely confined to fresh water, or passing, for the purpose of
+spawning, a part of the year in rivers. They grow to a large size, and
+are the largest fishes of the fresh waters of the Northern Hemisphere,
+specimens 10 feet long being of common occurrence. The ova are very
+small, and so numerous that one female has been calculated to produce
+about three millions at one season; therefore their propagation, as
+well as their growth, must be very rapid; and although in many rivers
+their number is annually considerably thinned by the systematic manner
+in which they are caught when they ascend the rivers in shoals from the
+sea, no diminution has been observed. Wherever they occur they prove
+to be most valuable on account of their wholesome flesh. In Russia,
+besides, two not unimportant articles of trade are obtained from them,
+viz. Caviare, which is prepared from their ovaries, and Isinglass,
+which is made from the inner coats of their air-bladder. True Sturgeons
+are divided into two genera, _Acipenser_ and _Scaphirhynchus_.
+
+   ACIPENSER.--The rows of osseous bucklers are not confluent
+   on the tail. Spiracles present. Caudal rays surrounding the
+   extremity of the tail.
+
+About twenty different species of Sturgeons may be distinguished from
+European, Asiatic, and American rivers. The best known are the Sterlet
+(_A. ruthenus_) from Russian rivers, celebrated for the excellency of
+its flesh, but rarely exceeding a length of three feet; the Californian
+Short-snouted Sturgeon (_A. brachyrhynchus_); the Hausen (_A. huso_),
+from rivers, falling into the Black Sea and the Sea of Azow (rare
+in Mediterranean), sometimes 12 feet long, and yielding an inferior
+kind of isinglass; the Chinese Sturgeon (_A. sinensis_); the Common
+Sturgeon of the United States (_A. maculosus_), which sometimes crosses
+the Atlantic to the coasts of Great Britain; Güldenstædt’s Sturgeon
+(_A. güldenstædtii_), common in European and Asiatic rivers, which
+yields more than one-fourth of the caviare and isinglass exported from
+Russia; the Common Sturgeon of Western Europe (_A. sturio_), which
+attains to a length of 18 feet, and has established itself also on the
+coasts of Eastern North America.
+
+   SCAPHIRHYNCHUS.--Snout spatulate; posterior part of the tail
+   attenuated and depressed, so that it is entirely enveloped by
+   the osseous scutes. Spiracles none. The caudal rays do not
+   extend to the extremity of the tail, which terminates in a
+   filament.
+
+Four species are known: one (_S. platyrhynchus_) from the
+river-system of the Mississippi, and the three others from Central
+Asia; all are exclusively freshwater fishes; their occurrence in so
+widely distant rivers is one of the most striking instances by which
+the close affinity of the North American and North Asiatic faunas is
+proved.
+
+
+                     SECOND FAMILY--POLYODONTIDÆ.
+
+_Body naked, or with minute stellate ossifications. Mouth lateral,
+very wide, with minute teeth in both jaws. Barbels none. Caudal fin
+with fulcra. Dorsal and anal fins approximate to the caudal. Four gills
+and a half; no opercular gill or pseudobranchia._
+
+   POLYODON (SPATULARIA).--The snout is produced into an
+   exceedingly long, shovel-like process, thin and flexible on
+   the sides. Spiracles present. Gill-cover terminating in a very
+   long tapering flap. One broad branchiostegal. Each branchial
+   arch with a double series of very long, fine, and numerous
+   gill-rakers, the two series being divided by a broad membrane.
+   Air-bladder cellular. Upper caudal fulcra narrow, numerous.
+
+The single species, _P. folium_, occurs in the Mississippi, and grows
+to a length of about six feet, of which the rostral shovel takes about
+one-fourth; in young examples it is comparatively still longer.
+
+   PSEPHURUS differs from _Polyodon_ in having the rostral
+   process less depressed and more conical. The gill-rakers are
+   comparatively short, in moderate number, and distant from one
+   another. Upper caudal fulcra enormously developed, and in small
+   number (six).
+
+_Psephurus gladius_ inhabits the Yan-tse-Kiang and Hoangho, the
+distribution of the _Polyodontidæ_ being perfectly analogous to
+that of _Scaphirhynchus_. It grows to an immense size, specimens
+of 20 feet in length being mentioned by Basilewsky. The function of the
+rostral process in the economy of these fishes is not yet sufficiently
+explained. Martens believes that it serves as an organ of feeling,
+the water of those large Asiatic and American rivers being too turbid
+to admit of the Sturgeon seeing its prey, which consists of other
+fishes. The eyes of _Psephurus_, as well as _Polyodon_, are
+remarkably small. Both fishes are used as food.
+
+  [Illustration: Fig. 143.--Psephurus gladius.]
+
+Allied to the _Polyodontidæ_, and likewise provided with a
+paddle-shaped production of the fore part of the head, is the fossil
+genus _Chondrosteus_, remains of which occur in the Lias.
+
+
+                    FIFTH SUB-ORDER--POLYPTEROIDEI.
+
+_Paired fins with axial skeleton, fringed; dorsal fins two or more.
+Branchiostegals absent, but generally gular plates. Vertebral column
+diphycercal or heterocercal. Body scaly._
+
+
+                      FIRST FAMILY--POLYPTERIDÆ.
+
+_Scales ganoid; fins without fulcra. A series of dorsal spines, to
+each of which an articulated finlet is attached; anal placed close to
+the caudal fin, the vent being near the end of the tail. Abdominal
+portion of the vertebral column much longer than the caudal._
+
+   POLYPTERUS.--Teeth rasp-like, in broad bands in the jaws, on
+   the vomer and palatine bones; jaws with an outer series of
+   closely-set, larger, pointed teeth. Caudal fin surrounding the
+   extremity of the vertebral column; ventral fins well developed.
+   A spiracle on each side of the parietal, covered with an
+   osseous plate. A single large gular plate. Air-bladder double,
+   communicating with the ventral wall of the pharynx.
+
+  [Illustration: Fig. 144.--Polypterus bichir.]
+
+This Ganoid is confined to tropical Africa, occurring in abundance in
+the rivers of the west coast and in the Upper Nile; but it has not
+been found in the river-systems belonging to the Indian Ocean. It is
+scarce in the Middle and Lower Nile, and the specimens found below the
+Cataracts have been carried down, from southern latitudes, and do not
+propagate their species in that part of the river. There is only one
+species known, _Polypterus bichir_ (“Bichir” being its vernacular
+name in Egypt), which varies in the number of the dorsal finlets,
+the lowest being eight, the highest eighteen. It attains to a length
+of four feet. Nothing is known of its mode of life, and observations
+thereon are very desirable.
+
+   CALAMOICHTHYS.--Distinguished from _Polypterus_ by its greatly
+   elongate form, and the absence of ventral fins.
+
+_C. calabaricus_, a dwarf form from Old Calabar.
+
+
+                    SECOND FAMILY--SAURODIPTERIDÆ.
+
+_Scales ganoid, smooth like the surface of the skull. Two dorsal fins;
+paired fins obtusely lobate. Teeth conical. Caudal heterocercal._
+
+Extinct. _Diplopterus_, _Megalichthys_, and _Osteolepis_ from Devonian
+and Carboniferous formations.
+
+
+                     THIRD FAMILY--COELACANTHIDÆ.
+
+_Scales cycloid. Two dorsal fins, each supported by a single
+two-pronged interspinous bone; paired fins obtusely lobate. Air-bladder
+ossified; notochord persistent, diphycercal._
+
+Extinct. _Coelacanthus_ from carboniferous strata; several other
+genera, from the coal formations to the chalk, have been associated
+with it--_Undina_, _Graphiurus_, _Macropoma_, _Holophagus_,
+_Hoplopygus_, _Rhizodus_.
+
+
+                     FOURTH FAMILY--HOLOPTYCHIIDÆ.
+
+_Scales cycloid or ganoid, sculptured. Two dorsal fins; pectorals
+narrow, acutely lobate; dentition dendrodont._
+
+Extinct. In this family a peculiar type of dentition is found--the
+jaws are armed with two kinds of teeth, small ones serially arranged,
+and much larger fang-like teeth disposed at long intervals. Both kinds
+show at their base in transverse sections a labyrinthic complexity
+of structure, numerous fissures radiating from the central mass of
+vasodentine which fills up the pulp cavity, and sending off small
+ramifying branches. Genera belonging to this family are _Holoptychius_,
+_Saurichthys_, _Glyptolepis_, _Dendrodus_, _Glyptolaemus_,
+_Glyptopomus_, _Tristichopterus_, _Gyroptychius_, _Strepsodus_, from
+Devonian and Carboniferous strata.
+
+
+                   SIXTH SUB-ORDER--PYCNODONTOIDEI.
+
+_Body compressed, high and short or oval, covered with rhombic scales
+arranged in decussating pleurolepidal lines. Notochord persistent.
+Paired fins without axial skeleton. Teeth on the palate and hinder part
+of the lower jaw molar-like. Branchiostegals, but no gular plates._
+
+Extinct. The regular lozenge-shaped pattern of the integuments of these
+fishes is described by Sir P. Egerton thus: “Each scale bears upon its
+inner anterior margin a thick solid bony rib, extending upwards beyond
+the margin of the scale, and sliced off obliquely, above and below, on
+opposite sides, for forming splices with the corresponding processes
+of the adjoining scales. These splices are so closely adjusted that,
+without a magnifying power or an accidental dislocation, they are not
+perceptible. When _in situ_, and seen internally, these continuous
+lines decussate with the true vertebral apophyses.” In some genera the
+“pleurolepidal” lines are confined to the anterior part of the side.
+
+
+                      FIRST FAMILY--PLEUROLEPIDÆ.
+
+_Homocercal. Body less high. Fins with fulcra._
+
+_Pleurolepis_ and _Homoeolepis_ from the Lias.
+
+
+                     SECOND FAMILY--PYCNODONTIDÆ.
+
+_Homocercal. The neural arches and ribs are ossified; the roots of
+the ribs are but little expanded in the older genera, but enlarged in
+the tertiary forms, so as to simulate vertebræ. Paired fins not lobate.
+Obtuse teeth on the palate and the sides of the mandible; maxilla
+toothless; incisor-like teeth in the intermaxillary and front of the
+mandible. Fulcra absent in all the fins._
+
+These fishes abound in Mesozoic and Tertiary formations. _Gyrodus_,
+_Mesturus_, _Microdon_, _Coelodus_, _Pycnodus_, _Mesodon_, are some of
+the genera distinguished by palæontologists. (See Fig. 102, p. 201.)
+
+
+                  SEVENTH SUB-ORDER--LEPIDOSTEOIDEI.
+
+_Scales ganoid, rhombic; fins generally with fulcra; paired fins
+not lobate. Præ- and inter-operculum developed; generally numerous
+branchiostegals, but no gular plate._
+
+
+                      FIRST FAMILY--LEPIDOSTEIDÆ.
+
+_Scales ganoid, lozenge-shaped. Skeleton completely ossified;
+vertebræ convex in front and concave behind. Fins with fulcra; dorsal
+and anal composed of articulated rays only, placed far backwards, close
+to the caudal. Abdominal part of the vertebral column much longer
+than caudal. Branchiostegals not numerous, without enamelled surface.
+Heterocercal._
+
+   _Lepidosteus._--Body elongate, sub-cylindrical; snout elongate,
+   spatulate, or beak-shaped; cleft of the mouth wide; both jaws
+   and palate armed with bands of rasp-like teeth and series
+   of larger conical teeth. Four gills; no spiracles; three
+   branchiostegals. Air-bladder cellular, communicating with the
+   pharynx.
+
+  [Illustration: Fig. 145.--Lepidosteus viridis.]
+
+Fishes of this genus existed already in Tertiary times; their remains
+have been found in Europe as well as North America. In our period
+they are limited to the temperate parts of North America, Central
+America, and Cuba. Three species can be distinguished which attain
+to a length of about six feet. They feed on other fishes, and their
+general resemblance to a pike has given to them the vernacular names of
+“Gar-Pike,” or “Bony Pike.”
+
+
+                        SECOND FAMILY--SAURIDÆ.
+
+_Body oblong, with ganoid scales; vertebræ not completely ossified;
+termination of the vertebral column homocercal; fins generally with
+fulcra. Maxillary composed of a single piece; jaws with a single series
+of conical pointed teeth. Branchiostegals numerous, enamelled, the
+anterior broad gular plates._
+
+Extinct. Numerous genera occur in Mesozoic formations; one with the
+widest range is _Semionotus_, with distichous fulcra, from the Lias and
+Jura; _Eugnathus_, with large posteriorly serrated scales, and fulcra
+on nearly all fins; _Cephenoplosus_ from the Upper Lias; _Macrosemius_
+from the Oolite; _Propterus_, _Ophiopsis_, _Pholidophorus_,
+_Pleuropholis_, _Pachycormus_, _Oxygnathus_, _Ptycholepis_, _Conodus_,
+_Eulepidotus_, _Lophiostomus_, etc.
+
+
+                      THIRD FAMILY--STYLODONTIDÆ.
+
+_Body rhombic or ovate, with ganoid scales; vertebræ not completely
+ossified; termination of the vertebral column homocercal; fins with
+fulcra. Maxillary composed of a single piece; jaws with several series
+of teeth, the outer ones equal, styliform. Dorsal fin very long,
+extending to the caudal. Branchiostegals numerous._
+
+Extinct. _Tetragonolepis_ from the Lias (see Fig. 103, p. 207).
+
+
+                     FOURTH FAMILY--SPHÆRODONTIDÆ.
+
+_Body oblong, with rhombic ganoid scales; vertebræ ossified, but not
+completely closed; homocercal; fins with fulcra. Maxillary composed of
+a single piece; teeth in several series, obtuse; those on the palate
+globular. Dorsal and anal fins short. Branchiostegals._
+
+Extinct. The type genus of this family is _Lepidotus_, so named from
+its large rhombic, dense, and polished scales. The dorsal is opposite
+to the anal, and all the fins are provided with a double row of fulcra.
+This genus ranges from the Lias to the Chalk; one species would seem
+to have survived into tertiary times, if it should not prove to be a
+_Lepidosteus_.
+
+
+                    FIFTH FAMILY--ASPIDORHYNCHIDÆ.
+
+_Body elongate, with ganoid scales; jaws prolonged into a beak;
+termination of the vertebral column homocercal. Fins with fulcra;
+a series of enlarged scales along the side of the body. Dorsal fin
+opposite to the anal._
+
+  [Illustration: Fig. 146.--Aspidorhynchus fisheri, from the
+  Purbeck beds; _m_, mandible; _a_, presymphyseal bone.]
+
+Extinct; mesozoic. _Aspidorhynchus_ has the upper jaw longer than the
+lower; very peculiar is the occurrence of a single, solid, conical
+bone, situated in front of the symphysis of the lower jaw, to which it
+is joined by a suture. _Belonostomus_ with both jaws of equal length.
+
+
+                      SIXTH FAMILY--PALÆONISCIDÆ.
+
+_Body fusiform, with rhombic ganoid scales. Notochord persistent,
+with the vertebral arches ossified. Heterocercal. All the fins with
+fulcra; dorsal short. Branchiostegals numerous, the foremost pair
+forming broad gulars. Teeth small, conical, or cylindrical._
+
+Extinct. Many genera are known; from the Old Red
+Sandstone--_Chirolepis_ and _Acrolepis_; from Carboniferous
+rocks--_Cosmoptychius_, _Elonichthys_, _Nematoptychius_,
+_Cycloptychius_, _Microconodus_, _Gonatodus_, _Rhadinichthys_,
+_Myriolepis_, _Urosthenes_; from the Permian--_Rhabdolepis_,
+_Palæoniscus_, _Amblypterus_ and _Pygopterus_; from the
+Lias--_Centrolepis_, _Oxygnathus_, _Cosmolepis_, and _Thrissonotus_.
+
+   [See Traquair, “The Ganoid Fishes of the British Carboniferous
+   Formations.” Part I. _Palæoniscidæ._]
+
+
+                     SEVENTH FAMILY--PLATYSOMIDÆ.
+
+_Body generally high, compressed, covered with rhombic ganoid
+scales arranged in dorso-ventral bands. Notochord persistent, with
+the vertebral arches ossified. Heterocercal; fins with fulcra; dorsal
+fin long, occupying the posterior half of the back. Branchiostegals
+numerous. Teeth tubercular or obtuse._
+
+Extinct. From Carboniferous and Permian formations--_Eurynotus_,
+_Benedenius_, _Mesolepis_, _Eurysomus_, _Wardichthys_, _Chirodus_
+(M’Coy), _Platysomus_.
+
+    [See Traquair, “On the Structure and Affinities of the Platysomidæ”, in
+    “Trans. Roy. Soc.,” Edinb., vol. xxix.]
+
+[Illustration: Fig. 147.--Platysomus gibbosus.]
+
+
+                      EIGHTH SUB-ORDER--AMIOIDEI.
+
+_Vertebral column more or less completely ossified, heterocercal.
+Body covered with cycloid scales. Branchiostegals present._
+
+
+                        FIRST FAMILY--CATURIDÆ.
+
+_Notochord persistent, with partially ossified vertebræ; homocercal;
+fins with fulcra. Teeth in a single series, small, pointed._
+
+Extinct. _Caturus_ from the Oolite to the Chalk.
+
+  [Illustration: Fig. 148.--Caturus furcatus (Solenhofen).]
+
+
+                      SECOND FAMILY--LEPTOLEPIDÆ.
+
+_Scales cycloid. Vertebræ ossified; homocercal; fins without fulcra;
+dorsal short. Teeth minute, in bands, with canines in front._
+
+Extinct, and leading to the living representative of this suborder.
+_Thrissops_ with the dorsal fin placed far backwards, and opposite
+to the long anal. _Leptolepis_ with the dorsal fin opposite to the
+ventrals, from the Lias and Oolite. These fishes, as far as the
+preserved parts are concerned, cannot be distinguished from Teleosteous
+fishes, to which they are referred by some Palæontologists.
+
+  [Illustration: Fig. 149.--Leptolepis sprattiformis.]
+
+
+                         THIRD FAMILY--AMIIDÆ.
+
+_Skeleton entirely ossified; a single large gular plate; homocercal;
+fins without fulcra; a long soft dorsal fin. Abdominal and caudal parts
+of the vertebral column subequal in extent. Branchiostegals numerous._
+
+  [Illustration: Fig. 150.--Amia calva; _g_, gular plate.]
+
+   AMIA.--Body rather elongate, sub-cylindrical, compressed behind.
+   Snout short, cleft of the mouth of moderate width. Jaws with
+   an outer series of closely-set pointed teeth, and with a band
+   of rasp-like teeth; similar teeth on the vomer, palatine, and
+   pterygoid bones. Anal short; caudal fin rounded. Gills four;
+   air-bladder bifurcate in front, cellular, communicating with the
+   pharynx.
+
+The “Bow-fin” or “Mud-fish” (_A. calva_) is not uncommon in many
+of the fresh waters of the United States; it grows to a length of two
+feet. Little is known about its habits; small fish, crustaceans, and
+aquatic insects, have been found in its stomach. Wilder has observed
+its respiratory actions; it rises to the surface, and, without emitting
+any air-bubble whatever, opens the jaws widely, and apparently gulps in
+a large quantity of air; these acts of respiration are more frequently
+performed when the water is foul or has not been changed; and there
+is no doubt that an exchange of oxygen and carbonic acid is effected,
+as in the lungs of aërial vertebrates. The flesh of this fish is not
+esteemed.
+
+Fossil remains occur in tertiary deposits of North America, for
+instance in the Wyoming territory; they have been distinguished as
+_Protamia_ and _Hypamia_.
+
+
+                     SECOND SUB-CLASS--TELEOSTEI.
+
+_Heart with a non-contractile bulbus arteriosus; intestine without
+spiral valve; optic nerves decussating; skeleton ossified, with
+completely formed vertebræ; vertebral column diphycercal or homocercal;
+branchiæ free._[40]
+
+The Teleostei form the majority of the fishes of the present fauna, and
+are the geological successors of the Palæichthyes, undoubted Teleostei
+not ranging farther back than the Chalk. This sub-class comprises an
+infinite variety of forms; and as, naturally, many Ganoid fishes lived
+under similar external conditions, and led a similar mode of life as
+certain Teleostei, we find not a few analogous forms in both series:
+some Ganoids resembling externally the Teleosteous Siluroids, others
+the Clupeoids, others the Chætodonts, others the Scombresoces, etc.
+But there is no direct genetic relation between those fishes, as some
+Naturalists were inclined to believe.
+
+The Teleostei are divided into six orders:--
+
+   A. ACANTHOPTERYGII.--Part of the rays of the dorsal, anal, and
+   ventral fins not articulated, spines. The lower pharyngeals
+   separate. Air-bladder, if present, without pneumatic duct in the
+   adult.
+
+   B. ACANTHOPTERYGII PHARYNGOGNATHI.--Part of the rays of the
+   dorsal, anal, and ventral fins not articulated, spines. The
+   lower pharyngeals coalesced. Air-bladder without pneumatic duct.
+
+   C. ANACANTHINI.--Vertical and ventral fins without spinous rays.
+   Ventral fins, if present, jugular or thoracic. Air-bladder, if
+   present, without pneumatic duct. Lower pharyngeals separate.
+
+   D. PHYSOSTOMI.--All the fin rays articulated; only the first
+   of the dorsal and pectoral fins is sometimes ossified. Ventral
+   fins, if present, abdominal, without spine. Air-bladder, if
+   present, with a pneumatic duct.
+
+   E. LOPHOBRANCHII.--Gills not laminated, but composed of small
+   rounded lobes, attached to the branchial arches. Gill-cover
+   reduced to a large simple plate. A dermal skeleton replaces more
+   or less soft integuments.
+
+   F. PLECTOGNATHI.--A soft dorsal fin opposite to the anal;
+   sometimes elements of a spinous dorsal. Ventral fins none,
+   or reduced to spines. Gills pectinate; air-bladder without
+   pneumatic duct. Skin with rough scutes, or with spines, or naked.
+
+
+                     FIRST ORDER--ACANTHOPTERYGII.
+
+_Part of the rays of the dorsal, anal, and ventral fins are not
+articulated, more or less pungent spines. The lower pharyngeals are
+generally separate. Air-bladder, if present, without pneumatic duct in
+the adult._[41]
+
+
+             FIRST DIVISION--ACANTHOPTERYGII PERCIFORMES.
+
+_Body more or less compressed, elevated or oblong, but not elongate;
+the vent is remote from the extremity of the tail, behind the ventral
+fins if they are present. No prominent anal papilla. No superbranchial
+organ. Dorsal fin or fins occupying the greater portion of the
+back; spinous dorsal well developed, generally with stiff spines, of
+moderate extent, rather longer than, or as long as, the soft; the soft
+anal similar to the soft dorsal, of moderate extent or rather short.
+Ventrals thoracic, with one spine and with four or five rays._
+
+
+                        FIRST FAMILY--PERCIDÆ.
+
+_The scales extend but rarely over the vertical fins, and the lateral
+line is generally present, continuous from the head to the caudal fin.
+All the teeth simple and conical; no barbels. No bony stay for the
+præoperculum._
+
+A large family, represented by numerous genera and species in fresh
+waters, and on all the coasts of the temperate and tropical regions.
+Carnivorous.
+
+Fossil Percoids abound in some formations, for instance, at Monte
+Bolca, where species of _Labrax_, _Lates_, _Smerdis_ and _Cyclopoma_
+(both extinct), _Dules_, _Serranus_, _Apogon_, _Therapon_, and
+_Pristipoma_ have been recognised. _Paraperca_ is a genus recently
+discovered in the Marles of Aix-en-Provence. A species of _Perca_ is
+known from the freshwater deposit of Oeningen.
+
+   PERCA.--All the teeth are villiform, without canines; teeth
+   on the palatine bones and vomer; tongue toothless. Two dorsal
+   fins, the first with thirteen or fourteen spines; anal fin with
+   two spines. Præoperculum and præorbital serrated. Scales small;
+   head naked above. Branchiostegals seven. Vertebræ more than
+   twenty-four.
+
+The “Freshwater Perch” (_Perca fluviatilis_) is too familiarly known
+to require description. It is generally distributed over Europe and
+Northern Asia; and equally common in North America, there being no
+sufficient ground for separating specifically the specimens of the
+Western Hemisphere. It frequents especially still waters, and sometimes
+descends into brackish water. Its weight does not seem to exceed 5
+lbs. The female deposits her ova, united together by a viscid matter,
+in lengthened or net-shaped bands, on waterplants. The number of
+the eggs of one spawn may exceed a million. Two other species, _P.
+gracilis_, from Canada, and _P. schrenckii_, from Turkestan, have been
+distinguished, but they are very imperfectly known. An allied genus is
+_Siniperca_, from Northern China.
+
+  [Illustration: Fig. 151.--Perca fluviatilis, the Perch.]
+
+   PERCICHTHYS.--Differing from _Perca_ especially in the number of
+   the fin-spines, which are nine or ten in the first dorsal, and
+   three in the anal fin. The upper surface of the head scaly.
+
+These fishes represent the Freshwater Perches of the Northern
+Hemisphere in the fresh waters of the temperate parts of South America.
+Two species have been described from Patagonia, and one or two from
+Chili and Peru.
+
+   LABRAX.--All the teeth are villiform, without canines;
+   teeth on the palatine bones, vomer, and the tongue. Two dorsal
+   fins, the first with nine spines; anal fin generally with three.
+   Præoperculum serrated, and with denticulations along its lower
+   limb; præorbital with the margin entire. Scales rather small.
+   Branchiostegals seven; well developed pseudobranchiæ.
+
+The “Bass” are fishes common on the coasts of Europe and the Atlantic
+coasts, and in the fresh waters of the United States and Canada. The
+three European species are almost exclusively inhabitants of the sea,
+entering brackish, but never fresh waters, whilst the American species,
+the number of which is still uncertain, seem to affect principally
+fresh water, although some are also found in the sea. The best known
+European species is _Labrax lupus_ (see p. 41, Fig. 4), common on
+the British coasts. It is a voracious fish, with a remarkably large
+stomach, and received from the ancient Romans the appropriate name of
+_lupus_. By the Greeks it was so highly esteemed that Archestratus
+termed this or one of the two other closely-allied species, taken near
+Milet, “offspring of the gods.” They attributed to it a tender regard
+for its own safety; and Aristotle says that it is the most cunning of
+fishes; and that, when surrounded by the net, it digs for itself a
+channel of escape through the sand. Specimens of from two to three feet
+are not scarce, but its flesh is nowadays much less esteemed than in
+ancient times. Of the North American species _Labrax lineatus_ and
+_Labrax rufus_ are the most common.
+
+   LATES.--All the teeth are villiform, without canines; teeth on
+   the palatine bones and vomer, but none on the tongue. Two dorsal
+   fins--the first with seven or eight, the anal fin with two or
+   three, spines. Præoperculum with strong spines at the angle and
+   the lower limb; also the præorbital is strongly serrated. Scales
+   of moderate size. Branchiostegals seven; pseudobranchiæ present.
+
+Three well-known species belong to this genus. The Perch of the Nile
+and other rivers of tropical Africa (_Lates niloticus_); the Perch of
+the Ganges and other East Indian rivers, which enters freely brackish
+water, and extends to the rivers of Queensland (_Lates calcarifer_).
+These two species attain to a large size, the Indian species to a
+length of five feet. Hamilton says that “the vulgar English in Calcutta
+call it ‘Cockup,’ and that it is one of the lightest and most esteemed
+foods brought to table in that city.” Specimens two feet in length and
+caught in salt water are by far the best quality. The third species
+(_Lates colonorum_) is found in Australia only, and does not appear to
+grow to the same large size as its congeners.
+
+Allied to _Lates_ is _Psammoperca_ from Australia.
+
+   PERCALABRAX.--All the teeth villiform, without canines; teeth on
+   the palatine bones and vomer, but none on the tongue. Two dorsal
+   fins--the first with eleven, the anal fin with three spines.
+   Præoperculum serrated along its hinder margin, and with strong
+   spinous teeth below; præorbital not serrated. Scales rather
+   small. Branchiostegals seven; pseudobranchiæ present.
+
+This Perch (_Percalabrax japonicus_) is one of the most common fishes
+on the coasts of China, Japan, and Formosa; the Japanese name it
+“Zuzuki,” or “Seengo.”
+
+   ACERINA.--All the teeth villiform, without canines; teeth on
+   the vomer, but none on the palatine bones or the tongue. One
+   continuous dorsal fin, of which the spinous portion consists of
+   from thirteen to nineteen spines; two anal spines. Body rather
+   low, with rather small scales. Bones of the skull with wide
+   muciferous cavities; præoperculum denticulated.
+
+Small freshwater perches, of which _A. cernua_, named “Pope” in
+England, is the most common, and has the widest distribution in Central
+Europe and Siberia. The two other species have a more restricted range,
+_A. schrætzer_ being confined to the Danube and other rivers
+emptying into the Black Sea; and _A. czekanowskii_ to Siberian
+rivers. This genus is not represented in the Western Hemisphere.
+
+   LUCIOPERCA.--Teeth in villiform bands, those in the jaws with
+   additional canines; palatine bones toothed. Two dorsal fins--the
+   first with from twelve to fourteen, the anal fin with two
+   spines. Præoperculum serrated; scales small.
+
+The “Pike-Perches” are inhabitants of many lakes and rivers of the
+temperate northern zone. The European species is confined to the
+eastern two-thirds of the continent, and one of the most esteemed
+freshwater fishes; it attains to a length of three or four feet,
+and to a weight of from 25 to 30 lbs. It has been recommended for
+acclimatisation in England, and there is no doubt that in certain
+localities it might prove a valuable addition to the native fauna; but
+like all its congeners it is very voracious and destructive to smaller
+fishes. Two other species inhabit rivers of European and Asiatic
+Russia, and two or three the fresh waters of North America.
+
+   PILEOMA.--All the teeth minute, villiform, without canines;
+   teeth on the vomer and palatine bones. Two dorsal fins--the
+   first with fourteen or fifteen spines. Body rather elongate,
+   with small scales. Præoperculum not serrated.
+
+Small freshwater perches abundant in the United States. Like the
+following genus, and some others which need not be mentioned here,
+they can be regarded as small, dwarfed representatives of the
+preceding genera. The species seem to be numerous, but have not yet
+been sufficiently well distinguished. The latest and best account of
+them is by L. Vaillant, “Recherches sur les Poissons d’eaux douces de
+l’Amérique septentrionale (_Etheostomatidæ_),” in Nouv. Archiv. du
+Muséum d’Hist. Nat. de Paris, ix., 1873.
+
+   BOLEOSOMA.--Allied to _Pileoma_, but with only nine or ten
+   feeble spines in the first dorsal fin. North America.
+
+   ASPRO.--Body elongate, cylindrical; snout thick, projecting
+   beyond the mouth, which is situated at its lower side. All
+   the teeth villiform, without canines; teeth on the vomer and
+   palatine bones. Two separate dorsals. Præoperculum serrated;
+   præorbital entire. Scales small.
+
+Two small Perches from the Danube and some other rivers of the
+continent of Europe, _Aspro vulgaris_ and _A. zingel_.
+
+   CENTROPOMUS.--Body oblong, compressed, with scales of
+   moderate size. All the teeth villiform, without canines; teeth
+   on the vomer and palatine bones. Two dorsal fins, the first with
+   eight strong spines, the anal with three, the second of which is
+   very strong and long. Præoperculum with a double denticulated
+   edge.
+
+Numerous species are known from the West Indies and Central America.
+These fishes are found in fresh, brackish, and salt water, and some of
+the species indiscriminately enter all three kinds of water. They do
+not grow to any large size, but are esteemed as food.
+
+   ENOPLOSUS.--Body much elevated, the depth being still more
+   increased by the high vertical fins. All the teeth are
+   villiform, without canines; teeth on the vomer, palatine bones,
+   and the tongue. Two dorsal fins, the first with seven spines.
+   Præoperculum serrated, with spinous teeth at the angle. Scales
+   of moderate size.
+
+A small and very common marine species (_E. armatus_) on the coast
+of Australia, especially New South Wales. It is readily recognised by
+the peculiar shape of its body, and eight black transverse bands on a
+whitish ground.
+
+       *       *       *       *       *
+
+This, and the preceding genus, leads to the true “Sea perches,” which
+never, or but rarely, enter fresh water:--
+
+   CENTROPRISTIS.--Body oblong, with scales of small or moderate
+   size. Teeth villiform, with small canines in both jaws; vomerine
+   teeth placed in an angular band, or a short triangular patch;
+   teeth on the palatine bones, but none on the tongue. One dorsal,
+   with the formula 10/12 or less; anal fin 3/7(6). Præoperculum
+   serrated; sometimes with the angle projecting, and armed with
+   long spines.
+
+About twenty species of small size are known from temperate and
+tropical seas.
+
+ANTHIAS.--Body rather short, compressed, with scales of moderate
+size. Teeth villiform, with small canines in both jaws; teeth on the
+vomer, and palatine teeth. One dorsal, generally with ten spines; anal
+fin with three; caudal forked. The rays of one or more fins may be
+prolonged. Præoperculum serrated.
+
+About twenty species are known from temperate and tropical seas; they
+are mostly of small size, and agreeably coloured, pink and yellow
+being the predominant colours. _Anthias sacer_ is common in the
+Mediterranean, and was well known to the ancients. Aristotle says that
+the fishers of Sponges call it sacred, because no voracious fishes came
+to the places which it frequented, and the diver might descend with
+safety.--_Callanthias_ is a genus closely allied to _Anthias_.
+
+   SERRANUS.--Body oblong, compressed, with small scales. Teeth
+   villiform, with very distinct canines in both jaws; teeth on the
+   vomer and palatine bones, none on the tongue. One dorsal, mostly
+   with nine or eleven, rarely with eight, ten or twelve spines;
+   anal fin with three: all the spines being stout. Præoperculum
+   serrated behind and at the angle, but not below.
+
+  [Illustration: Fig. 152.--Serranus altivelis.]
+
+The “Sea perches proper” are found on the shores of all temperate and
+tropical seas, most abundantly in the latter. A few species enter
+brackish and even fresh water, one having been found as high up the
+Ganges as the confines of Nepal. However, all spawn in the sea. The
+variety of species is almost infinite, about 150 being tolerably
+well known, and many more having been described. The distinction of
+the species is most difficult, and nearly impossible to those who
+have no opportunity of closely and long observing them in nature,
+as they are not only subject to great variation of colour, but also
+to considerable changes dependent on age. Many are most agreeably
+coloured, and ornamented with spots, or cross bands or longitudinal
+stripes; colours which become more uniform with age in those species
+which attain to a large size. The majority remain of rather small
+size, growing to a length of one or two feet; but not a few reach
+more than twice that length, and may even become dangerous to man.
+Instances of bathers having been attacked by a gigantic species not
+uncommon at the Seychelles and Aden are on record, the persons having
+died from the injuries received. Almost all the species are eatable,
+and many are esteemed as food. One species is common on the British
+coasts (_S. cabrilla_), and probably some of the more southern species
+(_S. scriba_ and _S. gigas_) occasionally wander as far northwards as
+the British Channel. The species figured, _S. altvelis_, is locally
+distributed over nearly all the tropical parts of the Indian Ocean, and
+distinguished by particularly high dorsal and anal fins. _Anyperodon_
+and _Prionodes_ are two genera closely allied to _Serranus_.
+
+   PLECTROPOMA.--Form of the body and dentition (see p. 127, Fig.
+   54) similar to that of _Serranus_, with a præoperculum serrated
+   behind, and armed with spinous teeth below, which are directed
+   forwards. Dorsal fin with from seven to thirteen spines.
+
+About thirty species from tropical seas are known. _Trachypoma_ is
+allied to this genus.
+
+   POLYPRION.--Body oblong, rather compressed, covered with small
+   scales. All the teeth are villiform; teeth on the vomer,
+   palatine bones, and the tongue. One dorsal with eleven or twelve
+   spines; anal with three. Præoperculum denticulated; a strong,
+   rough, longitudinal ridge on the operculum.
+
+Two species are known: one from the European coasts (_P. cernium_),
+and one from Juan Fernandez (_P. kneri_). They attain to a weight of
+80 lbs. and more. The European species has the habit of accompanying
+floating wood, to which they are attracted by the small marine species
+generally surrounding such objects, and affording a supply of food. It
+is known by the name of “Stone-bass,” and excellent eating.
+
+   GRAMMISTES.--Body rather short, compressed, covered with minute
+   scales imbedded in the thick skin. All the teeth are villiform;
+   teeth on the vomer and palatine bones. Two dorsal fins, the
+   first with seven spines. Præoperculum without serrature, but
+   with three short spines. A short skinny barbel is frequently
+   developed at the chin.
+
+Three species are known from the Indo-Pacific; they are of small
+size. One, _G. orientalis_, is black, with six or seven white
+longitudinal stripes, and one of the most common coast-fishes of that
+ocean.
+
+   RHYPTICUS.--Body oblong, compressed, covered with minute scales
+   imbedded in the thick skin. All the teeth are villiform; teeth
+   on the vomer and palatine bones. The spines of the vertical fins
+   are but little developed, always in small number and short, and
+   may disappear entirely. Præoperculum not serrated, with some
+   obtuse spines.
+
+Four species are known: three from the West Indies and one from the
+Galapagoes Islands.
+
+Other genera allied to the two preceding are _Aulacocephalus_ from
+Mauritius, Reunion, and Japan; and _Myriodon_ from the coasts of
+Australia.
+
+   DIPLOPRION.--Body rather elevated, compressed, with small
+   scales. All the teeth villiform; teeth on the vomer and palatine
+   bones. Two dorsal fins, the first with eight spines; anal with
+   two. Præoperculum with a double denticulated limb.
+
+  [Illustration: Fig. 153.--Mesoprion monostigma.]
+
+The single species known (_D. bifasciatum_), is very common in the East
+Indian Archipelago, and on the coasts of Southern China and Japan. It
+is of small size, and ornamented with two broad black cross-bands.
+
+   MESOPRION.--Body oblong, compressed, covered with scales of
+   moderate size. Teeth villiform, with canines in both jaws;
+   teeth on the vomer and palatine bones. One dorsal fin, with
+   ten or eleven, rarely with more spines; anal fin with three.
+   Præoperculum serrated; in some species (_Genyoroge_) a more or
+   less distinct spinous knob projects from the surface of the
+   interoperculum, and is received in a more or less deep notch of
+   the præopercular margin.
+
+  [Illustration: Fig. 154.--Opercles _a_, of _Mesoprion_;
+  _b_, of _Genyoroge_; _o_, knob received in a notch
+  of the præoperculum.]
+
+About seventy species are known from tropical seas in both hemispheres,
+but it is noteworthy that the species with the peculiar protuberance
+of the interoperculum are confined to the Indo-Pacific. The coloration
+is much more simple than in the small-scaled Serrani, a uniform hue
+of greenish, pink, or red prevailing; species with longitudinal bands
+are scarce, but not rarely dark cross-bands or a large spot on the
+side occur. The majority of the species remain within very moderate
+dimensions, specimens exceeding three feet in length being scarce. They
+are generally eaten, and some of the species belong to the commonest
+fishes of the tropics, as _M. bengalensis_, _chrysurus_, _gembra_,
+_griseus_, and others.
+
+_Glaucosoma_ from Japan and Australia is allied to _Mesoprion_.
+
+   DULES.--Body oblong, compressed, with scales of moderate size,
+   and very indistinctly ctenoid. All the teeth are villiform;
+   teeth on the vomer and palatine bones. One dorsal with ten
+   spines; anal fin with three. Præoperculum serrated. Six
+   branchiostegals only.
+
+About ten species are known, inhabiting fresh waters of the coasts of
+the Indo-Pacific, and being especially common in the islands of this
+region, and also in Tropical Australia. Some live also in brackish
+water. Though of small size they are esteemed as food.
+
+   THERAPON.--Body oblong, compressed, with scales of moderate
+   size. All the teeth are villiform, those of the vomer and
+   palatine bones being rudimentary, and frequently absent. One
+   dorsal, with a depression in its upper margin, and twelve or
+   thirteen spines; anal fin with three. Præoperculum serrated.
+   Air-bladder with two divisions, an anterior and posterior. Six
+   branchiostegals.
+
+About twenty species are known, the distribution of which nearly
+coincides with _Dules_, but as some of the species are more or less
+marine, the genus is spread over the whole area of the tropical
+Indo-Pacific. Other species, especially those of Australian rivers,
+are entirely limited to fresh water. _Th. theraps_, _Th. servus_, and
+_Th. cuvieri_ belong to the most common fishes of that area, extending
+from the east coast of Africa to Polynesia. They are readily recognised
+by the blackish longitudinal bands with which the body is ornamented.
+All the species are of small size. _Helotes_ is closely allied to this
+genus.
+
+   PRISTIPOMA.--Body oblong, compressed, with ctenoid scales of
+   moderate size. Cleft of the mouth horizontal, not very wide,
+   with the jaws nearly equal in length anteriorly; a central pit
+   below the chin; villiform teeth in the jaws without canines;
+   palate toothless. One dorsal, with eleven to fourteen spines;
+   anal with three. Vertical fins not scaly, or with scales along
+   the base only. Præoperculum serrated. Branchiostegals, seven.
+
+  [Illustration: Fig. 155.--Lower view of mandible of Pristipoma
+  manadense.]
+
+About forty species are known, all from the sea. They are extremely
+common between the tropics, some of the species extending into the
+neighbouring sub-tropical parts. They do not attain a large size, and
+generally have a plain coloration. _Conodon_ is an allied genus.
+
+  [Illustration: Fig. 156.--Hæmulon brevirostrum.]
+
+   HÆMULON.--Body oblong, compressed, with ctenoid scales of
+   moderate size. Cleft of the mouth horizontal, generally wide,
+   with the jaws equal in length anteriorly; a central pit below
+   the chin; villiform teeth in the jaws, without canines; palate
+   toothless. One dorsal, with twelve or thirteen spines; anal with
+   three; the soft portions of the vertical fins scaly to their
+   margins. Præoperculum serrated. Branchiostegals, seven.
+
+Marine; sixteen species are known from the coasts of Tropical America;
+they are of rather small size. The species figured occurs on both sides
+of Central America. _Hapalogenys_ is an allied genus.
+
+   DIAGRAMMA.--Body oblong, compressed, covered with rather small
+   ctenoid scales. Upper profile of the head parabolic; cleft of
+   the mouth small, horizontal; from four to six pores under the
+   mandible, but without central pit. Teeth villiform, without
+   canines; palate toothless. One dorsal fin, with from nine to
+   fourteen spines; anal with three. Vertical fins not scaly.
+   Præoperculum serrated; infraorbital not armed. Branchiostegals,
+   six or seven.
+
+  [Illustration: Fig. 157.--Diagramma orientale, from the
+  Indo-Pacific.]
+
+Forty species are known, which, with very few exceptions, belong to
+the tropical parts of the Indo-Pacific. Some attain to a size not very
+common among Sea-Perches, viz. to a length of from three to four feet.
+Many are agreeably coloured with black bands or spots. All appear to be
+esteemed as food. _Hyperoglyphe_ from Australia is allied to this
+genus.
+
+   LOBOTES.--Body rather elevated, compressed, with ctenoid scales
+   of moderate size. Eye rather small. Snout obtuse, with oblique
+   cleft of the mouth, and with the lower jaw longest. Teeth
+   villiform, without canines; palate toothless. One dorsal fin
+   with twelve spines; anal with three. Præoperculum denticulated.
+   Branchiostegals, six.
+
+A remarkable fish (_L. auctorum_) on account of its extraordinary
+range. Common in many localities, scarcer in others, it occurs in the
+East Indies, and on all the Atlantic coasts of tropical and temperate
+America. Döderlein found it on the coast of Sicily in 1875. It lives in
+salt and brackish water, and is known to attain to a length of two feet.
+
+   HISTIOPTERUS.--Body rather elevated, strongly compressed, with
+   very small scales. Snout much produced, the anterior profile of
+   the head being concave. Mouth small, at the end of the snout.
+   Teeth villiform, without canines; palate toothless. Some of the
+   spines and rays of the vertical and pectoral fins very long. One
+   dorsal, with about ten spines; anal with three. Præopercular
+   margin partly serrated. Branchiostegals, six.
+
+Marine. Four species are known from Japan and South Australia. The
+species figured attains to a length of 20 inches, and is esteemed as
+food. It is known at Melbourne by the names of “Boar Fish” or “Bastard
+Dorey.”
+
+  [Illustration: Fig. 158.--Histiopterus recurvirostris.]
+
+   GERRES.--Body oblong, or rather elevated, covered with scales
+   of moderate size, which are either entirely smooth or minutely
+   ciliated. Mouth very protractile, and descending when thrust
+   out. Eye rather large. No canine teeth; dentition feeble, and
+   palate toothless. The two divisions of the dorsal fin are nearly
+   separated by a deep incision. Formula of the vertical fins--D.
+   9/10 A. 2·3/7·9. Caudal fin forked. Præoperculum generally
+   without denticulation. Lower pharyngeal bones coalescent.
+
+  [Illustration: Fig. 159.--Gerres altispinis, from the mouth of
+  the Ganges.]
+
+More than thirty species are known of this genus, which bear so close a
+resemblance to one another that their distinction is rather difficult.
+They live in the seas between the Tropics, and some, perhaps all, of
+the species enter fresh water. Very rarely they exceed a length of ten
+inches; nearly all have a plain silvery coloration. The coalescence
+of their lower pharyngeals renders their systematic position rather
+uncertain, and, indeed, some Ichthyologists have referred them to the
+Pharyngognaths.
+
+   SCOLOPSIS.--Body oblong, covered with scales finely serrated
+   and of moderate size. Jaws nearly equal in length anteriorly;
+   cleft of the mouth horizontal. Teeth villiform, without canines;
+   palate toothless. One dorsal fin. Formula of the vertical fins:
+   D. 10/9 A. 3/7. Caudal fin forked. Præoperculum distinctly
+   denticulated; infraorbital ring with a spine directed backwards.
+   Branchiostegals, five.
+
+  [Illustration: Fig. 160.--Infraorbital spine of Scolopsis
+  monogramma.]
+
+Marine, and of small size. Twenty-five species are known from the
+tropical parts of the Indo-Pacific. _Heterognathodon_ is an allied
+genus, but without the infraorbital spine.
+
+   DENTEX.--Body oblong, covered with ctenoid scales of
+   moderate size. Cleft of the mouth nearly horizontal, with the
+   jaws equal in length anteriorly. Canine teeth in both jaws;
+   palate toothless. One dorsal fin. Formula of the vertical fins:
+   D. 10·13/10·12 A. 3/8·9. Caudal fin forked. Præoperculum without
+   serrature; præorbital unarmed and broad, there being a wide
+   space between the eye and the cleft of the mouth. Cheek covered
+   by more than three series of scales. Branchiostegals, six.
+
+Marine Fishes, rather locally distributed in the Mediterranean, on the
+south coast of Africa, in the Red Sea, East Indian Archipelago, and
+on the coasts of China and Japan. About fourteen species are known,
+some of which attain a weight of 30 lbs. and more. They form a not
+unimportant article of food where they are found in any number, as on
+the Cape of Good Hope. The species found in the Mediterranean (_D.
+vulgaris_) wanders sometimes to the south coast of England, and is
+one of the larger species. The coloration of these fishes is rather
+uniform, silvery, or pink, or greenish. _Symphorus_ is an allied genus
+from the Indo-Pacific.
+
+   SYNAGRIS.--Body rather elongate, covered with ciliated
+   scales of moderate size. Cleft of the mouth horizontal, with
+   the jaws equal in length anteriorly. One continuous dorsal,
+   with feeble spines; dorsal 10/9, anal 3/7. Caudal deeply
+   forked. Teeth villiform, with canines at least in the upper
+   jaw. Infraorbital not armed; præoperculum without, or with a
+   very indistinct serrature. Cheek with three series of scales.
+   Branchiostegals six.
+
+Marine fishes of small size; about twenty species are known from the
+tropical parts of the Indo-Pacific. _Pentapus_, _Chætopterus_, and
+_Aphareus_ are allied genera from the same area.
+
+   MAENA.--Body oblong, compressed, covered with ciliated scales
+   of moderate size. Mouth very protractile, the intermaxillary
+   pedicles extending backwards to the occiput. Teeth villiform;
+   minute teeth on the vomer. One dorsal, scaleless, with feeble
+   spines. D. 11/11, A. 3/9. Caudal fin forked. Præoperculum
+   without serrature. Branchiostegals six.
+
+Small fishes from the Mediterranean, known to the ancients; valueless
+as food. Three species.
+
+   SMARIS.--Body oblong or cylindrical, covered with rather small
+   ciliated scales. Mouth very protractile, the intermaxillary
+   pedicles extending backwards to the occiput. Teeth villiform.
+   Palate toothless. One dorsal, scaleless, with eleven or more
+   very feeble spines; anal with three. Caudal fin forked.
+   Præoperculum without serrature. Branchiostegals six.
+
+Small fishes from the Mediterranean. Six species.
+
+   CÆSIO.--Body oblong, covered with ciliated scales of moderate
+   size. Cleft of the mouth more or less oblique, with the
+   jaws equal in length anteriorly, or with the lower somewhat
+   projecting. Teeth villiform; palate generally toothless. One
+   dorsal, with from nine to thirteen very feeble spines, with the
+   anterior part highest, and the posterior covered with minute
+   scales. Caudal fin deeply forked. Præoperculum without, or with
+   minute, serrature.
+
+Small fishes from the Indo-Pacific. Twelve species.
+
+   ERYTHRICHTHYS.--Body elongate, covered with small ciliated
+   scales. Mouth very protractile, the pedicles of the
+   intermaxillary extending to the occiput. Dentition quite
+   rudimentary or entirely absent Two dorsal fins connected by
+   a series of very feeble spines; also the anterior spines are
+   feeble. Præoperculum not serrated.
+
+  [Illustration: Fig. 161.--Erythrichthys nitidus.]
+
+  [Illustration: Fig. 162.--Enlarged scale.]
+
+  [Illustration: Fig. 163.--Protractile mouth.]
+
+Small fishes from various tropical and temperate seas. Four species:
+the species figured occurs, but is not common, on the coasts of
+Western Austria, Tasmania, and New Zealand.
+
+   OLIGORUS.--Body oblong, covered with small scales. Cleft of the
+   mouth rather oblique, the lower jaw being the longer. Teeth
+   villiform, without canines; teeth on the vomer and palatine
+   bones. One dorsal, with eleven spines; anal with three; caudal
+   fin rounded. Præoperculum with a single smooth or obtusely
+   denticulated margin.
+
+To this genus belong two fishes well known on account of the excellent
+flavour of their flesh. The first (_O. macquariensis_) is called
+by the colonists “Murray-Cod,” being plentiful in the Murray River
+and other rivers of South Australia. It attains to a length of more
+than three feet, and to a weight of nearly 100 lbs. The second (_O.
+gigas_) is found in the sea, on the coast of New Zealand, and called
+by the Maoris and colonists “Hapuku.” Its average weight is about 45
+lbs., but occasionally large specimens of more than a hundredweight
+are caught. At certain localities it is so plentiful that it may form
+an important article of trade. Dr. Hector, who has had opportunity of
+examining it in a fresh state, has pointed out anatomical differences
+from the Murray-Cod, from which it appears that it would be better
+placed in a distinct genus.
+
+  [Illustration: Fig. 164.--The Murray-Cod, _Oligorus
+  macquariensis_.]
+
+   GRYSTES.--Body oblong, covered with scales of moderate size. All
+   the teeth villiform, without canines; teeth on the vomer and
+   palatine bones. One dorsal fin with ten spines; anal with three;
+   caudal fin rounded. Præoperculum with a single smooth margin.
+
+One species, from the fresh waters of the United States (_G.
+salmonoides_), attains to a length of more than two feet. It is
+known by the name of “Growler,” and eaten.
+
+   ARRIPIS.--Body oblong, covered with scales of moderate size. All
+   the teeth villiform, without canines; teeth on the vomer and
+   palatine bones. One dorsal fin, with nine slender spines; anal
+   with three. Præoperculum denticulated.
+
+  [Illustration: Fig. 165.--_Arripis salar_, South Australia.]
+
+Three species are known, from the coasts of Southern Australia and New
+Zealand. They are named by the colonists Salmon or Trout, from their
+elegant form and lively habits, and from the sport they afford to the
+angler. Their usual size is from 1 to 3 lbs., but specimens of double
+that weight are taken. The smaller specimens are the more delicate and
+better flavoured. When not fresh, they are liable to assume poisonous
+properties; and cases of poisoning are not unfrequently caused by them.
+
+   HURO.--Body oblong, compressed, covered with scales of moderate
+   size. All the teeth villiform; bones of the head without
+   serrature. Mouth rather oblique, with the lower jaw projecting.
+   Two dorsal fins, the first with six spines.
+
+The “Black Bass” of Lake Huron (_Huro nigricans_).
+
+   AMBASSIS.--Body short, strongly compressed, covered with large
+   thin deciduous scales. Mouth oblique, with the lower jaw
+   longest; teeth villiform, without conspicuously larger canines;
+   teeth on the vomer and palatine bones. Two dorsal fins, the
+   first with seven, the anal with three spines; a horizontal
+   spine pointing forwards in front of the dorsal fin. The lower
+   limb of the præoperculum with a double serrated margin.
+
+This genus comprises the smallest of all Percoids, some of the species
+not much exceeding one inch in length. They are most abundant on the
+coasts of the tropical Indo-Pacific, and in the fresh waters belonging
+to that area. The species are numerous (some thirty having been
+described), and very difficult to distinguish. Their coloration is very
+plain, a silvery hue prevailing over the whole fish.
+
+   APOGON.--Body rather short, covered with large deciduous scales.
+   Mouth oblique, with the lower jaw longest; teeth villiform,
+   without canines; teeth on the vomer and palatine bones. Two
+   dorsal fins, the first with six or seven, the anal with two
+   spines. Præoperculum with a double edge on the margin, one or
+   both edges being serrated. Seven branchiostegals.
+
+  [Illustration: Fig. 166.--Apogon frenatus.]
+
+Although of similarly small size, the fishes of this genus represent a
+more highly developed form of the Percoid type than _Ambassis_. Their
+distribution coincides very much with that of _Ambassis_, but they
+are chiefly marine, comparatively few of the species entering fresh
+water. They belong to the kind of fishes which, from their habit,
+are termed “Coral Fishes,” being found in greatest abundance on, or
+in the neighbourhood of, coral reefs, in company with Chætodonts,
+Pomacentridæ, and others. Their colours also are ornamental and highly
+diversified, as is generally the case in coral fishes, the majority of
+the species showing transverse or longitudinal bands or large spots,
+and numerous other smaller markings which, in the dead fish, soon
+disappear. Nearly one hundred species have been described, of which
+a few only occur in the Atlantic, one extending northwards into the
+Mediterranean.
+
+_Chilodipterus_, _Acropoma_, and _Scombrops_ are allied genera, but
+with canine teeth in one or both jaws.
+
+   POMATOMUS.--Body oblong, covered with scales of moderate size.
+   Eye very large. All the teeth villiform, without canines; teeth
+   on the vomer and palatine bones. Two dorsal fins, the first with
+   seven, the anal with two spines. No serration on any of the
+   bones of the head. Branchiostegals seven.
+
+One species only is known, _P. telescopium_, which grows to a length
+of nearly two feet. It is not uncommon in the Mediterranean and
+neighbouring parts of the Atlantic, but only occasionally caught, as it
+lives habitually at a greater depth than any other Percoid as far as is
+known at present, probably at depths from 80 to 200 fathoms; a habit
+sufficiently indicated by its exceedingly large eye.
+
+PRIACANTHUS.--Body short, compressed, covered with small rough
+scales, which extend also over the short snout. Lower jaw and chin
+prominent. Eye large. All the teeth villiform, without canines; teeth
+on the vomer and palatine bones. One dorsal fin with ten spines, anal
+with three. Præoperculum serrated, with a more or less prominent, flat,
+triangular spine at the angle.
+
+A very natural genus, easily recognised, and without direct relation to
+the other Percoid genera. The species, of which seventeen are known,
+are spread over nearly all the tropical seas, and belong to the more
+common fishes. They scarcely exceed a length of twelve inches, and are
+very uniformly coloured, red, pink, and silvery prevailing.
+
+       *       *       *       *       *
+
+The following three genera form a group by themselves, which, however,
+is defined rather by its geographical limits and similarity of general
+appearance than by distinctive anatomical characters. The species are
+abundant in the fresh waters of the United States, and well known by
+the name of “Sun Fishes.” They rarely exceed a length of six inches,
+and are not used as food. The number of species is uncertain.
+
+   CENTRARCHUS.--Body short, compressed, with scales of moderate
+   size. All the teeth villiform, without canines; teeth on the
+   vomer, palatines, and on the tongue. One dorsal fin; anal
+   generally with more than three spines. Præoperculum without
+   serrature; operculum not lobed.
+
+   BRYTTUS.--Body short, compressed, with scales of moderate size.
+   All the teeth villiform, without canines; teeth on the vomer and
+   palatine bones. One dorsal fin with nine or ten, anal with three
+   spines. Præoperculum not serrated; operculum with a rounded
+   membranaceous coloured lobe behind.
+
+   POMOTIS.--Body short, compressed, with scales of moderate
+   length. All the teeth villiform, without canines; teeth on the
+   vomer, but none on the palatine bones. One dorsal, with from
+   nine to eleven spines, anal with three. Præoperculum entire
+   or minutely serrated; operculum with a rounded membranaceous
+   coloured lobe behind.
+
+       *       *       *       *       *
+
+A NORTH AMERICAN Freshwater genus, _Aphredoderus_, occupies a perfectly
+isolated position in the system, and is evidently the type of a
+distinct family. It resembles the “Sun-fishes” of the same country with
+regard to the structure of the vertical fins, but has the vent situated
+in front of the ventrals, which are composed of more than five soft
+rays. The body is oblong, compressed, covered with ctenoid scales. The
+dorsal fin is single, and has three spines in front. Infraorbital and
+præoperculum with spinous teeth. Villiform teeth in the jaws, on the
+vomer and palatine bones. _A. sayanus_ from the southern streams and
+fresh waters of the Atlantic States.
+
+To complete the list of Percoid genera, we have to mention the
+following:--_Siniperca_, _Etelis_, _Niphon_, _Aprion_, _Apsilus_,
+_Pentaceros_, _Velifer_, _Datnioides_, _Percilia_, _Lanioperca_.
+
+
+                     SECOND FAMILY--SQUAMIPINNES.
+
+_Body compressed and elevated, covered with scales, either finely
+ctenoid or smooth. Lateral line continuous, not continued over the
+caudal fin. Mouth in front of the snout, generally small, with lateral
+cleft. Eye lateral, of moderate size. Six or seven branchiostegals.
+Teeth villiform or setiform, in bands, without canines or incisors.
+Dorsal fin consisting of a spinous and soft portion of nearly equal
+development; anal with three or four spines, similarly developed as
+the soft dorsal, both being many-rayed. The vertical fins more or less
+densely covered with small scales. The lower rays of the pectoral fin
+branched, not enlarged; ventrals thoracic, with one spine and five soft
+rays. Stomach coecal._
+
+The typical forms of this family are readily recognised by the form
+of their body, and by a peculiarity from which they derive their
+name _Squamipinnes_; the soft, and frequently also the spinous part
+of their dorsal and anal fins are so thickly covered with scales
+that the boundary between fins and body is entirely obliterated. The
+majority are inhabitants of the tropical seas, and abound chiefly
+in the neighbourhood of coral-reefs. The beauty and singularity of
+distribution of the colours of some of the genera, as _Chætodon_,
+_Heniochus_, _Holacanthus_, is scarcely surpassed by any other group
+of fishes. They remain within small dimensions, and comparatively few
+are used as food. They are carnivorous, feeding on small invertebrates.
+Only a few species enter brackish water.
+
+Extinct representatives of this family are not scarce at Monte Bolca
+and in other tertiary formations. All, at least those admitting of
+definite determination, belong to existing genera, viz. _Holacanthus_,
+_Pomacanthus_, _Ephippium_, _Scatophagus_. Very singular is the
+occurrence of _Toxotes_ in the Monte Bolca strata.
+
+The following genera have no teeth on the palate:--
+
+   CHÆTODON.--One dorsal fin, without any notch in its upper
+   margin, and with the soft and spinous portions similarly
+   developed; none of the spines elongate. Snout short or of
+   moderate length. Præoperculum without, or with a fine,
+   serration, and without spine at the angle. Scales generally
+   large or of moderate size.
+
+  [Illustration: Fig. 167.--Chætodon ephippium.]
+
+Seventy species are known from the tropical parts of the Atlantic and
+Indo-Pacific, nearly all being beautifully ornamented with bands or
+spots. Of the ornamental markings a dark or bicoloured band, passing
+through the eye and ascending towards the back, is very generally
+found in these fishes; it frequently occurs again in other marine
+Acanthopterygians, in which it is not rarely a sign of the immature
+condition of the individual. The Chætodonts are most numerous in the
+neighbourhood of the coral-reefs of the Indo-Pacific, the species
+figured (_C. ephippium_) being as common in the East Indian
+Archipelago as in Polynesia, like many others of its congeners.
+
+   CHELMO differs from _Chætodon_ only in having the snout produced
+   into a more or less long tube.
+
+  [Illustration: Fig. 168.--Chelmo marginalis, from the coast of
+  Australia.]
+
+Only four species are known, locally distributed in the tropical seas.
+_Ch. rostratus_, the oldest species known, is said to have the instinct
+of throwing a drop of water from its bill so as to light upon any
+insect resting on a leaf, and thus make it fall, that it may instantly
+dart upon it. This statement is erroneous, and probably rests upon
+the mistaken notion that the long bill is especially adapted for this
+manœuvre, which, indeed, is practised by another fish of this family
+(_Toxotes_). The long slender bill of Chelmo (which is a true saltwater
+fish) rather enables it to draw from holes and crevices animals which
+otherwise could not be reached by it.
+
+   HENIOCHUS.--One dorsal, with from eleven to thirteen spines, the
+   fourth of which is more or less elongate and filiform. Snout
+   rather short or of moderate length. Præoperculum without spine.
+   Scales of moderate size.
+
+Four species are known from the tropical Indo-Pacific. _H.
+macrolepidotus_ is one of the most common fishes of that area; the
+species figured (_H. varius_) retains in a conspicuous manner
+horn-like protuberances on bones of the head, with which the young of
+all the species of this genus seem to be armed.
+
+  [Illustration: Fig. 169.--Heniochus varius.]
+
+   HOLACANTHUS.--Præoperculum with a strong spine at the angle. One
+   dorsal, with from twelve to fifteen spines. Scales of moderate
+   or small size.
+
+Forty species are known, which, in their geographical distribution
+accompany, and are quite analogous to, the Chætodonts. One of the most
+common and most beautiful is called “Emperor of Japan” by the Dutch,
+which name has been adopted by Bloch for its specific designation,
+_Holacanthus imperator_. Its body is blue, longitudinally traversed
+by about thirty yellow bands; the ocular band, and the side behind the
+head, are black, edged with yellow; the caudal fin is yellow. It is a
+large species of this genus, sometimes attaining a length of 15 inches,
+and as an article of food is one of the most esteemed of all the Indian
+species. With regard to beauty of colours it is surpassed by another
+allied species, _H. diacanthus_, which likewise ranges from the east
+coast of Africa to Polynesia.
+
+   POMACANTHUS differs from _Holacanthus_ in having from eight to
+   ten spines only in the dorsal fin.
+
+The single species (_P. paru_) on which this genus is founded is
+one of the most common fishes of the West Indies, and offers one of
+the most remarkable instances of variation of colour within the limits
+of the same species: some specimens being ornamented with more or less
+distinct yellowish cross-bands, others with yellow crescent-shaped
+spots; in others black spots predominate.
+
+  [Illustration: Fig. 170.--Scatophagus multifasciatus.]
+
+   SCATOPHAGUS.--Two dorsal fins, united at the base, the first
+   with ten or eleven spines; only the second is scaly. A recumbent
+   spine before the dorsal, pointing forwards. Anal with four
+   spines. Snout rather short. Præoperculum without spine. Scales
+   very small.
+
+Four species are known, from the Indian Ocean, of which _S. argus_
+is the most generally known, in fact, one of the most common Indian
+shore-fishes. It freely enters large rivers, and is said not to be
+particular in the selection of its food. The species figured (_S.
+multifasciatus_) represents _S. argus_ on the coasts of Australia.
+
+  [Illustration: Fig. 171.--Bony enlargement of cranial bones of
+  Ephippus. _a_, Enlargement of the frontal, and _b_,
+  of the supraoccipital bones; _c_, interorbital septum;
+  _d_, basis cranii. ⅓ nat. size.]
+
+   EPHIPPUS.--Snout short, with the upper profile parabolic. Dorsal
+   fin deeply emarginate between the spinous and soft portions,
+   the former with nine spines, the third of which is rather
+   elongate, and flexible; spinous portion not scaly; anal spines
+   three. Pectoral fin short. Præoperculum without spine. Scales of
+   moderate size, or rather small.
+
+Two or three species are known from the warmer parts of the Atlantic
+and Indian Oceans. The Atlantic species (_E. faber_) shows the
+remarkable peculiarity that in old specimens (12 and more inches long)
+the occipital crest, and sometimes some of the anterior neural and
+hæmal spines are enormously enlarged into a globular bony mass. This
+can hardly be regarded as a pathological change of the bone, as it has
+been found in all old specimens, without exception.
+
+_Drepane_ is allied to _Ephippus_, but has very long falciform pectoral
+fins. The single species _D. punctata_ is common in the Indian Ocean
+and on the coasts of Australia. _Hypsinotus_, from Japan, appears to
+inhabit a greater depth than the other Squamipinnes.
+
+_Scorpis_ and _Atypichthys_ are genera distinguished from the
+preceding by the presence of vomerine teeth. They belong to the
+coast-fauna of Australia, New Zealand, and Chili.
+
+   TOXOTES.--Body short, compressed, covered with scales of
+   moderate size. Snout pointed, with a wide lateral mouth and
+   projecting lower jaw. One dorsal, with five strong spines
+   situated on the posterior part of the back; the soft portion
+   and the anal fin scaly, the latter with three spines. Villiform
+   teeth in the jaws, on the vomer and palatine bones. Scales of
+   moderate size, cycloid.
+
+  [Illustration: Fig. 172.--Toxotes jaculator.]
+
+Two species are known from the East Indies, one (_T. jaculator_),
+which is the more common, ranging to the north coast of Australia. It
+has received its name from its habit of throwing a drop of water at an
+insect which it perceives close to the surface, in order to make it
+fall into it. The Malays, who call it “Ikan sumpit,” keep it in a bowl,
+in order to witness this singular habit, which it continues even in
+captivity.
+
+
+                        THIRD FAMILY--MULLIDÆ.
+
+_Body rather low and slightly compressed, covered with large thin
+scales, without or with an extremely fine serrature. Two long erectile
+barbels are suspended from the hyoid, and are received between the rami
+of the lower jaw and opercles. Lateral line continuous. Mouth in front
+of the snout, with the cleft lateral and rather short; teeth very
+feeble. Eye lateral, of moderate size. Two short dorsal fins remote
+from each other, the first with feeble spines; anal similar to the
+second dorsal. Ventrals with one spine and five rays. Pectorals short.
+Branchiostegals four; stomach siphonal._
+
+The “Red Mullets” form a very natural family, which, on account of
+slight modifications of the dentition, has been divided into several
+sub-genera--_Upeneoides_, _Upeneichthys_, _Mullus_, _Mulloides_, and
+_Upeneus_. They are marine fishes, but many species enter brackish
+water to feed on the animalcules abounding in the flora of brack-water.
+About forty different species are known chiefly from tropical seas,
+the European species (_M. barbatus_, see p. 43, Fig. 7), extending
+far northwards into the temperate zone. None attain to a large size,
+specimens of from two to three lbs. being not common, but all are
+highly esteemed as food.
+
+The most celebrated is the European species (of which there is one
+only, _M. surmuletus_ being probably the female). The ancient Romans
+called it _Mullus_, the Greeks τριγλη. The Romans priced it above any
+other fish; they sought for large specimens far and wide, and paid
+ruinous prices for them.
+
+              “Mullus tibi quatuor emptus
+    Librarum, cœnæ pompa caputque fuit,
+    Exclamare libet, non est hic improbe, non est
+    Piscis: homo est; hominem, Calliodore, voras.”
+                                     MARTIAL, x. 31.
+
+Then, as nowadays, it was considered essential for the enjoyment of
+this delicacy that the fish should exhibit the red colour of its
+integuments. The Romans brought it, for that purpose, living into the
+banqueting room, and allowed it to die in the hands of the guests, the
+red colour appearing in all its brilliancy during the death struggle of
+the fish. The fishermen of our times attain the same object by scaling
+the fish immediately after its capture, thus causing a permanent
+contraction of the chromatophors containing the red pigment (see p.
+183).
+
+
+                        FOURTH FAMILY--SPARIDÆ.
+
+_Body compressed, oblong, covered with scales, the serrature of which
+is very minute, and sometimes altogether absent. Mouth in front of the
+snout, with the cleft lateral. Eye lateral, of moderate size. Either
+cutting teeth in front of the jaws, or molar teeth on the side; palate
+generally toothless. One dorsal fin, formed by a spinous and soft
+portion of nearly equal development. Anal fin with three spines. The
+lower rays of the pectoral fin are generally branched, but in one genus
+simple. Ventrals thoracic, with one spine and five rays._
+
+The “Sea-breams” are recognised chiefly by their dentition, which is
+more specialised than in the preceding families, and by which the
+groups, into which this family has been divided, are characterised.
+They are inhabitants of the shores of all the tropical and temperate
+seas. Their coloration is very plain. They do not attain to a large
+size, but the majority are used as food.
+
+The extinct forms found hitherto are rather numerous; the oldest come
+from the cretaceous formation of Mount Lebanon; some belong to living
+genera, as _Sargus_, _Pagellus_; of others from Eocene and Miocene
+formations no living representative is known--_Sparnodus_, _Sargodon_,
+_Capitodus_, _Soricidens_, _Asima_.
+
+_First Group--Cantharina._--More or less broad cutting, sometimes
+lobate, teeth in front of the jaws; no molars or vomerine teeth;
+the lower pectoral rays are branched. Partly herbivorous, partly
+carnivorous. The genera belonging to this group are:--_Cantharus_
+from the European and South African coasts, of which one species (_C.
+lineatus_), is common on the coasts of Great Britain, and locally known
+by the names “Old Wife,” “Black Sea-bream;” _Box_, _Scatharus_, and
+_Oblata_ from the Mediterranean and neighbouring parts of the Atlantic;
+_Crenidens_ and _Tripterodon_ from the Indian Ocean; _Pachymetopon_,
+_Dipterodon_, and _Gymnocrotaphus_ from the Cape of Good Hope;
+_Girella_ and _Tephræops_ from Chinese, Japanese, and Australian Seas;
+_Doydixodon_ from the Galapagos Islands and the coasts of Peru.
+
+  [Illustration: Fig. 173.--Tephræops richardsonii, from King
+  George’s Sound.]
+
+_Second Group--Haplodactylina._--In both jaws flat and generally
+tricuspid teeth; no molars; vomerine teeth. The lower pectoral rays
+simple, not branched. Vegetable feeders. Only one genus is known,
+_Haplodactylus_, from the temperate zone of the Southern Pacific.
+
+_Third Group--Sargina._--Jaws with a single series of incisors
+in front, and with several series of rounded molars on the side. One
+genus is known, _Sargus_, which comprises twenty species; several
+of them occur in the Mediterranean and the neighbouring parts of the
+Atlantic, and are popularly called “Sargo,” “Sar,” “Saragu:” names
+derived from the word Sargus, by which name these fishes were well
+known to the ancient Greeks and Romans. One of the largest species is
+the “Sheep’s-head” (_Sargus ovis_), from the coasts of the United
+States, which attains to a weight of 15 lbs., and is highly esteemed on
+account of the excellency of its flesh. Singularly enough, this genus
+occurs also on the east coast of Africa, one of these East-African
+species being identical with _S. noct_ from the Mediterranean.
+These fishes evidently feed on hard-shelled animals, which they crush
+with their molar teeth.
+
+  [Illustration: Fig. 174.--The Sheep’s-head, _Sargus ovis_,
+  of North America.]
+
+  [Illustration: Fig. 175.--Scale of Lethrinus.]
+
+_Fourth Group--Pagrina._--Jaws with conical teeth in front and molar
+teeth on the sides. Feeding, as the preceding, on hard-shelled animals,
+like Mollusks and Crustaceans. This group is composed of several
+genera:--
+
+   LETHRINUS.--Cheeks scaleless. Body oblong, covered with scales
+   of moderate size (L. lat. 45–50). Canine teeth in front; lateral
+   teeth in a single series, broadly conical or molar-like. Formula
+   of the fins: D. 10/9, A. 3/8.
+
+More than twenty species are known, all of which, with one exception,
+occur in the tropical Indo-Pacific. The species, forming this
+exception, occurs, singularly enough, on the west coast of Africa,
+where more than one Indian genus reappears in isolated representative
+species. Some Lethrini attain to a length of three feet.
+
+_Sphærodon_ is closely allied to _Lethrinus_, but has scales on the
+cheek. One species from the Indo-Pacific.
+
+   PAGRUS.--Body oblong, compressed, with scales of moderate size.
+   Several pairs of strong canine-like teeth in both jaws; molars
+   arranged in two series. Cheeks scaly. The spines of the dorsal
+   fin, eleven or twelve in number, are sometimes elongate, and can
+   be received in a groove; anal spines three.
+
+Thirteen species are known, chiefly distributed in the warmer parts
+of the temperate zones, and more scantily represented between the
+tropics. Several species (_P. vulgaris, P. auriga, P. bocagii_) occur
+in the Mediterranean and the neighbouring parts of the Atlantic; one
+(_P. argyrops_) is well known on the coasts of the United States
+under the names of “Scup,” “Porgy,” or “Mishcup,” and one of the most
+important food fishes, growing to a length of 18 inches and a weight
+of 4 lbs.; another (_P. unicolor_) is one of the best-known sea-fishes
+of Southern Australia and New Zealand, where it is called “Snapper;”
+it is considered very good eating, like all the other species of this
+genus, and attains, like some of them, a length of more than 3 feet and
+a weight exceeding 20 lbs.
+
+   PAGELLUS.--Body oblong, compressed, with scales of moderate
+   size. Jaws without canines; molars on the sides arranged in
+   several series. Cheeks scaly. The spines of the dorsal fin, from
+   eleven to thirteen in number, can be received in a groove; anal
+   spines three.
+
+Seven species are known, the majority of which are European, as
+_P. erythrinus_, common in the Mediterranean, and not rare on the
+south coast of England, where it is generally termed “Becker;”
+_P. centrodontus_, the common “Sea-bream” of the English coasts,
+distinguished by a black spot on the origin of the lateral line; in the
+young, which are called “Chad” by Cornish and Devon fishermen, this
+spot is absent; _P. owenii_, the “Axillary or Spanish Sea-Bream,”
+likewise from the British coasts. _Pagellus lithognathus_, from the
+coasts of the Cape of Good Hope, attains to a length of four feet, and
+is one of the fishes which are dried for export and sale to whalers.
+
+   CHRYSOPHRYS.--Body oblong, compressed, with scales of moderate
+   size. Jaws with four or six canine teeth in front, and with
+   three or more series of rounded molars on each side. Cheeks
+   scaly. The spines of the dorsal fin, eleven or twelve in number,
+   can be received in a groove; anal spines three.
+
+Some twenty species are known from tropical seas and the warmer parts
+of the temperate zones. Generally known is _Ch. aurata_, from the
+Mediterranean, occasionally found on the south coast of England,
+where it is named “Gilthead.” The French call it “Daurade,” no doubt
+from the Latin _Aurata_, a term applied to it by ancient authors. The
+Greeks named it Chrysophrys (_i.e._ golden eyebrow), in allusion to
+the brilliant spot of gold which it bears between its eyes. According
+to Columella, the Aurata was among the number of the fishes brought
+up by the Romans in their vivaria; and the inventor of those vivaria,
+one Sergius Orata, is supposed to have derived his surname from
+this fish. It is said to grow extremely fat in artificial ponds.
+Duhamel states that it stirs up the sand with the tail, so as to
+discover the shell-fish concealed in it. It is extremely fond of
+mussels, and its near presence is sometimes ascertained by the noise
+which it makes while breaking their shells with its teeth. Several
+species found on the Cape of Good Hope attain to as large a size as
+_Pagellus lithognathus_, and are preserved for sale like that species.
+_Chrysophrys hasta_ is one of the most common species of the East
+Indian and Chinese coasts, and enters large rivers.
+
+_Fifth Group--Pimelepterina._--In both jaws a single anterior series
+of cutting teeth, implanted by a horizontal posterior process, behind
+which is a band of villiform teeth. Villiform teeth on the vomer,
+palatines and the tongue. Vertical fins densely covered with minute
+scales. Only one genus is known, _Pimelepterus_, with six species from
+tropical seas. These fishes are sometimes found at a great distance
+from the land.
+
+
+                     FIFTH FAMILY--HOPLOGNATHIDÆ.
+
+_Body compressed and elevated, covered with very small ctenoid scales.
+Lateral line continuous. The bones of the jaws have a sharp dentigerous
+edge, as in Scarus. The teeth, if at all conspicuous, being continuous
+with the bone, forming a more or less indistinct serrature; no teeth
+on the palate. The spinous portion of the dorsal fin is rather more
+developed than the soft; the spines strong; anal with three spines,
+similar to the soft dorsal. Ventrals thoracic, with one spine and five
+soft rays._
+
+One genus only is known, _Hoplognathus_, with four species from
+Australian, Japanese, and Peruvian coasts.
+
+  [Illustration: Fig. 176.--Teeth of Hoplognathus.]
+
+
+                       SIXTH FAMILY--CIRRHITIDÆ.
+
+_Body oblong, compressed, covered with cycloid scales; lateral
+line continuous. Mouth in front of the snout, with lateral cleft.
+Eye lateral, of moderate size. Cheeks without a bony stay for the
+præoperculum. Generally six, sometimes five or three branchiostegals.
+Dentition more or less complete, composed of small pointed teeth,
+sometimes with the addition of canines. One dorsal fin, formed by a
+spinous and soft portion, of nearly equal development. Anal with three
+spines, generally less developed than the soft dorsal. The lower rays
+of the pectoral fins simple and generally enlarged; ventrals thoracic,
+but remote from the root of the pectorals, with one spine and five
+rays._
+
+The fishes of this family may be readily recognised by their
+thickened, undivided lower pectoral rays, which in some are evidently
+auxiliary organs of locomotion, in others, probably, organs of
+touch. They differ from the following family, the Scorpænidæ, in
+lacking the bony connection between the infraorbital ring and the
+præoperculum. Two groups may be distinguished in this family, which,
+however, are connected by an intermediate genus (_Chironemus_). The
+first, distinguished by the presence of vomerine teeth, consists of
+_Cirrhites_ and _Chorinemus_, small prettily coloured fishes. The
+former genus is peculiar to the Indo-Pacific, and consists of sixteen
+species; the second, with three species, seems to be confined to
+the coasts of Australia and New Zealand. The second group lacks the
+vomerine teeth, and comprises the following genera:--
+
+   CHILODACTYLUS.--One dorsal fin, with from sixteen to nineteen
+   spines; anal fin of moderate length; caudal forked. One of the
+   simple pectoral rays more or less prolonged, and projecting
+   beyond the margin of the fin. Teeth in villiform bands; no
+   canines. Præoperculum not serrated. Scales of moderate size.
+   Air-bladder with many lobes.
+
+  [Illustration: Fig. 177.--_Chilodactylus macropterus_, from
+  Australia.]
+
+Seventeen species are known, chiefly from the temperate parts of the
+Southern Pacific, and also from the coasts of Japan and China. They
+belong to the most valuable food-fishes, as they grow to a considerable
+size (from five to twenty-five lbs.), and are easily caught in
+numbers. At the Cape of Good Hope they are very abundant, and preserved
+in large quantities for export.
+
+_Mendosoma_ from the coast of Chili, and _Nemadactylus_ from Tasmania,
+are allied genera.
+
+   LATRIS.--Dorsal fin deeply notched; the spinous portion with
+   seventeen spines; anal fin many-rayed. None of the simple
+   pectoral rays passes the margin of the fin. Teeth villiform; no
+   canines. Præoperculum minutely serrated. Scales small.
+
+Two species only are known from Tasmania and New Zealand, which belong
+to the most important food-fishes of the Southern Hemisphere. _Latris
+hecateia_ or the “Trumpeter,” ranges from sixty to thirty lbs. in
+weight, and is considered by the colonists the best flavoured of any of
+the fishes of South Australia, Tasmania, and New Zealand, and consumed
+smoked as well as fresh. The second species, _Latris ciliaris_, is
+smaller, scarcely attaining a weight of twenty lbs., but more abundant;
+it is confined to the coast of New Zealand.
+
+  [Illustration: Fig. 178.--Skull of _Scorpæna percoides_;
+  _so_, Suborbital ring; _pr_, Præoperculum; _st_,
+  Bony stay, connecting the sub-orbital with the præoperculum.]
+
+
+                      SEVENTH FAMILY--SCORPÆNIDÆ.
+
+_Body oblong, more or less compressed, covered with ordinary scales,
+or naked. Cleft of the mouth lateral or subvertical. Dentition feeble,
+consisting of villiform teeth; and generally without canines. Some
+bones of the head armed, especially the angle of the præoperculum,
+its armature receiving additional support by a bony stay, connecting
+it with the infraorbital ring. The spinous portion of the dorsal fin
+equally or more developed than the soft and than the anal. Ventrals
+thoracic, generally with one spine and five soft rays, sometimes
+rudimentary._
+
+This family consists of carnivorous marine fishes only; some resemble
+the Sea-Perches in form and habits, as _Sebastes_, _Scorpæna_, etc.,
+whilst others live at the bottom of the sea, and possess in various
+degrees of development those skinny appendages resembling the fronds of
+seaweeds, by which they either attract other fishes, or by which they
+are enabled more effectually to hide themselves. Species provided with
+those appendages have generally a coloration resembling that of their
+surroundings, and varying with the change of locality. The habit of
+living on the bottom has also developed in many Scorpænoids separate
+pectoral rays, by means of which they move or feel. Some of the genera
+live at a considerable depth, but apparently not beyond 300 fathoms.
+Nearly all are distinguished by a powerful armature either of the head,
+or fin spines, or both; and in some the spines have been developed into
+poison organs.
+
+The only fossil representative known at present is a species of
+_Scorpæna_ from the Eocene of Oran.
+
+   SEBASTES.--Head and body compressed; crown of the head scaly to,
+   or even beyond, the orbits; no transverse groove on the occiput.
+   Body covered with scales of moderate or small size, and without
+   skinny tentacles. Fin-rays not elongate; one dorsal, divided by
+   a notch into a spinous and soft portion, with twelve or thirteen
+   spines; the anal with three. No pectoral appendages. Villiform
+   teeth in the jaws, on the vomer, and generally on the palatine
+   bones. Vertebræ more than twenty-four.
+
+About twenty species are known, principally from seas of the temperate
+zones, as from the coasts of Northern Europe (_S. norvegicus_, _S.
+viviparus_), of Japan, California, New Zealand, and Van Diemen’s Land.
+All seem to prefer deep water to the surface, and _Sebastes macrochir_
+has been obtained at a depth of 345 fathoms. In their general form
+they resemble the Sea-Perches, attain to a weight of from one to four
+lbs., and are generally esteemed as food.
+
+   SCORPÆNA.--Head large, slightly compressed, generally with a
+   transverse naked depression on the occiput; bones of the head
+   armed with spines, and generally with skinny tentacles. Scales
+   of moderate size. Mouth large, oblique. Villiform teeth in the
+   jaws, and at least on the vomer. One dorsal, 12–13/9, A. 3/5.
+   Pectoral fins without detached rays, large, rounded, with the
+   lower rays simple and thickened. Air-bladder none. Vertebræ
+   twenty-four.
+
+  [Illustration: Fig. 179.--Head of Scorpæna percoides, from New
+  Zealand.]
+
+  [Illustration: Fig. 180.--Scorpæna bynoensis, from the coasts of
+  Australia.]
+
+About forty species are known from tropical and sub-tropical seas.
+They lead a sedentary life, lying hidden in the sand, or between rocks
+covered with seaweed, watching for their prey, which chiefly consists
+of small fishes. Their strong undivided pectoral rays aid them in
+burrowing in the sand, and in moving along the bottom. The type of
+their coloration is very much the same in all the species, viz. an
+irregular mottling of red, yellow, brown, and black colours, but the
+distribution of these colours varies exceedingly, not only in the same
+species but also in the same individuals. They do not attain to any
+considerable size, probably never exceeding a length of 18 inches.
+Their flesh is well flavoured. Wounds inflicted by their fin-spines are
+exceedingly painful, but not followed by serious consequences.
+
+_Glyptauchen_ and _Lioscorpius_ are genera closely allied to
+_Scorpæna_, from Australian seas.
+
+_Setarches_ is also allied to the preceding genera, and provided with
+very large eyes, in accordance with the depth (215 fathoms) which the
+two species known at present inhabit; one has been found near Madeira,
+the other near the Fiji Islands.
+
+   PTEROIS.--Head and body compressed; scales of small or moderate
+   size. Bones of the head armed with numerous spinous projections,
+   between which often skinny tentacles are developed. The dorsal
+   spines and pectoral rays are more or less prolonged, passing
+   beyond the margin of the connecting membrane. Twelve or thirteen
+   dorsal spines. Villiform teeth in the jaws and on the vomer.
+
+Nine species are known from the tropical Indo-Pacific. They belong
+to the most singularly formed and most beautifully coloured fishes
+of the Tropics, and formerly were believed to be able to fly, like
+Dactylopterus. But the membrane connecting their pectoral rays is
+much too short and feeble to enable them to raise themselves from the
+surface of the water.
+
+   APISTUS.--Head and body compressed, covered with ctenoid scales
+   of rather small size. Some bones of the head, and especially
+   the præorbital, are armed with spines. One dorsal with fifteen
+   spines; the anal with three. The pectoral fin is elongate, and
+   one ray is completely detached from the fin. Villiform teeth in
+   the jaws, on the vomer, and palatine bones. Air-bladder present.
+   A cleft behind the fourth gill.
+
+Two species from the Indian Ocean. These fishes are very small, but
+of interest on account of the prolongation of their pectoral fins,
+which indicates that they can take long flying leaps out of the water.
+However, this requires confirmation by actual observation.
+
+   AGRIOPUS.--Head and body compressed, scaleless; head without
+   any, or with very feeble, armature. Cleft of the mouth small, at
+   the end of the produced snout. One dorsal fin, which commences
+   from the head, the spinous portion being formed by from
+   seventeen to twenty-one strong spines; anal short. Villiform
+   teeth in the jaws, generally none on the vomer.
+
+Seven species. This singular genus is peculiar to the temperate parts
+of the South Pacific, occurring at the Cape, on the coast of South
+Australia, and Chili. The largest species (_A. torvus_) attains a
+length of two and a half feet. Nothing is known of its mode of life.
+
+   SYNANCEIA.--General appearance of the fish, especially of the
+   head, monstrous. Scales none; skin with numerous soft warty
+   protuberances or filaments. Mouth directed upwards, wide. Eyes
+   small. From thirteen to sixteen dorsal spines; pectoral fins
+   very large. Villiform teeth in the jaws, and sometimes on the
+   vomer.
+
+Four species are known from the Indo-Pacific, of which _S. horrida_ and
+_S. verrucosa_ are the most generally distributed, and, unfortunately,
+the most common. They are justly feared on account of the great danger
+accompanying wounds which they inflict with their poisoned dorsal
+spines, as has been already noticed above, p. 191. The greatest length
+to which they attain does not seem to exceed eighteen inches. They are
+very voracious fishes, and their stomach is of so great a capacity that
+they are able to swallow fishes one-third of their own bulk.
+
+   MICROPUS.--Head and body strongly compressed, short, and deep;
+   no scales, but the skin is covered with minute tubercles. Snout
+   very short, with nearly vertical anterior profile. Præorbital,
+   præ- and inter-operculum with spines on the edge. Dorsal fin
+   with seven or eight, anal with two spines. Pectorals short,
+   ventrals rudimentary. Jaws with villiform teeth.
+
+These fishes belong to the smallest of Acanthopterygians, scarcely
+exceeding 1½ inches in length. Two species are known, which are rather
+common on the coral reefs of the Pacific.
+
+   CHORISMODACTYLUS.--Head and body rather compressed,
+   scaleless, with skinny flaps. Bones of the head with prominent
+   ridges; the præorbital, præoperculum, and operculum armed; a
+   depression on the occiput. One dorsal fin, with thirteen spines;
+   the anal with two. Three free pectoral appendages. Ventral fins
+   with one spine and five rays. Villiform teeth in the jaws only.
+
+Only one small species, _Ch. multibarbis_, is known, from the coasts of
+India and China.
+
+  [Illustration: Fig. 181.--Chorismodactylus multibarbis.]
+
+To complete the list of Scorpænoid genera, we have to mention
+_Tænianotus_, _Centropogon_, _Pentaroge_, _Tetraroge_, _Prosopodasys_,
+_Aploactis_, _Trichopleura_, _Hemitripterus_, _Minous_ and _Pelor_.
+
+
+                        EIGHTH FAMILY--NANDIDÆ.
+
+_Body oblong, compressed, covered with scales. Lateral line
+interrupted. Dorsal fin formed by a spinous and soft portion, the
+number of spines and rays being nearly equal; anal fin with three
+spines, and with the soft portion similar to the soft dorsal. Ventral
+fins thoracic, with one spine, and five or four rays. Dentition more or
+less complete, but feeble._
+
+This small family consists of two very distinct groups.
+
+A. _Plesiopina._ Marine fishes of small size, with pseudobranchiæ
+and only four ventral rays. _Plesiops_ from the coral-reefs of the
+Indo-Pacific, and _Trachinops_ from the coast of New South Wales,
+belong to this group.
+
+B. _Nandina._ Freshwater fishes of small size from the East Indies,
+without pseudobranchiæ, and five ventral rays. The genera are _Badis_,
+_Nandus_, and _Catopra_.
+
+
+                      NINTH FAMILY--POLYCENTRIDÆ.
+
+_Body compressed, deep, scaly. Lateral line none. Dorsal and anal
+fins long, both with numerous spines, the spinous portion being the
+more developed. Ventrals thoracic, with one spine and five soft rays.
+Teeth feeble. Pseudobranchiæ hidden._
+
+Only two genera, each represented by one or two species in the Atlantic
+rivers of Tropical America, _Polycentrus_ and _Monocirrhus_,
+belong to this family. They are small insectivorous fishes.
+
+
+                       TENTH FAMILY--TEUTHIDIDÆ.
+
+_Body oblong, strongly compressed, covered with very small scales.
+Lateral line continuous. Eye lateral, of moderate size. A single series
+of cutting incisors in each jaw; palate toothless. One dorsal fin,
+the spinous portion being the more deve__loped; anal with seven
+spines. Ventral fins thoracic, with an outer and an inner spine, and
+with three soft rays between._
+
+This family consists of one very natural genus, _Teuthis_, readily
+recognised by the singular structure of the fins. In all the species
+the fin-formula is D. 13/10. A. 7/9. The incisors are small, narrow,
+and provided with a serrated edge. The air-bladder is large, and
+forked anteriorly as well as posteriorly. Their skeleton shows several
+peculiarities: the number of vertebræ is twenty-three, ten of which
+belong to the abdominal portion. The abdominal cavity is surrounded
+by a complete ring of bones, the second piece of the coracoid being
+exceedingly long, and extending along the whole length of the abdomen,
+where it is joined to a spinous process of the first interhæmal. The
+pubic bones are slender, long, firmly attached to each other, without
+leaving a free space between them. They are fastened by a long process
+which passes the symphysis of the radii, and extends on to that of the
+humeri.
+
+  [Illustration: Fig. 182.--Teuthis nebulosa, Indian Ocean.]
+
+Thirty species are known, all from the Indo-Pacific; but they do not
+extend eastwards beyond 140° long., or to the Sandwich Islands. They
+are herbivorous, and do not exceed a length of fifteen inches.
+
+
+            SECOND DIVISION--ACANTHOPTERYGII BERYCIFORMES.
+
+_Body compressed, oblong, or elevated; head with large muciferous
+cavities which are covered with a thin skin. Ventral fins thoracic,
+with one spine and more than five soft rays_ (_in_ Monocentris _with
+two only_).
+
+One family only belongs to this division.
+
+
+                           FAMILY--BERYCIDÆ.
+
+_Body short, with ctenoid scales, which are rarely absent. Eyes
+lateral, large_ (_except_ Melamphaës). _Cleft of the mouth lateral,
+oblique; jaws with villiform teeth; palate generally toothed. Opercular
+bones more or less armed. Eight (four) branchiostegals._
+
+This family offers several points of biological interest. All
+its members are strictly marine; but only two of the genera are
+surface-forms (_Holocentrum_ and _Myripristis_). All the others
+descend considerably below the surface, and even some of the species
+of _Myripristis_ habitually inhabit depths of from 50 to 100 fathoms.
+_Polymixia_ and _Beryx_ have been found in 345 fathoms. _Melamphaës_
+must live at a still greater depth, as we may infer from the small
+size of its eye; this fish is not likely to come nearer to the surface
+than to about 200 fathoms. The other genera named have extremely large
+eyes, and, therefore, may be assumed to ascend into such superficial
+strata as are still lit up by a certain proportion of sun-rays. The
+highly-developed apparatus for the secretion of superficial mucus, with
+which these fishes are provided, is another sign of their living at a
+greater depth than any of the preceding families of Acanthopterygians.
+In accordance with this vertical distribution, Berycoid fishes have a
+wide horizontal range, and several species occur at Madeira as well as
+in Japan.
+
+Fossil Berycoids show a still greater diversity of form than living;
+they belong to the oldest Teleosteous fishes, the majority of the
+Acanthopterygians found in the chalk being representatives of this
+family. _Beryx_ has been found in several species, with other genera
+now extinct: _Pseudoberyx_, with abdominal ventrals, from Mount
+Lebanon; _Berycopsis_, with cycloid scales; _Homonotus_, _Stenostoma_,
+_Sphenocephalus_, _Acanus_, _Hoplopteryx_, _Platycornus_, with
+granular scales; _Podocys_, with a dorsal fin extending to the neck;
+_Acrogaster_, _Macrolepis_, and _Rhacolepis_, from the chalk of Brazil.
+Species of _Holocentrum_ and _Myripristis_ occur in the Monte Bolca
+formation.
+
+   MONOCENTRIS.--Snout obtuse, convex, short; eye of moderate size.
+   Villiform teeth on the palatine bones, but none on the vomer.
+   Opercular bones without armature. Scales very large, bony,
+   forming a rigid carapace. Ventrals reduced to a single strong
+   spine and a few rudimentary rays.
+
+  [Illustration: Fig. 183.--Monocentris japonicus.]
+
+One species only is known (_M. japonicus_) from the seas off Japan
+and Mauritius. It does not attain to any size, and is not common.
+
+   HOPLOSTETHUS.--Snout very short and obtuse; eye large.
+   Villiform teeth on the palatine bones, but none on the vomer.
+   Operculum unarmed, a strong spine at the scapulary and the angle
+   of the præoperculum. Scales ctenoid, of moderate size; abdominal
+   edge serrated. One dorsal, with six spines; ventrals with six
+   soft rays; caudal deeply forked.
+
+One species only is known (_H. mediterraneus_), which occurs in the
+Mediterranean, the neighbouring parts of the Atlantic, and in the sea
+off Japan.
+
+   TRACHICHTHYS.--Snout very short and obtuse, with prominent chin;
+   eye large. Villiform teeth on the palatine bones and on the
+   vomer. A strong spine at the scapulary and at the angle of the
+   præoperculum. Scales rather small; abdomen serrated. One dorsal,
+   with from three to six spines; ventral with six soft rays.
+   Caudal forked.
+
+Four species are known from New Zealand and Madeira.
+
+_Anoplogaster_ is an allied genus from tropical parts of the
+Atlantic; it is scaleless.
+
+   BERYX.--Snout short, with oblique cleft of the mouth and
+   prominent chin; eye large. Villiform teeth on the palatine bones
+   and vomer. Opercular bones serrated; no spine at the angle of
+   the præoperculum. Scales ctenoid, of moderate or large size. One
+   dorsal, with several spines; ventrals with seven or more soft
+   rays. Anal with four spines; caudal forked.
+
+  [Illustration: Fig. 184.--Beryx decadactylus.]
+
+Five species are known from Madeira, the tropical Atlantic, and
+the seas of Japan and Australia. The species figured is _B.
+decadactylus_, common at Madeira, and occurring near Japan at a
+depth of 345 fathoms; it attains a length of 1½ feet.
+
+   MELAMPHAES.--Head large and thick, with very thin bones, nearly
+   all the superficial bones being transformed into wide muciferous
+   channels. Eye small. Palate toothless; no barbels; opercles not
+   armed. Scales large, cycloid. One dorsal, with six spines; anal
+   spines very feeble; caudal forked. Ventrals with seven rays.
+
+Two species, deep-sea fishes of the Atlantic; they are very scarce, as
+only three or four specimens have been found hitherto.
+
+   POLYMIXIA.--Snout short, with the cleft of the mouth nearly
+   horizontal; eye large. Two barbels at the throat. Opercles
+   without armature. Scales of moderate size. One dorsal. Anal with
+   three or four spines; caudal forked; ventrals with six or seven
+   soft rays.
+
+Three species are known: _P. nobilis_ from Madeira and St. Helena, _P.
+lowei_ from Cuba, and _P. japonica_ from Japan; the latter species from
+a depth of 345 fathoms. Average size eighteen inches.
+
+   MYRIPRISTIS.--Snout short, with oblique cleft of the mouth and
+   prominent chin; eye large or very large. Villiform teeth on the
+   vomer and palatine bones. Opercular bones serrated; præoperculum
+   without spine. Scales large, ctenoid. Two dorsals, the first
+   with ten or eleven spines; anal with four spines; caudal
+   forked; ventrals with seven soft rays. Air-bladder divided by
+   a contraction in two parts, the anterior of which is connected
+   with the organ of hearing.
+
+Eighteen species from the tropical seas of both hemispheres, the
+majority living near the coast at the surface. The coloration is
+(principally) red or pink on the back and silvery on the sides. They
+attain a length of about 15 inches, and are esteemed as food.
+
+   HOLOCENTRUM.--Snout somewhat projecting, with the cleft of
+   the mouth nearly horizontal; eye large. Villiform teeth on
+   the vomer and palatine bones. Opercular bones and præorbital
+   serrated; operculum with two spines behind; a large spine at the
+   angle of the præoperculum. Scales ctenoid, of moderate size. Two
+   dorsals, the first with twelve spines; anal with four spines,
+   the third being very long and strong; caudal forked. Ventrals
+   with seven soft rays.
+
+  [Illustration: Fig. 185.--_Holocentrum unipunctatum_, from
+  the South Sea.]
+
+About thirty species are known from the tropical seas of both
+hemispheres; all are surface fishes, and very common. The young have
+the upper part of the snout pointed and elongate, and were described as
+a distinct genus (_Rhynchichthys_). The coloration of the adult is
+uniform; red, pink, and silvery prevailing. They attain to a length of
+about 15 inches, and are esteemed as food.
+
+
+             THIRD DIVISION--ACANTHOPTERYGII KURTIFORMES.
+
+_One dorsal fin only, much shorter than the anal, which is long and
+many-rayed. No superbranchial organ._
+
+One family only belongs to this division.
+
+
+                           FAMILY--KURTIDÆ.
+
+_Body compressed, oblong, deep in front, attenuated behind. Snout
+short. The spines of the short dorsal are few in number, if developed.
+Scales small or of moderate size. Villiform teeth in the jaws, on the
+vomer, and palatine bones._
+
+This family consists of a small number of species only, which form
+two distinct genera, _Pempheris_ and _Kurtus_. They are shore fishes
+of tropical seas. In both the air-bladder shows some peculiarity: in
+_Pempheris_ it is divided into an anterior and posterior portion; in
+_Kurtus_ it is lodged within the ribs, which are dilated, convex,
+forming rings. The number of vertebræ is respectively twenty-four and
+twenty-three.
+
+
+           FOURTH DIVISION--ACANTHOPTERYGII POLYNEMIFORMES.
+
+_Two rather short dorsal fins, somewhat remote from each other; free
+filaments at the humeral arch, below the pectoral fins; muciferous
+canals of the head well developed._
+
+One family only belongs to this division.
+
+
+                          FAMILY--POLYNEMIDÆ.
+
+_Body oblong, rather compressed, covered with smooth or very feebly
+ciliated scales. Lateral line continuous. Snout projecting beyond the
+mouth, which is inferior, with lateral cleft. Eye lateral, large.
+Villiform teeth in the jaws and on the palate. Ventrals thoracic, with
+one spine and five rays._
+
+The fishes of this natural family have been divided, on slight
+differences, into three genera--_Polynemus_, _Pentanemus_, and
+_Galeoides_. They are found in rather numerous species on the coasts
+between the tropics, and the majority enter brackish or even fresh
+water. Very characteristic are the free filaments which in this family
+are organs of touch; they are inserted on the humeral arch at some
+distance from the pectoral fin; but, nevertheless, can be regarded
+only as a detached portion of that fin; they can be moved quite
+independently of the fin; their number varies from three to fourteen,
+according to the species; in some they are exceedingly elongate, twice
+as long as the fish, in others they are not longer or even shorter than
+the pectoral. It is evident from the whole organisation of these fishes
+that they live on muddy bottom or in thick water, such as is found
+near the mouths of great rivers. Their eyes are large, but generally
+obscured by a filmy skin, so that those feelers must be of great use
+to them in finding their way and their food. The Polynemoids are very
+useful to man: their flesh is esteemed, and some of the species are
+provided with an air-bladder which yields a good sort of isinglass,
+and forms an article of trade in the East Indies. Some of these fishes
+attain to a length of four feet.
+
+  [Illustration: Fig. 186.--_Pentanemus quinquarius_, from the
+  West Coast of Africa and the West Indies.]
+
+
+             FIFTH DIVISION--ACANTHOPTERYGII SCIÆNIFORMES.
+
+_The soft dorsal is more, generally much more, developed than the
+spinous, and than the anal. No pectoral filaments; head with the
+muciferous canals well developed._
+
+Also this division is composed of one family only.
+
+
+                           FAMILY--SCIÆNIDÆ.
+
+_Body rather elongate, compressed, covered with ctenoid scales.
+Lateral line continuous, and frequently extending over the caudal fin.
+Mouth in front of the snout. Eye lateral, of moderate size. Teeth in
+villiform bands, sometimes with the addition of canines; no molars or
+incisor-like teeth in the jaws; palate toothless. Præoperculum unarmed,
+and without bony stay. Ventrals thoracic, with one spine and five soft
+rays. Bones of the head with wide muciferous channels. Stomach coecal.
+Air-bladder frequently with numerous appendages_ (see pp. 144 and
+_seq._)
+
+The fishes of the “_Meagre_” family are chiefly coast-fishes of the
+tropical and sub-tropical Atlantic and Indian Oceans, preferring the
+neighbourhood of the mouths of large rivers, into which they freely
+enter, some of the species having become so completely naturalised in
+fresh water that they are never found nowadays in the sea. Some of the
+larger species wander far from their original home, and are not rarely
+found at distant localities as occasional visitors. In the Pacific
+and on the coast of Australia, where but a few large rivers enter the
+ocean, they are extremely rare and, in the Red Sea, they are absent.
+Many attain a large size, and almost all are eaten.
+
+No fossil species have been as yet discovered.
+
+   POGONIAS.--Snout convex, with the upper jaw overlapping the
+   lower. Mandible with numerous small barbels. No canines. The
+   first dorsal with ten stout spines. Two anal spines, the second
+   very strong. Scales of moderate size.
+
+To this fish (_P. chromis_) more especially is given the name of
+“Drum,” from the extraordinary sounds which are produced by it and
+other allied Sciænoids. These sounds are better expressed by the word
+drumming than by any other, and are frequently noticed by persons in
+vessels lying at anchor on the coasts of the United States, where those
+fishes abound. It is still a matter of uncertainty by what means the
+“Drum” produces the sounds. Some naturalists believe that it is caused
+by the clapping together of the pharyngeal teeth, which are very large
+molar teeth. However, if it be true that the sounds are accompanied
+by a tremulous motion of the vessel, it seems more probable that they
+are produced by the fishes beating their tails against the bottom of
+the vessel in order to get rid of the parasites with which that part
+of their body is infested. The “Drum” attains to a length of more than
+four feet, and to a weight exceeding a hundred lbs. Its air-bladder has
+been figured on p. 146.
+
+_Micropogon_ is closely allied to _Pogonias_, but has conical
+pharyngeal teeth. Two species from the western parts of the Atlantic.
+
+  [Illustration: Fig. 187.--Pharyngeal bones and teeth of
+  _Pogonias chromis_. A, Upper; B, Lower pharyngeals.]
+
+   UMBRINA.--Snout convex, with the upper jaw overlapping the
+   lower; a short barbel under the symphysis of the mandible. The
+   first dorsal with nine or ten flexible spines, the anal with one
+   or two. Scales of moderate size.
+
+  [Illustration: Fig. 188.--_Umbrina nasus_, from Panama.]
+
+Twenty species are known from the Mediterranean, Atlantic, and Indian
+Ocean. One well known to the ancients, under the name of _Umbra_, is
+the _Umbrina cirrhosa_ of the Mediterranean, the “Umbrine” or “Ombre”
+of the French, and the “Corvo” of the Italians. It ranges to the Cape
+of Good Hope, and attains a length of three feet. Also on the coasts
+of the United States several species occur, as _U. alburna_, _U.
+nebulosa_, etc.
+
+  [Illustration: Fig. 189.--_Umbrina nasus_, from Panama.]
+
+   SCIÆNA (including _Corvina_).--The upper jaw overlapping
+   the lower, or both jaws equal in front. Interorbital space
+   moderately broad and slightly convex. Cleft of the mouth
+   horizontal or slightly oblique. The outer series of teeth is
+   generally composed of teeth larger than the rest, but there are
+   no canines. Eye of moderate size, barbel none.
+
+  [Illustration: Fig. 190.--Sciæna richardsonii.]
+
+Some fifty species are known, but their distinctive characters have
+been but imperfectly pointed out. They are found in all the seas
+and rivers in which Sciænoids generally occur, and many are entirely
+confined to fresh water, for instance the species figured, _Sciæna
+richardsonii_, from Lake Huron; _Sc. amazonica_; _Sc. obliqua_,
+_ocellata_, _oscula_, etc., from fresh waters of the United States.
+_Sciæna diacanthus_ and _Sc. coitor_ belong to the most common fishes
+of the coasts of the East Indies, ascending the great rivers for a long
+distance from the sea. One of the European species, _Sciæna aquila_,
+has an extremely wide range; it not rarely reaches the British coasts,
+where it is known as “Meagre,” and has been found at the Cape of Good
+Hope and on the coast of southern Australia. Like some of the other
+species it attains to a length of six feet, but the majority of the
+species of this genus remain within smaller dimensions. A part of the
+species have the second anal ray very strong, and have been placed into
+a distinct genus, _Corvina_,--thus, among others, _Sc. nigra_ from the
+Mediterranean, and _Sc. richardsonii_.
+
+_Pachyurus_ is closely allied to _Sciæna_, but has the vertical fins
+densely covered with small scales.
+
+   OTOLITHUS.--Snout obtuse or somewhat pointed, with the lower jaw
+   longer. The first dorsal with nine or ten feeble spines. Canine
+   teeth more or less distinct. Præoperculum denticulated. Scales
+   of moderate or small size.
+
+About twenty species are known from the tropical and sub-tropical parts
+of the Atlantic and Indian Oceans. The air-bladder is figured on p. 144.
+
+   ANCYLODON differs from _Otolithus_ in having very long
+   arrow-shaped or lanceolate canine teeth. Coasts of tropical
+   America.
+
+   COLLICHTHYS.--Body elongate; head very broad, with the upper
+   surface very convex; cleft of the mouth wide and oblique;
+   no large canines. Eye small. No barbel. Scales small, or of
+   moderate size. The second dorsal very long, caudal pointed.
+
+Three species from the East Indian and Chinese coasts. The great
+development of the muciferous system on the head and the small eye
+leads one to suppose that these fishes live in muddy water near the
+mouths of large rivers. The air-bladder has been described on p. 144.
+
+Other genera belonging to this family are _Larimus_, _Eques_, _Nebris_,
+and _Lonchurus_.
+
+  [Illustration: Fig. 191.--Histiophorus pulchellus.]
+
+
+             SIXTH DIVISION--ACANTHOPTERYGII XIPHIIFORMES.
+
+_The upper jaw is produced into a long cuneiform weapon._
+
+These fishes form one small family only, _Xiphiidæ_.
+
+The “Sword-fishes” are pelagic fishes, occurring in all tropical and
+sub-tropical seas. Generally found in the open ocean, always vigilant,
+and endowed with extraordinary strength and velocity, they are but
+rarely captured, and still more rarely preserved. The species found
+in the Indian and Pacific Oceans belong to the genus _Histiophorus_,
+distinguished from the common Mediterranean Sword-fish, or _Xiphias_,
+by the presence of ventral fins, which, however, are reduced to two
+long styliform appendages. The distinction of the species is beset with
+great difficulties, owing to the circumstance that but few examples
+exist in museums, and further, because the form of the dorsal fin,
+the length of the ventrals, the shape and length of the sword, appear
+to change according to the age of the individuals. Some specimens or
+species have only the anterior dorsal rays elevated, the remainder of
+the fin being very low, whilst in others all the rays are exceedingly
+elongate, so that the fin, when erected, projects beyond the surface of
+the water. It is stated that Sword-fishes, when quietly floating with
+the dorsal fin erect, can sail before the wind, like a boat.
+
+Sword-fishes are the largest of Acanthopterygians, and not exceeded in
+size by any other Teleostean; they attain to a length of from 12 to 15
+feet, and swords have been obtained more than three feet long, and with
+a diameter of at least three inches at the base. The sword is formed by
+the prolongation and coalescence of the maxillary and intermaxillary
+bones; it is rough at its lower surface, owing to the development
+of rudimentary villiform teeth, very hard and strong, and forms a
+most formidable weapon. Sword-fishes never hesitate to attack whales
+and other large Cetaceans, and by repeatedly stabbing these animals
+generally retire from the combat victorious. The cause which excites
+them to those attacks is unknown; but they follow this instinct so
+blindly that they not rarely attack boats or large vessels in a similar
+manner, evidently mistaking them for Cetaceans. Sometimes they actually
+succeed in piercing the bottom of a ship, endangering its safety; but
+as they are unable to execute powerful backward movements they cannot
+always retract their sword, which is broken off by the exertions of the
+fish to free itself. A piece of a two-inch plank of a whale-boat, thus
+pierced by a sword-fish, in which the broken sword still remains, is
+preserved in the British Museum.
+
+The Rev. Wyatt Gill, who has worked as a missionary for many years in
+the South Sea Islands, communicates that young Sword-fishes are easily
+caught in strong nets, but no net is strong enough to hold a fish of
+six feet in length. Specimens of that size are now and then captured
+by hook and line, a small fish being used as bait. Individuals with
+the sword broken off are not rarely observed. Larger specimens cannot
+be captured by the natives, who are in great fear of them. They easily
+pierce their canoes, and only too often dangerously wound persons
+sitting in them.
+
+The Mediterranean Sword-fish is constantly caught in the nets of the
+Tunny-fishers off the coast of Sicily, and brought to market, where its
+flesh sells as well as that of the Tunny.
+
+The remarkable changes which Sword-fishes undergo at an early stage of
+their growth have been noticed above, p. 173 and _seq._
+
+Sword-fishes are as old a type as the Berycoids. Their remains have
+been found in the chalk of Lewes, and more frequently in the London
+clay of Sheppy, where an extinct genus, _Coelorhynchus_, has been
+recognised.
+
+
+          SEVENTH DIVISION--ACANTHOPTERYGII TRICHIURIFORMES.
+
+_Body elongate, compressed or band-like; cleft of the mouth wide,
+with several strong teeth in the jaws or on the palate. The spinous
+and soft portions of the dorsal fin and the anal are of nearly equal
+extent, long, many-rayed, sometimes terminating in finlets; caudal fin
+forked, if present._
+
+
+                         FAMILY--TRICHIURIDÆ.
+
+Marine fishes inhabiting the tropical and sub-tropical seas; some of
+them are surface-fishes, living in the vicinity of the coast, whilst
+others descend to moderate depths, as the Berycoids. All are powerful
+rapacious fishes, as is indicated by their dentition.
+
+The oldest of the extinct genera are _Enchodus_ and _Anenchelum_; they
+were formerly referred to the Scombroids, but belong to this family.
+The former has been found in the chalk of Lewes and Mæstricht; the
+latter is abundant in the Eocene schists of Glaris. _Anenchelum_ is
+much elongate, and exhibits in the slender structure of its bones the
+characteristics of a deep-sea fish; it resembles much _Lepidopus_,
+but has some long rays in the ventrals. Other Eocene genera are
+_Nemopteryx_ and _Xiphopterus_. In the Miocene of Licata in Sicily
+_Trichiuridæ_ are well represented, viz. by a species of _Lepidopus_,
+and by two genera, _Hemithyrsites_ and _Trichiurichthys_, which are
+allied to _Thyrsites_ and _Trichiurus_, but covered with scales.
+
+The following is a complete list of the genera referred to this
+family:--
+
+   NEALOTUS.--Body incompletely clothed with delicate scales. Small
+   teeth in the jaws and on the palatine bones; none on the vomer.
+   Two dorsal fins, the first continuous and extending to the
+   second; finlets behind the second and anal fins. Each ventral
+   fin represented by a single small spine. A dagger-shaped spine
+   behind the vent. Caudal fin well developed.
+
+One specimen only of this fish (_N. tripes_), 10 inches long, has
+been obtained off Madeira; it evidently lives at a considerable depth,
+and comes to the surface only by accident.
+
+   NESIARCHUS.--Body covered with small scales. Several strong
+   fangs in the jaws; no teeth on the palate. First dorsal not
+   extending to the second. No detached finlets. Ventrals small,
+   but perfectly developed, thoracic. Caudal fin present. A
+   dagger-shaped spine behind the vent.
+
+A rather large fish (_N. nasutus_), very rarely found in the sea
+off Madeira. The two or three specimens found hitherto measure from
+three to four feet in length. Probably living at the same depth as the
+preceding genus.
+
+   APHANOPUS.--Scales none. Two very long dorsal fins; caudal well
+   developed; ventrals none. A strong dagger-shaped spine behind
+   the vent. Strong teeth in the jaws; none on the palate.
+
+One species only is known, named _A. carbo_ from its coal-black
+colour; it is evidently a deep-sea fish, very rarely obtained in the
+sea off Madeira. Upwards of four feet long.
+
+   EUOXYMETOPON.--Body naked, very long and thin. Profile of the
+   head regularly decurved from the nape to the snout, the occiput
+   and forehead being elevated and trenchant. Jaws with fangs;
+   palatine teeth present. One dorsal only, continued from the head
+   to the caudal fin, which is distinct. A dagger-shaped spine
+   behind the vent. Pectoral fins inserted almost horizontally,
+   with the lowest rays longest, and with the posterior border
+   emarginate. Ventral fins rudimentary, scale-like.
+
+This is another deep-sea form of this family, but, at present, no
+observations have been made as regards the exact depth at which it
+occurs. A specimen has been known since the year 1812; it was found on
+the coast of Scotland, and described as _Trichiurus lepturus_. The
+same species has been re-discovered in the West Indies, where, however,
+it is also extremely scarce.
+
+   LEPIDOPUS.--Body band-like; one single dorsal extends along
+   the whole length of the back; caudal well developed. Ventrals
+   reduced to a pair of scales. Scales none. Several fangs in the
+   jaws; teeth on the palatine bones.
+
+  [Illustration: Fig. 192.--Lepidopus caudatus.]
+
+The Scabbard-fish (_L. caudatus_) is rather common in the Mediterranean
+and warmer parts of the Atlantic, extending northwards to the south
+coast of England, where it is an occasional visitor, and southwards
+to the Cape of Good Hope. More recently it has been observed on the
+coasts of Tasmania and New Zealand. We may, therefore, justly consider
+it to be a deep-sea fish, which probably descends to the same depth as
+the preceding allied forms. It grows to a length of five or six feet,
+but its body is so much compressed that it does not weigh more than
+as many pounds. It is well known in New Zealand, where it is called
+“Frost-fish,” and esteemed as the most delicious fish of the colony.
+A still more attenuated species (_L. tenuis_) occurs in the sea off
+Japan, at a depth of some 340 fathoms.
+
+   TRICHIURUS.--Body band-like, tapering into a fine point, without
+   caudal fin. One single dorsal extending the whole length of the
+   back. Ventrals reduced to a pair of scales, or entirely absent.
+   Anal fin rudimentary, with numerous extremely short spines,
+   scarcely projecting beyond the skin. Long fangs in the jaws;
+   teeth on the palatine bones, none on the vomer.
+
+The “Hairtails” belong to the tropical marine fauna, and although
+generally found in the vicinity of land, they wander frequently out to
+sea, perhaps merely because they follow some ocean-currents. Therefore
+they are not rarely found in the temperate zone, the common West Indian
+species (_T. lepturus_), for instance, on the coast of England. They
+attain to a length of about four feet. The number of their vertebræ is
+very large, as many as 160, and more. Six species are known.
+
+   EPINNULA.--Body rather elongate, covered with minute scales,[*.
+   see below] The first dorsal fin continuous, with spines of
+   moderate strength, and extending on to the second; finlets none;
+   ventrals well developed. Lateral lines two. Teeth of the jaws
+   strong; palatine teeth, none.
+
+The “Domine” of the Havannah, _E. magistralis_.
+
+   THYRSITES.--Body rather elongate, for the greater part naked.
+   The first dorsal continuous, with the spines of moderate
+   strength, and extending on to the second. From two to six
+   finlets behind the dorsal and anal. Several strong teeth in the
+   jaws; teeth on the palatine bones.
+
+The species of this genus attain to a considerable size (from four to
+five feet), and are valuable food fishes; _Th. atun_ from the Cape
+of Good Hope, South Australia, New Zealand, and Chili, is preserved,
+pickled or smoked. In New Zealand it is called “Barracuda” or “Snoek,”
+and exported from the colony into Mauritius and Batavia as a regular
+article of commerce, being worth over £17 a ton; _Th. pretiosus_, the
+“Escholar” of the Havannah, from the Mediterranean, the neighbouring
+parts of the Atlantic, and the West Indies; _Th. prometheus_ from
+Madeira, Bermuda, St. Helena, and Polynesia; _Th. solandri_ from
+Amboyna and Tasmania is probably the same as _Th. prometheus_.
+
+Young specimens of this (or, perhaps, the following) genus have been
+described as _Dicrotus_. In them the finlets are not yet detached
+from the rest of the fin; and the ventral fins, which are entirely
+obsolete in the adult fish, are represented by a long crenulated spine.
+
+   GEMPYLUS.--Body very elongate, scaleless. The first dorsal fin
+   continuous, with thirty and more spines, and extending on to the
+   second. Six finlets behind the dorsal and anal. Several strong
+   teeth in the jaws, none on the palate.
+
+One species (_G. serpens_), inhabiting considerable depths of the
+Atlantic and Pacific Oceans.
+
+                        FAMILY--PALÆORHYNCHIDÆ.
+
+This family has been formed for two extinct genera:
+_Palæorhynchus_ from the schists of Glaris, and
+_Hemirhynchus_ from tertiary formations near Paris. These genera
+resemble much the _Trichiuridæ_ in their long, compressed body,
+and long vertical fins, but their jaws, which are produced into a long
+beak, are toothless, or provided with very small teeth. The dorsal fin
+extends the whole length of the back, and the anal reaches from the
+vent nearly to the caudal, which is forked. The ventrals are composed
+of several rays and thoracic. The vertebræ long, slender, and numerous,
+and, like all the bones of the skeleton, thin, indicating that these
+fishes were inhabitants of considerable depths of the ocean. Both
+the jaws of _Palæorhynchus_ are prolonged into a beak, whilst in
+_Hemirhynchus_ the upper exceeds the lower in length.
+
+
+         EIGHTH DIVISION--ACANTHOPTERYGII COTTO-SCOMBRIFORMES.
+
+_Spines developed, in one of the fins at least. Dorsal fins either
+continuous or close together; the spinous dorsal, if present, always
+short; sometimes modified into tentacles, or into a suctorial disk;
+soft dorsal always long, if the spinous is absent; anal similarly
+developed as the soft dorsal, and both generally much longer than
+the spinous, sometimes terminating in finlets. Ventrals, thoracic or
+jugular, if present, never modified into an adhesive apparatus. No
+prominent anal papilla._
+
+Marine fishes, with few exceptions.
+
+
+                       FIRST FAMILY--ACRONURIDÆ.
+
+_Body compressed, oblong or elevated, covered with minute scales.
+Tail generally armed with one or more bony plates or spines, which
+are developed with age, but absent in very young individuals. Eye
+lateral, of moderate size. Mouth small; a single series of more or
+less compressed, sometimes denticulated, sometimes pointed incisors in
+each jaw; palate toothless. One dorsal fin, the spinous portion being
+less developed than the soft; anal with two or three spines; ventral
+fins thoracic. Air-bladder forked posteriorly. Intestines with more
+or less numerous circumvolutions. Nine abdominal, and thirteen caudal
+vertebræ._
+
+Inhabitants of the tropical seas, and most abundant on coral-reefs.
+They feed either on vegetable substances or on the superficial animal
+matter of corals.
+
+Extinct species of _Acanthurus_ and _Naseus_ have been discovered in
+the Monte Bolca formation.
+
+   ACANTHURUS.--Jaws with a single series of lobate incisors, which
+   are sometimes movable. An erectile spine hidden in a groove on
+   each side of the tail. Ventral fins with one spine and generally
+   five rays. Scales ctenoid, sometimes with minute spines.
+   Branchiostegals five.
+
+The fishes of this genus, which sometimes are termed “Surgeons,”
+are readily recognised by the sharp lancet-shaped spine with which
+each side of the tail is armed. When at rest the spine is hidden
+in a sheath; but it can be erected and used by the fish as a very
+dangerous weapon, by striking with the tail towards the right and
+left. “Surgeons” occur in all tropical seas, with the exception of the
+eastern part of the Pacific, where they disappear with the corals. They
+do not attain to any size, the largest species scarcely exceeding a
+length of eighteen inches. Many are agreeably or showily coloured, the
+ornamental colours being distributed in very extraordinary patterns.
+The larger species are eatable, and some even esteemed as food. It
+is stated that the fry of some species periodically approaches, in
+immense numbers, the coasts of some of the South Sea Islands (Caroline
+Archipelago), and serves as an important article of food to the
+natives. Nearly fifty species are known.
+
+  [Illustration: Fig. 193.--Acanthurus leucosternum, Indian Ocean.]
+
+At an early period of their growth these fishes present so different an
+aspect that they were considered a distinct genus, _Acronurus_.
+The form of the body is more circular and exceedingly compressed. No
+scales are developed, but the skin forms numerous oblique parallel
+folds. The gill-cover and the breast are shining silvery.
+
+   NASEUS.--Tail with two (rarely one or three) bony keeled plates
+   on each side (in the adult). Head sometimes with a bony horn or
+   crest-like prominence directed forwards. Ventral fins composed
+   of one spine and three rays. From four to six spines in the
+   dorsal; two anal spines. Scales minute, rough, forming a sort of
+   fine shagreen. Air-bladder forked behind. Intestinal tract with
+   many circumvolutions.
+
+Twelve species are known from the tropical Indo-Pacific, but none
+of them extend eastwards beyond the Sandwich Islands. In their mode
+of life these fishes resemble the _Acanthuri_. Likewise, the young
+have a very different appearance, and are unarmed, and were described
+as a distinct genus, _Keris_. One of the most common species is _N.
+unicornis_, which, when adult (22 inches long), has a horn about 2
+inches long, whilst it is merely a projection in front of the eye in
+individuals of 7 inches in length.
+
+_Prionurus_ is an allied genus with a series of several keeled bony
+laminæ on each side of the tail.
+
+  [Illustration: Fig. 194.--Naseus unicornis.]
+
+
+                       SECOND FAMILY--CARANGIDÆ.
+
+_Body more or less compressed, oblong or elevated, covered with small
+scales or naked; eye, lateral. Teeth, if present, conical. No bony
+stay for the præoperculum. The spinous dorsal is less developed than
+the soft or than the anal, either continuous with, or separated from,
+the soft portion; sometimes rudimentary. Ventrals thoracic, sometimes
+rudimentary or entirely absent. No prominent papilla near the vent.
+Gill-opening wide. Ten abdominal and fourteen caudal vertebræ._
+
+  [Illustration: Fig. 195.--Semiophoris velitans.]
+
+Inhabitants of tropical and temperate seas. Carnivorous. They appear
+first in cretaceous formations, where they are represented by
+_Platax_ and some Caranx-like genera (_Vomer_ and _Aipichthys_ from
+the chalk of Comen in Istria). They are more numerous in various
+Tertiary formations, especially in the strata of Monte Bolca, where
+some still existing genera occur, as _Zanclus_, _Platax_, _Caranx_
+(_Carangopsis_), _Argyriosus_ (_Vomer_), _Lichia_, _Trachynotus_. Of
+the extinct genera the following belong to this family:--_Pseudovomer_
+(_Licata_), _Amphistium_, _Archæus_, _Ductor_, _Plionemus_ (?), and
+_Semiophorus_. _Equula_ has been recently discovered in the Miocene
+marls of Licata in Sicily.
+
+   CARANX (including _Trachurus_).--Body more or less compressed,
+   sometimes sub-cylindrical. Cleft of the mouth of moderate width.
+   The first dorsal fin continuous, with about eight feeble spines,
+   sometimes rudimentary; the soft dorsal and anal are succeeded
+   by finlets in a few species. Two anal spines, somewhat remote
+   from the fin. Scales very small. Lateral line with an anterior
+   curved, and a posterior straight, portion, either entirely or
+   posteriorly only covered by large plate-like scales, several
+   of which are generally keeled, the keel ending in a spine.
+   Dentition feeble. Air-bladder forked posteriorly.
+
+  [Illustration: Fig. 196.--Plates of the lateral line of Caranx
+  hippos.]
+
+The “Horse-mackerels” are found in abundance in almost all temperate
+and, especially, tropical seas. Many species wander to other parts
+of the coast, or to some distance from land, and have thus gradually
+extended their range over two or more oceanic areas; some are found
+in all tropical seas. The species described are very numerous, about
+ninety having been properly characterised and distinguished. Some
+attain to a length of three feet and more, and all are eatable. They
+feed on other fish and various marine animals.
+
+Of the most noteworthy species the following may be mentioned:--_C.
+trachurus_, the common British Horse-mackerel, distinguished by having
+the lateral line in its whole length armed with large vertical plates;
+it is almost cosmopolitan within the temperate and tropical zones
+of the northern and southern hemispheres. _C. crumenophthalmus_,
+_C. carangus_, and _C. hippos_, three of the most common sea-fishes,
+equally abundant in the Atlantic and Indo-Pacific oceans; _C. ferdau_,
+from the Indo-Pacific, upwards of three feet in length. _C. armatus_,
+_ciliaris_, _gallus_, etc., which have an exceedingly short and
+compressed body, with rudimentary spinous dorsal fin, and with some of
+the rays of the dorsal and anal prolonged into filaments.
+
+  [Illustration: Fig. 197.--Caranx ferdau.]
+
+   ARGYRIOSUS is closely allied to _Caranx_, especially to the
+   last-named species, but the lateral line has no plates whatever;
+   and the body is scaleless, chiefly of a bright silvery colour.
+
+Two species from the tropical Atlantic.
+
+   MICROPTERYX.--Body much compressed, with prominent trenchant
+   abdomen, covered with small scales; lateral line not shielded;
+   præopercular margin entire. Cleft of the mouth rather small;
+   præorbital of moderate width. The first dorsal continuous, with
+   seven feeble spines. No detached finlets. Small teeth on the
+   vomer and palatine bones.
+
+_Micropteryx chrysurus_ is a semi-pelagic fish, and very common in
+the tropical Atlantic, less so in the Indian Ocean.
+
+   SERIOLA.--Body oblong, slightly compressed, with rounded
+   abdomen, covered with very small scales; lateral line not
+   shielded; præopercular margin entire. Cleft of the mouth of
+   moderate width, or rather wide. The first dorsal continuous,
+   with feeble spines. No detached finlets. Villiform teeth in the
+   jaws, on the vomer and palatine bones.
+
+These fishes are often called “Yellow-tails,” and occur in nearly
+all the temperate and tropical seas, sometimes at a great distance
+from land. Twelve species are known, and the majority have a wide
+geographical range. The larger grow to a length of from four to five
+feet, and are esteemed as food, especially at St. Helena, the Cape of
+Good Hope, in Japan, Australia, and New Zealand.
+
+_Seriolella_ and _Seriolichthys_, the latter from the Indo-Pacific, and
+distinguished by a finlet behind the dorsal and anal, are allied genera.
+
+   NAUCRATES.--Body oblong, sub-cylindrical, covered with
+   small scales; a keel on each side of the tail. The spinous
+   dorsal consists of a few short free spines; finlets none.
+   Villiform teeth in the jaws, on the vomer and palatine bones.
+
+The “Pilot-fish” (_N. ductor_) is a truly pelagic fish, known in
+all tropical and temperate seas. Its name is derived from its habit of
+keeping company with ships and large fish, especially Sharks. It is the
+_Pompilus_ of the ancients, who describe it as pointing out the
+way to dubious or embarrassed sailors, and as announcing the vicinity
+of land by its sudden disappearance. It was therefore regarded as a
+sacred fish. The connection between the Shark and the Pilot-fish has
+received various interpretations, some observers having perhaps added
+more sentiment than is warranted by the actual facts. It was stated
+that the Shark never seized the Pilot-fish, that the latter was of
+great use to its big companion in conducting it and showing it the way
+to its food. Dr. Meyen in his “Reise um die Erde” states: “The pilot
+swims constantly in front of the Shark; we ourselves have seen three
+instances in which the Shark was led by the Pilot. When the Shark
+neared the ship the Pilot swam close to the snout, or near one of the
+pectoral fins of the animal. Sometimes he darted rapidly forwards or
+sidewards as if looking for something, and constantly went back again
+to the Shark. When we threw overboard a piece of bacon fastened on a
+great hook, the Shark was about twenty paces from the ship. With the
+quickness of lightning the Pilot came up, smelt at the dainty, and
+instantly swam back again to the Shark, swimming many times round his
+snout and splashing, as if to give him exact information as to the
+bacon. The Shark now began to put himself in motion, the Pilot showing
+him the way, and in a moment he was fast upon the hook.[42] Upon a
+later occasion we observed two Pilots in sedulous attendance on a Blue
+Shark, which we caught in the Chinese Sea. It seems probable that the
+Pilot feeds on the Sharks’ excrements, keeps his company for that
+purpose, and directs his operations solely from this selfish view.” We
+believe that Dr. Meyen’s opinion, as expressed in his last words, is
+perfectly correct. The Pilot obtains a great part of his food directly
+from the Shark, in feeding on the parasitic crustaceans with which
+Sharks and other large fish are infested, and on the smaller pieces of
+flesh which are left unnoticed by the Shark when it tears its prey.
+The Pilot also, being a small fish, obtains greater security when in
+company of a Shark, which would keep at a distance all other fishes of
+prey that would be likely to prove dangerous to the Pilot. Therefore,
+in accompanying the Shark, the Pilot is led by the same instinct which
+makes it follow a ship. With regard to the statement that the Pilot
+itself is never attacked by the Shark all observers agree as to its
+truth; but this may be accounted for in the same way as the impunity
+of the swallow from the hawk, the Pilot-fish being too nimble for the
+unwieldy Shark.
+
+The Pilot-fish does not always leave the vessels on their approach
+to land. In summer, when the temperature of the sea-water is several
+degrees above the average, Pilots will follow ships to the south
+coast of England into the harbour, where they are generally speedily
+caught. Pilot-fish attain a length of 12 inches only. When very young
+their appearance differs so much from the mature fish that they have
+been described as a distinct genus, _Nauclerus_. This fry is
+exceedingly common in the open ocean, and constantly obtained in the
+tow-net; therefore the Pilot-fish retains its pelagic habits also
+during the spawning season, and some of the spawn found by voyagers
+floating on the surface is, without doubt, derived from this species.
+
+CHORINEMUS.--Body compressed, oblong; covered with small scales,
+singularly shaped, lanceolate, and hidden in the skin. The first dorsal
+is formed by free spines in small numbers; the posterior rays of the
+second dorsal and anal are detached finlets. Small teeth in the jaws,
+on the vomer and palatine bones.
+
+Twelve species are known from the Atlantic and Indo-Pacific; some enter
+brackish water, whilst others are more numerous at some distance from
+the shore. They attain to a length of from 2 to 4 feet. In the young,
+which have been described as _Porthmeus_, the spines and finlets are
+connected by membrane with the rest of the fin.
+
+_Lichia_ is an allied genus from the Mediterranean, tropical Atlantic,
+and the coast of Chili; five species.
+
+   TEMNODON.--Body oblong, compressed, covered with cycloid scales
+   of moderate size. Cleft of the mouth rather wide. Jaws with
+   a series of strong teeth; smaller ones on the vomer and the
+   palatine bones. The first dorsal with eight feeble spines
+   connected by membrane; finlets none. Lateral line not shielded.
+   The second dorsal and anal covered with very small scales.
+
+_Temnodon saltator_, sometimes called “Skip-jack,” is spread over
+nearly all the tropical and sub-tropical seas; it frequents principally
+the coasts, but is also met with in the open sea. On the coasts of the
+United States it is well known by the name of “Blue-fish,” being highly
+esteemed as food, and furnishing excellent sport. It is one of the most
+rapacious fishes, destroying an immense number of other shore-fishes,
+and killing many more than they can devour. It grows to a length of 5
+feet, but the majority of those brought to market are not half that
+length.
+
+   TRACHYNOTUS.--Body more or less elevated, compressed, covered
+   with very small scales. Cleft of the mouth rather small, with
+   short convex snout. Opercles entire. The first dorsal composed
+   of free spines in small number. No finlets. Teeth always small,
+   and generally lost with age.
+
+Ten species are known from the tropical Atlantic and Indo-Pacific; they
+rarely exceed a length of 20 inches. Some of the most common marine
+fishes belong to this genus, for instance _T. ovatus_, which ranges
+over the entire tropical zone.
+
+PAMMELAS (_perciformis_) is allied to the preceding genus; from the
+coast of New York.
+
+  [Illustration: Fig. 198.--Magnified scale of Psettus argenteus.]
+
+   PSETTUS.--Body much compressed and elevated; snout rather short.
+   One dorsal, entirely covered with scales, with seven or eight
+   spines; anal fin with three. Ventrals very small, rudimentary.
+   Teeth villiform; no teeth on the palate. Scales small, ctenoid.
+
+Only three species are known; one, _P. sebæ_, from the west coast of
+Africa, the two others from the Indo-Pacific. _P. argenteus_ is a very
+common fish, attaining to a length of about 10 inches.
+
+  [Illustration: Fig. 199.--Psettus argenteus.]
+
+   PLATAX.--Body much compressed and elevated; snout very short.
+   One dorsal, with the spinous portion nearly entirely hidden, and
+   formed by from three to seven spines; anal with three. Ventrals
+   well developed, with one spine and five rays. Teeth setiform,
+   with an outer series of rather larger teeth, notched at the top;
+   palate toothless. Scales of moderate size or rather small.
+
+These fishes are called “Sea-bats,” from the extraordinary length of
+some portion of their dorsal and anal fins and of their ventrals. These
+long lobes are generally of a deep black colour. In mature and old
+individuals the fin-rays are much shorter than in the young, which have
+been described as distinct species. There are probably not more than
+seven species of “Sea-bats,” if so many, and they all belong to the
+Indian Ocean and Western Pacific, where they are very common.
+
+   ZANCLUS.--Body much compressed and elevated. One dorsal, with
+   seven spines, the third of which is very elongate. No teeth on
+   the palate. Scales minute, velvety.
+
+One species (_Z. cornutus_), which is extremely common in the
+Indo-Pacific. It is easily recognised by its snout, which is produced
+like that of _Chelmon_, and by the broad black bands crossing the
+yellow ground-colour. It attains to a length of eight inches, and
+undergoes during growth similar changes as _Acanthurus_.
+
+   ANOMALOPS.--Body oblong, covered with small, rough scales. Snout
+   very short, convex, with wide cleft of the mouth. Eyes very
+   large; below the eye, in a cavity of the infraorbital ring,
+   there is a glandular phosphorescent organ. Villiform teeth in
+   the jaws and on the palatine bones, none on the vomer. First
+   dorsal fin short, with a few feeble spines connected by membrane.
+
+This genus, of which one species only is known (_A. palpebratus_),
+represents the family of Horse-Mackerels in the depths of the sea; but
+we do not know, at present, at what depth it lives. Only six specimens
+have been obtained hitherto from the vicinity of Amboyna, the Fidji,
+and Paumotu Islands; the largest was twelve inches long.
+
+   CAPROS.--Body compressed and elevated. Mouth very protractile.
+   Scales rather small, spiny. First dorsal with nine spines, anal
+   with three. Ventral fins well developed. Minute teeth in the
+   jaws and on the vomer; none on the palatine bones.
+
+The “Boar-fish” (_C. aper_) is common in the Mediterranean, and not
+rarely found on the south coast of England.
+
+Allied are _Antigonia_ and _Diretmus_, known from a few individuals
+obtained at Madeira and Barbadoes; they are probably fishes which but
+rarely come to the surface.
+
+   EQUULA.--Body more or less compressed, elevated or oblong,
+   covered with small, deciduous, cycloid scales. Mouth very
+   protractile. Minute teeth in the jaws; none on the palate. One
+   dorsal. Formula of the fins: D. 8/1516, A. 3/14, V. 1/5. The
+   lower præopercular margin serrated.
+
+  [Illustration: Fig. 200.--Equula edentula.]
+
+Small species, abundant in the Indo-Pacific, disappearing on the coasts
+of Japan and Australia. Some eighteen species have been described.
+
+_Gazza_ is very similar to _Equula_, but armed with canine teeth in the
+jaws.
+
+Other genera referred to this family are _Lactarius_ (_L. delicatulus_,
+common, and eaten on the East Indian coasts), _Seriolella_, _Paropsis_,
+and _Platystethus_.
+
+
+                        THIRD FAMILY--CYTTIDÆ.
+
+_Body elevated, compressed, covered with small scales, or with
+bucklers, or naked; eye lateral. Teeth conical, small. No bony stay
+for the præoperculum. Dorsal fin composed of two distinct portions.
+Ventrals thoracic. No prominent papilla near the vent. Gill-opening
+wide. More than ten abdominal and more than fourteen caudal
+vertebræ._
+
+The fishes of the “Dory” family are truly marine, and inhabit the
+temperate zone of the Northern and Southern Hemispheres. Some fossils
+from tertiary formations (one from Licata) belong to the genus Zeus.
+
+   ZEUS.--A series of bony plates runs along the base of the dorsal
+   and anal fins; another series on the abdomen. Three or four anal
+   spines.
+
+“John Dorys” are found in the Mediterranean, on the eastern temperate
+shores of the Atlantic, on the coasts of Japan and Australia. Six
+species are known, all of which are highly esteemed for the table. The
+English name given to one of the European species (_Zeus faber_) seems
+to be partly a corruption of the Gascon “Jau,” which signifies cock,
+“Dory” being derived from the French Dorée, so that the entire name
+means Gilt-Cock. Indeed, in some other localities of Southern Europe it
+bears the name of _Gallo_. The same species occurs also on the coasts
+of South Australia and New Zealand. The fishermen of Roman Catholic
+countries hold this fish in special respect, as they recognise in a
+black round spot on its side the mark left by the thumb of St. Peter
+when he took the piece of money from its mouth.
+
+  [Illustration: Fig. 201.--Cyttus australis.]
+
+   CYTTUS.--Body covered with very small scales; no osseous
+   bucklers on any part of the body. Two anal spines; ventral fins
+   composed of one spine and six or eight rays.
+
+Three species are known from Madeira, South Australia, and New Zealand.
+
+
+                      FOURTH FAMILY--STROMATEIDÆ.
+
+_Body more or less oblong and compressed, covered with very small
+scales; eye lateral. Dentition very feeble; œsophagus armed with
+numerous horny, barbed processes. No bony stay for the præoperculum.
+Dorsal fin single, long, without distinct spinous division. More than
+ten abdominal and more than fourteen caudal vertebræ._
+
+This small family consists of strictly marine and partly pelagic
+species referred to two genera, _Stromateus_ and _Centrolophus_.
+The former lacks ventral fins, at least in the adult stage, and is
+represented by about ten species in almost all the tropical and warmer
+seas. _Centrolophus_, hitherto known from two or three European species
+only (of which one occasionally reaches the south coast of England,
+where it is named “Black-fish”), has recently been discovered on the
+coast of Peru, and has probably a much wider range.
+
+
+                      FIFTH FAMILY--CORYPHÆNIDÆ.
+
+_Body compressed; eye lateral. Teeth small, conical, if present;
+œsophagus smooth. No bony stay for the præoperculum. Dorsal fin single,
+long, without distinct spinous division. More than ten abdominal and
+more than fourteen caudal vertebræ._
+
+All the members of this family have pelagic habits. Representatives of
+it have been recognized in some fossil remains: thus _Goniognathus_
+from the Isle of Sheppey, and the living genus _Mene_ (_Gastrocnemus_)
+at Monte Bolca.
+
+   CORYPHÆNA.--Body compressed, rather elongate; adult specimens
+   with a high crest on the top of the head; cleft of the mouth
+   wide. A single dorsal extending from the occiput almost to the
+   caudal, which is deeply forked; no distinct dorsal and anal
+   spines. The ventrals are well developed, and can be received
+   in a groove on the abdomen. Scales very small. Rasp-like teeth
+   in the jaws, on the vomer and the palatine bones. Air-bladder
+   absent.
+
+  [Illustration: Fig. 202.--Dolphin from the Atlantic.]
+
+Generally, though by misapplication of the name, called “Dolphins.”
+About six species are known, each of which is probably distributed
+over all the tropical and sub-tropical seas. Strictly pelagic in their
+habits, they are most powerful swimmers; they congregate in shoals,
+and pursue unceasingly the Flying-Fish, which try to escape their
+enemies by long flying leaps. They attain to a length of six feet,
+and are eagerly caught by sailors on account of their well-flavoured
+flesh. The beauty of their, unfortunately fugitive, colours has ever
+been a subject of admiration. As far as the colours are capable of
+description, those of the common species (_C. hippurus_), which is
+often seen in the Mediterranean, are silvery blue above, with markings
+of a deeper azure, and reflections of pure gold, the lower parts being
+lemon-yellow, marked with pale blue. The pectoral fins are partly lead
+colour, partly yellow; the anal is yellow, the iris of the eye golden.
+These iridescent colours change rapidly whilst the fish is dying, as in
+the Mackerel. The form of the body, and especially of the head, changes
+considerably with age. Very young specimens, from one to six inches
+in length, are abundant in the open sea, and frequently obtained in
+the tow-net. Their body is cylindrical, their head as broad as high,
+and the eye relatively very large, much longer than the snout. As the
+fish grows the body is more compressed, and finally a high crest is
+developed on the head, and the anterior part of the dorsal fin attains
+a height equal to that of the body.
+
+   BRAMA.--Body compressed, and more or less elevated, covered with
+   rather small scales; cleft of the mouth very oblique, with the
+   lower jaw longest. Dorsal and anal fins many-rayed, the former
+   with three or four, the latter with two or three, spines; caudal
+   deeply forked. Ventrals thoracic, with one spine and five rays.
+   The jaws with an outer series of stronger teeth.
+
+Pelagic fishes which, like the allied genus _Taractes_, range over
+almost all the tropical and temperate seas.
+
+   LAMPRIS.--Body compressed and elevated, covered with very small
+   deciduous scales; cleft of the mouth narrow. A single dorsal,
+   without a spinous portion. Ventrals composed of numerous rays.
+   Teeth none.
+
+  [Illustration: Fig. 203.--Lampris luna.]
+
+The “Sun-fish” (_L. luna_) is one of the most beautiful fishes of
+the Atlantic. It attains to the large size of four feet in length, is
+bluish on the back, with round silvery spots, which colour prevails
+on the lower parts; the fins are of a deep scarlet. It is said to be
+excellent eating. It is a pelagic fish, not rare about Madeira, but
+extending far northwards in the Atlantic; it seems to be rarer in the
+Mediterranean. All the specimens hitherto obtained were full-grown
+or nearly so. The skeleton exhibits several peculiarities, viz. an
+extraordinary development and dilatation of the humeral arch, and great
+strength of the numerous and closely-set ribs.
+
+Other Coryphænoid genera are _Pteraclis_, _Schedophilus_, _Diana_,
+_Ausonia_, and _Mene_; all pelagic forms.
+
+
+                        SIXTH FAMILY--NOMEIDÆ.
+
+_Body oblong, more or less compressed, covered with cycloid scales of
+moderate size; eye lateral. No bony stay for the præoperculum. Dorsal
+fin with a distinct spinous portion separated from the soft; sometimes
+finlets; caudal forked. More than ten abdominal, and more than fourteen
+caudal vertebræ._
+
+Marine fishes; pelagic, at least when young.
+
+  [Illustration: Fig. 204.--Gastrochisma melampus.]
+
+   GASTROCHISMA.--Cleft of the mouth wide. Finlets behind the
+   dorsal and anal fins. The ventral fins are exceedingly broad
+   and long, and can be completely concealed in a fold of the
+   abdomen.
+
+_G. melampus_, from the coast of New Zealand; scarce.
+
+   NOMEUS.--Cleft of the mouth narrow. No finlets. The ventral fin
+   is long and broad, attached to the abdomen by a membrane, and
+   can be received in a fissure of the abdomen.
+
+_N. gronovii_ is a common pelagic fish in the Atlantic and Indian
+Oceans; of small size.
+
+Other genera belonging to this family are _Psenes_ and _Cubiceps_.
+
+
+                      SEVENTH FAMILY--SCOMBRIDÆ.
+
+_Body oblong, scarcely compressed, naked or covered with small
+scales; eye lateral. Dentition well developed. No bony stay for the
+præoperculum. Two dorsal fins; generally finlets. Ventrals thoracic,
+with one spine and five rays. More than ten abdominal, and more than
+fourteen caudal vertebræ._
+
+The fishes of the “Mackerel” family are pelagic forms, abundant in all
+the seas of the tropical and temperate zones. They are one of the four
+families of fishes which are the most useful to man, the others being
+the Gadoids, Clupeoids, and Salmonoids. They are fishes of prey, and
+unceasingly active, their power of endurance in swimming being equal
+to the rapidity of their motions. Their muscles receive a greater
+supply of blood-vessels and nerves than in other fishes, and are of a
+red colour, and more like those of birds or mammals. This energy of
+muscular action causes the temperature of their blood to be several
+degrees higher than in other fishes. They wander about in shoals, spawn
+in the open sea, but periodically approach the shore, probably in the
+pursuit of other fishes on which they feed.[43]
+
+_Scombridæ_ are well represented in tertiary formations: in the Eocene
+schists of Glaris two extinct genera, _Palimphyes_ and _Isurus_, have
+been discovered. In Eocene and Miocene formations _Scomber_, _Thynnus_,
+and _Cybium_ are not uncommon.
+
+   SCOMBER.--The first dorsal continuous, with feeble spines; five
+   or six finlets behind the dorsal and anal. Scales very small,
+   and equally covering the whole body. Teeth small. Two short
+   ridges on each side of the caudal fin.
+
+Mackerels proper are found in almost all temperate and tropical seas,
+with the exception of the Atlantic shores of temperate South America,
+where they have not been found hitherto. In Europe, and probably
+also on the coast of England, three species occur: _S. scomber_, the
+common Mackerel, which lacks an air-bladder; _S. pneumatophorus_, a
+more southern species, with an air-bladder; and _S. colias_, like the
+former, but with a somewhat different coloration, and often called
+“Spanish” Mackerel. On the Cape of Good Hope, in Japan, on the coast
+of California, in South Australia, and New Zealand, Mackerels are
+abundant, which are either identical with, or very closely allied
+to, the European species. On the coasts of the United States the
+same species occur which tenant the western parts of the Atlantic.
+Altogether seven species are known.
+
+  [Illustration: Fig. 205.--Thynnus thynnus.]
+
+   THYNNUS.--The first dorsal continuous, with the spines rather
+   feeble; from six to nine finlets behind the dorsal and anal.
+   Scales of the pectoral region crowded, forming a corslet. Teeth
+   rather small. A longitudinal keel on each side of the tail.
+
+The best-known species of this genus is the “Tunny” (_Thynnus
+thynnus_), abundant in the Mediterranean, and ranging to the south
+coast of England and to Tasmania. It is one of the largest fishes of
+the ocean, attaining to a length of 10 feet, and to a weight of more
+than 1000 lbs. The fishery of the Tunny is systematically carried on in
+the Mediterranean, and dates from the most remote antiquity. Its salted
+preparation was esteemed by the Romans under the name of _Saltamentum
+sardicum_. Its flesh is extensively eaten now, fresh as well as
+preserved.
+
+_Thynnus pelamys_, or the “Bonito,” is equally well known, and ranges
+over all the tropical and temperate seas; it eagerly pursues the
+Flying-fish, and affords welcome sport and food to the sailor. In its
+form it resembles the Tunny, but is more slender and rarely above three
+feet long.
+
+Some of the other species are provided with very long pectoral fins,
+and generally called by sailors “Albacore.” They are said to grow to a
+length of six feet; Bennett in his “Whaling Voyage,” vol. ii. p. 278,
+makes the following observations on _Th. germo_, from the Pacific:
+“Ships when cruising slowly in the Pacific Ocean, are usually attended
+by myriads of this fish for many successive months. A few days’ rapid
+sailing is, nevertheless, sufficient to get rid of them, however
+numerous they may be, for they seldom pay more than very transient
+visits to vessels making a quick passage. When the ship is sailing with
+a fresh breeze they swim pertinaciously by her side and take the hook
+greedily, but should she be lying motionless or becalmed they go off
+to some distance in search of prey, and cannot be prevailed upon to
+take the most tempting bait the sailor can devise. It is probably as a
+protection from their chief enemy, the Sword-fish, that they seek the
+society of a ship. I am not aware that the Shark is also their enemy;
+but they seemed to have an instinctive dread of this large fish, and
+when it approached the ship, would follow it in shoals, and annoy it in
+the same manner as the smaller birds may be seen to annoy those of a
+larger and predaceous kind, as the hawk or owl. They are very voracious
+and miscellaneous feeders. Flying-fish, Calmars, and small shoal-fish
+are their most natural food; though they do not refuse the animal
+offal from a ship. Amongst the other food contained in their maw, we
+have found small Ostracions, File-fish, Sucking-fish, Janthina shells,
+and pelagic crabs; in one instance a small Bonita, and in a second a
+Dolphin eight inches long, and a Paper-nautilus shell containing its
+sepia-tenant. It was often amusing to watch an Albacore pursuing a
+Flying-fish, and to mark the precision with which it swam beneath the
+feeble æronaut, keeping him steadily in view, and preparing to seize
+him at the moment of his descent. But this the Flying-fish would often
+elude by instantaneously renewing his leap, and not unfrequently escape
+by extreme agility.”
+
+   PELAMYS.--The first dorsal continuous, with the spines rather
+   feeble; from seven to nine finlets behind the dorsal and
+   anal. Scales of the pectoral region forming a corslet. Teeth
+   moderately strong. A longitudinal keel on each side of the tail.
+
+Five species are known, of which _P. sarda_ is common in the Atlantic
+and Mediterranean.
+
+   AUXIS.--Differing from the preceding two genera in having very
+   small teeth in the jaws only, none on the palate.
+
+_Auxis rochei_ common in the Atlantic, Mediterranean, and Indian
+Ocean.
+
+   CYBIUM.--The first dorsal continuous, with the spines rather
+   feeble; generally more than seven finlets behind the dorsal and
+   anal. Scales rudimentary or absent. Teeth strong; a longitudinal
+   keel on each side of the tail.
+
+Twelve species from the tropical Atlantic and Indian Ocean;
+frequenting more the coast-region than the open sea; attaining to a
+length of four or five feet.
+
+   ELACATE.--Body covered with very small scales; head depressed;
+   cleft of the mouth moderately wide; no keel on the tail. The
+   spinous dorsal is formed by eight small free spines; finlets
+   none. Villiform teeth in the jaws, on the vomer and the palatine
+   bones.
+
+_Elacate nigra_, a coast fish common in the warmer parts of the
+Atlantic and the Indian Ocean.
+
+   ECHENEIS.--The spinous dorsal fin is modified into an adhesive
+   disk, occupying the upper side of the head and neck.
+
+This genus is closely allied to the preceding, from which it differs
+only by the transformation of the spinous dorsal fin into a sucking
+organ. The spines being composed of two halves, each half is bent down
+towards the right and the left, forming a support to a double series of
+transverse lamellæ, rough on their edges, the whole disk being of an
+oval shape and surrounded by a membranous fringe. Each pair of lamellæ
+is formed out of one spine, which, as usual, is supported at the base
+by an interneural spine. By means of this disk the “Sucking-fishes”
+or “Suckers” are enabled to attach themselves to any flat surface,
+a series of vacuums being created by the erection of the usually
+recumbent lamellæ. The adhesion is so strong that the fish can only be
+dislodged with difficulty, unless it is pushed forward by a sliding
+motion. The Suckers attach themselves to sharks, turtles, ships, or any
+other object which serves their purpose. They cannot be regarded as
+parasites, inasmuch as they obtain their food independently of their
+host. Being bad swimmers they allow themselves to be carried about by
+other animals or vessels endowed with a greater power of locomotion.
+They were as well known to the ancients as they are to the modern
+navigators. Aristotle and Aelian mention the Sucker under the name of
+φθεὶρ, or the _Louse_; “In the sea between Cyrene and Egypt there is a
+fish about the Dolphin (_Delphinus_), which they call the Louse; this
+becomes the fattest of all fishes, because it partakes of the plentiful
+supply of food captured by the Dolphin.” Later writers, then, repeat
+a story, the source of which is unknown, viz. that the “Remora” is
+able to arrest vessels in their course, a story which has been handed
+down to our own time. It need not be stated that this is an invention,
+though it cannot be denied that the attachment of one of the larger
+species may retard the progress of a sailing vessel, especially when,
+as is sometimes the case, several individuals accompany the same ship.
+An account of a somewhat ingenious way of catching sleeping turtles by
+means of a Sucking-fish held by a ring fastened round its tail, appears
+to have originated rather from an experiment than from regular practice.
+
+Ten different species are known, of which _Echeneis remora_ and
+_Echeneis naucrates_ are the most common. The former is short and grows
+to a length of eight inches only, the latter is a slender fish, not
+rarely found three feet long. The bulkiest is _Echeneis scutata_, which
+attains to a length of two feet; individuals of that size weighing
+about eight lbs.
+
+The number of pairs of lamellæ varies in the various species, from 12
+to 27. The caudal fin of some of the species undergoes great changes
+with age. In young specimens the middle portion of the fin is produced
+into a long filiform lobe. This lobe becomes gradually shorter, and the
+fin shows a rounded margin in individuals of middle age. When the fish
+approaches the mature state, the upper and lower lobes are produced,
+and the fin becomes subcrescentic or forked.
+
+   [See Günther, “On the History of Echeneis.” Ann. and Mag. Nat.
+   Hist., 1860.]
+
+
+                      EIGHTH FAMILY.--TRACHINIDÆ.
+
+_Body elongate, low, naked or covered with scales. Teeth small,
+conical. No bony stay for the præoperculum. One or two dorsal fins,
+the spinous portion being always shorter and much less developed than
+the soft; the anal similarly developed as the soft dorsal; no finlets.
+Ventrals with one spine and five rays. Gill-opening more or less
+wide. Ten or more than ten abdominal, and more than fourteen caudal
+vertebræ._
+
+Carnivorous coast-fishes of small size, found in every quarter of the
+globe, but scarcely represented in the Arctic zone (_Trichodon_); on
+the other hand, they are rather numerous towards the Antarctic circle.
+All are bad swimmers, generally moving along the bottom in small
+depths. Only one genus (_Bathydraco_) is known from the deep-sea.
+
+A genus which shows the principal characters of this family
+(_Callipteryx_), has been found in the tertiary deposits of Monte
+Bolca; it is scaleless. A second genus, _Trachinopsis_, has been
+recently described by Sauvage from the Upper Tertiary of Lorca in
+Spain; and a third (_Pseudoeleginus_) from the Miocene of Licata.
+
+This family may be subdivided into five groups:--
+
+   1. In the URANOSCOPINA the eyes are on the upper surface of the
+   head, directed upwards; the lateral line is continuous.
+
+   URANOSCOPUS.--Head large, broad, thick, partly covered with bony
+   plates; cleft of the mouth vertical. Scales very small. Two
+   dorsal fins, the first with from three to five spines; ventrals
+   jugular; pectoral rays branched. Villiform teeth in the jaws,
+   on the vomer and palatine bones; no canines. Generally a long
+   filament below and before the tongue. Gill-cover armed.
+
+The position of the eyes on the upper surface of the head, which these
+fishes have in common with many others, is well expressed by the name
+_Uranoscopus_ (Stare-gazer). Their eyes are very small, and can be
+raised or depressed at the will of the fish. They are inactive fishes,
+generally lying hidden at the bottom between stones, watching for their
+prey. The delicate filament attached to the bottom of their mouth, and
+playing in front of it in the current of water which passes through the
+mouth, serves to lure small animals within reach of the fish. Eleven
+species are known from the Indo-Pacific and Atlantic, and one (_U.
+scaber_) from the Mediterranean; they attain rarely a length of twelve
+inches.
+
+   LEPTOSCOPUS.--Form of the head as in _Uranoscopus_, but entirely
+   covered with a thin skin. Scales small, cycloid. One continuous
+   dorsal; ventrals jugular; pectoral rays branched. Villiform
+   teeth in both jaws, on the vomer and palatine bones; canines
+   none. No oral filament. Gill-cover unarmed.
+
+  [Illustration: Fig. 206.--Leptoscopus macropygus.]
+
+_Leptoscopus macropygus_, not rare on the coast of New Zealand.
+
+Other genera of Stare-gazers are _Agnus_ from the Atlantic coasts of
+North America; _Anema_ from the Indian Ocean and New Zealand; and
+_Kathetostoma_ from Australia and New Zealand.
+
+   2. In the TRACHININA the eyes are more or less lateral; the
+   lateral line is continuous; and the intermaxillary without a
+   larger tooth on its posterior portion.
+
+   TRACHINUS.--Cleft of the mouth very oblique; eye lateral, but
+   directed upwards. Scales very small, cycloid. Two dorsal fins,
+   the first short, with six or seven spines; ventrals jugular; the
+   lower pectoral rays simple. Villiform teeth in the jaws, on the
+   vomer and palatine bones. Præorbital and præoperculum armed.
+
+The “Weevers” are common fishes on the European coasts, and but too
+well known to all fishermen; singularly enough they do not extend
+across the Atlantic to the American coast, but reappear on the coast of
+Chili! Wounds by their dorsal and opercular spines are much dreaded,
+being extremely painful, and sometimes causing violent inflammation
+of the wounded part. No special poison-organ has been found in these
+fishes, but there is no doubt that the mucous secretion in the vicinity
+of the spines has poisonous properties. The dorsal spines as well as
+the opercular spine have a deep double groove in which the poisonous
+fluid is lodged, and by which it is inoculated in the punctured wound.
+On the British coasts two species occur, _T. draco_, the Greater
+Weever, attaining to a length of twelve inches, and _T. vipera_, the
+Lesser Weever, which grows only to half that size.
+
+   CHAMPSODON.--Body covered with minute granular scales; lateral
+   lines two, with numerous vertical branches. Cleft of the mouth
+   wide, oblique. Eye lateral, but directed upwards. Two dorsal
+   fins; ventral fins jugular; pectoral rays branched. Teeth in the
+   jaws in a single series, thin, long, of unequal size. Teeth on
+   the vomer, none on the palate. Gill-openings exceedingly wide.
+   Præoperculum with a spine at the angle and a fine serrature on
+   the posterior margin.
+
+_Champsodon vorax_ is not uncommon at small depths off the
+Philippine Islands, Admiralty Islands, and in the Arafura Sea.
+
+   PERCIS.--Body cylindrical, with small ctenoid scales; cleft of
+   the mouth slightly oblique; eye lateral, but directed upwards.
+   Dorsal fins more or less continuous, the spinous with four or
+   five short stiff spines; ventrals a little before the pectorals.
+   Villiform teeth in the jaws, with the addition of canines; teeth
+   on the vomer, none on the palatines. Opercles feebly armed.
+
+Fifteen species; small, but prettily coloured shore-fishes of the
+Indo-Pacific.
+
+   SILLAGO.--Body covered with rather small, ctenoid scales.
+   Cleft of the mouth small, with the upper jaw rather longer;
+   eye lateral, large. Two dorsals, the first with from nine
+   to twelve spines; ventrals thoracic. Villiform teeth in the
+   jaws, and on the vomer, none on the palatine bones. Operculum
+   unarmed; præoperculum serrated. The bones of the head with wide
+   muciferous channels.
+
+Eight species; small, plain-coloured shore-fishes, common in the Indian
+Ocean to the coasts of Australia.
+
+   BOVICHTHYS.--Head broad and thick; cleft of the mouth
+   horizontal, with the upper jaw rather longer; eye lateral, more
+   or less directed upwards. Scales none. Two separate dorsal
+   fins, the first with eight spines; ventrals jugular; the lower
+   pectoral rays simple. Villiform teeth in the jaws, on the vomer
+   and the palatine bones; no canines. Operculum with a strong
+   spine; præorbital and præoperculum not armed.
+
+Three species are known from the South Pacific.
+
+  [Illustration: Fig. 207.--Head of Bovichthys variegatus, from New
+  Zealand.]
+
+   BATHYDRACO.--Body elongate, sub-cylindrical; head depressed,
+   with the snout much elongate, spatulate; mouth wide, horizontal,
+   with the lower jaw prominent; eyes very large, lateral, close
+   together. Scales very small, imbedded in the skin. Lateral line
+   wide, continuous. One dorsal fin; ventrals jugular; the lower
+   pectoral rays branched. Teeth in the jaws in villiform bands;
+   none on the vomer or the palatine bones. Opercles unarmed; ten
+   branchiostegals; the gill-membranes free from the isthmus, and
+   but slightly united in front. Air-bladder none.
+
+A deep-sea fish, found at a depth of 1260 fathoms in the Antarctic
+Ocean (south of Heard Island).
+
+   CHÆNICHTHYS.--Head very large, with the snout spatulate, and
+   with the cleft of the mouth very wide. Eye lateral. Scales none;
+   lateral line sometimes with granulated scutes. Two dorsals, the
+   first with seven spines; ventrals jugular. Jaws with rasp-like
+   teeth; palate toothless.
+
+_Chænichthys rhinoceratus_ from Kerguelen’s Land (see Fig. 108, p.
+291); and _Ch. esox_ from the Straits of Magelhaen.
+
+Other genera belonging to this group are _Aphritis_, _Acanthaphritis_,
+_Eleginus_, _Chænichthys_, and _Chimarrhichthys_ from the South Pacific
+and Antarctic zone; _Cottoperca_ from the west coast of Patagonia;
+_Percophis_ from the coast of Southern Brazil; and _Trichodon_ from the
+coast of Kamtschatka.
+
+   3. In the PINGUIPEDINA the body is covered with small scales;
+   the eye lateral; the lateral line continuous; and the
+   intermaxillary is armed with a larger tooth on its posterior
+   portion, as in many Labroids.
+
+Two genera, _Pinguipes_ and _Latilus_, from various parts of tropical
+and sub-tropical seas, belong to this group.
+
+   4. In the PSEUDOCHROMIDES, the lateral line is interrupted or
+   not continued to the caudal fin; they have one continuous dorsal
+   only.
+
+These fishes are inhabitants of coral reefs or coasts:
+_Opisthognathus_, _Pseudochromis_, _Cichlops_, and _Pseudoplesiops_.
+
+   5. In the NOTOTHENIINA the lateral line is interrupted;
+   and the dorsal fin consists of two separate portions.
+
+They (with others) represent in the Antarctic zone the Cottoids of
+the Northern Hemisphere: they have the same habits as their northern
+analogues. In _Notothenia_, which on the southern extremity of South
+America, in New Zealand, Kerguelen’s Land, etc., is represented by
+about twenty species, the body is covered with ctenoid scales, and the
+bones of the head are unarmed; whilst _Harpagifer_, a small species
+with a similar range as _Notothenia_, has the body naked, and the
+operculum and sub-operculum armed with long and strong spines.
+
+
+                      NINTH FAMILY--MALACANTHIDÆ.
+
+_Body elongate, with very small scales; mouth with thick lips; a
+strong tooth posteriorly on the intermaxillary. Dorsal and anal fins
+very long, the former with a few simple rays anteriorly; ventrals
+thoracic, with one spine and five rays. Gill-opening wide, with the
+gill-membranes united below the throat. Ten abdominal and fourteen
+caudal vertebræ._
+
+One genus only, _Malacanthus_, with three species from tropical
+seas.
+
+
+                       TENTH FAMILY--BATRACHIDÆ.
+
+_Head broad and thick; body elongate, compressed behind; skin naked
+or with small scales. No bony stay for the præoperculum. Teeth conical,
+small or of moderate size. The spinous dorsal consists of two or three
+spines only; the soft and the anal long. Ventrals jugular, with two
+soft rays; pectorals not pediculated. Gill-opening a more or less
+vertical slit before the pectoral, rather narrow._
+
+Carnivorous fishes, of small size, living on the bottom of the sea near
+the coast in the tropical zone, some species advancing into the warmer
+parts of the temperate zones.
+
+   BATRACHUS.--The spinous dorsal is formed by three stout spines.
+   Gill-covers armed with spines. Circumference of the mouth and
+   other parts of the head frequently provided with small skinny
+   tentacles.
+
+Some of the fishes of this genus possess a subcutaneous spacious
+cavity behind the base of the pectoral fin, the inside of which is
+coated with a reticulated mucous membrane. It opens by a foramen in
+the upper part of the axil.--This apparatus is the same which is found
+in many Siluroid fishes, and which has been noticed above, p. 192.
+There cannot be any doubt that it is a secretory organ, but whether
+the secretion has any poisonous properties, as in the Siluroids, or
+as in _Thalassophryne_, has not been determined. No instance of
+poisonous wounds having been inflicted by these fishes is on record.
+Twelve species are known, the distribution of which coincides with that
+of the family; one very fine species, _B. didactylus_, occurs in
+the Mediterranean.
+
+   THALASSOPHRYNE.--The spinous dorsal is formed by two spines
+   only, each of which is hollow, like the opercular spine, and
+   conveys the contents of a poison-bag situated at its base.
+   Canine teeth none.
+
+  [Illustration: Fig. 208.--Thalassophryne reticulata.]
+
+Two species are known from the Atlantic and Pacific coasts of Central
+America. The poison-apparatus is more perfectly developed than any
+other known at present in the class of fishes; it has been described
+above, p. 192. The species figured, _Th. reticulata_, is not uncommon
+at Panama, and attains to a length of fifteen inches.
+
+   PORICHTHYS.--Two small dorsal spines; a canine tooth on each
+   side of the vomer.
+
+Two species, from the Atlantic and Pacific sides of Central and South
+America.
+
+
+                    ELEVENTH FAMILY--PSYCHROLUTIDÆ.
+
+_Body rather elongate, naked; head broad. Spinous dorsal separate or
+absent. Ventral fins close together, thoracic, composed of a few rays.
+Teeth small. Three gills and a half; pseudobranchiæ well developed;
+gill-openings of moderate width, the gill-membranes being attached to
+the isthmus._
+
+Of this family only two representatives are known, viz. _Psychrolutes
+paradoxus_, from Vancouver’s Islands, without first dorsal fin; and
+_Neophrynichthys latus_, from New Zealand, with two dorsal fins. Both
+are very scarce marine fishes.
+
+
+                      TWELFTH FAMILY--PEDICULATI.
+
+_Head and anterior part of the body very large, without scales. No
+bony stay for the præoperculum. Teeth villiform or rasp-like. The
+spinous dorsal is advanced forwards, composed of a few more or less
+isolated spines, often transformed into tentacles; or entirely absent.
+Ventral fins jugular, with four or five soft rays, sometimes absent.
+The carpal bones are prolonged, forming a sort of arm, terminating in
+the pectoral. Gill-opening reduced to a small foramen, situated in or
+near the axil. Gills two and a half, or three, or three and a half;
+pseudobranchiæ generally absent._
+
+This family contains a larger number of bizarre forms than any other;
+and there is, perhaps, none in which the singular organisation of the
+fish is more distinctly seen to be in consonance with its habits.
+Pediculates are found in all seas. The habits of all are equally
+sluggish and inactive; they are very bad swimmers; those found near the
+coasts lie on the bottom of the sea, holding on with their arm-like
+pectoral fins by seaweed or stones, between which they are hidden;
+those of pelagic habits attach themselves to floating seaweed or
+other objects, and are at the mercy of wind and current. A large
+proportion of the genera, therefore, have gradually found their way to
+the greatest depths of the ocean; retaining all the characteristics of
+their surface-ancestors, but assuming the modifications by which they
+are enabled to live in abyssal depths.
+
+   LOPHIUS.--Head exceedingly large, broad, depressed, with the
+   eyes on its upper surface; cleft of the mouth very wide. Jaws
+   and palate armed with rasp-like depressible teeth of unequal
+   size. Body naked; bones of the head armed with numerous spines.
+   The three anterior dorsal spines are isolated, situated on the
+   head, and modified into long tentacles; the three following
+   spines form a continuous fin; the soft dorsal and anal short.
+   Gills three. Young individuals have the tentacles beset with
+   lappets, and most of the fin-rays prolonged into filaments.
+
+These fishes are well known under the names “Fishing-Frog,”
+“Frog-fishes,” “Anglers,” or “Sea-devils.” They are coast-fishes,
+living at very small depths. Four species are known: the British
+species (_L. piscatorius_) found all round the coasts of Europe
+and Western North America, and on the Cape of Good Hope; a second
+(Mediterranean) species, _L. budegassa_; _L. setigerus_ from China and
+Japan; and _L. naresii_ from the Admiralty Islands.
+
+  [Illustration: Fig. 209.--Lophius piscatorius.]
+
+  [Illustration: Fig. 210.--A young Fishing-Frog.]
+
+The habits of all these species are identical. The wide mouth
+extends all round the anterior circumference of the head, and both
+jaws are armed with bands of long pointed teeth, which are inclined
+inwards, and can be depressed so as to offer no impediment to an
+object gliding towards the stomach, but prevent its escape from the
+mouth. The pectoral and ventral fins are so articulated as to perform
+the functions of teeth, the fish being enabled to move, or rather to
+walk, on the bottom of the sea, where it generally hides itself in
+the sand, or amongst seaweed. All round its head, and also along the
+body, the skin bears fringed appendages, resembling short fronds of
+seaweed; a structure which, combined with the extraordinary faculty of
+assimilating the colours of the body to its surroundings, assists this
+fish greatly in concealing itself in places which it selects on account
+of the abundance of prey. To render the organisation of these creatures
+perfect in relation to their wants, they are provided with three long
+filaments inserted along the middle of the head, which are, in fact,
+the detached and modified three first spines of the anterior dorsal
+fin. The filaments most important in the economy of the fishing-frogs
+is the first, which is the longest, terminates in a lappet, and is
+movable in every direction. There is no doubt that the Fishing-frog,
+like many other fish provided with similar appendages, plays with this
+filament as with a bait, attracting fishes, which, when sufficiently
+near, are ingulfed by the simple act of the Fishing-frog opening its
+gape. Its stomach is distensible in an extraordinary degree, and not
+rarely fishes have been taken out of it quite as large and heavy as
+their destroyer. The British species grows to a length of more than
+five feet; specimens of three feet are common. Baird records that the
+spawn of the same species has been observed as a floating sheet of
+mucus, of from some 60 to 100 square feet.
+
+   CERATIAS.--Head and body much compressed and elevated; cleft
+   of the mouth wide, subvertical. Eyes very small. Teeth in the
+   jaws rasp-like, depressible; palate toothless. Skin covered
+   with numerous prickles. The spinous dorsal is reduced to two
+   long isolated spines, the first on the middle of the head, the
+   second on the back. The soft dorsal and anal short; caudal very
+   long. Ventrals none; pectorals very short. Two and a half gills.
+   Skeleton soft and fibrous.
+
+_Ceratias holbölli_, a deep-sea fish; only a few examples have been
+found near the coast of Greenland, and from the mid-Atlantic; the
+latter at a depth of 2400 fathoms. Deep black.
+
+   HIMANTOLOPHUS.--Head and body compressed and elevated; cleft
+   of the mouth wide, oblique. Eyes very small. Teeth of the jaws
+   rasp-like, depressible; palate toothless. Skin with scattered
+   conical tubercles. The spinous dorsal is reduced to a single
+   tentacle on the head. The soft dorsal, anal, caudal, and
+   pectoral short. Ventrals none. Three and a half gills. Skeleton
+   soft and fibrous.
+
+This is another deep-sea form, hitherto found in very few examples in
+the Arctic and Mid-Atlantic Oceans. The single tentacle is beset with
+many long filaments at its extremity, thus answering the same purpose
+which is attained by a greater number of tentacles. Deep black.
+
+   MELANOCETUS.--Head and body compressed; head very large; cleft
+   of the mouth exceedingly wide, vertical. Eyes very small. Teeth
+   of the jaws and vomer rasp-like, depressible. Skin smooth. The
+   spinous dorsal is reduced to a single filament placed on the
+   head. The soft dorsal and anal short. Ventrals none.
+
+  [Illustration: Fig. 211.--Melanocetus johnsonii.]
+
+Two species are known from the Atlantic: _M. bispinossus_ and _M.
+johnsonii_, obtained at depths of from 360 to 1800 fathoms. The
+specimen figured was not quite four inches long, and contained in
+its stomach, rolled up spirally into a ball, a Scopeline fish which
+measured 7½ inches in length and one inch in depth.
+
+   ONEIRODES.--A deep-sea fish from the Arctic Ocean, differing
+   from the preceding in possessing a second isolated dorsal ray on
+   the back.
+
+   ANTENNARIUS.--Head very large, high, compressed; cleft of the
+   mouth vertical or subvertical, of moderate width. Jaws and
+   palate armed with rasp-like teeth. Eye small. Body naked or
+   covered with minute spines; generally with tentacles. The
+   spinous dorsal is reduced to three isolated spines, the anterior
+   of which is modified into a tentacle, situated above the snout.
+   The soft dorsal of moderate length; anal short. Ventrals present.
+
+The fishes of this genus are pelagic, frequently met with in mid-ocean
+between the tropics, especially in parts of the sea with floating
+vegetation; not rarely individuals are found far from their native
+latitudes, carried by currents to the coasts of Norway and New Zealand.
+Their power of swimming is most imperfect. When near the coast they
+conceal themselves between corals, stones, or fucus, holding on to the
+ground by means of their arm-like pectoral fins. Their coloration is so
+similar to their surroundings that it is hardly possible to distinguish
+the fish from a stone or coral overgrown with vegetation. Their way of
+attracting and seizing their prey is evidently the same as in the other
+fishes of this family. The extraordinary range of some of the species
+which inhabit the Atlantic as well as the Indo-Pacific Oceans, is the
+consequence of their habit of attaching themselves to floating objects.
+Almost all the species are highly coloured, but the pattern of the
+various colours varies exceedingly. These fishes do not attain to any
+considerable size, and probably never exceed a length of ten inches. A
+great number of species have been distinguished by ichthyologists, but
+probably not more than twenty are known at present. The species figured
+on p. 295 (_A. caudomaculatus_) is common in the Red Sea, and
+probably occurs in other parts of the Indian Ocean.
+
+_Brachionichthys_ and _Saccarius_ are allied genera from South
+Australia, Tasmania, and New Zealand.
+
+   CHAUNAX.--Head very large, depressed; cleft of the mouth wide,
+   subvertical; eye small; rasp-like teeth in the jaws and palate.
+   Skin covered with minute spines. The spinous dorsal is reduced
+   to a small tentacle above the snout; the soft dorsal of moderate
+   length; anal short; ventrals present.
+
+A deep-sea fish (_Ch. pictus_), of uniform pink colour; hitherto
+found near Madeira and the Fidji Islands, at a depth of 215 fathoms.
+
+   MALTHE.--Anterior portion of the body very broad and depressed.
+   The anterior part of the snout is produced into a more or less
+   prominent process, beneath which there is a tentacle retractile
+   into a cavity. Jaws and palate with villiform teeth. Skin with
+   numerous conical protuberances. Soft dorsal fin and anal very
+   short. Gill-opening superiorly in the axil; gills two and a half.
+
+Although the rostral tentacle is situated at the lower side of the
+projection of the snout, it must be regarded as the homologue of
+a dorsal spine. In some of the preceding genera, _Oneirodes_ and
+_Chaunax_, the first dorsal spine is so far advanced on the snout as
+to come into connection with the intermaxillary processes; and the
+position of the rostral tentacle in _Malthe_ is only a still more
+advanced step towards the same special purpose for which the first
+dorsal spine is used in this family, viz. for the purpose of obtaining
+food. In _Malthe_ it is obviously an organ of touch. This genus belongs
+to the American shores of the Atlantic; _M. vespertilio_ being a
+tropical, _M. cubifrons_ a northern species.
+
+   HALIEUTÆA.--Head exceedingly large, depressed, nearly circular
+   in its circumference. Cleft of the mouth wide, horizontal.
+   Jaws with small rasp-like teeth; palate smooth. Forehead
+   with a transverse bony bridge, beneath which is a tentacle
+   (rostral spine) retractile into a cavity. Body and head covered
+   with small stellate spines. Soft dorsal and anal very short.
+   Gill-opening superiorly in the axil; gills two and a half.
+
+A coast-fish (_H. stellata_) from China and Japan. Frequently found dry
+in Chinese insect-boxes.
+
+This genus appears to be represented in the Atlantic Ocean by
+_Halieutichthys_ from Cuba, and by _Dibranchus_, dredged at a depth of
+360 fathoms off the coast of West Africa; the latter genus possesses
+two gills only. Another genus, covered with large scattered tubercles,
+_Aegæonichthys_, has recently been described from New Zealand.
+
+
+                      THIRTEENTH FAMILY--COTTIDÆ.
+
+_Form of the body oblong, sub-cylindrical. Cleft of the mouth lateral.
+Dentition feeble, generally in villiform bands. Some bones of the head
+are armed; and a bony stay connects the præopercular spine with the
+infraorbital ring. Two dorsal fins (rarely one), the spinous being less
+developed than the soft and than the anal. Ventrals thoracic, with five
+or less soft rays._
+
+The fishes of this family are of small size, bad swimmers, and
+generally living on the bottom, near the coasts, of almost all the
+arctic, temperate, and tropical seas. Only a few live in fresh water.
+They prefer shallow to deep water; and there is only one instance
+known of a member of this family living at a great depth, viz. _Cottus
+bathybius_ from the Japanese sea, which is stated to have been dredged
+in a depth of 565 fathoms. Fossil representatives are few in number:
+two or three species of _Trigla_; others, although having a general
+resemblance to the genus _Cottus_, were covered with ctenoid scales,
+and therefore are referred to a distinct genus, _Lepidocottus_; they
+are from tertiary formations.
+
+   COTTUS.--Head broad, depressed, rounded in front; body
+   sub-cylindrical, compressed posteriorly. Scaleless; lateral line
+   present. Pectoral rounded, with some or all the rays simple.
+   Jaws and vomer with villiform teeth; palatine teeth none.
+
+The “Bull-heads” or “Miller’s Thumbs” are small fishes from the
+shores and fresh waters of the northern temperate zone. Some forty
+species are known; the greater number live in the northern half of
+the temperate zone. On the shore, as well as in rivers, they prefer
+rocky or stony to muddy ground, lying concealed between the stones,
+and watching for their prey, which consists of small crustaceans and
+other aquatic animals. The common British Miller’s Thumb (_C. gobio_)
+is found in almost all suitable fresh waters of Northern and Central
+Europe, especially in small streams, and extends into Northern Asia.
+Other freshwater species abound in North America and Northern Asia.
+_Cottus scorpius_ and _C. bubalis_, the common European marine species,
+range across the Atlantic to the American coasts. The male is said
+to construct a nest, for the reception of the spawn, of seaweeds and
+stones, and to anxiously watch and defend his offspring. The spine at
+the angle of the præoperculum, which is simple in the majority of the
+freshwater species, is frequently armed with accessory processes, and
+antler-like, in marine.
+
+   CANTRIDERMICHTHYS differs from _Cottus_ in having teeth on the
+   palatine bones.
+
+Eleven species are known, distributed like _Cottus_, but absent in
+Europe and North-western Asia.
+
+   ICELUS.--Head large, armed at the gill-covers and on the neck;
+   body with a dorsal series of bony plates from the neck to
+   the base of the caudal; lateral line with osseous tubercles;
+   scattered scales on the sides and abdomen. Ventrals thoracic,
+   with less than five rays. No pectoral filaments. Villiform teeth
+   in the jaws, on the vomer and palatine bones.
+
+Represents Cottus in the far north; _I. hamatus_ is common in
+Spitzbergen and Greenland, and has been found in abundance in lat. 81°
+44’.
+
+   PLATYCEPHALUS.--Head broad, much depressed, more or less armed
+   with spines; body depressed behind the head, sub-cylindrical
+   towards the tail, covered with ctenoid scales. Two dorsal fins;
+   the first spine isolated from the others. Ventrals thoracic,
+   but rather remote from the base of the pectorals. Villiform
+   teeth in the jaws, on the vomer and palatine bones.
+
+  [Illustration: Fig. 212.--Platycephalus cirrhonasus, from Port
+  Jackson.]
+
+About forty species are known, of which some attain a length of two
+feet. This genus represents in the tropical Indian Ocean the _Cotti_
+of the Arctic, and the _Nototheniæ_ of the Antarctic zone. Like these,
+they live on the bottom in shallow water, hidden in the sand, the
+colours of which are assimilated by those of their body. Therefore,
+they are very scarce near coral islands which are surrounded by great
+depths; whilst the number of species is rather considerable on many
+points of the shelving Australian coasts. Their long and strong ventral
+fins are of great use to them in locomotion. _P. insidiator_ is one of
+the most common Indian and Australian fishes, and readily recognised by
+two oblique black bands on the upper and lower caudal lobes.
+
+  [Illustration: Fig. 213.--Scale from the lateral line of the same
+  fish.]
+
+   HOPLICHTHYS, similar to _Platycephalus_, but with the back and
+   sides of the body covered with bony spiny plates. No separate
+   dorsal spine.
+
+One species, _H. langsdorffii_, is common on the coast of Japan,
+and frequently placed dry by the Chinese into their insect-boxes.
+
+   TRIGLA.--Head parallelopiped, with the upper surface and the
+   sides entirely bony, the enlarged infraorbital covering the
+   cheek.
+
+Two dorsal fins. Three free pectoral rays. Villiform teeth. Air-bladder
+generally with lateral muscles, often divided into two lateral halves.
+The species may be referred to three groups:--
+
+   1. Palatine teeth none; scales exceedingly small, except those
+   of the lateral line: _Trigla_.
+
+   2. Palatine teeth none; scales of moderate size: _Lepidotrigla_.
+
+   3. Palatine teeth present: _Prionotus_.
+
+  [Illustration: Fig. 214.--Trigla pleuracanthica.]
+
+  [Illustration: Fig. 215.--Scute of the lateral line of the same
+  fish.]
+
+About forty species of “Gurnards” are known from tropical and temperate
+zones. They are too well known to need detailed description; one of
+their principal characteristics is the three free finger-like pectoral
+appendages, which serve as organs of locomotion as well as touch, and
+which are supplied with strong nerves, as noticed above (pp. 108 and
+120). The fins are frequently beautifully ornamented, especially the
+inner side of the long and broad pectorals, which is most exposed to
+the light when the fish is floating on the surface of the water, with
+pectorals spread out like wings. The grunting noise made by Gurnards
+when taken out of the water is caused by the escape of gas from the
+air-bladder through the open pneumatic duct. Gurnards are generally
+used as food; seven species occur on the British coast: the Red Gurnard
+(_T. pini_), the Streaked Gurnard (_T. lineata_), the Sapphirine
+Gurnard (_T. hirundo_), the Grey Gurnard (_T. gurnardus_), Bloch’s
+Gurnard (_T. cuculus_), the Piper (_T. lyra_), and the Long-finned
+Gurnard (_T. obscura_ or _T. lucerna_). Singularly, the European
+species cross the Atlantic but rarely, the American species belonging
+chiefly to the division _Prionotus_.
+
+Several other genera belong to this family; for completeness’ sake they
+are mentioned here, viz. _Bunocottus_ from Cape Horn; _Rhamphocottus_,
+_Triglops_ from Arctic North America; _Podabrus_, _Blepsias_,
+_Nautichthys_, _Scorpænichthys_, _Hemilepidotus_, _Artedius_, from the
+North Pacific; _Ptyonotus_, from Lake Ontario; _Polycaulus_ from Indian
+Seas; Bembras from the Japanese Sea.
+
+
+                    FOURTEENTH FAMILY--CATAPHRACTI.
+
+_Form of the body elongate, sub-cylindrical. Dentition feeble. Body
+completely cuirassed with osseous keeled scales or plates. A bony stay
+connects the angle of the præoperculum with the infraorbital ring.
+Ventrals thoracic._
+
+Marine fishes, and partly pelagic. _Petalopteryx_, from the chalk of
+Mount Lebanon, is supposed to have a resemblance to _Dactylopterus_.
+
+   AGONUS.--Head and body angular, covered with bony plates. Two
+   dorsal fins; no pectoral appendages. Small teeth in the jaws.
+
+Small fishes, from the northern parts of the temperate zone and
+extending into the Arctic Ocean; the genus reappears in the Southern
+Hemisphere on the coast of Chile. Of the eleven species known, one
+(_A. cataphractus_) is not uncommon on the coast of Great Britain.
+
+   ASPIDOPHOROIDES, from Greenland, has a very similar form of the
+   body, but possesses one short dorsal fin only.
+
+   SIPHAGONUS.--With the snout produced into a long tube like a
+   Syngnathus; chin prominent, with a barbel.
+
+From Behring’s Strait and Japan.
+
+   PERISTETHUS.--Head parallelopiped, with the upper surface and
+   the sides entirely bony; each præorbital prolonged into a long
+   flat process, projecting beyond the snout. Body cuirassed with
+   large bony plates. One continuous dorsal, or two dorsals, of
+   which the second is the more developed. Two free pectoral
+   appendages. Teeth none; lower jaw with barbels.
+
+Singularly shaped fishes, of rather small size, from the Mediterranean,
+the warmer parts of the Atlantic, and the Indian Ocean; of the ten
+species known one species only has been found in the Pacific, near the
+Sandwich Islands. The European species is _P. cataphractum_. They are
+not common, and probably inhabit greater depths than the Gurnards, with
+which they have much in common as regards their habits.
+
+  [Illustration: Fig. 216.--Dactylopterus volitans.]
+
+   DACTYLOPTERUS.--Head parallelopiped, with the upper surface and
+   the sides entirely bony; scapula and angle of the præoperculum
+   produced into long spines. Body with strongly keeled scales of
+   moderate size; lateral line none. Two dorsal fins, the second
+   not much longer than the first; pectoral very long, an organ of
+   flying, with the upper portion detached and shorter. Granular
+   teeth in the jaws; none on the palate. Air-bladder divided into
+   two lateral halves, each with a larger muscle.
+
+Of “Flying Gurnards” three species only are known, which are very
+abundant in the Mediterranean, the tropical Atlantic, and Indo-Pacific.
+They, and the Flying Herrings (Exocoetus), are the only fishes which
+are enabled by their long pectoral fins to take flying leaps out of the
+water, and deserve the name of “Flying-Fishes.” They are much heavier,
+and attain to a larger size, than the Exocoeti, specimens of eighteen
+inches in length not being scarce. When young, their pectorals are much
+shorter, and, consequently, they are unable to raise themselves out of
+the water (_Cephalacanthus_).
+
+The vertebral column shows a singular coalescence of the anterior
+vertebræ, which form a simple tube, as in _Fistularia_.
+
+       *       *       *       *       *
+
+WE insert here as an appendix to this division the small family of
+_Pegasidæ_, the natural affinities of which are not yet clearly
+understood, but which resembles in some of its characters the
+_Cataphracti_.
+
+
+                      FIFTEENTH FAMILY--PEGASIDÆ.
+
+_Body entirely covered with bony plates, anchylosed on the trunk
+and movable on the tail. Barbels none. The margin of the upper jaw is
+formed by the intermaxillaries and their cutaneous prolongation, which
+extends downwards to the extremity of the maxillaries. Gill-cover
+formed by a large plate, homologous to the operculum, præoperculum,
+and sub-operculum; interoperculum a long fine bone, hidden below the
+gill-plate. One rudimentary branchiostegal. The gill-plate is united
+with the isthmus by a narrow membrane; gill-openings narrow, in front
+of the base of the pectoral fin. Gills four, lamellated. Pseudobranchiæ
+and air-bladder absent. One short dorsal and anal fin, opposite to each
+other. Ventral fin present. Ovarian sacs closed._
+
+One genus only is known, _Pegasus_. Its pectoral fins are broad,
+horizontal, long, composed of simple rays, some of which are sometimes
+spinous. Ventral fins one- or two-rayed. Upper part of the snout
+produced into a shorter or longer process. Mouth inferior, toothless.
+Suborbital ring well developed, forming a suture with the gill-cover.
+Vertebræ in small number, thin; no ribs. Four species are known, two
+of which are of a shorter, and the two others of a longer form. The
+former are _P. draconis_, common in the Indian Ocean, and _P. volans_,
+which is frequently stuck by the Chinese into the insect-boxes which
+they manufacture for sale. The two elongate species, _P. natans_ and
+_P. lancifer_, are from the Chinese and Australian coasts. They are all
+very small fishes, probably living on sandy shoal places near the coast.
+
+  [Illustration: Fig. 217.--Pegasus natans.]
+
+
+             NINTH DIVISION--ACANTHOPTERYGII GOBIIFORMES.
+
+_The spinous dorsal, or spinous portion of the dorsal is always
+present, short, either composed of flexible spines, or much less
+developed than the soft; the soft dorsal and anal of equal extent.
+No bony stay for the angle of the præoperculum. Ventrals thoracic or
+jugular, if present, composed of one spine and five, rarely four, soft
+rays. A prominent anal papilla._
+
+Shore-fishes, mostly exclusively marine, but some entering and living
+in fresh waters.
+
+
+                       FIRST FAMILY--DISCOBOLI.
+
+_Body thick or oblong, naked or tubercular. Teeth small. Ventral
+fins with one spine and five rays, all being rudimentary and forming
+the osseous support of a round disk, which is surrounded by a cutaneous
+fringe. Gill-openings narrow, the gill-membranes being attached to the
+isthmus._
+
+Carnivorous fishes, living at the bottom of the shores of northern
+seas. By their ventral disk they are enabled to attach themselves very
+firmly to rocks.
+
+   CYCLOPTERUS.--Body thick, short, covered with a viscous,
+   tubercular skin. Head large, snout short. Villiform teeth in the
+   jaws, none on the palate. Skeleton soft, with but little earthy
+   matter.
+
+  [Illustration: Fig. 218.--Cyclopterus lumpus. _a_, Ventral
+  disk.]
+
+Three species of “Lump-suckers” are known from the northern temperate
+and the arctic zones. The common North European and North American
+species, _C. lumpus_, is known also by the names of “Cock- and
+Hen-Paddle.” It attains to a length of twenty-four inches, but
+generally is much smaller. It is difficult to remove it from any object
+to which it once has attached itself by means of its sucking-disk. Its
+skin is so thick as to more or less entirely conceal the first dorsal
+fin; it is covered with rough tubercles, the larger ones being arranged
+in four series along each side of the body. In young specimens these
+tubercles are absent. The arctic species, _C. spinosus_, has large
+conical plates on the head and body, each plate with a spine in the
+centre. Also of this species the young are naked, the plates making
+only gradually their appearance, in the form of groups of tubercles.
+Their development is irregular, as young specimens of the same size may
+be entirely naked or tubercular. This species ranges beyond the 81°
+lat. N.
+
+  [Illustration: Fig. 219.--Young of Cyclopterus spinosus, from the
+  Arctic Ocean, natural size.]
+
+   LIPARIS.--Body sub-cylindrical, enveloped in a more or less
+   loose naked skin; head broad, obtuse. The infraorbital bone is
+   styliform posteriorly, extending backwards to the margin of
+   the præoperculum. One dorsal fin, with feeble flexible rays.
+   Villiform teeth in the jaws, none on the palate.
+
+Small fishes from the northern coasts of the temperate zone, ranging
+beyond the arctic circle. Eight species are known, of which two (_L.
+lineatus_ and _L. montagui_) occur on the British coasts.
+
+
+                        SECOND FAMILY--GOBIIDÆ.
+
+_Body elongate, naked or scaly. Teeth generally small, sometimes
+with canines. The spinous dorsal fin, or portion of the dorsal fin, is
+the less developed, and composed of flexible spines; anal similarly
+developed as the soft dorsal. Sometimes the ventrals are united into
+a disk. Gill-opening more or less narrow, the gill-membranes being
+attached to the isthmus._
+
+Small carnivorous littoral fishes, many of which have become
+acclimatised in fresh water. They are very abundant with regard to
+species as well as individuals, and found on or near the coasts of all
+temperate and tropical regions. Geologically they appear first in the
+chalk.
+
+   GOBIUS.--Body scaly. Two dorsal fins, the anterior generally
+   with six flexible spines. Ventral fins united, forming a disk
+   which is not attached to the abdomen. Gill-opening vertical,
+   moderately wide.
+
+  [Illustration: Fig. 220.--Gobius lentiginosus, from New Zealand.]
+
+The “Gobies” are distributed over all temperate and tropical coasts,
+and abundant, especially on the latter. Nearly three hundred species
+have been described. They live especially on rocky coasts, attaching
+themselves firmly with their ventrals to a rock in almost any position,
+and thus withstanding the force of the waves. Many of the species seem
+to delight in darting from place to place in the rush of water which
+breaks upon the shore. Others live in quiet brackish water, and not
+a few have become entirely acclimatised in fresh water, especially
+lakes. The males of some species construct nests for the eggs, which
+they jealously watch, and defend even for some time after the young are
+hatched. Several species are found on the British coast: _G. niger_,
+_paganellus_, _auratus_, _minutus_, _ruthensparri_. Fossil species of
+this genus have been found at Monte Bolca.
+
+A very small Goby, _Latrunculus pellucidus_, common in some localities
+of the British Islands and other parts of Europe, is distinguished by
+its transparent body, wide mouth, and uniserial dentition. According
+to R. Collett it offers some very remarkable peculiarities. It lives
+one year only, being the first instance of an _annual vertebrate_. It
+spawns in June and July, the eggs are hatched in August, and the fishes
+attain their full growth in the months from October to December. In
+this stage the sexes are quite alike, both having very small teeth
+and feeble jaws. In April the males lose the small teeth, which are
+replaced by very long and strong teeth, the jaws themselves becoming
+stronger. The teeth of the females remain unchanged. In July and August
+all the adults die off, and in September only the fry are to be found.
+
+There are several other genera, closely allied to Gobius, as
+_Euctenogobius_, _Lophiogobius_, _Doliichthys_, _Apocryptes_,
+_Evorthodus_, _Gobiosoma_ and _Gobiodon_ (with scaleless body)
+_Triænophorichthys_.
+
+   SICYDIUM.--Body covered with ctenoid scales of rather small
+   size. Cleft of the mouth nearly horizontal, with the upper jaw
+   prominent; lips very thick; the lower lip generally with a
+   series of minute horny teeth. A series of numerous small teeth
+   in upper jaw, implanted in the gum, and generally movable;
+   the lower jaw with a series of conical widely-set teeth. Two
+   dorsal fins, the anterior with six flexible spines. Ventral fins
+   united, and forming a short disk, more or less adherent to the
+   abdomen.
+
+Small freshwater fishes inhabiting the rivers and rivulets of the
+islands of the tropical Indo-Pacific. About twelve species are known;
+one occurs in the West Indies. _Lentipes_ from the Sandwich Islands is
+allied to _Sicydium_.
+
+   PERIOPHTHALMUS.--Body covered with ctenoid scales of small or
+   moderate size. Cleft of the mouth nearly horizontal, with the
+   upper jaw somewhat longer. Eyes very close together, immediately
+   below the upper profile, prominent, but retractile, with a
+   well-developed outer eyelid. Teeth conical, vertical in both
+   jaws. Two dorsal fins, the anterior with flexible spines; caudal
+   fin with the lower margin oblique; base of the pectoral fin
+   free, with strong muscles. Ventral fins more or less coalesced.
+   Gill-openings narrow.
+
+The fishes of this genus, and the closely-allied _Boleophthalmus_,
+are exceedingly common on the coasts of the tropical Indo-Pacific,
+especially on parts covered with mud or fucus. During ebb they leave
+the water and hunt for small crustaceans, and other small animals
+disporting themselves on the ground which is left uncovered by the
+receding water. With the aid of their strong pectoral and ventral fins
+and their tail, they hop freely over the ground, and escape danger
+by rapid leaps. The peculiar construction of their eyes, which are
+very movable, and can be thrust far out of their sockets, enables
+them to see in the air as well as in the water; when the eyes are
+retracted they are protected by a membranous eyelid. These fishes
+are absent in the eastern parts of the Pacific and on the American
+side of the Atlantic; but singularly enough one species reappears
+on the West African coast. About seven species are known (including
+_Boleophthalmus_), _P. koelreuteri_ being one of the most common fishes
+of the Indian Ocean.
+
+  [Illustration: Fig. 221.--Periophthalmus koelreuteri.]
+
+   ELEOTRIS.--Body scaly; eyes of moderate size, lateral, not
+   prominent. Teeth small. Two dorsal fins, the anterior generally
+   with six spines. Ventrals not united, though close together,
+   with one spine and five rays.
+
+About sixty species are known from the tropics, only a few extending
+into the temperate zone. As regards form, they repeat almost all the
+modifications observed among the Gobies, from which they differ only
+in having the ventral fins non-coalescent. On the whole they are
+somewhat larger than the Gobies, and rather freshwater than marine
+species, some of them being abundant in the rivulets of the islands of
+the Indo-Pacific and Atlantic. Others have even penetrated into the
+inland-waters of the African continent.
+
+   TRYPAUCHEN.--Body elongate, covered with minute scales;
+   head compressed, with a deep cavity on each side, above the
+   operculum. Teeth small, in a band. One dorsal, the spinous
+   portion composed of six spines; dorsal and anal fins continuous
+   with the caudal, ventral fins united.
+
+Small fishes of singular aspect, from the East Indian coasts. Three
+species, of which _T. vagina_ is common.
+
+   CALLIONYMUS.--Head and anterior part of the body depressed,
+   the rest cylindrical, naked. Snout pointed, with the cleft
+   of the mouth narrow, horizontal, and with the upper jaw very
+   protractile. Eyes rather large, more or less directed upwards.
+   Teeth very small, palate smooth. A strong spine at the angle of
+   the præoperculum. Two dorsal fins, the anterior with three or
+   four flexible spines; ventrals five-rayed, widely apart from
+   each other. Gill-openings very narrow, generally reduced to a
+   foramen on the upper side of the operculum.
+
+The “Dragonets” are small, and generally beautifully coloured marine
+fishes, inhabitants of the coasts of the temperate zone of the
+Old World; the minority of species live in tropical parts of the
+Indo-Pacific; and these seem to descend to somewhat greater depths
+than the littoral species of the northern hemisphere. Secondary sexual
+characters are developed in almost all the species, the mature males
+having the fin-rays prolonged into filaments, and the fin-membranes
+brightly ornamented. On the British coast one species (_C. draco_) is
+very common, and locally called “Skulpin.” About thirty species are
+known, many of which have the præopercular spine armed with processes
+or barbs. _Vulsus_ is allied to _Callionymus_.
+
+Other genera belonging to this family are--_Benthophilus_ from the
+Caspian Sea; _Amblyopus_, _Orthostomus_, _Platyptera_, _Luciogobius_,
+_Oxymetopon_, and, perhaps, _Oxuderces_.
+
+
+            TENTH DIVISION--ACANTHOPTERYGII BLENNIIFORMES.
+
+_Body low, sub-cylindrical or compressed, elongate. Dorsal fin very
+long; the spinous portion of the dorsal, if distinct, is very long,
+as well developed, as the soft, or much more; sometimes the entire
+fin is composed of spines only; anal more or less long; caudal fin
+subtruncated or rounded, if present. Ventral fins thoracic or jugular,
+if present._
+
+
+                        FIRST FAMILY--CEPOLIDÆ.
+
+_Body very elongate, compressed, covered with very small cycloid
+scales; eyes rather large, lateral. Teeth of moderate size. No bony
+stay for the angle of the præoperculum. One very long dorsal fin,
+which, like the anal, is composed of soft rays. Ventrals thoracic,
+composed of one spine and five rays. Gill-opening wide. Caudal vertebræ
+exceedingly numerous._
+
+The “Band-fishes” (_Cepola_) are small marine fishes, belonging
+principally to the fauna of the northern temperate zone; in the Indian
+Ocean the genus extends southwards to Pinang. The European species (_C.
+rubescens_) is found in isolated examples on the British coast, but is
+less scarce in some years than in others. These fishes are of a nearly
+uniform red colour.
+
+
+                     SECOND FAMILY--TRICHONOTIDÆ.
+
+_Body elongate, sub-cylindrical, covered with cycloid scales of
+moderate size. Eyes directed upwards. Teeth in villiform bands. No
+bony stay for the angle of the præoperculum. One long dorsal fin, with
+simple articulated rays, and without a spinous portion; anal long.
+Ventrals jugular, with one spine and five rays. Gill-opening very wide.
+The number of caudal vertebræ much exceeding that of the abdominal._
+
+Small marine fishes, belonging to two genera only, _Tricho__notus_
+(_setigerus_) from Indian Seas, with some of the anterior dorsal rays
+prolonged into filaments; and _Hemerocoetes_ (_acanthorhynchus_) from
+New Zealand, and sometimes found far out at sea on the surface.
+
+                    THIRD FAMILY--HETEROLEPIDOTIDÆ.
+
+_Body oblong, compressed, scaly; eyes lateral; cleft of the mouth
+lateral; dentition feeble. The angle of the præoperculum connected by a
+bony stay with the infraorbital ring. Dorsal long, with the spinous and
+soft portions equally developed; anal elongate. Ventrals thoracic, with
+one spine and five rays._
+
+  [Illustration: Fig. 222.--Scale from the lateral line of
+  Hemerocœtes acanthorhynchus, with lacerated margin.]
+
+  [Illustration: Fig. 223.--_Chirus hexagrammus_, from Japan.]
+
+Small shore-fishes, characteristic of the fauna of the Northern
+Pacific, some of the species occurring on the American as well as
+Asiatic side. They have been referred to several genera, as
+
+   CHIRUS, which is distinguished by the presence of several
+   lateral lines;
+
+   OPHIODON, with one lateral line only, cycloid scales, and
+   slightly armed præoperculum;
+
+   AGRAMMUS, with one lateral line only, ctenoid scales, and
+   unarmed præoperculum; and
+
+   ZANIOLEPIS, with one lateral line and minute comb-like scales.
+
+
+                       FOURTH FAMILY--BLENNIIDÆ.
+
+_Body elongate, low, more or less cylindrical, naked or covered with
+scales, which generally are small. One, two, or three dorsal fins
+occupying nearly the whole length of the back, the spinous portion,
+if distinct, being as much developed as the soft, or more; sometimes
+the entire fin is composed of spines; anal fin long. Ventrals jugular,
+composed of a few rays, and sometimes rudimentary or entirely absent.
+Pseudobranchiæ generally present._
+
+Littoral forms of great generic variety, occurring abundantly in
+all temperate and tropical seas. Some of the species have become
+acclimatised in fresh water, and many inhabit brackish water. With
+very few exceptions they are very small, some of the smallest
+fishes belonging to the family of “Blennies.” One of the principal
+characteristics of the Blennies is the ventral fin, which is formed by
+less than five rays, and has a jugular position. The Blennies have this
+in common with many Gadoids, and it is sometimes difficult to decide to
+which of these two families a fish should be referred. In such doubtful
+cases the presence of the pseudobranchiæ (which are absent in Gadoids)
+may be of assistance.
+
+In many Blennies the ventral fins have ceased to have any function, and
+become rudimentary, or are even entirely absent. In others the ventral
+fins, although reduced to cylindrical stylets, possess a distinct
+function, and are used as organs of locomotion, by the aid of which the
+fish moves rapidly over the bottom.
+
+The fossil forms are scarcely known; _Pterygocephalus_ from Monte Bolca
+appears to have been a Blennioid.
+
+   ANARRHICHAS.--Body elongate, with rudimentary scales; snout
+   rather short; cleft of the mouth wide; strong conical teeth in
+   the jaws, those on the sides with several pointed tubercles; a
+   biserial band of large molar teeth on the palate. Dorsal fin
+   long, with flexible spines; caudal separate. Ventrals none.
+   Gill-openings wide.
+
+The “Sea-wolf,” or “Sea-cat” (_A. lupus_), is a gigantic Blenny,
+attaining to a length of more than six feet. With its enormously strong
+tubercular teeth it is able to crush the hardest shells of Crustaceans
+or Mollusks, on which it feeds voraciously. It is an inhabitant of the
+northern seas, like two other allied species, all of which are esteemed
+as food by the inhabitants of Iceland and Greenland. Two other species
+of Sea-wolves occur in the corresponding latitudes of the North Pacific.
+
+  [Illustration: Fig. 224.--Teeth of the Wolf-fish, _Anarrhichas
+  lupus_.]
+
+   BLENNIUS.--Body moderately elongate, naked; snout short. A
+   single dorsal, without detached portion; ventrals jugular,
+   formed by a spine and two rays. Cleft of the mouth narrow; a
+   single series of immovable teeth in the jaws; generally a curved
+   tooth behind this series in both jaws, or in the lower only. A
+   more or less developed tentacle above the orbit. Gill-opening
+   wide.
+
+About forty species of Blennius (in the restricted generic sense)
+are known from the northern temperate zone, the tropical Atlantic,
+Tasmania, and the Red Sea. But in the tropical Indian Ocean they are
+almost entirely absent, and replaced by other allied genera. Three
+species, found near the Sandwich Islands, are immigrants into the
+Pacific from the American Continent. They generally live on the coast,
+or attach themselves to floating objects, some species leading a
+pelagic life, hiding themselves in floating seaweed, in which they
+even propagate their species. All species readily accustom themselves
+to fresh water, and some (_B. vulgaris_) have become entirely
+acclimatised in inland lakes. British species are _B. gattorugine_
+(growing to a length of twelve inches), _B. ocellaris_, _B. galerita_,
+and _B. pholis_, the common “Shanny.”
+
+_Chasmodes_ is a genus allied to _Blennius_, from the Atlantic coasts
+of temperate North America.
+
+  [Illustration: Fig. 225.--Petroscirtes bankieri, from Hong-Kong.]
+
+   PETROSCIRTES.--Body moderately elongate, naked. Snout generally
+   short. A single dorsal fin; ventrals composed of two or three
+   rays. Cleft of the mouth narrow; a single series of immovable
+   teeth in the jaws; a strong curved canine tooth behind this
+   series, that of the lower jaw much stronger than that of the
+   upper. Head sometimes with tentacles. Gill-opening reduced to a
+   small fissure above the root of the pectoral.
+
+Thirty species, from the tropical Indo-Pacific, of small size.
+
+  [Illustration: Fig. 226.--Dentition of the same, enlarged.]
+
+   SALARIAS.--Body moderately elongate, naked; snout short, with
+   transverse cleft of the mouth; a series of numerous small
+   teeth in the jaws, implanted in the gum and movable; generally
+   a curved canine tooth on each side of the lower jaw, behind
+   the series of small teeth. Dorsal fin continuous, sometimes
+   divided into two portions by a more or less deep notch without a
+   detached anterior part. Ventral fins with two or three rays. A
+   tentacle above the orbit. Gill-openings wide.
+
+Sixty species are known from the tropical zone, extending northwards to
+Madeira, southwards to Chile and Tasmania. In certain individuals of
+some of the species a longitudinal cutaneous crest is developed; all
+young individuals lack it, and in some other species it is invariably
+absent. Singularly enough this crest is not always a sexual character,
+as one might have supposed from analogy, but in some species at least
+it is developed in both sexes. Mature males, however, have generally
+higher dorsal fins and a more intense and variegated coloration than
+females and immature males, as is also the case in _Blennius_.
+
+   CLINUS.--Body moderately elongate, covered with small scales;
+   snout rather short; a narrow band or series of small teeth in
+   the jaws and on the palate. Dorsal fin formed by numerous spines
+   and a few soft rays, without a detached anterior portion; anal
+   spines two. Ventrals with two or three rays. A tentacle above
+   the orbit. Gill-opening wide.
+
+Thirty species, from the coasts of tropical America and the southern
+temperate zone. Three other genera are closely allied to Clinus, viz.
+_Cristiceps_ and _Cremnobates_, in which the three anterior dorsal
+spines are detached from the rest of the fin; and _Tripterygium_, with
+three distinct dorsal fins, of which the two anterior are spinous. The
+species of these genera are as numerous as those of _Clinus_, occurring
+in many parts of tropical seas, in the Mediterranean, and being
+especially well represented in South Australia and New Zealand.
+
+   STICHÆUS.--Body elongate, covered with very small scales;
+   lateral line more or less distinct, sometimes several lateral
+   lines. Snout short; very small teeth in the jaws, and generally
+   on the palate. Dorsal fin long, formed by spines only. Ventrals
+   with two or three rays. Caudal fin distinct. Gill-openings
+   rather wide.
+
+Small fishes, peculiar to the coasts near the arctic circle, ranging
+southwards to the coasts of Japan and Scandinavia. Ten species.
+
+   BLENNIOPS.--Body moderately elongate, covered with very small
+   scales; lateral line none. Snout short; small teeth in the
+   jaws, none on the palate. Dorsal fin long, formed by spines
+   only. Ventrals with one spine and three rays. Caudal distinct.
+   Gill-openings of moderate width, the gill-membranes coalescent
+   across the isthmus.
+
+A fine but not common kind of Blenny (_B. ascanii_), from the British
+and Scandinavian coasts.
+
+   CENTRONOTUS.--Body elongate, covered with very small scales;
+   lateral line none. Snout short; very small teeth in the jaws.
+   Dorsal fin long, formed by spines only. Ventrals none or
+   rudimentary; caudal separate. Gill-openings of moderate width,
+   gill-membranes coalescent.
+
+Ten species are known from the northern coasts; southwards the genus
+extends to the coasts of France, New York, California, and Japan. _C.
+gunellus_, or the “Gunnel-fish” or “Butter-fish,” is common on the
+British coasts. _Apodichthys_ is allied to _Centronotus_, but the
+vertical fins are confluent; and a very large, excavated, pen-like
+spine lies hidden in a pouch in front of the anal fin. This spine is
+evidently connected in some way with the generative organs, as a furrow
+leads from the orifice of the oviduct to the groove of the spine. One
+species from the Pacific coast of North America. _Xiphidion_ is another
+closely allied genus from the same locality.
+
+   CRYPTACANTHODES.--Body very elongate, naked, with a single
+   lateral line. Head with the muciferous system well developed.
+   Eye rather small. Conical teeth in the jaws, on the vomer
+   and palatine bones. One dorsal formed by spines only; caudal
+   connected with dorsal and anal. Ventrals none. Gill-opening of
+   moderate width, with the gill-membranes joined to the isthmus.
+
+One species (_C. maculatus_) from the Atlantic coasts of North America.
+
+   PATÆCUS.--Body oblong, elevated anteriorly; snout short, with
+   subvertical anterior profile; minute teeth in the jaws and on
+   the vomer. Dorsal fin with the anterior spines strong and long,
+   continuous with the caudal; ventrals none. Gill-openings wide.
+
+  [Illustration: Fig. 227.--Patæcus fronto.]
+
+Three species of this singular form are known from South and West
+Australia.
+
+   ZOARCES.--Body elongate, with the scales rudimentary; conical
+   teeth in the jaws. Dorsal fin long, with a depression on the
+   tail, which is formed by a series of spines much shorter than
+   the rays. No other fin-spines. No separate caudal fin. Ventrals
+   short, formed by three or four rays. Gill-openings wide.
+
+Two species are known, one from the European, and the other from the
+North American side of the Atlantic. The former, _Z. viviparus_, is
+well known by the name of “Viviparous Blenny;” as is signified by this
+name it produces its young alive. These are so matured at the time of
+their birth that on their first exclusion they swim about with the
+utmost agility. No fewer than from two to three hundred young are
+sometimes produced by one female, and the abdomen of the mother is so
+distended before parturition that it is impossible to touch it without
+causing them to be extruded. Full grown individuals are about twelve
+inches long, but the American species (_Z. anguillaris_) attains to a
+length of two or three feet.
+
+Other genera of the family of Blennoids are:--_Blennophis_,
+_Nemophis_, _Plagiotremus_, _Neoclinus_, _Cebidichthys_, _Myxodes_,
+_Heterostichus_, _Dictyosoma_, _Lepidoblennius_, _Dactyloscopus_,
+_Gunellichthys_, _Urocentrus_, _Stichæopsis_, _Sticharium_,
+_Notograptus_, _Pholidichthys_, and _Pseudoblennius_.
+
+
+                     FIFTH FAMILY--ACANTHOCLINIDÆ.
+
+_Body elongate, low, compressed, covered with small scales. One
+dorsal fin, occupying nearly the whole of the back, and chiefly
+composed of spines. Anal fin long, with numerous spines. Ventrals
+jugular, composed of a few rays only._
+
+Of this family one fish only is known (_Acanthoclinus littoreus_),
+a small Blenny abundant on the coast of New Zealand.
+
+
+                     SIXTH FAMILY--MASTACEMBELIDÆ.
+
+_Body elongate, eel-like, covered with very small scales. Mandible
+long, but little moveable. Dorsal fin very long, the anterior portion
+composed of numerous short isolated spines; anal fin with spines
+anteriorly. Ventrals none. The humeral arch is not suspended from the
+skull. Gill-openings reduced to a slit at the lower part of the side of
+the head._
+
+Freshwater-fishes characteristic of and almost confined to the Indian
+region. The structure of the mouth and of the branchial apparatus, the
+separation of the humeral arch from the skull, the absence of ventral
+fins, the anatomy of the abdominal organs, affords ample proof that
+these fishes are Acanthopterygian eels. Their upper jaw terminates
+in a pointed moveable appendage, which is concave and transversely
+striated inferiorly in _Rhynchobdella_, and without transverse striæ in
+_Mastacembelus_: the only two genera of this family. Thirteen species
+are known, of which _Rh. aculeata_, _M. pancalus_ and _M. armatus_
+are extremely common, the latter attaining to a length of two feet.
+Outlying species are _M. aleppensis_ from Mesopotamia and Syria, and
+_M. cryptacanthus_, _M. marchei_, and _M. niger_, from West Africa.
+
+  [Illustration: Fig. 228.--Mastacembelus argus, from Siam.]
+
+
+           ELEVENTH DIVISION--ACANTHOPTERYGII MUGILIFORMES.
+
+_Two dorsal fins more or less remote from each other; the anterior
+either short, like the posterior, or composed of feeble spines. Ventral
+fins with one spine and five rays, abdominal._
+
+
+                       FIRST FAMILY--SPHYRÆNIDÆ.
+
+_Body elongate, sub-cylindrical, covered with small cycloid scales;
+lateral line continuous. Cleft of the mouth wide, armed with strong
+teeth. Eye lateral, of moderate size. Vertebræ twenty-four._
+
+This family consists of one genus only, _Sphyræna_, generally called
+“Barracudas,” large voracious fishes from the tropical and sub-tropical
+seas, which prefer the vicinity of the coast to the open sea. They
+attain to a length of eight feet, and a weight of forty pounds;
+individuals of this large size are dangerous to bathers. They are
+generally used as food, but sometimes (especially in the West Indies)
+their flesh assumes poisonous qualities, from having fed on smaller
+poisonous fishes. Seventeen species.
+
+The Barracudas existed in the tertiary epoch, their remains being
+frequently found at Monte Bolca. Some other fossil genera have been
+associated with them, but as they are known from jaws and teeth
+or vertebræ only, their position in the system cannot be exactly
+determined; thus _Sphyrænodus_ and _Hypsodon_ from the chalk of Lewes,
+and the London clay of Sheppey. The American _Portheus_ is allied to
+_Hypsodon_. Another remarkable genus from the chalk, _Saurocephalus_,
+has been also referred to this family.[44]
+
+
+                      SECOND FAMILY--ATHERINIDÆ.
+
+_Body more or less elongate, sub-cylindrical, covered with scales of
+moderate size; lateral line indistinct. Cleft of the mouth of moderate
+width, with the dentition feeble. Eye lateral, large or of moderate
+size. Gill-openings wide. Vertebræ very numerous._
+
+Small carnivorous fishes inhabiting the seas of the temperate and
+tropical zones; many enter fresh water, and some have been entirely
+acclimatised in it. This family seems to have been represented in the
+Monte Bolca formation by _Mesogaster_.
+
+   ATHERINA.--Teeth very small; scales cycloid. The first dorsal is
+   short and entirely separated from the second. Snout obtuse, with
+   the cleft of the mouth straight, oblique, extending to or beyond
+   the anterior margin of the eye.
+
+The Atherines are littoral fishes, living in large shoals, which habit
+has been retained by the species acclimatised in fresh water. They
+rarely exceed a length of six inches, but are nevertheless esteemed
+as food. From their general resemblance to the real Smelt they are
+often thus misnamed, but may always be readily recognised by their
+small first spinous dorsal fin. The young, for some time after they
+are hatched, cling together in dense masses, and in numbers almost
+incredible. The inhabitants of the Mediterranean coast of France call
+these newly hatched Atherines “Nonnat” (unborn). Some thirty species
+are known, of which _A. presbyter_ and _A. boyeri_ occur on the British
+coast.
+
+   ATHERINICHTHYS, distinguished from _Atherina_ in having the
+   snout more or less produced; and the cleft of the mouth
+   generally does not extend to the orbit.
+
+These Atherines are especially abundant on the coasts and in the fresh
+waters of Australia and South America. Of the twenty species known,
+several attain a length of eighteen inches and a weight of more than a
+pound. All are highly esteemed as food; but the most celebrated is the
+“Pesce Rey” of Chile (_A. laticlavia_).
+
+   TETRAGONURUS.--Body rather elongate, covered with strongly
+   keeled and striated scales. The first dorsal fin is composed
+   of numerous feeble spines, and continued on to the second.
+   Lower jaw elevated, with convex dental margin, and armed with
+   compressed, triangular, rather small teeth, in a single series.
+
+This very remarkable fish is more frequently met with in the
+Mediterranean than in the Atlantic, but generally scarce. Nothing is
+known of its habits; when young it is one of the fishes which accompany
+Medusæ, and, therefore, it must be regarded as a pelagic form.
+Probably, at a later period of its life, it descends to greater depths,
+coming to the surface at night only. It grows to a length of eighteen
+inches.
+
+
+                        THIRD FAMILY--MUGILIDÆ.
+
+_Body more or less oblong and compressed, covered with cycloid scales
+of moderate size; lateral line none. Cleft of the mouth narrow or of
+moderate width, without or with feeble teeth. Eye lateral, of moderate
+size. Gill-opening wide. The anterior dorsal fin composed of four stiff
+spines. Vertebræ twenty-four._
+
+The “Grey Mullets” inhabit in numerous species and in great numbers the
+coasts of the temperate and tropical zones. They frequent brackish
+waters, in which they find an abundance of food which consists chiefly
+of the organic substances mixed with mud or sand; in order to prevent
+larger bodies from passing into the stomach, or substances from passing
+through the gill-openings, these fishes have the organs of the pharynx
+modified into a filtering apparatus. They take in a quantity of sand or
+mud, and, after having worked it for some time between the pharyngeal
+bones, they eject the roughest and indigestible portion of it. The
+upper pharyngeals have a rather irregular form; they are slightly
+arched, the convexity being directed towards the pharyngeal cavity,
+tapering anteriorly and broad posteriorly. They are coated with a thick
+soft membrane, which reaches far beyond the margin of the bone, at
+least on its interior posterior portion; this membrane is studded all
+over with minute horny cilia. The pharyngeal bone rests upon a large
+fatty mass, giving it a considerable degree of elasticity. There is a
+very large venous sinus between the anterior portion of the pharyngeal
+and the basal portion of the branchial arches. Another mass of fat,
+of elliptical form, occupies the middle of the roof of the pharynx,
+between the two pharyngeal bones. Each branchial arch is provided
+on each side, in its whole length, with a series of closely-set
+gill-rakers, which are laterally bent downwards, each series closely
+fitting into the series of the adjoining arch; they constitute together
+a sieve, admirably adapted to permit a transit for the water, retaining
+at the same time every other substance in the cavity of the pharynx.
+
+The lower pharyngeal bones are elongate, crescent-shaped, and
+broader posteriorly than anteriorly. Their inner surface is concave,
+corresponding to the convexity of the upper pharyngeals, and provided
+with a single series of lamellæ, similar to those of the branchial
+arches, but reaching across the bone from one margin to the other.
+
+The intestinal tract shows no less peculiarities. The lower portion
+of the œsophagus is provided with numerous long thread-like papillæ,
+and continued into the oblong-ovoid membranaceous cœcal portion of the
+stomach, the mucosa of which forms several longitudinal folds. The
+second portion of the stomach reminds one of the stomach of birds;
+it communicates laterally with the other portion, is globular, and
+surrounded by an exceedingly strong muscle. This muscle is not divided
+into two as in birds, but of great thickness in the whole circumference
+of the stomach, all the muscular fasciculi being circularly arranged.
+The internal cavity of this stomach is rather small, and coated with a
+tough epithelium, longitudinal folds running from the entrance opening
+to the pyloric, which is situated opposite to the other. A low circular
+valve forms a pylorus. There are five rather short pyloric appendages.
+The intestines make a great number of circumvolutions, and are seven
+feet long in a specimen thirteen inches in length.
+
+  [Illustration: Fig. 229.--Mugil proboscideus.]
+
+Some seventy species of Grey Mullets are known, the majority of
+which attain to a weight of about four pounds, but there are many
+which grow to ten and twelve pounds. All are eaten, and some even
+esteemed, especially when taken out of fresh water. If attention
+were paid to their cultivation, great profits could be made by fry
+being transferred into suitable backwaters on the shore, in which
+they rapidly grow to a marketable size. Several species are more or
+less abundant on the British coasts, as _Mugil octo-radiatus_ (Fig.
+105, p. 254), _M. capito_, _M. auratus_ (Fig. 106, p. 254), and _M.
+septentrionalis_ (Fig. 107, p. 254), which, with the aid of the
+accompanying figures, and by counting the rays of the anal fin, may be
+readily distinguished--_M. octo-radiatus_ having eight, and _M. capito_
+and _M. auratus_ nine soft rays. A species inhabiting fresh waters of
+Central America (_M. proboscideus_) has the snout pointed and fleshy,
+thus approaching certain other freshwater and littoral Mullets, which,
+on account of a modification of the structure of the mouth, have been
+formed into a distinct genus, _Agonostoma_. _Myxus_ comprises Mullets
+with teeth more distinct than in the typical species.
+
+This genus existed in the tertiary epoch, remains of a species having
+been found in the gypsum of Aix, in Provence.
+
+
+          TWELFTH DIVISION--ACANTHOPTERYGII GASTROSTEIFORMES.
+
+_The spinous dorsal is composed of isolated spines if present;
+the ventrals are either thoracic or have an abdominal position in
+consequence of the prolongation of the pubic bones which are attached
+to the humeral arch. Mouth small, at the end of the snout which is
+generally more or less produced._
+
+
+                      FIRST FAMILY--GASTROSTEIDÆ.
+
+_Body elongate, compressed. Cleft of the mouth oblique; villiform
+teeth in the jaws. Opercular bones not armed; infraorbitals covering
+the cheek; parts of the skeleton forming incomplete external mails.
+Scales none, but generally large scutes along the side. Isolated spines
+in front of the soft dorsal fin. Ventral fins abdominal, joined to
+the pubic bone, composed of a spine and a small ray. Branchiostegals
+three._
+
+  [Illustration: Fig. 230.--Gastrosteus noveboracensis.]
+
+Of “Sticklebacks” (_Gastrosteus_) about ten species are satisfactorily
+known, one of which (_G. spinachia_) lives in salt and brackish water,
+whilst the others inhabit principally fresh waters, although they all
+are able to exist in the sea. They are confined to the Temperate and
+Arctic zones of the northern hemisphere. The British freshwater species
+are the Three-spined Stickleback (_G. aculeatus_), which sometimes,
+especially in Central Europe, lacks scutes, sometimes has a series of
+scutes along the side of the body; the Four-spined Stickleback (_G.
+spinulosus_) and the Nine-spined Stickleback (_G. pungitius_). The
+commonest North American species is _G. noveboracensis_. The habits
+of all the freshwater species are very similar. The common European
+species (_G. aculeatus_) is an active and greedy little fish, extremely
+destructive to the fry of other species, and consequently injurious
+in ponds where these are sought to be preserved. It is scarcely to
+be conceived what damage these little fishes do, and how greatly
+detrimental they are to the increase of all the fishes in general among
+which they live; for it is with the utmost industry, sagacity, and
+greediness that they seek out and destroy all the young fry that come
+their way. A small Stickleback, kept in an aquarium, devoured, in five
+hours’ time, seventy-four young dace, which were about a quarter of
+an inch long, and of the thickness of a horse hair. Two days after it
+swallowed sixty-two; and would, probably, have eaten as many every day
+could they have been procured. The Stickleback sometimes swarms in
+prodigious numbers. Pennant states that at Spalding, in Lincolnshire,
+there was once in seven years amazing shoals, which appear in the
+Welland, coming up the river in the form of a vast column. The quantity
+may, perhaps, be conceived from the fact that a man employed in
+collecting them, gained, for a considerable time, four shillings a-day
+by selling them at the rate of a halfpenny a bushel. Costa, who studied
+the manners of these small fishes, relates that, on the approach of
+spawning time, the male builds a nest of stalks of grass and other
+matters in a hollow of the bottom, a little above three inches wide and
+about six inches and a half deep, creeping over the materials on his
+belly, and cementing them with the mucus that exudes from his skin.
+The bottom of the nest is first laid, then the sides are raised, and
+lastly the top is covered over. A small hole is left on one side for
+an entrance. When the erection is complete, he seeks out a female, and
+conducting her, Costa says, with many caresses, to the nest, introduces
+her by the door into the chamber. In a few minutes she has laid two or
+three eggs, after which she bores a hole on the opposite side of the
+nest to that by which she entered, and makes her escape. The nest has
+now two doors, and the eggs are exposed to the cool stream of water,
+which, entering by one door flows out at the other. Next day the male
+goes again in quest of a female, and sometimes brings back the same,
+sometimes finds a new mate. This is repeated until the nest contains
+a considerable number of eggs, and each time the male rubs his side
+against the female and passes over the eggs. Next the male watches
+a whole month over his treasure, defending it stoutly against all
+invaders, and especially against his wives, who have a great desire
+to get at the eggs. When the young are hatched and able to do for
+themselves his cares cease.
+
+The Sea-Stickleback (_G. spinachia_) is likewise a nest builder,
+choosing for its operations especially the shallows of brackish water,
+which are covered with _Zostera_.
+
+
+                     SECOND FAMILY--FISTULARIIDÆ.
+
+_Fishes of greatly elongated form; the anterior bones of the skull
+are much produced, and form a long tube, terminating in a narrow mouth.
+Teeth small; scales none, or small. The spinous dorsal fin is either
+formed by feeble isolated spines or entirely absent; the soft dorsal
+and anal of moderate length, ventral fins thoracic or abdominal,
+composed of five or six rays, without spine; if abdominal, they are
+separate from the pubic bones, which remain attached to the humeral
+arch. Branchiostegals five._
+
+The “Flute-mouths” are also frequently called “Pipe-fishes,” a name
+which they have in common with the Syngnathidæ. They are gigantic
+marine Sticklebacks, living near the shore, from which they are
+frequently driven into the open sea; some of the species, therefore,
+have a wide geographical range. Probably all enter brackish water. They
+are distributed over the whole of the tropical and sub-tropical parts
+of the Atlantic and Indo-Pacific. The species are few in number, but
+some of them are very common.
+
+This family is well represented in Eocene formations; some of the
+remains belonging to the existing genera, _Fistularia_, _Aulostoma_,
+and _Auliscops_, the two former of which occur not rarely at Monte
+Bolca and in the schists of Glaris. Well-preserved remains of
+_Auliscops_ have been found in the Marl-slates of the highlands of
+Padang in Sumatra. Extinct genera from Monte Bolca are _Urosphen_, the
+cylindrical body of which is terminated by a large cuneiform fin; and
+_Rhamphosus_, which has an immense spinous ray, denticulated behind,
+inserted on the nape.
+
+   FISTULARIA.--Body scaleless; caudal fin forked, with the two
+   middle rays produced into a filament; no free dorsal spines.
+
+Three species are known, common on the shores of the Tropical Atlantic
+(_F. tabaccaria_) and Indian Oceans (_F. serrata_ and _F. depressa_);
+they attain to a length of from four to six feet.
+
+The anterior portion of the vertebral column shows the same peculiarity
+as in _Dactylopterus_; it is a long compressed tube, composed of four
+elongate vertebræ, which are perfectly anchylosed; each of them has
+a pair of small foramina for blood-vessels. The neural spines and
+parapophyses of this tubiform portion are confluent into thin laminæ,
+the lateral of which are wing-like, and expanded in their anterior half.
+
+   AULOSTOMA.--Body covered with small scales. Caudal fin rhombic,
+   without prolonged rays; a series of isolated feeble dorsal
+   spines. Teeth rudimentary.
+
+Two species from the Tropical Atlantic and Indian Oceans.
+
+   AULISCOPS.--Body naked. Ventrals thoracic. Numerous spines in
+   front of the dorsal fin.
+
+One species (_A. spinescens_) from the Pacific coast of North America.
+_Aulorhynchus_ from the same sea, and _Aulichthys_ from Japan, are
+allied genera.
+
+
+         THIRTEENTH DIVISION--ACANTHOPTERYGII CENTRISCIFORMES.
+
+_Two dorsal fins; the spinous short, the soft and the anal of moderate
+extent. Ventral fins truly abdominal, imperfectly developed._
+
+This division consists of one family, _Centriscidæ_, with two genera.
+The fishes belonging to it are very small, marine, and, in consequence
+of their limited power of swimming, often driven out into the open
+sea. They have the same structure of the mouth and snout as the
+Fistulariidæ, but combine with it peculiarities of the shape of body,
+of the structure of the vertical fins, and of the relations between
+endo- and exo-skeleton, which render them altogether a singular and
+interesting type. _Amphisile_ has been found in a fossil state at Monte
+Bolca.
+
+   CENTRISCUS.--Body oblong or elevated, compressed, covered with
+   small rough scales; lateral line none; some bony strips on the
+   side of the back, and on the margin of the thorax and abdomen;
+   the former, in one species, are confluent and form a shield.
+   Teeth none. Two dorsal fins, the first with one of the spines
+   very strong. Ventral fins small, abdominal, composed of five
+   soft rays. Four branchiostegals.
+
+  [Illustration: Fig. 231.--Centriscus humerosus.]
+
+Of the four species the most generally known is _C. scolopax_, the
+“Trumpet-fish” or “Bellows-fish,” which rarely occurs on the south
+coast of England, is more common farther south, and reappears in
+Tasmania. The allied _C. gracilis_ is one of the fishes common to the
+Mediterranean and Japanese Seas. The species figured, _C. humerosus_,
+occurs on the coast of South Australia, and is very scarce.
+
+   AMPHISILE.--Body elongate, strongly compressed, provided with a
+   dorsal cuirass, which is formed by portions of the skeleton; the
+   longitudinal axis of the tail is not in the same line with that
+   of the trunk. Scales none. Teeth none. Two dorsal fins situated
+   on the hindmost part of the back; ventral fins rudimentary,
+   abdominal. Three or four branchiostegals.
+
+The three species known of this genus are found in the tropical
+Indo-Pacific. Their body is so thin that it has the appearance of
+being artificially compressed between two sheets of paper; it is
+semi-transparent, especially in the region of the air-bladder. The
+structure of the vertebral column is extremely singular and unique
+among Acanthopterygians. The abdominal portion is more than four
+times as long as the caudal; nevertheless it is composed of only
+six vertebræ, whilst the latter consists of fourteen. The abdominal
+vertebræ are extremely slender, the third alone being nearly as long
+as the whole caudal portion; they have a slight ridge superiorly
+and inferiorly, and on each side; the whole portion lying in the
+uppermost concavity of the dorsal cuirass. The caudal vertebræ are
+extremely short, and the strength of their neural and hæmal spines
+is in proportion to their size. The dorsal cuirass is not a dermal
+production, but formed by modified parts of the endoskeleton; its
+composition, the number and condition of its single parts, and,
+finally, the first dorsal spine, which in _A. punctulata_ is so
+singularly attached to it, favour this opinion. The plates, which
+occupy the vertebral line, would correspond to the neural spines, and
+the lateral plates on which the ribs are suspended to the parapophyses.
+_Amphisile_ may be considered as a Chelonian form among fishes.
+
+
+         FOURTEENTH DIVISION--ACANTHOPTERYGII GOBIESOCIFORMES.
+
+_No spinous dorsal; the soft and the anal short or of moderate length,
+situated on the tail; ventral fins subjugular, with an adhesive
+apparatus between them. Body naked._
+
+These fishes are well characterised by their single dorsal fin, and
+by their adhesive ventral apparatus, which has only an external
+similarity to the organ observed in _Cyclopterus_ and _Liparis_; its
+structure is typically different from it. Whilst in those genera the
+ventral fins occupy the centre of the disk forming its base, these
+fins are here widely apart from each other, as in _Callionymus_,
+forming only a portion of the periphery of the disk, which is completed
+by a cartilaginous expansion of the coracoid bones. The following
+description of its structure is taken from _Sicyases sanguineus_, but
+it is essentially the same in all the genera.
+
+The whole disk is exceedingly large, subcircular, longer than broad,
+its length being one-third of the whole length of the fish. The central
+portion is formed merely by skin, which is separated from the pelvic
+or pubic bones by several layers of muscles. The peripheric portion is
+divided into an anterior and posterior part by a deep notch behind the
+ventrals. The anterior peripheric portion is formed by the four ventral
+rays, the membrane between them, and a broad fringe which extends
+anteriorly from one ventral to the other; this fringe is a fold of
+the skin, containing on each side the rudimentary ventral spine, but
+no cartilage. The posterior peripheric portion is suspended on each
+side from the coracoid, the upper bone of which is exceedingly broad,
+becoming a free movable plate behind the pectoral. A broad cartilage
+is firmly attached to it. The lower bone of the coracoid is of a
+triangular form, and supports a very broad fold of the skin, extending
+from one side to the other, and containing a cartilage which runs
+through the whole of that fold. Five processes of the cartilage are
+continued into the soft striated margin in which the disk terminates
+posteriorly. The surface of the disk is coated with thick epidermis,
+like the sole of the foot of higher animals. The epidermis is divided
+into many polygonal plates; there are no such plates between the roots
+of the ventral fins.
+
+Not less unique is the structure of the bones which have some
+relation to this external adhesive apparatus. As exemplified by
+_Chorismochismus dentex_ the coracoid is well developed, and, as
+usual, composed of two pieces, the upper of which is not suspended from
+the humerus, but fixed by a ligament to the hinder margin of the carpal
+bones. It is a broad lamella, dilated posteriorly into the cartilage,
+which is externally visible; the lower piece is narrower, and fixed to
+the extremity of the pubic bone of its side. The pubic bones are united
+by suture, and form together a heart-shaped disk, the point of which
+is produced backwards. The anterior portion of the disk is concave,
+with a bony longitudinal bridge and a feeble transverse ridge. The disk
+is fixed to the humeral bones by the convex portions of its anterior
+margin, whilst the convex portions of the lateral margins serve as
+base for the ventral fins. The latter are composed of one spine, which
+is transformed into a broad, thin, and curved plate, hidden below the
+skin, and apparently of four rays; but on closer examination we find
+that the hidden ray has a longitudinal groove anteriorly, in which
+another thinner ray lies concealed. This ray is quite free, and not
+joined to the pubic bone.
+
+The fishes belonging to the single family of this division,
+_Gobiesocidæ_, are strictly marine but littoral fishes. They are
+scattered over the temperate zones of both hemispheres, and more
+numerous than between the Tropics. All are of small or very small size.
+
+  [Illustration: Fig. 232.--Gobiesox cephalus.]
+
+The adhesive disk consists of an anterior and posterior division. In
+some of the genera the posterior division has no free anterior margin,
+the teeth being either all conical, as in _Chorisochismus_ (Cape of
+Good Hope) and _Cotylis_ (Red Sea and Indian Ocean); or incisor-like
+in both jaws, as in _Sicyases_ (coast of Chili and West Indies); or
+incisor-like at least in the lower jaw, as in _Gobiesox_ (West Indies
+and Pacific coasts of South America). In other genera the posterior
+portion of the adhesive disk has a free anterior margin. Only one
+of these genera has incisor-like teeth, viz. _Diplocrepis_ from New
+Zealand. In the remaining genera, _Crepidogaster_ (from Tasmania and
+South Australia), _Trachelochismus_ (from New Zealand and the Fiji
+Islands), _Lepadogaster_, and _Leptopterygius_, the teeth are very
+small and fine. The two last genera are European, and _Lepadogaster_ at
+least is common on the Southern British coasts. The three species known
+as British--_L. gouanii_, _L. candollii_, and _L. bimaculatus_--are
+prettily coloured, but subject to great variation.
+
+  [Illustration: Fig. 233.--Diplocrepis puniceus.]
+
+
+           FIFTEENTH DIVISION--ACANTHOPTERYGII CHANNIFORMES.
+
+_Body elongate, covered with scales of moderate size; no spine in any
+of the fins; dorsal and anal long. No superbranchial organ, only a bony
+prominence on the anterior surface of the hyomandibular._
+
+These fishes belong to the single family _Ophiocephalidæ_,
+Freshwater-fishes characteristic of the Indian region, which, however,
+have found their way into Africa, where they are represented by one or
+two species. Thirty-one species are known altogether, most of which
+are extremely abundant; some attain to a length of more than two feet.
+Like other tropical freshwater fishes, they are able to survive
+droughts, living in semi-fluid mud, or lying in a torpid state below
+the hard-baked crusts of the bottom of a tank from which every drop
+of water has disappeared. Respiration is probably entirely suspended
+during the state of torpidity, but whilst the mud is still soft enough
+to allow them to come to the surface, they rise at intervals to take in
+a quantity of air, by means of which their blood is oxygenised. This
+habit has been observed in some species to continue also to the period
+of the year in which the fish lives in normal water, and individuals
+which are kept in a basin and prevented from coming to the surface
+and renewing the air for respiratory purposes, are suffocated. The
+particular manner in which the accessory branchial cavity participates
+in respiratory functions is not known. It is a simple cavity, without
+an accessory branchial organ, the opening of which is partly closed by
+a fold of the mucous membrane.
+
+  [Illustration: Fig. 234.--Ophiocephalus striatus, India.]
+
+
+        SIXTEENTH DIVISION--ACANTHOPTERYGII LABYRINTHIBRANCHII.
+
+_Body compressed, oblong or elevated, with scales of moderate size. A
+superbranchial organ in a cavity accessory to that of the gills._
+
+
+                      FIRST FAMILY--LABYRINTHICI.
+
+_Dorsal and anal spines present, but in variable numbers; ventrals
+thoracic. Lateral line absent, or more or less distinctly interrupted.
+Gill-opening rather narrow, the gill-membranes of both sides
+coalescent below the isthmus, and scaly; gills four; pseudobranchiæ
+rudimentary or absent._
+
+  [Illustration: Fig. 235.--Superbranchial organ of Anabas.]
+
+Freshwater-fishes of the Cyprinoid division of the Equatorial zone.
+They possess the faculty of being able to live for some time out of
+the water, or in thick or hardened mud, in a still greater degree than
+the fishes of the preceding family. In the accessory branchial cavity
+there is lodged a laminated organ which evidently has the function
+of assisting in the oxygenisation of the blood. In _Anabas_ it is
+formed by several exceedingly thin bony laminæ, similar in form to the
+auricle, and concentrically situated one above the other, the innermost
+being the largest. The degree in which these laminæ are developed
+is dependent on age. In specimens from one inch and a half to two
+inches and a half long there are only two such laminæ, a third being
+indicated by a small protuberance at the central base of the second
+or outer laminæ. In specimens of from three to four inches in length
+the third lamina is developed, covering one-half of the second. The
+edges of all the laminæ are straight, not valanced. In specimens of
+from four to five inches a fourth lamina makes its appearance in the
+basal centre of the third lamina. The other laminæ continue to grow in
+their circumference, and their edges now become undulated and slightly
+frilled. Cuvier and Valenciennes have examined still larger specimens.
+The figure given by them and reproduced here was taken from a specimen
+six or seven inches long, and shows the superbranchial organ composed
+of six laminæ.
+
+The air-bladder of the majority of these fishes is very large,
+extending far into the tail, and, therefore, divided behind by the
+hæmal spines into two lateral portions.
+
+The Labyrinthici are generally of small size; they are capable of being
+domesticated, and some of them deserve particular attention on account
+of the dazzling beauty of their colours or the flavour of their flesh.
+
+   ANABAS.--Body compressed, oblong; præorbital and orbitals
+   serrated. Small teeth in the jaws and on the vomer; none on
+   the palatines. Dorsal and anal spines numerous. Lateral line
+   interrupted.
+
+The “Climbing Perch” (_A. scandens_) is generally distributed over
+the Indian Region, and well known from its faculty of moving for some
+distance over land, and even up inclined surfaces. In 1797 Daldorf, in
+a memoir communicated to the Linnean Society of London, mentions that
+in 1791 he had himself taken an Anabas in the act of ascending a palm
+tree which grew near a pond. The fish had reached the height of five
+feet above the water, and was going still higher. In the effort to do
+this it held on to the bark of the tree by the preopercular spines,
+bent its tail, and stuck in the spines of the anal; then released its
+head, and, raising it, took a new hold with the preoperculum higher up.
+The fish is named in the Malayan language the “Tree Climber.” It rarely
+attains a length of seven inches.
+
+_Spirobranchus_ from the Cape, and _Ctenopoma_ from Tropical Africa,
+represent _Anabas_ in that continent.
+
+   POLYACANTHUS.--Body compressed, oblong; operculum without spines
+   or serrature; cleft of the mouth small, more or less oblique,
+   not extending beyond the vertical from the orbit, and little
+   protractile. Small fixed teeth in the jaws, none on the palate.
+   Dorsal and anal spines numerous; the soft dorsal and anal,
+   the caudal, and the ventral, more or less elongate in mature
+   specimens. Caudal rounded. Lateral line interrupted or absent.
+
+This genus is represented chiefly in the East Indian Archipelago; seven
+species are known; some of them have been domesticated on account of
+the beauty of their colours, and several varieties have been produced.
+One of them is to be mentioned, as, under the name of “Paradise-fish,”
+it has been introduced into the aquaria of Europe, where it readily
+breeds. It was known already to Lacépède, and has been mentioned since
+his time in all ichthyological works as _Macropus viridi-auratus_.
+In adult males some of the rays, and especially the caudal lobes, are
+much prolonged.
+
+   OSPHROMENUS.--Body compressed, more or less elevated; operculum
+   without spine or serrature. Small fixed teeth in the jaws, none
+   on the palate. Dorsal spines in small or moderate number; anal
+   spines in moderate or great number; ventral fins with the outer
+   ray very long, filiform. Lateral line not interrupted or absent.
+
+  [Illustration: Fig. 236.--Osphromenus olfax.]
+
+To this genus belongs the celebrated “Gourami” (_Osphromenus olfax_),
+reputed to be one of the best flavoured Freshwater-fishes in the
+East-Indian Archipelago. Its original home is Java, Sumatra, Borneo,
+and several other islands; but thence it has been transported to, and
+acclimatised in, Penang, Malacca, Mauritius, and even Cayenne. Being
+an almost omnivorous fish and tenacious of life, it seems to recommend
+itself particularly for acclimatisation in other tropical countries,
+and specimens kept in captivity become as tame as carps. It attains the
+size of a large turbot. A second, but much smaller, species of this
+genus, _O. trichopterus_, is frequently kept in vessels on account of
+the exquisite beauty of its varying iridescent metallic tints; like
+other fishes of this family it is very pugnacious.
+
+_Trichogaster_, a very common Bengalese fish, differs from
+_Osphromenus_ in having the ventral fins reduced to a single long
+filament.
+
+   BETTA.--Body compressed, oblong; operculum without spine or
+   serrature. Small fixed teeth in the jaws, none on the palate.
+   Dorsal fin short, on the middle of the back, without any pungent
+   spine; anal fin long. Ventral fin with five soft rays, the outer
+   one being produced. Lateral line interrupted or absent.
+
+A species of this genus (_B. pugnax_) is, on account of its
+pugnacious habits, reared by the Siamese. Cantor gives the following
+account:--“When the fish is in a state of quiet, its dull colours
+present nothing remarkable; but if two be brought together, or if
+one sees its own image in a looking-glass, the little creature
+becomes suddenly excited, the raised fins and the whole body shine
+with metallic colours of dazzling beauty, while the projected gill
+membrane, waving like a black frill round the throat, adds something
+of grotesqueness to the general appearance. In this state it makes
+repeated darts at its real or reflected antagonist. But both, when
+taken out of each other’s sight, instantly become quiet. This
+description was drawn up in 1840, at Singapore, by a gentleman who had
+been presented with several by the King of Siam. They were kept in
+glasses of water, fed with larvæ of mosquitoes, and had thus lived for
+many months. The Siamese are as infatuated with the combats of these
+fish as the Malays are with their cock-fights; and stake on the issue
+considerable sums, and sometimes their own persons and families. The
+license to exhibit fish-fights is farmed, and brings a considerable
+annual revenue to the King of Siam. The species abounds in the rivulets
+at the foot of the hills of Penang. The inhabitants name it ‘Pla-kat,’
+or the ‘Fighting-fish;’ but the kind kept especially for fighting is an
+artificial variety cultivated for the purpose.”
+
+MICRACANTHUS.--This genus represents the three last-named genera in
+Africa, where it has been recently discovered in tributaries of the
+river Ogooué. It seems to differ from the Indian genera chiefly by its
+more elongate body, the structure of the fins being scarcely different
+(D. 3/7, A. 4/23, V. 1/4).
+
+
+                    SECOND FAMILY--LUCIOCEPHALIDÆ.
+
+_Body elongate, covered with scales of moderate size. Lateral line
+present. Teeth small. Gill-opening wide; pseudobranchiæ none. The
+superbranchial organ is formed by two branchial arches, which are
+dilated into a membrane. One short dorsal fin; dorsal and anal spines
+none; ventrals composed of one spine and five rays. Air-bladder
+none._
+
+A small Freshwater-fish (_Luciocephalus pulcher_), from the
+East-Indian Archipelago.
+
+
+         SEVENTEENTH DIVISION--ACANTHOPTERYGII LOPHOTIFORMES.
+
+_Body riband shaped, with the vent near its extremity; a short anal
+behind the vent; dorsal fin as long as the body._
+
+Only one species is known of this division or family, _Lophotes
+cepedianus_. It is most probably a deep-sea fish, but does not descend
+to so great a depth as the _Trachypteridæ_, its bony and soft parts
+being well coherent. It is a scarce fish, hitherto found in the
+Mediterranean, off Madeira, and in the Sea of Japan; its length is
+known to exceed five feet. The head is elevated into a very high crest,
+and the dorsal fin commences with an exceedingly strong and long spine
+on the head. Silvery, with rose-coloured fins.
+
+
+           EIGHTEENTH DIVISION--ACANTHOPTERYGII TÆNIIFORMES.
+
+_Body riband shaped; dorsal fin as long as the body; anal absent;
+caudal rudimentary, or not in the longitudinal axis of the fish._
+
+  [Illustration: Fig. 237.--Trachypterus tænia.]
+
+The “Ribbon-fishes” are true deep-sea fishes, met with in all parts
+of the oceans, generally found when floating dead on the surface, or
+thrown ashore by the waves. Their body is like a band, specimens of
+from fifteen to twenty feet long being from ten to twelve inches deep,
+and about an inch or two broad at their thickest part. The eye is
+large and lateral; the mouth small, armed with very feeble teeth; the
+head deep and short. A high dorsal fin runs along the whole length of
+the back, and is supported by extremely numerous rays; its foremost
+portion, on the head, is detached from the rest of the fin, and
+composed of very elongate flexible spines. The anal fin is absent. The
+caudal fin (if preserved, which is rarely the case, in adult specimens)
+has an extra-axial position, being directed upwards like a fan. The
+ventrals are thoracic, either composed of several rays or reduced to a
+single long filament. The coloration is generally silvery, with rosy
+fins.
+
+When these fishes reach the surface of the water the expansion of the
+gases within their body has so loosened all parts of their muscular and
+bony system, that they can be lifted out of the water with difficulty
+only, and nearly always portions of the body and fins are broken and
+lost. The bones contain very little bony matter, are very porous, thin
+and light. At what depths Ribbon-fishes live is not known; probably
+the depths vary for different species; but although none have been
+yet obtained by means of the deep-sea dredge, they must be abundant
+at the bottom of all oceans, as dead fishes or fragments of them
+are frequently obtained. Some writers have supposed from the great
+length and narrow shape of these fishes that they have been mistaken
+for “Sea-serpents;” but as these monsters of the sea are always
+represented by those who have had the good fortune of meeting with them
+as remarkably active, it is not likely that harmless Ribbon-fishes,
+which are either dying or dead, have been the objects described as
+“Sea-serpents.”
+
+  [Illustration: Fig. 238.--Young Trachypterus.]
+
+Young Ribbon-fishes (from two to four inches) are not rarely met with
+near the surface; they possess the most extraordinary development of
+fin rays observed in the whole class of fishes, some of them being
+several times longer than the body, and provided with lappet-like
+dilatations. There is no doubt that fishes with such delicate
+appendages are bred and live in depths where the water is absolutely
+quiet, as a sojourn in the disturbed water of the surface would
+deprive them at once of organs which must be of some utility for their
+preservation.
+
+Ribbon-fishes are divided into three genera:--
+
+TRACHYPTERUS.--In which the ventral rays are well developed, and
+composed of several more or less branched rays. Specimens of this genus
+have been taken in the Mediterranean, Atlantic, at Mauritius, and in
+the Eastern Pacific. The “Deal-fish” (_T. arcticus_) is often met with
+in the North Atlantic, and specimens are generally found after the
+equinoctial gales on the coasts of the Orkneys and North Britain.
+
+STYLOPHORUS.--Without ventrals, and with the tail terminating in an
+exceedingly long cord-like appendage. Known from one specimen only,
+found at the beginning of this century between Cuba and Martinique. It
+is eleven inches long, and preserved in the Museum of the Royal College
+of Surgeons in London.
+
+_Regalecus._--Each ventral fin is reduced to a long filament, dilated
+at the extremity; caudal fin rudimentary or absent. These are the
+largest of all Ribbon-fishes, specimens being on record the length of
+which exceeded twenty feet. They have been taken in the Mediterranean,
+North and South Atlantic, Indian Ocean, and on the coast of New
+Zealand. They are frequently called “Kings of the herrings,” from
+the erroneous notion that they accompany the shoals of herrings; or
+“Oar-fishes,” from their two ventral fins, which have a dilatation at
+their extremity not unlike the blade of an oar. One or more species
+(_R. banksii_) are sometimes found on the British coasts, but they
+are very scarce, not more than sixteen captures having been recorded
+between the years 1759 and 1878.
+
+
+        NINETEENTH DIVISION--ACANTHOPTERYGII NOTACANTHIFORMES.
+
+_Dorsal fin short, composed of short, isolated spines, without a soft
+portion. Anal fin very long, anteriorly with many spines; ventrals
+abdominal, with more than five soft and several unarticulated rays._
+
+_Notacanthus_ is the most aberrant type of Acanthopterygians. Of
+the characteristics of this order the development of spines in the
+vertical fins is the only one preserved in the fishes of this genus.
+Their body is elongate, covered with very small scales; the snout
+protrudes beyond the mouth. Eyes lateral, of moderate size; dentition
+feeble. Five species are known from the Arctic Ocean, Mediterranean,
+Atlantic, and Southern Pacific. They inhabit considerable depths,
+probably from 100 to 400 fathoms, and during the “Challenger”
+expedition specimens have been obtained from an alleged depth of 1875
+fathoms.
+
+
+                             SECOND ORDER:
+
+                    ACANTHOPTERYGII PHARYNGOGNATHI.
+
+_Part of the rays of the dorsal, anal, and ventral fins are
+non-articulated spines. The lower pharyngeals coalesced. Air-bladder
+without pneumatic duct._
+
+  [Illustration: Fig. 239.--Coalescent Pharyngeals of Scarus
+  cretensis. _a_, upper; _b_, lower pharyngeals.]
+
+
+FIRST FAMILY--POMACENTRIDÆ.
+
+_Body short, compressed, covered with ctenoid scales. Dentition
+feeble; palate smooth. The lateral line does not extend to the caudal
+fin, or is interrupted. One dorsal fin, with the spinous portion as
+well developed as the soft, or more. Two, sometimes three, anal spines;
+the soft anal similar to the soft dorsal. Ventral fins thoracic, with
+one spine and five soft rays. Gills three and a half; pseudobranchiæ
+and air-bladder present. Vertebræ, twelve abdominal and fourteen
+caudal._
+
+  [Illustration: Fig. 240.--Dascyllus aruanus. Natural size, from
+  the Indo-Pacific.]
+
+The fishes of this family are marine; they resemble the Chætodonts
+with regard to their mode of life, living chiefly in the neighbourhood
+of coral formations. Like them they are beautifully coloured, the
+same patterns being sometimes reproduced in members of both families,
+proving that the development and distribution of colours is due to
+the agencies of climate, of the surroundings and of the habits of
+animals. The geographical range of the _Pomacentridæ_ is co-extensive
+with that of the Chætodonts, the species being most numerous in
+the Indo-Pacific and Tropical Atlantic, a few extending northwards
+to the Mediterranean and Japan, southwards to the coasts of South
+Australia. They feed chiefly on small marine animals, and such as
+have compressed teeth appear to feed on the small Zoophytes covering
+the banks, round which these “Coral-fishes” abound. In a fossil state
+this family is known from a single genus only, _Odonteus_, from Monte
+Bolca, allied to _Heliastes_. The recent genera belonging to this
+family are:--_Amphiprion_, _Premnas_, _Dascyllus_, _Lepidozygus_,
+_Pomacentrus_, _Glyphidodon_, _Parma_, and _Heliastes_. About 120
+species are known.
+
+
+                        SECOND FAMILY--LABRIDÆ.
+
+_Body oblong or elongate, covered with cycloid scales. The lateral
+line extends to the caudal, or is interrupted. One dorsal fin, with the
+spinous portion as well developed as, or more than, the soft. The soft
+anal similar to the soft dorsal. Ventral fins thoracic, with one spine
+and five soft rays. Palate without teeth. Branchiostegals five or six;
+gills three and a half; pseudobranchiæ and air-bladder present. Pyloric
+appendages none; stomach without cæcal sac._
+
+  [Illustration: Fig. 241.--Lips of a Wrasse, _Labrus
+  festivus_.]
+
+The “Wrasses” are a large family of littoral fishes, very abundant in
+the temperate and tropical zones, but becoming scarcer towards the
+Arctic and Antarctic circles, where they disappear entirely. Many of
+them are readily recognised by their thick lips, which are sometimes
+internally folded, a peculiarity which has given to them the German
+term of “Lip-fishes.” They feed chiefly on mollusks and crustaceans,
+their dentition being admirably adapted for crushing hard substances.
+Many species have a strong curved tooth at the posterior extremity of
+the intermaxillary, for the purpose of pressing a shell against the
+lateral and front teeth by which it is crushed. Other Wrasses feed on
+corals, others on zoophytes; a few are herbivorous. In all Wrasses
+the upper pharyngeal bones seem to be jointed to the basi-occipital;
+but whilst in _Labrus_ the basi-occipital is raised on each side
+into a large flattish condyle, fitting into a concavity of the upper
+pharyngeals, in _Scarus_ the mode of articulation is reversed,
+the basi-occipital having a pair of long grooves, in which the oblong
+condyles of the upper pharyngeals slide forwards and backwards.
+Beautiful colours prevail in this family, permanent pigmentary colours
+as well as passing iridescent reflections of the scales. Some species
+remain very small, others grow to a weight of fifty pounds. The larger
+kinds especially are prized as food, the smaller less so.
+
+Remains of Labridæ, recognised by their united pharyngeals, which bear
+molar-like teeth, are not scarce in tertiary formations of France,
+Germany, Italy, and England. Such remains from Monte Bolca and the
+Swiss Molasse have been referred to the genus _Labrus_. Others,
+_Nummopalatus_ and _Phyllodus_, are allied, but cannot be assigned,
+to one of the recent genera; the latter genus is first represented in
+cretaceous formations of Germany. Another genus, _Taurinichthys_, from
+the Miocene of France, represents the _Odacina_ of the living fauna.
+_Egertonia_, from the Isle of Sheppey, differs so much from all recent
+Labroid genera that its pertinence to this family appears doubtful.
+
+   [See _J. Cocchi_, Monografia dei Pharyngodopilidæ, 1866; and _E.
+   Sauvage_, Sur le genre Nummopalatus, in Bull. Soc. Geol. France,
+   1875.]
+
+   LABRUS.--Body compressed, oblong, covered with scales of
+   moderate size, in more than forty transverse series; snout more
+   or less pointed; imbricate scales on the cheeks and opercles;
+   none or only a few on the interoperculum. Teeth in the jaws
+   conical, in a single series. Dorsal spines numerous, thirteen
+   or twenty-one, none of which are prolonged; anal spines three.
+   Lateral line not interrupted.
+
+Young “Wrasses” differ from mature specimens in having the præoperculum
+serrated. The headquarters of this genus are the Mediterranean, whence
+it ranges, gradually diminishing towards the north, along all the
+shores of Europe. Nine species are known; British are the “Ballan
+Wrasse” (_L. maculatus_), and the “Striped or Red Wrasse” or “Cook”
+(_L. mixtus_). The two sexes of the latter species are very differently
+coloured; the male being generally ornamented with blue streaks, or a
+blackish band along the body, whilst the female has two or three large
+black blotches across the back of the tail.
+
+   CRENILABRUS are Labrus with serrated præoperculum; the number of
+   their dorsal spines varies from thirteen to eighteen, and the
+   scales are arranged in less than forty transverse series.
+
+The range of this genus is co-extensive with _Labrus_. _C. melops_, the
+“Gold-sinny,” or “Cork-wing,” is common on the British coasts.
+
+   TAUTOGA.--Body compressed, oblong, covered with small scales;
+   scales on the cheek rudimentary, opercles naked. Teeth in the
+   jaws conical, in double series; no posterior canine tooth.
+   Dorsal spines seventeen, anal spines three. Lateral line not
+   interrupted.
+
+The “Tautog,” or “Black-fish,” is common on the Atlantic coasts of
+temperate North America, and much esteemed as food.
+
+   CTENOLABRUS.--Body oblong, covered with scales of moderate size;
+   imbricate scales on the cheeks and opercles. Teeth in the jaws
+   in a band, with an outer series of stronger conical teeth; no
+   posterior canine tooth. Dorsal spines from sixteen to eighteen;
+   anal spines three. Lateral line not interrupted.
+
+Four species, from the Mediterranean and the temperate parts of the
+North Atlantic, _Ct. rupestris_ being common on the British, and
+_Ct. burgall_ on the North American coasts.
+
+   ACANTHOLABRUS.--A Wrasse with five or six anal spines, and with
+   the teeth in a band.
+
+From the Mediterranean and British coasts (_A. palloni_).
+
+   CENTROLABRUS.--Wrasses with four or five anal spines, and with
+   the teeth in a single series.
+
+Two species are known from Madeira and the Canary Islands, and one from
+northern Europe and Greenland. The latter is scarce on the British
+coasts, but bears a distinct name on the south coast, where it is
+called “Rock-cook.”
+
+LACHNOLAEMUS from the West Indies, and MALACOPTERUS from Juan
+Fernandez, are Labroids, closely allied to the preceding North Atlantic
+genera.
+
+   COSSYPHUS.--Body compressed, oblong, with scales of moderate
+   size; snout more or less pointed; imbricate scales on the cheeks
+   and opercles; basal portion of the vertical fins scaly. Lateral
+   line not interrupted. Teeth in the jaws in a single series; four
+   canine teeth in each jaw anteriorly; a posterior canine tooth.
+   Formula of the fins: D. 12/9–11, A. 3/12.
+
+Twenty species are known from the tropical zone and coasts adjoining
+it; some, like _G. gouldii_ from Tasmania, attain a length of
+three or four feet.
+
+   CHILINUS.--Body compressed, oblong, covered with large scales;
+   lateral line interrupted; cheeks with two series of scales;
+   præoperculum entire; teeth in a single series, two canines in
+   each jaw; no posterior canine tooth; lower jaw not produced
+   backwards. Dorsal spines subequal in length; formula of the
+   fins: D. 9–10/10–9, A. 3/8.
+
+Common in the tropical Indo-Pacific, whence more than twenty species
+are known. Hybrids between the different species of this genus are not
+uncommon.
+
+   EPIBULUS.--Closely allied to the preceding genus, but with
+   a very protractile mouth, the ascending branches of the
+   intermaxillaries, the mandibles, and the tympanic being much
+   prolonged.
+
+This fish (_E. insidiator_) is said to seize marine animals by
+suddenly thrusting out its mouth and engulphing those that come within
+the reach of the elongated tube. It attains a length of twelve inches,
+is common in the tropical Indo-Pacific, and varies much in coloration.
+
+   ANAMPSES.--Distinguished by its singular dentition, the
+   two front teeth of each jaw being prominent, directed forwards,
+   compressed, with cutting edge. D. 9/12, A. 3/12.
+
+Beautifully coloured fishes from the tropical Indo-Pacific. Ten species.
+
+   PLATYGLOSSUS.--Scales in thirty or less transverse series;
+   lateral line not interrupted. A posterior canine tooth. Dorsal
+   spines nine.
+
+Small beautifully coloured Coral-fishes, abundant in the equatorial
+zone and the coasts adjoining it. Some eighty species are known
+(inclusive of the allied genera _Stethojulis_, _Leptojulis_, and
+_Pseudojulis_).
+
+   NOVACULA.--Body strongly compressed, oblong, covered with
+   scales of moderate size; head compressed, elevated, obtuse,
+   with the supero-anterior profile more or less parabolic; head
+   nearly entirely naked. Lateral line interrupted. No posterior
+   canine tooth. D. 9/12, A. 3/12; the two anterior dorsal spines
+   sometimes remote or separate from the others.
+
+Twenty-six species are known from the tropical zone, and the warmer
+parts of the temperate zones. They are readily recognised by their
+compressed, knife-shaped body, and peculiar physiognomy; they scarcely
+exceed a length of twelve inches.
+
+   JULIS.--Scales of moderate size; lateral line not interrupted.
+   Head entirely naked. Snout of moderate extent, not produced; no
+   posterior canine tooth. Dorsal spines ten.
+
+Co-extensive with _Platyglossus_ in their geographical distribution,
+and of like beautiful coloration and similar habits. Some of the most
+common fishes of the Indo-Pacific, as _J. lunaris_, _trilobata_, and
+_dorsalis_, belong to this genus.
+
+   CORIS.--Scales small, in fifty or more transverse series;
+   lateral line not interrupted. Head entirely naked. Dorsal spines
+   nine.
+
+Twenty-three species, distributed like _Platyglossus_; two reach the
+south coast of England, _Coris julis_ and _C. giofredi_, said to be
+male and female of the same species. Some belong to the most gorgeously
+coloured kinds of the whole class of fishes.
+
+Genera allied to the preceding Labroids are--_Choerops_, _Xiphochilus_,
+_Semicossyphus_, _Trochocopus_, _Decodon_, _Pteragogus_, _Clepticus_,
+_Labrichthys_, _Labroides_, _Duymæria_, _Cirrhilabrus_, _Doratonotus_,
+_Pseudochilinus_, _Hemigymnus_, _Gomphosus_, _Cheilio_, and _Cymolutes_.
+
+   PSEUDODAX.--Scales of moderate size; lateral line continuous;
+   cheeks and opercles scaly. Each jaw armed with two pairs of
+   broad incisors, and with a cutting lateral edge; teeth of the
+   lower pharyngeal confluent, pavement-like. Dorsal spines eleven.
+
+One species (_P. moluccensis_) from the East Indian Archipelago.
+
+   SCARUS.--Jaws forming a sharp beak, the teeth being soldered
+   together. The lower jaw projecting beyond the upper. A single
+   series of scales on the cheek; dorsal spines stiff, pungent; the
+   upper lip double in its whole circuit. The dentigerous plate of
+   the lower pharyngeal is broader than long.
+
+The fishes of this genus, and the three succeeding, are known by the
+name of “Parrot-wrasses.” Of _Scarus_ one species (_S. cretensis_)
+occurs in the Mediterranean, and nine others in the tropical Atlantic.
+The first was held in high repute by the ancients, and Aristotle has
+several passages respecting its rumination. It was most plentiful and
+of the best quality in the Carpathian Sea, between Crete and Asia
+Minor, but was not unknown even in early times on the Italian coasts,
+though Columella says that it seldom passed beyond Sicily in his day.
+But in the reign of Claudius, according to Pliny, Optatus Elipentius
+brought it from the Troad, and introduced it into the sea between
+Ostium and Campagna. For five years all that were caught in the nets
+were thrown into the sea again, and from that time it was an abundant
+fish in that locality. In the time of Pliny it was considered to be
+the first of fishes _(Nunc Scaro datur principatus_); and the expense
+incurred by Elipentius was justified, in the opinion of the Roman
+gourmands, by the extreme delicacy of the fish. It was a fish, said
+the poets, whose very excrements the gods themselves were unwilling
+to reject. Its flesh was tender, agreeable, sweet, easy of digestion,
+and quickly assimilated; yet if it happened to have eaten an Aplysia,
+it produced violent diarrhœa. In short, there is no fish of which so
+much has been said by ancient writers. In the present day the Scarus of
+the Archipelago is considered to be a fish of exquisite flavour; and
+the Greeks still name it _Scaro_, and eat it with a sauce made of its
+liver and intestines. It feeds on fucus; and Valenciennes thinks that
+the necessity for masticating its vegetable diet thoroughly, and the
+working of it with that intent backwards and forwards in the mouth,
+may have given rise to the notion of its being a ruminant; and it is
+certain that its aliment is very finely divided when it reaches the
+stomach.
+
+  [Illustration: Fig. 242.--Scarichthys auritus.]
+
+   SCARICHTHYS.--Differing from _Scarus_ only in having flexible
+   dorsal spines.
+
+Two species from the Indo-Pacific.
+
+   CALLYODON.--Differing from _Scarichthys_ in having the upper lip
+   double posteriorly only.
+
+Nine species from the tropical zone.
+
+   PSEUDOSCARUS.--Jaws forming a strong beak, the teeth being
+   soldered together. The upper jaw projecting beyond the lower.
+   Two or more series of scales on the cheek. The dentigerous plate
+   of the lower pharyngeal longer than broad.
+
+This tropical genus contains by far the greatest number of Scaroid
+Wrasses, some seventy species being known, and a still greater number
+of names being introduced into the various Ichthyological works. They
+are beautifully coloured, but the colours change with age, and vary
+in an extraordinary degree in the same species. They rapidly fade
+after death, so that it is almost impossible to recognise in preserved
+specimens the species described from living individuals. Many attain
+to a rather large size, upwards of three feet in length. The majority
+are eaten, but some acquire poisonous properties from their food, which
+consists either of corals or of fucus.
+
+   ODAX.--The edge of each jaw is sharp, without distinct teeth.
+   The dentigerous plate of the lower pharyngeal triangular, much
+   broader than long. Cheeks and opercles scaly; scales of the body
+   small or rather small; lateral line continuous. Snout conical.
+   Dorsal spines rather numerous, flexible.
+
+  [Illustration: Fig. 243.--Odax radiatus.]
+
+Six species from the coasts of Australia and New Zealand. Small. The
+species figured (_O. radiatus_) is from Western Australia.
+
+   CORIDODAX.--Jaws as in _Odax_, head naked. Scales of the body
+   small; lateral line continuous. Snout of moderate extent. Dorsal
+   spines numerous, flexible.
+
+The “Butter-fish,” or “Kelp-fish” of the colonists of New Zealand
+(_C. pullus_), is prized as food, and attains to a weight of four
+or five pounds. It feeds on zoophytes, scraping them from the surface
+of the kelp, with its curiously formed teeth. Its bones are green, like
+those of _Belone_.
+
+OLISTHEROPS, from King George’s Sound, has scales of moderate size, but
+agrees otherwise with _Coridodax_.
+
+   SIPHONOGNATHUS.--Head and body very elongate, snout long, as in
+   _Fistularia_; upper jaw terminating in a long, pointed, skinny
+   appendage; opercles and cheeks scaly; scales of moderate size;
+   lateral line continuous. Dorsal spines numerous, flexible. Jaws
+   as in _Odax_; the dentigerous plate of the lower pharyngeal very
+   narrow.
+
+_S. argyrophanes_, from King George’s Sound, is the most aberrant
+type of Wrasses, whose principal characters are retained, but united
+with a form of the body which resembles that of a Pipe-fish.
+
+
+                      THIRD FAMILY--EMBIOTOCIDÆ.
+
+_Body compressed, elevated or oblong, covered with cycloid scales;
+lateral line continuous. One dorsal fin, with a spinous portion, and
+with a scaly sheath along the base, which is separated by a groove from
+the other scales; anal with three spines and numerous rays; ventral
+fins thoracic, with one spine and five rays. Small teeth in the jaws,
+none on the palate. Pseudobranchiæ present. Stomach siphonal, pyloric
+appendages none. Viviparous._
+
+Marine Fishes characteristic of the fauna of the temperate North
+Pacific, the majority living on the American side, and only a few
+on the Asiatic. All are viviparous (see Fig. 70, p. 159). Agassiz
+describes the development of the embryoes as a normal ovarian
+gestation, the sac containing the young not being the oviduct but
+the ovarian sheath, which fulfils the functions of the ovary. This
+organ presents two modes of arrangement: in one there is a series of
+triangular membranous flaps communicating with each other, between
+which the young are arranged, mostly longitudinally, the head of one
+to the tail of another, but sometimes with the bodies curved, to the
+number of eighteen or twenty; in the other, the cavity is divided by
+three membranes converging to a point, into four compartments, not
+communicating with each other except towards the genital opening, the
+young being arranged in the same longitudinal manner. The proportionate
+size of the young is very remarkable. In a female specimen 10½ inches
+long, and 4½ inches high, the young were nearly 3 inches long and 1
+inch high. Seventeen species are known, the majority of which belong to
+_Ditrema_, and one to _Hysterocarpus_. They do not attain to
+a large size, varying from three-quarters to three pounds in weight.
+
+
+                       FOURTH FAMILY--CHROMIDES.
+
+_Body elevated, oblong or elongate, scaly, the scales being generally
+ctenoid. Lateral line interrupted or nearly so. One dorsal fin, with a
+spinous portion; three or more anal spines; the soft anal similar to
+the soft dorsal. Ventral fins thoracic, with one spine and five rays.
+Teeth in the jaws small, palate smooth. Pseudobranchiæ none. Stomach
+coecal; pyloric appendages none._
+
+Freshwater-fishes of rather small size from the tropical parts of
+Africa and America; one genus from Western India. The species with
+lobate teeth, and with many circumvolutions of the intestines, are
+herbivorous, the other carnivorous.
+
+   ETROPLUS.--Body compressed, elevated, covered with ctenoid
+   scales of moderate size. Lateral line indistinct. Dorsal and
+   anal spines numerous. Teeth compressed, lobate, in one or
+   two series. Anterior prominences of the branchial arches not
+   numerous, short, conical, hard. Dorsal fin not scaly.
+
+Two species from Ceylon and Southern India.
+
+   CHROMIS.--Body compressed, oblong, covered with cycloid
+   scales of moderate size. Dorsal spines numerous, anal spines
+   three. Teeth compressed, more or less lobate, in one series.
+   Anterior prominences of the branchial arches short, thin,
+   lamelliform, non-serrated. Dorsal fin not scaly.
+
+Some twenty species are known from the fresh waters of Africa and
+Palestine; the most celebrated is the “Bulti,” or “Bolty,” of the Nile,
+one of the few well-flavoured fishes of that river; it grows to the
+length of twenty inches. Two or three species of this genus occur in
+the Jordan and Lake of Galilee.
+
+  [Illustration: Fig. 244.--_Chromis andreæ_, from the Lake of
+  Galilee.]
+
+   HEMICHROMIS, differing from _Chromis_ in having conical teeth in
+   one or two series.
+
+Ten species, the range of which is co-extensive with that of _Chromis_.
+One species, _H. sacra_, is abundant in the Lake of Galilee.
+
+   PARETROPLUS, differing from _Hemichromis_ in having nine anal
+   spines.
+
+One species from Madagascar.
+
+   ACARA.--Body compressed, oblong, covered with ctenoid scales
+   of moderate size. Dorsal spines numerous, anal spines three or
+   four; base of the soft dorsal nearly uncovered by scales. Teeth
+   in a band, small, conical. Anterior prominences of the first
+   branchial arch very short tubercles.
+
+Some twenty species are known from the fresh waters of Tropical
+America, _A. bimaculata_ being one of the most common fishes of
+that region. All are very small.
+
+   HEROS.--Differing from _Acara_ in having more than four anal
+   spines.
+
+Some fifty species are known from the fresh waters of Tropical America,
+especially Central America, where almost every large lake or river is
+tenanted by one or more peculiar species. They are of rather small
+size, rarely exceeding a length of twelve inches.
+
+  [Illustration: Fig. 245.--_Heros salvini_, from Central
+  America.]
+
+Genera allied to _Heros_, and likewise from Tropical America, are
+_Neetroplus_, _Mesonauta_, _Petenia_, _Uaru_, and _Hygrogonus_.
+
+   CICHLA.--Form of the body perch-like. Scales small; the spinous
+   and soft portions of the dorsal fin of nearly equal extent,
+   and separated by a notch; anal spines three. Each jaw with a
+   broad band of villiform teeth. The outer branchial arch with
+   lanceolate crenulated prominences along its concave side. Dorsal
+   and anal fins scaly.
+
+Four species from Brazil, Guyana, and Peru.
+
+   CRENICICHLA.--Body low, sub-cylindrical; scales small or rather
+   small. The spinous portion of the dorsal is much more developed
+   than the soft, both being continuous, and not separated by a
+   notch; anal spines three. Præopercular margin serrated. Each
+   jaw with a band of conical teeth. The outer branchial arch with
+   short tubercles. Dorsal and anal fins naked.
+
+Ten species from Brazil and Guyana.
+
+The following genera complete the list of South American Chromides:
+_Chætobranchus_, _Mesops_, _Satanoperca_, _Geophagus_, _Symphysodon_,
+and _Pterophyllum_.
+
+
+                       THIRD ORDER--ANACANTHINI.
+
+_Vertical and ventral fins without spinous rays. The ventral fins,
+if present, are jugular or thoracic. Air-bladder, if present, without
+pneumatic duct._
+
+These characters are common to all the members of this order, with
+the exception of a freshwater-fish from Tasmania and South Australia
+(_Gadopsis_), which has the anterior portion of the dorsal and anal
+fins formed of spines.
+
+
+                 FIRST DIVISION--ANACANTHINI GADOIDEI.
+
+_Head and body symmetrically formed._
+
+
+                        FIRST FAMILY--LYCODIDÆ.
+
+_Vertical fins confluent. Ventral fin, if present, small, attached to
+the humeral arch, jugular. Gill-opening narrow, the gill-membrane being
+attached to the isthmus._
+
+Marine littoral fishes of small size, resembling Blennies, chiefly
+represented in high latitudes, but a few living within the tropical
+zone.
+
+   LYCODES.--Body elongate, covered with minute scales imbedded in
+   the skin, or naked; lateral line more or less indistinct. Eye
+   of moderate size. Ventral small, short, rudimentary, jugular,
+   composed of several rays. Upper jaw overlapping the lower.
+   Conical teeth in the jaws, on the vomer, and on the palatine
+   bones. Barbel none. Five or six branchiostegals; gill-opening
+   narrow, the gill-membranes being attached to the isthmus.
+   Pseudobranchiæ present. Air-bladder none. Pyloric appendages
+   two, or rudimentary, or entirely absent. No prominent anal
+   papilla.
+
+  [Illustration: Fig. 246.--Lycodes mucosus, from Northumberland
+  Sound.]
+
+Nine species are known from the Arctic Ocean, four from the southern
+extremity of the American continent.
+
+   GYMNELIS.--Body elongate, naked. Eye of moderate size or rather
+   small. Ventrals none. Vent situated at some distance backwards
+   from the head. Small conical teeth in the jaws, on the vomer
+   and palatine bones. Jaws equal anteriorly. Barbel none. Six
+   branchiostegals; gill-opening narrow, the gill membranes being
+   attached to the isthmus. Pseudobranchiæ present; air-bladder
+   none. Pyloric appendages two; no prominent anal papilla.
+
+  [Illustration: Fig. 247.--Gymnelis viridis.]
+
+One species (_G. viridis_) from Greenland, the other (_G. pictus_) from
+the Straits of Magelhæn.
+
+The other genera belonging to this family are _Uronectes_ from Baffin’s
+Bay, _Microdesmus_ from Panama, _Blennodesmus_ from the coast of
+North-Eastern Australia, and _Maynea_ from the Straits of Magelhæn.
+
+
+                        SECOND FAMILY--GADIDÆ.
+
+_Body more or less elongate, covered with small smooth scales. One,
+two, or three dorsal fins, occupying nearly the whole of the back; rays
+of the posterior dorsal well developed; one or two anal fins. Caudal
+free from dorsal and anal, or, if they are united, the dorsal with a
+separate anterior portion. Ventrals jugular, composed of several rays,
+or, if they are reduced to a filament, the dorsal is divided into two.
+Gill-opening wide; the gill-membranes generally not attached to the
+isthmus. Pseudobranchiæ none, or glandular, rudimentary. An air-bladder
+and pyloric appendages generally present._
+
+The family of “Cod-fishes” consists partly of littoral and surface
+species (and they form the majority), partly of deep-sea forms. The
+former are almost entirely confined to the temperate zones, extending
+beyond the Arctic Circle; the latter have, as deep-sea fishes
+generally, a much wider range, and hitherto have been found chiefly at
+considerable depths of rather low latitudes. Only two or three species
+inhabit fresh waters. They form one of the most important articles of
+food and subsistence to the fishermen in Europe and North America, and
+to whole tribes bordering upon the Arctic Ocean.
+
+Fossil remains are scarce. _Nemopteryx_ and _Palæogadus_ have been
+described from the schists of Glaris, a formation believed to have been
+the bottom of a very deep sea. In the clay of Sheppey species occur
+allied to _Gadus_, _Merluccius_, and _Phycis_; others, not readily
+determinable, have been found at Licata in Sicily (Miocene).
+
+   GADUS.--Body moderately elongate, covered with small scales.
+   A separate caudal, three dorsal, and two anal fins; ventrals
+   narrow, composed of six or more rays. Teeth in the upper jaw in
+   a narrow band; vomerine teeth; none on the palatines.
+
+Arctic and temperate zones of the Northern Hemisphere. Eighteen species
+are known, of which the following are the most important:--
+
+_Gadus morrhua_, the common “Cod-fish”--in German called “Kabeljau”
+when fresh and old, “Dorsch” when young and fresh, “Stock-fish” when
+dried, “Labberdan” when salted--measures from two to four feet, and
+attains to a weight of one hundred pounds. On the British coasts and
+in the German Ocean it is generally of a greenish or brownish-olive
+colour, with numerous yellowish or brown spots. Farther northwards
+darker-coloured specimens, frequently without any spots, predominate;
+and on the Greenland, Iceland, and North Scandinavian coasts the Cod
+have often a large irregular black blotch on the side. The Cod-fish
+occurs between 50° and 75° lat. N., in great profusion, to a depth of
+120 fathoms, but is not found nearer the Equator than 40° lat. Close
+to the coast it is met with singly all the year round, but towards
+the spawning-time it approaches the shore in numbers, which happens
+in January in England and not before May on the American coasts. The
+English resorted to the cod-fisheries of Iceland before the year
+1415, but since the sixteenth century most vessels go to the banks of
+Newfoundland, and almost all the preserved Cod consumed during Lent in
+the various continental countries is imported from across the Atlantic.
+At one time the Newfoundland cod-fishery rivalled in importance the
+whale-fishery and the fur trade of North America. Cod-liver oil is
+prepared from the liver on the Norwegian coast, but also other species
+of this genus contribute to this most important drug.
+
+_Gadus tomcodus_ abundantly occurs on the American coasts; it remains
+within smaller dimensions than the common Cod-fish. _Gadus æglefinus_,
+the “Haddock” (“Schell-fisch” of the Germans, “Hadot” of the French),
+is distinguished by a black lateral line and a blackish spot above
+the pectoral fin. It attains to a length of three feet in the higher
+latitudes, but remains smaller on more southern coasts; like the Cod
+it extends across the Atlantic. The largest specimens are taken on
+the British coast in winter, because at that time they leave the deep
+water to spawn on the coast. _Gadus merlangus_, the “Whiting,” with a
+black spot in the axil of the pectoral fin. _Gadus luscus_, the “Bib,”
+“Pout,” or “Whiting-pout,” with cross-bands during life, and with a
+black axillary spot, rarely exceeding a weight of five pounds. _Gadus
+fabricii_, a small species, but occurring in incredible numbers on
+the shores near the Arctic circle, and ranging to 80° lat. N. _Gadus
+pollachius_, the “Pollack,” without a barbel at the chin, and with the
+lower jaw projecting beyond the upper. _Gadus virens_, the “Coal-fish,”
+valuable on account of its size and abundance, and therefore preserved
+for export like the Cod.
+
+The fishes of the genus _Gadus_ are bathymetrically succeeded by
+several genera, as _Gadiculus_, _Mora_, and _Strinsia_; however these
+do not descend to sufficiently great depths to be included into the
+deep-sea Fauna; the two following are true deep-sea fishes.
+
+   HALARGYREUS.--Body elongate, covered with small scales. Two
+   dorsal and two anal fins; ventrals composed of several rays.
+   Jaws with a band of minute villiform teeth; vomer and palatines
+   toothless. No barbel.
+
+The single species known, _H. johnsonii_, proves to be a deep-sea fish
+by its organisation as well as geographical distribution. Originally
+known from a single specimen, which was obtained at Madeira, it has
+since been found off the coast of New Zealand. There is no doubt that
+it will be discovered also in intermediate seas.
+
+   MELANONUS.--Head and body rather compressed, covered with
+   cycloid scales of moderate size, and terminating in a long
+   tapering tail, without caudal. Eye of moderate size. Villiform
+   teeth in the jaws, on the vomer and palatine bones. Barbel
+   none. A short anterior dorsal, the second extending to the end
+   of the tail, and the anal being of similar length. Ventrals
+   composed of several rays. Bones soft and flexible.
+
+This is one of the discoveries made during the expedition of the
+“Challenger.” The single specimen obtained is of a deep-black colour,
+and was dredged up at a depth of 1975 fathoms in the Antarctic Ocean.
+
+   MERLUCCIUS.--Body elongate, covered with very small scales. A
+   separate caudal; two dorsal fins and one anal; ventrals well
+   developed, composed of seven rays. Teeth in the jaws and on the
+   vomer rather strong, in double or triple series. No barbel.
+
+Two species are known of this genus, widely separated in their
+distribution. The European species, _M. vulgaris_, the “Hake,” is found
+on both sides of the Atlantic, and grows to a length of four feet. It
+is caught in great numbers, and preserved as “Stock-fish.” The second
+species _M. gayi_, is common in the Straits of Magelhæn and on the
+coast of Chili, less so in New Zealand.
+
+The vertebral column of this genus shows a singular modification of
+the apophyses. The neural spines of all the abdominal vertebræ are
+extremely strong, dilated, wedged into one another. The parapophyses
+of the third to sixth vertebræ are slender, styliform, whilst those of
+all the following abdominal vertebræ are very long and broad, convex on
+the upper and concave on the lower surface; the two or three anterior
+pairs are, as it were, inflated. The whole forms a strong roof for the
+air-bladder, reminding us of a similar structure in _Kurtus_.
+
+   PSEUDOPHYCIS.--Body of moderate length, covered with rather
+   small scales. A separate caudal, two dorsals, and one anal;
+   ventral fins very narrow and styliform, but composed of several
+   rays. Jaws with a band of small teeth; vomer and palatines
+   toothless. Chin with a barbel.
+
+Two species, of which _Ps. bachus_ is common on the coast of New
+Zealand.
+
+Allied genera are _Lotella_, _Physiculus_, _Uraleptus_, and _Læmonema_,
+from moderate depths, obtained chiefly off Madeira and the Southern
+Temperate Zone.
+
+  [Illustration: Fig. 248.--Pseudophycis bachus.]
+
+   PHYCIS.--Body of moderate length, covered with small scales.
+   Fins more or less enveloped in loose skin. A separate caudal;
+   two dorsal fins and one anal; the anterior dorsal composed of
+   from eight to ten rays; ventrals reduced to a single long ray,
+   bifid at its end. Small teeth in the jaws and on the vomer;
+   palatine bones toothless. Chin with a barbel.
+
+Six species from the temperate parts of the North Atlantic and the
+Mediterranean, one, _Ph. blennioides_, is occasionally found on
+the British coast.
+
+   HALOPORPHYRUS.--Body elongate, covered with small scales. A
+   separate caudal, two dorsal fins, and one anal; the first dorsal
+   with four rays; ventrals narrow, composed of six rays. Jaws and
+   vomer with villiform teeth; palatine bones toothless. Chin with
+   a barbel.
+
+A small genus of deep-sea fishes, of which three species are known.
+They offer a striking instance of the extraordinary distribution of
+deep-sea fishes; _H. lepidion_ occurs in from 100 to 600 fathoms
+in the Mediterranean and the neighbouring parts of the Atlantic, off
+the coast of Japan, and various parts of the South Atlantic; _H.
+australis_ in from 55 to 70 fathoms in the Straits of Magelhæn; and
+finally _H. rostratus_ in from 600 to 1375 fathoms, midway between
+the Cape of Good Hope and Kerguelen’s Land, and in the South Atlantic.
+
+   LOTA.--Body elongate, covered with very small scales. A separate
+   caudal, two dorsal fins, and one anal; ventrals narrow, composed
+   of six rays. Villiform teeth in the jaws and on the vomer; none
+   on the palatines. The first dorsal with from ten to thirteen
+   well-developed rays. Chin with a barbel.
+
+The “Burbot,” or “Eel-pout” (_L. vulgaris_, Fig. 8, p. 43), is
+a Freshwater-fish which never enters salt water. It is locally
+distributed in Central and Northern Europe and North America; it is one
+of the best Freshwater-fishes, and exceeds a length of three feet.
+
+   MOLVA.--Differs from Lota in having several large teeth in the
+   lower jaw and on the vomer.
+
+The “Ling” (_M. vulgaris_) is a very valuable species, common on the
+northern coasts of Europe, Iceland, and Greenland; and generally found
+from three to four feet long. The larger number of the specimens caught
+are cured and dried.
+
+   MOTELLA.--Body elongate, covered with minute scales. A separate
+   caudal. Two dorsal fins, the anterior of which is reduced to a
+   narrow rayed fringe, more or less concealed in a longitudinal
+   groove; the first ray is prolonged. One anal fin. Ventrals
+   composed of from five to seven rays. A band of teeth in the jaws
+   and on the vomer.
+
+Eight species of “Rocklings” are known from the coasts of Europe,
+Iceland, Greenland, Japan, the Cape of Good Hope, and New Zealand.
+They are of small size, and chiefly distinguished by the number of
+their barbels. British are the Five-bearded Rockling (_M. mustela_),
+the Three-bearded Rocklings (_M. tricirrhata_, _macrophthalma_,
+and _maculata_), and the Four-bearded Rockling (_M. cimbria_). _M.
+macrophthalma_ comes from a depth of from 80 to 180 fathoms. The young
+are known as “Mackerel Midge” (_Couchia_), and sometimes met with in
+large numbers at some distance from the coast.
+
+   RANICEPS.--Head large, broad, and depressed; body of moderate
+   length, covered with minute scales. A separate caudal. Two
+   dorsal fins, the anterior of which is very short, rudimentary.
+   One anal fin. Ventrals composed of six rays. Cardlike teeth in
+   the jaws and on the vomer.
+
+The “Trifurcated Hake,” _R. trifurcus_, not uncommon on the coasts
+of Northern Europe.
+
+   BREGMACEROS.--Body fusiform, compressed posteriorly, covered
+   with cycloid scales of moderate size. Two dorsal fins; the
+   anterior reduced to a single long ray on the occiput; the second
+   and the anal much depressed in the middle; ventrals very long,
+   composed of five rays. Teeth small.
+
+  [Illustration: Fig. 249.--Bregmaceros macclellandii.]
+
+A dwarf Gadoid, the only one found at the surface between the Tropics.
+_B. macclellandii_ scarcely exceeds three inches in length, is not
+uncommon in the Indian Ocean, and has found its way to New Zealand;
+specimens have been picked up in mid-ocean.
+
+   MURÆNOLEPIS.--Body covered with lanceolate epidermoid
+   productions, intersecting each other at right angles like those
+   of a Freshwater-eel. Vertical fins confluent, no caudal being
+   discernible; an anterior dorsal fin is represented by a single
+   filamentous ray; ventral fins narrow, composed of several rays.
+   A barbel. Jaws with a band of villiform teeth; palate toothless.
+
+One species (_M. marmoratus_) from Kerguelen’s Land.
+
+   CHIASMODUS.--Body naked; stomach and abdomen distensible. Two
+   dorsal fins and one anal; a separate caudal; ventral fins rather
+   narrow, with several rays. Upper and lower jaws with two series
+   of large pointed teeth, some of the anterior being very large
+   and movable; teeth on the palatine bones, but none on the vomer.
+   Chin without barbel.
+
+This Gadoid (_Ch. niger_, Fig. 111, p. 311), inhabits great depths in
+the Atlantic (to 1500 fathoms). The specimen figured was taken with a
+large Scopeloid in its stomach.
+
+   BROSMIUS.--Body moderately elongate, covered with very small
+   scales. A separate caudal, one dorsal, and one anal; ventrals
+   narrow, composed of five rays. Vomerine and palatine teeth. A
+   barbel.
+
+The “Torsk” (_B. brosme_) is confined to the northern parts of the
+temperate zone, and probably extends to the arctic circle.
+
+
+                       THIRD FAMILY--OPHIDIIDÆ.
+
+_Body more or less elongate, naked, or scaly. Vertical fins generally
+united; no separate anterior dorsal or anal; dorsal occupying the
+greater portion of the back. Ventral fins rudimentary or absent,
+jugular. Gill-openings wide, the gill-membranes not attached to the
+isthmus._
+
+Marine fishes (with the exception of _Lucifuga_), partly littoral,
+partly bathybial. They may be divided into five groups.
+
+I. _Ventral fins present, attached to the humeral arch_: BROTULINA.
+
+   BROTULA.--Body elongate, covered with minute scales. Eye of
+   moderate size. Each ventral reduced to a single filament,
+   sometimes bifid at its extremity. Teeth villiform; snout with
+   barbels. One pyloric appendage.
+
+Five species of small size from the Tropical Atlantic and Indian Ocean.
+
+  [Illustration: Fig. 250.--Lucifuga dentata, from caves in Cuba.]
+
+_Lucifuga_ are _Brotula_ organised for a subterranean life. The eye
+is absent, or quite rudimentary, and covered by the skin; the barbels
+of Brotula are replaced by numerous minute ciliæ or tubercles. They
+inhabit the subterranean waters of caves in Cuba, and never come to the
+light.
+
+   BATHYNECTES.--Body produced into a long tapering tail, without
+   caudal. Mouth very wide, villiform teeth in the jaws, on the
+   vomer and palatine bones. Barbel none. Ventral fins reduced to
+   simple or bifid filaments, placed close together, and near to
+   the humeral symphysis. Gill-membranes not united; gill-laminæ
+   remarkably short. Bones of the head soft and cavernous;
+   operculum with a very feeble spine above.
+
+Deep-sea fishes, inhabiting depths varying from 1000 to 2500 fathoms.
+Three species are known, the largest specimen obtained being seventeen
+inches long.
+
+  [Illustration: Fig. 251.--Acanthonus armatus.]
+
+   ACANTHONUS.--Head large and thick, armed in front and on the
+   opercles with strong spines; trunk very short, the vent being
+   below the pectoral; tail thin, strongly compressed, tapering,
+   without caudal. Eye small. Mouth very wide; villiform teeth
+   in the jaws, on the vomer and palatine bones. Barbel none.
+   Ventrals reduced to simple filaments placed close together on
+   the humeral symphysis. Scales extremely small. Bones of the head
+   soft.
+
+Only two specimens, thirteen inches long, of this remarkable deep-sea
+form have been obtained, at a depth of 1075 fathoms, in the Indian
+Ocean.
+
+   TYPHLONUS.--Head large, compressed, with most of the bones in
+   a cartilaginous condition; the superficial bones with large
+   muciferous cavities, not armed. Snout a thick protuberance
+   projecting beyond the mouth, which is rather small and inferior.
+   Trunk very short, the vent being below the pectoral; tail thin,
+   strongly compressed, tapering, without separate caudal. Eye
+   externally not visible. Villiform teeth in the jaws, on the
+   vomer and palatine bones. Barbel none. Scales thin, deciduous,
+   small.
+
+Also of this deep-sea fish two specimens only are known, 10 inches
+long, from a depth of 2200 fathoms in the Western Pacific.
+
+   APHYONUS.--Head, body, and tapering tail strongly compressed,
+   enveloped in a thin, scaleless, loose skin. Vent far behind
+   the pectoral. Snout swollen, projecting beyond the wide
+   mouth. No teeth in the upper jaw, small ones in the lower. No
+   externally visible eye. Barbel none. Head covered with a system
+   of wide muciferous channels, the dermal bones being almost
+   membranaceous, whilst the others are in a semi-cartilaginous
+   condition. Notochord persistent, but with a superficial
+   indication of vertebral segments.
+
+  [Illustration: Fig. 252.--Aphyonus gelatinosus.]
+
+One specimen only of this most remarkable form is known; it is 5½
+inches long, and was obtained at a depth of 1400 fathoms south of New
+Guinea.
+
+Of the remaining genera belonging to this group, _Brotulophis_,
+_Halidesmus_, _Dinematichthys_, and _Bythites_ are surface forms;
+_Sirembo_ and _Pteridium_ inhabit moderate depths; _Rhinonus_ is a
+deep-sea fish.
+
+II. _Ventral fins replaced by a pair of bifid filaments (barbels)
+inserted below the glossohyal_: OPHIDIINÆ.
+
+   OPHIDIUM.--Body elongate, compressed, covered with very small
+   scales. Eye of moderate size. All the teeth small.
+
+Small fishes from the Atlantic and Pacific. Seven species are known,
+differing from one another in the structure of the air-bladder (see p.
+145).
+
+   GENYPTERUS is a larger form of _Ophidium_, in which the outer
+   series of teeth in the jaws and the single palatine series
+   contains strong teeth.
+
+Three species from the Cape of Good Hope, South Australia, New Zealand,
+and Chili are known. They grow to a length of five feet, and have an
+excellent flesh, like cod, well adapted for curing. At the Cape they
+are known by the name of “Klipvisch,” and in New Zealand as “Ling” or
+“Cloudy Bay Cod.”
+
+III. _No ventral fins whatever; vent at the throat_: FIERASFERINA.
+
+These fishes (_Fierasfer_ and _Encheliophis_) are of very small
+size and eel-like in shape; the ten species known are found in the
+Mediterranean, Atlantic, and Indo-Pacific. As far as is known they
+live parasitically in cavities of other marine animals, accompany
+Medusæ, and more especially penetrate into the respiratory cavities of
+Star-fishes and Holothurians. Not rarely they attempt other animals
+less suited for their habits, as, for instance, Bivalves; and cases are
+known in which they have been found imprisoned below the mantle of the
+Mollusk, or covered over with a layer of the pearly substance secreted
+by it. They are perfectly harmless to their host, and merely seek for
+themselves a safe habitation, feeding on the animalcules which enter
+with the water the cavity inhabited by them.
+
+IV. _No ventral fins whatever; vent remote from the head; gill-openings
+very wide, the gill-membranes not being united_: AMMODYTINA.
+
+The “Sand-eels” or “Launces” (_Ammodytes_) are extremely common on
+sandy shores of Europe and North America. They live in large shoals,
+rising as with one accord to the surface, or diving to the bottom,
+where they bury themselves with incredible rapidity in the sand.
+They are much sought after for bait by fishermen, who discover their
+presence on the surface by watching the action of Porpoises which
+feed on them. These Cetaceans, when they meet with a shoal, know how
+to keep it on the surface by diving below and swimming round it, thus
+destroying large numbers of them. The most common species on the
+British coast is the Lesser Sand-eel (_A. tobianus_); the Greater
+Sand-eel (_A. lanceolatus_), which attains to a length of eighteen
+inches; _A. siculus_, from the Mediterranean, scarcer in British seas.
+Two species live on the American coasts, _A. americanus_ and _A.
+dubius_; one in California, _A. personatus_. _Bleekeria_ from Madras is
+the second genus of this group.
+
+  [Illustration: Fig. 253.--Congrogadus subducens.]
+
+V. _No ventral fins whatever; vent remote from the head; gill-openings
+of moderate width, the gill-membranes being united below the throat,
+not attached to the isthmus_: CONGROGADINA.
+
+Only two fishes belong to this group--_Congrogadus_ from the Australian
+coasts, and _Haliophis_ from the Red Sea.
+
+
+                       FOURTH FAMILY--MACRURIDÆ.
+
+_Body terminating in a long, compressed, tapering tail, covered with
+spiny, keeled, or striated scales. One short ante__rior dorsal; the
+second very long, continued to the end of the tail, and composed of
+very feeble rays; anal of an extent similar to that of the second
+dorsal; no caudal. Ventral fins thoracic or jugular, composed of
+several rays._
+
+  [Illustration: Fig. 254.--Scale of Macrurus trachyrhynchus.]
+
+  [Illustration: Fig. 255.--Scale of Macrurus cœlorhynchus.]
+
+  [Illustration: Fig. 256.--Scale from the lateral line of Macrurus
+  australis.]
+
+This family, known a few years ago from a limited number of examples,
+representing a few species only, proves to be one which is distributed
+over all oceans, occurring in considerable variety and great abundance
+at depths of from 120 to 2600 fathoms. They are, in fact, Deep-sea
+Gadoids, much resembling each other in the general shape of their body,
+but differing in the form of the snout and in the structure of their
+scales. About forty species are known, of which many attain a length of
+three feet. They have been referred to the following genera:--
+
+  [Illustration: Fig. 257.--Macrurus australis.]
+
+   MACRURUS.--Scales of moderate size; snout produced, conical;
+   mouth inferior.
+
+   CORYPHÆNOIDES.--Scales of moderate size; snout obtuse, obliquely
+   truncated; cleft of the mouth lateral.
+
+   MACRURONUS.--Scales of moderate size, spiny; snout pointed;
+   mouth anterior and lateral, with the lower jaw projecting.
+
+   MALACOCEPHALUS.--Scales very small, ctenoid; snout short,
+   obtuse, obliquely truncated.
+
+   BATHYGADUS.--Scales small, cycloid; snout not projecting beyond
+   the mouth; mouth wide, anterior, and lateral.
+
+_Ateleopus_ from Japan and _Xenocephalus_ from New Ireland are genera
+belonging to the Gadoid Anacanths, but are very imperfectly known.
+
+
+             SECOND DIVISION--ANACANTHINI PLEURONECTOIDEI.
+
+_Head and part of the body unsymmetrically formed._
+
+This division consists of one family only:
+
+
+                            PLEURONECTIDÆ.
+
+The fishes of this family are called “Flat-fishes,” from their strongly
+compressed, high, and flat body; in consequence of the absence of
+an air-bladder, and of the structure of their paired fins, they are
+unable to maintain their body in a vertical position, resting and
+moving on one side of the body only. The side turned towards the
+bottom is sometimes the left, sometimes the right, colourless, and
+termed the “blind” side; that turned upwards and towards the light
+is variously, and in some tropical species even vividly, coloured.
+Both eyes are on the coloured side, on which side also the muscles
+are more strongly developed. The dorsal and anal fins are exceedingly
+long, without division. All the Flat-fishes undergo remarkable
+changes with age, which, however, are very imperfectly known and not
+yet fully understood, from the difficulty of referring larval forms
+to their respective parents. The larvæ are, singularly enough, much
+more frequently met in the open ocean than near the coast; they are
+transparent, like _Leptocephali_; perfectly symmetrical, with an
+eye on each side of the head, and swim in a vertical position like
+other fishes. The manner in which one eye is transferred from the blind
+to the coloured side is subject to discussion. Whilst some naturalists
+believe that the eye turning round its axis pushes its way through the
+yielding bones from the blind to the upper side, others hold that, as
+soon as the body of the fish commences to rest on one side only, the
+eye of that side, in its tendency to turn towards the light, carries
+the surrounding parts of the head with it; in fact, the whole of the
+fore-part of the head is twisted towards the coloured side, which is a
+process of but little difficulty as long as the framework of the head
+is still cartilaginous.
+
+Flat-fishes when adult live always on the bottom, and swim with an
+undulating motion of their body. Sometimes they rise to the surface;
+they prefer sandy bottom, and do not descend to any considerable depth.
+They occur in all seas, except in the highest latitudes and on rocky,
+precipitous coasts, becoming most numerous towards the equator; those
+of the largest size occur in the temperate zone. Some enter fresh water
+freely, and others have become entirely acclimatised in ponds and
+rivers. All are carnivorous.
+
+Flat-fishes were not abundant in the tertiary epoch; the only
+representative known is a species of _Rhombus_ from Monte Bolca.
+
+The size and abundance of Flat-fishes, and the flavour of the flesh of
+the majority of the species, render this family one of the most useful
+to man; and especially on the coasts of the northern temperate zone,
+their capture is one of the most important sources of profit to the
+fishermen.
+
+   PSETTODES.--Mouth very wide, the maxillary being more than
+   one-half of that of the head. Each jaw armed with two series of
+   long, slender, curved, distant teeth, the front teeth of the
+   inner series of the lower jaw being the longest, and received
+   in a groove before the vomer; vomerine and palatine teeth. The
+   dorsal fin commences on the nape of the neck.
+
+This genus fitly heads the list of Flat-fishes, having retained more
+of symmetrical structure than the other members of the family, and,
+therefore, their eyes are as often found on the right as on the left
+side. It seems to swim, not unfrequently, in a vertical position. Only
+one species is known, _Ps. erumei_, common in the Indian Ocean.
+
+   HIPPOGLOSSUS.--Eyes on the right side; mouth wide, the length of
+   the maxillary being one-third of that of the head. Teeth in the
+   upper jaw in a double series; the anterior of the upper jaw and
+   the lateral of the lower strong. The dorsal fin commences above
+   the eye.
+
+The “Holibut” (_H. vulgaris_) is the largest of all Flat-fishes,
+attaining to a length of five and six feet, and a weight of several
+hundredweights. It is found along the northern coasts of Europe, on the
+coasts of Kamtschatka and California, particularly frequenting banks
+situated at some distance from the coast, and at a depth of 50 to 120
+fathoms.
+
+Other genera, with nearly symmetrical mouth, in which the dorsal fin
+commences above the eye, are _Hippoglossoides_ (the “Rough Dab”) and
+_Tephritis_.
+
+   RHOMBUS.--Eyes on the left side. Mouth wide, the length of the
+   maxillary being more than one-third of that of the head. Each
+   jaw with a band of villiform teeth, without canines; vomerine
+   teeth, none on the palatines. The dorsal fin commences on the
+   snout. Scales none or small.
+
+Seven species from the North Atlantic and Mediterranean, of which the
+most noteworthy are the “Turbot,” _Rh. maximus_, one of the most valued
+food-fishes, and growing to a length of three feet; the “Turbot of the
+Black Sea,” _Rh. mæoticus_, the body of which is covered with bony,
+conical tubercles, which are as large as the eye; the “Brill,” _Rh.
+lævis_, represented on the North American coasts by _Rh. aquosus_; the
+“Whiff,” or “Mary-sole,” or “Sail-fluke,” _Rh. megastoma_; “Bloch’s
+Top-knot,” _Rh. punctatus_ (described by Yarrell as _Rh. hirtus_, and
+often confounded with the following species).
+
+PHRYNORHOMBUS, differing from _Rhombus_ in lacking vomerine teeth. The
+scales are very small and spiny.
+
+The “Top-knot” (_Ph. unimaculatus_) occurs occasionally on the south
+coast of England, and is more common in the Mediterranean; it is a
+small species.
+
+   ARNOGLOSSUS.--Mouth wide, the length of the maxillary being
+   more or not much less than one-third of that of the head. Teeth
+   minute, in a single series in both jaws; vomerine or palatine
+   teeth none. The dorsal fin commences on the snout. Scales of
+   moderate size, deciduous; lateral line with a strong curve above
+   the pectoral. Eyes on the left side.
+
+Seven species from European and Indian Seas. The “Scald-fish” (_A.
+laterna_) is common in the Mediterranean, and extends to the south
+coast of England; it is a small species.
+
+   PSEUDORHOMBUS.--Mouth wide, the length of the maxillary being
+   more than one-third of that of the head. Teeth in both jaws in a
+   single series, of unequal size; vomerine or palatine teeth none.
+   The dorsal fin commences on the snout. Scales small; lateral
+   line with a strong curve anteriorly. Eyes on the left side.
+   Interorbital space not concave.
+
+A tropical genus with a few outlying species, represented chiefly in
+the Indo-Pacific, and also in the Atlantic. Seventeen species.
+
+   RHOMBOIDICHTHYS.--Mouth of moderate width or small. Teeth
+   minute, in a single or double series; vomerine or palatine teeth
+   none. Eyes separated by a concave more or less broad space. The
+   dorsal fin commences on the snout. Scales ciliated; lateral line
+   with a strong curve anteriorly. Eyes on the left side.
+
+A tropical genus, but also represented in the Mediterranean and on the
+coast of Japan. Sixteen species, the majority of which are prettily
+coloured and ornamented with ocellated spots; in some species the adult
+males have some of the fin-rays prolonged into filaments.
+
+Other genera with nearly symmetrical mouth, in which the dorsal fin
+commences before the eye, on the snout, are _Citharus_, _Anticitharus_,
+_Brachypleura_, _Samaris_, _Psettichthys_, _Citharichthys_,
+_Hemirhombus_, _Paralichthys_, _Liopsetta_, _Lophonectes_,
+_Lepidopsetta_, and _Thysanopsetta_.
+
+   PLEURONECTES.--Cleft of the mouth narrow, with the dentition
+   much more developed on the blind side than on the coloured.
+   Teeth in a single or in a double series, of moderate size;
+   palatine and vomerine teeth none. The dorsal fin commences above
+   the eye. Scales very small or entirely absent. Eyes generally on
+   the right side.
+
+This genus is characteristic of the littoral fauna of the northern
+temperate zone, a few species ranging to the Arctic circle.
+Twenty-three species are known, of which the following are the most
+noteworthy: _P. platessa_, the “Plaice,” ranging from the coast of
+France to Iceland; _P. glacialis_, from the Arctic coasts of North
+America; _P. americanus_, the transatlantic representative of the
+Plaice; _P. limanda_, the common “Dab;” _P. microcephalus_, the
+“Smear-dab;” _P. cynoglossus_, the “Craig-fluke;” _P. flesus_, the
+“Flounder.”
+
+   RHOMBOSOLEA.--Eyes on the right side, the lower in advance of
+   the upper. Mouth narrower on the right side than on the left;
+   teeth on the blind side only, villiform; palatine and vomerine
+   teeth none. The dorsal fin commences on the foremost part of
+   the snout. Only one ventral which is continuous with the anal.
+   Scales very small, cycloid; lateral line straight.
+
+This genus represents _Pleuronectes_ in the Southern Hemisphere, but
+consists of three species only, which occur on the coasts of New
+Zealand, and are valued as food-fishes.
+
+Other genera, with narrow unsymmetrical mouth, in which the upper eye
+is not in advance of the lower, and which have pectoral fins, are
+_Parophrys_, _Psammodiscus_, _Ammotretis_, _Peltorhamphus_, _Nematops_,
+_Læops_, and _Poecilopsetta_.
+
+   SOLEA.--Eyes on the right side, the upper being more or less
+   in advance of the lower. Cleft of the mouth narrow, twisted
+   round to the left side. Villiform teeth on the blind side only;
+   vomerine or palatine teeth none. The dorsal fin commences on the
+   snout, and is not confluent with the caudal. Scales very small,
+   ctenoid; lateral line straight.
+
+“Soles” are numerously represented in all suitable localities within
+the temperate and tropical zones, with the exception of the southern
+parts of the southern temperate zone, in which they are absent.
+Some enter or live in fresh water. Nearly forty species are known.
+British are _S. vulgaris_, the common “Sole;” _S. aurantiaca_, the
+“Lemon-sole,” which is rather a southern species, and inhabits, on
+the south coast of England, deeper water than the common Sole; _S.
+variegata_, the “Banded Sole,” with very small pectoral fins; and _S.
+minuta_, the “Dwarf-Sole.”--Allied to _Solea_ are _Pardachirus_ and
+_Liachirus_ from the Indian coasts.
+
+   SYNAPTURA.--Eyes on the right side, the upper in advance of
+   the lower. Cleft of the mouth narrow, twisted round to the
+   left side; minute teeth on the left side only. Vertical fins
+   confluent. Scales small, ctenoid; lateral line straight.
+
+Twenty species; with the exception of two from the Mediterranean
+and coast of Portugal, all belong to the fauna of the Indian
+Ocean.--Closely allied is _Aesopia_.
+
+   GYMNACHIRUS.--Mouth very small, toothless. Scales none, lateral
+   line straight. Eyes on the right side. The dorsal fin commences
+   on the snout; caudal free. Pectorals rudimentary or entirely
+   absent.
+
+Two species from the Tropical Atlantic.
+
+   CYNOGLOSSUS.--Eyes on the left side; pectorals none; vertical
+   fins confluent. Scales ctenoid; lateral line on the left side
+   double or triple; upper part of the snout produced backwards
+   into a hook; mouth unsymmetrical, rather narrow. Teeth minute,
+   on the right side only.
+
+Abundant in the Indian seas, and especially on the flat sandy shores
+of China. About thirty-five species are known, which rarely exceed a
+length of eighteen inches. They are easily recognised by their long
+narrow shape (which has been compared to a dog’s tongue) and the
+peculiar form of their snout.
+
+   To complete the list of Pleuronectoid genera, the following
+   have to be mentioned: _Soleotalpa_ and _Apionichthys_, Soles
+   with rudimentary eyes; _Ammopleurops_, _Aphoristia_, and
+   _Plagusia_, which are closely allied to _Cynoglossus_, the
+   latter genus having the lips provided with tentacles.
+
+
+                       FOURTH ORDER--PHYSOSTOMI.
+
+_All the fin-rays articulated, only the first of the dorsal and
+pectoral fins is sometimes ossified. Ventral fins, if present,
+abdominal, without spine. Air-bladder, if present, with a pneumatic
+duct (except in Scombresocidæ)._
+
+
+                        FIRST FAMILY--SILURIDÆ.
+
+_Skin naked or with osseous scutes, but without scales. Barbels
+always present; maxillary bone rudimentary, almost always forming a
+support to a maxillary barbel. Margin of the upper jaw formed by the
+intermaxillaries only. Suboperculum absent. Air-bladder generally
+present, communicating with the organ of hearing by means of the
+auditory ossicles. Adipose fin present or absent._
+
+A large family, represented by numerous genera, which exhibit a great
+variety of form and structure of the fins; they inhabit the fresh
+waters of all the temperate and tropical regions; a few enter the sea
+but keep near the coast. The first appearance of Siluroids is indicated
+by some fossil remains in tertiary deposits of the highlands of Padang
+in Sumatra, where _Pseudeutropius_ and _Bagarius_, types well
+represented in the living Indian fauna, have been found. Also in North
+America spines referable to Cat-fishes have been found in tertiary
+formations.
+
+The skeleton of the typical Siluroids shows many peculiarities. The
+cranial cavity is not membranous on the sides, but closed as in the
+Cyprinidæ, by the orbitosphenoids and the ethmoid that unite with
+the prefrontals, carrying forward the cranial cavity to the nasal
+bone, without leaving a membranous septum between the orbits. But the
+supraoccipital is greatly developed, and in many the post-temporal is
+united by suture to the sides of the cranium. In numerous members of
+the family the skull is enlarged posteriorly, by dermal ossifications,
+to form a kind of helmet which spreads over the nape; the lateral
+angles of this production are formed by the suprascapulæ, augmented
+and fixed by suture, and the median part is the extension of the
+supraoccipital, which is generally very large, is connected anteriorly
+with the frontal, and passing backwards between the postfrontals, the
+parietals, the mastoids, and the suprascapulæ, goes past them all on
+to the nape. The mastoids interpose between the postfrontals and the
+parietals, so as to come in contact with the supraoccipital, and the
+parietals but little developed are pressed to the back part of the
+cranium, and in some instances wholly disappear.
+
+The suprascapula most frequently unites to the mastoid by an immovable
+suture, which includes the parietal when that bone is present, and
+extends even to the supraoccipital. It gives out besides two processes,
+one of them resting on the exoccipital and basi-occipital, or wedging
+itself between them, and the other going to the first vertebra;
+sometimes a plate from the exoccipital supports the same vertebra. This
+vertebra, though it presents a pretty continuous centrum beneath, is in
+reality composed of three or four coalescent vertebræ, as we ascertain
+by its diapophyses, by the circular elevations of the neural canal, and
+by the holes for the exit of the pairs of spinal nerves. There is great
+variety in the development of the various processes of the bones we
+have mentioned, and there is no less in the magnitude and connections
+of the first three interneurals.
+
+In general in the species which have a strong dorsal spine the second
+and third interneurals unite to form a single plate, the “buckler;” the
+great spine is articulated to the third interneural, and there is only
+the vestige of a spine on the second interneural in form of a small
+oval bone, forked below, whose function is to act as a bolt or fulcrum
+to the great spine when the fish wishes to use it as an offensive
+weapon. The great spine itself is joined by a ring to a second spine,
+which belongs to the third interneural. This articulation by ring
+exists in Lophius and a few other fishes not of this family.
+
+The first interneural does not carry a ray, and it varies much in
+the species whose helmet is continuous with the buckler, as in
+many of the Bagri and Pimelodi. In these cases the supraoccipital,
+extending backwards, conceals the first interneural, passing over it
+to touch with its point the buckler formed by the second and third
+interneurals. In other instances, as in Synodontis and Auchenipterus,
+the supraoccipital and second interneural, forking and expanding,
+inclose and join themselves to the first interneural, but leave a
+larger or smaller space in the middle of the nuchal armour which they
+contribute to form. When the point of the supraoccipital does not reach
+quite to the second interneural, the first interneural remains free
+from connection, and occasionally shows as a narrow plate interposed
+between the other two; in such a case the helmet is not continuous with
+the buckler.
+
+The neural spines of the coalescent centra, which form the
+apparently single first vertebra, concur also in sustaining the
+nuchal plate-armour and the first great dorsal spine. They carry the
+interneurals, are joined to them by suture, and one of them is often
+inclined towards the occiput to assist in sustaining the head; in fact,
+this part of the skeleton is constructed to give firm mutual support.
+
+The shoulder-girdle of the Siluroids is also formed to give
+resistance to the strong weapon with which it is frequently armed. The
+post-temporal, as we have said above, is often united by suture to the
+cranium, and it obtains support below by one or two processes that
+are fixed on the basioccipitals and on the diapophysis of the first
+vertebra.
+
+In most osseous fishes the clavicle completes the lower key of the
+scapular arch in joining its fellow by suture or synchondrosis without
+the intervention of the coracoid; but in the Siluroids the coracoid
+descends to take part in this joint, and sometimes even to occupy the
+half of the suture, which is not unfrequently constructed of very deep
+interlocking serratures. The solidity of this base of the pectoral
+spine is further augmented by the intimate union of the coracoid
+and scapula, which often extends to junction by suture, or even to
+coalescence; and these bones, moreover, give off two bony arches--the
+first a slender one, arising from the salient edge of the coracoid
+near the pectoral fin, and going to the interior face of the scapular
+that is applied to the interior surface of the ascending branch of the
+clavicle; the second and broader supplementary arch is often perforated
+by a large hole; it also emanates from the same salient edge of the
+radius, but proceeds in opposite direction to the inferior edge of the
+clavicle, a little before the insertion of the pectoral spine. The two
+arches give attachments to the muscles that move this spine; in the
+Synodontes and many Bagri the upper arch remains in a cartilaginous or
+ligamentous condition, while in Malapterurus it is the lower arch that
+does not ossify, but both are fully formed in the Siluri and many other
+Siluroids more closely allied to that typical genus. The postclavicle
+is also wanting in the Siluroids. The pterygoid and entopterygoid are
+reduced to a single bone, the symplectic is wholly wanting, and the
+palatine is merely a slender cylindrical bone. The sub-operculum is
+likewise constantly absent in all the Siluroids.
+
+The great number of different generic types has necessitated a further
+division of this family into eight subdivisions:
+
+I. SILURIDÆ HOMALOPTERÆ.--_The dorsal and anal fins are very long,
+nearly equal in extent to the corresponding parts of the vertebral
+column._
+
+
+                            _a_. CLARIINA.
+
+   CLARIAS.--Dorsal fin extending from the neck to the caudal,
+   without adipose division. Cleft of the mouth transverse,
+   anterior, of moderate width; barbels eight; one pair of nasal,
+   one of maxillary, and two pairs of mandibulary barbels. Eyes
+   small. Head depressed; its upper and lateral parts are osseous,
+   or covered with only a very thin skin. A dendritic accessory
+   branchial organ is attached to the convex side of the second and
+   fourth branchial arches, and received in a cavity behind the
+   gill-cavity proper. Ventrals six-rayed; only the pectoral has a
+   pungent spine. Body eel-like.
+
+Twenty species from Africa, the East Indies, and the intermediate parts
+of Asia; some attain to a length of six feet. They inhabit muddy and
+marshy waters; the physiological function of the accessory branchial
+organ is not known. Its skeleton is formed by a soft cartilaginous
+substance covered by mucous membrane, in which the vessels are
+imbedded. The vessels arise from branchial arteries, and return the
+blood into branchial veins. The vernacular name of the Nilotic species
+is “Carmoot.”
+
+   HETEROBRANCHUS differs from _Clarias_ only in the structure of
+   the dorsal fin, the posterior portion of which is adipose.
+
+The geographical range of this genus is not quite co-extensive with
+that of _Clarias_, inasmuch as it is limited to Africa and the
+East-Indian Archipelago. Six species.
+
+
+                            _b_. PLOTOSINA.
+
+   PLOTOSUS.--A short dorsal fin in front, with a pungent spine; a
+   second long dorsal coalesces with the caudal and anal. Vomerine
+   teeth molar-like. Barbels eight or ten; one immediately before
+   the posterior nostril, which is remote from the anterior, the
+   latter being quite in front of the snout. Cleft of the mouth
+   transverse. Eyes small. The gill-membranes are not confluent
+   with the skin of the isthmus. Ventral fins many-rayed. Head
+   depressed; body elongate.
+
+  [Illustration: Fig. 258.--Mouth of Cnidoglanis megastoma,
+  Australia.]
+
+Three species are known from brackish waters of the Indian Ocean freely
+entering the sea. _Plotosus anguillaris_ is distinguished by two white
+longitudinal bands, and is one of the most generally distributed
+and common Indian fishes.--_Copidoglanis_ and _Cnidoglanis_ are two
+very closely allied forms, chiefly from rivers and brackish waters
+of Australia. None of these Siluroids attain to a considerable size.
+_Chaca_, from the East Indies, belongs likewise to this sub-family.
+
+  [Illustration: Fig. 259.--Cnidoglanis microcephalus.]
+
+II. SILURIDÆ HETEROPTERÆ.--_The rayed dorsal fin is very little
+developed, and, if it is present, it belongs to the abdominal portion
+of the vertebral column; the adipose fin is exceedingly small or
+absent. The extent of the anal is not much inferior to that of the
+caudal vertebral column. The gill-membranes overlap the isthmus,
+remaining more or less separate_: SILURINA.
+
+   SACCOBRANCHUS.--Adipose fin none; dorsal very short, without
+   pungent spine, placed above the ventrals. Cleft of the mouth
+   transverse, anterior, of moderate width; barbels eight. Eyes
+   rather small. The upper and lateral parts of the head osseous
+   or covered with a very thin skin. Gill-cavity with an accessory
+   posterior sac, extending backwards between the muscles along
+   each side of the abdominal and caudal portions of the vertebral
+   column. Ventrals six-rayed.
+
+Small fishes from East Indian rivers; four species are known. The
+lung-like extension of the branchial cavity receives water, and is
+surrounded by contractile transverse muscular fibres by which the water
+is expelled at intervals. The vessels of the sac take their origin in
+the last branchial artery, and pass into the aorta.
+
+   SILURUS.--No adipose fin; one very short dorsal, without pungent
+   spine. Barbels four or six, one to each maxillary, and one or
+   two to each mandible. Nostrils remote from each other. Head
+   and body covered with soft skin. The eye is situated above the
+   level of the angle of the mouth. The dorsal fin is anterior to
+   the ventrals which are composed of more than eight rays. Caudal
+   rounded.
+
+This genus, of which five species are known, inhabits the temperate
+parts of Europe and Asia. The species which has given the name to
+the whole family, is the “Wels” of the Germans, _Silurus glanis_. It
+is found in the fresh waters east of the Rhine, and is, besides the
+Sturgeons, the largest of European Freshwater-fishes, and the only
+species of this family which occurs in Europe. Barbels six. It attains
+to a weight of 300 or 400 lbs., and the flesh, especially of smaller
+specimens, is firm, flaky, and well flavoured. Aristotle described
+it under the name of _Glanis_. Its former occurrence in Scotland has
+justly been denied. In China it is represented by a similar species,
+_S. asotus_, which, however, has four barbels only.
+
+  [Illustration: Fig. 260.--The “Wels,” Siluris glanis.]
+
+This sub-family is well represented by various other genera in the
+fresh waters of the African as well as Indian region. African genera
+are _Schilbe_ and _Eutropius_; East Indian: _Silurichthys_, _Wallago_,
+_Belodontichthys_, _Eutropiichthys_, _Cryptopterus_, _Callichrous_,
+_Hemisilurus_, _Siluranodon_, _Ailia_, _Schilbichthys_, _Lais_,
+_Pseudeutropius_, _Pangasius_, _Helicophagus_, and _Silondia_.
+
+III. SILURIDÆ ANOMALOPTERÆ.--_Dorsal and adipose fins very short,
+the former belonging to the caudal vertebral column; anal very long.
+Ventrals in front of the dorsal. Gill-membranes entirely separate,
+overlapping the isthmus_: (HYPOPHTHALMINA.)
+
+   HYPOPHTHALMUS.--Dorsal fin with seven rays, the first of which
+   is slightly spinous. The lower jaw is rather the longer. Barbels
+   six, those of the mandible long. No teeth; intermaxillaries very
+   feeble. Head covered with skin. Eye of moderate size, situated
+   behind and below the angle of the mouth. Ventrals small,
+   six-rayed.
+
+Four species from tropical America. The second genus of this sub-family
+is _Helogenes_ from the Essequibo.
+
+
+IV. SILURIDÆ PROTEROPTERÆ.--_The rayed dorsal fin is always present,
+short, with not more than twelve short rays, and belongs to the
+abdominal portion of the vertebral column, being placed in advance of
+the ventrals. The adipose fin is always present and well developed,
+although frequently short. The extent of the anal is much inferior
+to that of the caudal vertebral column. The gill-membranes are not
+confluent with the skin of the isthmus, their posterior margin always
+remaining free even if they are united with each other. Whenever the
+nasal barbel is present it belongs to the posterior nostril._
+
+
+                             _a._ BAGRINA.
+
+   BAGRUS.--Adipose fin long; a short dorsal with a pungent spine
+   and nine or ten soft rays; anal fin short, with less than twenty
+   rays. Barbels eight. The anterior and posterior nostrils are
+   remote from each other, the posterior being provided with a
+   barbel. Teeth on the palate in a continuous band. Eyes with a
+   free orbital margin. Caudal forked; ventrals six-rayed.
+
+This genus consists of two species only, common in the Nile, viz.
+the “Bayad,” _B. bayad_, and _B. docmac_. Both grow to a large size,
+exceeding a length of five feet, and are eaten. _Chrysichthys_ and
+_Clarotes_ are two other Siluroid genera from African rivers, closely
+allied to Bagrus. Similar Siluroids are common in the East Indies, and
+have been referred to the following genera: _Macrones_, _Pseudobagrus_,
+_Liocassis_, _Bagroides_, _Bagrichthys_, _Rita_, _Acrochordonichthys_,
+_Akysis_.
+
+
+                            _b._ AMIURINA.
+
+   AMIURUS.--Adipose fin of moderate length; a short dorsal with a
+   pungent spine and six soft rays; anal fin of moderate length.
+   Barbels eight. The anterior and posterior nostrils are remote
+   from each other, the posterior being provided with a barbel.
+   Palate edentulous. Head covered with skin above. Ventrals
+   eight-rayed.
+
+The “Cat-fishes” of North America, of which about a dozen different
+species are known. One species occurs in China. Allied, but smaller
+forms are _Hopladelus_ and _Noturus_, likewise from North
+America.
+
+
+                           _c_. PIMELODINA.
+
+   PLATYSTOMA.--Adipose fin of moderate length; a short dorsal fin
+   with a pungent spine and six or seven soft rays; anal fin rather
+   short. Snout very long, spatulate, with the upper jaw more or
+   less projecting; the upper surface of the head not covered by
+   the skin. Barbels six; the anterior and posterior nostrils
+   remote from each other, none with a barbel. Palate toothed.
+   Caudal forked; ventrals six-rayed, inserted behind the dorsal.
+
+Twelve species from South America, some attaining a length of six feet,
+the majority being ornamented with deep-black spots or bands. Allied
+genera from South America, likewise distinguished by a long spatulate
+snout, are _Sorubim_, _Hemisorubim_, and _Platystomatichthys_, whilst
+_Phractocephalus_, _Piramutana_, _Platynematichthys_, _Piratinga_,
+_Bagropsis_, and _Sciades_, have a snout of ordinary length. The
+barbels of some are of extraordinary length, and not rarely dilated and
+band-like.
+
+   PIMELODUS.--Adipose fin well developed; dorsal fin short, with a
+   more or less pungent spine and six rays; anal fin short. Barbels
+   six, cylindrical or slightly compressed, none of them belonging
+   to either of the nostrils, which are remote from each other.
+   Palate edentulous. Ventrals six-rayed, inserted behind the
+   dorsal.
+
+Of all South American genera this is represented by the greatest
+number of species, more than forty being well characterised; they
+differ chiefly with regard to the length of the adipose fin and
+barbels, and the strength of the dorsal spine. Singularly, two species
+(_P. platychir_ and _P. balayi_), are found in West Africa. The
+majority are of but moderate size and plain coloration.--Allied South
+American genera (also without teeth on the palate), are _Pirinampus_,
+_Conorhynchus_, _Notoglanis_, _Callophysus_, _Lophiosilurus_.
+
+   AUCHENOGLANIS.--Adipose fin rather long, dorsal short, with
+   a pungent spine and seven rays; anal short. Snout produced,
+   pointed, with narrow mouth. Barbels six, none of which belongs
+   to either of the nostrils, which are remote from each other. The
+   teeth of each jaw form a pair of small elliptic patches which
+   are longer than broad; palate edentulous. Eyes of moderate size.
+   Ventrals six-rayed.
+
+One species, _Au. biscutatus_, from the Nile, Senegal, and other
+West African rivers.
+
+
+                             _d._ ARIINA.
+
+   ARIUS.--Adipose fin of moderate length or short; a short dorsal
+   fin with a pungent spine and seven soft rays; anal fin rather
+   short. Head osseous above; barbels six, four at the mandible,
+   none at either of the nostrils which are close together.
+   Eyes with a free orbital margin. Caudal fin forked; ventrals
+   six-rayed, behind the dorsal.
+
+Of all Siluroid genera this has the greatest number of species (about
+seventy), and the widest distribution, being represented in almost
+all tropical countries which are drained by large rivers; some of
+the species prefer brackish to fresh water, and a few enter the
+sea, but keep near to the coast. Some of the species are of small
+size, whilst others exceed a length of five feet. The extent of the
+armature of the neck and the dentition vary much in the different
+species, and affords two of the principal characters by which the
+species are separated.--The following genera are allied to _Arius_,
+_Galeichthys_ from South Africa; _Genidens_ and _Paradiplomystax_ from
+Brazil; _Diplomystax_ from Chile; _Aelurichthys_ from Central and
+South America; _Hemipimelodus_, _Ketengus_, _Osteo__geniosus_, and
+_Batrachocephalus_ from the East Indies; and _Atopochilus_ from West
+Africa.
+
+  [Illustration: Fig. 261.--Arius australis, from Queensland.]
+
+
+                            _e._ BAGARIINA.
+
+   BAGARIUS.--Adipose fin rather short; a short dorsal with one
+   spine and six rays; anal fin of moderate length. Barbels eight,
+   of which one pair stands between the anterior and posterior
+   nostrils which are close together. Head naked above. Caudal fin
+   deeply forked; ventrals rays six. Thorax without longitudinal
+   plaits of the skin.
+
+A large Siluroid (_B. bagarius_) from rivers of India and Java;
+exceeding a length of six feet.
+
+  [Illustration: Fig. 262.--Euglyptosternum coum, thoracic adhesive
+  apparatus.]
+
+   EUGLYPTOSTERNUM.--Adipose fin of moderate length; a short
+   dorsal with a pungent spine and six rays; anal fin short.
+   Barbels eight, of which one pair is placed between the anterior
+   and posterior nostrils which are close together. Teeth on the
+   palate villiform, in two separate patches. Eyes small, below the
+   skin. Caudal forked; ventral rays six. Pectorals horizontal,
+   with a thoracic adhesive apparatus between, which is formed by
+   longitudinal plaits of the skin.
+
+This fish (_Eu. coum_) inhabits the river Coic in Syria, and is about
+twelve inches long. The plaited structure on the thorax probably
+increases the capability of the fish of maintaining its position
+in the rapid current of the stream, a function which appears to be
+chiefly performed by the horizontally expanded pectoral fins. A similar
+structure is found in _Glyptosternum_, a genus represented by eight
+species in mountain streams of the East Indies, and differing from the
+Syrian species in lacking the teeth on the palate.
+
+V. SILURIDÆ STENOBRANCHIÆ.--_The rayed dorsal fin is short, if
+present, belonging to the abdominal portion of the vertebral column,
+the ventrals being inserted behind it (except in Rhinoglanis). The
+gill-membranes are confluent with the skin of the isthmus._
+
+
+                            _a_. DORADINA.
+
+Some of the genera have no bony shields along the lateral line,
+and a small adipose fin or none whatever; all of these are
+South American--_Ageniosus_, _Tetranematichthys_, _Euanemus_,
+_Auchenipterus_, _Glanidium_, _Centromochlus_, _Trachelyopterus_,
+_Cetopsis_, and _Astrophysus_.
+
+Others have a series of bony scutes along the middle of the side; they
+form the genus _Doras_ with two closely allied forms, _Oxydoras_ and
+_Rhinodoras_. Some twenty-five species are known, all from rivers of
+tropical America, flowing into the Atlantic. These fishes have excited
+attention by their habit of travelling, during the dry season, from a
+piece of water about to dry up, in quest of a pond of greater capacity.
+These journeys are occasionally of such a length that the fish spends
+whole nights on the way, and the bands of scaly travellers are
+sometimes so large that the Indians who happen to meet them, fill many
+baskets of the prey thus placed in their hands. The Indians supposed
+that the fish carry a supply of water with them, but they have no
+special organs, and can only do so by closing the gill-openings, or by
+retaining a little water between the plates of their bodies, as Hancock
+supposes. The same naturalist adds that they make regular nests, in
+which they cover up their eggs with care and defend them, male and
+female uniting in this parental duty until the eggs are hatched. The
+nest is constructed at the beginning of the rainy season, of leaves,
+and is sometimes placed in a hole scooped out in the beach.
+
+Finally, in the last genus, the lateral scutes are likewise absent,
+viz. in
+
+   SYNODONTIS.--The adipose fin is of moderate length or rather
+   long; the dorsal fin has a very strong spine and seven soft
+   rays. The teeth in the lower jaw are movable, long, very thin
+   at the base, and with a slightly-dilated brown apex. Mouth
+   small. Barbels six, more or less fringed with a membrane or with
+   filaments. Neck with broad dermal bones.
+
+Synodontis is characteristic of the fauna of tropical Africa, where it
+is represented by fifteen species. Several occur in the Nile, and are
+known by the vernacular name “Schal.” Some attain a length of two feet.
+The species figured is from West Africa, and characterised by its long
+upper jaw.
+
+  [Illustration: Fig. 263.--Synodontis xiphias.]
+
+
+                          _b_. RHINOGLANINA.
+
+   RHINOGLANIS.--Two dorsal fins, both composed of rays, the first
+   with a strong spine; anal rather short. Barbels six; anterior
+   and posterior nostrils close together, the posterior very large,
+   open. Neck with broad dermal bones. Ventrals with seven rays,
+   inserted below the posterior rays of the first dorsal fin.
+
+   This Siluroid is known from a single example only one and a
+   half inches long, obtained at Gondokoro on the Upper Nile.
+   _Callomystax_ represents this type in the Ganges and Indus.
+
+
+                          _c_. MALAPTERURINA.
+
+   MALAPTERURUS.--One dorsal fin only, which is adipose and
+   situated before the caudal; anal of moderate length or short;
+   caudal rounded; ventrals six-rayed, inserted somewhat behind the
+   middle of the body; pectorals without pungent spine. Barbels
+   six: one to each maxillary and two on each side of the mandible.
+   The anterior and posterior nostrils are remote from each other.
+   No teeth on the palate. The entire head and body covered with
+   soft skin. Eyes small. Gill-opening very narrow, reduced to a
+   slit before the pectoral.
+
+The “Electric Cat- or Sheath-fishes” are not uncommon in the fresh
+waters of tropical Africa; three species have been described, of which
+_M. electricus_ occurs in the Nile; they grow to a length of about
+four feet. Although the first dorsal fin is absent, its position (if it
+had been developed) is indicated by a rudimentary interneural spine,
+which rests in the cleft of the neural process of the first vertebra.
+The electric organ extends over the whole body, but is thickest on the
+abdomen; it lies between two aponeurotic membranes, below the skin, and
+consists of rhomboidal cells which contain a rather firm gelatinous
+substance. The electric nerve takes its origin from the spinal chord,
+does not enter into connection with ganglia, and consists of a single
+enormously-strong primitive fibre, which distributes its branches in
+the electric organ.
+
+  [Illustration: Fig. 264.--Malapterurus electricus.]
+
+VI. SILURIDÆ PROTEROPODES.--_The rayed dorsal fin is always present and
+rather short; the ventrals are inserted below (very rarely in front
+of) the dorsal. The gill-membranes are confluent with the skin of the
+isthmus, the gill-opening being reduced to a short slit. Pectorals and
+ventrals horizontal. Vent before, or not much behind, the middle of the
+length of the body._
+
+
+                          _a_. HYPOSTOMATINA.
+
+   STYGOGENES.--Adipose fin short; dorsal and anal short; the outer
+   fin-rays somewhat thickened and rough; palate toothless; cleft
+   of the mouth of moderate width, with a maxillary barbel on each
+   side; a short broad flap on each side between the nostrils,
+   which are close together. Lower lip very broad, pendent. Eyes
+   small, covered with transparent skin. Head covered with soft
+   skin. Ventrals six-rayed.
+
+These small Siluroids, which are called “Preñadillas” by the natives,
+together with the allied _Arges_, _Brontes_, and _Astroplebus_, have
+received some notoriety through Humboldt’s accounts, who adopted
+the popular belief that they live in subterranean waters within the
+bowels of the active volcanoes of the Andes, and are ejected with
+streams of mud and water during eruptions. Humboldt himself considers
+it very singular that they are not cooked and destroyed whilst they
+are vomited forth from craters or other openings. The explanation of
+their appearance during volcanic eruptions is, that they abound in the
+numerous lakes and torrents of the Andes, that they are killed by the
+sulphuretted gases escaping during an eruption, and swept down by the
+torrents of water issuing from the volcano.
+
+   CALLICHTHYS.--Adipose fin short, supported anteriorly by a short
+   movable spine; dorsal with a feeble spine and seven or eight
+   rays; anal short. Teeth minute or entirely absent; cleft of the
+   mouth rather narrow, with a pair of maxillary barbels on each
+   side, which are united at the base. Eyes small. Head covered
+   with osseous plates; body wholly protected by two series of
+   large imbricate shields on each side. Ventrals six-rayed.
+
+Twelve species of this genus are known; they are small, and similarly
+distributed as _Doras_, with which they have much in common as regards
+their mode of life. They likewise are able to travel over land, and
+construct nests for their ova.
+
+  [Illustration: Fig. 265.--Callichthys armatus, from the Upper
+  Amazon. Natural size.]
+
+   CHÆTOSTOMUS.--A short adipose fin, supported anteriorly by a
+   short, compressed, curved spine; dorsal fin of moderate length,
+   with from eight to ten rays, the first of which is simple; anal
+   fin short; ventral six-rayed; pectoral with a strong spine. Head
+   and body completely cuirassed, the lower parts being sometimes
+   naked; body rather short, with four or five longitudinal series
+   of large imbricate scutes on each side; tail not depressed.
+   Snout produced, obtuse in front; mouth inferior, transverse,
+   with a single series of generally very fine bent teeth in both
+   jaws. Interoperculum very movable and armed with erectile spines.
+
+   This genus, with the allied _Plecostomus_, _Liposarcus_,
+   _Pterygoplichthys_, _Rhinelepis_, _Acanthicus_, and
+   _Xenomystus_, is well represented in the fresh waters of South
+   America, whence about sixty species are known. The majority
+   do not exceed a length of twelve inches, but some attain to
+   more than double that size. In some of the species the male is
+   provided with long bristles round the margin of the snout and
+   interoperculum.
+
+  [Illustration: Fig. 266.--Upper and Lower side of the head of
+  _Chætostomus heteracanthus_, Upper Amazons.]
+
+   _Hypoptopoma._--Differing from _Chætostomus_ in the peculiar
+   formation of the head, which is depressed, spatulate, the eyes
+   being on the lateral edge of the head. The movable gill-covers
+   are reduced to two bones, neither of which is armed, viz.--the
+   operculum small and placed as in _Chætostomus_, and a second,
+   larger one, separated from the eye by the narrow sub-orbital
+   ring, and placed at the lower side of the head.
+
+  [Illustration: Fig. 267.--_Hypoptopoma thoracatum_, Upper
+  Amazons. Natural size.]
+
+   LORICARIA.--One short dorsal fin; anal short; the outer ray
+   of each fin thickened, but flexible. Head depressed, with the
+   snout more or less produced and spatulate. Mouth situated at the
+   lower side of the snout, remote from its extremity, transverse,
+   surrounded by broad labial folds which are sometimes fringed;
+   a short barbel at each corner of the mouth. Teeth in the jaws
+   small, bent, with a dilated, notched apex, in a single series,
+   sometimes absent. Head and body cuirassed; tail depressed, long;
+   eye rather small or of moderate size.
+
+  [Illustration: Fig. 268.--_Loricaria lanceolate_, Upper
+  Amazons. Natural size.]
+
+Small fishes from rivers of tropical America; about twenty-six species
+are known. The male of some species has a bearded or bristly snout.
+
+   ACESTRA differs from _Loricaria_ in having the snout much
+   prolonged.
+
+   SISOR.--Head depressed, spatulate; trunk depressed; tail
+   long and thin. One short dorsal fin; anal short; ventrals
+   seven-rayed. Head partially osseous, rough; a series of bony
+   plates along the median line of the back; lateral line rough.
+   Eyes very small. Mouth inferior, small, transverse, with
+   barbels; teeth none.
+
+A single species, _S. rhabdophorus_, from rivers of northern Bengal.
+Allied to this genus is _Erethistes_ from Assam.
+
+   PSEUDECHENEIS.--Adipose fin of moderate length; a short dorsal
+   with one spine and six rays; anal fin rather short. Barbels
+   eight. Mouth small, inferior. Head depressed, covered with soft
+   skin above; eyes small, superior. Caudal fin forked; pectorals
+   horizontal, with a thoracic adhesive apparatus between, formed
+   by transverse plaits of the skin. Ventrals six-rayed.
+
+A very small species, inhabiting the mountain-streams of Khassya; by
+means of the adhesive apparatus it is enabled to hold on to stones,
+thus preventing the current from sweeping it away. _Exostoma_ is
+a similar small Siluroid from Indian mountain-streams, but without the
+thoracic apparatus; probably its mouth performs the same function.
+
+
+                           _b_. ASPREDININA.
+
+   ASPREDO.--Adipose fin none; dorsal short, without pungent spine;
+   anal very long, but not united with the caudal. Head broad,
+   much depressed; tail very long and slender. Barbels not less
+   than six, one of which is attached to each intermaxillary; none
+   at the nostrils. Eyes very small. Head covered with soft skin;
+   the anterior and posterior nostrils are remote from each other.
+   Ventrals six-rayed.
+
+Six species are known from Guyana; the largest grows to a length
+of about eighteen inches. The remarkable mode of taking care of
+their ova has been noticed above (p. 161, Fig. 72). _Bunocephalus_,
+_Bunocephalichthys_, and _Harttia_, from tropical America, are other
+genera of this sub-family which remain to be mentioned.
+
+VII. SILURIDÆ OPISTHOPTERÆ.--_The rayed dorsal fin is always present,
+short, and placed above or behind the middle of the length of the body,
+above or behind the ventrals which, however, are sometimes absent;
+anal short. Nostrils remote from each other; if a nasal barbel is
+present, it belongs to the anterior nostril. Lower lip not reverted.
+The gill-membranes are not confluent with the skin of the isthmus_:
+NEMATOGENYINA and TRICHOMYCTERINA.
+
+The genera _Heptapterus_, _Nematogenys_, _Trichomycterus_,
+_Eremophilus_, and _Pariodon_, belong to this sub-family. They are
+small South American Siluroids, the majority of which inhabit waters at
+high altitudes, up to 14,000 feet above the level of the sea. In the
+Andes they replace the Loaches of the Northern Hemisphere, which they
+resemble in appearance and habits, and even in coloration, offering a
+striking example of the fact that similar forms of animals are produced
+under similar external physical conditions.
+
+VIII. SILURIDÆ BRANCHICOLÆ.--_The rayed dorsal fin is present, short,
+and placed behind the ventrals; anal short. Vent far behind the middle
+of the length of the body. Gill-membranes confluent with the skin of
+the isthmus._
+
+_Stegophilus_ and _Vandellia_, two genera from South America,
+comprising the smallest and least developed Siluroids. Their body is
+narrow, cylindrical, and elongate; a small barbel at each maxillary;
+the operculum and interoperculum are armed with short stiff spines. The
+natives of Brazil accuse these fishes of entering and ascending the
+urethra of persons while bathing, causing inflammation and sometimes
+death. This requires confirmation, but there is no doubt that they live
+parasitically in the gill-cavity of larger fishes (_Platystoma_), but
+probably they enter these cavities only for places of safety, without
+drawing any nourishment from their host.
+
+
+                       SECOND FAMILY--SCOPELIDÆ.
+
+_Body naked or scaly. Margin of the upper jaw formed by the
+intermaxillary only; opercular apparatus sometimes incompletely
+developed. Barbels none. Gill-opening very wide; pseudobranchiæ well
+developed. Air-bladder none. Adipose fin present. The eggs are enclosed
+in the sacs of the ovary, and excluded by oviducts. Pyloric appendages
+few in number or absent. Intestinal tract very short._
+
+Exclusively marine, the majority being either pelagic or deep-sea
+forms. Of fossil remains the following have been referred to this
+family:--_Osmeroides_, from Mount Lebanon, which others believe to be
+a marine salmonoid; _Hemisaurida_, from Comen, allied to _Saurus_;
+_Parascopelus_ and _Anapterus_, from the miocene of Licata, the latter
+genus allied to _Paralepis_.
+
+   SAURUS (inclus. _Saurida_).--Body sub-cylindrical, rather
+   elongate, covered with scales of moderate size; head oblong;
+   cleft of the mouth very wide; intermaxillary very long,
+   styliform, tapering; maxillary thin, long, closely adherent
+   to the intermaxillary. Teeth card-like, some being elongate,
+   slender; all can be laid downwards and inwards. Teeth on the
+   tongue, and palatine bones. Eye of moderate size. Pectorals
+   short; ventrals eight- or nine-rayed, inserted in advance of the
+   dorsal, not far behind the pectorals. Dorsal fin nearly in the
+   middle of the length of the body, with thirteen or less rays;
+   adipose fin small; anal short or of moderate length; caudal
+   forked.
+
+Fifteen species of small size, from the shores of the tropical and
+sub-tropical zones. The species figured on p. 42, Fig. 5, occurs on the
+north-west coast of Australia and in Japan.
+
+   BATHYSAURUS.--Shape of the body similar to that of _Saurus_,
+   sub-cylindrical, elongate, covered with small scales. Head
+   depressed, with the snout produced, flat above. Cleft of the
+   mouth very wide, with the lower jaw projecting; intermaxillary
+   very long, styliform, tapering, not movable. Teeth in the jaws,
+   in broad bands, not covered by lips, curved, unequal in size
+   and barbed at the end. A series of similar teeth runs along the
+   whole length of each side of the palate. Eye of moderate size,
+   lateral. Pectoral of moderate length. Ventral eight-rayed,
+   inserted immediately behind the pectoral. Dorsal fin in the
+   middle of the length of the body, with about eighteen rays.
+   Adipose fin absent or present. Anal of moderate length. Caudal
+   emarginate.
+
+Deep-sea fishes, obtained in the Pacific at depths varying from 1100 to
+2400 fathoms. The largest example is twenty inches long. Two species.
+
+   BATHYPTEROIS.--Shape of the body like that of an _Aulopus_. Head
+   of moderate size, depressed in front, with the snout projecting,
+   the large mandible very prominent beyond the upper jaw. Cleft
+   of the mouth wide; maxillary developed, very movable, much
+   dilated behind. Teeth in narrow villiform bands in the jaws. On
+   each side of the broad vomer a small patch of similar teeth;
+   none on the palatines or on the tongue. Eye very small. Scales
+   cycloid, adherent, of moderate size. Rays of the pectoral fin
+   much elongated, some of the upper being separate from the rest,
+   and forming a distinct division. Ventrals abdominal, with the
+   outer rays prolonged, eight-rayed. Dorsal fin inserted in the
+   middle of the body, above or immediately behind the root of the
+   ventral, of moderate length. Adipose fin present or absent. Anal
+   short. Caudal forked.
+
+This very singular form is one of the discoveries of the “Challenger;”
+it is widely distributed over the seas of the Southern Hemisphere, in
+depths varying from 520 to 2600 fathoms. The elongate pectoral rays
+are most probably organs of touch. Four species were discovered, the
+largest specimen being thirteen inches long.
+
+   HARPODON.--Body elongate, covered with very thin, diaphanous,
+   deciduous scales. Head thick, with very short snout; its bones
+   are very soft, and the superficial ones are modified into wide
+   muciferous cavities; the lateral canal of the body is also
+   very wide, and a pair of pores corresponds to each scale of the
+   lateral line, one being above, the other below the scale. Cleft
+   of the mouth very wide; intermaxillary very long, styliform,
+   tapering; maxillary absent. Teeth card-like, recurved, unequal
+   in size; the largest are in the lower jaw, and provided with a
+   single barb at the posterior margin of the point. Eye small.
+   Ventral fins long, nine-rayed, inserted below the anterior
+   dorsal rays; dorsal fin in the middle of the length of the
+   body; adipose fin small; anal of moderate length; caudal fin
+   three-lobed, the lateral line being continued along the central
+   lobe. Centre of the vertebræ open in the middle.
+
+Two species only are known of this singular genus; both are evidently
+inhabitants of considerable depths, and periodically come nearer to
+the surface. One (_H. nehereus_) is well known in the East Indies,
+being of excellent flavour. When newly taken its body is brilliantly
+phosphorescent. When salted and dry it is known under the names of
+“Bombay-ducks” or “Bummaloh,” and exported in large quantities from
+Bombay and the coast of Malabar. The second species (_H. microchir_)
+exceeds the other in length, and has been found in the sea off Japan.
+
+  [Illustration: Fig. 269.--Scopelus boops.]
+
+   SCOPELUS.--Body oblong, more or less compressed, covered with
+   large scales. Series of phosphorescent spots run along the lower
+   side of the body, and a similar glandular substance sometimes
+   occupies the front of the snout and the back of the tail. Cleft
+   of the mouth very wide. Intermaxillary very long, styliform,
+   tapering; maxillary well developed. Teeth villiform. Eye large.
+   Ventrals eight-rayed, inserted immediately in front of or below
+   the anterior dorsal rays. Dorsal fin nearly in the middle of
+   the length of the body; adipose fin small; anal generally long;
+   caudal forked. Branchiostegals from eight to ten.
+
+The fishes of this genus are small, of truly pelagic habits, and
+distributed over all the temperate and tropical seas; they are so
+numerous that the surface-net, when used during a night of moderate
+weather, scarcely ever fails to enclose some specimens. They come to
+the surface at night only; during the day and in very rough weather
+they descend to depths where they are safe from sunlight or the
+agitation of the water. Some species never rise to the surface; indeed,
+Scopeli have been brought up in the dredge from almost any depth to
+2500 fathoms. Thirty species are known. _Gymnoscopelus_ differs from
+_Scopelus_ in lacking scales.
+
+   IPNOPS.--Body elongate, sub-cylindrical, covered with large,
+   thin, deciduous scales, and without phosphorescent organs. Head
+   depressed, with broad, long, spatulate snout, the whole upper
+   surface of which is occupied by a most peculiar organ of vision
+   (or luminosity), longitudinally divided in two symmetrical
+   halves. Bones of the head well ossified. Mouth wide, with the
+   lower jaw projecting; maxillary dilated behind. Both jaws with
+   narrow bands of villiform teeth; palate toothless. Pectoral and
+   ventral fins well developed, and, owing to the shortness of the
+   trunk, close together. Dorsal fin at a short distance behind
+   the vent; adipose fin none; anal fin moderately long; caudal
+   subtruncated. Pseudobranchiæ none.
+
+This singular genus, one of the “Challenger” discoveries, is known
+from four examples, obtained at depths varying between 1600 and 2150
+fathoms, off the coast of Brazil, near Tristan d’Acunha and north of
+Celebes. All belong to one species, _I. murrayi_. The eye seems to
+have lost its function of vision and assumed that of producing light.
+The specimens are from 4 to 5½ inches long.
+
+   PARALEPIS.--Head and body elongate, compressed, covered with
+   deciduous scales. Cleft of the mouth very wide; maxillary
+   developed, closely adherent to the intermaxillary. Teeth in
+   a single series, unequal in size. Eye large. Ventrals small,
+   inserted opposite or nearly opposite the dorsal. Dorsal fin
+   short, on the hinder part of the body; adipose fin small; anal
+   elongate, occupying the end of the tail; caudal emarginate.
+
+Three species; small pelagic fishes from the Mediterranean and
+Atlantic.--_Sudis_, from the Mediterranean, has a dentition
+slightly different from that of _Paralepis_.
+
+   Plagyodus.--Body elongate, compressed, scaleless; snout much
+   produced, with very wide cleft of the mouth. Intermaxillary very
+   long and slender; maxillary thin, immovable. Teeth in the jaws
+   and of the palate very unequal in size, the majority pointed
+   and sharp, some very large and lanceolate. Eye large. Pectoral
+   and ventral fins well developed; the rayed dorsal fin occupies
+   the whole length of the back from the occiput to opposite the
+   anal fin; adipose and anal fins of moderate size. Caudal forked.
+   Branchiostegals six or seven.
+
+  [Illustration: Fig. 270.--Plagyodus ferox.]
+
+This is one of the largest and most formidable deep-sea fishes. One
+species only is well known, _P. ferox_, from Madeira and the sea
+off Tasmania; other species have been noticed from Cuba and the
+North Pacific, but it is not evident in what respects they differ
+specifically from _P. ferox_. This fish grows to a length of six feet,
+and from the stomach of one example have been taken several Octopods,
+Crustaceans, Ascidians, a young Brama, twelve young Boar-fishes,
+a Horse-mackerel, and one young of its own species. The stomach is
+coecal; the commencement of the intestine has extremely thick walls,
+its inner surface being cellular, like the lung of a reptile; a
+pyloric appendage is absent. All the bones are extremely thin, light,
+and flexible, containing very little earthy matter; singular is the
+development of a system of abdominal ribs, symmetrically arranged on
+both sides, and extending the whole length of the abdomen. Perfect
+specimens are rarely obtained on account of the want of coherence of
+the muscular and osseous parts, caused by the diminution of pressure
+when the fish reaches the surface of the water. The exact depth at
+which _Plagyodus_ lives is not known; probably it never rises above a
+depth of 300 fathoms.
+
+The other less important genera belonging to this family are _Aulopus_,
+_Chlorophthalmus_, _Scopelosaurus_, _Odontostomus_, and _Nannobrachium_.
+
+  [Illustration: Fig. 271.--Pharyngeal bones and teeth of the
+  Bream, Abramis brama.]
+
+
+                       THIRD FAMILY--CYPRINIDÆ.
+
+_Body generally covered with scales; head naked. Margin of the upper
+jaw formed by the intermaxillaries. Belly rounded, or, if trenchant,
+without ossifications. No adipose fin. Stomach without blind sac.
+Pyloric appendages none. Mouth toothless; lower pharyngeal bones
+well developed, falciform, sub-parallel to the branchial arches,
+provided with teeth, which are arranged in one, two, or three series.
+Air-bladder large, divided into an anterior and posterior portion by a
+constriction, or into a right or left portion, enclosed in an osseous
+capsule. Ovarian sacs closed._
+
+The family of “Carps” is the one most numerously represented in the
+fresh waters of the Old World and of North America. Also numerous
+fossil remains are found in tertiary freshwater-formations, as in the
+limestones of Oeningen and Steinheim, in the lignites of Bonn, Stöchen,
+Bilin, and Ménat, in the marl slates and carbonaceous shales of
+Licata in Sicily, and of Padang in Sumatra, in corresponding deposits
+of Idaho in North America. The majority can be referred to existing
+genera: _Barbus_, _Thynnichthys_, _Gobio_, _Leuciscus_, _Tinca_,
+_Amblypharyngodon_, _Rhodeus_, _Cobitis_, _Acanthopsis_, only a few
+showing characters different from those of living genera: _Cyclurus_,
+_Hexapsephus_, _Mylocyprinus_ (tertiary of North America).
+
+Most Carps feed on vegetable and animal substances; a few only are
+exclusive vegetable feeders. There is much less diversity of form and
+habits in this family than in the Siluroids; however, the genera are
+sufficiently numerous to demand a further subdivision of the family
+into groups.
+
+I. CATOSTOMINA.--_Pharyngeal teeth in a single series, exceedingly
+numerous and closely set. Dorsal fin elongate, opposite to the
+ventrals; anal short, or of moderate length. Barbels none._
+
+These fishes are abundant in the lakes and rivers of North America,
+more than thirty species having been described, and many more named,
+by American ichthyologists. Two species are known from North-Eastern
+Asia. They are generally called “Suckers,” but their vernacular
+nomenclature is very arbitrary and confused. Some of the species
+which inhabit the large rivers and lakes grow to a length of three
+feet and a weight of fifteen pounds. The following genera may be
+distinguished:--_Catostomus_, “Suckers,” “Red-horses,” “Stone-rollers,”
+“White Mullets;” _Moxostoma_; _Sclerognathus_, “Buffaloes,” “Black
+Horses;” and _Carpiodes_, “Spear-fish,” “Sail-fish.”
+
+II. CYPRININA.--_Anal fin very short, with not more than five or six,
+exceptionally seven, branched rays. Dorsal fin opposite ventrals.
+Abdomen not compressed. Lateral line running along the median line
+of the tail. Mouth frequently with barbels, never more than four in
+number. Pharyngeal teeth generally in a triple series in the Old World
+genera; in a double or single series in the North American forms, which
+are small and feebly developed. Air-bladder present, without osseous
+covering._
+
+   CYPRINUS.--Scales large. Dorsal fin long, with a more or less
+   strong serrated osseous ray; anal short. Snout rounded, obtuse,
+   mouth anterior, rather narrow. Pharyngeal teeth, 3. 1. 1.-1. 1.
+   3, molar-like. Barbels four.
+
+  [Illustration: Fig. 272.--The Carp, Cyprinus carpio.]
+
+The “Carp” (_C. carpio_, “Karpfen,” “La carpe,”) is originally a
+native of the East, and abounds in a wild state in China, where it
+has been domesticated for many centuries; thence it was transported
+to Germany and Sweden, and the year 1614 is assigned as the date of
+its first introduction into England. It delights in tranquil waters,
+preferring such as have a muddy bottom, and the surface partially
+shaded with plants. Its food consists of the larvæ of aquatic insects,
+minute testacea, worms, and the tender blades and shoots of plants. The
+leaves of lettuce, and other succulent plants of a similar kind, are
+said to be particularly agreeable to them, and to fatten them sooner
+than any other food. Although the Carp eats with great voracity when
+its supply of aliment is abundant, it can subsist for an astonishing
+length of time without nourishment. In the winter, when the Carps
+assemble in great numbers, and bury themselves among the mud and the
+roots of plants, they often remain for many months without eating. They
+can also be preserved alive for a considerable length of time out of
+the water, especially if care be taken to moisten them occasionally
+as they become dry. Advantage is often taken of this circumstance to
+transport them alive, by packing them among damp herbage or damp linen;
+and the operation is said to be unattended with any risk to the animal,
+especially if the precaution be taken to put a piece of bread in its
+mouth steeped in brandy!
+
+The fecundity of these fishes is very great, and their numbers
+consequently would soon become excessive but for the many enemies by
+which their spawn is destroyed. No fewer than 700,000 eggs have been
+found in the ovaries of a single Carp, and that, too, by no means an
+individual of the largest size. Their growth is very rapid, more so
+perhaps than that of any other Freshwater fish, and the size which they
+sometimes attain is very considerable. In certain lakes in Germany
+individuals are occasionally taken weighing thirty or forty pounds; and
+Pallas relates that they occur in the Volga five feet in length, and
+even of greater weight than the examples just alluded to. The largest
+of which we have any account is that mentioned by Bloch, taken near
+Frankfort-on-the-Oder, which weighed seventy pounds, and measured
+nearly nine feet in length,--a statement the accuracy of which is very
+much open to doubt.
+
+Like other domesticated animals the Carp is subject to variation; some
+individuals, especially when they have been bred under unfavourable
+circumstances, have a lean and low body; others are shorter and higher.
+Some have lost every trace of scales, and are called “Leather-carps;”
+others retain them along the lateral line and on the back only
+(“Spiegelkarpfen” of the Germans). Finally, in some are the fins much
+prolonged, as in certain varieties of the Gold-fish. Cross-breeds
+between the Carp and the Crucian Carp are of common occurrence.
+The Carp is much more esteemed as food in inland countries than in
+countries where the more delicate kinds of sea fishes can be obtained.
+
+   CARASSIUS differs from _Cyprinus_ in lacking barbels; its
+   pharyngeal teeth are compressed, in a single series, 4–4.
+
+Two well-known species belong to this genus. The “Crucian Carp” (_C.
+carassius_, “Karausche”) is generally distributed over Central and
+Northern Europe, and extends into Italy and Siberia. It inhabits
+stagnant waters only, and is so tenacious of life that it will
+survive a lengthened sojourn in the smallest pools, where, however,
+it remains stunted; whilst in favourable localities it attains to a
+length of twelve inches. It is much subject to variation of form; very
+lean examples are commonly called “Prussian Carps.” Its usefulness
+consists in keeping ponds clean from a super-abundance of vegetable
+growth, and in serving as food for other more esteemed fishes. The
+second species is the “Gold-fish,” _Carassius auratus_. It is of very
+common occurrence in a wild state in China and the warmer parts of
+Japan, being entirely similar in colour to the Crucian Carp. In a
+domesticated state it loses the black or brown chromatophors, and
+becomes of a golden-yellow colour; perfect Albinos are comparatively
+scarcer. Many varieties and monstrosities have been produced during
+the long period of its domestication; the variety most highly priced
+at present being the so-called “Telescope-fish,” of which a figure is
+annexed. The Gold-fish is said to have been first brought to England
+in the year 1691, and is now distributed over nearly all the civilised
+parts of the world.
+
+  [Illustration: Fig. 273.--Cyprinus auratus, var.]
+
+   CATLA.--Scales of moderate size. Dorsal fin without osseous ray,
+   with more than nine branched rays, commencing nearly opposite to
+   the ventrals. Snout broad, with the integuments very thin; there
+   is no upper lip, the lower with a free continuous posterior
+   margin. Symphysis of the mandibulary bones loose, with prominent
+   tubercles. Mouth anterior. Barbels none. Gill-rakers very long,
+   fine, and closely set. Pharyngeal teeth, 5. 3. 2.-2. 3. 5.
+
+The “Catla” (_C. buchanani_), one of the largest Carps of the Ganges,
+growing to a length of more than three feet, and esteemed as food.
+
+   LABEO.--Scales of moderate or small size. Dorsal fin without
+   osseous ray, with more than nine branched rays, commencing
+   somewhat in advance of the ventrals. Snout obtusely rounded,
+   the skin of the maxillary region being more or less thickened,
+   forming a projection beyond the mouth. Mouth transverse,
+   inferior, with the lips thickened, each or one of them being
+   provided with an inner transverse fold, which is covered with a
+   deciduous horny substance forming a sharp edge, which, however,
+   does not rest upon the bone as base, but is soft and movable.
+   Barbels very small, two or four; the maxillary barbels more or
+   less hidden in a groove behind the angle of the mouth. Anal
+   scales not enlarged. Pharyngeal teeth uncinate, 5. 4. 2.-2. 4.
+   5. Snout generally more or less covered with hollow tubercles.
+
+About thirteen species are known from rivers of tropical Africa and the
+East Indies.
+
+   DISCOGNATHUS.--Scales of moderate size. Dorsal fin without
+   osseous ray, with not more than nine branched rays, commencing
+   somewhat in advance of the ventrals. Snout obtusely rounded,
+   more or less depressed, projecting beyond the mouth, more or
+   less tubercular. Mouth inferior, transverse, crescent-shaped;
+   lips broad, continuous, with an inner sharp edge of the jaws,
+   covered with horny substance on the lower jaw; upper lip more
+   or less distinctly fringed; lower lip modified into a suctorial
+   disk, with free anterior and posterior margins. Barbels two or
+   four; if two, the upper are absent. Anal scales not enlarged.
+   Pectoral fins horizontal. Pharyngeal teeth, 5. 4. 2.-2. 4. 5.
+
+A small fish (_D. lamta_), extremely abundant in almost all the
+mountain streams from Abyssinia and Syria to Assam.
+
+   CAPOËTA.--Scales small, of moderate or large size. Dorsal fin
+   with or without a strong osseous ray, with not more than nine
+   branched rays. Snout rounded, with the mouth transverse and at
+   its lower side; each mandible angularly bent inwards in front,
+   the anterior mandibular edge being nearly straight, sharpish,
+   and covered with a horny brown layer. No lower labial fold.
+   Barbels two (rarely four), or entirely absent. Anal scales not
+   conspicuously enlarged. Pharyngeal teeth compressed, truncated,
+   5 or 4. 3. 2–2. 3. 4 or 5.
+
+Characteristic of the fauna of Western Asia; one species from
+Abyssinia. Of the fifteen species known _C. damascina_ deserves to
+be specially mentioned, being abundant in the Jordan and other rivers
+of Syria and Asia Minor.
+
+   BARBUS.--Scales of small, moderate, or large size. Dorsal
+   fin generally with the (third) longest simple ray ossified,
+   enlarged, and frequently serrated; never, or only exceptionally,
+   with more than nine branched rays, commencing opposite or nearly
+   opposite to the root of the ventral fin. Eyes without adipose
+   eyelid. Anal fin frequently very high. Mouth arched, without
+   inner folds, inferior or anterior; lips without horny covering.
+   Barbels short, four, two, or none. Anal scales not enlarged.
+   Pharyngeal teeth 5. 4 or 3. 3 or 2.-2 or 3. 3 or 4. 5. Snout but
+   rarely with tubercles or pore-like grooves.
+
+No other genus of Cyprinoids is composed of so many species as the
+genus of “Barbels,” about 200 being known from the tropical and
+temperate parts of the Old World; it is not represented in the New
+World. Although the species differ much from each other in the form of
+the body, number of barbels, size of the scales, strength of the first
+dorsal ray or spine, etc., the transition between the extreme forms is
+so perfect that no further generic subdivision should be attempted.
+Some attain a length of six feet, whilst others never exceed a length
+of two inches. The most noteworthy are the large Barbels of the Tigris
+(_B. subquincunciatus_, _B. esocinus_, _B. scheich_, _B. sharpeyi_);
+the common Barbel of Central Europe and Great Britain (_B. vulgaris_);
+the “Bynni” of the Nile (_B. bynni_); _B. canis_ from the Jordan; the
+“Mahaseer” of the mountain streams of India (_B. mosal_), probably the
+largest of all species, the scales of which are sometimes as large as
+the palm of a hand. The small, large-scaled species are especially
+numerous in the East Indies and the fresh waters of Tropical Africa.
+
+   THYNNICHTHYS.--Scales small. Dorsal fin without an osseous
+   ray, with not more than nine branched rays, commencing nearly
+   opposite the ventrals. Head large, strongly compressed; eye
+   without well-developed adipose membrane, in the middle of
+   the depth of the head. Snout with the integuments very thin;
+   there is no upper lip, and the lower jaw has a thin labial
+   fold on the sides only. Mouth anterior and lateral; barbels
+   none. Gill-rakers none; laminæ branchiales long, half as long
+   as the post-orbital portion of the head; pseudobranchiæ none.
+   Pharyngeal teeth lamelliform, with flat oblong crown, 5. 3 or 4.
+   2–2. 4 or 3. 5, the teeth of the three series being wedged into
+   one another.
+
+Three species from the East Indies.
+
+   OREINUS.--Scales very small. Dorsal fin with a strong osseous
+   serrated ray, opposite to the ventrals. Snout rounded, with the
+   mouth transverse, and at its lower side; mandibles broad, short,
+   and flat, loosely joined together; margin of the jaw covered
+   with a thick horny layer; a broad fringe-like lower lip, with
+   free posterior margin. Barbels four. Vent and anal fin in a
+   sheath, covered with enlarged tiled scales. Pharyngeal teeth
+   pointed, more or less hooked, 5. 3. 2–2. 3. 5.
+
+Three species from mountain streams of the Himalayas.
+
+   SCHIZOTHORAX.--Hill-barbels, with the same singular sheath on
+   each side of the vent, as in the preceding genus; but they
+   differ in having the mouth normally formed, with mandibles of
+   the usual length and width.
+
+Seventeen species are known from fresh waters of the Himalayas, and
+north of them. Other genera from the same region, and with the anal
+sheath, are _Ptychobarbus_, _Gymnocypris_, _Schizopygopsis_, and
+_Diptychus_.
+
+   GOBIO.--Scales of moderate size; lateral line present. Dorsal
+   fin short, without spine. Mouth inferior; mandible not
+   projecting beyond the upper jaw when the mouth is open; both
+   jaws with simple lips; a small but very distinct barbel at the
+   angle of the mouth, quite at the extremity of the maxillary.
+   Gill-rakers very short; pseudobranchiæ. Pharyngeal teeth, 5. 3
+   or 2.--2 or 3. 5, hooked at the end.
+
+The “Gudgeons” are small fishes of clear fresh waters of Europe;
+they are, like the barbels, animal feeders. In Eastern Asia they
+are represented by two closely allied genera, _Ladislavia_ and
+_Pseudogobio_.
+
+   CERATICHTHYS.--Scales of moderate or small size; lateral line
+   present. Dorsal fin short, without spine, not or but slightly
+   in advance of the ventrals. Mouth subinferior; the lower jaw
+   does not project beyond the upper when the mouth is open;
+   intermaxillaries protractile from below the maxillaries; both
+   jaws with thickish lips; a small barbel at the angle of the
+   mouth, quite at the extremity of the maxillary. Gill-rakers very
+   short and few in number: pseudobranchiæ. Pharyngeal teeth 4–4.
+   hooked at the end (sometimes 4, 1--1. 4).
+
+About ten species are known from North America; they are small, and
+called “Chub” in the United States. _C. biguttatus_ is, perhaps,
+the most widely-diffused Freshwater-fish in the United States, and
+common everywhere. Breeding males have generally a red spot on each
+side of the head.
+
+Other similar genera from the fresh waters of North America, and
+generally called “Minnows,” are _Pimephales_ (the “Black Head”),
+_Hyborhynchus_, _Hybognathus_, _Campostoma_ (the “Stone-lugger”),
+_Ericymba_, _Cochlognathus_, _Exoglossum_ (the “Stone Toter” or
+“Cut-lips”), and _Rhinichthys_ (the “Long-nosed Dace”).
+
+The remaining Old World genera belonging to the group _Cyprinina_ are
+_Cirrhina_, _Dangila_, _Osteochilus_, _Barynotus_, _Tylognathus_,
+_Abrostomus_, _Crossochilus_, _Epalzeorhynchus_, _Barbichthys_,
+_Amblyrhynchichthys_, _Albulichthys_, _Aulopyge_, _Bungia_, and
+_Pseudorasbora_.
+
+III. ROHTEICHTHYINA.--_Anal fin very short, with not more than six
+branched rays. Dorsal fin behind ventrals. Abdomen compressed. Lateral
+line running along the median line of the tail. Mouth without barbels.
+Pharyngeal teeth in a triple series._
+
+One genus and species only, _Rohteichthys microlepis_, from Borneo and
+Sumatra.
+
+IV. LEPTOBARBINA.--_Anal fin very short, with not more than six
+branched rays. Dorsal fin opposite to ventrals. Abdomen not compressed.
+Lateral line running in the lower half of the tail. Barbels present,
+not more than four in number. Pharyngeal teeth in a triple series._
+
+One genus and species only, _Leptobarbus hoevenii_, from Borneo and
+Sumatra.
+
+V. RASBORINA.--_Anal fin very short, with not more than six branched
+rays. Dorsal fin inserted behind the origin of the ventrals. Abdomen
+not compressed. Lateral line running along the lower half of the
+tail, if complete. Mouth sometimes with barbels, which are nevermore
+than four in number. Pharyngeal teeth in a triple, or single series.
+Air-bladder present, without osseous covering._
+
+   RASBORA.--Scales large, or of moderate size, there being
+   generally four and a half longitudinal series of scales between
+   the origin of the dorsal fin and the lateral line, and one
+   between the lateral line and the ventral. Lateral line curved
+   downwards. Dorsal fin with seven or eight branched rays, not
+   extending to above the anal, which is seven-rayed. Mouth of
+   moderate width, extending to the front margin of the orbit,
+   with the lower jaw slightly prominent, and provided with three
+   prominences in front, fitting into grooves of the upper jaw;
+   barbels none, in one species two. Gill-rakers short, lanceolate.
+   Pseudobranchiæ. Pharyngeal teeth in three series, uncinate.
+
+Thirteen species of small size from the East Indian Continent and
+Archipelago, and from rivers on the east coast of Africa.
+
+   AMBLYPHARYNGODON.--Scales small; lateral line incomplete. Dorsal
+   fin without an osseous ray, with not more than nine branched
+   rays, commencing a little behind the origin of the ventrals.
+   Head of moderate size, strongly compressed; eye without adipose
+   membrane; snout with the integuments very thin; there is no
+   upper lip, and the lower jaw has a short labial fold on the
+   sides only. Mouth anterior, somewhat directed upwards, with
+   the lower jaw prominent. Barbels none. Gill-rakers extremely
+   short; pseudobranchiæ. Pharyngeal teeth molar-like, with their
+   crowns concave, 3. 2. 1.--1. 2. 3. Intestinal tract narrow, with
+   numerous convolutions.
+
+Three species of small size from the Continent of India.
+
+To the same group belong _Luciosoma_, _Nuria_, and _Aphyocypris_, from
+the same geographical region.
+
+VI. SEMIPLOTINA.--_Anal fin short, with seven branched rays, not
+extending forwards to below the dorsal. Dorsal fin elongate, with an
+osseous ray. Lateral line running along the middle of the tail. Mouth
+sometimes with barbels._
+
+Two genera: _Cyprinion_, from Syria and Persia, and _Semiplotus_ from
+Assam.
+
+VII. XENOCYPRIDINA.--_Anal fin rather short, with seven or more
+branched rays, not extending forwards to below the dorsal fin. Dorsal
+short, with an osseous ray. Lateral line running along the middle of
+the tail. Mouth sometimes with barbels. Pharyngeal teeth in a triple or
+double series._
+
+Three genera: _Xenocypris_ and _Paracanthobrama_ from China; and
+_Mystacoleucus_ from Sumatra.
+
+VIII. LEUCISCINA.--_Anal fin short or of moderate length, with from
+eight to eleven branched rays, not extending forwards to below the
+dorsal. Dorsal fin short, without osseous ray. Lateral line, if
+complete, running along, or nearly in, the middle of the tail. Mouth
+generally without barbels. Pharyngeal teeth in a single or double
+series._
+
+   LEUCISCUS.--Body covered with imbricate scales. Dorsal fin
+   commencing opposite, rarely behind, the ventrals. Anal fin
+   generally with from nine to eleven, rarely with eight (in small
+   species only), and still more rarely with fourteen rays. Mouth
+   without structural peculiarities; lower jaw not trenchant;
+   barbels none. Pseudobranchiæ. Pharyngeal teeth conical or
+   compressed, in a single or double series. Intestinal tract
+   short, with only a few convolutions.
+
+The numerous species of this genus are comprised under the name of
+“White-fish;” they are equally abundant in the northern temperate
+zone of both hemispheres, about forty species being known from the
+Old World, and about fifty from the New. The most noteworthy species
+of the former Fauna are the “Roach” (_L. rutilus_, see Fig. 21,
+p. 50), common all over Europe north of the Alps; the “Chub” (_L.
+cephalus_), extending into Northern Italy and Asia Minor; the “Dace”
+(_L. leuciscus_), a companion of the Roach; the “Id” or “Nerfling” (_L.
+idus_), from the central and northern parts of Continental Europe,
+domesticated in some localities of Germany, in this condition assuming
+the golden hue of semi-albinism, like a Gold-fish, and then called the
+“Orfe;” the “Rudd,” or “Red-eye” (_L. erythrophthalmus_), distributed
+all over Europe and Asia Minor, and distinguished by its scarlet lower
+fins; the “Minnow” (_L. phoxinus_), abundant everywhere in Europe, and
+growing to a length of seven inches in favourable localities. The North
+American species are much less perfectly known; the smaller ones are
+termed “Minnows,” the larger “Shiner” or “Dace.” The most common are
+_L. cornutus_ (Red-fin, Red Dace); _L. neogæus_, a minnow resembling
+the European species, but with incomplete lateral line; _L. hudsonius_,
+the “Spawn-eater” or “Smelt.”
+
+   TINCA.--Scales small, deeply embedded in the thick skin; lateral
+   line complete. Dorsal fin short, its origin being opposite the
+   ventral fin; anal short; caudal subtruncated. Mouth anterior;
+   jaws with the lips moderately developed; a barbel at the angle
+   of the mouth. Gill-rakers short, lanceolate; pseudobranchiæ
+   rudimentary. Pharyngeal teeth 4 or 5.-5, cuneiform, slightly
+   hooked at the end.
+
+  [Illustration: Fig. 274.--The Tench (Tinca tinca).]
+
+Only one species of “Tench” is known (_T. tinca_), found all over
+Europe in stagnant waters with soft bottom. The “Golden Tench” is only
+a variety of colour, an incipient albinism like the Gold-fish and Id.
+Like most other Carps of this group it passes the winter in a state of
+torpidity, during which it ceases to feed. It is extremely prolific,
+297,000 ova having been counted in one female; its spawn is of a
+greenish colour.
+
+   LEUCOSOMUS.--Scales of moderate or small size; lateral line
+   present. Dorsal fin commencing opposite, or nearly opposite, to
+   the ventral. Anal fin short. Mouth anterior or sub-anterior;
+   intermaxillaries protractile. A very small barbel at the
+   extremity of the maxillary. Lower jaw with rounded margin, and
+   with the labial folds well developed laterally. Gill-rakers
+   short; pseudobranchiæ. Pharyngeal teeth in a double series.
+
+A North American genus, to which belong some of the most common species
+of the United States. _L. pulchellus_ (the “Fall-fish,” “Dace,” or
+“Roach”), one of the largest White-fishes of the Eastern States,
+attaining to a length of 18 inches, and abundant in the rapids of the
+larger rivers. _L. corporalis_ (the “Chub”), common everywhere from New
+England to the Missouri region.
+
+   CHONDROSTOMA.--Scales of moderate size or small. Lateral line
+   terminating in the median line of the depth of the tail. Dorsal
+   fin with not more than nine branched rays, inserted above the
+   root of the ventrals. Anal fin rather elongate, with ten or more
+   rays. Mouth inferior, transverse, lower jaw with a cutting edge,
+   covered with a brown horny layer. Barbels none. Gill-rakers
+   short, fine; pseudobranchiæ. Pharyngeal teeth 5 or 6 or 7.-7 or
+   6 or 5, knife-shaped, not denticulated. Peritoneum black.
+
+Seven species from the Continent of Europe and Western Asia.
+
+Other Old World genera belonging to the _Leuciscina_ are _Myloleucus_,
+_Ctenopharyngodon_, and _Paraphoxinus_; from North America:
+_Mylopharodon_, _Meda_, _Orthodon_, and _Acrochilus_.
+
+IX. RHODEINA.--_Anal fin of moderate length, with from nine to twelve
+branched rays, extending forwards to below the dorsal. Dorsal fin
+short, or of moderate length. Lateral line, if complete, running along
+or nearly in the middle of the tail. Mouth with very small, or without
+any barbels. Pharyngeal teeth in a single series._
+
+Very small roach-like fishes inhabiting chiefly Eastern Asia and Japan,
+one species (_Rh. amarus_) advancing into Central Europe. The thirteen
+species known have been distributed among four genera, _Achilognathus_,
+_Acanthorhodeus_, _Rhodeus_, and _Pseudoperilampus_. In the females a
+long external urogenital tube is developed annually during the spawning
+season. The European species is known in Germany by the name of
+“Bitterling.”
+
+X. DANIONINA.--_Anal fin of moderate length or elongate, with not less,
+and generally more, than eight branched rays. Lateral line running
+along the lower half of the tail. Mouth with small, or without any,
+barbels. Abdomen not trenchant. Pharyngeal teeth in a triple or double
+series._
+
+Small fishes from the East Indian Continent, Ceylon, the East Asiatic
+Islands, and a few from East African Rivers, The genera belonging to
+this group are _Danio_, _Pteropsarion_, _Aspidoparia_, _Barilius_,
+_Bola_, _Scharca_, _Opsariichthys_, _Squaliobarbus_, and _Ochetobus_:
+altogether about forty species.
+
+XI. HYPOPHTHALMICHTHYINA.--_Anal fin elongate. Lateral line running
+nearly along the median line of the tail. Mouth without barbels.
+Abdomen not trenchant. No dorsal spine. Pharyngeal teeth in a single
+series._
+
+One genus (_Hypophthalmichthys_) with two species from China.
+
+XII. ABRAMIDINA.--_Anal fin elongate. Abdomen, or part of the abdomen,
+compressed._
+
+  [Illustration: Fig. 275.--The Bream (Abramis brama).]
+
+   ABRAMIS.--Body much compressed, elevated, or oblong. Scales
+   of moderate size. Lateral line present, running in the lower
+   half of the tail. Dorsal fin short, with spine, opposite to the
+   space between ventrals and anals. Lower jaw generally shorter,
+   and rarely longer than the upper. Both jaws with simple lips,
+   the lower labial fold being interrupted at the symphysis of
+   the mandible. Upper jaw protractile. Gill-rakers rather short;
+   pseudobranchiæ. The attachment of the branchial membrane to the
+   isthmus takes place at some distance behind the vertical from
+   the orbit. Pharyngeal teeth in one or two series, with a notch
+   near the extremity. Belly behind the ventrals compressed into an
+   edge, the scales not extending across it.
+
+The “Breams” are represented in the temperate parts of both northern
+hemispheres; in Europe there occur the “Common Bream,” _A. brama_;
+the “Zope,” _A. ballerus_; _A. sapa_; the “Zärthe,” _A. vimba_; _A.
+elongatus_; the “White Bream,” _A. blicca_; _A. bipunctatus_. Of these
+_A. brama_ and _A. blicca_ are British; the former being one of the
+most common fishes, and sometimes attaining to a length of two feet.
+Crosses between these two species, and even with other Cyprinoids, are
+not rare. Of the American species _A. americanus_ (“Shiner,” “Bream”)
+is common and widely distributed; like the European Bream it lives
+chiefly in stagnant waters or streams with a slow current.
+
+   ASPIUS.--Body oblong; scales of moderate size; lateral line
+   complete, terminating nearly in the middle of the depth of the
+   tail. Dorsal fin short, without spine, opposite to the space
+   between the ventrals and anal; anal fin elongate, with thirteen
+   or more rays. Lower jaw more or less conspicuously projecting
+   beyond the upper. Lips thin, simple, the lower labial fold being
+   at the symphysis; upper jaw but little protractile. Gill-rakers
+   short and widely set; pseudobranchiæ. The attachment of the
+   branchial membrane to the isthmus takes place below the hind
+   margin of the orbit. Pharyngeal teeth hooked, 5. 3.-3 or 2. 5 or
+   4. Belly behind the ventrals compressed, the scales covering the
+   edge.
+
+Four species from Eastern Europe to China.
+
+   ALBURNUS.--Body more or less elongate; scales of moderate size;
+   lateral line present, running below the median line of the
+   tail. Dorsal fin short, without spine, opposite to the space
+   between ventrals and anal; anal fin elongate, with more than
+   thirteen rays. Lower jaw more or less conspicuously projecting
+   beyond the upper. Lips thin, simple, the lower labial fold
+   being interrupted at the symphysis of the mandible. Upper jaw
+   protractile. Gill-rakers slender, lanceolate, closely set;
+   pseudobranchiæ. The attachment of the branchial membrane to
+   the isthmus takes place below the hind margin of the orbit.
+   Pharyngeal teeth in two series, hooked. Belly behind the
+   ventrals compressed into an edge, the scales not extending
+   across it.
+
+“Bleak” are numerous in Europe and Western Asia, fifteen species
+being known. The common Bleak (_A. alburnus_) is found north of the
+Alps only, and represented by another species (_A. alburnellus_,
+“Alborella,” or “Avola”) in Italy.
+
+Of the other genera referred to this group, _Leucaspius_ and _Pelecus_
+belong to the European Fauna; _Pelotrophus_ is East African; all
+the others occur in the East Indies or the temperate parts of
+Asia, viz. _Rasborichthys_, _Elopichthys_, _Acanthobrama_ (Western
+Asia), _Osteobrama_, _Chanodichthys_, _Hemiculter_, _Smiliogaster_,
+_Toxabramis_, _Culter_, _Eustira_, _Chela_, _Pseudolabuca_, and
+_Cachius_.
+
+XIII. HOMALOPTERINA.--_Dorsal and anal fins short, the former opposite
+to ventrals. Pectoral and ventral fins horizontal, the former with the
+outer rays simple. Barbels six or none. Air-bladder absent. Pharyngeal
+teeth in a single series, from ten to sixteen in number._
+
+Inhabitants of hill-streams in the East Indies; they are of small size
+and abundant where they occur. Thirteen species are known belonging
+to the genera _Homaloptera_, _Gastromyzon_, _Crossostoma_, and
+_Psilorhynchus_.
+
+XIV. COBITIDINA.--_Mouth surrounded by six or more barbels. Dorsal fin
+short or of moderate length; anal fin short. Scales small, rudimentary,
+or entirely absent. Pharyngeal teeth in a single series, in moderate
+number. Air-bladder partly or entirely enclosed in a bony capsule.
+Pseudobranchiæ none_: Loaches.
+
+   MISGURNUS.--Body elongate, compressed. No sub-orbital spine. Ten
+   or twelve barbels, four belonging to the mandible. Dorsal fin
+   opposite to the ventrals; caudal rounded.
+
+Four species from Europe and Asia. _M. fossilis_ is the largest
+of European Loaches, growing to a length of ten inches; it occurs in
+stagnant waters of eastern and southern Germany and northern Asia.
+In China and Japan it is replaced by an equally large species, _M.
+anguillicaudatus_.
+
+   NEMACHILUS.--No erectile sub-orbital spine. Six barbels, none at
+   the mandible. Dorsal fin opposite to the ventrals.
+
+The greater number of Loaches belong to this genus; about fifty species
+are known from Europe and temperate Asia; such species as extend
+into tropical parts inhabit streams of high altitudes. Loaches are
+partial to fast-running streams with stony bottom, and exclusively
+animal feeders. In spite of their small size they are esteemed as food
+where they occur in sufficient abundance. The British species, _N.
+barbatulus_, is found all over Europe except Denmark and Scandinavia.
+
+   COBITIS.--Body more or less compressed, elongate; back not
+   arched. A small, erectile, bifid sub-orbital spine below the
+   eye. Six barbels only on the upper jaw. Dorsal fin inserted
+   opposite to ventrals. Caudal rounded or truncate.
+
+Only three species are known, of which _C. tænia_ occurs in Europe. It
+is scarce and very local in Great Britain.
+
+   BOTIA.--Body compressed, oblong; back more or less arched. Eyes
+   with a free circular eyelid; an erectile bifid sub-orbital
+   spine. Six barbels on the upper jaw, sometimes two others at the
+   mandibulary symphysis. Dorsal fin commencing in advance of the
+   root of the ventrals; caudal fin forked. Air-bladder consisting
+   of two divisions: the anterior enclosed in a partly osseous
+   capsule, the posterior free, floating in the abdominal cavity.
+
+  [Illustration: Fig. 276.--Botia rostrata. From Bengal.]
+
+This genus is more tropical than any of the preceding, and the majority
+of the species (eight in number) are finely coloured. The more elevated
+form of their body, and the imperfect ossification of the capsules of
+the air-bladder, the divisions of which are not side by side, but
+placed in the longitudinal axis of the body, indicate likewise that
+this genus is more adapted for still waters of the plains than for the
+currents of hill-streams.
+
+Other genera from tropical India are _Lepidocephalichthys_,
+_Acanthopsis_, _Oreonectes_ (hills near Hong-Kong), _Paramisgurnus_
+(Yan-tse-Kiang), _Lepidocephalus_, _Acanthophthalmus_, and _Apua_.
+
+
+                       FOURTH FAMILY--KNERIIDÆ.
+
+_Body scaly, head naked. Margin of the upper jaw formed by the
+intermaxillaries. Dorsal and anal fins short, the former belonging
+to the abdominal portion of the vertebral column. Teeth none, either
+in the mouth or pharynx. Barbels none. Stomach siphonal; no pyloric
+appendages. Pseudobranchiæ none. Branchiostegals three; air-bladder
+long, not divided. Ovaries closed._
+
+Small loach-like fishes from fresh waters of tropical Africa; two
+species only, _Kneria angolensis_ and _K. spekii_, are known.
+
+
+                      FIFTH FAMILY--CHARACINIDÆ.
+
+_Body covered with scales, head naked; barbels none. Margin of the
+upper jaw formed by the intermaxillaries in the middle and by the
+maxillaries laterally. Generally a small adipose fin behind the dorsal.
+Pyloric appendages more or less numerous; air-bladder transversely
+divided into two portions, and communicating with the organ of hearing
+by means of the auditory ossicles. Pseudobranchiæ none._
+
+The fishes of this family are confined to the fresh waters of Africa,
+and especially of tropical America, where they replace the Cyprinoids,
+with which family, however, they have but little in common as far as
+their structural characteristics are concerned. Their co-existence
+in Africa with Cyprinoids proves only that that continent is nearer
+to the original centre, from which the distribution of Cyprinoids
+commenced than tropical America. The family includes herbivorous as
+well as strictly carnivorous forms; some are toothless, whilst others
+possess a most formidable dentition. The family contains so many
+diversified forms as to render a subdivision into groups necessary.
+They have not yet been obtained in fossiliferous strata.
+
+I. ERYTHRININA.--_Adipose fin absent._
+
+The sixteen species of this group belong to the fauna of tropical
+America, and are referred to the genera _Macrodon_, _Erythrinus_,
+_Lebiasina_, _Nannostomus_, _Pyrrhulina_, and _Corynopoma_.
+
+II. CURIMATINA.--_A short dorsal and an adipose fin; dentition
+imperfect. Tropical America._
+
+   CURIMATUS.--Dorsal fin placed nearly in the middle of the body;
+   anal rather short or of moderate length; ventrals below the
+   dorsal. Body oblong or elevated, with the belly rounded or
+   flattened before the ventrals. Cleft of the mouth transverse,
+   lips none, margins of the jaws trenchant. No teeth whatever.
+   Intestinal tract very long and narrow.
+
+About twenty species are known, of rather small size.
+
+The other genera of this group have teeth, but they are either
+rudimentary or absent in some part of the jaws: _Prochilodus_,
+_Cænotropus_, _Hemiodus_, _Saccodon_, _Parodon_.
+
+III. CITHARININA.--_A rather long dorsal and an adipose fin; minute
+labial teeth. Tropical Africa._
+
+One genus only, _Citharinus_, with two species, is known. Common in the
+Nile, attaining to a length of three feet.
+
+IV. ANASTOMATINA.--_A short dorsal and an adipose fin; teeth in both
+jaws well developed; the gill-membranes grown to the isthmus; nasal
+openings remote from each other. Tropical America._
+
+   LEPORINUS.--Dorsal fin placed nearly in the middle of the length
+   of the body; anal short; ventrals below the dorsal. Body oblong,
+   covered with scales of moderate size; belly rounded. Cleft of
+   the mouth small, with the lips well developed; teeth in the
+   intermaxillary and mandible, few in number, flattened, with the
+   apex more or less truncated, and not serrated; the middle pair
+   of teeth is the longest in both jaws; palate toothless.
+
+This genus is generally distributed in the rivers east of the Andes;
+about twenty species are known, some of which, like _L. frederici_, _L.
+megalepis_, are very common. They are well marked by black bands or
+spots, and rarely grow to a length of two feet, being generally much
+smaller.--The other genera belonging to this group are _Anastomus_ and
+_Rhytiodus_.
+
+V. NANNOCHARACINA.--_A short dorsal and an adipose fin; teeth in both
+jaws well developed; notched incisors. The gill-membranes are grown to
+the isthmus. Nostrils close together._
+
+One genus, _Nannocharax_, with two species only, from the Nile and
+Gaboon; very small.
+
+VI. TETRAGONOPTERINA.--_A short dorsal and an adipose fin; the teeth
+in both jaws well developed, compressed, notched, or denticulated; the
+gill-membranes free from the isthmus, and the nasal openings close
+together. South America and Tropical Africa._
+
+   ALESTES.--The dorsal fin is placed in the middle of the length
+   of the body, above or behind the ventrals; anal fin rather
+   long. Body oblong, covered with scales of moderate or large
+   size; belly rounded. Cleft of the mouth rather small. Maxillary
+   teeth none; intermaxillary teeth in two series; those of the
+   front series more or less compressed, more or less distinctly
+   tricuspid; the teeth of the hinder series are broad, molar-like,
+   each armed with several pointed tubercles. Teeth in the
+   lower jaw in two series; those in the front series laterally
+   compressed, broader behind than in front; the hinder series is
+   composed of two conical teeth. All the teeth are strong, few in
+   number.
+
+Fourteen species from Tropical Africa; several inhabit the Nile, of
+which the “Raches” (_A. dentex_ and _A. kotschyi_) are the most common.
+
+   TETRAGONOPTERUS.--The dorsal fin is placed in the middle
+   of the length of the body, above or immediately behind the
+   ventrals; anal fin long. Body oblong or elevated, covered with
+   scales of moderate size; belly rounded. Cleft of the mouth of
+   moderate width. Anterior teeth strong, lateral teeth small.
+   Intermaxillary and mandibulary teeth subequal in size, with
+   a compressed and notched crown, the former in a double, the
+   latter in a single series; maxillary with a few teeth near its
+   articulation, rarely with the entire edge denticulated.
+
+Of all the genera of this family _Tetragonopterus_ is represented by
+the greatest number of species; about fifty are known. Some of them
+seem to have a very wide range, whilst others are merely local. All are
+of small size, rarely exceeding a length of eight inches.
+
+   CHIRODON.--Dorsal fin placed in the middle of the length of the
+   body, behind the ventrals; anal long or of moderate length. Body
+   oblong, covered with scales of moderate size; lateral line not
+   continued to the tail. Belly rounded before the ventrals. Cleft
+   of the mouth narrow, maxillary short. A single series of small
+   serrated teeth in the intermaxillary and mandibulary; maxillary
+   teeth none.
+
+  [Illustration: Fig. 277.--Chirodon alburnus.]
+
+Three species of small size from various parts of South America; the
+species figured is represented of the natural size, and comes from the
+Upper Amazons.
+
+   MEGALOBRYCON.--Dorsal fin placed in middle of the length of
+   the body, immediately behind the ventrals. Anal long. Abdomen
+   rounded in front of, and somewhat compressed behind, the
+   ventrals. Cleft of the mouth of moderate width. Teeth notched,
+   in a triple series in the intermaxillary, and in a single in the
+   maxillary and mandible; no other teeth behind the mandibulary
+   teeth or on the palate. Scales of moderate size, with the free
+   portion striated.
+
+One species from the Upper Amazons (_M. cephalus_). Specimens more
+than one foot long have been obtained.
+
+  [Illustration: Fig. 278.--Megalobrycon cephalus.]
+
+   GASTROPELECUS.--Dorsal fin placed behind the middle of the
+   length of the body, above the anal; anal long; pectoral long;
+   ventrals very small or rudimentary. Body strongly compressed,
+   with the thoracic region dilated into a sub-semicircular disk.
+   Scales of moderate size. Lateral line descending obliquely
+   backwards towards the origin of the anal fin. The lower profile
+   compressed into an acute ridge. Cleft of the mouth of moderate
+   width; teeth compressed, tricuspid, in one or two series in the
+   intermaxillary, and in a single in the mandible; maxillary with
+   a few minute conical teeth; palate toothless.
+
+Three specimens of this singular form are known from Brazil and the
+Guyanas; they are of very small size.
+
+The majority of the other genera belonging to this group are South
+American, viz. Piabucina, Scissor, _Pseudochalceus_, _Aphyocharax_,
+_Chalceus_, _Brycon_, _Chalcinopsis_, _Bryconops_, _Creagrutus_,
+_Chalcinus_, _Piabuca_, _Paragoniates_, and _Agoniates_; two only
+are African, viz. _Nannæthiops_, which represents the South American
+_Tetragonopterus_, and _Bryconæthiops_, which is allied to Brycon.
+
+VII. HYDROCYONINA.--_A short dorsal and an adipose fin_; _teeth in
+both jaws well developed and conical; gill membranes free from the
+isthmus; nasal openings close together. South America and Tropical
+Africa. Fishes of prey._
+
+   HYDROCYON.--The dorsal fin is in the middle of the length of the
+   body, above the ventrals; anal of moderate length. Body oblong,
+   compressed, covered with scales of moderate size; belly rounded.
+   Cleft of the mouth wide, without lips; the intermaxillaries and
+   mandibles are armed with strong pointed teeth, widely set and
+   few in number; they are received in notches of the opposite
+   jaw, and visible externally when the mouth is closed. Palate
+   toothless. Cheeks covered with the enlarged sub-orbital bones.
+   Orbit with an anterior and posterior adipose eyelid. Intestinal
+   tract short.
+
+Four species from Tropical Africa; two occur in the Nile, _H.
+forskalii_ being abundant, and well known by the names “Kelb el
+bahr” and “Kelb el moyeh.” Their formidable dentition renders them most
+destructive to other fishes; they grow to a length of four feet.
+
+   CYNODON.--Dorsal fin placed behind, or nearly in, the middle of
+   the length of the body, behind the ventrals; anal long. Head
+   and body compressed, oblong, the latter covered with very small
+   scales; belly compressed, keeled. Teeth in the intermaxillary,
+   maxillary, and mandible in a single series, conical, widely set,
+   of unequal size; a pair of very large canine teeth anteriorly
+   in the lower jaw, received in two grooves on the palate; palate
+   with patches of minute granulated teeth. The outer branchial
+   arch without gill-rakers, but with very short tubercles.
+
+Four species from Brazil and the Guyanas; they are as formidable fishes
+of prey as the preceding, and grow to the same size.
+
+With the exception of _Sarcodaces_, all the remaining genera of this
+group belong to the fauna of Tropical America, viz. _Anacyrtus_,
+_Hystricodon_, _Salminus_, _Oligosarcus_, _Xiphorhamphus_, and
+_Xiphostoma_.
+
+VIII. DISTICHODONTINA.--_Dorsal fin rather elongate; adipose fin
+present. Gill-membranes attached to the isthmus; belly rounded.
+Tropical Africa._
+
+The species, ten in number, belong to one genus only (_Distichodus_),
+well known on the Nile under the name of “Nefasch.” They grow to a
+considerable size, being sometimes four feet long and one and a half
+foot deep. They are used as food.
+
+IX. ICHTHYBORINA.--_An adipose fin; number of dorsal rays increased
+(12–17); gill-membranes free from the isthmus. Belly rounded; canine
+teeth. Tropical Africa._
+
+Two genera only: _Ichthyborus_ from the Nile, and _Phago_ from West
+Africa. Small fishes of very rare occurrence.
+
+X. CRENUCHINA.--_Dorsal fin rather elongate; an adipose fin.
+Gill-membranes free from the isthmus, with the belly rounded, and
+without canine teeth._
+
+This small group is represented in the Essequibo by a single species,
+_Crenuchus spilurus_, and by another in West Africa, _Xenocharax
+spilurus_.
+
+XI. SERRASALMONINA.--_Dorsal fin rather elongate; an adipose fin.
+Gill-membranes free from the isthmus; belly serrated. Tropical America._
+
+Although the fishes of this family do not attain any considerable size,
+the largest scarcely exceeding two feet in length, their voracity,
+fearlessness, and number renders them a perfect pest in many rivers of
+tropical America. In all, the teeth are strong, short, sharp, sometimes
+lobed incisors, arranged in one or more series; by means of them
+they cut off a mouthful of flesh as with a pair of scissors; and any
+animal falling into the water where these fishes abound is immediately
+attacked and cut in pieces in an incredibly short time. They assail
+persons entering the water, inflicting dangerous wounds before the
+victims are able to make their escape. In some localities it is
+scarcely possible to catch fishes with the hook and line, as the fish
+hooked is immediately attacked by the “Caribe” (as these fishes are
+called), and torn to pieces before it can be withdrawn from the water.
+The Caribes themselves are rarely hooked, as they snap the hook or
+cut the line. The smell of blood is said to attract at once thousands
+of these fishes to a spot. They are most abundant in the Brazils and
+Guyanas; some forty species are known, and referred to the genera
+_Mylesinus_, _Serrasalmo_, _Myletes_, and _Catoprion_.
+
+  [Illustration: Fig. 279.--Serrasalmo scapularis, from the Essequibo.]
+
+
+                     SIXTH FAMILY--CYPRINODONTIDÆ.
+
+_Head and body covered with scales; barbels none. Margin of the upper
+jaw formed by the intermaxillaries only. Teeth in both jaws; upper
+and lower pharyngeals with cardiform teeth. Adipose fin none; dorsal
+fin situated on the hinder half of the body. Stomach without blind
+sac; pyloric appendages none. Pseudobranchiæ none; air-bladder simple,
+without ossicula auditus._
+
+Small fishes, inhabiting fresh, brackish, and salt water of Southern
+Europe, Africa, Asia, and America. The majority are viviparous; and to
+facilitate copulation the anal fin of the adult male of many species
+is modified into a copulatory organ, which is probably (partially at
+least) introduced into the vulva of the female; but it is uncertain
+whether it serves to conduct the semen, or merely to give the male
+a firmer hold of the female during the act. Also secondary sexual
+differences are developed in the Cyprinodonts; the males are always
+the smaller, sometimes several times smaller than the females, quite
+diminutive; and they are perhaps the smallest fishes in existence. The
+fins generally are more developed in the males, and the coloration is
+frequently different also. Some species are carnivorous; others live
+on the organic substances mixed with mud. Fossil remains have been
+found in tertiary strata, all apparently referable to the existing
+genus _Cyprinodon_; they occur near Aix in Provence, in the marl
+of Gesso, St. Angelo, in the Brown coal near Bonn, near Frankfort,
+and in the freshwater-chalk of Oeningen. In the latter locality a
+_Poecilia_ occurs likewise.
+
+The genera can be divided into two groups:
+
+I. CYPRINODONTIDÆ CARNIVORÆ.--_The bones of each ramus of the mandible
+are firmly united; intestinal tract short, or but little convoluted.
+Carnivorous or insectivorous._
+
+   CYPRINODON.--Cleft of the mouth small, developed laterally and
+   horizontally. Snout short. Teeth of moderate size, incisor-like,
+   notched, in a single series. Scales rather large. Origin of the
+   anal fin behind that of the dorsal in both sexes, both fins
+   being larger in the male than in the female. Anal not modified
+   into a sexual organ.
+
+Seven species occur in the Mediterranean region, all of which seem
+able to live in briny springs or pools, the water of which contains a
+much greater percentage of salts than sea-water, as the brine-springs
+near the Dead Sea or in the Sahara. They are as little affected by
+the high temperature of some of these springs (91°), for instance
+of that at Sidi Ohkbar in the Sahara. Like other fishes living in
+limited localities or concealing themselves in mud, Cyprinodonts lose
+sometimes their ventral fins; such specimens have been described as
+_Tellia_. The species of the New World are less known than those
+of the Old, but not less numerous.
+
+Allied to Cyprinodon are _Fitzroyia_ from Monte Video, and _Characodon_
+from Central America.
+
+   HAPLOCHILUS.--Snout flat, both jaws being much depressed, and
+   armed with a narrow band of villiform teeth. Body oblong,
+   depressed anteriorly, compressed posteriorly. Dorsal fin short,
+   commencing behind the origin of the anal, which is more or less
+   elongate.
+
+Twenty species from the East Indies, tropical Africa, and temperate and
+tropical America.
+
+   FUNDULUS.--Cleft of the mouth of moderate width, developed
+   laterally and horizontally. Snout of moderate length. Teeth
+   in a narrow band, those of the outer series being largest,
+   conical. Scales of moderate size. Dorsal fin commencing before
+   or opposite the origin of the anal. Sexes not differentiated.
+
+“Killifish,” abundant in the New World, where about twenty species have
+been found; _F. heteroclitus_, _majalis_, _diaphanus_, being common on
+the Atlantic coast of the United States; from the Old World two species
+only are known, viz. _F. hispanicus_ from Spain, and _F. orthonotus_
+from the east coast of Africa. Allied to _Fundulus_ are the South
+American _Limnurgus_, _Lucania_, _Rivulus_, and _Cynolebias_.
+
+   ORESTIAS.--Ventral fins none. Cleft of the mouth of moderate
+   width, directed upwards, with the lower jaw prominent, and with
+   the upper protractile. Both jaws with a narrow band Of small
+   conical teeth. Scales rather small or of moderate size, those
+   on the head and upper part of the trunk frequently enlarged,
+   plate-like, and granulated. Dorsal and anal fins moderately
+   developed, opposite to each other. Sexes not differentiated by
+   modification of the anal fin. The gill-membranes of both sides
+   are united for a short distance, and not attached to the isthmus.
+
+Inhabitants of Lake Titicaca and other elevated sheets of water on the
+Cordilleras of Peru and Bolivia, between the 14th and 19th degrees of
+latitude, at an elevation of 13,000 and 14,000 feet above the level
+of the sea. Singularly, the fishes of this outlying genus attain to a
+greater size than any other members of this family, being about eight
+inches long and comparatively bulky. They are considered a delicacy.
+Six species.
+
+   JENYNSIA.--Cleft of the mouth small, developed laterally and
+   horizontally; snout not produced. Both jaws with a series of
+   tricuspid teeth of moderate size. Scales of moderate size.
+   The origin of the anal fin is, in both sexes, behind that of
+   the dorsal, although the anal of the male is modified into an
+   intromittent organ, in which scarcely any of the rays remain
+   distinct.
+
+One species from Maldonado.
+
+  [Illustration: Fig. 280.--Gambusia punctata, from Cuba. A. Male;
+  B. Female.]
+
+   GAMBUSIA.--Cleft of the mouth developed laterally and
+   horizontally. Snout not produced, with the lower jaw more or
+   less prominent. Both jaws with a band of teeth, those of the
+   outer series being strongest and conical. Scales rather large.
+   Origin of the anal fin more or less in advance of that of the
+   dorsal. Anal fin of the male modified into an intromittent organ
+   and much advanced.
+
+Eight species from the West Indies and the southern parts of South
+America.--Allied genera are the Central American _Pseudoxiphophorus_
+and _Belonesox_.
+
+   ANABLEPS.--Head broad and depressed, with the supraorbital
+   part very much raised. Body elongate, depressed anteriorly
+   and compressed posteriorly. Cleft of the mouth horizontal, of
+   moderate width, the mandible being short; upper jaw protractile.
+   Both jaws armed with a band of villiform teeth, those of the
+   outer series being largest and somewhat movable. The integuments
+   of the eye are divided into an upper and lower portion by a
+   dark-coloured transverse band of the conjunctiva; also the pupil
+   is completely divided into two by a pair of lobes projecting
+   from each side of the iris. Scales rather small or of moderate
+   size. Dorsal and anal fins short, the former behind the latter.
+   The anal fin of the male is modified into a thick and long scaly
+   conical organ with an orifice at its extremity.
+
+Three species from tropical America. They are the longest Cyprinodonts,
+attaining to the length of nearly twelve inches. Their peculiar habit
+of swimming with part of the head out of the water has been noticed
+above (p. 113).
+
+II. CYPRINODONTIDÆ LIMNOPHAGÆ.--_The bones of each ramus of the
+mandible are but loosely joined; intestinal tract with numerous
+circumvolutions. Sexes differentiated. Mud-eating. Tropical America._
+
+   POECILIA.--Cleft of the mouth small, transverse; mandible very
+   short. Both jaws with a narrow band of minute teeth. Scales
+   rather large. Origin of the anal fin generally nearly opposite
+   to that of the dorsal fin in the female, but in the male it is
+   modified into an intromittent organ and much advanced. Dorsal
+   fin short, with not more than eleven rays.
+
+Sixteen species.
+
+   MOLLIENESIA.--Differing from _Poecilia_ in having a larger
+   dorsal fin, with twelve or more rays.
+
+Five species. The males are most beautifully coloured, and their
+dorsal fin is much enlarged. In one species (_M. hellerii_), besides,
+the lower caudal rays of the mature male are prolonged into a long,
+sword-shaped, generally black and yellow appendage.
+
+Two other genera belong to this group: _Platypoecilus_ and _Girardinus_.
+
+
+                     SEVENTH FAMILY--HETEROPYGII.
+
+_Head naked; body covered with very small scales; barbels none.
+Margin of the upper jaw formed, by the intermaxillaries. Villiform
+teeth in the jaws and on the palate. Adipose fin none. Dorsal fin
+belonging to the caudal portion of the vertebral column, opposite to
+the anal. Ventral fins rudimentary or absent. Vent situated before the
+pectorals. Stomach coecal; pyloric appendages present. Pseudobranchiæ
+none; air-bladder deeply notched anteriorly._
+
+To this small family, which is closely allied to the Cyprinodonts and
+Umbridæ, belongs the famous Blind Fish of the Mammoth Cave in Kentucky,
+_Amblyopsis spelæus_. It is destitute of external eyes, and the
+body is colourless; although the eyes, with the optic nerve, are quite
+rudimentary, the optic lobes are as much developed as in fishes with
+perfect eyes. The loss of vision is compensated by the acuteness of
+its sense of hearing, as well as by a great number of tactile papillæ,
+arranged on transverse ridges on the head, and provided with nervous
+filaments coming from the fifth pair. The ovary is single, and the
+fish is viviparous, like the Cyprinodonts. It seems to occur in all
+the subterranean rivers that flow through the great limestone region
+underlying the carboniferous rocks in the central portion of the United
+States. As in _Cyprinodon_, so in this genus, specimens occur
+without ventral fins; they have been called _Typhlichthys_. The
+largest size to which _Amblyopsis_ grows is five inches.
+
+_Chologaster_ is closely allied, but provided with small external
+eyes; its body is coloured, but it is destitute of ventrals. It was
+found once in a rice field in South Carolina.
+
+   [See Tellkampf, Müll. Arch. 1844, p. 381; Packard and Putnam,
+   “The Mammoth Cave and its Inhabitants.” Salem. 1872. 8^o.]
+
+
+                        EIGHTH FAMILY--UMBRIDÆ.
+
+_Head and body covered with scales; barbels none. Margin of the upper
+jaw formed by the intermaxillaries mesially, and by the maxillaries
+laterally. Adipose fin none; the dorsal fin belongs partly to the
+abdominal portion of the vertebral column. Stomach siphonal; pyloric
+appendages none; pseudobranchiæ glandular, hidden; air-bladder
+simple._
+
+Two small species only are known: _Umbra krameri_ from Austria and
+Hungary, and _Umbra limi_, locally distributed in the United States;
+called “Hunds-fish” in Germany, “Dog-fish” or “Mud-fish” in America.
+
+
+                     NINTH FAMILY--SCOMBRESOCIDÆ.
+
+_Body covered with scales; a series of keeled scales along each side
+of the belly. Margin of the upper jaw formed by the intermaxillaries
+mesially, and by the maxillaries laterally. Lower pharyngeals united
+into a single bone. Dorsal fin opposite the anal, belonging to the
+caudal portion of the vertebral column. Adipose fin none. Air-bladder
+generally present, simple, sometimes cellular, without pneumatic
+duct. Pseudobranchiæ hidden, glandular. Stomach not distinct from the
+intestine, which is quite straight, without appendages._
+
+The fishes of this family are chiefly marine, some living in the open
+ocean, whilst others have become acclimatised in fresh water; many of
+the latter are viviparous, all the marine forms being oviparous. They
+are found in all the temperate and tropical zones. Carnivorous.
+
+This family is represented in the strata of Monte Bolca by rare remains
+of a fish named _Holosteus_, allied to _Belone_ or _Scombresox_, and
+by a species of _Belone_ in the miocene of Licata.
+
+   BELONE.--Both jaws are prolonged into a long slender beak. All
+   the dorsal and anal rays connected by membrane.
+
+The long upper jaw of the “Gar-pike” is formed by the intermaxillaries,
+which are united by a longitudinal suture. Both jaws are beset with
+asperities, and with a series of longer, conical-pointed, widely-set
+teeth. Skimming along the surface of the water, the Gar-pike seize
+with these long jaws small fish as a bird would seize them with its
+beak; but their gullet is narrow, so that they can swallow small fish
+only. They swim with an undulating motion of the body; although they
+are in constant activity, their progress through the water is much
+slower than that of the Mackerels, the shoals of which sometimes
+appear simultaneously with them on our coasts. Young specimens are
+frequently met in the open ocean; when very young their jaws are not
+prolonged, and during growth the lower jaw is much in advance of the
+upper, so that these young fishes resemble a _Hemirhamphus_. About
+fifty species are known from tropical and temperate seas, _Belone
+belone_ being a common fish on the British coast. Its bones, like
+those of all its congeners, are green; and therefore the fish, although
+good eating, is disliked by many persons. Some species attain a length
+of five feet.
+
+   SCOMBRESOX.--Both jaws are prolonged into a long slender beak. A
+   number of detached finlets behind the dorsal and anal fins.
+
+The “Saury” or “Skipper” resemble the Gar-pike, but the teeth in the
+jaws are minute; they seem to feed chiefly on soft pelagic animals. In
+their habits they are still more pelagic; and the young, in which the
+beak is still undeveloped, are met with everywhere in the open ocean,
+in the Atlantic as well as in the Pacific. The European species,
+_Sc. saurus_, is not rare on the British coast; four other species
+have been described, closely allied to _Sc. saurus_.
+
+   HEMIRHAMPHUS.--The lower jaw only is prolonged into a long
+   slender beak.
+
+In the young both jaws are short; the upper is never prolonged, the
+intermaxillaries forming a triangular, more or less convex, plate.
+The “Half-beaks” are common between and near the tropics; some forty
+species are known, none of which attain to the same length as the
+Gar-pike, scarcely ever exceeding a length of two feet. Some of the
+tropical species live in fresh water only; they are of small size and
+viviparous.
+
+   ARRHAMPHUS.--Mouth formed as in _Hemirhamphus_, except that the
+   lower jaw is not produced into a beak. Pectoral fins of moderate
+   length.
+
+One species (_A. sclerolepis_) from the coast of Queensland (not
+New Zealand); it may be regarded as a _Hemirhamphus_, with retarded
+development of the lower jaw.
+
+   EXOCOETUS.--Jaws short, intermaxillaries and maxillaries
+   separate. Teeth minute, rudimental, and sometimes absent. Body
+   moderately oblong, covered with rather large scales. Pectorals
+   very long, an organ of flying.
+
+  [Illustration: Fig. 281.--Flying Fish; Exocoetus callopterus.]
+
+Forty-four different kinds of “Flying-fishes” are known from tropical
+and sub-tropical seas; some have a very wide range, whilst others seem
+to remain within one particular part of the ocean; thus, the species
+figured, _E. callopterus_, has been hitherto found on the Pacific
+side of the isthmus of Panama only. Their usual length is about 10 or
+12 inches, but specimens of 18 inches have been caught. They always
+live in shoals, and their numbers at certain times and localities are
+immense; thus, at Barbadoes many boats engage in their capture, as
+they are excellent eating. The pectorals are in the various species of
+unequal length; in some they extend to the anal fin only; in others
+(and these are the best fliers) to the caudal. A few have curious,
+barbel-like appendages at the lower jaw, which may disappear with age
+or be persistent throughout life. The literature on the subject of
+Flying-fishes is very extensive, and great diversity of opinion exists
+among observers as regards the mode and power of their flight; but
+the most reliable agree that the fishes do not leave the water for
+the purpose of catching insects (!), and that they are unable to move
+their fins in the manner of a bat or bird, or to change voluntarily the
+direction of their flight, or to fly beyond a very limited distance.
+The most recent enquiries are those of K. Möbius (“Die Bewegungen
+der Fliegenden Fische durch die Luft,” Leip. 1878, 8vo), the chief
+results of which may be summed up thus: Flying-fish are more frequently
+observed in rough weather and in a disturbed sea than during calm; they
+dart out of the water when pursued by their enemies, or frightened
+by an approaching vessel, but frequently also without any apparent
+cause, as is also observed in many other fishes; and they rise without
+regard to the direction of the wind or waves. The fins are kept quietly
+distended, without any motion, except an occasional vibration caused
+by the air whenever the surface of the wing is parallel with the
+current of the wind. Their flight is rapid, but gradually decreasing
+in velocity, greatly exceeding that of a ship going 10 miles an hour,
+and a distance of 500 feet. Generally, it is longer when the fishes
+fly against than with or at an angle to the wind. Any vertical or
+horizontal deviation from a straight line is not caused at the will of
+the fish, but by currents of the air; thus they retain a horizontally
+straight course when flying with or against the wind, but are carried
+towards the right or left whenever the direction of the wind is at an
+angle with that of their flight. However, it sometimes happens that
+the fish during its flight immerses its caudal fin in the water, and
+by a stroke of its tail turns towards the right or left. In a calm the
+line of their flight is always also vertically straight, or rather
+parabolic, like the course of a projectile, but it may become undulated
+in a rough sea, when they are flying against the course of the waves;
+they then frequently overtop each wave, being carried over it by the
+pressure of the disturbed air. Flying-fishes often fall on board of
+vessels, but this never happens during a calm, or from the lee side,
+but during a breeze only, and from the weather side. In daytime they
+avoid a ship, flying away from it; but during the night, when they
+are unable to see, they frequently fly against the weather-board,
+where they are caught by the current of air, and carried upwards to a
+height of 20 feet above the surface of the water, while, under ordinary
+circumstances, they keep close to it. All these observations point
+clearly to the fact that any deflection from a straight course is due
+to external circumstances, and not to voluntary action on the part of
+the fish.
+
+
+                        TENTH FAMILY--ESOCIDÆ.
+
+_Body covered with scales; barbels none. Margin of the upper jaw
+formed by the intermaxillaries mesially, and by the maxillaries
+laterally. Adipose fin none; the dorsal fin belongs to the caudal
+portion of the vertebral column. Stomach without blind sac; pyloric
+appendages none. Pseudobranchiæ glandular, hidden; air-bladder simple;
+gill-opening very wide._
+
+This family includes one genus only, _Esox_, the “Pikes,” inhabitants
+of the fresh waters of the temperate parts of Europe, Asia, and
+America. The European species, _E. lucius_, inhabits all three
+continents, but the North American waters harbour five, or perhaps
+more, other species, of which the “Muskellunge,” or “Maskinonge” (_E.
+estor_) of the Great Lakes attains to the same large size as the common
+Pike. The other species are generally called “Pickerell” in the United
+States.
+
+  [Illustration: Fig. 282.--The Pike. (Esox lucius.)]
+
+Fossil Pike, belonging to the existing genus, have been found in the
+freshwater-chalk of Oeningen, and in the diluvial marl of Silesia.
+Remains of the common Pike occur in abundance in quaternary deposits.
+
+
+                      ELEVENTH FAMILY--GALAXIIDÆ.
+
+_Body naked, barbels none. Margin of the upper jaw chiefly formed
+by the intermaxillaries, which are short, and continued by a thick
+lip, behind which are the maxillaries. Belly rounded; adipose fin
+none; dorsal opposite to anal. Pyloric appendages in small number.
+Air-bladder large, simple; pseudobranchiæ none. The ova fall into the
+cavity of the abdomen before exclusion._
+
+Small freshwater fishes of the southern hemisphere, belonging to two
+genera, _Galaxias_ and _Neochanna_. Of the former genus five species
+are found in New Zealand, where this type is most developed, three in
+New South Wales, two in Tasmania, and four in the southern extremity
+of South America. Their native name in New Zealand is “Kokopu,” and
+they were dignified with the name of “Trout” by the settlers before the
+introduction of true Salmonidæ. They rarely exceed a length of eight
+inches. _Neochanna_ is a degraded form of _Galaxias_, from which it
+differs by the absence of ventral fins. This fish has hitherto been
+found only in burrows, which it excavates in clay or consolidated mud,
+at a distance from water.
+
+  [Illustration: Fig. 283.--Galaxias truttaceus, from Tasmania.]
+
+
+                      TWELFTH FAMILY--MORMYRIDÆ.
+
+_Body and tail scaly; head scaleless; barbels none. The margin of
+the upper jaw is formed in the middle by the intermaxillaries, which
+coalesce into a single bone, and laterally by the maxillaries. Sub-
+and inter-operculum present, the latter very small. On each side of
+the single parietal bone a cavity leading into the interior of the
+skull, and covered with a thin bony lamella. All the fins are well
+developed, in_ Mormyrus; _or caudal, anal, and ventral fins are
+absent, in_ Gymnarchus. _No adipose fin. Pseudobranchiæ none;
+gill-openings reduced to a short slit. Air-bladder simple. Two coeca
+pylorica behind the stomach._
+
+This family is characteristic of the freshwater fauna of tropical
+Africa. Of _Mormyrus_ (including _Hyperopisus_ and _Mormyrops_),
+fifty-one species are known, of which eleven occur in the Nile. Some
+attain a length of three or four feet, others remain small. Their flesh
+is said to have an excellent flavour. The species figured (and probably
+other allied species) was an object of veneration to the ancient
+Egyptians, and, therefore, frequently occurs in their emblematic
+inscriptions. They abstained from eating it because it was one of three
+different kinds of fishes accused of having devoured a member of the
+body of Osiris, which, therefore, Isis was unable to recover when she
+collected the rest of the scattered members of her husband.
+
+  [Illustration: Fig. 284.--Mormyrus oxyrhynchus.]
+
+The _Mormyri_ possess a singular organ on each side of the tail,
+without electric functions, but evidently representing a transitional
+condition from muscular substance to an electric organ. It is an oblong
+capsule divided into numerous compartments by vertical transverse
+septa, and containing a gelatinous substance. The _Mormyri_ differ
+much with regard to the extent of the dorsal and anal fins, the former
+sometimes occupying the greater portion of the length of the back,
+sometimes being much shorter and limited to the tail. In some the snout
+is short and obtuse, in others long and decurved, with or without
+appendage.
+
+Of _Gymnarchus_ one species only is known, _G. niloticus_, which occurs
+in the Nile and West African rivers, and attains a length of six
+feet. The form of its body is eel-like, and each jaw is armed with a
+series of incisor-like teeth. Like _Mormyrus_, _Gymnarchus_ possesses
+a pseudo-electric organ, thickest on the tail, tapering in front,
+and extending nearly to the head. It consists of four membranaceous
+tubes intimately connected with the surrounding muscles, and
+containing prismatic bodies arranged in the manner of a paternoster.
+The air-bladder of Gymnarchus is cellular, very extensible, and
+communicates with the dorsal side of the œsophagus by a duct possessing
+a sphincter.
+
+   [See _Erdl_, Münchner Gelehrte Anzeigen, 1846, xxiii., and
+   _Hyrtl_, Denkschr. Akad. Wiss. Wien. 1856. xii.]
+
+
+                  THIRTEENTH FAMILY--STERNOPTYCHIDÆ.
+
+_Body naked, or with very thin deciduous scales; barbels none. Margin
+of the upper jaw formed by the maxillary and intermaxillary, both
+of which are toothed; opercular apparatus not completely developed.
+Gill-opening very wide; pseudobranchiæ present or absent; air-bladder
+simple, if present. Adipose fin present, but generally rudimentary.
+Series of phosphorescent bodies along the lower parts. The eggs are
+enclosed in the sacs of the ovarium, and excluded by oviducts._
+
+Pelagic and Deep-sea fishes of small size.
+
+   STERNOPTYX.--Trunk much elevated and compressed, with the trunk
+   of the tail very short. Body covered with a silvery pigment,
+   without regular scales; series of phosphorescent spots run along
+   the lower side of the head, body, and tail. Cleft of the mouth
+   wide, vertical, with the lower jaw prominent. Jaws armed with
+   small teeth. Eyes rather large, and although lateral, directed
+   upwards and placed close together. Ventral fins very small. A
+   series of imbricate scutes runs along the abdomen, forming a
+   kind of serrature. The dorsal fin is short, and occupies about
+   the middle of the length of the fish; it is preceded by the
+   first commencement of the formation of a spinous dorsal, several
+   neural spines being prolonged beyond the dorsal muscle forming a
+   triangular osseous plate. Adipose fin rudimentary; anal short;
+   caudal forked.
+
+These small fishes are now and then picked up in the Mediterranean
+and Atlantic. According to the dredging-records of the “Challenger,”
+they and the allied genera _Argyropelecus_ and _Polyipnus_ would
+descend to depths of respectively 1100 and 2500 fathoms; but the form
+of their body and their whole organisation render this statement very
+improbable; they most likely live at a small depth during the daytime,
+coming to the surface at night, like many _Scopelus_.
+
+_Coccia_ and _Maurolicus_ are two other genera allied to the preceding.
+
+  [Illustration: Fig. 285.--Chauliodus sloanii.]
+
+   CHAULIODUS.--Body elongate, compressed, covered with exceedingly
+   thin and deciduous scales; series of luminous (phosphorescent)
+   spots run along the lower side of the head, body, and tail.
+   Head much compressed and elevated, with the bones thin, but
+   ossified, and with the opercular portion very narrow, the
+   interoperculum being rudimentary. Cleft of the mouth exceedingly
+   wide, the intermaxillary forming one half of the upper jaw.
+   Each intermaxillary with four long canine teeth; edge of the
+   maxillary finely denticulated; mandible with pointed, widely
+   set teeth, the anterior of which are exceedingly long; none of
+   the large teeth are received within the mouth. Palatine with a
+   single series of small pointed teeth; no teeth on the tongue.
+   Eye of moderate size. Pectoral and ventral fins well developed.
+   Dorsal fin anteriorly on the trunk, before the ventrals; adipose
+   fin small, sometimes fimbriated; anal short, rather close to
+   the caudal, which is forked. Gill-opening very wide, the outer
+   branchial arch extending forward to behind the symphysis of the
+   lower jaw; it has no gill-rakers. Branchiostegals numerous.
+
+This genus, of which one species only (_Ch. sloanii_) is known, is
+generally distributed over the great depths of the oceans, and does not
+appear to be scarce; it attains to a length of 12 inches, and must be
+one of the most formidable fishes of prey of the deep-sea.
+
+Allied genera are _Gonostoma_, _Photichthys_, and _Diplophos_, all of
+which have the teeth of much smaller size.
+
+
+                    FOURTEENTH FAMILY--STOMIATIDÆ.
+
+_Skin naked, or with exceedingly delicate scales; a hyoid barbel.
+Margin of the upper jaw formed by the intermaxillary and maxillary
+which are both toothed; opercular apparatus but little developed.
+Gill-opening very wide; pseudobranchiæ none. The eggs are enclosed in
+the sacs of the ovarium, and excluded by oviducts._
+
+Deep-sea fishes, descending to the greatest depths, characterised by
+their barbel and their formidable dentition.
+
+  [Illustration: Fig. 286.--_Astronesthes niger._ The white
+  spots in front of the eye are phosphorescent organs.]
+
+Some have two dorsal fins, the posterior of which is adipose; they
+belong to the genus _Astronesthes_, are the smallest of the family, and
+frequently met with in the Atlantic.
+
+The others--viz. _Stomias_, _Echiostoma_, _Malacosteus_, and
+_Bathyophis_, lack the adipose fin, the rayed dorsal being opposite to
+the anal. Of these the one longest known is
+
+   STOMIAS.--Body elongate, compressed, covered with exceedingly
+   fine and deciduous scales, which are scarcely imbricate, lying
+   in subhexagonal impressions; vent situated at no great distance
+   from the caudal fin. Head compressed, with the snout very short,
+   and with the cleft of the mouth very wide. Teeth pointed,
+   unequal in size, those of the intermaxillaries and of the
+   mandible being the longest; maxillary finely denticulated; vomer
+   with a pair of fangs; palatine bones and tongue with smaller
+   pointed teeth. Eye of moderate size. Opercular portion of the
+   head narrow. A fleshy barbel in the centre of the hyoid region.
+   Dorsal opposite the anal, close to the caudal; pectoral and
+   ventral fins feeble, the latter inserted behind the middle of
+   the length of the body. Series of phosphorescent dots run along
+   the lower side of the head, body, and tail. Gill-opening very
+   wide. Pyloric appendages none.
+
+Three species are known; beside specimens which were found floating on
+the surface, others have been dredged from depths varying between 450
+and 1800 fathoms.
+
+
+                     FIFTEENTH FAMILY--SALMONIDÆ.
+
+_Body generally covered with scales; head naked; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally. Belly rounded. A small adipose fin behind
+the dorsal. Pyloric appendages generally numerous, rarely absent.
+Air-bladder large, simple; pseudobranchiæ present. The ova fall into
+the cavity of the abdomen before exclusion._
+
+Inhabitants of the sea and freshwater; the majority of the marine
+genera are deep-sea forms. The freshwater forms are peculiar to the
+temperate and arctic zones of the Northern Hemisphere, one occurring
+in New Zealand; many freshwater species periodically or occasionally
+descending to the sea. One of the most valuable families of the class
+of fishes. No fossils of the freshwater forms are known; but of the
+marine genera, _Osmerus_ occurs in the greensand of Ibbenbusen,
+and in the schists of Glaris and Licata; a species of _Mallotus_,
+indistinguishable from the living _M. villosus_, occurs abundantly in
+nodules of clay of unknown geological age in Greenland. Other genera,
+as _Osmeroides_, _Acrognathus_, and _Aulolepis_, from the chalk of
+Lewes, belong to the same fauna as species of Beryx, and were probably
+deep-sea Salmonoids.
+
+   SALMO.--Body covered with small scales. Cleft of the mouth wide,
+   the maxillary extending to below or beyond the eye. Dentition
+   well developed; conical teeth in the jaw bones, on the vomer
+   and palatines, and on the tongue, none on the pterygoid bones.
+   Anal short, with less than fourteen rays. Pyloric appendages
+   numerous; ova large. Young specimens with dark cross-bands
+   (Parr-marks).
+
+We know of no other group of fishes which offers so many difficulties
+to the ichthyologist with regard to the distinction of the species
+as well as to certain points in their life-history, as this genus,
+although this may be partly due to the unusual attention which has been
+given to their study, and which has revealed an almost greater amount
+of unexplained facts than of satisfactory solutions of the questions
+raised. The almost infinite variations of these fishes are dependent
+on age, sex and sexual development, food, and the properties of the
+water. Some of the species interbreed, and the hybrids mix again with
+one of the parent species, thus producing an offspring more or less
+similar to the pure breed. The _coloration_ is, first of all, subject
+to variation; and consequently this character but rarely assists in
+distinguishing a species, there being not one which would show in all
+stages of development the same kind of coloration. The young of all the
+species are _barred_; and this is so constantly the case that it may
+be used as a generic or even as a family character, not being peculiar
+to _Salmo_ alone, but also to _Thymallus_ and probably to _Coregonus_.
+The number of bars is not quite constant, but the migratory Trout
+have two (and even three) more than the River-Trout. In some waters
+River-trout remain small, and frequently retain the Parr-marks all
+their lifetime; at certain seasons a new coat of scales overlays the
+Parr-marks, rendering them invisible for a time; but they reappear
+in time, or are distinct as soon as the scales are removed. When the
+Salmones have passed this “Parr” state, the coloration becomes much
+diversified. The males, especially during and immediately after the
+spawning time, are more intensely coloured and variegated than the
+females; specimens which have not attained to maturity retaining a
+brighter silvery colour, and being more similar to the female fish.
+Food appears to have less influence on the coloration of the outer
+parts than on that of the flesh; thus the more variegated specimens are
+frequently out of condition, whilst well-fed individuals with pinkish
+flesh are of a more uniform though bright coloration. Chemistry has
+not supplied us yet with an analysis of the substance which gives the
+pink colour to the flesh of many Salmonoids; but there is little doubt
+that it is identical with, and produced by, the red pigments of many
+salt- and freshwater Crustaceans, which form a favourite food of these
+fishes. The water has a marked influence on the colours; Trout with
+intense ocellated spots are generally found in clear rapid rivers, and
+in small open Alpine pools; in the large lakes with pebbly bottom the
+fish are bright silvery, and the ocellated spots are mixed with or
+replaced by X-shaped black spots; in pools or parts of lakes with muddy
+or peaty bottom, the trout are of a darker colour generally, and when
+enclosed in caves or holes, they may assume an almost uniform blackish
+coloration.
+
+The change of scales (that is, the rapid reproduction of the worn
+part of the scales) coincides in the migratory species with their
+sojourn in the sea. The renovated scales give them a bright silvery
+appearance, most of the spots disappearing or being overlaid and hidden
+by the silvery scales. Now, some of the species, like _S. fario_,
+inhabit all the different waters indicated, even brackish water, and,
+in consequence, we find a great variation of colour in one and the
+same species; others are more restricted in their habitat, like _S.
+salar_, _S. ferox_, etc., and, therefore, their coloration may be more
+precisely defined.
+
+With regard to _size_ the various species do not present an equal
+amount of variation. Size appears to depend on the abundance of food
+and the extent of the water. Thus, the Salmon and the different kinds
+of great Lake-trout do not appear to vary considerably in size, because
+they find the same conditions in all the localities inhabited by them.
+A widely spread species, however, like _S. fario_, when it inhabits
+a small mountain pool with scanty food, may never exceed a weight
+of eight ounces, whilst in a large lake or river, where it finds an
+abundance and variety of food, it attains to a weight of fourteen
+or sixteen pounds. Such large River-trout are frequently named and
+described as Salmon-trout, Bull-trout, etc. Further, in Salmones, as
+in the majority of fishes and tailed Batrachians, there is an innate
+diversity of growth in individuals hatched from the same spawn. Some
+grow rapidly and normally, others more slowly, and some remain dwarfed
+and stationary at a certain stage of development.
+
+The _proportions of the various parts of the body_ to one another vary
+exceedingly in one and the same species. Beside the usual changes from
+the young to the sexually mature form observed in all fishes, the snout
+undergoes an extraordinary amount of alteration of shape. In the mature
+male the intermaxillaries and the mandible are produced in various
+degrees, and the latter is frequently more or less bent upwards. Hence
+the males have the snout much more pointed and produced, and the entire
+head longer, than the females; with the intermaxillary bone the teeth,
+with which it is armed, are also enlarged, sometimes to four times the
+size of those of the females. And if this development of the front
+part of the head happens to be going on while the individual is able
+to obtain only a scanty supply of food, the usual proportions of the
+head and trunk are so altered that the species is very difficult to
+recognise. Barren male fish approach the females in the proportions of
+the head and body, but hybrid fishes do not differ in this respect from
+their parents. The abundance or scarcity of food, and the disposition
+or indisposition of the Salmonoids to feed, are other causes affecting
+the growth or fulness of the various parts of the body. In well-fed
+fishes the head is proportionally not only smaller but also shorter,
+and _vice versa_.
+
+The _fins_ vary to a certain degree. The variation in the number of
+the rays is inconsiderable and of no value for specific distinction.
+The caudal fin undergoes considerable changes of form with age,
+and dependency upon the sexual development. Young specimens of all
+species have this fin more or less deeply excised, so that the young
+of a species which has the caudal emarginate throughout life, is
+distinguished by a deeper incision of the fin, from the young of a
+species which has it truncate in the adult state. As the individuals of
+a species do not all attain to maturity at the same age and at the same
+size, and as mature individuals generally have the caudal less deeply
+excised than immature ones of the same age and size, it is evident that
+the variations in the form of the caudal are considerable and numerous,
+and that it is a very misleading character if due regard be not paid to
+the age and sexual development of the fish. Further, species inhabiting
+rapid streams as well as still waters show considerable variations in
+the form and length of all the fins; those individuals which live in
+rapid streams, being in almost constant motion and wearing off the
+delicate extremities of the fins, have the fin-rays comparatively
+shorter and stouter, and the fins of a more rounded form, particularly
+at the corners, than individuals inhabiting ponds or lakes. Moreover,
+one and the same individual may pass a part of its life in a lake, and
+enter a river at certain periods, thus changing the form of its fins
+almost periodically.
+
+Finally, to complete our enumeration of these variable characters, we
+must mention that in old males, during and after the spawning-season,
+the _skin_ on the back becomes thickened and spongy, so that the scales
+are quite invisible, being imbedded in the skin.
+
+       *       *       *       *       *
+
+After this cursory review of variable characters we pass on to those
+which are more constant, not subject to ready modification by external
+circumstances; and which, therefore, ought to be noticed in every
+description of a species of Salmo.
+
+1. _The form of the præoperculum of the adult fish._ The præoperculum
+is composed of a vertical (posterior) and horizontal (lower) part
+(limb), both meeting at a more or less rounded angle. The development
+of the lower limb is a very constant character; in some species (as
+in the Salmon) it is long, in others (_S. ferox_, _S. brachypoma_)
+exceedingly short. The adjoining woodcuts will readily show this
+difference.
+
+  [Illustration: Fig. 287.--Præoperculum of A. Salmo salar; B.
+  Salmo brachypoma.]
+
+In young specimens of all Salmonoids the præoperculum has a very short
+lower limb; but whilst in some species it lengthens with age, its
+development in a horizontal direction is arrested in others.
+
+2. _The width and strength of the maxillary of the adult fish._--To
+show this character in two distinct species, we have given woodcuts
+of the maxillaries of females (12 inches long) of _S. fario_ and _S.
+levenensis_ of the same size.
+
+  [Illustration: Fig. 288.--Maxillary of A. Salmo fario; B. Salmo
+  levenensis.]
+
+In young specimens of all Salmonoids the maxillary is comparatively
+shorter and broader, somewhat resembling that of _Coregonus_; yet this
+bone offers a valuable character for the determination of the young
+of some species; for instance, in a young _S. cambricus_ it extends
+scarcely to below the centre of the eye, whilst in _S. fario_ of the
+same size it reaches to, or even beyond, this point.
+
+  [Illustration: Fig. 289.--Vomerine teeth of Salmo salar (Salmon).
+  A. Side view. B. Lower view.]
+
+3. _The size of the teeth, those of the intermaxillaries excepted._
+
+4. _The arrangement, and the permanence or deciduousness of the
+vomerine teeth._--In some species the vomer is normally armed with
+a double or single series throughout life, although, of course, some
+of the teeth are frequently accidentally lost; in others, these teeth
+disappear gradually with age, the hinder ones first, so that finally
+the anterior only remain. In order to ascertain the arrangement of
+the teeth, it is necessary to remove the gengiva. Frequently the
+teeth stand in a distinctly double or single series, or they are
+placed alternately; but frequent irregularities occur which render
+the character vague, or even unsafe, so that some zoologists have
+rejected it entirely as unreliable. However, when a greater number of
+individuals really belonging to the same species are examined, a pretty
+safe conclusion may be arrived at as regards the arrangement of the
+teeth.
+
+  [Illustration: Fig. 290.--Vomerine teeth of Salmo fario, lower
+  view.]
+
+  [Illustration: Fig. 291.--Vomerine teeth of a Charr, side view.]
+
+5. _The form of the caudal fin_ in specimens of a given size, age,
+and sexual development.
+
+6. _A great development of the pectoral fins_, when constant in
+individuals from the same locality.
+
+7. _The size of the scales_, as indicated by the number of transverse
+rows above the lateral line: one of the most constant characters.
+
+8. _The number of vertebræ._--Considering the great number of
+vertebræ in Salmonoids the constancy of this character is truly
+surprising. An excess or a diminution of the normal number by two, is
+of rare occurrence, and generally to be explained by the fact that
+one vertebra has been abnormally divided into two, two such vertebræ
+being considerably smaller than the others; or, on the other hand,
+that two have merged into one centrum, which is then unusually large,
+and provided with two neural spines. We have seen one case only, in
+which three vertebræ were united. The number of vertebræ can be easily
+ascertained in specimens destined for preservation in spirits, by an
+incision made along one side of the fish, a little above the lateral
+line.
+
+9. _The number of pyloric appendages._--There can be no doubt that
+this character may materially assist in fixing a species. We shall see
+that in some species it varies from 30 to 50; but in others, as in the
+Salmon and Charr, it has been found very constant (see Fig. 56, p.
+131). If unexpected variations occur, their cause may be found in a
+partial confluence of the cæca, as we have observed that specimens of
+_S. levenensis_ (a species normally with from 70 to 90 cæca), had
+those appendages of unusual width when the normal number was diminished.
+
+       *       *       *       *       *
+
+We have mentioned above that many points in the _life-history_ of
+the Salmonoids still remain very obscure:--
+
+1. Johnson, a correspondent of Willughby (“Hist. Pisc.,” p. 194), had
+already expressed his belief that the different Salmonoids interbreed;
+and this view has since been shared by many who have observed these
+fishes in nature. Hybrids between the Sewin (_S. cambricus_) and
+the River Trout (_S. fario_) were numerous in the Rhymney and other
+rivers of South Wales, before Salmonoids were almost exterminated by
+the pollutions allowed to pass into those streams, and so variable
+in their characters that the passage from one species to the other
+could be demonstrated in an almost unbroken series, which might
+induce some naturalists to regard both species as identical. Abundant
+evidence of a similar character has accumulated, showing the frequent
+occurrence of hybrids between _S. fario_ and _S. trutta_; hybrids
+between _S. fario_ and species of Charr have been abundantly bred by
+continental pisciculturists. In some rivers the conditions appear to
+be more favourable to hybridism than in others, in which hybrids are
+of comparatively rare occurrence. Hybrids between the Salmon and some
+other species are very scarce everywhere. The hybrids are sexually as
+much developed as the pure breed, but nothing whatever is known of
+their further propagation and progeny.
+
+2. Siebold has shown that some individuals of every species are not
+sexually developed, and that such individuals differ also externally
+from those normally developed. However, he appears to have gone too
+far when he stated that this state of sterility extends over the whole
+existence of such individuals, and that, therefore, the external
+peculiarities also remain permanent throughout life. According to
+Widegren this sterility is merely a temporary immaturity, and a part of
+the individuals arrive at a full sexual development at a later or much
+later period than others. To this we may add that many Salmonoids cease
+to propagate their species after a certain age, and that all so called
+overgrown individuals (that is, specimens much exceeding the usual size
+of the species) are barren. Externally they retain the normal specific
+characters.
+
+The Salmon offers a most remarkable instance of irregularity as
+regards the age at which the individuals arrive at maturity. Shaw
+has demonstrated, in the most conclusive manner, that those small
+Salmonoids, which are generally called Parr, are the offspring of the
+Salmon, and that many males, from 7 to 8 inches long, have their sexual
+organs fully developed, and that their milt has all the impregnating
+properties of the seminal fluid of a much older and larger fish. That
+this Parr is not a distinct species--as has been again maintained by
+Couch--is further proved by the circumstance that these sexually mature
+Parr are absolutely identical in their zoological characters with the
+immature Parr, which are undoubtedly young Salmon, and that no Parr
+has ever been found with mature ova. But whether these Parr produce
+normal Salmon, impregnating the ova of female salmon, or mingle with
+the River-trout, or whether they continue to grow and propagate their
+species as fully developed Salmon, are questions which remain to be
+answered. We may only add that, as far as we know, barren old Salmon
+are extremely scarce.
+
+3. The question whether any of the migratory species can be retained
+by artificial means in fresh water, and finally accommodate themselves
+to a permanent sojourn therein, must be negatived for the present.
+Several instances of successful experiments made for this purpose
+have been brought forward; but all these accounts are open to serious
+doubts, inasmuch as they do not afford us sufficient proof that
+the young fish introduced into ponds were really young migratory
+Salmonoids, or that the full-grown specimens were identical with those
+introduced, and not hybrids or non-migratory Trout of a somewhat
+altered appearance in consequence of the change of their locality.
+We have seen the experiment tried at two places in South Wales, and
+in both cases the Salmon and the pure Sewin died when not allowed to
+return to the sea. On the other hand, hybrid fishes from the Sewin and
+the Trout survived the experiment, and continued to grow in a pond
+perfectly shut up from communication with the sea. In that locality
+neither those hybrids nor the trout spawn.
+
+4. Although the majority of the mature individuals of a migratory
+species ascend a river at a certain fixed time before the commencement
+of spawning, others enter the freshwater at a much earlier period,
+either singly or in small troops; and many appear to return to the sea
+before they reascend at the time of the regular immigration. It is
+not improbable that one and the same individual may change the salt-
+or freshwater several times in the year. However, this is the case in
+certain rivers only, for instance, in those falling into the Moray
+Firth; in others one immigration only is known to occur. The cause of
+the irregular ascents previous to the autumnal ascents is unknown. A
+part, at least, of the hybrid fishes retain the migratory instinct; but
+it is not known whether sterile individuals accompany the others in
+their migrations.
+
+5. It is said that the migratory species invariably return to the river
+in which they are bred. Experiments have shown that this is normally
+the case; but a small proportion appear to stray so far away from
+their native place as to be unable to find their way back. Almost every
+year Salmon and Sea-trout in the Grilse-state make their appearance at
+the mouth of the Thames (where the migrating Salmonoids have become
+extinct for many years), ready to reascend and to restock this river as
+soon as its poisoned water shall be sufficiently purified to allow them
+a passage.
+
+6. There has been much dispute about the time required for the growth
+of Salmonoids. The numerous and apparently contradictory observations
+tend to show that there is a great amount of variation even among
+individuals of the same origin living under the same circumstances,
+some of them growing much more quickly than others, and being ready to
+descend to the sea twelve months before their brethren. The cause of
+this irregularity is not explained. On the other hand, when we consider
+the fibrous condition of the Salmonoid skeleton, which is much less
+solid, and more wanting in calcareous substance, than that of the
+majority of Teleosteous fishes, we shall be quite prepared to adopt the
+truth of the observation that the young Salmonoids return to the fresh
+water, after a few months sojourn in the sea, and after having feasted
+on nourishing Crustaceans, Sand-eels, etc., with their former weight in
+ounces increased to pounds.
+
+7. Liability to variation in form indicates that an animal can adapt
+itself to a variety of circumstances; therefore, such species as show
+the greatest pliability in this respect, are those which most recommend
+themselves for domestication and acclimatisation within certain
+climatic limits. Thus, the River-trout or Sea-trout were very proper
+subjects for those eminently successful attempts to establish them in
+similar latitudes of the Southern Hemisphere, whilst the attempt of
+transferring them into the low hill-streams of India ended (as could be
+foreseen) in a total failure. Those two species must now be considered
+to be fully acclimatised in Tasmania and New Zealand, and with but
+little protection may be expected to hold their own in the freshwaters
+of those colonies. Whether the acclimatisation of the Salmon will be
+in the end equally and permanently successful, remains to be seen.
+The true _S. salar_ is not subject to variation, and is very
+sensitive to any change of external conditions, and to every kind of
+interference with its economy. The fourth species, with which attempts
+of acclimatisation in Southern Australia have been made, is a migratory
+Salmon from the Sacramento river in California. This experiment is
+still in progress, and believed to be promising of success. It will be
+a most curious problem to ascertain, how much the original characters
+and habits of those species will be affected by their transference to
+so distant a part of the globe. At present it would be too hazardous
+to offer an opinion on this point, especially as it is a fact that
+numerous cross-breeds have been introduced into, and reared in,
+Tasmania, which must more or less interfere with the characters of the
+pure breeds.
+
+It is apparent, from the foregoing remarks, that the distinction
+of the various species of Salmonidæ is a matter of considerable
+difficulty, and that there is scope for great diversity of opinion.
+At any rate it is only by a close, long-continued study, and constant
+comparison of specimens of various ages and from various localities,
+that one is enabled to find a guide through the labyrinth of confusing
+variations. However, it is a significant fact that the very same
+characters by which we are enabled to distinguish European species
+occur again, though in an exaggerated form, in American Salmonoids
+(which everybody will admit to be of distinct species), and therefore
+our faith in them necessarily becomes strengthened. In accordance with
+acknowledged principles in zoology, forms which differ from their
+congeners by a combination of two or more of constant characters, are
+to be distinguished under distinct specific names. Most likely they
+have been derived, at a not very remote period, from common ancestors,
+but the question of their specific distinctness is no more affected
+by this consideration than the question whether _Salmo_ and
+_Coregonus_ are distinct genera. Whenever the zoologist observes
+two forms distinguished by peculiarities of organisation, such as
+cannot be conceived to be the effects of an external or internal cause,
+disappearing with the disappearance of that cause, and which forms
+have been propagated and are being propagated uniformly through all
+the generations within the limits of our observations, and are yet
+most probably to be propagated during the existence of mankind, he is
+obliged to describe these forms as distinct, and they will commonly be
+called species.
+
+The species of the genus _Salmo_ are inhabitants of the temperate
+and arctic zones of the Northern Hemisphere; the species are most
+abundant in the northern parts of the temperate zone, becoming scarcer
+beyond the Arctic circle, and in the warmer parts towards the south.
+The southernmost points in which Salmones are found, are, on the
+American continent, the rivers falling into the head of the Californian
+Gulf, and in the Old World the mountain rivers of the Atlas and Hindu
+Kush. The Salmones from those localities are migratory Trout in the New
+World, non-migratory and small in the Old. Those species which range
+to the highest latitudes (lat. 82°) belong to the division of Charr, a
+group which generally are more intolerant of a moderate temperature,
+than real Trout. The genus is subdivided into
+
+   _a. Salmones_--Salmon and Trout--with teeth on the body of the
+   vomer as well as its head (see Figs. 289 and 290).
+
+   _b. Salvelini_--Charr--with teeth on the head of the vomer only
+   (see Fig. 291).
+
+  [Illustration: Fig. 292.--Salmo brachypoma.]
+
+Of the host of species (the majority of which is unfortunately very
+insufficiently characterised) we enumerate the following:--[45]
+
+
+                            _a._ SALMONES.
+
+   1. _S. salar_ (Salmon; Lachs or Salm; Saumon) (Fig. 6, p. 43).
+   The Salmon can generally be readily recognised, but there are
+   instances in which the identification of specimens is doubtful,
+   and in which the following characters (besides others) will be
+   of great assistance. The tail is covered with relatively large
+   scales, there being constantly eleven, or sometimes twelve in a
+   transverse series running from behind the adipose fin forwards
+   to the lateral line, whilst there are from thirteen to fifteen
+   in the different kinds of Sea-trout and River-trout. The number
+   of pyloric appendages (see Fig. 56, p. 131) is great, generally
+   between 60 and 70, more rarely falling to 53 or rising to 77.
+   The body of the vomer is armed with a single series of small
+   teeth, which at an early age are gradually lost from behind
+   towards the front, so that half-grown and old individuals have
+   only a few (1–4) left. The Salmon inhabits temperate Europe
+   southwards to 43° N. lat., and is not found in any of the rivers
+   falling into the Mediterranean. In the New World its southern
+   boundary is 41° N. lat.
+
+   2. _S. trutta_ (Sea-trout, Salmon-trout).[46]--Especially
+   numerous in North Britain.
+
+   3. _S. cambricus_ (Sewin).--Wales, South of England, Ireland,
+   Norway, and Denmark.
+
+   4. _S. fario_ (Common River-trout).
+
+   5. _S. macrostigma_ (Algeria).
+
+   6. _S. lemanus_ (Lake of Geneva).
+
+   7. _S. brachypoma._--A migratory species from the rivers Forth,
+   Tweed, and Ouse.
+
+   8. _S. gallivensis_ (Galway Sea-trout).
+
+   9. _S. orcadensis._--A non-migratory trout from Lough Stennis,
+   in the Orkney Islands.
+
+   10. _S. ferox._--The great Lake-trout of North Britain, Wales,
+   and Ireland.
+
+   11. _S. stomachicus_ (the Gillaroo of Ireland).
+
+   12. _S. nigripinnis_ from mountain-pools of Wales.
+
+   13. _S. levenensis_ (Lochleven Trout).
+
+   14. _S. oxi_ from the rivers of the Hindu Kush.
+
+   15. _S. purpuratus_ from the Pacific coast of Asia and North
+   America.
+
+   16. _S. macrostoma._--Japan.
+
+   17. _S. namaycush._--The great Lake-trout of North America.
+
+
+                        _b._ SALVELINI: Charr.
+
+   1. _S. umbla._--The “Ombre chevalier” of the Swiss lakes.
+
+   2. _S. salvelinus._--The “Sælbling” of the Alpine lakes of
+   Bavaria and Austria.
+
+   3. _S. alpinus._--The common Northern Charr, growing to a length
+   of four feet, and migratory.
+
+   4. _S. killinensis._--The Loch Killin Charr, Inverness-shire.
+
+   5. _S. willughbii._--The Loch Windermere Charr.
+
+   6. _S. perisii._--The “Torgoch” of Wales.
+
+   7. _S. grayi._--The “Freshwater Herring” of Lough Melvin,
+   Ireland.
+
+   8. _S. colii._--Charr of Loughs Eske and Dan.
+
+   9. _S. hucho._--The “Huchen” of the Danube, growing to the size
+   of the Salmon.
+
+   10. _S. alipes_ from lakes in Boothia Felix and Greenland.
+
+   11. _S. arcturus._--The most northern species from 82° lat.
+
+   12. _S. fontinalis._--The common “Brook-trout” of the United
+   States.
+
+   13. _S. oquassa._--A lake species from the State of Maine.
+
+_Oncorhynchus_ differs from _Salmo_ only in the increased number of
+anal rays, which are more than fourteen. All the species are migratory,
+ascending American and Asiatic rivers flowing into the Pacific. The
+Californian Salmon (_O. quinnat?_) belongs to this genus.
+
+Other allied genera are _Brachymystax_ and _Luciotrutta_.
+
+   PLECOGLOSSUS.--Body covered with very small scales. Cleft of the
+   mouth wide; maxillary long. Dentition feeble; intermaxillaries
+   with a few small, conical, pointed teeth; the teeth of the
+   maxillaries and mandibles are broad, truncated, lamellated
+   and serrated, movable, seated in a fold of the skin. The
+   mandibles terminate each in a small knob, and are not jointed
+   at the symphysis. The mucous membrane in the interior of the
+   mouth--between the terminal halves of the mandibles--forms a
+   peculiar organ, being raised into folds, with a pair of pouches
+   in front and a single one behind. Tongue very small, with minute
+   teeth, its apical part being toothless; palate apparently
+   without teeth.
+
+A small aberrant form of Freshwater-Salmonoids abundantly found in
+Japan and the Island of Formosa.
+
+   OSMERUS.--Body covered with scales of moderate size. Cleft of
+   the mouth wide; maxillary long, extending to, or nearly to, the
+   hind margin of the orbit. Dentition strong; intermaxillary and
+   maxillary teeth small, much smaller than those of the mandible.
+   Vomer with a transverse series of teeth, several of which are
+   large, fang-like; a series of conical teeth along the palatine
+   and pterygoid bones. Tongue with very strong fang-like teeth
+   anteriorly, and with several longitudinal series of smaller
+   ones posteriorly. Pectoral fins moderately developed. Pyloric
+   appendages very short, in small number; ova small.
+
+The “Smelt” (_O. eperlanus_) is common on many places of the coasts of
+Northern Europe and America. In the sea it grows to a length of eight
+inches; but, singularly, it frequently migrates from the sea into
+rivers and lakes, where its growth is very much retarded. That this
+habit is one of very old date, is evident from the fact that this small
+freshwater form occurs, and is fully acclimatised in lakes which have
+now no open communication with the sea. And still more singularly, this
+same habit, with the same result, has been observed in the Smelt of New
+Zealand (_Retropinna richardsonii_). The Smelt is considered a delicacy
+in Europe, as well as in America, where the same species occurs. Two
+other allied genera, _Hypomesus_ and _Thaleichthys_, are found on the
+Pacific coast of North America, the latter being caught in immense
+numbers, and known by the name “Eulachon” and “Oulachan;” it is so fat,
+that it is equally used as food and as candle.
+
+   MALLOTUS.--Body covered with minute scales, which are
+   somewhat larger along the lateral line and along each side
+   of the belly; in mature males these scales become elongate,
+   lanceolate, densely tiled, with free projecting points, forming
+   villous bands. Cleft of the mouth wide; maxillary very thin,
+   lamelliform, extending to below the middle of the eye. Lower jaw
+   the longer, partly received between the maxillaries. Dentition
+   very feeble; the teeth forming single series; only the teeth on
+   the tongue are somewhat larger and disposed in an elliptical
+   patch. Pectoral fins large, horizontal, with broad base. Pyloric
+   appendages very short, in small number; ova small.
+
+The “Capelin” (_M. villosus_) is found on the Arctic coasts of
+America and of Kamtschatka. It is caught in immense numbers by the
+natives, who consume it fresh, or dry it for use in the winter. Its
+length does not exceed nine inches.
+
+   COREGONUS.--Body covered with scales of moderate size. Cleft of
+   the mouth small; maxillary broad, short or of moderate length,
+   not extending behind the orbit. Teeth, if present, extremely
+   minute and deciduous. Dorsal fin of moderate length; caudal
+   deeply forked. Ova small.
+
+  [Illustration: Fig. 293.--Coregonus oxyrhynchus.]
+
+  [Illustration: Fig. 294.--Head of Coregonus oxyrhynchus.]
+
+The majority of the species, of which more than forty are known, are
+lacustrine species; and comparatively few are subject to periodical
+migrations to the sea, like _Salmo_. They are confined to the northern
+parts of temperate Europe, Asia, and North America. Their distribution
+is local, but sometimes three and more species are found in the same
+lake. They abound in every lake and river of the northern parts of
+North America, and are known by the name of “White-fish.” They are of
+vital importance to some tribes of the native population. The European
+_C. oxyrhynchus_ is as much a marine as a freshwater species. In the
+British Islands several small species occur, viz. _C. clupeoides_, the
+“Gwyniad,” “Schelly,” or “Powen” from the great lakes; _C. vandesius_,
+the “Vendace” of Lochmaben; and _C. pollan_, the “Pollan” of the Irish
+lakes. The latter is brought in quantities to Belfast market during
+the season, that is, at the time when it rises from the depths of
+Lough Neagh to deposit its spawn near the shore. Thomson says that in
+September 1834 some 17,000 were taken there at three or four draughts
+of the net. Some of the species of the continent of Europe and America
+attain to a much larger size than the British species, viz. to a length
+of two feet.
+
+  [Illustration: Fig. 295.--Coregonus clupeoides.]
+
+   THYMALLUS.--Principally distinguished from _Coregonus_ by its
+   long many-rayed dorsal fin.
+
+“Graylings”--five species, inhabiting clear streams of the north of
+Europe, Asia, and North America. The best known are the “Poisson bleu”
+of the Canadian voyageurs (_Th. signifer_), and the European
+Grayling (_T. vulgaris_).
+
+   SALANX.--Body elongate, compressed, naked or covered with
+   small, exceedingly fine, deciduous scales. Head elongate and
+   much depressed, terminating in a long, flat, pointed snout. Eye
+   small. Cleft of the mouth wide; jaws and palatine bones with
+   conical teeth, some of the intermaxillaries and mandibles being
+   enlarged; no teeth on the vomer; tongue with a single series of
+   curved teeth. Dorsal fin placed far behind the ventrals, but in
+   front of the anal; anal long; adipose fin small; caudal forked.
+   Pseudobranchiæ well developed; air-bladder none. The entire
+   alimentary canal straight, without bend; pyloric appendages
+   none. Ova small.
+
+This small, transparent, or whitish fish _(S. chinensis_) is well
+known at Canton and other places of the coast of China as “White-bait,”
+and considered a delicacy. It is evidently a fish which lives at a
+considerable depth in the sea, and approaches the coast only at certain
+seasons.
+
+Finally, this family is represented in the deep sea by three genera,
+_Argentina_, _Microstoma_, and _Bathylagus_, of which the two former
+live at moderate depths, and have been known for a long time, whilst
+the last was discovered during the “Challenger” expedition in the
+Atlantic and Antarctic Oceans at depths of 1950 and 2040 fathoms. As
+_Argentina_ is sometimes found in the North Atlantic, and even near the
+British coasts, we give its principal characters.
+
+   ARGENTINA.--Scales rather large; cleft of the mouth small;
+   intermaxillaries and maxillaries very short, not extending
+   to below the orbit. Eye large. Jaws without teeth; an arched
+   series of minute teeth across the head of the vomer and on the
+   fore part of the palatines; tongue armed with a series of small
+   curved teeth on each side. Dorsal fin short, in advance of the
+   ventrals; caudal deeply forked. Pseudobranchiæ well developed.
+   Pyloric appendages in moderate numbers. Ova small.
+
+Four species are known, of which _A. silus_ and _A. hebridica_ have
+been found occasionally on the North British, and, more frequently,
+on the Norwegian coast. The other species are from the Mediterranean.
+Attaining to a length of 18 inches.
+
+
+                     SIXTEENTH FAMILY--PERCOPSIDÆ.
+
+_Body covered with ctenoid scales; head naked. Margin of the upper
+jaw formed by the intermaxillaries only; opercular apparatus complete.
+Barbels none. Gill-openings wide. Adipose fin present._
+
+One genus and species only (_Percopsis guttatus_); interesting as
+having the general characters of Salmonoids, but the mouth and scales
+of a Percoid. Freshwaters of the northern United States.
+
+
+                  SEVENTEENTH FAMILY--HAPLOCHITONIDÆ.
+
+_Body naked or scaly (cycloid). Margin of the upper jaw formed
+by the intermaxillary; opercular apparatus complete. Barbels none.
+Gill-opening wide; pseudobranchiæ. Air-bladder simple. Adipose fin
+present. Ovaries laminated; the eggs fall into the cavity of the
+abdomen, there being no oviduct. Pyloric appendages none._
+
+  [Illustration: Fig. 296.--Prototroctes oxyrhynchus, New Zealand.]
+
+Freshwater-fishes which represent the Salmonoids in the southern
+hemisphere. Two genera only are known. _Haplochiton_ (Fig. 104, p. 250)
+abundant in lakes and the streams falling into the Straits of Magelhæn
+and in the rivers of Chile and the Falkland Islands. It has the general
+appearance of a Trout, but is naked. _Prototroctes_, with the habit of
+a _Coregonus_, scaly, and provided with minute teeth; one species (_P.
+maræna_) is common in South Australia, the other (_P. oxyrhynchus_) in
+New Zealand. The settlers in these colonies call them Grayling; the
+Maori name of the second species is “Upokororo.”
+
+
+                   EIGHTEENTH FAMILY--GONORHYNCHIDÆ.
+
+_Head and body entirely covered with spiny scales; mouth with
+barbels. Margin of the upper jaw formed by the intermaxillary, which,
+although short, is continued downwards as a thick lip, situated in
+front of the maxillary. Adipose fin none; the dorsal fin is opposite to
+the ventrals, and short, like the anal. Stomach simple, without blind
+sac; pyloric appendages in small number. Pseudobranchiæ; air-bladder
+absent. Gill-openings narrow._
+
+  [Illustration: Fig. 297.--Gonorhynchus greyi.]
+
+  [Illustration: Fig. 298.--Scale of Gonorhynchus greyi.]
+
+One genus and species only (_Gonorhynchus greyi_) is known; it is a
+semi-pelagic fish, not very rare off the Cape of Good Hope, and in the
+Australian and Japanese seas. From 12 to 18 inches long. The colonists
+in New Zealand name it “Sand-eel,” as it frequents bays with sandy
+bottom. It is eaten.
+
+
+                    NINETEENTH FAMILY--HYODONTIDÆ.
+
+_Body covered with cycloid scales; head naked; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally, the latter being articulated to the end of the
+former. Opercular apparatus complete. Adipose fin none; the dorsal
+fin belongs to the caudal portion of the vertebral column. Stomach
+horseshoe-shaped, without blind sac; intestine short; one pyloric
+appendage. Pseudobranchiæ none; air-bladder simple. Gill-openings wide.
+The ova fall into the abdominal cavity before exclusion._
+
+One genus and species only (_Hyodon tergisus_) is known, generally
+called “Moon-eye.” It is abundant in the western streams and great
+lakes of North America. From 12 to 18 inches long.
+
+
+                    TWENTIETH FAMILY--PANTODONTIDÆ.
+
+_Body covered with large cycloid scales; sides of the head osseous.
+Margin of the upper jaw formed by the single intermaxillary mesially,
+and by the maxillaries laterally. The dorsal fin belongs to the caudal
+portion of the vertebral column, is short, opposite and similar to the
+anal. Gill-openings wide; gill-covers consisting of a præoperculum
+and operculum only. Branchiostegals numerous. Pseudobranchiæ none;
+air-bladder simple. Stomach without coecal sac; one pyloric appendage.
+Sexual organs with a duct._
+
+A small freshwater-fish (_Pantodon buchholzi_), singularly alike to a
+Cyprinodont, from the west coast of Africa.
+
+
+                  TWENTY-FIRST FAMILY--OSTEOGLOSSIDÆ.
+
+_Body covered with large hard scales, composed of pieces like
+mosaic. Head scaleless; its integuments nearly entirely replaced by
+bone; lateral line composed of wide openings of the mucus-duct. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally. The dorsal fin belongs to the caudal portion of
+the vertebral column, is opposite and very similar to the anal fin;
+both approximate to the rounded caudal (with which they are abnormally
+confluent). Gill-openings wide; pseudobranchiæ none; air-bladder simple
+or cellular. Stomach without coecal sac; pyloric appendages two._
+
+Large freshwater-fishes of the tropics, whose singular geographical
+distribution has been noticed above (p. 223).
+
+   OSTEOGLOSSUM.--Cleft of the mouth very wide, oblique, with the
+   lower jaw prominent. A pair of barbels at the lower jaw. Abdomen
+   trenchant. Bands of rasp-like teeth on the vomer, palatine and
+   pterygoid bones, on the tongue and hyoid. Pectoral fins elongate.
+
+_O. bicirrhosum_ from Brazil and Guyana, _O. formosum_ from Borneo and
+Sumatra, _O. leichardti_ from Queensland.
+
+   ARAPAIMA.--Cleft of the mouth wide, with the lower jaw
+   prominent; barbels none. Abdomen rounded. Jaws with an outer
+   series of small conical teeth; broad bands of rasp-like teeth
+   on the vomer, palatines, pterygoids, sphenoid, os linguale, and
+   hyoid. Pectoral fins of moderate length.
+
+  [Illustration: Fig. 299.--Arapaima gigas.]
+
+The largest freshwater Teleostean known, exceeding a length of 15 feet
+and a weight of 400 pounds. It is common in the large rivers of Brazil
+and the Guyanas, and esteemed as an article of food. When salted it is
+exported in large quantities from the inland fisheries to the seaports.
+
+   HETEROTIS.--Cleft of the mouth rather small, with the jaws
+   subequal; barbels none. A single series of small teeth in the
+   jaws; pterygoids and hyoid with a patch of small conical teeth;
+   none on the vomer or palatines.
+
+This fish (_H. niloticus_), which is not uncommon in the Upper Nile and
+the West African rivers, exhibits several anatomical peculiarities. The
+fourth branchial arch supports a spiral accessory organ, the function
+of which is still unexplained. The air-bladder is cellular, and the
+stomach consists of a membranous and a muscular portion.
+
+
+                    TWENTY-SECOND FAMILY--CLUPEIDÆ.
+
+_Body covered with scales; head naked; barbels none. Abdomen
+frequently compressed into a serrated edge. Margin of the upper jaw
+formed by the intermaxillaries mesially, and by the maxillaries
+laterally; maxillaries composed of at least three movable pieces.
+Opercular apparatus complete. Adipose fin none. Dorsal not elongate;
+anal sometimes very long. Stomach with a blind sac; pyloric appendages
+numerous. Gill-apparatus much developed, the gill-openings being
+generally very wide. Pseudobranchiæ generally present. Air-bladder more
+or less simple._
+
+The family of “Herrings” is probably unsurpassed by any other in the
+number of individuals, although others comprise a much greater variety
+of species. The Herrings are principally coast-fishes, or, at least, do
+not go far from the shore; none belong to the deep-sea fauna; scarcely
+any have pelagic habits, but many enter or live in fresh waters
+communicating with the sea. They are spread over all the temperate
+and tropical zones. Fossil remains of Herrings are numerous, but the
+pertinence of some of the genera to this family is open to serious
+doubts, as the remains are too fragmentary to allow of determining
+whether they belong to Salmonoids or Clupeoids. Therefore, Agassiz
+comprised both families in one--_Halecidæ_. Many of the remains
+belong to recent genera, which are readily recognised, as _Clupea_,
+_Engraulis_ and _Chanos_, principally from the schists of Glaris and
+Licata, from Monte Bolca and the Lebanon. Others, like _Thrissopater_,
+from the Gault at Folkestone, _Leptosomus_, _Opisthopteryx_,
+_Spaniodon_, from the chalk and tertiary formations, can be readily
+associated with recent genera. But the majority do not show an apparent
+affinity to the present fauna. Thus, _Halec_ from the chalk of Bohemia,
+_Platinx_ and _Coelogaster_ from Monte Bolca, _Rhinellus_ from Monte
+Bolca and Mount Lebanon, _Scombroclupea_, with finlets behind the
+anal, from the Lebanon and Comen, and _Crossognathus_ from tertiary
+Swiss formations, allied to _Megalops_, _Spathodactylus_ from the same
+locality, and _Chirocentrites_ from Mount Lebanon, etc. Finally, a
+genus recently discovered in tertiary formations of Northern Italy,
+_Hemitrichas_, has been classed with the Clupeoids, from which,
+however, it differs by having two short dorsal fins, so that it must
+be considered, without doubt, to be the representative of a distinct
+family.
+
+   ENGRAULIS (including CETENGRAULIS).--Scales large or of moderate
+   size. Snout more or less conical, projecting beyond the lower
+   jaw. Teeth small or rudimentary. Intermaxillaries very small,
+   hidden; maxillary long, attached to the cheek by a scarcely
+   distensible membrane. Anal fin of moderate or great length.
+   Branchiostegals short, from nine to fourteen in number.
+
+Not less than forty-three different species of “Anchovies” are known
+from temperate and tropical seas. They exhibit marked differences in
+the length of their maxillary bone, which sometimes does not reach the
+gill-opening, whilst in other species it extends far beyond it; and in
+the number of their anal rays, which varies from 20 to 80. Some have
+the upper pectoral ray prolonged into a filament, thus leading towards
+the succeeding genus, _Coilia_. The majority are recognised, besides,
+by their peculiar structure, by a broad silvery, lateral band, similar
+to that observed in the Atherines. The most celebrated Anchovy is
+_E. encrasicholus_, very plentiful in the Mediterranean, but rarely
+wandering northwards. It is the species which, preserved in salt,
+is exported to all parts of the world, although similarly lucrative
+fisheries of Anchovies might be established in Tasmania where the same
+species occurs, in Chile, China, Japan, California, at Buenos Ayres,
+each of which countries possesses Anchovies by no means inferior to the
+Mediterranean species.
+
+   COILIA.--Body terminating in a long tapering tail. Scales of
+   moderate size. Snout and jaws as in _Engraulis_. Anal fin
+   exceedingly long, confluent with the caudal. The two or three
+   upper pectoral rays are much prolonged, and their branches form
+   four, six, or seven filaments.
+
+  [Illustration: Fig. 300.--Coilia clupeoides.]
+
+Ten species from Indian and Chinese seas.
+
+   CHATOËSSUS.--Body compressed; abdomen serrated. Scales of
+   moderate size. Snout obtuse, or obtusely conical, more or less
+   projecting beyond the cleft of the mouth, which is narrow, more
+   or less transverse. Maxillary joined to the ethmoid, its upper
+   portion being behind the intermaxillary. Teeth none. Anal fin
+   rather long; dorsal opposite to the ventrals, or to the space
+   between ventrals and anal. Gill-membranes entirely separate;
+   branchial arches forming two angles, one pointing forward and
+   the other backwards; the fourth branchial arch with an accessory
+   organ; branchiostegals of moderate length, five or six in number.
+
+Ten species from the coasts, brackish and fresh waters of Central
+America (one species ranges to New York), Australia, the East Indies,
+and Japan.
+
+   CLUPEA.--Body compressed, with the abdomen serrated, the
+   serrature extending forwards to the thorax. Scales of moderate
+   or large, rarely of small size. Upper jaw not projecting beyond
+   the lower. Cleft of the mouth of moderate width. Teeth, if
+   present, rudimentary and deciduous. Anal fin of moderate extent,
+   with less than thirty rays; dorsal fin opposite to the ventrals.
+   Caudal forked.
+
+This genus comprises more than sixty different species, the
+geographical distribution of which coincides with that of the family.
+The majority are of greater or less utility to man, but a few tropical
+species (_C. thrissa_, _C. venenosa_, and others) acquire, probably
+from their food, highly poisonous properties, so as to endanger the
+life of persons eating them. The most noteworthy species are--
+
+1. _C. harengus_ (the “Herring”).--It is readily recognised by having
+an ovate patch of very small teeth on the vomer. D. 17–20. A. 16–18.
+L. lat. 53–59. Vert. 56. Gill-cover smooth, without radiating ridges.
+It inhabits, in incredible numbers, the German Ocean, the northern
+parts of the Atlantic, and the seas north of Asia. The Herring of the
+Atlantic coasts of North America is identical with that of Europe. A
+second species has been supposed to exist on the British coast (_C.
+leachii_), but it comprises only individuals of a smaller size, the
+produce of an early or late spawn. Also the so-called “White-bait” is
+not a distinct species, but consists chiefly of the fry or the young
+of herrings, and is obtained “in perfection” at localities where these
+small fishes find an abundance of food, as in the estuary of the Thames.
+
+   [Separate accounts on the Herring may be found in Cuvier
+   and Valenciennes, “Hist. nat. des Poissons,” vol. xx.; J.
+   M. Mitchell, “The Herring, its Natural History and National
+   Importance,” Edinb. 1864, 8vo; P. Neucrantz, “De Harengo,”
+   Lübeck, 1654; J. S. Dodd, “Essay towards a Natural History
+   of the Herring,” Lond. 1768, 8vo; Bock, “Versuch einer
+   vollstændigen Natur-und Handels-Geschichte des Hærings,”
+   Königsberg, 1769, 8vo.]
+
+2. _C. mirabilis._--The Herring of the North Pacific.
+
+3. _C. sprattus._--The “Sprat.” Without vomerine teeth. D. 15–18.
+A. 17–20. L. lat. 47–48. Vert. 47–49. Gill-cover, smooth, without
+radiating ridges. Abundant on the Atlantic coasts of Europe.
+
+4. _C. thrissa._--One of the most common West Indian fishes,
+distinguished by the last dorsal ray being prolonged into a filament.
+Hyrtl has discovered a small accessory branchial organ in this species.
+
+5. _C. alosa._--The “Shad” or “Allice Shad,” with very fine and
+long gill-rakers, from 60 to 80 on the horizontal part of the outer
+branchial arch, and with one or more black lateral blotches. Coasts of
+Europe, ascending rivers.
+
+6. _C. finta._--The “Shad” or “Twaite Shad,” with stout osseous
+gill-rakers, from 21 to 27 on the horizontal part of the outer
+branchial arch, and spotted like the preceding species. Coasts of
+Europe, ascending rivers, and found in abundance in the Nile.
+
+7. _C. menhaden._--The “Mossbanker,” common on the Atlantic coasts
+of the United States. The economic value of this fish is surpassed
+in America only by that of the Gadoids, and derived chiefly from its
+use as bait for other fishes, and from the oil extracted from it, the
+annual yield of the latter exceeding that of the whale (from American
+Fisheries). The refuse of the oil factories supplies a material of much
+value for artificial manures.
+
+   [See G. Brown Goode, “The Natural and Economical History of the
+   American Menhaden,” in U.S. Commission of Fish and Fisheries,
+   Part V., Washington, 1879, 8vo.]
+
+8. _C. sapidissima._--The American Shad, abundant, and an important
+food-fish on the Atlantic coasts of North America. Spawns in fresh
+water.
+
+9. _C. mattowocca._--The “Gaspereau” or “Ale-wife,” common on the
+Atlantic coasts of North America, ascending into freshwater in early
+spring, and spawning in ponds and lakes.
+
+10. _C. pilchardus._--The “Pilchard” or the “Sardine,” equally
+abundant in the British Channel, on the coast of Portugal, and in
+the Mediterranean, and readily recognised by radiating ridges on the
+operculum, descending towards the sub-operculum.
+
+11. _C. sagax._--Representing the Pilchard in the Pacific, and found in
+equally large shoals on the coasts of California, Chile, New Zealand,
+and Japan.
+
+12. _C. toli._--The subject of a very extensive fishery on the coast
+of Sumatra for the sake of its roes, which are salted and exported to
+China, the dried fish themselves being sent into the interior of the
+island. The fish is called “Trubu” by the Malays, about 18 inches long,
+and it is said that between fourteen and fifteen millions are caught
+annually.
+
+13. _C. scombrina._--The “Oil-Sardine” of the eastern coast of the
+Indian Peninsula.
+
+       *       *       *       *       *
+
+Other, but less important genera of Clupeoids with serrated
+abdomen, are _Clupeoides_, _Pellonula_, _Clupeichthys_, _Pellona_,
+_Pristigaster_, and _Chirocentrodon_ (these three last with very small
+or without any ventral fins).
+
+   ALBULA.--Body oblong, moderately compressed; abdomen flat.
+   Scales of moderate size, adherent; lateral line distinct. Eyes
+   covered with a broad annular adipose membrane. Snout pointed,
+   the upper jaw projecting beyond the lower. Mouth inferior, of
+   moderate width, with villiform teeth; intermaxillary juxtaposed
+   to the upper anterior edge of the maxillary. Dorsal fin opposite
+   to the ventrals; anal fin shorter than dorsal. Gill-membranes
+   entirely separate, with numerous branchiostegals.
+
+One species only (_A. conorhynchus_), ranging over all tropical
+and sub-tropical seas, and very common in many localities near the
+coasts. It grows to a length of from two to three feet, and is not
+valued as food.
+
+   ELOPS.--Body rather elongate, moderately compressed; abdomen
+   flat. Scales small, adherent; lateral line distinct. A narrow
+   osseous lamella, attached to the mandibulary symphysis, covers
+   the part between the mandibles. Snout pointed; mouth wide,
+   anterior; intermaxillary short, maxillary forming the lateral
+   part of the mouth. Bands of villiform teeth in the jaws, on the
+   vomer, palatine and pterygoid bones, on the tongue, and on the
+   base of the skull. Dorsal fin opposite to ventrals; anal rather
+   shorter than dorsal. Gill-membranes entirely separate, with very
+   numerous branchiostegals.
+
+Two species, of which one, _E. saurus_, is, like the preceding fish,
+spread over all tropical and sub-tropical seas; it exceeds a length of
+three feet, and is not esteemed as food.
+
+  [Illustration: Fig. 301.--Elops saurus.]
+
+   MEGALOPS.--Body oblong, compressed, abdomen flat. Scales large,
+   adherent; lateral line distinct. A narrow osseous lamella,
+   attached to the mandibulary symphysis, between the mandibles.
+   Snout obtusely conical; mouth anterior, lower jaw prominent;
+   intermaxillary short; maxillary forming the lateral part of
+   the mouth. Bands of villiform teeth in the jaws, on the vomer,
+   palatine and pterygoid bones, on the tongue and on the base
+   of the skull. Dorsal fin opposite to, or immediately behind,
+   the ventrals; anal rather larger than dorsal. Gill-membranes
+   entirely separate, with numerous branchiostegals. Pseudobranchiæ
+   none.
+
+Two species, one belonging to the Indo-Pacific (_M. cyprinoides_),
+the other to the Atlantic (_M. thrissoides_); they are the largest
+fishes of this family, exceeding a length of five feet, and excellent
+eating. Young specimens enter freely fresh waters.
+
+   CHANOS.--Body oblong, compressed; abdomen flat. Scales small,
+   striated, adherent; lateral line distinct. Snout depressed;
+   mouth small, anterior, transverse, the lower jaw with a small
+   symphysial tubercle. Intermaxillary in juxtaposition to the
+   upper anterior edge of maxillary. Teeth none. Dorsal fin
+   opposite to the ventrals; anal small, shorter than dorsal;
+   caudal deeply forked. Gill-membranes entirely united below, and
+   free from the isthmus. Branchiostegals four, long. An accessory
+   branchial organ in a cavity behind the gill-cavity proper.
+   Air-bladder divided by a constriction into an anterior and
+   posterior portion. Mucous membrane of the œsophagus raised in a
+   spiral fold. Intestine with many convolutions.
+
+Two species from the Indo-Pacific, of which _Ch. salmoneus_ is
+extremely common; it enters fresh waters, and exceeds a length of four
+feet; its flesh is highly esteemed. The accessory branchial organ and
+the skeleton have been described by _Müller_, “Bau und Grenzen der
+Ganoiden,” p. 75; and by _Hyrtl_, “Denkschr. Ak. Wiss. Wien.” xxi.
+1883, p. 1.
+
+       *       *       *       *       *
+
+  [Illustration: Fig. 302.--Chanos salmoneus.]
+
+The remaining genera belonging to this family are _Spratelloides_,
+_Dussumieria_, and _Etrumeus_, which together form a small group,
+distinguished by an anterior and lateral mouth, by the upper jaw not
+overlapping the lower, by a rounded abdomen, and by lacking the gular
+plate of some of the preceding genera.
+
+
+                 TWENTY-THIRD FAMILY--BATHYTHRISSIDÆ.
+
+_Body oblong, with rounded abdomen, covered with cycloid scales;
+head naked; barbels none. Margin of the upper jaw formed by the
+intermaxillaries mesially, and by the maxillaries laterally. Opercular
+apparatus complete. Adipose fin none; dorsal fin much elongate, many
+rayed; anal fin short. Stomach with a blind sac; pyloric appendages
+numerous. Gill-apparatus well developed; pseudobranchiæ; gill-openings
+wide; an air-bladder. Ova very small; ovaries without duct._
+
+One genus and species only (_Bathythrissa dorsalis_) from deep water
+(350 fathoms) off the coast of Japan. This remarkable fish has the
+appearance of a _Coregonus_, and attains to a length of two feet.
+Nothing is known of its osteology, but possibly a fossil genus from the
+Gyps of Montmartre; _Notæus_, which has also a long dorsal fin, may
+prove to belong to the same family.
+
+
+                 TWENTY-FOURTH FAMILY--CHIROCENTRIDÆ.
+
+_Body covered with thin, deciduous scales; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by
+the maxillaries laterally, both bones being firmly united, in
+juxtaposition. Opercular apparatus complete. Adipose fin none; the
+dorsal fin belongs to the caudal portion of the vertebral column.
+Stomach with a blind sac; intestine short, the mucous membrane
+forming a spiral fold; pyloric appendages none. Pseudobranchiæ none;
+air-bladder incompletely divided into cells; gill-opening wide._
+
+One genus and species only (_Chirocentrus dorab_) is known, which
+is common in the Indian Ocean, and attains to a length of about
+three feet; it is not esteemed as food. Remains of fishes similar to
+_Chirocentrus_ are found in the marl slates of Padang, in Sumatra.
+
+
+                 TWENTY-FIFTH FAMILY--ALEPOCEPHALIDÆ.
+
+_Body with or without scales; head naked; barbels none. Margin of the
+upper jaw formed by the intermaxillaries and maxillaries, the former
+being placed along the upper anterior edge of the latter. Opercular
+apparatus complete. Adipose fin none; the dorsal fin belongs to the
+caudal portion of the vertebral column. Stomach curved, without blind
+sac; pyloric appendages in moderate number. Pseudobranchiæ; air-bladder
+absent. Gill-openings very wide._
+
+Before the voyage of the “Challenger” one species only of this
+family was known, _Alepocephalus rostratus_, a rare fish from the
+Mediterranean; now, four genera with seven species are known, and there
+is no doubt that this family is one of the most characteristic, and
+will prove to be one of the most generally distributed forms, of the
+deep-sea. Their vertical range varies between 345 (_Xenodermichthys_)
+and 2150 (_Bathytroctes_) fathoms. They approach the Salmonoids, but
+lack invariably the adipose fin. Their dentition is very feeble; their
+eye large; bones thin. Coloration black.
+
+   ALEPOCEPHALUS has thin cycloid scales; a mouth of moderate
+   width, and no teeth on the maxillary.
+
+   BATHYTROCTES has cycloid scales, a wide mouth, and teeth on the
+   maxillary as well as intermaxillary.
+
+   PLATYTROCTES has small keeled scales and no ventrals.
+
+   XENODERMICHTHYS with fine nodules instead of scales.
+
+
+                   TWENTY-SIXTH FAMILY--NOTOPTERIDÆ.
+
+_Head and body scaly; barbels none. Margin of the upper jaw formed
+by the intermaxillaries mesially, and by the maxillaries laterally.
+Opercular apparatus incomplete. Tail prolonged, tapering. Adipose fin
+none. Dorsal short, belonging to the caudal portion of the vertebral
+column; anal very long. Stomach without blind sac; two pyloric
+appendages. Pseudo__branchiae none; air-bladder present, divided
+in the interior. The ova fall into the cavity of the abdomen before
+exclusion. On each side a parieto-mastoid cavity leading into the
+interior of the skull._
+
+One genus only (_Notopterus_) with five species which inhabit fresh
+waters of the East Indies and West Africa. Well-preserved remains
+of this genus occur in the marl slates of Padang, in Sumatra. Their
+air-bladder is divided into several compartments, and terminates in two
+horns anteriorly and posteriorly, the anterior horns being in direct
+connection with the auditory organ.
+
+
+                  TWENTY-SEVENTH FAMILY--HALOSAURIDÆ.
+
+_Body covered with cycloid scales; head scaly; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally. Opercular apparatus incomplete. Adipose fin
+none. The short dorsal belongs to the abdominal part of the vertebral
+column; anal very long. Stomach with a blind sac; intestine short;
+pyloric appendages in moderate number. Pseudobranchiæ none. Air-bladder
+large, simple; gill-openings wide. Ovaries closed._
+
+The only genus belonging to this family was discovered by the Madeiran
+ichthyologist Johnson, in 1863; but since then the naturalists of the
+“Challenger” expedition have added four other species, showing that
+this type is a deep-sea form and widely distributed; the specimens were
+dredged in depths varying from 560 to 2750 fathoms.
+
+
+                 TWENTY-EIGHTH FAMILY--HOPLOPLEURIDÆ.
+
+_Body generally with four series of subtriangular scutes, and with
+intermediate scale-like smaller ones. One (?) dorsal only; head long,
+with the jaws produced._
+
+_Extinct_; developed in the chalk and extending into tertiary
+formations: _Dercetis_ (with the upper jaw longest), _Leptotrachelus_,
+_Pelargorhynchus_, _Plinthophorus_, _Saurorhamphus_ (with the lower jaw
+longest), _Eurypholis_; _Ischyrocephalus_ (?). The latter genus, from
+cretaceous formations of Westphalia, is said to have two dorsal fins.
+
+
+                    TWENTY-NINTH FAMILY--GYMNOTIDÆ.
+
+_Head scaleless; barbels none. Body elongate, eel-shaped. Margin
+of the upper jaw formed in the middle by the intermaxillaries, and
+laterally by the maxillaries. Dorsal fin absent or reduced to an
+adipose strip; caudal generally absent, the tail terminating in a
+point. Anal fin exceedingly long. Ventrals none. Extremity of the
+tapering tail capable of being reproduced. Vent situated at, or at a
+short distance behind, the throat. Humeral arch attached to the skull.
+Ribs well developed. Gill-openings rather narrow. Air-bladder present,
+double. Stomach with a cæcal sac and pyloric appendages. Ovaries with
+oviducts._
+
+Eel-like freshwater fishes from Tropical America.
+
+   STERNARCHUS.--Tail terminating in a distinct small caudal fin.
+   Teeth small. A rudimentary dorsal fin is indicated by an adipose
+   band fitting into a groove on the back of the tail; it is easily
+   detached, so as to appear as a thong-like appendage fixed in
+   front. Branchiostegals four.
+
+Eight species, some have the snout compressed and of moderate length,
+like _St. Bonapartii_ from the River Amazons; others have it produced
+into a long tube, as St. oxyrhynchus from the Essequibo.
+
+   RHAMPHICHTHYS.--Caudal fin none; teeth none; no trace of a
+   dorsal fin. No free orbital margin.
+
+Six species, of which, again, some have a tubiform snout, whilst in the
+others it is short.
+
+   STERNOPYGUS.--Caudal fin none; no trace of a dorsal fin. Both
+   jaws with small villiform teeth; similar teeth on each side of
+   the palate. Body scaly.
+
+Four species, very common, and growing to a length of 30 inches.
+
+   CARAPUS.--Caudal fin none; no trace of a dorsal fin. A series of
+   conical teeth in each jaw. Anterior nostrils, wide in the upper
+   lip. Body scaly.
+
+One species (_C. fasciatus_) extremely common, and found all over
+tropical America, east of the Andes, from 18 to 24 inches long.
+
+   GYMNOTUS.--Caudal and dorsal fins absent; anal extending to the
+   end of the tail. Scales none. Teeth conical, in a single series.
+   Eyes exceedingly small.
+
+The “Electric Eel” is the most powerful of electric fishes, growing to
+a length of six feet, and extremely abundant in certain localities of
+Brazil and the Guyanas. The electric organ consists of two pairs of
+longitudinal bodies, situated immediately below the skin, above the
+muscles; one pair on the back of the tail, and the other pair along
+the anal fin. Each fasciculus is composed of flat partitions or septa,
+with transverse divisions between them. The outer edge of the septa
+appear in nearly parallel lines in the direction of the longitudinal
+axis of the body, and consist of thin membranes, which are easily torn;
+they serve the same purpose as the columns in the analogous organ
+of the Torpedo, making the walls or abutments for the perpendicular
+and transverse dissepiments, which are exceedingly numerous, and so
+closely aggregated as to seem almost in contact. The minute prismatic
+cells, intercepted between these two sorts of plates, contain a
+gelatinous matter; the septa are about one-thirtieth of an inch from
+each other, and one inch in length contains a series of 240 cells,
+giving an enormous surface to the electric organs. The whole apparatus
+is supplied with more than 200 nerves, which are the continuations of
+the rami anteriores of the spinal nerves. In their course they give out
+branches to the muscles of the back, and to the skin of the animal.
+In the Gymnotus, as in the Torpedo, the nerves supplying the electric
+organs are much larger than those bestowed on any part for the purposes
+of sensation or movement.
+
+The graphic description by Humboldt of the capture of Electric Eels
+by horses driven into the water, which would receive the electric
+discharges and thus exhaust the fishes, seems to rest either on the
+imagination of some person who told it to the great traveller or on
+some isolated incident. Recent travellers have not been able to verify
+it even in the same parts of the country where the practice was said to
+exist.
+
+
+                    THIRTIETH FAMILY--SYMBRANCHIDÆ.
+
+_Body elongate, naked or covered with minute scales; barbels none.
+Margin of the upper jaw formed by the intermaxillaries only, the well
+developed maxillaries lying behind and parallel to them. Paired fins
+none. Vertical fins rudimentary, reduced to more or less distinct
+cutaneous folds. Vent situated at a, great distance behind the head.
+Ribs present. Gill-openings confluent into one slit situated on the
+ventral surface. Air-bladder none. Stomach without cæcal sac or pyloric
+appendages. Ovaries with oviducts._
+
+The fishes of this family consist of freshwater-fishes from tropical
+America and Asia, which, however, enter also brackish water; and of a
+truly marine genus from Australia.
+
+   AMPHIPNOUS.--Vent in the posterior half of the body, which is
+   covered with minute scales longitudinally arranged.
+
+A common fish (_A. cuchia_) in Bengal, remarkable for its singular
+respiratory apparatus. It has only three branchial arches, with
+rudimentary branchial laminæ, and with very narrow slits between the
+arches. To supplement this insufficient respiratory apparatus, a
+lung-like sac is developed on each side of the body behind the head,
+opening between the hyoid and first branchial arch. The interior of the
+sac is abundantly provided with blood-vessels, the arterial coming from
+the branchial arteries, whilst those issuing from it unite to form the
+aorta. _A. cuchia_ approaches the Eels in having the humeral arch not
+attached to the skull.
+
+   MONOPTERUS.--Vent in the posterior half of the body, which
+   is naked. Three branchial arches with rudimentary gills, but
+   without breathing sac.
+
+One species (_M. javanicus_), which is extremely common in the East
+Indian Archipelago and in the eastern parts of the Continent. Upwards
+of three feet long.
+
+   SYMBRANCHUS.--Vent in the posterior half of the body, which is
+   naked. Four branchial arches with well developed gills.
+
+Three species, of which one (_S. marmoratus_) is extremely common in
+tropical America, and the other (_S. bengalensis_) not less so in the
+East Indies.
+
+   CHILOBRANCHUS.--Vent in the anterior half of the length of
+   the body, which is naked. Vertical fins reduced to a simple
+   cutaneous fold, without rays.
+
+A small fish (_Ch. dorsalis_) from North Western Australia and Tasmania.
+
+
+                    THIRTY-FIRST FAMILY--MURÆNIDÆ.
+
+_Body elongate, cylindrical or “band-shaped, naked or with
+rudimentary scales. Vent situated at a great distance from the head.
+Ventral fins none. Vertical fins, if present, confluent, or separated
+by the projecting tip of the tail. Sides of the upper jaw formed by the
+tooth-bearing maxillaries, the fore part by the intermaxillary, which
+is more or less coalescent with the vomer and ethmoid. Humeral arch not
+attached to the skull. Stomach with a blind sac; no pyloric appendages.
+Organs of reproduction without efferent ducts._
+
+The “Eels” are spread over almost all fresh waters and seas of the
+temperate and tropical zones; some descend to the greatest depths
+of the oceans. The young of some have a limited pelagic existence.
+(_Leptocephali_, see p. 179.) At Monte Bolca fossil remains are very
+numerous, belonging to recent genera, _Anguilla_, _Sphagebranchus_, and
+_Ophichthys_; even larval Leptocephales have been preserved. _Anguilla_
+has been found also in the chalk of Aix and Oeningen.
+
+In the majority of the species the branchial openings in the pharynx
+are wide slits (_Murænidæ platyschistæ_); in others, the true Murænæ,
+(_Murænidæ engyschistæ_) they are narrow.
+
+   NEMICHTHYS.--Exceedingly elongate, band-shaped; tail tapering
+   into a point. Vent approximate to the pectorals, but the
+   abdominal cavity extending far behind the vent. Jaws produced
+   into a long slender bill, the upper part being formed by the
+   vomer and intermaxillaries. The inner surface of the bill
+   covered with small tooth-like asperities. Eye large. The
+   nostrils of each side are close together, in a hollow before the
+   eye. Gill-openings wide, nearly confluent. Pectoral and vertical
+   fins well developed.
+
+This very singular type is a deep-sea form, occurring at depths of from
+500 to 2500 fathoms. The two species known have hitherto been found in
+the Atlantic only.
+
+   CYEMA.--This genus combines the form of the snout of
+   _Nemichthys_, with the soft and shorter body of a
+   _Leptocephalus_; but the gill-openings are very narrow and close
+   together on the abdominal surface. Vent in about the middle of
+   the length of the body; vertical fins well developed, confined
+   to, and surrounding, the tail. Pectoral fins well developed. Eye
+   very small.
+
+Known from two specimens only, 4½ inches long, dredged in depths of
+1500 and 1800 fathoms in the Pacific and Antarctic Oceans.
+
+   SACCOPHARYNX.--Deep-sea Congers, with the muscular system
+   very feebly developed, with the bones very thin, soft, and
+   wanting in inorganic matter. Head and gape enormous. Snout
+   very short, pointed, flexible, like an appendage overlapping
+   the gape. Maxillary and mandibulary bones very thin, slender,
+   arched, armed with one or two series of long, slender, curved,
+   widely set teeth, their points being directed inwards; palate
+   toothless. Gill-openings wide, at some distance from the head,
+   at the lower part of the sides; gills very narrow, free, and
+   exposed. Trunk of moderate length. Stomach distensible in
+   an extraordinary degree. Vent at the end of the trunk. Tail
+   band-like, exceedingly long, tapering in a very fine filament.
+   Pectoral small, present. Dorsal and anal fins rudimentary.
+
+This is another extraordinary form of Deep-sea Eels; the muscular
+system, except on the head, is very feebly developed; the bones are as
+thin, soft, and wanting in inorganic matter, as in the _Trachypteridæ_.
+This fish is known from three specimens only, which have been found
+floating on the surface of the North Atlantic, with their stomachs much
+distended, having swallowed some other fish, the weight of which many
+times exceeded that of their destroyer. It attains to the length of
+several feet.
+
+   SYNAPHOBRANCHUS.--Gill-openings ventral, united into a
+   longitudinal slit between the pectoral fins, separate
+   internally. Pectoral and vertical fins well developed. Nostrils
+   lateral, the anterior subtubular, the posterior round, before
+   the lower half of the eye. Cleft of the mouth very wide; teeth
+   small; body scaly. Stomach very distensible.
+
+Deep-sea Congers, with well-developed muscular system, spread over
+all oceans, and occurring in depths of from 345 to 2000 fathoms. Four
+species are known. Probably attaining to the same length as the Conger.
+
+   ANGUILLA.--Small scales imbedded in the skin. Upper jaw not
+   projecting beyond the lower. Teeth small, forming bands.
+   Gill-openings narrow, at the base of the pectoral fins. The
+   dorsal fin commences at a considerable distance from the occiput.
+
+Some twenty-five species of “Eels” are known from the freshwaters and
+coasts of the temperate and tropical zones; none have been found in
+South America or the west coast of North America and West Africa.
+The following are the most noteworthy:--The common European species
+(_A. anguilla_) is spread over Europe to 64° 30´ lat. N., and all
+round the Mediterranean area, but is not found either in the Danube
+or in the Black and Caspian Seas; it extends across the Atlantic to
+North America. The form of the snout varies much, and some naturalists
+have believed that specimens with a broad and obtuse snout were
+specifically distinct from those with pointed snout. However, every
+degree of breadth of the snout may be observed; and a much safer
+way of recognizing this species, and distinguishing it from other
+European Eels, is the forward position of the dorsal fin; the distance
+between the commencement of the dorsal and anal fins being as long as,
+or somewhat longer than, the head. Eels grow generally to a length
+of about three feet, but the capture of much larger examples is on
+record. Their mode of propagation is still unknown. So much only is
+certain that they do not spawn in fresh water, that many full-grown
+individuals, but not all, descend rivers during the winter months, and
+that some of them at least must spawn in brackish water or in deep
+water in the sea; for in the course of the summer young individuals
+from three to five inches long ascend rivers in incredible numbers,
+overcoming all obstacles, ascending vertical walls or floodgates,
+entering every larger and smaller tributary, and making their way
+even over terra firma to waters shut off from all communication
+with rivers. Such immigrations have been long known by the name of
+“_Eel-fairs_.” The majority of the Eels which migrate to the sea
+appear to return to fresh water, but not in a body, but irregularly,
+and throughout the warmer part of the year. No naturalist has ever
+observed these fishes in the act of spawning, or found mature ova; and
+the organs of reproduction of individuals caught in fresh water are
+so little developed and so much alike, that the female organ can be
+distinguished from the male only with the aid of a microscope.
+
+The second species found in Great Britain, on the coasts of Europe
+generally, in China, New Zealand, and the West Indies, is (_A.
+latirostris_) the “Grig” or “Glut,” which prefers the neighbourhood of
+the sea to distant inland-waters, and in which the dorsal fin begins
+farther backwards, the distance between the commencement of the dorsal
+and anal fins being shorter than the head; its snout seems to be always
+broad. On the American side of the Atlantic other species, beside _A.
+anguilla_ are found in abundance: _A. bostoniensis_, _A. texana_.
+The largest Eels occur in lakes of the islands of the Indo-Pacific,
+and they play a conspicuous part in the mythology of the South-Sea
+Islanders and Maories; individuals of from eight to ten feet in length
+have been seen, and referred to several species, as _A. mauritiana_,
+_fidjiensis_, _obscura_, _aneitensis_, etc.
+
+   CONGER.--Scaleless. Cleft of the mouth wide, extending at least
+   to below the middle of the eye. Maxillary and mandibulary
+   teeth arranged in series, one of which contains teeth of equal
+   size, and so closely set as to form a cutting edge. No canine
+   teeth. Vomerine band of teeth short. Pectoral and vertical fins
+   well developed, the dorsal commencing behind the root of the
+   pectoral. Gill-openings large, approximate to the abdomen. The
+   posterior nostril opposite to the upper or middle part of the
+   orbit, the anterior in a tube. Eyes well developed.
+
+The “Congers” are marine Eels; the best known species (_C. conger_)
+seems to be almost cosmopolitan, and is plentiful all round Europe, at
+St. Helena, in Japan, and Tasmania. It attains to a length of eight
+feet, and thrives and grows rapidly even in confinement, which is
+not the case with the freshwater Eel. Three other species are known,
+of which _C. marginatus_ from the Indian Ocean, is the most common.
+_Leptocephalus morrisii_ is an abnormal larval condition of the Conger.
+
+Genera allied to _Conger_ are _Poeciloconger_, _Congromurcæna_,
+_Uroconger_, and _Heteroconger_.
+
+   MURÆNESOX.--Scaleless. Snout produced. Jaws with several series
+   of small closely set teeth, anteriorly with canines; vomer with
+   several long series of teeth, the middle of which is formed
+   by large conical or compressed teeth. Gill-openings wide,
+   approximate to the abdomen. Pectoral and vertical fins well
+   developed, the dorsal beginning above the gill-opening. Two
+   pairs of nostrils, the posterior opposite to the upper part or
+   middle of the eye.
+
+Four species from tropical seas, _M. cinereus_ being very common in the
+Indian Ocean, and attaining to a length of six feet.
+
+   NETTASTOMA.--Scaleless. Snout much produced, depressed. Jaws
+   and vomer with bands of card-like teeth, those along the median
+   line of the vomer being somewhat the larger. Vertical fins well
+   developed; pectorals none. Gill-openings of moderate width,
+   open. Nostrils on the upper surface of the head, valvular; the
+   anterior near to the end of the snout, the posterior above the
+   anterior angle of the eye.
+
+This genus lives at some depth, the Japanese species (_N. parviceps_)
+having been obtained at 345 fathoms. _N. melanurum_ from the
+Mediterranean, seems to inhabit a similar depth. _Hyoprorus_ is its
+Leptocephalid form.
+
+Genera allied to _Murcænesox_ are _Saurenchelys_, _Oxyconger_,
+_Hoplunnis_, and _Neoconger_; in all these the nostrils have a
+superior or lateral position. In other genera the nostrils perforate
+the upper lip, as in _Myrus_, _Myrophis_, _Paramyrus_, _Chilorhinus_,
+_Murænichthys_, and _Ophichthys_, the last genus deserving of
+particular mention on account of its great range and common occurrence.
+
+   OPHICHTHYS.--Nostrils labial; extremity of the tail free, not
+   surrounded by a fin.
+
+More than eighty species are known, many of which are abundant on the
+coasts of the tropical and sub-tropical zones. They do not attain to
+a large size, but many must be extremely voracious and destructive to
+other fishes, if we draw an inference from the formidable dentition
+with which their jaws and palate is armed. Other species have much
+more feeble, and some even obtuse teeth, better adapted for seizing
+Crustaceans than vigorous and slippery fishes. Some have rudimentary
+pectoral fins or lack them altogether. Many are highly ornamented with
+bands or spots, the coloration being apparently very constant in the
+several species.
+
+  [Illustration: Fig. 303.--Ophichthys crocodilinus, from the
+  Indo-Pacific.]
+
+   MORINGUA.--Body scaleless, cylindrical, with the trunk much
+   longer than the tail. Pectorals none or small; vertical fins
+   but little developed, limited to the tail. Posterior nostrils
+   in front of the small eye. Cleft of the mouth narrow; teeth
+   uniserial. Heart placed far behind the branchiæ. Gill-openings
+   rather narrow, inferior.
+
+Six species from freshwaters, brackish water, and the coasts of India
+to the Fiji Islands.
+
+   MURÆNA.--Scaleless. Teeth well developed. Gill-openings and
+   clefts between the branchial arches narrow. Pectoral fins none;
+   dorsal and anal fins well developed. Two nostrils on each side
+   of the upper surface of the snout; the posterior a narrow round
+   foramen, with or without tube; the anterior in a tube.
+
+  [Illustration: Fig. 304.--Head of a Muræna.]
+
+  [Illustration: Fig. 305.--Muræna pavonina, from Southern Seas.]
+
+The Murænas are as abundantly represented in the tropical and
+sub-tropical zones, and have nearly the same range, as _Ophichthys_.
+The number of species known exceeds eighty. The majority are armed
+with formidable pointed teeth, well suited for seizing other fish on
+which they prey. Large specimens thus armed readily attack persons in
+and out of the water; and as some species attain a length of some six
+or eight feet, they are justly feared by fishermen. The minority of
+species have obtuse and molar-like teeth, their food consisting chiefly
+of Crustaceans and other hard-shelled animals. Most of the Murænas
+are beautifully coloured and spotted, some in a regular and constant
+manner, whilst in others the pattern varies in a most irregular
+fashion: they have quite the appearance of snakes. The Muræna of
+the Ancient Romans is _Muræna helena_, which is not confined to the
+Mediterranean, but also found in the Indian Ocean and on the coast of
+Australia. Its skin is of a rich brown, beautifully marked with large
+yellowish spots, each of which contains smaller brown spots.
+
+  [Illustration: Fig. 306.--Muræna picta, from the Indo-Pacific.]
+
+_Gymnomuræna_ differs from _Muræna_ in having the fins reduced to a
+short rudiment near the end of the tail. Six species are known growing
+to a length of eight feet.
+
+  [Illustration: Fig. 307.--Gymnomuræna vittata, from Cuba.]
+
+_Myroconger_ and _Enchelycore_ belong to the same sub-family as
+_Muræna_, but the former is provided with pectoral fins, and in the
+latter the posterior nostril is a long slit, and not round as in the
+other genera.
+
+
+                      FIFTH ORDER--LOPHOBRANCHII.
+
+_The gills are not laminated, but composed of small rounded lobes
+attached to the branchial arches. Gill-cover reduced to a large simple
+plate. Air-bladder simple, without pneumatic duct. A dermal skeleton
+composed of numerous pieces arranged in segments, replaces more or less
+soft integuments. Muscular system not much developed. Snout prolonged.
+Mouth terminal, small, toothless, formed as in Acanthopterygians._
+
+  [Illustration: Fig. 308.--Gills of Hippocampus abdominalis.]
+
+
+                     FIRST FAMILY--SOLENOSTOMIDÆ.
+
+_Gill-openings wide. Two dorsal fins, the rays of the anterior not
+articulated. All the other fins well developed._
+
+One living genus only is known, which was preceded in the tertiary
+epoch by _Solenorhynchus_ (Monte Postale).
+
+   SOLENOSTOMA.--Snout produced into a long tube. Body compressed,
+   with very short tail. All parts covered with thin skin, below
+   which there is a dermal skeleton formed by large star-like
+   ossifications. The soft dorsal and anal fins on elevated
+   bases; caudal fin long. Ventral fins inserted opposite to the
+   anterior dorsal, close together, seven-rayed; they are free in
+   the male, but in the female their inner side coalesces with the
+   integuments of the body, a large pouch for the reception of
+   the eggs being formed thereby. Air-bladder and pseudobranchiæ
+   absent. Branchiostegals four, very thin. Intestinal tract very
+   simple, with a stomachic dilatation, without pyloric appendages.
+   Ova very small.
+
+The dermal skeleton of this singular type is formed by star-like
+ossifications, four in each horizontal and vertical series on the side
+of the fore part of the trunk; each consists of four or three radiating
+branches by which it joins the neighbouring bones; on the hind part
+of the trunk and tail the series are diminished to two. The dorsal
+and abdominal profiles in front of the fins are protected by similar
+bones. The vertebral column is composed of eighteen abdominal and
+fifteen caudal vertebræ, the vertebræ gradually decreasing in length
+backwards, so that the shortness of the tail is caused not only by
+the smaller number of vertebræ, but also by their much lesser length.
+Neural and hæmal spines are developed. The pelvis consists of two pairs
+of cartilaginous laminæ, the convex margin of the anterior fitting
+into an angle of a dermal bone which separates the pelvis from the
+well-ossified humeral arch.
+
+The singular provision for the retention and protection of the eggs has
+been described above (p. 162, figs. 73 and 74), and we have only to
+repeat here that it is the female which takes care of the progeny, and
+not the male as in the following family. Two or three small species are
+known from the Indian Ocean; they are beautifully marked, especially
+the male, which also appears to be of smaller size in this genus than
+the female.
+
+
+                      SECOND FAMILY--SYNGNATHIDÆ.
+
+_Gill-openings reduced to a very small opening near the upper
+posterior angle of the gill-cover. One soft dorsal fin; no ventrals,
+and, sometimes, one or more of the other fins are also absent._
+
+Small marine fishes, which are abundant on such parts of the coasts
+of the tropical and temperate zones as offer by their vegetation
+shelter to these defenceless creatures. They are bad swimmers (the
+dorsal fin being the principal organ of locomotion), and frequently
+and resistlessly carried by currents into the open ocean or to distant
+coasts. All enter brackish water, some fresh water. The strata of Monte
+Bolca and Licata (Sicily) have, yielded evidence of their existence in
+the tertiary epochs; beside species of _Siphonostoma_ and _Syngnathus_
+(_Pseudosyngnathus_), remains of an extinct genus, _Calamostoma_,
+allied to _Hippocampus_, but with a distinct caudal fin, have been
+found. On their propagation see p. 163, Fig. 76.
+
+   A. SYNGNATHINA.--The tail is not prehensile, and generally
+   provided with a caudal fin.--_Pipe-Fishes._
+
+   SIPHONOSTOMA.--Body with distinct ridges, the upper caudal
+   ridge continuous with the lateral line, but not with the dorsal
+   ridge of the trunk. Pectoral and caudal fins well developed;
+   dorsal fin of moderate length, opposite to the vent. Humeral
+   bones movable, not united into a “breast-ring.” Males with an
+   egg-pouch on the tail, the eggs being covered by cutaneous folds.
+
+Two species, of which _S. typhle_ is common on the British, and
+generally distributed on the European coasts.
+
+   SYNGNATHUS.--Body with the ridges more or less distinct, the
+   dorsal ridge of the trunk not being continuous with that of the
+   tail. Pectoral fins well developed; caudal present. Dorsal fin
+   opposite or near to the vent. Humeral bones firmly united into
+   the breast-ring. Egg-pouch as in _Siphonostoma_.
+
+The distribution of this genus nearly coincides with that of the
+family, some fifty species being known. _S. acus_, the great Pipe-fish
+(see Fig. 75, p. 163), is one of the most common European fishes,
+extending across the Atlantic and southwards to the Cape of Good
+Hope; it attains a length of 18 inches. Another very common species,
+frequently met at sea, and spread over nearly all the tropical and
+sub-tropical seas, is _S. pelagicus_, agreeably marked with alternate
+brown and silvery cross-bars.
+
+   DORYICHTHYS.--Body with the ridges well developed. Pectoral and
+   caudal fins present. Dorsal fin long or of moderate length,
+   opposite to the vent. Humeral bones firmly united. Males with
+   the lower ridges of the abdomen dilated, the dilated parts
+   forming a broad groove for the reception of the ova.
+
+In these Pipe-fishes the ova are not received in a completely closed
+pouch, but glued on to the surface of the abdomen. Twenty species from
+tropical seas.
+
+   NEROPHIS.--Body smooth, rounded, with scarcely any of the ridges
+   distinct. Pectoral fin none, caudal absent or rudimentary, the
+   tail tapering into a point. Dorsal fin of moderate length,
+   opposite to the vent. The ova are attached to the soft
+   integument of the abdomen of the male, and are not covered by
+   lateral folds of the skin.
+
+Seven species from the European seas and the Atlantic. _N. æquoreus_
+(Ocean Pipe-fish), _N. ophidion_ (Straight-nosed Pipe-fish), and _N.
+lumbriciformis_ (Little Pipe-fish), are common on the British coasts.
+
+   PROTOCAMPUS.--The whole dermal skeleton is covered with skin.
+   A broad cutaneous fold runs along the back in front and behind
+   the dorsal; a similar fold along the abdomen. Pectoral fin none;
+   caudal very small.
+
+The single species of this remarkable genus, _P. hymenolomus_, occurs
+in the Falkland Islands. It may be regarded as an embryonal form of
+_Nerophis_, the median skin-folds being evidently remains of the fringe
+which surrounds the body of the embryo.
+
+The other genera belonging to this group are, _Icthyocampus_,
+_Nannocampus_, _Urocampus_, _Leptoichthys_, _Coelonotus_, and
+_Stigmatophora_.
+
+   HIPPOCAMPINA.--The tail is prehensile, and invariably without
+   caudal fin.--_Sea-horses._
+
+   GASTROTOKEUS.--Body depressed, the lateral line running along
+   the margin of the abdomen. Shields smooth. Tail shorter than the
+   body. Pectoral fins. No pouch is developed for the ova, which
+   are imbedded in the soft integument of the abdomen of the male.
+
+_Gastrotokeus biaculeatus_, very common in the Indian Ocean to the
+coasts of Australia.
+
+   SOLENOGNATHUS.--Body compressed, deeper than broad. Shields
+   hard, rugose, with round or oval interannular plates; and
+   without elongate processes. Tail shorter than the body. Pectoral
+   fins.
+
+Three species, from the Chinese and Australian Seas; they are the
+largest of Lophobranchs, _S. hardwickii_, attaining to a length of
+nearly two feet.
+
+  [Illustration: Fig. 309.--Phyllopteryx eques.]
+
+   PHYLLOPTERYX.--Body compressed, or as broad as deep. Shields
+   smooth, but some or all of them are provided with prominent
+   spines or processes on the edges of the body; some of the
+   processes with cutaneous filaments. A pair of spines on the
+   upper side of the snout and above the orbit. Tail about as
+   long as the body. Pectoral fins. The ova are imbedded in soft
+   membrane on the lower side of the tail, without a pouch being
+   developed.
+
+Three species from the coasts of Australia. The protective resemblances
+with which many Lophobranchs are furnished, attain to the highest
+degree of development in the fishes of this genus. Not only their
+colour closely assimilates that of the particular kind of seaweed which
+they frequent, but the appendages of their spines seem to be merely
+part of the fucus to which they are attached. They attain a length of
+12 inches.
+
+   HIPPOCAMPUS.--Trunk compressed, more or less elevated. Shields
+   with more or less prominent tubercles or spines. Occiput
+   compressed into a crest, terminating at its supero-posterior
+   corner in a prominent knob (coronet). Pectoral fins. The males
+   carry the eggs in a sac at the base of the tail, opening near
+   the vent.
+
+A singular resemblance of the head and fore part of the body to that
+of a horse, has given to these fishes the name of “Sea-horses.” They
+are abundant between and near the tropics, becoming scarcer in higher
+latitudes. Some twenty species are known, some of which have a wide
+geographical range, as they are often carried to great distances with
+floating objects to which they happen to be attached.--_Acentronura_ is
+a genus closely allied to _Hippocampus_.
+
+
+                      SIXTH ORDER--PLECTOGNATHI.
+
+_Teleosteous fishes with rough scales, or with ossifications of the
+cutis in the form of scutes or spines; skin sometimes entirely naked.
+Skeleton incompletely ossified, with the vertebræ in small number.
+Gills pectinate; a narrow gill-opening in front of the pectoral fins.
+Mouth narrow; the bones of the upper jaw generally firmly united. A
+soft dorsal fin, belonging to the caudal portion of the vertebral
+column, opposite to the anal; sometimes elements of a spinous dorsal
+besides. Ventral fin none, or reduced to spines. Air-bladder without
+pneumatic duct._
+
+
+                      FIRST FAMILY--SCLERODERMI.
+
+_Snout somewhat produced; jaws armed with distinct teeth in small
+number. Skin with scutes or rough. The elements of a spinous dorsal and
+ventral fins generally present._
+
+Marine fishes of moderate or small size, very common in the tropical
+zone, but scarcer in higher latitudes. They have been found in three
+localities of tertiary strata, viz., at Monte Bolca, where a species of
+_Ostracion_ occurs, and in the Schists of Glaris, from which two genera
+have been described, _Acanthoderma_ and _Acanthopleurus_, closely
+allied to _Balistes_ and _Triacanthus_. _Glyptocephalus_ from the Isle
+of Sheppey has the skull of a Balistes, but its body is covered with
+tubercles arranged in regular series. The Scleroderms may be divided
+into three very natural groups:--
+
+   A. TRIACANTHINA.--The skin is covered with small, rough,
+   scale-like scutes. A spinous dorsal fin with from four to six
+   spines. A pair of strong, movable ventral spines, joined to the
+   pelvic bone.
+
+To this group belong the genera _Triacanthodes_, _Hollardia_, and
+_Triacanthus_, represented by five species, of which _Triacanthus
+brevirostris_ from the Indian Ocean is the most common.
+
+   B. BALISTINA.--Body compressed, covered with movable scutes or
+   rough. Spinous dorsal reduced to one, two, or three spines.
+   Ventral fins reduced to a single pelvic prominence, or entirely
+   absent.
+
+To this group belong the genera _Balistes_, _Monacanthus_, and
+_Anacanthus_, the last genus being distinguished by a barbel at the
+lower jaw.
+
+  [Illustration: Fig. 310.--Balistes vidua.]
+
+_Balistes_, or the “File-fishes” proper, inhabit the tropical and
+sub-tropical seas; shoals of young are not rarely met with in
+mid-ocean. Some thirty species are known, many attaining a length
+exceeding two feet; but the majority are much smaller, and frequently
+beautifully and symmetrically marked. Both jaws are armed with eight
+strong incisor-like and obliquely truncated teeth, by which these
+fishes are enabled to break off pieces of corals on which they feed,
+or to chisel a hole into the hard shell of Mollusca, in order to
+extract the soft parts. They destroy an immense number of Mollusks,
+thus becoming most injurious to the pearl-fisheries. The first of their
+three dorsal spines is very strong, roughened in front like a file,
+and hollowed out behind to receive the second much smaller spine,
+which, besides, has a projection in front, at its base, fitting into
+a notch of the first. Thus these two spines can only be raised or
+depressed simultaneously, and the first cannot be forced down, unless
+the second has been previously depressed. The latter has been compared
+to a trigger, hence a second name, “Trigger-fish,” has been given to
+these fishes. Some species are armed with a series of short spines or
+tubercles on each side of the tail. Two species (_B. maculatus_ and _B.
+capriscus_), common in the Atlantic, sometimes wander to the British
+coasts.
+
+The _Monacanthus_ are similarly distributed as the _Balistes_, and
+still more abundant, some fifty species being known. Their dentition
+is very similar, but they possess one dorsal spine only, and their
+rough scales are so small as to give a velvety appearance to the skin
+(Figs. 17 and 18, p. 48). Adult males of some of the species possess a
+peculiar armature on each side of the tail, which in females is much
+less developed or entirely absent. This armature may consist either in
+simple spines arranged in rows, or in the development of the minute
+spines of the scales into long stiff bristles, so that the patch on
+each side of the tail looks like a brush.
+
+   C. OSTRACIONTINA.--The integuments of the body form a hard
+   continuous carapace, consisting of hexagonal scutes juxtaposed
+   in mosaic-fashion. A spinous dorsal and ventral fins are absent;
+   but sometimes indicated by protuberances.
+
+The “Coffer-fishes” (_Ostracion_) are too well known to require a
+lengthened description. Only the snout, the bases of the fins, and the
+hind part of the tail are covered with soft skin, so as to admit of
+free action of the muscles moving these parts. The mouth is small, the
+maxillary and intermaxillary bones coalescent, each jaw being armed
+with a single series of small slender teeth. The short dorsal fin is
+opposite to the equally short anal. The vertebral column consists of
+fourteen vertebræ only, of which the five last are extremely short,
+the anterior elongate. Ribs none. The carapaces of some species are
+three-ridged, of others four- and five-ridged, of some provided with
+long spines. Twenty-two species from tropical and sub-tropical seas are
+known.
+
+
+                      SECOND FAMILY--GYMNODONTES.
+
+_Body more or less shortened. The bones of the upper and lower
+jaw are confluent, forming a beak with a trenchant edge, without
+teeth, with or without median suture. A soft dorsal, caudal and anal
+are developed, approximate. No spinous dorsal. Pectoral fins; no
+ventrals._
+
+Marine fishes of moderate or small size from tropical and sub-tropical
+seas. A few species live in fresh water. Fossil remains of
+_Diodon_ are not scarce at Monte Bolca and Licata; a distinct
+genus, _Enneodon_, has been described from Monte Postale. The
+Gymnodonts may be divided into three groups:
+
+   A. TRIODONTINA.--Tail rather long, with a separate caudal fin.
+   Abdomen dilatable into a very large, compressed, pendent sac,
+   the lower part of which is merely a flap of skin, into which the
+   air does not penetrate, the sac being capable of being expanded
+   by the very long pelvic bone. The upper jaw divided by a median
+   suture, the lower simple.
+
+A single genus and species (_Triodon bursarius_) from the Indian
+Ocean.
+
+   B. TETRODONTINA.--Tail and caudal fin distinct. Part of the
+   œsophagus much distensible, and capable of being filled with
+   air. No pelvic bone.
+
+“Globe-fishes” have a short, thick, cylindrical body, with well
+developed fins. It is covered with thick scaleless skin, in which,
+however, spines are imbedded of various sizes. The spines are very
+small, and but partially distributed over the body in some species,
+whilst in others they are very large, and occupy equally every part
+of the body. These fishes have the power of inflating their body by
+filling their distensible œsophagus with air, and thus assume a more or
+less globular form. The skin is, then, stretched to its utmost extent,
+and the spines protrude and form a more or less formidable defensive
+armour, as in a hedgehog; therefore they are frequently called
+“Sea-hedgehogs.” A fish thus blown out turns over and floats belly
+upwards, driving before the wind and waves. However, it is probable
+that the spines are a protection not only when the fish is on the
+surface and able to take in air, but also when it is under water. Some
+Diodonts, at any rate, are able to erect the spines about the head by
+means of cutaneous muscles; and, perhaps, all fill their stomach with
+water instead of air, for the same purpose and with the same effect. In
+some Diodonts the spines are fixed, erect, not movable. The Gymnodonts
+generally, when taken, produce a sound, doubtless by the expulsion
+of air from the œsophagus. Their vertebral column consists of a small
+number of vertebræ, from 20 to 29, and their spinal chord is extremely
+short. All these fishes have a bad reputation, and they are never
+eaten; indeed, some of them are highly poisonous, and have caused long
+continued illness and death. Singularly, the poisonous properties of
+these fishes vary much as regards intensity, only certain individuals
+of a species, or individuals from a certain locality, or caught at a
+certain time of the year, being dangerous. Therefore it is probable
+that they acquire their poisonous quality from their food, which
+consists in corals and hard-shelled Mollusks and Crustaceans. Their
+sharp beaks, with broad masticating posterior surface, are admirably
+adapted for breaking off branchlets of coral-stocks, and for crushing
+hard substances.
+
+  [Illustration: Fig. 311.--Jaws of Tetrodon.]
+
+  [Illustration: Fig. 312.--Tetrodon margaritatus.]
+
+   TETRODON (including _Xenopterus_).--Both the upper and lower
+   jaws are divided into two by a mesial suture.
+
+Extremely numerous in tropical and sub-tropical zones, more than
+sixty species being known. In some of the species the dermal
+spines are extremely small, and may be absent altogether. Many are
+highly ornamented with spots or bands. A few species live in large
+rivers--thus _T. psittacus_ from Brazil; _T. fahaka_, a fish well
+known to travellers on the Nile, and likewise abundant in West African
+rivers; _T. fluvi__atilis_ from brackish water and rivers of the East
+Indies. The species figured is one of the smallest, about six inches
+long, and common in the Indo-Pacific.
+
+   DIODON.--Jaws without mesial suture, so that there is only one
+   undivided dental plate above and one below.
+
+In these fishes, as well as in some closely allied genera, the dermal
+spines are much more developed than in the Tetrodonts; in some the
+spines are erectile, as in _Diodon_, _Atopomycterus_, _Trichodiodon_,
+and _Trichocyclus_; in others they are stiff and immovable, as in
+_Chilomycterus_ and _Dicotylichthys_. Seventeen species are known, of
+which _Diodon hystrix_ is the most common as it is the largest, growing
+to a length of two feet. It is spread over the Tropical Atlantic as
+well as Indo-Pacific, as is also a smaller, but almost equally common
+species, _Diodon maculatus_.
+
+  [Illustration: Fig. 313.--Diodon maculatus.]
+
+  [Illustration: Fig. 314.--Diodon maculatus, inflated.]
+
+   C. MOLINA.--Body compressed, very short; tail extremely short,
+   truncate. Vertical fins confluent. No pelvic bone.
+
+The “Sun-fishes” (_Orthagoriscus_) are pelagic fishes, found in every
+part of the oceans within the tropical and temperate zones. The
+singular shape of their body and the remarkable changes which they
+undergo with age, have been noticed above (p. 175, Figs. 93, 94).
+Their jaws are undivided in the middle, comparatively feeble, but well
+adapted for masticating their food, which consists of small pelagic
+Crustaceans. Two species are known. The common Sun-fish, _O. mola_,
+which attains to a very large size, measuring seven or eight feet, and
+weighing as many hundredweights. It has a rough, minutely granulated
+skin. It frequently approaches the southern coasts of England and the
+coasts of Ireland, and is seen basking in calm weather on the surface.
+The second species, _O. truncatus_, is distinguished by its smooth,
+tessellated skin, and one of the scarcest fishes in collections. The
+shortness of the vertebral column of the Sun-fishes, in which the
+number of caudal vertebra is reduced to seven, the total number being
+seventeen, and the still more reduced length of the spinal chord have
+been noticed above (p. 96).
+
+
+                    THIRD SUB-CLASS--CYCLOSTOMATA.
+
+_Skeleton cartilaginous and notochordal, without ribs and without
+real jaws. Skull not separate from the vertebral column. No limbs.
+Gills in the form of fixed sacs, without branchial arches, six or seven
+in number on each side. One nasal aperture only. Heart without bulbus
+arteriosus. Mouth anterior, surrounded by a circular or subcircular
+lip, suctorial. Alimentary canal straight, simple, without coecal
+appendages, pancreas or spleen. Generative outlet peritoneal. Vertical
+fins rayed._
+
+The Cyclostomes are most probably a very ancient type. Unfortunately
+the organs of these creatures are too soft to be preserved, with the
+exception of the horny denticles with which the mouth of some of them
+is armed. And, indeed, dental plates, which are very similar to those
+of _Myxine_, are not uncommon in certain strata of Devonian and
+Silurian age (see p. 193). The fishes belonging to this sub-class may
+be divided into two families--
+
+
+                     FIRST FAMILY--PETROMYZONTIDÆ.
+
+_Body eel-shaped, naked. Subject to a metamorphosis; in the perfect
+stage with a suctorial mouth armed with teeth, simple or multicuspid,
+horny, sitting on a soft papilla. Maxillary, mandibulary, lingual, and
+suctorial teeth may be distinguished. Eyes present (in mature animals).
+External nasal aperture in the middle of the upper side of the head.
+The nasal duct terminates without perforating the palate. Seven
+branchial sacs and apertures on each side behind the head; the inner
+branchial ducts terminate in a separate common tube. Intestine with a
+spiral valve. Eggs small. The larvæ without teeth, and with a single
+continuous vertical fin._
+
+“Lampreys” are found in the rivers and on the coasts of the temperate
+regions of the northern and southern hemispheres. Their habits are but
+incompletely known, but so much is certain that at least some of them
+ascend rivers periodically, for the purpose of spawning, and that the
+young pass several years in rivers, whilst they undergo a metamorphosis
+(see p. 170). They feed on other fishes, to which they suck themselves
+fast, scraping off the flesh with their teeth. Whilst thus engaged they
+are carried about by their victim; Salmon have been captured in the
+middle course of the Rhine with the Marine Lamprey attached to them.
+
+  [Illustration: Fig. 315.--Mouth of Larva of Petromyzon
+  branchialis.]
+
+  [Illustration: Fig. 316.--Mouth of Petromyzon fluviatilis.
+  _mx_, Maxillary tooth; _md_, Mandibulary tooth;
+  _l_, Lingual tooth; _s_, Suctorial teeth.]
+
+   PETROMYZON.--Dorsal fins two, the posterior continuous with the
+   caudal. The maxillary dentition consists of two teeth placed
+   close together, or of a transverse bicuspid ridge; lingual teeth
+   serrated.
+
+The Lampreys belonging to this genus are found in the northern
+hemisphere only; the British species are the Sea-Lamprey (_P.
+marinus_), exceeding a length of three feet, and not uncommon on the
+European and North American coasts; the River-Lamprey or Lampern (_P.
+fluviatilis_), ascending in large numbers the rivers of Europe, North
+America, and Japan, and scarcely attaining a length of two feet; the
+“Pride” or “Sand-Piper” or Small Lampern (_P. branchialis_), scarcely
+twelve inches long, the larva of which has been long known under the
+name of _Ammocoetes_.
+
+_Ichthyomyzon_ from the western coasts of North America is said to have
+a tricuspid maxillary tooth.
+
+   MORDACIA.--Dorsal fins two, the posterior continuous with the
+   caudal. The maxillary dentition consists of two triangular
+   groups, each with three conical acute cusps; two pairs of
+   serrated lingual teeth.
+
+  [Illustration: Fig. 317.--Mouth of Mordacia mordax, closed and
+  opened.]
+
+A Lamprey _(M. mordax_) from the coasts of Chile and Tasmania. This
+fish seems to be provided sometimes with a gular sac, like the
+following.[47]
+
+  [Illustration: Fig. 318.--Mordacia mordax.]
+
+   GEOTRIA.--Dorsal fins two, the posterior separate from the
+   caudal. Maxillary lamina with four sharp flat lobes; a pair of
+   long pointed lingual teeth.
+
+Two species, one from Chile and one from South Australia. They grow
+to a length of two feet, and in some specimens the skin of the throat
+is much expanded, forming a large pouch. Its physiological function
+is not known. The cavity is in the subcutaneous cellular tissue, and
+does not communicate with the buccal or branchial cavities. Probably
+it is developed with age, and absent in young individuals. In all
+the localities in which these Extra-european Lampreys are found,
+_Ammocoetes_ forms occur, so that there is little doubt that they
+undergo a similar metamorphosis as _P. branchialis_.
+
+
+                       SECOND FAMILY--MYXINIDÆ.
+
+_Body eel-shaped, naked. The single nasal aperture is above the
+mouth, quite at the extremity of the head, which is provided with four
+pairs of barbels. Mouth without lips. Nasal duct without cartilaginous
+rings, penetrating the palate. One median tooth on the palate, and
+two comb-like series of teeth on the tongue_ (see Fig. 101).
+_Branchial apertures at a great distance from the head; the inner
+branchial ducts lead into the œsophagus. A series of mucous sacs along
+each side of the abdomen. Intestine without spiral valve. Eggs large,
+with a horny case provided with threads for adhesion._
+
+  [Illustration: Fig. 319.--Ovum of Myxine glutinosa, enlarged.]
+
+The fishes of this family are known by the names of “Hag-Fish,”
+“Glutinous Hag,” or “Borer;” they are marine fishes with a similar
+distribution as the Gadidæ, being most plentiful in the higher
+latitudes of the temperate zones of the northern and southern
+hemispheres. They are frequently found buried in the abdominal cavity
+of other fishes, especially Gadoids, into which they penetrate to feed
+on their flesh. They secrete a thick glutinous slime in incredible
+quantities, and are therefore considered by fishermen a great nuisance,
+seriously damaging the fisheries and interfering with the fishing in
+localities where they abound. _Myxine_ descends to a depth of
+345 fathoms, and is generally met with in the Norwegian Fjords at 70
+fathoms, sometimes in great abundance.
+
+   MYXINE.--One external branchial aperture only on each side of
+   the abdomen, leading by six ducts to six branchial sacs.
+
+Three species from the North Atlantic, Japan, and Magelhæn’s Straits.
+
+  [Illustration: Fig. 320.--Myxine australis. A, Lower aspect
+  of head; _a_, Nasal aperture; _b_, Mouth; _g_,
+  Branchial aperture; _v_, Vent.]
+
+   BDELLOSTOMA.--Six or more external branchial apertures on each
+   side, each leading by a separate duct to a branchial sac.
+
+Two species from the South Pacific.
+
+
+                    FOURTH SUB-CLASS--LEPTOCARDII.
+
+
+_Skeleton membrano-cartilaginous and notochordal, ribless. No brain.
+Pulsating sinuses in place of a heart. Blood colourless. Respiratory
+cavity confluent with the abdominal cavity; branchial clefts in great
+number, the water being expelled by an opening in front of the vent.
+Jaws none._
+
+This sub-class is represented by a single family (_Cirrostomi_)
+and by a single genus (_Branchiostoma_);[48] it is the lowest in
+the scale of fishes, and lacks so many characteristics, not only of
+this class, but of the vertebrata generally, that Hæckel, with good
+reason, separates it into a separate class, that of _Acrania_. The
+various parts of its organisation have been duly noticed in the first
+part of this work.
+
+The “Lancelet” (_Branchiostoma lanceolatum_, see Fig. 28, p. 63),
+seems to be almost cosmopolitan within the temperate and tropical
+zones. Its small size, its transparency, and the rapidity with which it
+is able to bury itself in the sand, are the causes why it escapes so
+readily observation, even at localities where it is known to be common.
+Shallow, sandy parts of the coasts seem to be the places on which it
+may be looked for. It has been found on many localities of the British,
+and generally European coasts, in North America, the West Indies,
+Brazil, Peru, Tasmania, Australia, and Borneo. It rarely exceeds
+a length of three inches. A smaller species, in which the dorsal
+fringe is distinctly higher and rayed, and in which the caudal fringe
+is absent, has been described under the name of _Epigionichthys
+pulchellus_; it was found in Moreton Bay.
+
+
+
+
+                               APPENDIX.
+
+           DIRECTIONS FOR COLLECTING AND PRESERVING FISHES.
+
+
+Whenever practicable fishes ought to be preserved in spirits.
+
+To insure success in preserving specimens the best and strongest
+spirits should be procured, which, if necessary, can be reduced to
+the strength required during the journey with water or weaker spirit.
+Travellers frequently have great difficulties in procuring spirits
+during their journey, and therefore it is advisable, especially during
+sea voyages, that the traveller should take a sufficient quantity
+with him. Pure spirits of wine is best. Methylated spirits may be
+recommended on account of their cheapness; however, specimens do not
+keep equally well in this fluid, and very valuable objects, or such as
+are destined for minute anatomical examination, should always be kept
+in pure spirits of wine. If the collector has exhausted his supply of
+spirits he may use arrack, cognac, or rum, provided that the fluids
+contain a sufficient quantity of alcohol. Generally speaking, spirits
+which, without being previously heated, can be ignited by a match or
+taper, may be used for the purposes of conservation. The best method
+to test the strength of the spirits is the use of a hydrometer. It
+is immersed in the fluid to be measured, and the deeper it sinks the
+stronger is the spirit. On its scale the number 0 signifies what is
+called proof spirit, the lowest degree of strength which can be used
+for the conservation of fish for any length of time. Spirits, in which
+specimens are packed permanently, should be from 40 to 60 above proof.
+If the hydrometers are made of glass they are easily broken, and
+therefore the traveller had better provide himself with three or four
+of them, their cost being very trifling. Further, the collector will
+find a small distilling apparatus very useful. By its means he is able
+not only to distil weak and deteriorated spirits or any other fluid
+containing alcohol, but also, in case of necessity, to prepare a small
+quantity of drinkable spirits.
+
+Of collecting vessels we mention first those which the collector
+requires for daily use. Most convenient are four-sided boxes made of
+zinc, 18 in. high, 12 in. broad, and 5 in. wide. They have a round
+opening at the top of 4 in. diameter, which can be closed by a strong
+cover of zinc of 5 in. diameter, the cover being screwed into a raised
+rim round the opening. In order to render the cover air-tight, an
+indiarubber ring is fixed below its margin. Each of these zinc boxes
+fits into a wooden case, the lid of which is provided with hinges and
+fastenings, and which on each side has a handle of leather or rope, so
+that the box can be easily shifted from one place to another. These
+boxes are in fact made from the pattern of the ammunition cases used
+in the British army, and extremely convenient, because a pair can be
+easily carried strapped over the shoulders of a man or across the
+back of a mule. The collector requires at least two, still better
+four or six, of these boxes. All those specimens which are received
+during the day are deposited in them, in order to allow them to be
+thoroughly penetrated by the spirit, which must be renewed from time
+to time. They remain there for some time under the supervision of the
+collector, and are left in these boxes until they are hardened and
+fit for final packing. Of course, other more simple vessels can be
+used and substituted for the collecting boxes. For instance, common
+earthenware vessels, closed by a cork or an indiarubber covering,
+provided they have a wide mouth at the top, which can be closed so
+that the spirit does not evaporate, and which permits of the specimens
+being inspected at any moment without trouble. Vessels in which the
+objects are permanently packed for the home journey are zinc boxes of
+various sizes, closely fitting into wooden cases. Too large a size
+should be avoided, because the objects themselves may suffer from the
+superimposed weight, and the risk of injury to the case increases with
+its size. It should hold no more than 18 cubic feet at most, and what,
+in accordance with the size of the specimens, has to be added in length
+should be deducted in depth or breadth. The most convenient cases,
+but not sufficient for all specimens, are boxes 2 feet in length, 1½
+foot broad, and 1 foot deep. The traveller may provide himself with
+such cases ready made, packing in them other articles which he wants
+during his journey; or he may find it more convenient to take with him
+only the zinc plates cut to the several sizes, and join them into boxes
+when they are actually required. The requisite wooden cases can be
+procured without much difficulty almost everywhere. No collector should
+be without the apparatus and materials for soldering, and he should be
+well acquainted with their use. Also a pair of scissors to cut the zinc
+plates are useful.
+
+Wooden casks are not suitable for the packing of specimens preserved
+in spirits, at least not in tropical climates. They should be used in
+cases of necessity only, or for packing of the largest examples, or for
+objects preserved in salt or brine.
+
+Very small and delicate specimens should never be packed together with
+larger ones, but separately, in small bottles.
+
+_Mode of preserving._--All fishes, with the exception of very
+large ones (broad kinds exceeding 3–4 feet in length; eel-like kinds
+more than 6 feet long), should be preserved in spirits. A deep cut
+should be made in the abdomen between the pectoral fins, another in
+front of the vent, and one or two more, according to the length of
+the fish, along the middle line of the abdomen. These cuts are made
+partly to remove the fluid and easily decomposing contents of the
+intestinal tract, partly to allow the spirit quickly to penetrate into
+the interior. In large fleshy fishes several deep incisions should
+be made with the scalpel into the thickest parts of the dorsal and
+caudal muscles, to give ready entrance to the spirits. The specimens
+are then placed in one of the provisional boxes, in order to extract,
+by means of the spirit, the water of which fishes contain a large
+quantity. After a few days (in hot climates after 24 or 48 hours) the
+specimens are transferred into a second box with stronger spirits, and
+left therein for several days. A similar third and, in hot climates
+sometimes a fourth, transfer is necessary. This depends entirely on
+the condition of the specimens. If, after ten or fourteen days of
+such treatment the specimens are firm and in good condition, they may
+be left in the spirits last used until they are finally packed. But
+if they should be soft, very flexible, and discharge a discoloured
+bloody mucus, they must be put back in spirits at least 20° over proof.
+Specimens showing distinct signs of decomposition should be thrown
+away, as they imperil all other specimens in the same vessel. Neither
+should any specimen in which decomposition has commenced when found, be
+received for the collecting boxes, unless it be of a very rare species,
+when the attempt may be made to preserve it separately in the strongest
+spirits available. The fresher the specimens to be preserved are, the
+better is the chance of keeping them in a perfect condition. Specimens
+which have lost their scales, or are otherwise much injured, should not
+be kept. Herring-like fishes, and others with deciduous scales, are
+better wrapped in thin paper or linen before being placed in spirits.
+
+The spirits used during this all-important process of preservation
+loses, of course, gradually in strength. As long as it keeps 10° under
+proof it may still be used for the first stage of preservation, but
+weaker spirits should be re-distilled; or, if the collector cannot do
+this, it should be at least filtered through powdered charcoal before
+it is mixed with stronger spirits. Many collectors are satisfied with
+removing the thick sediment collected at the bottom of the vessel,
+and use their spirits over and over again without removing from it by
+filtration the decomposing matter with which it has been impregnated,
+and which entirely neutralises the preserving property of the spirits.
+The result is generally the loss of the collection on its journey
+home. The collector can easily detect the vitiated character of his
+spirits by its bad smell. He must frequently examine his specimens; and
+attention to the rules given, with a little practice and perseverance,
+after the possible failure of the first trial, will soon insure to
+him the safety of his collected treasures. The trouble of collecting
+specimens in spirits is infinitely less than that of preserving skins
+or dry specimens of any kind.
+
+When a sufficient number of well-preserved examples have been brought
+together, they should be sent home by the earliest opportunity. Each
+specimen should be wrapped separately in a piece of linen, or at least
+soft paper; the specimens are then packed as close as herrings in the
+zinc case, so that no free space is left either at the top or on the
+sides. When the case is full, the lid is soldered on, with a round
+hole about half an inch in diameter near one of the corners. This hole
+is left in order to pour the spirit through it into the case. Care is
+taken to drive out the air which may remain between the specimens,
+and to surround them completely with spirits, until the case is quite
+full. Finally, the hole is closed by a small square lid of tin being
+soldered over it. In order to see whether the case keeps in the spirit
+perfectly, it is turned upside down and left over night. When all is
+found to be securely fastened, the zinc case is placed into the wooden
+box and ready for transport.
+
+Now and then it happens in tropical climates that collectors are unable
+to keep fishes from decomposition even in the strongest spirits without
+being able to detect the cause. In such cases a remedy will be found in
+mixing a small quantity of arsenic or sublimate with the spirits; but
+the collector ought to inform his correspondent, or the recipient of
+the collection, of this admixture having been made.
+
+In former times fishes of every kind, even those of small size, were
+preserved dry as flat skins or stuffed. Specimens thus prepared admit
+of a very superficial examination only, and therefore this method of
+conservation has been abandoned in all larger museums, and should be
+employed exceptionally only, for instance on long voyages overland,
+during which, owing to the difficulty of transport, neither spirits
+nor vessels can be carried. To make up as much as possible for the
+imperfection of such specimens, the collector ought to sketch the
+fish before it is skinned, and to colour the sketch if the species
+is ornamented with colours likely to disappear in the dry example.
+Collectors who have the requisite time and skill, ought to accompany
+their collections with drawings coloured from the living fishes; but
+at the same time it must be remembered that, valuable as such drawings
+are if accompanied by the originals from which they were made, they can
+never replace the latter, and possess a subordinate scientific value
+only.
+
+Very large fishes can be preserved as skins only; and collectors are
+strongly recommended to prepare in this manner the largest examples
+obtainable, although it will entail some trouble and expense. So
+very few large examples are exhibited in museums, the majority of the
+species being known from the young stage only, that the collector will
+find himself amply recompensed by attending to these desiderata.
+
+Scaly fishes are skinned thus: with a strong pair of scissors an
+incision is made along the median line of the abdomen from the foremost
+part of the throat, passing on one side of the base of the ventral
+and anal fins, to the root of the caudal fin, the cut being continued
+upwards to the back of the tail close to the base of the caudal. The
+skin of one side of the fish is then severed with the scalpel from the
+underlying muscles to the median line of the back; the bones which
+support the dorsal and caudal are cut through, so that these fins
+remain attached to the skin. The removal of the skin of the opposite
+side is easy. More difficult is the preparation of the head and
+scapulary region; the two halves of the scapular arch which have been
+severed from each other by the first incision are pressed towards the
+right and left, and the spine is severed behind the head, so that now
+only the head and shoulder bones remain attached to the skin. These
+parts have to be cleaned from the inside, all soft parts, the branchial
+and hyoid apparatus, and all smaller bones, being cut away with the
+scissors or scraped off with the scalpel. In many fishes, which
+are provided with a characteristic dental apparatus in the pharynx
+(Labroids, Cyprinoids), the pharyngeal bones ought to be preserved,
+and tied with a thread to the specimen. The skin being now prepared so
+far, its entire inner surface as well as the inner side of the head are
+rubbed with arsenical soap; cotton-wool, or some other soft material is
+inserted into any cavities or hollows, and finally a thin layer of the
+same material is placed between the two flaps of the skin. The specimen
+is then dried under a slight weight to keep it from shrinking.
+
+The scales of some fishes, as for instance of many kinds of herrings,
+are so delicate and deciduous that the mere handling causes them to rub
+off easily. Such fishes may be covered with thin paper (tissue-paper
+is the best), which is allowed to dry on them before skinning. There
+is no need for removing the paper before the specimen has reached its
+destination.
+
+Scaleless Fishes, as Siluroids and Sturgeons, are skinned in the same
+manner, but the skin can be rolled up over the head; such skins can
+also be preserved in spirits, in which case the traveller may save to
+himself the trouble of cleaning the head.
+
+Some Sharks are known to attain to a length of 30 feet, and some Rays
+to a width of 20 feet. The preservation of such gigantic specimens is
+much to be recommended, and although the difficulties of preserving
+fishes increase with their size, the operation is facilitated, because
+the skins of all Sharks and Rays can easily be preserved in salt and
+strong brine. Sharks are skinned much in the same way as ordinary
+fishes. In Rays an incision is made not only from the snout to the end
+of the fleshy part of the tail, but also a second across the widest
+part of the body. When the skin is removed from the fish, it is placed
+into a cask with strong brine mixed with alum, the head occupying the
+upper part of the cask; this is necessary, because this part is most
+likely to show signs of decomposition, and therefore most requires
+supervision. When the preserving fluid has become decidedly weaker from
+the extracted blood and water, it is thrown away and replaced by fresh
+brine. After a week’s or fortnight’s soaking the skin is taken out of
+the cask to allow the fluid to drain off; its inner side is covered
+with a thin layer of salt, and after being rolled up (the head being
+inside) it is packed in a cask, the bottom of which is covered with
+salt; all the interstices and the top are likewise filled with salt.
+The cask must be perfectly water-tight.
+
+Of all larger examples of which the skin is prepared, the measurements
+should be taken before skinning so as to guide the taxidermist in
+stuffing and mounting the specimens.
+
+Skeletons of large osseous fishes are as valuable as their skins. To
+preserve them it is only necessary to remove the soft parts of the
+abdominal cavity and the larger masses of muscle, the bones being left
+in their natural continuity. The remaining flesh is allowed to dry on
+the bones, and can be removed by proper maceration at home. The fins
+ought to be as carefully attended to as in a skin, and of scaly fishes
+so much of the external skin ought to be preserved as is necessary
+for the determination of the species, as otherwise it is generally
+impossible to determine more than the genus.
+
+A few remarks may be added as regards those Faunæ, which promise most
+results to the explorer, with some hints as to desirable information on
+the life and economic value of fishes.
+
+It is surprising to find how small the number is of the freshwater
+faunæ which may be regarded as well explored; the rivers of Central
+Europe, the Lower Nile, the lower and middle course of the Ganges,
+and the lower part of the Amazons are almost the only fresh waters
+in which collections made without discrimination would not reward
+the naturalist. The oceanic areas are much better known; yet almost
+everywhere novel forms can be discovered and new observations
+made. Most promising and partly quite unknown are the following
+districts:--the Arctic Ocean, all coasts south of 38° lat. S., the
+Cape of Good Hope, the Persian Gulf, the coasts of Australia (with the
+exception of Tasmania, New South Wales, and New Zealand), many of the
+little-visited groups of Pacific islands, the coasts of north-eastern
+Asia north of 35° lat. N., and the western coasts of North and South
+America.
+
+No opportunity should be lost to obtain _pelagic_ forms,
+especially the young larva-like stages of development abounding on the
+surface of the open ocean. They can be obtained without difficulty by
+means of a small narrow meshed net dragged behind the ship. The sac
+of the net is about 3 feet deep, and fastened to a strong brass-ring
+2 or 2½ feet in diameter. The net is suspended by three lines passing
+into the strong main line. It can only be used when the vessel moves
+very slowly, its speed not exceeding three knots an hour, or when a
+current passes the ship whilst at anchor. To keep the net in a vertical
+position the ring can be weighted at one point of its circumference;
+and by using heavier weights two or three drag-nets can be used
+simultaneously at different depths. This kind of fishing should be
+tried at night as well as day, as many fishes come to the surface only
+after sunset. The net must not be left long in the water, from 5 to 20
+minutes only, as delicate objects would be sure to be destroyed by the
+force of the water passing through the meshes.
+
+Objects found floating on the surface, as wood, baskets, seaweed,
+etc., deserve the attention of the travellers, as they are generally
+surrounded by small fishes or other marine animals.
+
+It is of the greatest importance to note the longitude and latitude at
+which the objects were collected in the open ocean.
+
+Fishing in great depths by means of the dredge, can be practised
+only from vessels specially fitted out for the purpose; and the
+success which attended the “Challenger,” and North American Deep-sea
+explorations, has developed Deep-sea fishing into such a speciality
+that the requisite information can be gathered better by consulting the
+reports of those expeditions than from a general account, such as could
+be given in the present work.
+
+Fishes offer an extraordinary variety with regard to their habits,
+growth, etc., so that it is impossible to enumerate in detail the
+points of interest to which the travellers should pay particular
+attention. However, the following hints may be useful.
+
+Above all, detailed accounts are desirable of all fishes forming
+important articles of trade, or capable of becoming more generally
+useful than they are at present. Therefore, deserving of special
+attention are the Sturgeons, Gadoids, Thyrsites and Chilodactylus,
+Salmonoids, Clupeoids. Wherever these fishes are found in sufficient
+abundance, new sources may be opened to trade.
+
+Exact observations should be made on the fishes the flesh of which is
+poisonous either constantly or at certain times and certain localities;
+the cause of the poisonous qualities as well as the nature of the
+poison should be ascertained. Likewise the poison of fishes provided
+with special poison-organs requires to be experimentally examined,
+especially with regard to its effects on other fishes and animals
+generally.
+
+All observations directed to sex, mode of propagation, and development,
+will have special interest: thus those relating to secondary sexual
+characters, hermaphroditism, numeric proportion of the sexes, time of
+spawning and migration, mode of spawning, construction of nests, care
+of progeny, change of form during growth, etc.
+
+If the collector is unable to preserve the largest individuals of a
+species that may come under his observation he should note at least
+their measurements. There are but few species of fishes of which the
+limit of growth is known.
+
+The history of Parasitic Fishes is almost unknown, and any
+observations with regard to their relation to their host as well as to
+their early life will prove to be valuable; nothing is known of the
+propagation of fishes even so common as Echeneis and Fierasfer, much
+less of the parasitic Freshwater Siluroids.
+
+The temperature of the blood of the larger freshwater and marine
+species should be exactly measured.
+
+Many pelagic and deep-sea fishes are provided with peculiar small
+round organs of a mother-of-pearl colour, distributed in series along
+the side of the body, especially along the abdomen. Some zoologists
+consider these organs as accessory eyes, others (and it appears to
+us with better reason) as luminous organs. They deserve an accurate
+microscopic examination made on fresh specimens; and their function
+should be ascertained from observation of the living fishes, especially
+also with regard to the question, whether or not the luminosity (if
+such be their function) is subject to the will of the fish.
+
+  [Illustration: Fig. 321.--Scopelus boops, a pelagic fish, with
+  luminous organs.]
+
+
+
+
+                                INDEX.
+
+
+    Abdominal Cavity, 123
+
+    Abdominal fins, 42
+
+    Abramis, 602
+
+    Abrostomus, 596
+
+    Acanthaphritis, 466
+
+    Acanthias, 331
+
+    Acanthicus, 576
+
+    Acanthobrama, 604
+
+    Acanthoclinus, 498
+
+    Acanthodes, 355
+
+    Acanthodini, 355
+
+    Acantholabrus, 528
+
+    Acanthonus, 547
+
+    Acanthophthalmus, 606
+
+    Acanthopsis, 606
+
+    Acanthopterygiau, 41
+
+    Acanthopterygii, 374
+
+    Acanthorhodeus, 601
+
+    Acanthurus, 438, 439
+
+    Acanus, 421
+
+    Acara, 536
+
+    Acclimatisation, 185
+
+    Acentronura, 683
+
+    Acerina, 378
+
+    Acestra, 579
+
+    Achilognathus, 601
+
+    Acipenser, 361
+
+    Acipenseridæ, 360
+
+    Acrochilus, 601
+
+    Acrochordonichthys, 567
+
+    Acrodus, 330
+
+    Acrogaster, 421
+
+    Acrognathus, 631
+
+    Acrolepis, 370
+
+    Acronuridæ, 438
+
+    Acronurus, 439
+
+    Acropoma, 395
+
+    Acyprinoid division, 218
+
+    Adipose eyelid, 113
+
+    Adipose fin, 42
+
+    Aegæonichthys, 476
+
+    Aellopos, 325
+
+    Aelurichthys, 569
+
+    Aesopia, 558
+
+    Aëtobatis, 345
+
+    African region, 227
+
+    Agassiz, 20, 31, 32
+
+    Ageniosus, 572
+
+    Agnus, 463
+
+    Agoniates, 610
+
+    Agonostoma, 504
+
+    Agonus, 480
+
+    Agrammus, 491
+
+    Agriopus, 416
+
+    Ailia, 566
+
+    Aipichthys, 441
+
+    Air-bladder, 142
+
+    Akysis, 567
+
+    Albacore, 458
+
+    Albinism, 183
+
+    Alborella, 604
+
+    Albula, 660
+
+    Albulichthys, 596
+
+    Alburnus, 603
+
+    Alepocephalus, 664
+
+    Alestes, 608
+
+    Ale-wife, 659
+
+    Alisphenoid, 56, 88
+
+    Allice Shad, 659
+
+    Alopecias, 322
+
+    Ambassis, 393
+
+    Amblyopsis, 618
+
+    Amblyopus, 489
+
+    Amblypharyngodon, 598
+
+    Amblypterus, 370
+
+    Amblyrhynchichthys, 596
+
+    Amia, 372
+
+    Amioidei, 370
+
+    Amiurus, 567
+
+    Ammocoetes, 693
+
+    Ammodytes, 550
+
+    Ammopleurops, 559
+
+    Ammotretis, 557
+
+    Amphioxus, 696
+
+    Amphipnous, 668
+
+    Amphiprion, 525
+
+    Amphisile, 509
+
+    Amphistium, 442
+
+    Anabas, 516
+
+    Anableps, 617
+
+    Anacanthini, 537
+
+    Anacanthus, 684
+
+    Anacyrtus, 611
+
+    Anal fin, 40, 42
+
+    Anampses, 529
+
+    Anapterus, 582
+
+    Anarrhichas, 492
+
+    Anastomus, 608
+
+    Anchovy, 656
+
+    Ancistrodon, 319
+
+    Ancylodon, 430
+
+    Anema, 463
+
+    Anenchelum, 433
+
+    Angel-fish, 334
+
+    Angler, 470
+
+    Anguilla, 671
+
+    Angular bone, 54, 91
+
+    Anomalops, 449
+
+    Anoplogaster, 422
+
+    Antarctic ocean, 289
+
+    Antennarius, 473
+
+    Anthias, 380
+
+    Anticitharus, 556
+
+    Antigonia, 449
+
+    Aphanopus, 434
+
+    Aphareus, 390
+
+    Aphoristia, 559
+
+    Aphredoderus, 396
+
+    Aphritis, 466
+
+    Aphyocharax, 610
+
+    Aphyocypris, 598
+
+    Aphyonus, 548
+
+    Apionichthys, 559
+
+    Apistus, 415
+
+    Aploactis, 417
+
+    Apocryptes, 487
+
+    Apodichthys, 496
+
+    Apogon, 394
+
+    Apophyses, 51
+
+    Appendices pyloricæ, 131
+
+    Aprion, 397
+
+    Apsilus, 397
+
+    Apua, 606
+
+    Arapaima, 654
+
+    Archæus, 442
+
+    Archipterygium, 74
+
+    Arctic ocean, 261
+
+    Arctic zone, 241
+
+    Argentina, 650
+
+    Arges, 575
+
+    Argyropelecus, 628
+
+    Argyriosus, 443
+
+    Aristotle, 1
+
+    Arius, 569
+
+    Arnoglossus, 556
+
+    Arrhamphus, 621
+
+    Arripis, 393
+
+    Artedi, 9
+
+    Artedius, 480
+
+    Arthropterus, 342
+
+    Articulary bone, 54, 90
+
+    Articulated rays, 40
+
+    Asima, 405
+
+    Aspidoparia, 602
+
+    Aspidophoroides, 480
+
+    Aspidorhynchidæ, 369
+
+    Aspius, 603
+
+    Aspredo, 580
+
+    Aspro, 379
+
+    Astracanthus, 314
+
+    Astrape, 340
+
+    Astrolepis, 354
+
+    Astronesthes, 629
+
+    Astrophysus, 572
+
+    Astroplebus, 575
+
+    Astroptychius, 314
+
+    Ateleopus, 553
+
+    Atherina, 500
+
+    Atherinichthys, 501
+
+    Atlantic, tropical, 278
+
+    Atlantic, northern, 262
+
+    Atopochilus, 570
+
+    Atopomycterus, 689
+
+    Atypichthys, 402
+
+    Auchenaspis, 354
+
+    Auchenipterus, 572
+
+    Auchenoglanis, 569
+
+    Aulacocephalus, 383
+
+    Aulolepis, 631
+
+    Aulichthys, 508
+
+    Auliscops, 507, 508
+
+    Aulopus, 587
+
+    Aulopyge, 596
+
+    Aulorhynchus, 508
+
+    Aulostoma, 507, 508
+
+    Ausonia, 455
+
+    Ausonius, 3
+
+    Autochthont, 214
+
+    Autostylic skull, 71
+
+    Auxis, 459
+
+    Avola, 604
+
+
+    Badis, 418
+
+    Baer, 32
+
+    Bagarius, 570
+
+    Bagrichthys, 567
+
+    Bagroides, 567
+
+    Bagropsis, 568
+
+    Bagrus, 567
+
+    Baird, 29
+
+    Bakker, 32
+
+    Balfour, 32, 33
+
+    Balistes, 684
+
+    Ballan Wrasse, 527
+
+    Band-fish, 490
+
+    Barbel, 594
+
+    Barbels, 37
+
+    Barbichthys, 596
+
+    Barbus, 594
+
+    Barilius, 602
+
+    Barracuda, 437, 499
+
+    Barramunda, 357
+
+    Barynotus, 596
+
+    Basibranchial, 58
+
+    Basihyal, 58
+
+    Basioccipital, 56, 87
+
+    Basisphenoid, 56, 57, 89
+
+    Basking shark, 322
+
+    Bass, 376
+
+    Bastard Dorey, 388
+
+    Bathydraco, 465
+
+    Bathygadus, 552
+
+    Bathylagus, 650
+
+    Bathynectes, 547
+
+    Bathyophis, 629
+
+    Bathypterois, 583
+
+    Bathysaurus, 582
+
+    Bathythrissa, 668
+
+    Bathytroctes, 664
+
+    Batoidei, 335
+
+    Batrachocephalus, 570
+
+    Batrachus, 467
+
+    Bayad, 567
+
+    Bdellostoma, 695
+
+    Becker, 408
+
+    Bellows-fish, 509
+
+    Belodontichthys, 566
+
+    Belon, 3
+
+    Belone, 620
+
+    Belonesox, 617
+
+    Belonostomus, 369
+
+    Bembras, 480
+
+    Benedenius, 370
+
+    Benthophilus, 489
+
+    Berycidæ, 420
+
+    Berycopsis, 421
+
+    Beryx, 422
+
+    Betta, 518
+
+    Bib, 541
+
+    Bichir, 364
+
+    Bitterling, 601
+
+    Black Bass, 393
+
+    Black-fish, 452, 527
+
+    Black Head, 596
+
+    Black Horses, 589
+
+    Black Sea-bream, 406
+
+    Blanchard, 28
+
+    Bleak, 604
+
+    Bleeker, 30
+
+    Bleekeria, 550
+
+    Blenniidæ, 492
+
+    Blenniops, 496
+
+    Blennius, 493
+
+    Blennodesmus, 538
+
+    Blennophis, 498
+
+    Blenny, 492
+
+    Blepsias, 480
+
+    Blind fish, 618
+
+    Bloch, 13
+
+    Blood-corpuscles, 150
+
+    Blue-fish, 447
+
+    Boar-fish, 388, 449
+
+    Bocage, 28
+
+    Bocourt, 31
+
+    Bola, 602
+
+    Boleophthalmus, 487
+
+    Boleosoma, 379
+
+    Bolty, 535
+
+    Bombay-duck, 584
+
+    Bonaparte, 28
+
+    Bonelli, 7
+
+    Bonito, 458
+
+    Bony Pike, 367
+
+    Borer, 694
+
+    Botia, 605
+
+    Bovichthys, 465
+
+    Bow-fin, 372
+
+    Box, 406
+
+    Brachionichthys, 474
+
+    Brachymystax, 646
+
+    Brachypleura, 556
+
+    Brackish water fishes, 250
+
+    Brain, 97
+
+    Brama, 454
+
+    Branched rays, 40
+
+    Branchiæ, 136
+
+    Branchial arches, 58
+
+    Branchiostegals, 39, 58, 91
+
+    Branchiostoma, 696
+
+    Bream, 602
+
+    Bregmaceros, 545
+
+    Brill, 555
+
+    British district, 263
+
+    Brontes, 575
+
+    Brook-trout, 646
+
+    Brosmius, 546
+
+    Brotula, 546
+
+    Brotulophis, 549
+
+    Brünnich, 13
+
+    Brycon, 610
+
+    Bryconæthiops, 610
+
+    Bryconops, 610
+
+    Bryttus, 396
+
+    Buccal cavity, 123
+
+    Bulbus aortæ, 152
+
+    Bull-head, 476
+
+    Bull-trout, 644
+
+    Bulti, 535
+
+    Buffaloe, 589
+
+    Bummaloh, 584
+
+    Bungia, 596
+
+    Bunocephalichthys, 580
+
+    Bunocephalus, 580
+
+    Bunocottus, 480
+
+    Burbot, 544
+
+    Bursa entiana, 128
+
+    Burton Skate, 341
+
+    Butter-fish, 496, 533
+
+    Bynni, 594
+
+    Bythites, 549
+
+
+    Cachius, 604
+
+    Cænotropus, 607
+
+    Cæsio, 390
+
+    Calamoichthys, 364
+
+    Californian district, 271
+
+    Calamostoma, 680
+
+    Callanthias, 381
+
+    Callichrous, 566
+
+    Callichthys, 575
+
+    Callionymus, 489
+
+    Callipteryx, 462
+
+    Callomystax, 573
+
+    Callophysus, 569
+
+    Callorhynchus, 350
+
+    Callyodon, 532
+
+    Camper, 16
+
+    Campostoma, 596
+
+    Cantharina, 405
+
+    Cantharus, 405
+
+    Cantor, 30
+
+    Capelin, 647
+
+    Capello, 28
+
+    Cape of Good Hope, 283
+
+    Capitodus, 405
+
+    Capoëta, 593
+
+    Capros, 449
+
+    Carangidæ, 440
+
+    Carangopsis, 442
+
+    Caranx, 442
+
+    Carapus, 667
+
+    Carassius, 591
+
+    Carboniferous fishes, 196
+
+    Carcharias, 316
+
+    Carchariidæ, 316
+
+    Carcharodon, 320
+
+    Carcharopsis, 319
+
+    Cardlike teeth, 126
+
+    Caribe, 613
+
+    Carmoot, 563
+
+    Carp, 589
+
+    Carpals, 59
+
+    Carpiodes, 589
+
+    Cartilage-bones, 87
+
+    Castelnau, 31
+
+    Cataphracti, 480
+
+    Cat-fishes, 568
+
+    Catla, 592
+
+    Catopra, 418
+
+    Catoprion, 613
+
+    Catostomus, 589
+
+    Caturidæ, 371
+
+    Caudal fin, 40
+
+    Cebidichthys, 498
+
+    Central American district, 279
+
+    Centrarchus, 396
+
+    Centridermichthys, 477
+
+    Centrina, 331
+
+    Centriscus, 509
+
+    Centrolabrus, 528
+
+    Ceutrolepis, 370
+
+    Centrolophus, 452
+
+    Centromochlus, 572
+
+    Centronotus, 496
+
+    Centrophorus, 331
+
+    Centropogon, 417
+
+    Centropomus, 379
+
+    Ceutropristis, 380
+
+    Centroscyllium, 332
+
+    Centrum, 51
+
+    Cephalacanthus, 482
+
+    Cephalaspis, 353
+
+    Cephaloptera, 347
+
+    Cephenoplosus, 368
+
+    Cepola, 490
+
+    Ceratias, 472
+
+    Ceratichthys, 596
+
+    Ceratobranchial, 58
+
+    Ceratodus, 357
+
+    Ceratohyal, 58
+
+    Ceratoptera, 347
+
+    Cerebellum, 97
+
+    Cestracion, 330
+
+    Cestraciontidæ, 328
+
+    Cetengraulis, 656
+
+    Cetopsis, 572
+
+    Chaca, 564
+
+    Chad, 408
+
+    Chænichthys, 466
+
+    Chætobranchus, 537
+
+    Chætodon, 398
+
+    Chætopterus, 390
+
+    Chætostomus, 576
+
+    Chalceus, 610
+
+    Chalcinopsis, 610
+
+    Chalcinus, 610
+
+    Champsodon, 464
+
+    Channa, 513
+
+    Chanodichthys, 604
+
+    Chanos, 662
+
+    Characinidæ, 606
+
+    Characodon, 615
+
+    Charr, 645
+
+    Chasmodes, 494
+
+    Chatoëssus, 657
+
+    Chauliodus, 628
+
+    Chaunax, 474
+
+    Cheilio, 530
+
+    Chela, 604
+
+    Chelmo, 399
+
+    Chiasmodus, 546
+
+    Chilian district, 288
+
+    Chilinus, 528
+
+    Chilobranchus, 669
+
+    Chilodactylus, 411
+
+    Chilodipterus, 395
+
+    Chilomycterus, 689
+
+    Chilorhinus, 674
+
+    Chiloscyllium, 326, 327
+
+    Chimæra, 349
+
+    Chimæridæ, 348
+
+    Chimarrhichthys, 466
+
+    Chiracanthus, 355
+
+    Chirocentrites, 656
+
+    Chirocentrodon, 660
+
+    Chirocentrus, 663
+
+    Chirodon, 609
+
+    Chirodus, 370
+
+    Chirolepis, 370
+
+    Chironemus, 411
+
+    Chirus, 491
+
+    Chlorophthalmus, 587
+
+    Chœrops, 530
+
+    Chologaster, 618
+
+    Chomatodus, 329
+
+    Chondropterygii, 313
+
+    Chondrostei, 360
+
+    Chondrosteus, 363
+
+    Chondrostoma, 600
+
+    Chorda dorsalis, 63
+
+    Chorinemus, 446
+
+    Chorismodactylus, 417
+
+    Chorisochismus, 512
+
+    Chromatophors, 183
+
+    Chromides, 534
+
+    Chromis, 535
+
+    Chrysichthys, 567
+
+    Chrysophrys, 409
+
+    Chub, 596, 599, 600
+
+    Cichla, 536
+
+    Cichlops, 466
+
+    Circulation, organs of, 150
+
+    Cirrhilabrus, 530
+
+    Cirrhina, 596
+
+    Cirrhites, 411
+
+    Cirrhitidæ, 410
+
+    Cirrostomi, 696
+
+    Citharichthys, 556
+
+    Citharinus, 607
+
+    Citharus, 556
+
+    Cladacanthus, 314
+
+    Cladodus, 328
+
+    Clarias, 563
+
+    Clarotes, 567
+
+    Claspers, 167
+
+    Clavicula, 59, 92
+
+    Clepticus, 530
+
+    Climbing Perch, 516
+
+    Clinus, 495
+
+    Cloudy Bay cod, 549
+
+    Clupea, 658
+
+    Clupeichthys, 660
+
+    Clupeoides, 660
+
+    Cnidoglanis, 564
+
+    Coal-fish, 541
+
+    Cobitis, 605
+
+    Coccia, 628
+
+    Coccosteus, 351
+
+    Cochlognathus, 596
+
+    Cochliodus, 329
+
+    Cock-and-hen Paddle, 484
+
+    Cod-fishes, 539
+
+    Cœcal stomach, 130
+
+    Coelacanthidæ, 365
+
+    Coelodus, 367
+
+    Coelogaster, 656
+
+    Coelonotus, 681
+
+    Coelorhynchus, 433
+
+    Coffer-fish, 686
+
+    Coilia, 657
+
+    Collichthys, 430
+
+    Commerson, 13
+
+    Conger, 673
+
+    Congrogadina, 550
+
+    Congromuræna, 674
+
+    Conodon, 386
+
+    Conodonts, 193
+
+    Conodus, 368
+
+    Conorhynchus, 569
+
+    Conus arteriosus, 151
+
+    Cook, 527
+
+    Copidoglanis, 564
+
+    Coracoid, 59, 92
+
+    Coral-fishes, 397, 525
+
+    Corax, 317
+
+    Coregonus, 647
+
+    Coridodax, 533
+
+    Coris, 530
+
+    Cork-wing, 527
+
+    Cornide, 13
+
+    Corpora quadrigemina, 103
+
+    Corpora restiformia, 99
+
+    Corpora striata, 100
+
+    Corvina, 430
+
+    Corvo, 429
+
+    Corynopoma, 607
+
+    Coryphæna, 452
+
+    Coryphænoides, 552
+
+    Cosmolepis, 370
+
+    Cosmoptychius, 370
+
+    Cossyphus, 528
+
+    Costa, 28
+
+    Cottoperca, 466
+
+    Cottus, 476
+
+    Cotylis, 512
+
+    Couch, 27
+
+    Couchia, 544
+
+    Craig-fluke, 557
+
+    Creagrutus, 610
+
+    Cremnobates, 495
+
+    Crenicichla, 537
+
+    Crenidens, 406
+
+    Crenilabrus, 527
+
+    Crenuchus, 612
+
+    Crepidogaster, 513
+
+    Cretaceous fishes, 199
+
+    Cricacanthus, 314
+
+    Cristiceps, 495
+
+    Crossochilus, 596
+
+    Crossognathus, 656
+
+    Crossorhinus, 328
+
+    Crossostoma, 604
+
+    Crucian carp, 591
+
+    Crura cerebri, 98
+
+    Cryptacanthodes, 496
+
+    Cryptopterus, 566
+
+    Ctenododipteridæ, 359
+
+    Ctenodus, 359
+
+    Ctenoid scales, 46
+
+    Ctenolabrus, 527
+
+    Ctenopharyngodon, 601
+
+    Ctenopoma, 516
+
+    Ctenoptychius, 329
+
+    Cubiceps, 456
+
+    Culter, 604
+
+    Curimatus, 607
+
+    Cut-lips, 596
+
+    Cuvier, 17
+
+    Cyathaspis, 354
+
+    Cybium, 459
+
+    Cyclobatis, 340
+
+    Cycloid scales, 46
+
+    Cyclopoma, 375
+
+    Cyclopterus, 484
+
+    Cycloptychius, 370
+
+    Cyclostomata, 691
+
+    Cyclurus, 588
+
+    Cyema, 670
+
+    Cymolutes, 530
+
+    Cynodon, 611
+
+    Cynoglossus, 558
+
+    Cynolebias, 615
+
+    Cyprinidæ, 587
+
+    Cyprinion, 598
+
+    Cyprinodon, 614
+
+    Cyprinoid division, 217
+
+    Cyprinus, 589
+
+    Cyttidæ, 450
+
+    Cyttus, 451
+
+
+    Dab, 557
+
+    Dace, 599, 600
+
+    Dactylopterus, 481
+
+    Dactyloscopus, 498
+
+    Dangila, 596
+
+    Danio, 602
+
+    Dascyllus, 525
+
+    Datnioides, 397
+
+    Daurade, 409
+
+    Day, 30
+
+    Deal-fish, 522
+
+    Decodon, 530
+
+    Deep-sea fishes, 296
+
+    Dekay, 29
+
+    Dendrodus, 365
+
+    Dentary, 54, 91
+
+    Dentex, 389
+
+    Dercetis, 666
+
+    Dermal spines, 53
+
+    Dermoskeleton, 85
+
+    Devil-fishes, 344
+
+    Devonian fishes, 193, 194
+
+    Diagramma, 386
+
+    Diana, 455
+
+    Dibranchus, 475
+
+    Dicerobatis, 347
+
+    Dicotylichthys, 689
+
+    Dicrotus, 437
+
+    Dictyosoma, 498
+
+    Didymaspis, 354
+
+    Digestion, organs of, 121
+
+    Dimeracanthus, 314
+
+    Dinematichthys, 549
+
+    Dinichthys, 352
+
+    Diodon, 689
+
+    Dioecious, 157
+
+    Diplocrepis, 513
+
+    Diplomystax, 569
+
+    Diplophos, 629
+
+    Diploprion, 383
+
+    Diplopterus, 365
+
+    Dipnoi, 355
+
+    Dipterodon, 406
+
+    Dipterus, 359
+
+    Diptychus, 595
+
+    Diretmus, 449
+
+    Discoboli, 483
+
+    Discognathus, 593
+
+    Discopyge, 340
+
+    Distichodus, 612
+
+    Ditrema, 534
+
+    Dog-fishes, 325, 619
+
+    Doliichthys, 487
+
+    Dolphins, 453
+
+    Domesticated fishes, 185
+
+    Domine, 436
+
+    Donovan, 17
+
+    Doras, 572
+
+    Doratonotus, 530
+
+    Dorsal fin, 40
+
+    Dorsch, 540
+
+    Dory, 450
+
+    Doryichthys, 681
+
+    Doydixodon, 406
+
+    Dragonet, 489
+
+    Drepane, 402
+
+    Drepanephorus, 331
+
+    Drum, 427
+
+    Ductor, 442
+
+    Ductus choledochus, 133
+
+    Ductus cysticus, 133
+
+    Duhamel, 13
+
+    Dules, 384
+
+    Duméril, 33
+
+    Dussumieria, 662
+
+    Duverney, 7
+
+    Duymæria, 530
+
+
+    Eagle-Rays, 344
+
+    Ear, 116
+
+    Echeneis, 460
+
+    Echinorhinus, 333
+
+    Echiostoma, 629
+
+    Ectopterygoid, 90
+
+    Edaphodon, 349
+
+    Eel, 671
+
+    Eel-pout, 544
+
+    Egertonia, 526
+
+    Elacate, 460
+
+    Elasmodus, 349
+
+    Elasmognathus, 349
+
+    Electric Eel, 667
+
+    Electric organs, 94
+
+    Electric Rays, 339
+
+    Electric Sheath-fish, 574
+
+    Eleotris, 488
+
+    Elonichthys, 370
+
+    Elopichthys, 604
+
+    Elops, 661
+
+    Embiotocidæ, 533
+
+    Encheliophis, 549
+
+    Enchelycore, 677
+
+    Enchodus, 433
+
+    Endoskeleton, 85
+
+    Engraulis, 656
+
+    Enneodon, 687
+
+    Enoplosus, 380
+
+    Entopterygoid, 55, 90
+
+    Epalzeorhynchus, 596
+
+    Ephippus, 402
+
+    Epibranchial, 59
+
+    Epibulus, 528
+
+    Epicoracoid, 59
+
+    Epididymis, 167
+
+    Epigionichthys, 696
+
+    Epihyal, 58
+
+    Epinnula, 436
+
+    Epioticum, 88
+
+    Epiphysis, 98
+
+    Epitympanic, 55
+
+    Equatorial zone, 218, 272
+
+    Eques, 431
+
+    Equula, 449
+
+    Eremophilus, 581
+
+    Erethistes, 580
+
+    Ericymba, 596
+
+    Erythrichthys, 391
+
+    Erythrinus, 607
+
+    Escholar, 437
+
+    Esox, 624
+
+    Etelis, 397
+
+    Etheostomatidæ, 379
+
+    Ethmoid, 57, 89
+
+    Etroplus, 534
+
+    Etrumeus, 662
+
+    Euanemus, 572
+
+    Euctenogobius, 487
+
+    Euglyptosternum, 571
+
+    Eugnathus, 368
+
+    Eulachon, 647
+
+    Eulepidotus, 368
+
+    Euoxymetopon, 434
+
+    Euprotomicrus, 334
+
+    Europo-Asiatic region, 243
+
+    Eurynotus, 370
+
+    Eurypholis, 666
+
+    Eurysomus, 370
+
+    Eustira, 604
+
+    Eutropiichthys, 566
+
+    Eutropius, 566
+
+    Evorthodus, 487
+
+    Exoccipital, 56, 87
+
+    Exocoetus, 621
+
+    Exoglossum, 596
+
+    Exostoma, 580
+
+    Eye, 36, 111
+
+
+    Fabricius, 13
+
+    Fall-fish, 600
+
+    Fierasfer, 549
+
+    Fighting-fish, 519
+
+    File-fishes, 684
+
+    Fins, 40
+
+    Fishing-Frog, 470
+
+    Fistularia, 507, 508
+
+    Fitzroyia, 615
+
+    Flat-fishes, 553
+
+    Flounder, 557
+
+    Flute-mouth, 507
+
+    Flying-fish, 621
+
+    Flying Gurnard, 482
+
+    Forskal, 13
+
+    Forster, 13
+
+    Freshwater-fishes, 208
+
+    Freshwater-Herring, 645
+
+    Fries and Ekström, 27
+
+    Frog-fish, 470
+
+    Frontal bone, 57, 89
+
+    Frost-fish, 436
+
+    Fuegian sub-region, 248
+
+    Fundulus, 615
+
+
+    Gadiculus, 541
+
+    Gadidæ, 539
+
+    Gadopsis, 537
+
+    Gadus, 539
+
+    Galapagoes district, 280
+
+    Galaxias, 624
+
+    Galeichthys, 569
+
+    Galeocerdo, 317
+
+    Galeoides, 425
+
+    Galeus, 318
+
+    Gallo, 451
+
+    Gambusia, 616
+
+    Ganodus, 349
+
+    Ganoidei, 350
+
+    Ganoid scales, 47
+
+    Gar-pike, 367, 620
+
+    Gaspereau, 659
+
+    Gastrochisma, 455
+
+    Gastrocnemus, 452
+
+    Gastromyzon, 604
+
+    Gastropelecus, 610
+
+    Gastrosteus, 505
+
+    Gastrotokeus, 682
+
+    Gazza, 450
+
+    Gegenbaur, 32
+
+    Gempylus, 437
+
+    Genidens, 569
+
+    Genyoroge, 384
+
+    Genypterus, 549
+
+    Geoffroy, 33
+
+    Geophagus, 537
+
+    Geotria, 693
+
+    Gerres, 388
+
+    Gillaroo, 645
+
+    Gill-cover, 38
+
+    Gill-opening, 38
+
+    Gill-rakers, 59, 139
+
+    Gills, 136
+
+    Gilthead, 409
+
+    Ginglymostoma, 326
+
+    Girardinus, 618
+
+    Girella, 406
+
+    Glanidium, 572
+
+    Glanis, 566
+
+    Glaucosoma, 384
+
+    Globe-fish, 687
+
+    Glossohyal, 58
+
+    Glottis, 149
+
+    Glut, 673
+
+    Glutinous hag, 694
+
+    Glyphidodon, 525
+
+    Glyptauchen, 415
+
+    Glyptolæmus, 365
+
+    Glyptolepis, 365
+
+    Glyptopomus, 365
+
+    Glyptosternum, 572
+
+    Gmelin, 13
+
+    Gobiesocidæ, 510
+
+    Gobiesox, 513
+
+    Gobio, 595
+
+    Gobiodon, 487
+
+    Gobiosoma, 487
+
+    Gobius, 486
+
+    Goby, 486
+
+    Gold-fish, 591
+
+    Gold-Sinny, 527
+
+    Gomphodus, 319
+
+    Gomphosus, 530
+
+    Gonatodus, 370
+
+    Goniognathus, 452
+
+    Gonorhynchus, 652
+
+    Gonostoma, 629
+
+    Gourami, 517
+
+    Grammistes, 382
+
+    Granular teeth, 126
+
+    Graphiurus, 365
+
+    Grayling, 649
+
+    Greenland Shark, 333
+
+    Grey Mullet, 501
+
+    Grig, 673
+
+    Gronow, 12
+
+    Growler, 393
+
+    Growth of Fishes, 170
+
+    Grystes, 392
+
+    Gudgeon, 596
+
+    Gular plates, 80
+
+    Güldenstedt, 13
+
+    Gunellichthys, 498
+
+    Gunnel-fish, 496
+
+    Günther, 27, 30
+
+    Gurnard, 479
+
+    Gwyniad, 649
+
+    Gymnachirus, 558
+
+    Gymnarchus, 626
+
+    Gymnelis, 538
+
+    Gymnocrotaphus, 406
+
+    Gymnocypris, 595
+
+    Gymnomuræna, 677
+
+    Gynmoscopelus, 585
+
+    Gymnotus, 667
+
+    Gyracanthus, 314
+
+    Gyrodus, 367
+
+    Gyropristis, 314
+
+    Gyroptychius, 365
+
+
+    Haddock, 540
+
+    Hadot, 540
+
+    Hæmal arches, 86
+
+    Hæmal spine, 52
+
+    Hæmapophyses, 51
+
+    Hæmulon, 386
+
+    Hag-fish, 694
+
+    Hair-tail, 436
+
+    Hake, 542
+
+    Halargyreus, 541
+
+    Halec, 656
+
+    Halecidæ, 656
+
+    Half-beak, 621
+
+    Halidesmus, 549
+
+    Halieutæa, 475
+
+    Halieutichthys, 475
+
+    Haliophis, 550
+
+    Haller, 16
+
+    Haloporphyrus, 543
+
+    Halosauridæ, 665
+
+    Hamilton, 17
+
+    Hammerhead, 318
+
+    Hapalogenys, 386
+
+    Haplochilus, 615
+
+    Haplochiton, 651
+
+    Haplodactylina, 406
+
+    Hapuku, 392
+
+    Harpagifer, 467
+
+    Harpodon, 583
+
+    Harttia, 580
+
+    Hasse, 32
+
+    Hasselquist, 13
+
+    Hausen, 361
+
+    Head, 36
+
+    Heart, 150
+
+    Heckel, 28
+
+    Hector, 32
+
+    Heliastes, 525
+
+    Helicophagus, 566
+
+    Heliodus, 359
+
+    Helmichthys, 180
+
+    Helogenes, 567
+
+    Helotes, 385
+
+    Hemerocœtes, 491
+
+    Hemichromis, 535
+
+    Hemiculter, 604
+
+    Hemigaleus, 319
+
+    Hemigymnus, 530
+
+    Hemilepidotus, 480
+
+    Hemiodus, 607
+
+    Hemipimelodus, 569
+
+    Hemipristis, 317
+
+    Hemirhamphus, 621
+
+    Hemirhombus, 556
+
+    Hemirhynchus, 437
+
+    Hemisaurida, 582
+
+    Hemisilurus, 566
+
+    Hemisorubim, 568
+
+    Hemithyrsites, 434
+
+    Hemitrichas, 656
+
+    Hemitripterus, 417
+
+    Heniochus, 399
+
+    Heptanchus, 325
+
+    Heptapterus, 581
+
+    Hermaphroditism, 157
+
+    Heros, 536
+
+    Herring, 658
+
+    Heteracanth, 41
+
+    Heterobranchus, 563
+
+    Heterocercy, 80
+
+    Heteroconger, 674
+
+    Heterognathodon, 389
+
+    Heterolepidotidæ, 491
+
+    Heteropygii, 618
+
+    Heterostichus, 498
+
+    Heterotis, 655
+
+    Hexanchus, 325
+
+    Hexapsephus, 588
+
+    Himantolophus, 472
+
+    Hippocampus, 683
+
+    Hippoglossoides, 555
+
+    Hippoglossus, 555
+
+    Histiophorus, 431
+
+    Histiopterus, 387
+
+    Holacanthus, 400
+
+    Holibut, 555
+
+    Hollardia, 684
+
+    Holocentrum, 423
+
+    Holocephala, 348
+
+    Holophagus, 365
+
+    Holoptychidæ, 365
+
+    Holosteus, 619
+
+    Homacanth, 41
+
+    Homaloptera, 604
+
+    Hombron et Jacquinot, 27
+
+    Homelyn Ray, 341
+
+    Homocanthus, 314
+
+    Homocercy, 83
+
+    Homoeolepis, 366
+
+    Homonotus, 421
+
+    Hopladelus, 568
+
+    Hoplichthys, 478
+
+    Hoplognathus, 410
+
+    Hoplopleuridæ, 665
+
+    Hoplopteryx, 421
+
+    Hoplopygus, 365
+
+    Hoplostethus, 421
+
+    Hoplunnis, 674
+
+    Horse-mackerel, 442
+
+    Hounds, 319
+
+    Huchen, 645
+
+    Humeral arch, 59
+
+    Hunds-fish, 619
+
+    Hunter, 16
+
+    Huro, 393
+
+    Hutton, 32
+
+    Huxley, 33
+
+    Hybernation, 188
+
+    Hybodontidæ, 328
+
+    Hybognathus, 596
+
+    Hyborhynchus, 596
+
+    Hybridism, 178
+
+    Hydrocyon, 611
+
+    Hygrogonus, 536
+
+    Hyodon, 653
+
+    Hyoid arch, 58
+
+    Hyomandibular, 55, 89
+
+    Hyoprorus, 674
+
+    Hyoptopoma, 578
+
+    Hyostylic skull, 74
+
+    Hypamia, 372
+
+    Hyperoglyphe, 387
+
+    Hyperopisus, 625
+
+    Hypnos, 340
+
+    Hypobranchial, 58
+
+    Hypomessus, 647
+
+    Hypophthalmichthys, 602
+
+    Hypophthalmus, 566
+
+    Hypophysis, 98
+
+    Hypotympanic, 55
+
+    Hypsinotus, 402
+
+    Hypsodon, 500
+
+    Hypural, 53, 84
+
+    Hyrtl, 32
+
+    Hysterocarpus, 534
+
+    Hystricodon, 611
+
+
+    Icelus, 477
+
+    Ichthyborus, 612
+
+    Ichthyocampus, 681
+
+    Ichthyodorulites, 194
+
+    Ichthyomyzon, 693
+
+    Id, 599
+
+    Ikan sumpit, 403
+
+    Impregnation, artificial, 186
+
+    Indian region, 220
+
+    Indo-Pacific ocean, 278
+
+    Infraorbital, 54
+
+    Infundibulum, 98
+
+    Interhæmals, 53
+
+    Intermaxillary, 53
+
+    Interneurals, 53
+
+    Interoperculum, 38, 55, 91
+
+    Intestine, 127
+
+    Ipnops, 585
+
+    Ischyodus, 349
+
+    Ischyrocephalus, 666
+
+    Isistius, 334
+
+    Isthmus, 39, 58
+
+    Isurus, 457
+
+
+    Japanese District, 270
+
+    Jenyns, 27
+
+    Jenynsia, 616
+
+    John Dory, 451
+
+    Jugular fins, 42
+
+    Julis, 529
+
+
+    Kabeljau, 540
+
+    Kalm, 13
+
+    Kamtschatkan district, 269
+
+    Karausche, 591
+
+    Karpfen, 589
+
+    Kathetostoma, 463
+
+    Kaup, 33
+
+    Kelb el bahr, 611
+
+    Kelb el moyeh, 611
+
+    Kelp-fish, 533
+
+    Keris, 440
+
+    Ketengus, 569
+
+    Kidney, 155
+
+    King of the herrings, 522
+
+    Klein, 12
+
+    Klipvisch, 549
+
+    Klunzinger, 30
+
+    Kner, 27, 28
+
+    Kneria, 606
+
+    Kokopu, 625
+
+    Kölliker, 32
+
+    Kovalevsky, 33
+
+    Kröyer, 27
+
+    Kurtus, 425
+
+
+    Labberdan, 540
+
+    Labeo, 593
+
+    Labials, 64, 69
+
+    Labrax, 376
+
+    Labrichthys, 530
+
+    Labridæ, 525
+
+    Labroides, 530
+
+    Labrus, 526
+
+    Labyrinthici, 514
+
+    Lachnolæmus, 528
+
+    Lachs, 644
+
+    Lacépède, 15
+
+    Lactarius, 450
+
+    Ladislavia, 596
+
+    Læmargus, 333
+
+    Læmonema, 543
+
+    Læops, 557
+
+    Lais, 566
+
+    Laminæ branchiales, 136
+
+    Lamna, 320
+
+    Lamnidæ, 319
+
+    Lampern, 692
+
+    Lampris, 454
+
+    Lamprey, 692
+
+    Lancelet, 696
+
+    Lanioperca, 397
+
+    Larimus, 431
+
+    Lateral line, 48
+
+    Lates, 377
+
+    Latilus, 466
+
+    Latris, 412
+
+    Latrunculus, 486
+
+    Launce, 550
+
+    Leather-carp, 591
+
+    Lebiasina, 607
+
+    Lemon-sole, 558
+
+    Lentipes, 487
+
+    Lepadogaster, 513
+
+    Lepidoblennius, 498
+
+    Lepidocephalichthys, 606
+
+    Lepidocephalus, 606
+
+    Lepidocottus, 476
+
+    Lepidopsetta, 556
+
+    Lepidopus, 435
+
+    Lepidosiren, 355
+
+    Lepidosteidæ, 367
+
+    Lepidotrigla, 479
+
+    Lepidotus, 368
+
+    Lepidozygus, 525
+
+    Leporinus, 608
+
+    Lepracanthus, 314
+
+    Leptacanthus, 314
+
+    Leptobarbus, 597
+
+    Leptocarcharias, 319
+
+    Leptocardii, 696
+
+    Leptocephali, 179
+
+    Leptoichthys, 681
+
+    Leptojulis, 529
+
+    Leptolepidæ, 371
+
+    Leptopterygius, 513
+
+    Leptoscopus, 463
+
+    Leptosomus, 656
+
+    Leptotrachelus, 666
+
+    Lesson, 26
+
+    Lethrinus, 407
+
+    Leucaspius, 604
+
+    Leuciscus, 598
+
+    Leucosomus, 600
+
+    Liacanthus, 314
+
+    Liachirus, 558
+
+    Liassic fishes, 198
+
+    Lichia, 446
+
+    Ligamentum longitudinale, 72
+
+    Limnurgus, 615
+
+    Ling, 544, 549
+
+    Linnæus, 10
+
+    Liocassis, 567
+
+    Liopsetta, 556
+
+    Lioscorpius, 415
+
+    Liparis, 485
+
+    Liposarcus, 576
+
+    Liver, 132
+
+    Loach, 604
+
+    Lobotes, 387
+
+    Lonchurus, 431
+
+    Lophiogobius, 487
+
+    Lophiosilurus, 569
+
+    Lophiostomus, 368
+
+    Lophius, 470
+
+    Lophobranchii, 678
+
+    Lophonectes, 556
+
+    Loricaria, 578
+
+    Lota, 544
+
+    Lotella, 543
+
+    Loxodon, 319
+
+    Lucania, 615
+
+    Lucifuga, 547
+
+    Luciocephalidæ, 519
+
+    Luciogobius, 489
+
+    Lucioperca, 378
+
+    Luciosoma, 598
+
+    Luciotrutta, 646
+
+    Lump-sucker, 484
+
+    Lütken, 32
+
+    Lycodes, 537
+
+
+    Mackerel, 456, 457
+
+    Mackerel Midge, 544
+
+    Macrodon, 607
+
+    Macrolepis, 421
+
+    Macrones, 567
+
+    Macropoma, 365
+
+    Macropus, 517
+
+    Macrosemius, 368
+
+    Macruridæ, 557
+
+    Macruronus, 552
+
+    Macrurus, 552
+
+    Mæna, 390
+
+    Mahaseer, 594
+
+    Malacanthus, 467
+
+    Malacocephalus, 552
+
+    Malacopterus, 528
+
+    Malacopterygian, 41
+
+    Malacosteus, 629
+
+    Malapterurus, 574
+
+    Mallotus, 647
+
+    Malpighi, 7
+
+    Malpighian corpuscle, 155
+
+    Malthe, 475
+
+    Mandible, 54
+
+    Margrav, 7
+
+    Marine fishes, 254
+
+    Mary sole, 555
+
+    Maskinonge, 624
+
+    Mastacembelus, 498
+
+    Mastoid, 57, 88
+
+    Maurolicus, 628
+
+    Maynea, 538
+
+    Maxillary, 53, 90
+
+    Meagre, 427
+
+    Meckel’s cartilage, 54
+
+    Meda, 601
+
+    Mediterranean  district, 264
+
+    Medulla oblongata, 98
+
+    Megalichthys, 365
+
+    Megalobrycon, 610
+
+    Megalops, 661
+
+    Meidinger, 13
+
+    Melamphaes, 423
+
+    Melanocetus, 473
+
+    Melanonus, 541
+
+    Membrane-bones, 75, 84
+
+    Mendosoma, 412
+
+    Mene, 455
+
+    Menhaden, 659
+
+    Merluccius, 542
+
+    Mesencephalon, 97
+
+    Mesoarium, 158
+
+    Mesodon, 367
+
+    Mesogaster, 500
+
+    Mesolepis, 370
+
+    Mesonauta, 536
+
+    Mesoprion, 384
+
+    Mesops, 537
+
+    Mesopterygium, 70
+
+    Mesotympanic, 55
+
+    Mesturus, 367
+
+    Metacarpals, 59
+
+    Metamorphosis, 170
+
+    Metapterygium, 70
+
+    Metapterygoid, 55, 90
+
+    Metencephalon, 97
+
+    Micracanthus, 519
+
+    Microconodus, 370
+
+    Microdesmus, 538
+
+    Microdon, 367
+
+    Micropogon, 428
+
+    Micropteryx, 443
+
+    Micropus, 416
+
+    Microstoma, 650
+
+    Miller’s-thumb, 476
+
+    Minnow, 596, 599
+
+    Minous, 417
+
+    Misgurnus, 604
+
+    Mishcup, 408
+
+    Mitchell, 17
+
+    Mixogamous, 177
+
+    Mollienesia, 617
+
+    Molva, 544
+
+    Monacanthus, 684
+
+    Monk-fish, 334
+
+    Monocentris, 421
+
+    Monocirrhus, 418
+
+    Monopterus, 669
+
+    Moon-eye, 653
+
+    Mora, 541
+
+    Mordacia, 693
+
+    Moringua, 675
+
+    Mormyrops, 626
+
+    Mormyrus, 625
+
+    Mossbanker, 659
+
+    Motella, 544
+
+    Mouth, 37, 123
+
+    Moxostoma, 589
+
+    Mud-fish, 372, 619
+
+    Mugil, 501
+
+    Müller, H., 33
+
+    Müller, J., 22, 32, 33
+
+    Müller, O. F., 13
+
+    Müller, W., 33
+
+    Mullidæ, 403
+
+    Mulloides, 404
+
+    Mullus, 404
+
+    Munro, 16
+
+    Muræna, 675
+
+    Murænesox, 674
+
+    Murænichthys, 674
+
+    Murænolepis, 545
+
+    Murray-Cod, 392
+
+    Muscles, 93
+
+    Muskellunge, 624
+
+    Mustelus, 318
+
+    Mylesinus, 613
+
+    Myletes, 613
+
+    Myliobatis, 344
+
+    Mylocyprinus, 588
+
+    Myloleucus, 601
+
+    Mylopharodon, 601
+
+    Myology, 93
+
+    Myriacanthus, 314
+
+    Myriodon, 383
+
+    Myriolepis, 370
+
+    Myripristis, 423
+
+    Myroconger, 677
+
+    Myrophis, 674
+
+    Myrus, 674
+
+    Mystacoleucus, 598
+
+    Myxine, 695
+
+    Myxodes, 498
+
+    Myxus, 504
+
+
+    Nandus, 418
+
+    Nannœthiops, 610
+
+    Nannobrachium, 587
+
+    Nannocampus, 681
+
+    Nannocharax, 608
+
+    Nannostomus, 607
+
+    Narcine, 340
+
+    Naseus, 438, 440
+
+    Nauclerus, 446
+
+    Naucrates, 444
+
+    Nautichthys, 480
+
+    Nealotus, 434
+
+    Nearctic region, 246
+
+    Nebris, 431
+
+    Nebrius, 326
+
+    Neetroplus, 536
+
+    Nefasch, 612
+
+    Nemacanthus, 314
+
+    Nemachilus, 605
+
+    Nemadactylus, 412
+
+    Nematogenys, 581
+
+    Nematops, 557
+
+    Nematoptychius, 370
+
+    Nemichthys, 670
+
+    Nemophis, 498
+
+    Nemopteryx, 434, 539
+
+    Neochanna, 624
+
+    Neoclinus, 498
+
+    Neoconger, 674
+
+    Neophrynichthys, 469
+
+    Neotropical region, 233
+
+    Nerfling, 599
+
+    Nerophis, 681
+
+    Nerves, 103
+
+    Nesiarchus, 434
+
+    Nettastoma, 674
+
+    Neural arches, 85
+
+    Neural spine, 52
+
+    Neurapophyses, 51
+
+    Neurology, 96
+
+    Neuroskeleton, 85
+
+    New Zealand sub-region, 248
+
+    Nictitating  membrane, 113
+
+    Nilsson, 27
+
+    Niphon, 397
+
+    Nomeidæ, 455
+
+    Nomeus, 456
+
+    Nonnat, 501
+
+    Nordmann, 28
+
+    North American district, 266
+
+    North American region, 246
+
+    North Atlantic, 262
+
+    Northern temperate zone, 262
+
+    Northern zone, 240
+
+    North Pacific, 268
+
+    Nostrils, 37, 109
+
+    Notacanthus, 523
+
+    Notidanus, 325
+
+    Notochord, 63
+
+    Notoglanis, 569
+
+    Notograptus, 498
+
+    Notopterus, 665
+
+    Notothenia, 466
+
+    Noturus, 568
+
+    Novacula, 529
+
+    Nummopalatus, 526
+
+    Nuria, 598
+
+    Nutrition, organs of, 121
+
+
+    Oar-Fish, 522
+
+    Oblata, 406
+
+    Occipital, 56
+
+    Ochetobius, 602
+
+    Odax, 532
+
+    Odontaspis, 321
+
+    Odonteus, 525
+
+    Odontostomus, 587
+
+    Oil-sardine, 660
+
+    Old Red Sandstone, 194
+
+    Old wife, 406
+
+    Olfactory lobes, 97
+
+    Olfactory organ, 109
+
+    Oligorus, 392
+
+    Oligosarcus, 611
+
+    Olistherops, 533
+
+    Ombre, 429
+
+    Ombre chevalier, 645
+
+    Omentum, 132
+
+    Onchus, 314
+
+    Oncorhynchus, 646
+
+    Oneirodes, 473
+
+    Oolithic fishes, 199
+
+    Opercular gill, 138
+
+    Operculum, 38, 54, 91
+
+    Ophichthys, 674
+
+    Ophidiidæ, 546
+
+    Ophidium, 549
+
+    Ophiocephalidæ, 513
+
+    Ophiodon, 491
+
+    Ophiopsis, 368
+
+    Opisthognathus, 466
+
+    Opisthopteryx, 656
+
+    Opisthoticum, 88
+
+    Opsariichthys, 602
+
+    Optic lobes, 97
+
+    Oracanthus, 314
+
+    Orbitosphenoid, 57, 88
+
+    Oreinus, 595
+
+    Oreonectes, 606
+
+    Orestias, 615
+
+    Orfe, 599
+
+    Orthacanthus, 334
+
+    Orthagoriscus, 690
+
+    Orthodon, 601
+
+    Orthostomus, 489
+
+    Osbeck, 13
+
+    Osmeroides, 582, 631
+
+    Osmerus, 646
+
+    Os operculare, 91
+
+    Osphromenus, 517
+
+    Osteobrama, 604
+
+    Osteochilus, 596
+
+    Osteogeniosus, 569
+
+    Osteoglossum, 654
+
+    Osteolepis, 365
+
+    Ostracion, 686
+
+    Os transversum, 56
+
+    Otolith, 116
+
+    Otolithus, 430
+
+    Oulachon, 647
+
+    Ovaries, 158, 166
+
+    Ovum, 158, 159, 167
+
+    Owen, 33
+
+    Oxuderces, 489
+
+    Oxyconger, 674
+
+    Oxydoras, 572
+
+    Oxygnathus, 370
+
+    Oxymetopon, 489
+
+    Oxyrhina, 320
+
+    Oxytes, 319
+
+
+    Pachycormus, 368
+
+    Pachymetopon, 406
+
+    Pachyurus, 430
+
+    Pagellus, 408
+
+    Pagrus, 408
+
+    Paired fins, 42
+
+    Palæarctic region, 243
+
+    Palæichthyes, 312
+
+    Palæogadus, 539
+
+    Palæoniscidæ, 369
+
+    Palæorhynchus, 437
+
+    Palæeoscyllium, 326
+
+    Palæospinax, 330
+
+    Palatine, 56, 90
+
+    Palatine arch, 55
+
+    Palimphyes, 457
+
+    Pallas, 13
+
+    Pammelas, 447
+
+    Pancreas, 133
+
+    Pangasius, 566
+
+    Pantodon, 653
+
+    Papilla urogenitalis, 156
+
+    Paracanthobrama, 598
+
+    Paradiplomystax, 569
+
+    Paradise-fish, 517
+
+    Paragoniates, 610
+
+    Paralepis, 585
+
+    Paralichthys, 556
+
+    Paramisgurnus, 606
+
+    Paramyrus, 674
+
+    Paraperca, 375
+
+    Paraphoxinus, 601
+
+    Parapophyses, 51
+
+    Parascopelus, 582
+
+    Parascyllium, 326
+
+    Parasphenoid, 56, 89
+
+    Pardachirus, 558
+
+    Paretroplus, 535
+
+    Parietals, 57, 89
+
+    Pariodon, 581
+
+    Parker, 32
+
+    Parma, 525
+
+    Parnell, 27
+
+    Paroccipital, 56, 88
+
+    Parodon, 607
+
+    Parophrys, 557
+
+    Paropsis, 450
+
+    Parra, 13
+
+    Parr-marks, 631
+
+    Parrot-wrasses, 530
+
+    Patæcus, 497
+
+    Patagonian district, 289
+
+    Peal, 644
+
+    Pectoral arch, 92
+
+    Pectoral fins, 42
+
+    Pediculati, 469
+
+    Pegasus, 482
+
+    Pelagic fishes, 292
+
+    Pelamys, 459
+
+    Pelargorhynchus, 666
+
+    Pelecus, 604
+
+    Pelerin, 322
+
+    Pellona, 660
+
+    Pellonula, 660
+
+    Pelor, 417
+
+    Pelotrophus, 604
+
+    Peltorhamphus, 557
+
+    Pempheris, 425
+
+    Pennant, 13
+
+    Pentaceros, 397
+
+    Pentanemus, 425
+
+    Pentapus, 390
+
+    Pentaroge, 417
+
+    Perca, 375
+
+    Percalabrax, 378
+
+    Perch, 375
+
+    Percichthys, 376
+
+    Percidæ, 375
+
+    Percilia, 397
+
+    Percis, 464
+
+    Percophis, 466
+
+    Percopsis, 651
+
+    Periophthalmus, 487
+
+    Peristethus, 481
+
+    Permian fishes, 197
+
+    Peruvian district, 280
+
+    Pesce Rey, 501
+
+    Petalopteryx, 480
+
+    Petenia, 536
+
+    Peters, 31
+
+    Petrodus, 329
+
+    Petromyzon, 692
+
+    Petrosal, 56
+
+    Petroscirtes, 494
+
+    Phaneropleuridæ, 360
+
+    Pharyngeal bones, 58
+
+    Pharyngognathi, 523
+
+    Pholidichthys, 498
+
+    Pholidophorus, 368
+
+    Photichthys, 629
+
+    Phractocephalus, 568
+
+    Phrynorhombus, 555
+
+    Phycis, 543
+
+    Phyllodus, 526
+
+    Phyllopteryx, 682
+
+    Physiculus, 543
+
+    Physostomi, 559
+
+    Piabuca, 610
+
+    Piabucina, 610
+
+    Pickerell, 624
+
+    Pike, 624
+
+    Pike-perch, 378
+
+    Pilchard, 660
+
+    Pileoma, 379
+
+    Pilot-fish, 444
+
+    Pimelepterus, 410
+
+    Pimelodus, 568
+
+    Pimephales, 596
+
+    Pinguipes, 466
+
+    Pipe-fishes, 680
+
+    Piramutana, 568
+
+    Piratinga, 568
+
+    Pirinampus, 569
+
+    Piso, 7
+
+    Pituitary gland, 98
+
+    Placodermi, 351
+
+    Placoid scales, 48
+
+    Plagiostomata, 313
+
+    Plagiotremus, 498
+
+    Plagusia, 559
+
+    Plagyodus, 586
+
+    Plaice, 557
+
+    Pla-kat, 519
+
+    Platax, 448
+
+    Platinx, 656
+
+    Platycephalus, 477
+
+    Platycornus, 421
+
+    Platyglossus, 529
+
+    Platynematichthys, 566
+
+    Platypoecilus, 618
+
+    Platyptera, 489
+
+    Platyrhina, 342
+
+    Platysomidæ, 370
+
+    Platystethus, 450
+
+    Platystoma, 568
+
+    Platystomatichthys, 568
+
+    Platytroctes, 664
+
+    Playfair, 29
+
+    Plecoglossus, 646
+
+    Plecostomus, 576
+
+    Plectropoma, 382
+
+    Plesiops, 418
+
+    Pleurapophyses, 52
+
+    Pleurolepidæ, 366
+
+    Pleuronectes, 557
+
+    Pleuronectidæ, 553
+
+    Pleuropholis, 368
+
+    Plinthophorus, 666
+
+    Plionemus, 442
+
+    Plotosus, 563
+
+    Podabrus, 480
+
+    Podocys, 421
+
+    Poecilia, 617
+
+    Poeciloconger, 674
+
+    Poecilopsetta, 557
+
+    Poey, F., 31
+
+    Pogonias, 427
+
+    Poisonous fishes, 189
+
+    Poisson bleu, 650
+
+    Pollack, 541
+
+    Pollan, 649
+
+    Polyacanthus, 516
+
+    Polycaulus, 480
+
+    Polycentrus, 418
+
+    Polyipnus, 628
+
+    Polymixia, 423
+
+    Polynemus, 425
+
+    Polyodontidæ, 362
+
+    Polyprion, 382
+
+    Polypteroidei, 363
+
+    Polypterus, 364
+
+    Polyrhizodus, 330
+
+    Pomacanthus, 401
+
+    Pomacentrus, 525
+
+    Pomatomus, 395
+
+    Pomotis, 396
+
+    Pompilus, 444
+
+    Pope, 378
+
+    Porbeagle, 320
+
+    Porgy, 408
+
+    Porichthys, 468
+
+    Portheus, 500
+
+    Porthmeus, 446
+
+    Port Jackson Shark, 330
+
+    Porus abdominalis, 123
+
+    Porus genitalis, 123, 158
+
+    Postclavicula, 59, 92
+
+    Postfrontal bone, 57, 89
+
+    Post-pliocene fishes, 201
+
+    Post-temporal, 59, 92
+
+    Pout, 541
+
+    Powen, 649
+
+    Præoperculum, 38, 54, 90
+
+    Præorbital, 54
+
+    Prefrontal, 57, 89
+
+    Premaxillary, 53, 90
+
+    Premnas, 525
+
+    Preñadillas, 575
+
+    Pretympanic, 55
+
+    Priacanthus, 395
+
+    Pride, 693
+
+    Prionotus, 479
+
+    Prionurus, 440
+
+    Pristacanthus, 314
+
+    Pristidæ, 336
+
+    Pristigaster, 660
+
+    Pristiophorus, 335
+
+    Pristipoma, 385
+
+    Pristis, 337
+
+    Pristiurus, 326
+
+    Prochilodus, 607
+
+    Prooticum, 88
+
+    Propterus, 368
+
+    Propterygium, 70
+
+    Prosencephalon, 97
+
+    Prosopodasys, 417
+
+    Protamia, 372
+
+    Protocampus, 681
+
+    Protopterus, 356
+
+    Protosphyræna, 500
+
+    Prototroctes, 652
+
+    Prussian carp, 591
+
+    Psaliodus, 349
+
+    Psammobatis, 342
+
+    Psammodiscus, 557
+
+    Psammodus, 329
+
+    Psammoperca, 378
+
+    Psenes, 456
+
+    Psephurus, 363
+
+    Psettichthys, 556
+
+    Psettodes, 554
+
+    Psettus, 447
+
+    Pseudecheneis, 580
+
+    Pseudeutropius, 566
+
+    Pseudobagrus, 567
+
+    Pseudoberyx, 421
+
+    Pseudoblennius, 498
+
+    Pseudobranchiæ, 140
+
+    Pseudochalceus, 610
+
+    Pseudochilinus, 530
+
+    Pseudochromis, 466
+
+    Pseudodax, 530
+
+    Pseudoeleginus, 462
+
+    Pseudogobio, 596
+
+    Pseudojulis, 529
+
+    Pseudolabuca, 604
+
+    Pseudoperilampus, 601
+
+    Pseudophycis, 542
+
+    Pseudoplesiops, 466
+
+    Pseudorasbora, 596
+
+    Pseudorhombus, 556
+
+    Pseudoscarus, 532
+
+    Pseudosyngnathus, 680
+
+    Pseudovomer, 442
+
+    Pseudoxiphophorus, 617
+
+    Psilorhynchus, 604
+
+    Psychrolutes, 469
+
+    Pteraclis, 455
+
+    Pteragogus, 530
+
+    Pteraspis, 354
+
+    Pterichthys, 351
+
+    Pteroplatea, 344
+
+    Pteridium, 549
+
+    Pterois, 415
+
+    Pterophyllum, 537
+
+    Pteropsarion, 602
+
+    Pterygocephalus, 492
+
+    Pterygoid, 56
+
+    Pterygoplichthys, 576
+
+    Ptychacanthus, 314
+
+    Ptychobarbus, 595
+
+    Ptychodus, 330
+
+    Ptycholepis, 368
+
+    Ptyonotus, 480
+
+    Pycnodontidæ, 366
+
+    Pygopterus, 370
+
+    Pyloric appendages, 131
+
+    Pyrrhulina, 607
+
+
+    Quadrate Bone, 55, 89
+
+    Quoy et Gaimard, 26
+
+
+    Radius, 59
+
+    Raja, 340
+
+    Raniceps, 544
+
+    Rasbora, 597
+
+    Rasborichthys, 604
+
+    Rathke, 32
+
+    Ray, 8
+
+    Rays of fins, 40
+
+    Rays, 335, 341
+
+    Red bodies, 147
+
+    Red-dace, 599
+
+    Red-eye, 599
+
+    Red-fin, 599
+
+    Red-horse, 589
+
+    Red mullet, 404
+
+    Regalecus, 522
+
+    Reproduction of lost parts, 188
+
+    Reproduction, organs of, 157
+
+    Respiration, organs of, 135
+
+    Rete mirabile, 147
+
+    Retropinna, 647
+
+    Retzius, 32
+
+    Rhabdolepis, 370
+
+    Rhacolepis, 421
+
+    Rhadinichthys, 370
+
+    Rhamphichthys, 666
+
+    Rhamphocottus, 480
+
+    Rhamphosus, 507
+
+    Rhina, 334
+
+    Rhinelepis, 576
+
+    Rhinellus, 656
+
+    Rhinichthys, 596
+
+    Rhinobatus, 338
+
+    Rhinodon, 323
+
+    Rhinodoras, 572
+
+    Rhinoglanis, 573
+
+    Rhinonus, 549
+
+    Rhinoptera, 346
+
+    Rhizodus, 365
+
+    Rhodeus, 601
+
+    Rhomboidichthys, 556
+
+    Rhombosolea, 557
+
+    Rhombus, 555
+
+    Rhynchichthys, 424
+
+    Rhynchobatus, 337
+
+    Rhynchobdella, 498
+
+    Rhynchodus, 349
+
+    Rhypticus, 383
+
+    Rhytiodus, 608
+
+    Rib, 52
+
+    Ribbon-fishes, 520
+
+    Richardson, 27, 28
+
+    Risso, 17
+
+    Rita, 567
+
+    Rivulus, 615
+
+    Roach, 599, 600
+
+    Rock-cook, 528
+
+    Rockling, 544
+
+    Rohteichthys, 597
+
+    Rondelet, 5
+
+    Rosenthal, 32
+
+    Rough Dab, 555
+
+    Rudd, 599
+
+    Rüppell, 29
+
+    Russel, 16
+
+
+    Saccarius, 474
+
+    Saccobranchus, 565
+
+    Saccodon, 607
+
+    Saccopharynx, 670
+
+    Sælbling, 645
+
+    Sail-fish, 589
+
+    Sail-fluke, 555
+
+    Salanx, 650
+
+    Salarias, 494
+
+    Salivary glands, 124
+
+    Salminus, 611
+
+    Salmo, 631
+
+    Salmon, 644
+
+    Salmon-trout, 644
+
+    Salvelini, 645
+
+    Salviani, 5
+
+    Samaris, 556
+
+    Sand-eel, 550
+
+    Sand-piper, 693
+
+    Sandy Ray, 341
+
+    Sar, 406
+
+    Saragu, 406
+
+    Sarcodaces, 611
+
+    Sardine, 660
+
+    Sargina, 406
+
+    Sargo, 406
+
+    Sargodon, 405
+
+    Sargus, 406
+
+    Satanoperca, 537
+
+    Saurenchelys, 674
+
+    Saurichthys, 365
+
+    Saurida, 582
+
+    Sauridæ, 368
+
+    Saurocephalus, 500
+
+    Saurodipteridæ, 355
+
+    Saurodontidæ, 500
+
+    Saurorhamphus, 666
+
+    Saurus, 582
+
+    Saury, 620
+
+    Saw-fishes, 337
+
+    Scabbard-fish, 435
+
+    Scald-fish, 556
+
+    Scales, 45
+
+    Scaphaspis, 354
+
+    Scaphirhynchus, 362
+
+    Scapula, 59, 92
+
+    Scapular arch, 59
+
+    Scarichthys, 531
+
+    Scarus, 526, 530
+
+    Scatharus, 406
+
+    Scatophagus, 401
+
+    Schacra, 602
+
+    Schal, 573
+
+    Schedophilus, 455
+
+    Schell-fisch, 540
+
+    Schelly, 649
+
+    Schilbe, 566
+
+    Schilbichthys, 566
+
+    Schizopygopsis, 595
+
+    Schizothorax, 595
+
+    Schlegel, 29
+
+    Schneider, 15
+
+    Schultze, 33
+
+    Sciades, 568
+
+    Sciæna, 429
+
+    Sciænidæ, 426
+
+    Scissor, 610
+
+    Sclerodermi, 684
+
+    Sclerognathus, 589
+
+    Scolopsis, 389
+
+    Scomber, 457
+
+    Scombresox, 620
+
+    Scombridæ, 456
+
+    Scombroclupea, 656
+
+    Scombrops, 395
+
+    Scopelidæ, 582
+
+    Scopelosaurus, 587
+
+    Scopelus, 584
+
+    Scorpæna, 444
+
+    Scorpænichthys, 480
+
+    Scorpænidæ, 412
+
+    Scorpis, 402
+
+    Scup, 408
+
+    Scylliodus, 326
+
+    Scyllium, 325
+
+    Scymnus, 332
+
+    Sea-bat, 448
+
+    Sea-bream, 405, 408
+
+    Sea-cat, 493
+
+    Sea-devil, 344, 470
+
+    Sea-hedgehog, 687
+
+    Sea-horses, 682
+
+    Sea-perch, 381
+
+    Sea-serpents, 521
+
+    Sea-trout, 644
+
+    Sea-wolf, 493
+
+    Seba, 9
+
+    Sebastes, 413
+
+    Secondary sexual characters, 176
+
+    Seingo, 378
+
+    Selache, 322
+
+    Selachoidei, 314
+
+    Semicossyphus, 530
+
+    Semionotus, 368
+
+    Semiophorus, 441, 442
+
+    Semiplotus, 598
+
+    Seriola, 444
+
+    Seriolella, 444, 450
+
+    Seriolichthys, 444
+
+    Serranus, 381
+
+    Serrasalmo, 613
+
+    Setiform teeth, 126
+
+    Sewin, 644
+
+    Sexual characters, 176
+
+    Shad, 659
+
+    Shagreen, 315
+
+    Shagreen Skate, 341
+
+    Sharks, 314
+
+    Shark’s fins, 315
+
+    Sheep’s head, 406
+
+    Shiner, 599, 603
+
+    Shore-fishes, 257
+
+    Sicyases, 513
+
+    Sicydium, 487
+
+    Siebold, 28
+
+    Sillago, 464
+
+    Silondia, 566
+
+    Siluranodon, 566
+
+    Silurian fishes, 193
+
+    Silurichthys, 566
+
+    Siluridæ, 559
+
+    Siluris, 565
+
+    Siniperca, 376
+
+    Sinus rhomboidalis, 99
+
+    Siphagonus, 481
+
+    Siphonal stomach, 130
+
+    Siphonognathus, 533
+
+    Siphonostoma, 680
+
+    Sirembo, 549
+
+    Sirenidæ, 355
+
+    Sisor, 580
+
+    Skate, 341
+
+    Skeleton of--
+      Amia, 82
+      Amphioxus, 63
+      Chondropterygians, 66
+      Chondrostei, 74
+      Cyclostomes, 64
+      Dipnoi, 71
+      Ganoids, 71
+      Lepidosteus, 80
+      Polypterus, 77
+      Teleostei, 83
+
+    Skin, 45
+
+    Skip-jack, 447
+
+    Skipper, 620
+
+    Skull, 51, 85
+
+    Skulpin, 489
+
+    Smaris, 390
+
+    Smear-dab, 557
+
+    Smelt, 647
+
+    Smerdis, 375
+
+    Smiliogaster, 604
+
+    Snapper, 408
+
+    Snock, 437
+
+    Snout, 37
+
+    Solander, 13
+
+    Sole, 557
+
+    Solea, 557
+
+    Solenognathus, 682
+
+    Solenorhynchus, 678
+
+    Solenostoma, 678
+
+    Soleotalpa, 559
+
+    Sonnerat, 13
+
+    Soricidens, 405
+
+    Sorubim, 568
+
+    South Australian district, 283
+
+    Southern temperate zone, 281
+
+    Southern zone, 248
+
+    Spaniodon, 656
+
+    Sparidæ, 405
+
+    Sparnodus, 405
+
+    Sparoid scales, 46
+
+    Spathobatis, 338
+
+    Spathodactylus, 656
+
+    Spatularia, 362
+
+    Spawn-eater, 599
+
+    Spear-fish, 589
+
+    Sphærodon, 408
+
+    Sphærodontidæ, 368
+
+    Sphenacanthus, 314
+
+    Sphenocephalus, 421
+
+    Sphenodus, 319
+
+    Sphenoid, 57
+
+    Sphenoideum anterius, 89
+
+    Sphyræna, 499
+
+    Sphyrænodus, 500
+
+    Spiegel-Karpfen, 591
+
+    Spinacidæ, 330
+
+    Spinal chord, 96
+
+    Spinal column, 51
+
+    Spinax, 332
+
+    Spines of fins, 40
+
+    Spiracles, 138
+
+    Spiral valve, 128
+
+    Spirobranchus, 516
+
+    Splanchnoskeleton, 85
+
+    Spleen, 133
+
+    Splenial, 54, 91
+
+    Sprat, 659
+
+    Spratelloides, 662
+
+    Squaliobarbus, 602
+
+    Squaloraja, 335
+
+    Squamipinnes, 397
+
+    Squamosal, 88, 89
+
+    Stannius, 32, 33
+
+    Stare-gazer, 462
+
+    Starry Ray, 341
+
+    Stegophilus, 581
+
+    Stegostoma, 326
+
+    Steindachner, 28
+
+    Steller, 13
+
+    Stenostoma, 421
+
+    Sterlet, 361
+
+    Sternarchus, 666
+
+    Sternoptyx, 627
+
+    Sternopygus, 667
+
+    Stethojulis, 529
+
+    Stichæopsis, 498
+
+    Stichæus, 495
+
+    Sticharium, 498
+
+    Stickleback, 505
+
+    Stigmatophora, 681
+
+    Sting Rays, 342
+
+    Stock-fish, 540, 542
+
+    Stomach, 127
+
+    Stomias, 629
+
+    Stone-bass, 382
+
+    Stone-lugger, 596
+
+    Stone-roller, 589
+
+    Stone Toter, 596
+
+    Storer, 29
+
+    Strepsodus, 365
+
+    Strinsia, 541
+
+    Stromateus, 452
+
+    Strophodus, 330
+
+    Sturgeons, 361
+
+    Stygogenes, 575
+
+    Stylodontidæ, 368
+
+    Stylohyal, 58
+
+    Stylophorus, 522
+
+    Suboperculum, 38, 55, 91
+
+    Suborbital, 91
+
+    Sucker, 588
+
+    Sucking-fish, 460
+
+    Sudis, 586
+
+    Sun-fishes, 396, 454, 690
+
+    Supraclavicula, 59, 92
+
+    Supraoccipital, 56, 87
+
+    Supraorbital, 89
+
+    Suprascapula, 59
+
+    Supratemporal, 91
+
+    Surgeon, 439
+
+    Suspensorium of mandible, 55
+
+    Swammerdam, 7
+
+    Sword-fish, 431
+
+    Symbranchus, 669
+
+    Sympathic nerves, 108
+
+    Symphorus, 390
+
+    Symphysis, 54
+
+    Symphysodon, 537
+
+    Symplectic, 55, 89
+
+    Sympterygia, 342
+
+    Synagris, 390
+
+    Synanceia, 416
+
+    Synaphobranchus, 671
+
+    Synaptura, 558
+
+    Syngnathus, 680
+
+    Synodontis, 573
+
+
+    Taenianotus, 417
+
+    Taeniura, 343
+
+    Taractes, 454
+
+    Tasmanian sub-region, 248
+
+    Taste, organ of, 119
+
+    Taurinichthys, 526
+
+    Tautoga, 527
+
+    Teeth, 121, 124
+
+    Teleostei, 373
+
+    Telescope-fish, 592
+
+    Tellia, 615
+
+    Temera, 340
+
+    Temnodon, 446
+
+    Tenacity of life, 186
+
+    Tench, 600
+
+    Tephraeops, 406
+
+    Tephritis, 555
+
+    Tertiary fishes, 200
+
+    Testicles, 162, 167
+
+    Tetragonolepis, 368
+
+    Tetragonopterus, 609
+
+    Tetragonurus, 501
+
+    Tetranematichthys, 572
+
+    Tetraroge, 417
+
+    Tetrodon, 688
+
+    Teuthididæ, 418
+
+    Teuthis, 419
+
+    Thalassophryne, 468
+
+    Thalassorhinus, 319
+
+    Thaleichthys, 647
+
+    Thaumas, 334
+
+    Thectodus, 330
+
+    Therapon, 385
+
+    Tholichthys, 172
+
+    Thoracic fins, 42
+
+    Thornback, 341
+
+    Thrissonotus, 370
+
+    Thrissopater, 656
+
+    Thrissops, 371
+
+    Thunberg, 13
+
+    Thymallus, 649
+
+    Thynnichthys, 595
+
+    Thynnus, 457
+
+    Thyrsites, 436
+
+    Thysanopsetta, 556
+
+    Tiger-shark, 327
+
+    Tilurus, 180
+
+    Tinca, 599
+
+    Tongue, 124
+
+    Tope, 318
+
+    Top-knot, 555
+
+    Torgoch, 645
+
+    Torpedinidæ, 338
+
+    Torpedo, 339
+
+    Torsk, 546
+
+    Touch, organ of, 120
+
+    Toxabramis, 604
+
+    Toxotes, 403
+
+    Trachelochismus, 513
+
+    Trachelyopterus, 572
+
+    Trachichthys, 422
+
+    Trachinidæ, 462
+
+    Trachinops, 418
+
+    Trachinopsis, 462
+
+    Trachinus, 463
+
+    Trachurus, 442
+
+    Trachynotus, 447
+
+    Trachypterus, 522
+
+    Transverse line, 50
+
+    Triacanthodes, 684
+
+    Triacanthus, 684
+
+    Triacis, 319
+
+    Triænodon, 319
+
+    Triænophorichthys, 487
+
+    Triassic fishes, 197
+
+    Trichiurichthys, 434
+
+    Trichiuridæ, 433
+
+    Trichiurus, 436
+
+    Trichocyclus, 689
+
+    Trichodiodon, 689
+
+    Trichodon, 466
+
+    Trichogaster, 518
+
+    Trichomycterus, 581
+
+    Trichonotus, 490
+
+    Trichopleura, 417
+
+    Trifurcated Hake, 545
+
+    Trigla, 478
+
+    Triglops, 480
+
+    Trigorhina, 338
+
+    Triodon, 687
+
+    Tripterodon, 406
+
+    Tripterygium, 495
+
+    Tristichopterus, 365
+
+    Tristychius, 314
+
+    Trochocopus, 530
+
+    Tropical American region, 233
+
+    Trout, 644
+
+    Trubu, 660
+
+    Trumpeter, 412
+
+    Trumpet-fish, 509
+
+    Trunk, 39
+
+    Trygon, 343
+
+    Trygonidæ, 342
+
+    Trygonorhina, 338
+
+    Trypauchen, 489
+
+    Tunny, 458
+
+    Turbinal, 57, 91
+
+    Turbot, 555
+
+    Twaite Shad, 659
+
+    Tyellina, 326
+
+    Tylognathus, 596
+
+    Typhlichthys, 618
+
+    Typhlonus, 548
+
+
+    Uaru, 536
+
+    Ulna, 59
+
+    Umbra, 429, 619
+
+    Umbrina, 428
+
+    Umbrine, 429
+
+    Undina, 365
+
+    Upeneichthys, 404
+
+    Upeneoides, 404
+
+    Upeneus, 404
+
+    Upokororo, 652
+
+    Uraleptus, 543
+
+    Uranoscopus, 462
+
+    Urinary organs, 155
+
+    Urocampus, 681
+
+    Urocentrus, 498
+
+    Uroconger, 674
+
+    Urogymnus, 343
+
+    Urohyal, 58, 91
+
+    Urolophus, 343
+
+    Uronectes, 538
+
+    Uronemus, 360
+
+    Urosphen, 507
+
+    Urosthenes, 370
+
+    Useful fishes, 189
+
+
+    Vaillant, 31
+
+    Valenciennes, 18
+
+    Vandellia, 581
+
+    Velifer, 397
+
+    Vendace, 649
+
+    Ventral fins, 42
+
+    Vertebral column, 51
+
+    Vertical fins, 40
+
+    Villiform teeth, 126
+
+    Viviparous Blenny, 497
+
+    Vogt, 32
+
+    Vomer (bone), 56, 89
+
+    Vomer (gen.), 441
+
+    Vulsus, 489
+
+
+    Wallago, 566
+
+    Wardichthys, 370
+
+    Weever, 464
+
+    Wels, 565
+
+    Whiff, 555
+
+    White-bait, 658
+
+    White-fish, 599, 648
+
+    Whiting, 541
+
+    Whiting-pout, 541
+
+    Willughby, 8
+
+    Wrasses, 525
+
+
+    Xenocephalus, 553
+
+    Xenocharax, 612
+
+    Xenocypris, 598
+
+    Xenodermichthys, 664
+
+    Xenomystus, 576
+
+    Xenopterus, 688
+
+    Xiphias, 431
+
+    Xiphidion, 496
+
+    Xiphiidæ, 431
+
+    Xiphochilus, 530
+
+    Xiphopterus, 434
+
+    Xiphorhampus, 611
+
+    Xiphostoma, 611
+
+
+    Yarrell, 27
+
+    Yellow-tail, 444
+
+
+    Zanchus, 449
+
+    Zaniolepis, 491
+
+    Zärthe, 603
+
+    Zebra-Shark, 327
+
+    Zeus, 451
+
+    Zoarces, 497
+
+    Zope, 603
+
+    Zuzuki, 378
+
+    Zygaena, 318
+
+    Zygapophyses, 52
+
+    Zygobatis, 346
+
+
+                               THE END.
+
+
+               _Printed by_ R. & R. CLARK, _Edinburgh_.
+
+
+FOOTNOTES:
+
+[1] From ιχθυς, fish, and λογος, doctrine or treatise.
+
+[2] Down to this period the history of Ichthyology is fully treated in
+the first volume of Cuvier and Valenciennes “Hist. nat. d. Poiss.”
+
+[3] Description of Ceratodus. “Phil. Trans.,” 1871, ii.
+
+[4] In the formula generally preceding the description of a fish, “L.
+lat. 40,” would express that the scales between the head and caudal fin
+are arranged in 40 transverse series; and probably, that the lateral
+line is composed of the same number of scales. “L. transv. 8/5” would
+express that there are eight longitudinal series of scales between the
+median line of the back and the lateral line, and five between the
+lateral line and the middle of the abdomen.
+
+[5] Pterotic of Parker.
+
+[6] _C. Hasse_ has studied the modifications of the texture of the
+vertebræ and the structure of the Chondropterygian skeleton generally,
+and shown that they correspond in the main to the natural groups of
+the system, and, consequently, that they offer a valuable guide in the
+determination of fossil remains.
+
+[7] The Ganoids formed at former epochs the largest and most important
+order of fishes, many of the fossil forms being known from very
+imperfect remains only. It is quite possible that not a few of
+the latter, in which nothing whatever of the (probably very soft)
+endoskeleton has been preserved, should have to be assigned to some
+other order lower in the scale of organisation than the Ganoids (for
+instance, the _Cephalaspidæ_).
+
+[8] As first proposed by Huxley.
+
+[9] Stannius (pp. 60, 65) doubts the pure origin of these two bones
+from membranous tissue, and is inclined to consider them as “the
+extreme end of the abortive axial system.”
+
+[10] Parker’s nomenclature is adopted here.
+
+[11] According to _Langerhans_ “Untersuchungen über Petromyzon
+planeri” (Freiburg, 1873) an optic chiasma exists in that species.
+
+[12] This nerve is not shown in the figure of the brain of the Perch
+(Fig. 41), as reproduced above from Cuvier.
+
+[13] Müller considers a nerve rising jointly with the Vagus in
+Petromyzon to be this nerve (Fig. 45, _hy_).
+
+[14] On the development and structure of the dentition of _Scarina_,
+see _Boas_, “Die Zähne der Scaroiden,” in Zeitschr. f. Wiss. Zoolog.
+xxxii. (1878).
+
+[15] This applies to individuals only growing up under normal
+conditions. Dr. H. A. Meyer has made observations on young Herrings.
+Individuals living in the sea had attained at the end of the third
+month a length of 45 to 50 millimetres, whilst those reared from
+artificially-impregnated ova were only from 30 to 35 millimetres long.
+When the latter had been supplied with more abundant food, they grew
+proportionally more rapidly in the following months, so that at the end
+of the fifth month they had reached the same length as their brethren
+in the sea, viz. a length of 65 to 70 millimetres.
+
+[16] Ray Lankester considers it to be a portion of the long
+denticulated cornua of a genus _Eukeraspis_ allied to _Cephalaspis_.
+
+[17] Ekström, Fische in den Scheeren von Mörkö.
+
+[18] Will probably be found.
+
+[19] We distinguish these sub-regions, because their distinction is
+justified by other classes of animals; as regards freshwater fishes
+their distinctness is even less than that between Europe and Northern
+Asia.
+
+[20] Martens (Preuss. Exped. Ostas. Zool. i. p. 356), has already drawn
+attention that a Barbel, said to have been obtained by Ida Pfeiffer in
+Amboyna (Günth. Fish. vii. p. 123), cannot have come from that locality.
+
+[21] In the following and succeeding lists, those forms which are
+peculiar to and exclusively characteristic of, the region, are printed
+in italics; the other regions, in which the non-peculiar forms occur,
+are mentioned within brackets [].
+
+[22] Lates calcarifer in India as well as Australia.
+
+[23] One species (_Arius thalassinus_) found in Indian and African
+rivers.
+
+[24] This species extends from India into East Africa.
+
+[25] We have left out from these considerations the Ariina and
+Cyprinodonts, which can pass with impunity through salt water, and are
+spread over much larger areas.
+
+[26] Cope has discovered in a tertiary freshwater-deposit at Idaho
+an extinct genus of this group, _Diastichus_. He considers this
+interesting fact to be strongly suggestive of continuity of territory
+of Asia and North America.--“Proc. Am. Phil. Soc. 1873,” p. 55.
+
+[27] Leidy describes a Siluroid (_Pimelodus_) from tertiary
+deposits of Wyoming Territory. “Contrib. to the Extinct Vert. Fauna of
+the Western Territ. 1873,” p. 193.
+
+[28] The genera peculiar to the Equatorial zone are printed in italics.
+
+[29] Number of species uncertain.
+
+[30] See p. 151, Fig. 67.
+
+[31] See p. 128, Fig. 55.
+
+[32] See p. 104.
+
+[33] See p. 167, Figs. 79, 81.
+
+[34] See p. 136, Fig. 58.
+
+[35] See p. 167, Fig. 78.
+
+[36] The cartilaginous jaws of Sharks shrink at least a third in
+drying, and, therefore, cannot be kept at full stretch without tearing.
+
+[37] This exception is a Ray obtained during the “Challenger”
+expedition, and said to have been dredged in 565 fathoms.
+
+[38] See pp. 73 and 74, Figs. 35 and 36.
+
+[39] For other illustrations see p. 73, Fig. 35 (palatal view of head);
+p. 74, Fig. 36 (pectoral skeleton); p. 141, Fig. 60 (gills); p. 148,
+Fig. 65 (lung); p. 151, Fig. 67 (heart); p. 134, Fig. 57 (intestine);
+p. 165, Fig. 77 (ovary).
+
+[40] See p. 97, Fig. 41; and p. 152, Fig. 68.
+
+[41] The Acanthopterygians do not form a perfectly natural group,
+some heterogeneous elements being mixed up with it. Neither are the
+characters, by which it is circumscribed, absolutely distinctive.
+In some forms (certain Blennioids) the structure of the fins is
+almost the same as in Anacanths; there are some Acanthopterygians, as
+_Gerres_, _Pogonias_, which possess coalesced pharyngeals;
+and, finally, the presence or absence of a pneumatic duct loses much of
+its value as a taxonomic character when we consider that probably in
+all fishes a communication between pharynx and air-bladder exists at an
+early stage of development.
+
+[42] In this instance, one may entertain reasonable doubts as to the
+usefulness of the Pilot to the Shark.
+
+[43] Mackerel, like other marine fishes, birds, and mammals of prey,
+follow the shoals of young and adult Clupeoids in their periodical
+migrations; on the British coasts it is principally the fry of the
+Pilchard and Sprat which wanders from the open sea towards the coast,
+and guides the movements of the Mackerel.
+
+[44] The systematic affinities of these extinct genera are very
+obscure. Cope places them, with others (for instance _Protosphyræna_,
+which has a sword-like prolongation of the ethmoid), in a distinct
+family, _Saurodontidæ_: see “Vertebrata of the Cretaceous Formations of
+the West,” 1875.
+
+[45] For specific characters and detailed descriptions we refer to
+Günther, “Catal. of Fishes,” vol. vi.
+
+[46] The names “Bull-trout” and “Peal” are not attributable to definite
+species. We have examined specimens of _S. salar_, _S. trutta_, and
+_S. cambricus_ and _S. fario_, to which the name “Bull-trout” had been
+given; and that of “Peal” is given indiscriminately to Salmon-grilse
+and to _S. cambricus_.
+
+[47] Fig. 317 is taken from a specimen in which the horny covers of the
+dentition were lost, hence it does not represent accurately the shape
+of the teeth.
+
+[48] This name is two years older than _Amphioxus_.
+
+
+Transcriber’s Notes:
+
+1. Obvious printers’, punctuation and spelling errors have been
+corrected silently.
+
+2. Where hyphenation is in doubt, it has been retained as in the
+original.
+
+3. Some hyphenated and non-hyphenated versions of the same words have
+been retained as in the original.
+
+4. Superscripts are represented using the caret character, e.g. D^r. or
+X^{xx}.
+
+5. Italics are shown as _xxx_.
+
+6. Bold print is shown as =xxx=.
+
+
+
+*** END OF THE PROJECT GUTENBERG EBOOK AN INTRODUCTION TO THE STUDY OF FISHES ***
+\ No newline at end of file
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+      An Introduction to the Study of Fishes | Project Gutenberg
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+<body>
+<div style='text-align:center'>*** START OF THE PROJECT GUTENBERG EBOOK AN INTRODUCTION TO THE STUDY OF FISHES ***</div>
+
+<h1><span class="smaller">AN INTRODUCTION</span><br>
+
+<span class="xs">TO THE</span><br>
+
+<span class="gesperrt">STUDY OF FISHES</span></h1>
+
+
+<p class="center xs p4">BY</p>
+
+<p class="center">ALBERT C. L. G. GÜNTHER</p>
+
+<p class="center sm">M.A. M.D. Ph.D. F.R.S.</p>
+
+<p class="center xs">KEEPER OF THE ZOOLOGICAL DEPARTMENT IN THE BRITISH MUSEUM</p>
+
+  <div class="figcenter">
+     <img
+    class="p2"   
+    src="images/a0030.jpg"
+     alt="">
+     <p class="p0 center smaller">Carpit aquas pinnis.</p>
+  </div>
+
+<p class="center p2 sm">EDINBURGH<br>
+ADAM AND CHARLES BLACK<br>
+1880</p>
+
+<p class="center p4 xs">[<i>All rights reserved.</i>]</p>
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_v">[v]</span></p>
+
+<p class="p6 xs center"><i>Printed by</i> <span class="smcap">R. &amp; R. Clark</span>, <i>Edinburgh</i>.</p>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<h2>PREFACE.</h2>
+</div>
+
+  <div class="figcenter">
+    <img
+    class="p0" 
+    src="images/a003_deco.jpg"
+    alt="">
+  </div>
+
+<p>The scope of the present work is to give in a concise form an account
+of the principal facts relating to the structure, classification, and
+life-history of Fishes. It is intended to meet the requirements of
+those who are desirous of studying the elements of Ichthyology; to
+serve as a book of reference to zoologists generally; and, finally,
+to supply those who, like travellers, have frequent opportunities
+of observing fishes, with a ready means of obtaining information.
+The article on “Ichthyology,” prepared by the late Sir J. Richardson
+for the eighth edition of the “Encyclopædia Britannica,” is the only
+publication which has hitherto partly satisfied such requirements;
+and when I undertook, some years ago, to revise, or rather rewrite
+that article for the new edition of that work, it occurred to me that
+I might at the same time prepare a Handbook of Ichthyology, whilst
+reserving for the article an abstract so condensed as to be adapted for
+the wants of the general reader.</p>
+
+<p>From the general plan of the work I have only departed in those
+chapters which deal with the Geographical Distribution of Fishes. This
+is a subject which has never before been treated in a general<span class="pagenum" id="Page_vi">[vi]</span> and
+comprehensive manner, and seemed to demand particular attention. I
+have, therefore, thought it right to give nominal lists of the Faunæ,
+and the other details of fact on which I have based my conclusions,
+although all the necessary materials may be found in my “Catalogue of
+Fishes.”</p>
+
+<p>A few references only to the numerous sources which were consulted
+on the subjects of Chapters 1–12, are inserted in the text; more not
+required by the beginner; he is introduced to a merely elementary
+knowledge of facts well known to the advanced student.</p>
+
+<p>With regard to the illustrations, about twenty have been prepared after
+originals published by Cuvier, J. Müller, Owen, Traquair, Duméril,
+Cunningham, Hasse, Poey, Siebold, and Gegenbaur. A similar number,
+representing extinct fishes, have been taken, with the kind permission
+of the author, from Owen’s “Palæontology.” My best thanks are due also
+to the Committee of Publications of the Zoological Society, and to the
+Editors of the “Annals and Magazine of Natural History,” and of the
+“Journal des Museum Godeffroy,” for the loan of woodcuts illustrating
+some of my papers on South American fishes and on larval forms. The
+remainder of the illustrations (about three-fourths) are either
+original figures, or formed part of the article on ‘Ichthyology’ in the
+former edition of the “Encyclopædia Britannica.”</p>
+
+<p class="sm"><span class="smcap">London</span>, <i>3d October 1880</i>.</p>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_vii">[vii]</span></p>
+
+<h2>CONTENTS.</h2>
+</div>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <th class="header" colspan="2">INTRODUCTORY REMARKS.</th>
+  </tr>
+
+  <tr>
+    <th></th>
+    <th class="pag">PAGE</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Fish defined—Ichthyology defined</td>
+    <td class="pag"><a href="#Page_1">1</a></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER I.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">History and Literature</td>
+    <td class="pag"><a href="#Page_2">2</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Aristotle, <a href="#Page_2">2</a>—Belon, <a href="#Page_4">4</a>—Salviani, <a href="#Page_6">6</a>—Rondelet, <a href="#Page_6">6</a>—Faunists and
+Anatomists of the Seventeenth Century, <a href="#Page_7">7</a>—Ray and Willughby,
+<a href="#Page_8">8</a>—Artedi, <a href="#Page_9">9</a>—Linnæus, <a href="#Page_10">10</a>—Gronow and Klein, <a href="#Page_12">12</a>—Pupils
+and Successors of Linnæus, <a href="#Page_12">12</a>—Bloch, <a href="#Page_13">13</a>—Lacépède, <a href="#Page_15">15</a>—Anatomists
+and Faunists preceding Cuvier, <a href="#Page_16">16</a>—Cuvier, <a href="#Page_17">17</a>—Agassiz,
+<a href="#Page_20">20</a>—J. Müller, <a href="#Page_22">22</a>—Discovery of Ceratodus, <a href="#Page_25">25</a>—Recent
+publications on Fishes, <a href="#Page_26">26</a>—Latest systematic works, <a href="#Page_33">33</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER II.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Topographical description of the External Parts of Fishes</td>
+    <td class="pag"><a href="#Page_35">35</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Form of the body, <a href="#Page_35">35</a>—External parts of the head, <a href="#Page_36">36</a>—Trunk and
+Tail, <a href="#Page_39">39</a>—Fins; their structure, position, and function, <a href="#Page_40">40</a>—Skin
+and Scales, <a href="#Page_45">45</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER III.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Terminology and Topography of the Skeleton</td>
+    <td class="pag"><a href="#Page_51">51</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Axial portion, <a href="#Page_51">51</a>—Vertebra and its parts; terms defined, <a href="#Page_51">51</a>—Skull;
+bones topographically enumerated, <a href="#Page_53">53</a>—Bones of the
+limbs, <a href="#Page_59">59</a>—Synonymic list of bones, <a href="#Page_59">59</a>.</td>
+    <td><span class="pagenum" id="Page_viii">[viii]</span></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER IV.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Modifications of the Skeleton</td>
+    <td class="pag"><a href="#Page_63">63</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Branchiostoma, <a href="#Page_63">63</a>—Cyclostomes, <a href="#Page_64">64</a>—Chondropterygians, <a href="#Page_66">66</a>—Holocephali,
+<a href="#Page_70">70</a>—Ganoids, <a href="#Page_71">71</a>—Dipnoi, <a href="#Page_71">71</a>—Chondrostei, <a href="#Page_74">74</a>—Polypteroidei,
+<a href="#Page_77">77</a>—Lepidosteoidei, <a href="#Page_80">80</a>—Amioidei, <a href="#Page_82">82</a>—Teleostei,
+<a href="#Page_83">83</a>—Classification of the bones of the Teleosteous skull according
+to the vertebral doctrine, <a href="#Page_85">85</a>—their morphological classification,
+<a href="#Page_86">86</a>—Limb-bones of Teleosteans, <a href="#Page_92">92</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER V.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Myology</td>
+    <td class="pag"><a href="#Page_93">93</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">General arrangement of the Muscles, <a href="#Page_93">93</a>—Electric organs, <a href="#Page_94">94</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER VI.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Neurology</td>
+    <td class="pag"><a href="#Page_96">96</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Of Branchiostoma, <a href="#Page_96">96</a>—Spinal chord, <a href="#Page_96">96</a>—Brain, its size, <a href="#Page_97">97</a>—Brain
+of Osseous fishes, <a href="#Page_97">97</a>—of Ganoids, <a href="#Page_98">98</a>—of Chondropterygians,
+<a href="#Page_100">100</a>—of Cyclostomes, <a href="#Page_101">101</a>—Spino-cerebral nerves, <a href="#Page_103">103</a>—Spinal
+nerves, <a href="#Page_107">107</a>—Sympathic system, <a href="#Page_108">108</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER VII.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">The Organs of Sense</td>
+    <td class="pag"><a href="#Page_109">109</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Smell, <a href="#Page_109">109</a>—Sight, <a href="#Page_111">111</a>—Hearing; connection of the ear with the
+air-bladder, <a href="#Page_116">116</a>—Taste, <a href="#Page_119">119</a>—Touch, <a href="#Page_120">120</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER VIII.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">The Organs of Nutrition and Digestion</td>
+    <td class="pag"><a href="#Page_121">121</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Food and mode of feeding, <a href="#Page_121">121</a>—Buccal and abdominal cavities and
+their openings, <a href="#Page_123">123</a>—Mouth and tongue, <a href="#Page_123">123</a>—Forms, texture,
+and arrangement of teeth, <a href="#Page_124">124</a>—Intestinal tract, <a href="#Page_127">127</a>—Liver,
+<a href="#Page_132">132</a>—Pancreas, <a href="#Page_133">133</a>—Spleen, <a href="#Page_133">133</a>.</td>
+    <td><span class="pagenum" id="Page_ix">[ix]</span></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER IX.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Organs of Respiration</td>
+    <td class="pag"><a href="#Page_135">135</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Respiration, <a href="#Page_135">135</a>—Structure and arrangement of the gills, <a href="#Page_136">136</a>—Pseudobranchiæ,
+<a href="#Page_141">140</a>—Accessory respiratory organs, <a href="#Page_142">142</a>—Air-bladder;
+its varieties, structure, and functions, <a href="#Page_142">142</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER X.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Organs of Circulation</td>
+    <td class="pag"><a href="#Page_150">150</a></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XI.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Urinary Organs</td>
+    <td class="pag"><a href="#Page_155">155</a></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XII.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Organs of Reproduction</td>
+    <td class="pag"><a href="#Page_157">157</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Fishes are dioecious, <a href="#Page_157">157</a>—Hermaphroditism, <a href="#Page_157">157</a>—Oviparous and
+viviparous fishes, <a href="#Page_157">157</a>—Generative organs of Branchiostoma,
+<a href="#Page_157">157</a>—of Cyclostomes; their ova, <a href="#Page_158">158</a>—Female organs of
+Teleosteans and their ova, <a href="#Page_158">158</a>—Instances of females taking
+care of their progeny, <a href="#Page_160">160</a>—Male organs of Teleosteans, <a href="#Page_162">162</a>—Instances
+of males taking care of their progeny, 163—Generative
+organs of Ganoids, <a href="#Page_163">163</a>—of Chondropterygians and their
+ova, <a href="#Page_166">166</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XIII.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Growth and Variation of Fishes</td>
+    <td class="pag"><a href="#Page_170">170</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Changes of form of the body or certain parts, normally accompanying
+growth, <a href="#Page_170">170</a>—Changes dependent on sexual development,
+<a href="#Page_176">176</a>—Secondary sexual differences, <a href="#Page_176">176</a>—Mixogamous, polygamous,
+and monogamous fishes, <a href="#Page_177">177</a>—Hybridism as a cause
+of variation, <a href="#Page_178">178</a>—Regular and irregular growth of fishes, <a href="#Page_178">178</a>—Leptocephali
+not a normal state of development, <a href="#Page_179">179</a>—Changes
+of colour of the muscles and external parts; chromatophors,
+<a href="#Page_182">182</a>—Albinism, <a href="#Page_183">183</a>.</td>
+    <td><span class="pagenum" id="Page_x">[x]</span></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XIV.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Domesticated and Acclimatised Fishes, etc.</td>
+    <td class="pag"><a href="#Page_185">185</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Domesticated fishes, <a href="#Page_185">185</a>—Acclimatisation of fishes, <a href="#Page_185">185</a>—Artificial
+impregnation of ova, <a href="#Page_186">186</a>—Tenacity of life, <a href="#Page_186">186</a>—Reproduction
+of lost parts, <a href="#Page_188">188</a>—Hybernation, <a href="#Page_188">188</a>—Useful fishes, <a href="#Page_189">189</a>—Poisonous
+fishes, <a href="#Page_189">189</a>—Poison-organs, <a href="#Page_190">190</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XV.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Distribution of Fishes in time</td>
+    <td class="pag"><a href="#Page_193">193</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Oldest fish-remains, <a href="#Page_193">193</a>—Devonian fishes, <a href="#Page_194">194</a>—Carboniferous,
+<a href="#Page_196">196</a>—Permian, <a href="#Page_197">197</a>—Triassic, <a href="#Page_197">197</a>—Liassic, <a href="#Page_198">198</a>—Oolitic, <a href="#Page_199">199</a>—Cretaceous,
+<a href="#Page_199">199</a>—Tertiary, <a href="#Page_20">200</a>—Post-pliocene, <a href="#Page_201">201</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XVI.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">The Distribution of existing Fishes over the
+Earth’s Surface.—General Remarks</td>
+    <td class="pag"><a href="#Page_202">202</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Freshwater-, Marine-, and Brackish-water Fishes, <a href="#Page_202">202</a>—Changes of
+the habitat of numerous fishes, active, <a href="#Page_203">203</a>—or dependent on
+geological changes, <a href="#Page_204">204</a>—Agencies operating upon the distribution
+of Freshwater and Marine fishes, <a href="#Page_205">205</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XVII.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">The Distribution of Freshwater Fishes</td>
+    <td class="pag"><a href="#Page_208">208</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">List of Freshwater Fishes, <a href="#Page_208">208</a>—Continuous and interrupted range
+of distribution, <a href="#Page_209">209</a>—The ways of dispersal of Freshwater
+fishes, <a href="#Page_211">211</a>—A wide range of a type is not necessarily proof of
+its antiquity, <a href="#Page_212">212</a>—Each fauna is composed of ancient, autochthont,
+and immigrant species, <a href="#Page_213">213</a>—Division of the globe
+into zoological regions; freshwater fishes have been spread in
+circumpolar zones, <a href="#Page_215">215</a>—Cyprinidæ and Siluridæ, most important
+families in recognising the zoo-geographical regions,
+<a href="#Page_216">216</a>—Division of the faunæ of Freshwater fishes, <a href="#Page_217">217</a>—I.
+<i>Equatorial Zone</i>, <a href="#Page_218">218</a>—Indian Region, <a href="#Page_220">220</a>—African Region,
+<a href="#Page_227">227</a>—Tropical American or Neotropical Region, <a href="#Page_233">233</a>—Tropical
+Pacific Region, <a href="#Page_238">238</a>—II. <i>Northern Zone</i>, <a href="#Page_240">240</a>—Europe-Asiatic
+or Palæarctic Region, <a href="#Page_243">243</a>—North American or Nearctic
+Region, <a href="#Page_246">246</a>—III. <i>Southern Zone</i>, with Tasmanian, New
+Zealand, and Fuegian Sub-regions, <a href="#Page_248">248</a>.</td>
+    <td><span class="pagenum" id="Page_xi">[xi]</span></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XVIII.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">The Fishes of the Brackish Water</td>
+    <td class="pag"><a href="#Page_251">251</a></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XIX.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">The Distribution of Marine Fishes</td>
+    <td class="pag"><a href="#Page_255">255</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Shore-fishes, Pelagic, and Deep-sea fishes, <a href="#Page_255">255</a>—List of Shore-fishes,
+<a href="#Page_257">257</a>—Oceanic areæ as determined by Shore-fishes, <a href="#Page_259">259</a>—Distribution
+of Shore-fishes compared with that of Freshwater-fishes,
+<a href="#Page_260">260</a>—I. <i>Arctic Ocean</i>, <a href="#Page_261">261</a>—II. <i>Northern Temperate Zone</i>, <a href="#Page_262">262</a>—Temperate
+North-Atlantic, <a href="#Page_262">262</a>—with British, <a href="#Page_263">263</a>—Mediterranean,
+<a href="#Page_264">264</a>—and North American districts, <a href="#Page_266">266</a>—Temperate
+North-Pacific, <a href="#Page_268">268</a>—with Kamtschatkan, <a href="#Page_269">269</a>—Japanese, <a href="#Page_270">270</a>—and
+Californian districts, <a href="#Page_271">271</a>—III. <i>Equatorial Zone</i>, <a href="#Page_272">272</a>—with
+Tropical Atlantic, <a href="#Page_278">278</a>—Indo-Pacific Ocean, <a href="#Page_278">278</a>—and
+the Pacific Coasts of Tropical America, <a href="#Page_279">279</a>—IV. <i>Southern</i>
+<i>Temperate Zone</i>, <a href="#Page_281">281</a>—with the Cape of Good Hope, <a href="#Page_283">283</a>—South
+Australia and New Zealand, <a href="#Page_283">283</a>—Chile, <a href="#Page_288">288</a>—and
+Patagonia, <a href="#Page_289">289</a>—V. <i>Antarctic Ocean</i>, <a href="#Page_289">289</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XX.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">Distribution of Pelagic Fishes</td>
+    <td class="pag"><a href="#Page_292">292</a></td>
+  </tr>
+
+  <tr>
+    <th class="header" colspan="2">CHAPTER XXI.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1">The Fishes of the Deep Sea</td>
+    <td class="pag"><a href="#Page_296">296</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2">Deep-sea fishes a recent discovery, <a href="#Page_296">296</a>—Physical conditions affecting
+these fishes, <a href="#Page_297">297</a>—Characteristics of Deep-sea fishes, <a href="#Page_299">299</a>—Their
+vertical and horizontal distribution, <a href="#Page_304">304</a>—List of Deep-sea
+fishes, <a href="#Page_305">305</a>.</td>
+    <td><span class="pagenum" id="Page_xii">[xii]</span></td>
+  </tr>
+
+</table>
+
+<h2>SYSTEMATIC AND DESCRIPTIVE PART.</h2>
+
+<table class="smaller" style="max-width: 50em">
+
+  <tr>
+    <th class="header1 smcap" colspan="3">First Sub-class—Palæichthyes.</th>
+  </tr>
+
+  <tr>
+    <th></th>
+    <th></th>
+    <th class="pag">PAGE</th>
+  </tr>
+
+  <tr>
+    <td class="cht1" colspan="2">First Order—Chondropterygii</td>
+    <td class="pag"><a href="#Page_313">313</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn">I.</td>
+    <td class="cht2"><i>Plagiostomata</i></td>
+    <td><a href="#Page_313">313</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">A. <i>Selachoidei—Sharks</i></td>
+    <td><a href="#Page_314">314</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Carchariidæ (Blue Shark, Tope, Hammerhead,
+Hound), <a href="#Page_316">316</a>—Lamnidæ (Porbeagle, Carcharodon,
+Fox-Shark, Basking-Shark), <a href="#Page_319">319</a>—Rhinodontidæ,
+<a href="#Page_323">323</a>—Notidanidæ, <a href="#Page_324">324</a>—Scylliidæ (Dog-fishes), <a href="#Page_325">325</a>—
+Hybodontidæ, <a href="#Page_328">328</a>—Cestraciontidæ (Port Jackson
+Shark), <a href="#Page_328">328</a>—Spinacidæ (Spiny Dogs, Greenland
+Shark), <a href="#Page_330">330</a>—Rhinidæ, <a href="#Page_334">334</a>—Pristiophoridæ, <a href="#Page_335">335</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">B. <i>Batoidei—Rays</i></td>
+    <td><a href="#Page_335">335</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Pristidæ (Saw-fishes), <a href="#Page_336">336</a>—Rhinobatidæ, <a href="#Page_337">337</a>—Torpedinidæ
+(Electric Rays), <a href="#Page_338">338</a>—Rajidæ (Rays
+and Skates), <a href="#Page_340">340</a>—Trygonidæ (Sting Rays), <a href="#Page_342">342</a>—Myliobatidæ
+(Eagle Rays), <a href="#Page_344">344</a>.</td>
+    <td></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">II.</td>
+    <td class="cht2"><i>Holocephala</i></td>
+    <td><a href="#Page_348">348</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Chimæridæ, <a href="#Page_348">348</a>.</td>
+    <td></td>
+  </tr>
+ 
+  <tr>
+    <td class="cht1 smcap" colspan="2">Second Order—Ganoidei</td>
+    <td><a href="#Page_350">350</a></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">I.</td>
+    <td class="cht3"><i>Placodermi</i></td>
+    <td><a href="#Page_351">351</a></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">II.</td>
+    <td class="cht3"><i>Acanthodini</i></td>
+    <td><a href="#Page_355">355</a></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">III.</td>
+    <td class="cht3"><i>Dipnoi</i></td>
+    <td><a href="#Page_355">355</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Sirenidæ (Lepidosiren, Protopterus, Ceratodus),
+<a href="#Page_355">355</a>—Ctenododipteridæ, <a href="#Page_359">359</a>—Phaneropleuridæ, <a href="#Page_360">360</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">IV.</td>
+    <td class="cht3"><i>Chondrostei</i></td>
+    <td><a href="#Page_360">360</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Acipenseridæ (Sturgeons), <a href="#Page_360">360</a>—Polyodontidæ, <a href="#Page_362">362</a>.</td>
+    <td><span class="pagenum" id="Page_xiii">[xiii]</span></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">V.</td>
+    <td class="cht3"><i>Polypteroidei</i></td>
+    <td><a href="#Page_363">363</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Polypteridæ, <a href="#Page_364">364</a>—Saurodipteridæ, <a href="#Page_365">365</a>—Coelacanthidæ,
+<a href="#Page_365">365</a>—Holoptychidæ, <a href="#Page_365">365</a>.</td>
+    <td></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">VI.</td>
+    <td class="cht3"><i>Pycnodontoidei</i></td>
+    <td><a href="#Page_366">366</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Pleurolepidæ, <a href="#Page_366">366</a>—Pycnodontidæ, <a href="#Page_366">366</a>.</td>
+    <td></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">VII.</td>
+    <td class="cht3"><i>Lepidosteoidei</i></td>
+    <td><a href="#Page_367">367</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Lepidosteidæ, 367—Sauridæ, 368—Stylodontidæ,
+368—Sphærodontidæ, 368—Aspidorhynchidæ,
+369—Palæoniscidæ, 369—Platysomidæ, 370.</td>
+    <td></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">VIII.</td>
+    <td class="cht3"><i>Amioidei</i></td>
+    <td><a href="#Page_370">370</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Caturidæ, <a href="#Page_371">371</a>—Leptolepidæ, <a href="#Page_371">371</a>—Amiidæ
+(Bow-fin), <a href="#Page_371">371</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header1 smcap" colspan="3">Second Sub-class—Teleostei.</th>
+  </tr>
+
+  <tr>
+    <td class="cht1 smcap" colspan="2">First Order—Acanthopterygii</td>
+    <td class="pag"><a href="#Page_374">374</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn">I.</td>
+    <td class="cht3"><i>A. perciformes</i></td>
+    <td><a href="#Page_374">374</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Percidæ (Freshwater-Perches, Bass, Sea-Perches,
+Centrarchus), <a href="#Page_375">375</a>—Squamipinnes (Coral-Fishes),
+<a href="#Page_397">397</a>—Mullidæ (Red-Mullets), <a href="#Page_403">403</a>—Sparidæ
+(Sea-breams), <a href="#Page_405">405</a>—Hoplognathidæ, <a href="#Page_410">410</a>—Cirrhitidæ,
+<a href="#Page_410">410</a>—Scorpænidæ, <a href="#Page_412">412</a>—Nandidæ, <a href="#Page_418">418</a>—Polycentridæ,
+<a href="#Page_418">418</a>—Teuthididæ, <a href="#Page_418">418</a>.</td>
+    <td></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">II.</td>
+    <td class="cht3"><i>A. beryciformes</i></td>
+    <td><a href="#Page_419">419</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Berycidæ, <a href="#Page_420">420</a>.</td>
+    <td></td>
+  </tr>
+ 
+  <tr>
+    <td class="chn">III.</td>
+    <td class="cht3"><i>A. kurtiformes</i></td>
+    <td><a href="#Page_424">424</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Kurtidæ, <a href="#Page_424">424</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">IV.</td>
+    <td class="cht3"><i>A. polynemiformes</i></td>
+    <td><a href="#Page_425">425</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Polynemidæ, <a href="#Page_425">425</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">V.</td>
+    <td class="cht3"><i>A. sciæniformes</i></td>
+    <td><a href="#Page_426">426</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Sciænidæ (Meagres), <a href="#Page_426">426</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">VI.</td>
+    <td class="cht3"><i>A. xiphiiformes</i></td>
+    <td><a href="#Page_431">431</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Xiphiidæ (Sword-fishes), <a href="#Page_431">431</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">VII.</td>
+    <td class="cht3"><i>A. trichiuriformes</i></td>
+    <td><a href="#Page_433">433</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Trichiuridæ (Scabbard-fishes, Hairtails), <a href="#Page_433">433</a>—Palæorhynchidæ, <a href="#Page_437">437</a>.</td>
+    <td><span class="pagenum" id="Page_xiv">[xiv]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chn">VIII.</td>
+    <td class="cht3"><i>A. cotto-scombriformes</i></td>
+    <td><a href="#Page_438">438</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Acronuridæ (Surgeons), <a href="#Page_438">438</a>—Carangidæ
+(Horse-Mackerels, Pilot-fish, Boar-fish), <a href="#Page_440">440</a>—Cyttidæ
+(John Dorey), <a href="#Page_450">450</a>—Stromateidæ, <a href="#Page_452">452</a>—Coryphænidæ
+(Dolphin, Sun-fish), <a href="#Page_452">452</a>—Nomeidæ,
+<a href="#Page_455">455</a>—Scombridæ (Mackerel, Tunny, Bonito, Albacore,
+Sucking-fish), <a href="#Page_456">456</a>—Trachinidæ (Stare-gazer,
+Weever, etc.), <a href="#Page_462">462</a>—Malacanthidæ, <a href="#Page_467">467</a>—Batrachidæ,
+<a href="#Page_467">467</a>—Psychrolutidæ, <a href="#Page_469">469</a>—Pediculati (Angler,
+Antennarius, etc.), <a href="#Page_49">469</a>—Cottidæ (Bull-heads, Gurnards),
+<a href="#Page_476">476</a>—Cataphracti (Flying Gurnards), <a href="#Page_480">480</a>—Pegasidæ, <a href="#Page_482">482</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">IX.</td>
+    <td class="cht3"><i>A. gobiiformes</i></td>
+    <td><a href="#Page_483">483</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Discoboli (Lump-suckers), <a href="#Page_483">483</a>—Gobiidæ
+(Gobies, Dragonets), <a href="#Page_485">485</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">X.</td>
+    <td class="cht3"><i>A. blenniiformes</i></td>
+    <td><a href="#Page_490">490</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Cepolidæ (Band-fishes), <a href="#Page_490">490</a>—Trichonotidæ,
+<a href="#Page_490">490</a>—Heterolepidotidæ, <a href="#Page_491">491</a>—Blenniidæ (Wolf-fish,
+Blennies), <a href="#Page_492">492</a>—Acanthoclinidæ, <a href="#Page_498">498</a>—Mastacembelidæ, <a href="#Page_499">499</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XI.</td>
+    <td class="cht3"><i>A. mugiliformes</i></td>
+    <td><a href="#Page_499">499</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Sphyrænidæ (Barracudas), <a href="#Page_499">499</a>—Atherinidæ
+(Atherines), <a href="#Page_500">500</a>—Mugilidæ (Mullets), <a href="#Page_501">501</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XII.</td>
+    <td class="cht3"><i>A. gastrosteiformes</i></td>
+    <td><a href="#Page_504">504</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Gastrosteidæ (Sticklebacks), <a href="#Page_504">504</a>—Fistulariidæ
+(Flute-mouths), <a href="#Page_507">507</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XIII.</td>
+    <td class="cht3"><i>A. centrisciformes</i></td>
+    <td><a href="#Page_508">508</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Centriscidæ, <a href="#Page_508">508</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XIV.</td>
+    <td class="cht3"><i>A. gobiesociformes</i></td>
+    <td><a href="#Page_510">510</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Gobiesocidæ, <a href="#Page_512">512</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XV.</td>
+    <td class="cht3"><i>A. channiformes</i></td>
+    <td><a href="#Page_513">513</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Ophiocephalidæ, <a href="#Page_513">513</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XVI.</td>
+    <td class="cht3"><i>A. labyrinthibranchii</i></td>
+    <td><a href="#Page_514">514</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Labyrinthici (Climbing Perch, Gourami),
+<a href="#Page_514">514</a>—Luciocephalidæ, <a href="#Page_519">519</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XVII.</td>
+    <td class="cht3"><i>A. lophotiformes</i></td>
+    <td><a href="#Page_519">519</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Lophotidæ, <a href="#Page_519">519</a>.</td>
+    <td><span class="pagenum" id="Page_xv">[xv]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XVIII.</td>
+    <td class="cht3"><i>A. tæniiformes</i></td>
+    <td><a href="#Page_520">520</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Trachypteridæ (Ribbon-fishes), <a href="#Page_520">520</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">XIX.</td>
+    <td class="cht3"><i>A. notacanthiformes</i></td>
+    <td><a href="#Page_523">523</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Notacanthidæ, <a href="#Page_523">523</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="cht1 smcap" colspan="2">Second Order—Acanthopterygii Pharyngognathi</td>
+    <td class="pag"><a href="#Page_523">523</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Pomacentridæ (Coral-fishes), <a href="#Page_524">524</a>—Labridæ
+(Wrasses, Parrot-wrasses), <a href="#Page_525">525</a>—Embiotocidæ, <a href="#Page_533">533</a>—Chromides,
+<a href="#Page_534">534</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="cht1 smcap" colspan="2">Third Order—Anacanthini</td>
+    <td class="pag"><a href="#Page_537">537</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn">I.</td>
+    <td class="cht3"><i>A. gadoidei</i></td>
+    <td><a href="#Page_537">537</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Families: Lycodidæ, 537—Gadidæ (Cod-fishes, Hake,
+Burbot, Ling, Rockling, Torsk), 539—Ophidiidæ
+(Brotula, Fierasfer, Sand-eel, Congrogadus), 546—Macruridæ,
+551.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">II.</td>
+    <td class="cht3"><i>A. pleuronectoidei</i></td>
+    <td><a href="#Page_553">553</a></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht4">Family: Pleuronectidæ (Flat-fishes), <a href="#Page_553">553</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="cht1 smcap" colspan="2">Fourth Order—Physostomi</td>
+    <td class="pag"><a href="#Page_559">559</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families: <i>Siluridæ</i>; their skeleton, <a href="#Page_559">559</a>—divided into eight subdivisions
+and sixteen groups; Clariina, <a href="#Page_563">563</a>—Plotosina, 563—Silurina,
+<a href="#Page_565">565</a>—Hypophthalmina, <a href="#Page_566">566</a>—Bagrina, <a href="#Page_567">567</a>—Amiurina,
+<a href="#Page_567">567</a>—Pimelodina, <a href="#Page_568">568</a>—Ariina, <a href="#Page_569">569</a>—Doradina, <a href="#Page_572">572</a>—Rhinoglanina,
+<a href="#Page_573">573</a>—Malapterurina (Electric Catfish), <a href="#Page_574">574</a>—Hypostomatina
+(Preñadillas, Loricaria, etc.), <a href="#Page_575">575</a>—Aspredinina,
+<a href="#Page_580">580</a>—Nematogenyina and Trichomycterina, <a href="#Page_581">581</a>—Stegopholina,
+<a href="#Page_581">581</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families of Physostomi continued: Scopelidæ, <a href="#Page_582">582</a>—<i>Cyprinidæ</i>
+(Carps), <a href="#Page_587">587</a>—divided into fourteen groups, viz. Catostomina
+(Suckers), <a href="#Page_588">588</a>—Cyprinina (Carp, Crucian Carp, Gold-fish,
+Barbels, Gudgeons), <a href="#Page_589">589</a>—Rohteichthyina, <a href="#Page_596">596</a>—Leptobarbina,
+<a href="#Page_597">597</a>—Rasborina, <a href="#Page_597">597</a>—Semiplotina, <a href="#Page_598">598</a>—Xenocypridina,
+<a href="#Page_598">598</a>—Leuciscina (White fish, Tench, Dace, etc.), <a href="#Page_598">598</a>—Rhodeina,
+<a href="#Page_601">601</a>—Danionina, <a href="#Page_601">601</a>—Hypophthalmichthyina,
+<a href="#Page_602">602</a>—Abramidina (Bream, Bleak), <a href="#Page_602">602</a>—Homalopterina, <a href="#Page_604">604</a>—Cobitidina
+(Loaches), <a href="#Page_604">604</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families of Physostomi continued: Kneriidæ, <a href="#Page_606">606</a>—Characinidæ,
+<a href="#Page_606">606</a>—Cyprinodontidæ, <a href="#Page_613">613</a>—Heteropygii (Blind Fish of the
+Mammoth Cave), <a href="#Page_618">618</a>—Umbridæ, <a href="#Page_619">619</a>—Scombresocidæ (Gar-pike,
+Saury, Half-beak, Flying Fish), <a href="#Page_619">619</a>—Esocidæ (Pike),
+<a href="#Page_623">623</a>—Galaxiidæ, <a href="#Page_624">624</a>—Mormyridæ, <a href="#Page_625">625</a>—Sternoptychidæ,
+<a href="#Page_627">627</a>—Stomiatidæ, <a href="#Page_629">629</a>.</td>
+    <td><span class="pagenum" id="Page_xvi">[xvi]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families of Physostomi continued—<i>Salmonidæ</i>: Salmo, difficulty
+of distinguishing species, <a href="#Page_630">630</a>; constant specific characters,
+<a href="#Page_635">635</a>—hybrids, <a href="#Page_638">638</a>—sexual development, <a href="#Page_638">638</a>—migratory
+species and their retention in freshwater, <a href="#Page_639">639</a>—Growth of
+Salmonoids, <a href="#Page_641">641</a>—their domestication and acclimatisation,
+<a href="#Page_641">641</a>—species enumerated, <a href="#Page_642">642</a>—Smelt and Capelin, <a href="#Page_646">646</a>—Coregonus,
+<a href="#Page_647">647</a>—Grayling, <a href="#Page_649">649</a>—marine genera, <a href="#Page_650">650</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families of Physostomi continued: Percopsidæ, <a href="#Page_651">651</a>—Haplochitonidæ,
+<a href="#Page_651">651</a>—Gonorhynchidæ, <a href="#Page_652">652</a>—Hyodontidæ (Moon-eye),
+<a href="#Page_653">653</a>—Pantodontidæ, <a href="#Page_653">653</a>—Osteoglossidæ, <a href="#Page_653">653</a>—Clupeidæ
+(Herrings, Anchovies, Shads, Mossbanker, Menhaden, etc.),
+<a href="#Page_655">655</a>—Bathythrissidæ, <a href="#Page_663">663</a>—Chirocentridæ, <a href="#Page_663">663</a>—Alepocephalidæ,
+<a href="#Page_664">664</a>—Notopteridæ, <a href="#Page_664">664</a>—Halosauridæ, <a href="#Page_665">665</a>—Hoplopleuridæ,
+<a href="#Page_665">665</a>—Gymnotidæ (Electric Eel), <a href="#Page_666">666</a>—Symbranchidæ,
+<a href="#Page_668">668</a>—Murænidæ (Eels, Congers, Murænas, etc.), <a href="#Page_669">669</a>.</td>
+    <td></td>
+  </tr>
+  
+  <tr>
+    <td class="cht1 smcap" colspan="2">Fifth Order—Lophobranchii</td>
+    <td class="pag"><a href="#Page_678">678</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families: Solenostomidæ, <a href="#Page_678">678</a>—Syngnathidæ (Pipe-fishes, Sea-horses), <a href="#Page_679">679</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="cht1 smcap" colspan="2">Sixth Order—Plectognathi</td>
+    <td class="pag"><a href="#Page_683">683</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families: Sclerodermi (File-fishes, Coffer-fishes), <a href="#Page_684">684</a>—Gymnodontes
+(Globe-fishes, Sun-fish), <a href="#Page_686">686</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header1 smcap" colspan="3">Third Sub-class—Cyclostomata.</th>
+    </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Families: Petromyzontidæ (Lampreys), <a href="#Page_691">691</a>—Myxinidæ, <a href="#Page_694">694</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header1 smcap" colspan="3">Fourth Sub-class—Leptocardii.</th>
+    </tr>
+
+  <tr>
+    <td class="cht2" colspan="2">Family: Cirrhostomi (Lancelets), <a href="#Page_696">696</a>.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <th class="header1" colspan="3">APPENDIX.</th>
+    </tr>
+
+  <tr>
+    <td class="cht1" colspan="2">Directions for Collecting and Preserving Fishes</td>
+    <td><a href="#Page_697">697</a></td>
+  </tr>
+
+  <tr>
+    <td class="cht1" colspan="2">Alphabetical Index</td>
+    <td><a href="#Page_707">707</a></td>
+  </tr>
+</table>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_1">[1]</span></p>
+
+<h2 class="smaller">INTRODUCTORY REMARKS.</h2>
+</div>
+
+
+<p>According to the views generally adopted at present, all those
+Vertebrate animals are referred to the Class of Fishes, which living in
+water, breathe air dissolved in water by means of gills or branchiæ;
+whose heart consists of a single ventricle and single atrium; whose
+limbs, if present, are modified into fins, supplemented by unpaired,
+median fins; and whose skin is either naked, or covered with scales or
+osseous plates or bucklers. With few exceptions fishes are oviparous.
+However, there are not a few members of this Class which show a
+modification of one or more of these characteristics, as we shall see
+hereafter, and which, nevertheless, cannot be separated from it. The
+distinction between the Class of Fishes and that of Batrachians is very
+slight indeed.</p>
+
+<p>The branch of Zoology which treats of the internal and external
+structure of fishes, their mode of life, and their distribution in
+space and time, is termed Ichthyology.<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">[1]</a></p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_2">[2]</span></p>
+
+<h2 class="smaller">CHAPTER I.<br>
+<span class="subhed">HISTORY AND LITERATURE.</span></h2></div>
+
+<div class="sidenote">Aristotle.</div>
+
+<p class="p-left">The commencement of the history of Ichthyology coincides with that
+of Zoology generally. <span class="smcap">Aristotle</span> (384–322 <span class="allsmcap">B.C.</span>)
+had a perfect knowledge of the general structure of fishes, which
+he clearly discriminates from the Aquatic animals with lungs and
+mammæ, <i>i.e.</i> Cetaceans, and from the various groups of Aquatic
+Invertebrates. He says that “the special characteristics of the true
+fishes consist in the branchiæ and fins, the majority having four
+fins, but those of an elongate form, as the eels, having two only.
+Some, as the <i>Muræna</i>, lack the fins altogether. The Rays swim
+with their whole body, which is spread out. The branchiæ are sometimes
+furnished with an opercle, sometimes without one, as is the case in
+the cartilaginous fishes.... No fish has hairs or feathers; most are
+covered with scales, but some have a rough or smooth skin. The tongue
+is hard, often toothed; and sometimes so much adherent that it seems
+to be wanting. The eyes have no lids; nor are any ears or nostrils
+visible, for what takes the place of nostrils is a blind cavity.
+Nevertheless they have the senses of tasting, smelling, and hearing.
+All have blood. All scaly fishes are oviparous, but the cartilaginous
+fishes (with the exception of the Sea-devil, which Aristotle places
+along with them) are viviparous. All have a heart, liver, and
+gall-bladder; but kidneys and urinary bladder are absent. They vary
+much in the structure of their intestines: for whilst the mullet has
+a fleshy stomach like a bird, others have no<span class="pagenum" id="Page_3">[3]</span> stomachic dilatation.
+Pyloric coeca are close to the stomach, variable in number; there are
+even some, like the majority of the cartilaginous fishes, which have
+none whatever. Two bodies are situated along the spine, which have the
+function of testicles, and open towards the vent, and which are much
+enlarged in the spawning season. The scales become harder with age. Not
+being provided with lungs, they have no voice, but several can emit
+grunting sounds. They sleep like other animals. In the majority the
+females exceed the males in size; and in the Rays and Sharks the male
+is distinguished by an appendage on each side of the vent.”</p>
+
+<p>Aristotle’s information on the habits of fishes, their migrations, mode
+and time of propagation, utility, is, as far as it has been tested,
+surprisingly correct. Unfortunately, only too often we lack the means
+of recognising the species of which he gives a description. His ideas
+of specific distinction were as vague as those of the fishermen whose
+nomenclature he adopted; it never occurred to him that such popular
+names are subject to change, or may be entirely lost with time, and
+the difficulty of deciphering his species is further increased by the
+circumstance that popular names are often applied by him to the same
+fish, or that different stages of growth are designated by distinct
+names. The number of fishes known to Aristotle seems to have been about
+115, all of which are inhabitants of the Ægean Sea.</p>
+
+<p>That one man should have discovered so many truths, and formed so
+sure a base for Zoology, is less surprising than the fact that for
+about eighteen centuries a science which seemed to offer particular
+attractions to men gifted with power of observation, was no farther
+advanced. Yet this is the case. Aristotle’s disciples, as well as his
+successors, remained satisfied to be his copiers or commentators,
+and to collect fabulous stories or vague notions. With very few
+exceptions (such as <i>Ausonius</i>, who wrote a small poem, in which
+he describes<span class="pagenum" id="Page_4">[4]</span> from his own observations the fishes of the Mosel)
+authors entirely abandoned original research. And it was not until
+about the middle of the sixteenth century that Ichthyology made a new
+step in advance by the appearance of <i>Belon</i>, <i>Rondelet</i>, and
+<i>Salviani</i>, who almost simultaneously published their grand works,
+by which the idea of species was established definitely and for all
+times.</p>
+
+<hr class="tb">
+
+<div class="sidenote">Belon.</div>
+
+<p><span class="smcap">P. Belon</span> travelled in the countries bordering on the eastern
+part of the Mediterranean, in the years 1547–50; he collected rich
+stores of positive knowledge, which he deposited in several works. The
+one most important for the progress of Ichthyology is that entitled “De
+aquatilibus libri duo” (Paris 1553; small 4to.) Belon knows about 110
+fishes, of which he gives rude, but generally recognisable, figures. In
+his descriptions he pays regard to the classical as well as vernacular
+nomenclature, and states the outward characteristics, sometimes even
+the number of fin-rays, frequently also the most conspicuous anatomical
+peculiarities.</p>
+
+<p>Although Belon but rarely gives definitions of the terms used by him,
+it is generally not very difficult to ascertain the limits which
+he intended to assign to each division of aquatic animals. He very
+properly divides them into such as are provided with blood, and into
+those without it: two divisions, called in modern language Vertebrate
+and Invertebrate aquatic animals. The former are classified by him
+according to sizes, the further subdivisions being based on the
+structure of the skeleton, mode of propagation, number of limbs, form
+of the body, and on the physical character of the localities inhabited
+by fishes. This classification is as follows:—</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="chn">I.</td>
+    <td class="cht">The larger fishes or Cetaceans.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht2"><i>A.</i> Viviparous Cetaceans with bony skeletons (= Cetacea).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht2"><i>B.</i> Viviparous Amphibians.</td>
+    <td><span class="pagenum" id="Page_5">[5]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">1. “With four limbs: Seals, Hippopotamus, Beaver, Otter, and
+other aquatic Mammalia.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">2. With two limbs: Mermaids, etc.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht2"><i>C.</i> Oviparous Amphibians (= Reptiles and Frogs).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht2"><i>D.</i> Viviparous Cartilaginous fishes.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">1. Of an oblong form (= Sharks).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">2. Of a flat form (= Rays and Lophius).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht2"><i>E.</i> Oviparous Cartilaginous fishes (= Sturgeons and
+Silurus).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht2"><i>F.</i> Oviparous Cetaceans, with spines instead of bones (=
+large marine fishes, like the Thunny, Sword-fish, Sciænoids,
+Bass, Gadoids, Trachypterus).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">II.</td>
+    <td class="cht">Spinous Oviparous fishes of a flat form (= Pleuronectidæ).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">III.</td>
+    <td class="cht">Fishes of a high form, like Zeus.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">IV.</td>
+    <td class="cht">Fishes of a snake like form (= Eels, Belone, Sphyræna).</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">V.</td>
+    <td class="cht">Small Oviparous, spinous, scaly, marine fishes.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">1. Pelagic kinds.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">2. Littoral kinds.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn"></td>
+    <td class="cht3">3. Kinds inhabiting rocky localities.</td>
+    <td></td>
+  </tr>
+
+  <tr>
+    <td class="chn">VI.</td>
+    <td class="cht">Fluviatile and Lacustrine fishes.</td>
+    <td></td>
+  </tr>
+
+</table>
+
+<hr class="tb">
+
+<div class="sidenote">Salviani.</div>
+
+<p class="p-left">The work of the Roman ichthyologist, <span class="smcap">H. Salviani</span> (1514–72),
+is characteristic of the high social position which the author held
+as the physician of three popes. Its title is “Aquatilium animalium
+historia” (Rom. 1554–57, fol.) It treats exclusively of the fishes of
+Italy. Ninety-two species are figured on seventy-six plates which, as
+regards artistic execution, are masterpieces of that period, although
+those specific characteristics which nowadays constitute the value
+of a zoological drawing, were entirely overlooked by the author or
+artist. No attempt is made at a natural classification, but the allied
+forms generally are placed in close proximity. The descriptions are
+quite equal to those given by Belon, entering much into the details of
+the economy and usefulness of the several species, and were evidently
+composed with the view of collecting in a readable form all that might<span class="pagenum" id="Page_6">[6]</span>
+prove of interest to the class of society in which the author moved.
+Salviani’s work is of a high standard, most remarkable for the age in
+which he lived. It could not fail to convey valuable instruction, and
+to render Ichthyology popular in the country to the fauna of which it
+was devoted, but it would not have advanced Ichthyology as science
+generally; and in this respect Salviani is not to be compared with
+Rondelet or Belon.</p>
+
+<hr class="tb">
+
+<div class="sidenote">Rondelet.</div>
+
+<p class="p-left"><span class="smcap">G. Rondelet</span> (1507–1557) had the great advantage over Belon in
+having received a medical education at Paris, and more especially in
+having gone through a complete course of instruction in anatomy as a
+pupil of Guentherus of Andernach. This is conspicuous throughout his
+works—“Libri de Piscibus marinis” (Lugd. 1554, fol.); and “Universæ
+aquatilium historiæ pars altera” (Lugd. 1555, fol.) Nevertheless
+they cannot be regarded as more than considerably enlarged editions
+of Belon’s work. For although he worked independently of the latter,
+and differs from him in numerous details, the system adopted by
+him is characterised by the same absence of the true principles of
+classification. Rondelet had a much more extensive knowledge of
+details. His work is almost entirely limited to European, and chiefly
+Mediterranean, forms, and comprises not less than 197 marine and 47
+freshwater fishes. His descriptions are more complete and his figures
+much more accurate than those of Belon; and the specific account is
+preceded by introductory chapters in which he treats in a general
+manner on the distinctions, the external and internal parts, and on
+the economy of fishes. Like Belon, he had no conception of the various
+categories of classification—for instance, confounding throughout his
+work the terms “genus” and “species;” but he had intuitively a notion
+of what his successors called a “species,” and his principal object was
+to collect and give as much information as possible of such species.</p>
+
+<p><span class="pagenum" id="Page_7">[7]</span></p>
+
+<p>For nearly a century the works of Belon and Rondelet remained the
+standard works of Ichthyology; but this science did not remain
+stationary during this period. The attention of naturalists was now
+directed to the products of foreign countries, especially the Spanish
+and Dutch possessions in the New World; and in Europe the establishment
+of anatomical schools and academies led to the careful investigation
+of the internal anatomy of the most remarkable European forms. Limited
+as these efforts were as to their scope, being directed either only to
+the fauna of some district, or to the dissection of a single species,
+they were sufficiently numerous to enlarge the views of naturalists,
+and to destroy that fatal dependency on preceding authorities which had
+continued to keep in bonds the minds of even such men as Rondelet and
+Belon.</p>
+
+<div class="sidenote">W. Piso. G. Margrav.</div>
+
+<p class="p-left">The most noteworthy of those who were active in tropical countries
+are <span class="smcap">W. Piso</span> and <span class="smcap">G. Margrav</span>. They accompanied as
+physicians the Dutch Governor, Prince Moritz of Nassau, to Brazil
+(1637–44). Margrav especially studied the fauna of the country,
+and although he died before his return to Europe, his observations
+were published by his colleague, and embodied in a work “Historia
+naturalis Braziliæ” (Lugd. 1648, fol.), in which the fourth book
+treats of the fishes. He describes about 100 species, all of which
+had been previously unknown, in a manner far superior to that of his
+predecessors. The accompanying figures are not good, but nearly always
+recognisable, and giving a fair idea of the form of the fish. Margrav
+himself, with the aid of an artist, had made a most valuable collection
+of coloured drawings of the objects observed and described by him, but
+many years were allowed to pass before it was scientifically utilised
+by Bloch and others.</p>
+
+<div class="sidenote">Anatomists, 1600–1700.</div>
+
+<p class="p-left">Of the men who left records of their anatomical researches, we
+may mention <span class="smcap">Borelli</span> (1608–79), who wrote a work “De motu
+animalium” (Rom. 1680, 4to), in which he explained the mechanism of
+swimming, and the function of the air-bladder;<span class="pagenum" id="Page_8">[8]</span> <span class="smcap">M. Malpighi</span>
+(1628–94), who examined the optic nerve of the sword-fish; the
+celebrated <span class="smcap">J. Swammerdam</span> (1637–80), who described the
+intestines of numerous fishes; and <span class="smcap">J. Duverney</span> (1648–1730),
+who entered into detailed researches of the organs of respiration.</p>
+
+<hr class="tb">
+
+<p>A new era in the history of Ichthyology commences with <i>Ray</i>,
+<i>Willughby</i>, and <i>Artedi</i>, who were the first to recognise
+the true principles by which the natural affinities of animals should
+be determined. Their labours stand in so intimate a connection with
+each other that they represent only one stride in the progress of this
+science.</p>
+
+<hr class="tb">
+
+<div class="sidenote">Ray and Willughby</div>
+
+<p class="p-left"><span class="smcap">J. Ray</span> (born 1628 in Essex, died 1705), was the friend and
+guide of <span class="smcap">F. Willughby</span> (1635–72). They had recognised that a
+thorough reform of the treatment of the vegetable and animal kingdoms
+had become necessary; that the only way of bringing order into the
+existing chaos was that of arranging the various forms with regard to
+their structure; that they must cease to be burdened with inapplicable
+passages and quotations of the ancient writers, and to perpetuate
+the erroneous or vague notions of their predecessors. They abandoned
+speculation, and adhered to facts only. One of the first results, and
+perhaps the most important, of their method was, that having recognised
+the “species” as such, they defined this term, and fixed it as the
+base, from which all sound zoological knowledge has to start.</p>
+
+<p>Although they had divided their work thus that Ray attended to the
+plants principally, and Willughby to the animals, the “Historia
+piscium” (Oxford, 1686, fol.), which bears Willughby’s name on the
+titlepage, and was edited by Ray, is clearly their joint production. A
+great part of the observations contained in it were collected during
+their common journeys in Great Britain and on the Continent, and it is
+no exaggeration to say that at that time these two Englishmen<span class="pagenum" id="Page_9">[9]</span> knew the
+fishes of the Continent, especially those of Germany, better than any
+other Continental zoologist.</p>
+
+<p>By the definition of fishes as animals with blood, breathing by gills,
+provided with a single ventricle of the heart, covered with scales or
+naked; the Cetaceans are excluded. Yet, at a later period Ray appears
+to have been afraid of so great an innovation as the separation of
+whales from fishes, and, therefore, he invented a definition of fish
+which comprises both. The fishes proper are then arranged in the
+first place according to the cartilaginous or osseous nature of the
+skeleton; further subdivisions being formed with regard to the general
+form of the body, the presence or absence of ventral fins, the soft or
+spinous structure of the dorsal rays, the number of dorsal fins, etc.
+Not less than 420 species are thus arranged and described, of which
+about 180 were known to the authors from autopsy: a comparatively
+small proportion, descriptions and figures still forming at that time
+in a great measure a substitute for collections and museums. With the
+increasing accumulation of forms the want of a fixed nomenclature is
+now more and more felt.</p>
+
+<hr class="tb">
+
+<div class="sidenote">P. Artedi.</div>
+
+<p class="p-left"><span class="smcap">Peter Artedi</span> would have been a great ichthyologist if Ray or
+Willughby had never preceded him. But he was fully conscious of the
+fact that both had prepared the way for him, and therefore he derived
+all possible advantages from their works. Born in 1705 in Sweden, he
+studied with Linnæus at Upsala; from an early period he devoted himself
+entirely to the study of fishes, and was engaged in the arrangement and
+description of the ichthyological collection of <i>Seba</i>, a wealthy
+Dutchman who had formed the then perhaps richest museum, when he was
+accidentally drowned in one of the canals of Amsterdam in the year
+1734, at an age of twenty-nine years. His manuscripts were fortunately
+rescued by an Englishman, Cliffort, and edited by his early friend
+Linnæus.</p>
+
+<p><span class="pagenum" id="Page_10">[10]</span></p>
+
+<p>The work is divided into the following parts:—</p>
+
+<p>1. In the “Bibliotheca Ichthyologica” Artedi gives a very complete list
+of all preceding authors who have written on fishes, with a critical
+analysis of their works.</p>
+
+<p>2. The “Philosophia Ichthyologica” is devoted to a description of
+the external and internal parts of fishes; Artedi fixes a precise
+terminology of all the various modifications of the organs,
+distinguishes between those characters which determine a genus and such
+as indicate a species or merely a variety; in fact he establishes the
+method and principles which subsequently have guided every systematic
+ichthyologist.</p>
+
+<p>3. The “Genera Piscium” contains well-defined diagnoses of forty-five
+genera, for which he fixes an unchangeable nomenclature.</p>
+
+<p>4. In the “Species Piscium” descriptions of seventy-two species,
+examined by himself, are given; descriptions which even now are models
+of exactitude and method.</p>
+
+<p>5. Finally, in the “Synonymia Piscium” references to all previous
+authors are arranged for every species, very much in the same manner
+which is adopted in the systematic works of the present day.</p>
+
+<div class="sidenote">Linnæus.</div>
+
+<p class="p-left">Artedi has been justly called the Father of Ichthyology. So perfect was
+his treatment of the subject, that even <span class="smcap">Linnæus</span> could no more
+improve it, only modify and add to it; and as far as Ichthyology is
+concerned, Linnæus has scarcely done anything beyond applying binominal
+terms to the species properly described and classified by Artedi.</p>
+
+<p>Artedi had divided the fishes proper into four orders, viz.
+<i>Malacopterygii</i>, <i>Acanthopterygii</i>, <i>Branchiostegi</i>,
+and <i>Chondropterygii</i>, of which the third only, according to
+our present knowledge, appears to be singularly heterogeneous, as it
+comprises <i>Balistes</i>, <i>Ostracion</i>, <i>Cyclopterus</i>, and
+<i>Lophius</i>. Linnæus, besides separating the Cetaceans entirely from
+the class of fishes (at least since the 10th edition of the “Systema
+Naturæ”)<span class="pagenum" id="Page_11">[11]</span> abandoned Artedi’s order of Branchiostegi, but substituted
+a scarcely more natural combination by joining it with Artedi’s
+Chondropterygians, under the name of “Amphibia nantes.”</p>
+
+<p>His classification of the genera appears in the 12th edition of the
+“Systema,” thus—</p>
+
+<p class="smcap center">Amphibia Nantes.</p>
+
+<p class="center"><i>Spiraculis compositis.</i></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Petromyzon.</li>
+  <li>Raia.</li>
+  <li>Squalus.</li>
+  <li>Chimæra.</li>
+</ul>
+</div>  
+
+<p class="center"><i>Spiraculis solitariis.</i></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Lophius.</li>
+  <li>Acipenser.</li>
+  <li>Cyclopterus.</li>
+  <li>Balistes.</li>
+  <li>Ostracion.</li>
+  <li>Tetrodon.</li>
+  <li>Diodon.</li>
+  <li>Centriscus.</li>
+  <li>Syngnathus.</li>
+  <li>Pegasus.</li>
+</ul>
+</div>  
+
+<p class="smcap center">Pisces Apodes.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Muræna.</li>
+  <li>Gymnotus.</li>
+  <li>Trichiurus.</li>
+  <li>Anarhichas.</li>
+  <li>Ammodytes.</li>
+  <li>Ophidium.</li>
+  <li>Stromateus.</li>
+  <li>Xiphias.</li>
+</ul>
+</div>  
+
+<p class="smcap center">Pisces Jugulares.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Callionymus.</li>
+  <li>Uranoscopus.</li>
+  <li>Trachinus.</li>
+  <li>Gadus.</li>
+  <li>Blennius.</li>
+</ul>
+</div>  
+
+<p class="smcap center">Pisces Thoracici.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Cepola.</li>
+  <li>Echeneis.</li>
+  <li>Coryphæna.</li>
+  <li>Gobius.</li>
+  <li>Cottus.</li>
+  <li>Scorpæna.</li>
+  <li>Zeus.</li>
+  <li>Pleuronectes.</li>
+  <li>Chæetodon.</li>
+  <li>Sparus.</li>
+  <li>Labrus.</li>
+  <li>Sciæna.</li>
+  <li>Perca.</li>
+  <li>Gasterosteus.</li>
+  <li>Scomber.</li>
+  <li>Mullus.</li>
+  <li>Trigla.</li>
+</ul>
+</div>  
+
+<p class="smcap center">Pisces Abdominales.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Cobitis.</li>
+  <li>Amia.</li>
+  <li>Silurus.</li>
+  <li>Teuthis.</li>
+  <li>Loricaria.</li>
+  <li>Salmo.</li>
+  <li>Fistularia.</li>
+  <li>Esox.</li>
+  <li>Elops.</li>
+  <li>Argentina.</li>
+  <li>Atherina.</li>
+  <li>Mugil.</li>
+  <li>Mormyrus.</li>
+  <li>Exocœtus.</li>
+  <li>Polynemus.</li>
+  <li>Clupea.</li>
+  <li>Cyprinus.</li>
+</ul>
+</div>  
+
+<p><span class="pagenum" id="Page_12">[12]</span></p>
+
+<div class="sidenote">Gronow and Klein.</div>
+
+<p class="p-left">Two contemporaries of <i>Linnæus</i> attempted a systematic arrangement
+of fishes; both had considerable opportunities for their study,
+especially in possessing extensive collections; but neither exercised
+any influence on the progress of Ichthyology. The one, <span class="smcap">L. T.
+Gronow</span>, a German who resided in Holland, closely followed the
+arrangements proposed by Artedi and Linnæus, and increased the
+number of genera and species from the contents of his own museum. He
+published two works, “Museum Ichthyologicum” (Lugd. 1754–6, fol.), and
+“Zoophylacium” (Lugd. 1763–81, fol.); a posthumous work, containing
+numerous excellent descriptions of new forms was published by J. E.
+Gray in 1854 under the title of “Systema Ichthyologicum.” To Gronow
+also is due the invention of preparing flat skins of fishes in a dry
+state, and preserving them in the manner of a herbarium. The specimens
+thus prepared by him belong to the oldest which have been preserved
+down to our time.</p>
+
+<p>Much less important are the ichthyological labours of <span class="smcap">J. T.
+Klein</span> (1685–1759). They are embodied in five parts (<i>Missus</i>)
+of a work entitled “Historia naturalis piscium” (Sedæ, 1740–9, 4to.)
+He regarded a system merely as the means of recognising the various
+forms of animals, not as the expression of their natural affinities;
+and that method seemed to him to be the most perfect by which an animal
+could be most readily determined. He eschewed all reference to minute
+or anatomical characters. Hence his system is a series of the most
+unnatural combinations, and we cannot be surprised that Linnæus passed
+in silence over Klein’s labours.</p>
+
+<hr class="tb">
+
+<div class="sidenote">Pupils and Successors of Linnæus</div>
+
+<p class="p-left">The works of Artedi and Linnæus excited fresh activity, more especially
+in Scandinavia, Holland, Germany, and England, such as has not been
+equalled in the history of biological science either before or
+after. Whilst some of the pupils and followers of Linnæus devoted
+themselves to an<span class="pagenum" id="Page_13">[13]</span> examination and study of the fauna of their native
+countries, others proceeded on voyages of discovery to foreign and
+distant countries. Of these latter the following may be specially
+mentioned:—<i>O. Fabricius</i> worked out the Fauna of Greenland,
+<i>Kalm</i> collected in North America, <i>Hasselquist</i> in Egypt
+and Palestine, <i>Brünnich</i> in the Mediterranean, <i>Osbeck</i> in
+Java and China, <i>Thurnberg</i> in Japan; <i>Forskål</i> examined and
+described the fishes of the Red Sea; <i>Steller</i>, <i>Pallas</i>,
+<i>S. T. Gmelin</i>, and <i>Güldenstedt</i> traversed nearly the whole
+of the Russian Empire in Europe and Asia. Others attached themselves
+as naturalists to the celebrated circumnavigators of the last century,
+like the two <i>Forsters</i> (father and son), and <i>Solander</i>, who
+accompanied Cook; <i>Commerson</i>, who travelled with Bougainville;
+and <i>Sonnerat</i>. Numerous new and startling forms were discovered
+by those men, and the foundation was laid of the knowledge of the
+geographical distribution of animals.</p>
+
+<p>Of those who studied the fishes of their native country the most
+celebrated are <i>Pennant</i> (Great Britain), <i>O. F. Müller</i>
+(Denmark), <i>Duhamel</i> (France), <i>Meidinger</i> (Austria),
+<i>Cornide</i> (Spain), <i>Parra</i> (Cuba).</p>
+
+<p>The materials brought together by those and other zoologists were so
+numerous that, not long after the death of Linnæus, the necessity was
+felt of collecting them in a compendious form. Several compilators
+undertook this task; they embodied the recent discoveries in new
+editions of Artedi’s and Linné’s classical works, but not possessing
+either a knowledge of the subject or any critical discernment, they
+only succeeded in covering those noble monuments under a mass of
+confused rubbish. For Ichthyology it was fortunate that two men at
+least, Bloch and Lacépède, made it a subject of long and original
+research.</p>
+
+<hr class="tb">
+
+<div class="sidenote">M. E. Bloch.</div>
+
+<p class="p-left"><span class="smcap">Mark Eliezer Bloch</span>, born in the year 1723 at Anspach in
+Germany, practised as a physician in Berlin; he had reached<span class="pagenum" id="Page_14">[14]</span> an age
+of fifty-six years when he commenced to write on ichthyological
+subjects. To commence at his age a work in which he intended not only
+to give full descriptions of the species known to him from specimens
+or drawings, but also to illustrate every species in a style truly
+magnificent for his time, was an undertaking of the execution of which
+an ordinary man would have despaired. Yet he accomplished not only this
+task, but even more, as we shall see hereafter.</p>
+
+<p>His work consists of two divisions:—</p>
+
+<p>1. “Oeconomische Naturgeschichte der Fische Deutschlands” (Berl.
+1782–4, 4to. Plates in fol.)</p>
+
+<p>2. “Naturgeschichte der auslændischen Fische” (Berl. 1785–95, 4to.
+Plates in fol.)</p>
+
+<p>Bloch’s work is unique, and probably will for ever remain so. Although
+Cuvier fifty years later undertook a similar general work on fishes,
+the subject had then become too extensive to allow of an attempt of
+giving illustrations of all the species, or illustrations of a similar
+size and costliness.</p>
+
+<p>The first division of the work, which is devoted to a description of
+the fishes of Germany, is entirely original, and based upon Bloch’s
+own observations. His descriptions as well as figures were made from
+nature, and are, with but few exceptions, still serviceable; many
+continue to be the best existing in literature.</p>
+
+<p>Bloch was less fortunate and is much less reliable in his natural
+history of foreign fishes. For many of the species he had to rely
+on more or less incorrect drawings and descriptions of travellers;
+frequently, also, he was deceived as to the origin of specimens which
+he acquired by purchase. Hence his accounts contain numerous confusing
+errors which it would have been difficult to correct, if not nearly the
+whole of the materials on which his work is based had been preserved in
+the collections at Berlin.</p>
+
+<p>After the completion of his Ichthyology Bloch occupied<span class="pagenum" id="Page_15">[15]</span> himself with
+systematic work. He prepared a general system of fishes, in which he
+arranged not only those described in his great work, but also those
+with which he had become acquainted afterwards from the descriptions of
+others. The work was ably edited and published after Bloch’s death by
+a philologist, <i>J. G. Schneider</i>, under the title “M. E. Blochii
+Systema ichthyologiæ iconibus ex. illustratum” (Berl. 1801, 8vo.) The
+number of species enumerated in it amounts to 1519. The system is
+based upon the number of the fins, the various orders being termed
+<i>Hendecapterygii</i>, <i>Decapterygii</i>, etc. We need not add that
+an artificial method like this led to the most unnatural combinations
+or severances.</p>
+
+<div class="sidenote">Lacépède.</div>
+
+<p class="p-left">Bloch’s Ichthyology remained for many years the standard work, and,
+by the great number of excellent illustrations, proved a most useful
+guide to the student. But as regards originality of thought, Bloch was
+far surpassed by his contemporary, <span class="smcap">B. G. E. de Lacépède</span>, born
+at Agen, in France, in 1756, a man of great and general erudition, who
+died as Professor of the Museum of Natural History of Paris in 1826.</p>
+
+<p>Lacépède had to contend with great difficulties in the preparation
+of his “Histoire des Poissons” (Paris, 1798–1803, 4to, in 5 vols.),
+which was written during the most disturbed period of the French
+Revolution. A great part of it was composed whilst the author was
+separated from collections and books, and had to rely on his notes and
+manuscripts only. Even the works of Bloch and other contemporaneous
+authors remained unknown, or at least inaccessible, to him for a long
+time. Therefore we cannot be surprised that his work abounds in all
+those errors to which a compiler is subject. The same species not only
+appears under two and more distinct specific names, but it sometimes
+happens that the author understands so little the source from which
+he derives his information that the description is referred to one
+genus and the accompanying figure to another. The names of genera are
+unduly<span class="pagenum" id="Page_16">[16]</span> multiplied; and the figures with which the work is illustrated
+are far inferior to those of Bloch. Thus the influence of Lacépède
+on the progress of Ichthyology was infinitely less than that of his
+fellow-labourer; and the labour caused to his successors by correcting
+the numerous errors into which he has fallen, probably outweighs the
+assistance which they derived from his work.</p>
+
+<div class="sidenote">Anatomists.</div>
+
+<p class="p-left">The work of the principal cultivators of Ichthyology in the period
+between Ray and Lacépède was chiefly systematic and descriptive, but
+also the internal organisation of fishes received attention from
+more than one great anatomist. <i>Haller</i>, <i>Camper</i>, and
+<i>Hunter</i>, examined the nervous system and organs of sense; and
+more especially <i>Alexander Monro</i> (the son) published a classical
+work, “The Structure and Physiology of Fishes explained and compared
+with those of Man and other Animals” (Edinb. 1785, fol.) The electric
+organs of fishes (<i>Torpedo</i> and <i>Gymnotus</i>) were examined
+by <i>Réaumur</i>, <i>Allamand</i>, <i>Bancroft</i>, <i>Walsh</i>,
+and still more exactly by <i>J. Hunter</i>. The mystery of the
+propagation of the Eel called forth a large number of essays, and even
+the artificial propagation of Salmonidæ was known and practised by
+<i>Gleditsch</i> (1764).</p>
+
+<div class="sidenote">Faunists.</div>
+
+<p class="p-left">Bloch and Lacépède’s works were almost immediately succeeded by the
+labours of <i>Cuvier</i>, but his early publications were of necessity
+tentative, preliminary, and fragmentary, so that a short period elapsed
+before the spirit infused by this great anatomist into Ichthyology
+could exercise its influence on all workers in this field. Several
+of such antecuvierian works must be mentioned on account of their
+importance to our knowledge of certain Faunas: the “Descriptions
+and Figures of Two Hundred Fishes collected at Vizagapatam on the
+coast of Coromandel” (Lond. 1803; 2 vols. in fol.), by <i>Patrick
+Russel</i>; and “An Account of the Fishes found in the River Ganges and
+its branches” (Edinb. 1822; 2 vols. in<span class="pagenum" id="Page_17">[17]</span> 4to), by <i>F. Hamilton</i>
+(formerly <i>Buchanan</i>)—works distinguished by a greater accuracy
+of their drawings (especially in the latter), than was ever attained
+before. A “Natural History of British Fishes” was published by <i>E.
+Donovan</i> (Lond. 8vo, 1802–8); and the Mediterranean Fauna formed
+the study of the lifetime of <i>A. Risso</i> (“Ichthyologie de Nice.”
+Paris, 1810, 8vo; and “Histoire naturelle de l’Europe Meridionale.”
+Paris, 1827, 8vo). A slight beginning in the description of the fishes
+of the United States was made by <i>S. L. Mitchell</i>, who published,
+besides various papers, a “Memoir on the Ichthyology of New York,” in
+1815.<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">[2]</a></p>
+
+<hr class="tb">
+
+<div class="sidenote">G. Cuvier.</div>
+
+<p class="p-left"><span class="smcap">G. Cuvier</span> did not occupy himself with the study of fishes
+merely because this class formed part of the “Règne animal,” but he
+devoted himself to it with particular predilection. The investigation
+of their anatomy, and especially of their skeleton, was taken up
+by him at an early period, and continued until he had succeeded in
+completing so perfect a framework of the system of the whole class
+that his immediate successors could content themselves with filling up
+those details for which their master had no leisure. Indefatigable in
+examining all the external and internal characters of the fishes of a
+rich collection, he ascertained the natural affinities of the infinite
+variety of fishes, and accurately defined the divisions, orders,
+families, and genera of the class, as they appear in the various
+editions of the “Règne animal.” His industry equalled his genius: he
+opened connections with almost every accessible part of the globe; not
+only French travellers and naturalists, but also Germans, Englishmen,
+Americans, rivalled one another to assist him with collections; and
+for many years the Muséum of the Jardin des Plantes was the centre
+where all ichthyological treasures were deposited. Thus Cuvier<span class="pagenum" id="Page_18">[18]</span> brought
+together a collection the like of which had never been seen before,
+and which, as it contains all the materials on which his labours
+were based, must still be considered to be the most important. Soon
+after the year 1820, Cuvier, assisted by one of his pupils, <span class="smcap">A.
+Valenciennes</span>, commenced his great work on fishes, “Histoire
+naturelles des Poissons,” of which the first volume appeared in 1828.
+The earlier volumes, in which Cuvier himself took his share, bear
+evidence of the freshness and love with which both authors devoted
+themselves to their task. After Cuvier’s death in 1832 the work was
+left entirely in the hands of Valenciennes, whose energy and interest
+gradually slackened, to rise to the old standard in some parts only,
+as, for instance, in the treatise on the Herring. He left the work
+unfinished with the twenty-second volume (1848), which treats of the
+Salmonoids. Yet, incomplete as it is, it is indispensable to the
+student.</p>
+
+<p>There exist several editions of the work, which, however, have the same
+text. One, printed in 8vo, with coloured or plain figures, is the one
+in common use among ichthyologists. A more luxurious edition in 4to has
+a different pagination, and therefore is most inconvenient to use.</p>
+
+<p>As mentioned above, the various parts of the work are very unequally
+worked out. Many of the species are described in so masterly a
+manner that a greater excellency of method can hardly be conceived.
+The history of the literature of these species is entered into with
+minuteness and critical discernment; but in the later volumes, numerous
+species are introduced into the system without any description, or
+with a few words only, comparing a species with one or more of its
+congeners. Cuvier himself, at a late period of his life, seems to have
+grown indifferent as to the exact definition of his species: a failing
+commonly observed among Zoologists when attention to descriptive
+details becomes to them a tedious task. What is more surprising is,
+that a man<span class="pagenum" id="Page_19">[19]</span> of his anatomical and physiological knowledge should have
+overlooked the fact that secondary sexual characters are developed in
+fishes as in any other class of animals, and that fishes undergo great
+changes during growth; and, consequently, that he described almost
+all such sexual forms and different stages of growth under distinct
+specific and even generic names.</p>
+
+<p>The system finally adopted by Cuvier is the following:—</p>
+
+<p class="center"><i>A.</i> <span class="smcap">Poissons Osseux.</span></p>
+
+
+<p class="center">I.—<span class="allsmcap">A BRANCHIES EN PEIGNES OU EN LAMES.</span></p>
+
+
+<p class="center">1. <span class="allsmcap">A MÂCHOIRE SUPÉRIEURE LIBRE.</span></p>
+
+
+<p class="center">a. <i>Acanthoptérygiens.</i></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Percoïdes.</li>
+  <li>Polynèmes.</li>
+  <li>Mulles.</li>
+  <li>Joues cuirassées.</li>
+  <li>Scienoïdes.</li>
+  <li>Sparoïdes.</li>
+  <li>Chétodonoïdes.</li>
+  <li>Scomberoïdes.</li>
+  <li>Muges.</li>
+  <li>Branchies labyrinthiques.</li>
+  <li>Lophioïdes.</li>
+  <li>Gobioïdes.</li>
+  <li>Labroïdes.</li>
+</ul>
+</div>  
+
+<p class="center">b. <i>Malacoptérygiens.</i></p>
+
+<p class="center"><i>Abdominaux.</i></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Cyprinoïdes.</li>
+  <li>Siluroïdes.</li>
+  <li>Salmonoïdes.</li>
+  <li>Clupeoïdes.</li>
+  <li>Lucioïdes.</li>
+</ul>
+</div>  
+
+<p class="center"><i>Subbrachiens.</i></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Sparoïdes.</li>
+  <li>Pleuronectes.</li>
+  <li>Discoboles.</li>
+</ul>
+</div>  
+
+<p class="center"><i>Apodes.</i></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Murenoïdes.</li>
+</ul>
+</div>  
+
+<p class="center">2. <span class="allsmcap">A MÂCHOIRE SUPÉRIEURE FIXÉE.</span></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Sclérodermes.</li>
+  <li>Gymnodontes.</li>
+</ul>
+</div>  
+
+<p class="center">II. <span class="allsmcap">A BRANCHIES EN FORME DE HOUPPES.</span></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Lophobranches.</li>
+</ul>
+</div>  
+
+<p class="center"><i>B.</i> <span class="smcap">Cartilagineux ou Chondroptérygiens.</span></p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Sturioniens.</li>
+  <li>Plagiostomes.</li>
+  <li>Cyclostomes.</li>
+</ul>
+</div>  
+
+<p>We have to compare this system with that of Linnæus if we wish
+to measure the gigantic stride Ichthyology has made during the
+intervening period of seventy years. The various characters employed
+for classification have been examined<span class="pagenum" id="Page_20">[20]</span> throughout the whole class,
+and their relative importance has been duly weighed and understood.
+Though Linnæus had formed a category of “Amphibia nantes” for fishes
+with a cartilaginous skeleton, which should coincide with Cuvier’s
+“Poissons Cartilagineux,” he had failed to understand the very nature
+of cartilage, apparently comprising by this term any skeletal framework
+of less firmity than ordinary bone. Hence he considered <i>Lophius</i>,
+<i>Cyclopterus</i>, <i>Syngnathus</i> to be cartilaginous fishes.
+Adopting the position and development of the ventral fins as a
+highly important character, he was obliged to associate fishes with
+rudimentary and inconspicuous ventral fins, like <i>Trichiurus</i>,
+<i>Xiphias</i>, etc., with the true Eels. The important category of
+a “family” appears now in Cuvier’s system fully established as that
+intermediate between genus and order. Important changes in Cuvier’s
+system have been made and proposed by his successors, but in the main
+it is still that of the present day.</p>
+
+<p>Cuvier had extended his researches beyond the living forms, into
+the field of palæontology; he was the first to observe the close
+resemblance of the scales of the fossil <i>Palæoniscus</i> to
+those of the living <i>Polypterus</i> and <i>Lepidosteus</i>, the
+prolongation and identity of structure of the upper caudal lobe in
+<i>Palæoniscus</i> and the Sturgeons, the presence of peculiar “fulcra”
+on the anterior margin of the dorsal fin in <i>Palæoniscus</i> and
+<i>Lepidosteus</i>: inferring from these facts that that fossil
+genus was allied <i>either</i> to the Sturgeons <i>or</i> to
+<i>Lepidosteus</i>. But it did not occur to him that there was a close
+relationship between those recent fishes. <i>Lepidosteus</i> and, with
+it, the fossil genus remained in his system a member of the order of
+<i>Malacopterygii abdominales</i>.</p>
+
+<p>It was left to <span class="smcap">L. Agassiz</span> (born 1807, died 1873) to point out
+the importance of the character of the structure of the scales, and to
+open a path towards the knowledge of a whole new sub-class of fishes,
+the <i>Ganoidei</i>.</p>
+
+<p><span class="pagenum" id="Page_21">[21]</span></p>
+
+<p>Impressed with the fact that the peculiar scales of <i>Polypterus</i>
+and <i>Lepidosteus</i> are common to all fossil osseous fishes down to
+the chalk, he takes the structure of the scales generally as the base
+for an ichthyological system, and distinguishes four orders:—</p>
+
+<p>1. <i>Placoids.</i>—Without scales proper, but with scales of enamel,
+sometimes large, sometimes small and reduced to mere points (Rays,
+Sharks, and Cyclostomi, with the fossil <i>Hybodontes</i>).</p>
+
+<p>2. <i>Ganoids.</i>—With angular bony scales, covered with a thick
+stratum of enamel: to this order belong the fossil Lepidoides,
+Sauroides, Pycnodontes, and Coelacanthi; the recent Polypterus,
+Lepidosteus, Sclerodermi, Gymnodontes, Lophobranches, and Siluroides;
+also the Sturgeons.</p>
+
+<p>3. <i>Ctenoids.</i>—With rough scales, which have their free margins
+denticulated: Chætodontidæ, Pleuronectidæ, Percidæ, Polyacanthi,
+Sciænidæ, Sparidæ, Scorpænidæ, Aulostomi.</p>
+
+<p>4. <i>Cycloids.</i>—With smooth scales, the hind margin of which
+lacks denticulation: Labridæ, Mugilidæ, Scombridæ, Gadoidei, Gobiidæ,
+Murænidæ, Lucioidei, Salmonidæ, Clupeidæ, Cyprinidæ.</p>
+
+<p>We have no hesitation in affirming that if Agassiz had had an
+opportunity of acquiring a more extensive and intimate knowledge of
+existing fishes before his energies were absorbed in the study of
+their fossil remains, he himself would have recognised the artificial
+character of his classification. The distinctions between cycloid and
+ctenoid scales, between placoid and ganoid fishes are vague, and can
+hardly be maintained. As far as the living and post-cretacean forms
+are concerned, the vantage-ground gained by Cuvier was abandoned
+by him; and therefore his system could never supersede that of his
+predecessors, and finally shared the fate of every classification based
+on the modifications of one organ only. But Agassiz has the merit of
+having opened an immense new<span class="pagenum" id="Page_22">[22]</span> field of research by his study of the
+infinite variety of fossil forms. In his principal work, “Recherches
+sur les Poissons fossiles,” (Neuchatel, 1833–43, 4to, atlas in fol.),
+he placed them before the world arranged in a methodical manner, with
+excellent descriptions and illustrations. His power of discernment and
+penetration in determining even the most fragmentary remains is truly
+astonishing; and if his order of Ganoids is an assemblage of forms very
+different from that as it is circumscribed now, he was at any rate the
+first who recognised that such an order of fishes exists.</p>
+
+<hr class="tb">
+
+<div class="sidenote">J. Müller.</div>
+
+<p class="p-left">The discoverer of the <i>Ganoidei</i> was succeeded by their explorer,
+<span class="smcap">Johannes Müller</span> (born 1801, died 1858). In his classical
+memoir “Ueber den Bau und die Grenzen der Ganoiden” (Berlin, 1846;
+4to), he showed that the Ganoids differed from all the other osseous
+fishes, and agreed with the Plagiostomes, in the structure of their
+heart. By this primary character, all heterogeneous elements, as
+<i>Siluroids</i>, <i>Osteoglossidæ</i>, etc., were eliminated from the
+order as understood by Agassiz. On the other hand, he did not recognise
+the affinity of <i>Lepidosiren</i> to the Ganoids, but established for
+it a distinct sub-class, <i>Dipnoi</i>, which he placed at the opposite
+end of the system. By his researches into the anatomy of the Lampreys
+and Amphioxus, their typical distinctness from other cartilaginous
+fishes was proved; they became the types of two other sub-classes,
+<i>Cyclostomi</i> and <i>Leptocardii</i>.</p>
+
+<p>Müller proposed several other not unimportant modifications of the
+Cuvierian system; and although all cannot be maintained as the most
+natural arrangements, yet his researches have given us a much more
+complete knowledge of the organisation of the Teleosteous fishes,
+and later enquiries have shown that, on the whole, the combinations
+proposed by him require only some further modification and another
+definition to render them perfectly natural.</p>
+
+<p><span class="pagenum" id="Page_23">[23]</span></p>
+
+<p>Under the name of <i>Pharyngognathi</i> he combined fishes with
+the lower pharyngeals coalesced into one bone, viz. the Labroids,
+Chromides, and Scombresoces. The association of the third family with
+the two former seemed to himself a somewhat arbitrary proceeding; and
+it had to be abandoned again, when a number of fishes which cannot be
+separated from the Acanthopterygians, were found to possess the same
+united pharyngeals.</p>
+
+<p>A more natural combination is the union of the Cod-fishes with the
+Flat-fishes into the order <i>Anacanthini</i>. Flat-fishes are in fact
+nothing but asymmetrical Cod-fishes. Müller separates them from the
+remaining Malacopterygians by the absence of a connecting duct between
+the air-bladder and oesophagus. However, it must be admitted that the
+examination of those fishes, and especially of the young stages, is not
+complete enough to raise the question beyond every doubt, whether the
+presence or absence of that duct is an absolutely distinctive character
+between Anacanths and Malacopterygians.</p>
+
+<p>Many of the families established by Cuvier were reexamined and better
+defined by Müller, as may be seen from the following outline of his
+system:—</p>
+
+<p class="center">Sub-classis I.—Dipnoi.</p>
+
+
+<p class="center">Ordo I.—Sirenoidei.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Sirenoidei.</li>
+</ul>
+</div>  
+
+<p class="center">Sub-classis II.—Teleostei.</p>
+
+
+<p class="center">Ordo I.—Acanthopteri.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Percoidei.</li>
+  <li>&emsp;„&emsp;2. Cataphracti.</li>
+  <li>&emsp;„&emsp;3. Sparoidei.</li>
+  <li>&emsp;„&emsp;4. Sciænoidei.</li>
+  <li>&emsp;„&emsp;5. Labyrinthiformes.</li>
+  <li>&emsp;„&emsp;6. Mugiloidei.</li>
+  <li>&emsp;„&emsp;7. Notacanthini.</li>
+  <li>&emsp;„&emsp;8. Scomberoidei.</li>
+  <li>&emsp;„&emsp;9. Squamipennes.</li>
+  <li>&emsp;„&ensp;10. Taenioidei.</li>
+  <li>&emsp;„&ensp;11. Gobioidei.</li>
+  <li>&emsp;„&ensp;12. Blennioidei.</li>
+  <li>&emsp;„&ensp;13. Pediculati.</li>
+  <li>&emsp;„&ensp;14. Theutyes.</li>
+  <li>&emsp;„&ensp;15. Fistulares.</li>
+</ul>
+</div>  
+
+<p><span class="pagenum" id="Page_24">[24]</span></p>
+
+
+<p class="center">Ordo II.—Anacanthini.</p>
+
+
+<p class="center">Sub-ordo I.—Anacanthini sub-brachii.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Gadoidei.</li>
+  <li>&emsp;„&emsp;2. Pleuronectides.</li>
+</ul>
+</div>  
+
+<p class="center">Sub-ordo II.—Anacanthini apodes.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Ophidini.</li>
+</ul>
+</div>  
+
+<p class="center">Ordo III.—Pharyngognathi.</p>
+
+
+<p class="center">Sub-ordo I.—Pharyngognathi acanthopterygii.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Labroidei cycloidei.</li>
+  <li>&emsp;„&emsp;2. Labroidei ctenoidei.</li>
+  <li>&emsp;„&emsp;3. Chromides.</li>
+</ul>
+</div>  
+
+<p class="center">Sub-ordo II.—Pharyngognathi malacopterygii.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Scomberesoces.</li>
+</ul>
+</div>  
+
+<p class="center">Ordo IV.—Physostomi.</p>
+
+
+<p class="center">Sub-ordo I.—Physostomi abdominales.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Siluroidei.</li>
+  <li>&emsp;„&emsp;2. Cyprinoidei.</li>
+  <li>&emsp;„&emsp;3. Characini.</li>
+  <li>&emsp;„&emsp;4. Cyprinodontes.</li>
+  <li>&emsp;„&emsp;5. Mormyri.</li>
+  <li>&emsp;„&emsp;6. Esoces.</li>
+  <li>&emsp;„&emsp;7. Galaxiæ.</li>
+  <li>&emsp;„&emsp;8. Salmones.</li>
+  <li>&emsp;„&emsp;9. Scopelini.</li>
+  <li>&emsp;„&ensp;10. Clupeidæ.</li>
+  <li>&emsp;„&ensp;11. Heteropygii.</li>
+</ul>
+</div>  
+
+<p class="center">Sub-ordo II.—Physostomi apodes s. anguillares.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 12. Murænoidei.</li>
+  <li>&emsp;„&ensp;13. Gymnotini.</li>
+  <li>&emsp;„&ensp;14. Symbranchii.</li>
+</ul>
+</div>  
+
+<p class="center">Ordo V.—Plectognathi.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Balistini.</li>
+  <li>&emsp;„&emsp;2. Ostraciones.</li>
+  <li>&emsp;„&emsp;3. Gymnodontes.</li>
+</ul>
+</div>  
+
+<p class="center">Ordo VI.—Lophobranchii.</p>
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Lophobranchi.</li>
+</ul>
+</div>  
+
+<p><span class="pagenum" id="Page_25">[25]</span></p>
+
+
+<p class="center">Sub-classis III.—Ganoidei.</p>
+
+
+<p class="center">Ordo I.—Holostei.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Lepidosteini.</li>
+  <li>&emsp;„&emsp;2. Polypterini.</li>
+</ul>
+</div>  
+
+<p class="center">Ordo II.—Chondrostei.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Acipenserini,</li>
+  <li>&emsp;„&emsp;2. Spatulariæ.</li>
+</ul>
+</div>  
+
+<p class="center">Sub-classis IV.—Elasmobranchi s. Selachii.</p>
+
+
+<p class="center">Ordo I.—Plagiostomi.</p>
+
+
+<p class="center">Sub-ordo I.—Squalidæ.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Scyllia.</li>
+  <li>&emsp;„&emsp;2. Nyctitantes.</li>
+  <li>&emsp;„&emsp;3. Lamnoidei.</li>
+  <li>&emsp;„&emsp;4. Alopeciæ.</li>
+  <li>&emsp;„&emsp;5. Cestraciones.</li>
+  <li>&emsp;„&emsp;6. Rhinodontes.</li>
+  <li>&emsp;„&emsp;7. Notidani.</li>
+  <li>&emsp;„&emsp;8. Spinaces.</li>
+  <li>&emsp;„&emsp;9. Scymnoidei.</li>
+  <li>&emsp;„&ensp;10. Squatinæ.</li>
+
+</ul>
+</div>  
+
+<p class="center">Sub-ordo II.—Rajidæ.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 11. Squatinorajæ.</li>
+  <li>&emsp;„&ensp;12. Torpedines.</li>
+  <li>&emsp;„&ensp;13. Rajæ.</li>
+  <li>&emsp;„&ensp;14. Trygones.</li>
+  <li>&emsp;„&ensp;15. Myliobatides.</li>
+  <li>&emsp;„&ensp;16. Cephalopteræ.</li>
+</ul>
+</div>  
+
+<p class="center">Ordo II.—Holocephali.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Chimaeræ.</li>
+</ul>
+</div>  
+
+<p class="center">Sub-classis V.—Marsipobranchii s. Cyclostomi.</p>
+
+
+<p class="center">Ordo I.—Hyperoartii.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Petromyzonini.</li>
+</ul>
+</div>  
+
+<p class="center">Ordo II.—Hyperotreti.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Myxinoidei.</li>
+</ul>
+</div>  
+
+<p class="center">Sub-classis VI.—Leptocardii.</p>
+
+
+<p class="center">Ordo I.—Amphioxini.</p>
+
+<div class="parent">
+<ul class="left smaller" style="margin-top: 0em">
+  <li>Fam. 1. Amphioxini.</li>
+</ul>
+</div>  
+
+<div class="sidenote">Discovery of Ceratodus.</div>
+
+<p class="p-left">The discovery (in the year 1871) of a living representative of a
+genus hitherto believed to be long extinct, <i>Ceratodus</i>,<span class="pagenum" id="Page_26">[26]</span> threw
+a new light on the affinities of Fishes. The author who had the good
+fortune of examining this fish, was enabled to show that, on the one
+hand, it was a form most closely allied to <i>Lepidosiren</i>; on the
+other, that it could not be separated from the Ganoid fishes, and
+therefore that also <i>Lepidosiren</i> was a Ganoid: a relation pointed
+at already by Huxley in a previous paper on “Devonian Fishes.” This
+discovery led to further considerations<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">[3]</a> of the relative characters
+of Müller’s sub-classes, and to the system which is followed in the
+present work.</p>
+
+<p>Having followed the development of the ichthyological system down to
+the latest time, we have to retrace our steps to enumerate the most
+important contributions to Ichthyology which appeared contemporaneously
+with or subsequently to the publication of Cuvier and Valenciennes’s
+great work. As in other branches of Zoology, activity increased almost
+with every year; and for convenience’s sake we may arrange these works
+in three rubrics.</p>
+
+
+<div class="sidenote">Recent Works.</div>
+
+<h3>I.—<span class="smcap">Voyages, Containing General Accounts of Zoological
+Collections.</span></h3>
+
+
+<h4>A. <i>French.</i></h4>
+
+<p>1. “Voyage autour du monde sur les Corvettes de S. M. l’Uranie et la
+Physicienne, sous le commandement de M. Freycinet. Zoologie: Poissons
+par <i>Quoy</i> et <i>Gaimard</i>.” (Paris, 1824, 4to, atlas fol.)</p>
+
+<p>2. “Voyage de la Coquille. Zoologie par <i>Lesson</i>.” (Paris,
+1826–30, 4to, atlas fol.)</p>
+
+<p>3. “Voyage de l’Astrolabe, sous le commandement de M. J. Dumont
+d’Urville. Poissons par <i>Quoy</i> et <i>Gaimard</i>.” (Paris, 1834,
+8vo, atlas fol.)</p>
+
+<p><span class="pagenum" id="Page_27">[27]</span></p>
+
+<p>4. “Voyage au Pôle Sud par M. J. Dumont d’Urville. Poissons par
+<i>Hombron</i> et <i>Jacquinot</i>.” (Paris, 1853–4, 8vo, atlas fol.)</p>
+
+
+<h4>B. <i>English.</i></h4>
+
+<p>1. “Voyage of H.M.S. Sulphur. Fishes by <i>J. Richardson</i>.” (Lond.
+1844–5, 4to.)</p>
+
+<p>2. “Voyage of H.M.S.S. Erebus and Terror. Fishes by <i>J.
+Richardson</i>.” (Lond. 1846. 4to.)</p>
+
+<p>3. “Voyage of H.M.S. Beagle. Fishes by <i>L. Jenyns</i>.” (Lond. 1842,
+4to.)</p>
+
+<p>4. “Voyage of H.M.S. Challenger. Fishes by <i>A. Günther</i>.” (in
+course of publication).</p>
+
+
+<h4>C. <i>German.</i></h4>
+
+<p>1. “Reise der österreichischen Fregatte Novara. Fische von <i>R.
+Kner</i>.” (Wien. 1865, 4to.)</p>
+
+
+<h3>II.—<span class="smcap">Faunae.</span></h3>
+
+<h4>A. <i>Great Britain.</i></h4>
+
+<p>1. <i>R. Parnell</i>, “The Natural History of the Fishes of the Firth
+of Forth.” (Edinb. 1838, 8vo.)</p>
+
+<p>2. <i>W. Yarrell</i>, “A History of British Fishes.” (3d edit. Lond.
+1859, 8vo.)</p>
+
+<p>3. <i>J. Couch</i>, “A History of the Fishes of the British Islands.”
+(Lond. 1862–5, 8vo.)</p>
+
+
+<h4>B. <i>Denmark and Scandinavia.</i></h4>
+
+<p>1. <i>H. Kröyer</i>, “Danmark’s Fiske.” (Kjöbnh. 1838–53, 8vo.)</p>
+
+<p>2. <i>S. Nilsson</i>, “Skandinavisk Fauna.” (Vol. IV. Fiskarna. Lund.
+1855, 8vo.)</p>
+
+<p>3. <i>Fries och Ekström</i>, “Skandinavians Fiskar.” (Stockh. 1836,
+4to, with excellent plates.)</p>
+
+<p><span class="pagenum" id="Page_28">[28]</span></p>
+
+
+<h4>C. <i>Russia.</i></h4>
+
+<p>1. <i>Nordmann</i>, “Ichthyologie Pontique,” in “Voyage dans la Russie
+méridionale de <i>Demidoff</i>.” (Tom. iii. Paris, 1840, 8vo, atlas
+fol.)</p>
+
+
+<h4>D. <i>Germany.</i></h4>
+
+<p>1. <i>Heckel</i> and <i>Kner</i>, “Die Süsswasser-fische der
+Oesterreichischen Monarchie.” (Leipz. 1858, 8vo.)</p>
+
+<p>2. <i>C. T. E. Siebold</i>, “Die Süsswasser-fische von Mitteleuropa.”
+(Leipz. 1863, 8vo.)</p>
+
+
+<h4>E. <i>Italy and Mediterranean.</i></h4>
+
+<p>1. <i>Bonaparte</i>, “Iconografia della Fauna Italica.” Tom. iii.
+Pesci. (Roma, 1832–41, fol.) (Incomplete.)</p>
+
+<p>2. <i>Costa</i>, “Fauna del Regno di Napoli.” Pesci. (Napoli, 4to,
+about 1850.) (Incomplete.)</p>
+
+
+<h4>F. <i>France.</i></h4>
+
+<p>1. <i>E. Blanchard</i>, “Les Poissons des eaux douces de la France.”
+(Paris, 1866, 8vo.)</p>
+
+
+<h4>G. <i>Pyrenean Peninsula.</i></h4>
+
+<p>The freshwater Fish-fauna of Spain and Portugal was almost unknown,
+until <i>F. Steindachner</i> paid some visits to those countries for
+the purpose of exploring the principal rivers. His discoveries are
+described in several papers in the “Sitzungsberichte der Akademie zu
+Wien.” <i>B. du Bocage</i> and <i>F. Capello</i> contributed towards
+the knowledge of the marine fishes on the coast of Portugal. (“Jorn.
+Scienc. Acad. Lisb.”)</p>
+
+
+<h4>H. <i>North America.</i></h4>
+
+<p>1. <i>J. Richardson</i>, “Fauna Boreali Americana.” Part III. Fishes.
+(Lond. 1836, 4to.) The species described in this work are nearly all
+from the British possessions in the North.</p>
+
+<p><span class="pagenum" id="Page_29">[29]</span></p>
+
+<p>2. <i>Dekay</i>, “Zoology of New York.” Part IV. Fishes. (New York,
+1842, 4to.)</p>
+
+<p>3. “Reports of the United States Commission of Fish and Fisheries.”
+(5 vols. Washingt. 1873–79, 8vo. In progress. Contains most valuable
+information.)</p>
+
+<p>Besides these works, numerous descriptions of North American freshwater
+fishes have been published in the Reports of the various U. S.
+Government expeditions, and in North American scientific journals,
+by <i>Storer</i>, <i>Baird</i>, <i>Girard</i>, <i>W. O. Ayres</i>,
+<i>Cope</i>, <i>Jordan</i>, <i>Brown Goode</i>, etc.; but a good
+general, and especially critical, account of the fishes of the United
+States is still a desideratum.</p>
+
+
+<h4>I.—<i>Japan.</i></h4>
+
+<p>1. “Fauna Japonica.” Poissons par <i>H. Schlegel</i>. (Lugd. Bat. 1850,
+fol.)</p>
+
+
+<h4>J.—<i>East Indies; Tropical parts of the Indian and Pacific Oceans.</i></h4>
+
+<p>1. <i>E. Rüppell</i>, “Atlas zu der Reise im Nördlichen Afrika.”
+(Frankf. 1828, fol.)</p>
+
+<p>2. <i>E. Rüppell</i>, “Neue Wirbelthiere. Fische.” (Frankf. 1837, fol.)</p>
+
+<p>These two works form the standard works for the student of the Fishes
+of the Red Sea, and are distinguished by a rare conscientiousness and
+faithfulness of the descriptions and figures; so that there is no
+other part of the tropical seas, with the fishes of which we are so
+intimately acquainted, as with those of the Red Sea. But these works
+have a still wider range of usefulness, in as much as only a small
+proportion of the fishes is limited to that area, the majority being
+distributed over the Indian Ocean into Polynesia. Rüppel’s works were
+supplemented by the two first of the following works:—</p>
+
+<p>3. <i>R. L. Playfair</i> and <i>A. Günther</i>, “The Fishes of
+Zanzibar.” (Lond. 1866, 4to); and</p>
+
+<p><span class="pagenum" id="Page_30">[30]</span></p>
+
+<p>4. <i>C. B. Klunzinger</i>, “Synopsis der Fische des Rothen Meers.”
+(Wien. 1870–1, 8vo.)</p>
+
+<p>5. <i>T. Cantor</i>, “Catalogue of Malayan Fishes.” (Calcutta, 1850,
+8vo.)</p>
+
+<p>6. <i>F. Day</i>, “The Fishes of India.” (Lond. 1875, 4to, in
+progress); contains an account of the freshwater and marine species,
+and is not yet complete.</p>
+
+<p>7. <i>A. Günther</i>, “Die Fische der Südsee.” (Hamburg, 4to; from
+1873, in progress.)</p>
+
+<p>Unsurpassed in activity, as regards the exploration of the fish fauna
+of the East Indian Archipelago, is <i>P. Bleeker</i>, a surgeon in the
+service of the Dutch East Indian Government (born 1819, died 1878),
+who, from the year 1840, for nearly thirty years, amassed immense
+collections of the fishes of the various islands, and described them
+in extremely numerous papers, published chiefly in the Journals of the
+Batavian Society. When his descriptions and the arrangement of his
+materials evoked some criticism, it must be remembered that, at the
+time when he commenced his labours, and for many years afterwards,
+he stood alone, without the aid of a previously named collection on
+which to base his first researches, and without other works but that
+of Cuvier and Valenciennes. He had to create for himself a method of
+distinguishing species and of describing them; and afterwards it would
+have been difficult for him to abandon his original method and the
+principles by which he had been guided for so many years. His desire
+of giving a new name to every individual, to every small assemblage
+of species wherever practicable, or of changing an old name, detracts
+not a little from the satisfaction with which his works would be
+used otherwise. It is also surprising that a man with his anatomical
+knowledge and unusual facilities should have been satisfied with the
+merely external examination of the specimens. But none of his numerous
+articles contain anything<span class="pagenum" id="Page_31">[31]</span> relating to the anatomy, physiology, or
+habits of the fishes which came under his notice; hence his attempts
+at systematic arrangement are very far from indicating an advance in
+Ichthyology.</p>
+
+<p>Soon after his return to Europe (1860) Bleeker commenced to collect the
+final results of his labours in a grand work, illustrated by coloured
+plates, “Atlas Ichthyologique des Indes Orientales Néerlandaises.”
+(Amsterd. fol. 1862); the publication of which was interrupted by the
+author’s death in 1878.</p>
+
+
+<h4>K.—<i>Africa.</i></h4>
+
+<p>1. <i>A. Günther</i>, “The Fishes of the Nile” in Petherick’s “Travels
+in Central Africa.” (Lond. 1869, 8vo.)</p>
+
+<p>2. <i>W. Peters</i>, “Naturwissenschaftliche Reise nach Mossambique.
+IV. Flussfische.” (Berl. 1868, 4to.)</p>
+
+
+<h4>L.—<i>West Indies and South America.</i></h4>
+
+<p>1. <i>L. Agassiz</i>, “Selecta genera et species Piscium, quæ in
+itinere per Brasiliam, collegit J. B. de Spix.” (Monach. 1829, fol.)</p>
+
+<p>2. <i>F. de Castlenau</i>, “Animaux nouveaux ou rares, recueillis
+pendant l’expedition dans les parties centrales de l’Amérique du Sud.
+Poissons.” (Paris, 1855, 4to.)</p>
+
+<p>3. <i>A. Günther</i>, “An account of the Fishes of the States of
+Central America.” (In Trans. Zool. Soc. 1868.)</p>
+
+<p>4. <i>L. Vaillant</i> and <i>F. Bocourt</i>, “Mission scientifique au
+Mexique et dans l’Amérique centrale. Poissons.” (Paris, 1874, 4to.) (In
+progress.)</p>
+
+<p><i>F. Poey</i>, the celebrated naturalist of Havannah, devoted many
+years of study to the Fishes of Cuba, His papers and memoirs are
+published partly in two periodicals, issued by himself, under the
+title of “Memorias sobre la Historia natural de la Isle de Cuba” (from
+1851), and “Repertorio<span class="pagenum" id="Page_32">[32]</span> Fisico-natural de la Isla de Cuba” (from 1865),
+partly in North American scientific journals. And, finally, <i>F.
+Steindachner</i> has published many contributions, accompanied by
+excellent figures, to our knowledge of the Fishes of Central and South
+America.</p>
+
+
+<h4>M.—<i>New Zealand.</i></h4>
+
+<p>1. <i>F. W. Hutton</i> and <i>J. Hector</i>, “Fishes of New Zealand.”
+(Wellingt. 1872, 8vo.)</p>
+
+
+<h4>N.—<i>Arctic Regions.</i></h4>
+
+<p>1. <i>G. Lütken</i>, “A revised Catalogue of the Fishes of Greenland,”
+in “Manual of the Natural History, Geology, and Physics of Greenland.”
+(Lond. 1875, 8vo.) Although only a nominal list, this catalogue is
+useful, as it contains references to all the principal works in which
+Arctic fishes have been described. The fishes of Spitzbergen were
+examined by <i>A. J. Malmgren</i> (1865).</p>
+
+
+<h3>III.—<span class="smcap">Anatomical Works.</span></h3>
+
+<p>The number of authors who worked on the anatomy of fishes is almost
+as great as that of faunists; and we should go beyond the limits of
+the present work if we mentioned more than the most prominent and
+successful. <i>M. H. Rathke</i>, <i>J. Müller</i>, <i>J. Hyrtl</i>,
+and <i>H. Stannius</i> left scarcely any organ unexamined, and their
+researches had a direct bearing either on the relation of the class of
+fishes to the other vertebrates, or on the systematic arrangement of
+the fishes themselves. <i>E. E. von Baer</i>, <i>F. de Filippi</i>,
+<i>C. Vogt</i>, <i>W. His</i>, <i>W. K. Parker</i>, and <i>F. M.
+Balfour</i> worked at their embryology; <i>A. Kölliker</i> and <i>G.
+Pouchet</i> at their histology. The osteology was specially treated
+by <i>G. Bakker</i>, <i>F. C. Rosenthal</i>, <i>L. Agassiz</i>,
+and <i>C. Gegenbaur</i>; the nervous system by <i>Gottsche</i>,
+<i>Philipeaux</i>, <i>Stannius</i>, <i>L. de Sanctis</i>, <i>L.
+Stieda</i>, <i>Baudelot</i> and <i>Miclucho-Maclay</i>; the organ of
+hearing by <i>E. H. Weber</i>, <i>C. Hasse</i>, and <i>G. Retzius</i>.
+The electric fishes were examined by <i>E. Geoffroy</i>,<span class="pagenum" id="Page_33">[33]</span> <i>C.
+Matteuci</i>, <i>P. Pacini</i>, <i>T. Bilharz</i>, and <i>Max
+Schultze</i>. The development and metamorphosis of the Lamperns was
+made the subject of research by <i>H. Müller</i>, <i>M. Schultze</i>,
+and <i>P. Owsjannikow</i>; Müller’s examination of <i>Branchiostoma</i>
+was continued by <i>J. Marcusen</i>, <i>A. Kovalevsky</i>, <i>L.
+Stieda</i>, <i>W. Müller</i>, <i>C. Hasse</i>, <i>T. Huxley</i>, and
+<i>F. M. Balfour</i>. The most comprehensive accounts of the anatomy of
+fishes are contained in the following works:—</p>
+
+<p>1. <i>H. Stannius</i>, “Zootomic der Fische,” 2d edit. (Berl. 1854,
+8vo.)</p>
+
+<p>2. <i>R. Owen</i>, “Anatomy of Vertebrates,” vol. i. (Lond. 1866, 8vo.)</p>
+
+<p>3. <i>R. Owen</i>, “Lectures on the Comparative Anatomy and Physiology
+of the Vertebrate Animals.” Part I. Fishes. (Lond. 1846, 8vo.)</p>
+
+<p>4. <i>T. Huxley</i>, “A Manual of the Anatomy of Vertebrated Animals.”
+(Lond. 1871, 16mo.)</p>
+
+<hr class="tb">
+
+<div class="sidenote">Latest Systematic Works.</div>
+
+<p class="p-left">It has been mentioned above that the great work of Cuvier and
+Valenciennes had been left incomplete. Several authors, therefore,
+supplied detailed accounts of the orders omitted in that work.
+<i>Müller</i> and <i>Henle</i> published an account of the
+Plagiostomes, and <i>Kaup</i> of the Murænidæ and Lophobranchii. <i>A.
+Duméril</i>, finally, commenced an “Histoire naturelle des Poissons ou
+Ichthyologie générale,” of which, however, two volumes only appeared,
+containing a complete account of the “Plagiostomes” (Paris, 1865,
+8vo.), and of the “Ganoids and Lophobranchs.” (Paris, 1870, 8vo.)</p>
+
+<p>So great an activity had prevailed in Ichthyology since the publication
+of the “Histoire naturelle” by Cuvier and Valenciennes, and the results
+of the manifold enquiries were scattered over such a multitude of
+publications, that it became imperative to collect again all these
+materials in one comprehensive work. This was done in the “Catalogue
+of Fishes,”<span class="pagenum" id="Page_34">[34]</span> published by the Trustees of the British Museum, in eight
+volumes (Lond. 1859-70). Beside the species previously described
+many new forms were added, the number total of species referred
+to in those volumes amounting to 8525. As regards the systematic
+arrangement—Müller’s system was adopted in the main, but the
+definition of the families is much modified. This, however, need not be
+further entered into here, and will become sufficiently apparent in the
+subsequent parts of the present work.</p>
+
+  <div class="figcenter" id="fig1" style="max-width: 464px">
+     <img
+    class="p1"   
+    src="images/fig1.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 1.—Lower aspect of head of <i>Raia lemprieri</i>.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_35">[35]</span></p>
+
+<h2 class="smaller">CHAPTER II.<br>
+<span class="subhed">TOPOGRAPHICAL DESCRIPTION OF THE EXTERNAL PARTS OF FISHES.</span></h2></div>
+
+<div class="sidenote">Form of the body.</div>
+
+<p class="p-left">In the body of a fish four parts are distinguished: the <i>head</i>,
+<i>trunk</i>, <i>tail</i>, and the <i>fins</i>; the boundary
+between the first and second being generally indicated by the
+<i>gill-opening</i>, and that between the second and third by the
+<i>vent</i>. The form of the body and the relative proportions of those
+principal parts are subject to much variation, such as is not found in
+any other class of Vertebrates. In fishes which are endowed with the
+power of steady and more or less rapid locomotion, a deviation from
+that form of body, which we observe in a perch, carp, or mackerel,
+is never excessive. The body forms a simple, equally-formed wedge,
+compressed or slightly rounded, well fitted for cleaving the water.
+In fishes which are in the habit of moving on the bottom, the whole
+body, or at least the head, is <i>vertically depressed</i> and
+flattened; the head may be so enormously enlarged that the trunk and
+tail appear merely as an appendage. In one family of fishes, the
+<i>Pleuronectidæ</i> or Flat-fishes, the body is compressed into a thin
+disk; they swim and move on one side only, which remains constantly
+directed towards the bottom, a peculiarity by which the symmetry of
+all parts of the body has been affected. A <i>lateral compression</i>
+of the body, in conjunction with a lengthening of the vertical and
+a shortening of the longitudinal axis, we find in fishes moving
+comparatively slowly through<span class="pagenum" id="Page_36">[36]</span> the water, and able to remain (as it
+were) suspended in it. This deviation from the typical form may proceed
+so far that the vertical axis greatly exceeds the longitudinal in
+length; generally all the parts of the body participate in this form,
+but in one kind of fish (the Sun-fish or <i>Orthagoriscus</i>) it is
+chiefly the tail which has been shortened, and reduced so much as to
+present the appearance of being cut off. An excessive lengthening of
+the longitudinal axis, with a shortening of the vertical, occurs in
+Eels and eel-like fishes, and in the so-called Band-fishes. They are
+bottom-fish, capable of insinuating themselves into narrow crevices and
+holes. The form of the body of these long fish is either cylindrical,
+snake-like, as in the Eels and many Cod-fishes, or strongly compressed
+as in the Band-fishes (<i>Trichiurus</i>, <i>Regalecus</i>, etc.) It
+is chiefly the tail which is lengthened, but frequently the head and
+trunk participate more or less in this form. Every possible variation
+occurs between these and other principal types of form. The old
+ichthyologists, even down to Linnæus, depended in great measure on them
+for classification; but although often the same form of body obtains
+in the same group of fishes, similarity of form by no means indicates
+natural affinity; it only indicates similitude of habits and mode of
+life.</p>
+
+<div class="sidenote">Eye.</div>
+
+<p class="p-left"><i>The external parts of the Head.</i>—The <i>Eye</i> divides the head
+into the <i>ante-orbital</i> and <i>post-orbital</i> portion. In most
+fishes, especially in those with a compressed head, it is situated
+on the side and in the anterior half of the length of the head; in
+many, chiefly those with a depressed head, it is directed upwards, and
+sometimes situated quite at the upper side; in very few, the eyes look
+obliquely downwards. In the Flat-fishes both eyes are on the same side
+of the head, either the right or the left, always on that which is
+directed towards the light, and coloured.</p>
+
+<p>Fishes in general, compared with other Vertebrata, have large eyes.
+Sometimes these organs are enormously enlarged,<span class="pagenum" id="Page_37">[37]</span> their great size
+indicating that the fish is either nocturnal, or lives at a depth to
+which only a part of the sun’s rays penetrate. On the other hand, small
+eyes occur in fishes inhabiting muddy places, or great depths to which
+scarcely any light descends, or in fishes in which the want of an organ
+of sight is compensated by the development of other organs of sense.
+In a few fishes, more particularly in those inhabiting caves or the
+greatest depths of the ocean, the eyes have become quite rudimentary
+and hidden under the skin.</p>
+
+<div class="sidenote">Snout.</div>
+
+<p class="p-left">In the <i>ante-orbital</i> portion of the head, or the <i>Snout</i>,
+are situated the mouth and the nostrils.</p>
+
+<div class="sidenote">Mouth.</div>
+
+<p class="p-left">The <i>Mouth</i> is formed by the intermaxillary and maxillary
+bones, or by the intermaxillary only in the upper jaw, and by the
+mandibulary bone in the lower. These bones are either bare or covered
+by integument, to which frequently labial folds or lips are added.
+As regards form, the mouth offers as many variations as the body
+itself, in accordance with the nature of the food, and the mode of
+feeding. It may be narrow, or extremely wide and cleft to nearly the
+hind margin of the head; it may be semi-elliptical, semicircular, or
+straight in a transverse line; it may be quite in front of the snout
+(<i>anterior</i>), or at its upper surface (<i>superior</i>), or at its
+lower (<i>inferior</i>), or extending along each side <i>(lateral</i>);
+sometimes it is subcircular, organised for sucking. The jaws of some
+fishes are modified into a special weapon of attack (Sword-fish,
+Saw-fish); in fact, throughout the whole class of fishes the jaws are
+the only organ specialised for the purpose of attacking; weapons on
+other parts of the body are purely defensive.</p>
+
+<p>Both jaws may be provided with skinny appendages, <i>barbels</i>,
+which, if developed and movable, are sensitive organs of touch.</p>
+
+<div class="sidenote">Nostrils.</div>
+
+<p class="p-left">In the majority of fishes the <i>Nostrils</i> are a double opening on
+each side of the upper surface of the snout; the openings<span class="pagenum" id="Page_38">[38]</span> of each side
+being more or less close together. They lead into a shallow groove;
+and only in one family (the Myxinoids) perforate the palate. In this
+family, as well as in the Lampreys, the nasal aperture is single. In
+many Eels the openings are lateral, the lower perforating the upper
+lip. In the Sharks and Rays (Fig. <a href="#fig1">1</a>, p. 34) they are at the lower
+surface of the snout, and more or less confluent; and, finally, in the
+Dipnoi and other Ganoids, one at least is within the labial boundary of
+the mouth.</p>
+
+<p>The space across the forehead, between the orbits, is called
+the <i>interorbital</i> space; that below the orbit, the
+<i>infraorbital</i> or <i>sub-orbital</i> region.</p>
+
+<div class="sidenote">Gill-cover.</div>
+
+<p class="p-left">In the <i>post-orbital</i> part of the head there are distinguished,
+at least in most Teleosteous Fishes and many Ganoids, (Fig. <a href="#fig24">24</a>) the
+<i>præoperculum</i>, a sub-semicircular bone, generally with a free and
+often serrated or variously-armed margin; the <i>operculum</i>, forming
+the posterior margin of the gill-opening, and the <i>sub-operculum</i>
+and <i>interoperculum</i> along its inferior margin. All these bones,
+collectively called <i>opercles</i>, form the <i>gill-cover</i>, a
+thin bony lamella covering the cavity containing the gills. Sometimes
+they are covered with so thin a membrane that the single bones may
+be readily distinguished; sometimes they are hidden under a thick
+integument. In some cases the interoperculum is rudimentary or entirely
+absent (Siluroids).</p>
+
+<div class="sidenote">Gill-opening.</div>
+
+<p class="p-left">The <i>Gill-opening</i> is a foramen, or a slit behind or below
+the head, by which the water which has been taken up through the
+mouth for the purpose of breathing is again expelled. This slit may
+extend from the upper end of the operculum all round the side of
+the head to the symphysis of the lower jaw; or it may be shortened
+and finally reduced to a small opening on any part of the margin of
+the gill-cover. Sometimes (<i>Symbranchus</i>) the two openings,
+thus reduced, coalesce, and form what externally appears as a single
+opening only. The margin of the gill-cover is provided with a cutaneous
+fringe,<span class="pagenum" id="Page_39">[39]</span> in order to more effectually close the gill-opening; and
+this fringe is supported by one or several or many bony rays, the
+<i>branchiostegals</i>. The space on the chest between the two
+rami of the lower jaw and between the gill-openings is called the
+<i>isthmus</i>.</p>
+
+  <div class="figcenter" id="fig2" style="max-width: 600px">
+     <img
+    class="p1"   
+    src="images/fig2.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 2.—Head of <i>Mordacia mordax</i>, showing the
+single nostril, and seven branchial openings.</p>
+  </div>
+
+<p>The Sharks and Rays differ from the Teleosteous and Ganoid fishes in
+having five branchial slits (six or seven in <i>Hexanchus</i> and
+<i>Heptanchus</i>), which are lateral in the Sharks, and at the lower
+surface of the head in the Rays (Fig. <a href="#fig1">1</a>, p. 34). In Myxine only the
+gill-opening is at a great distance from the head; it is either single
+in this family (Cyclostomi), or there are six and more on each side
+(Fig. <a href="#fig2">2</a>).</p>
+
+<div class="sidenote">Tail.</div>
+
+<p class="p-left">In the <i>Trunk</i> are distinguished the <i>back</i>, the
+<i>sides</i>, and the <i>abdomen</i>. It gradually passes in all fishes
+into the <i>Tail</i>; the termination of the abdominal cavity and the
+commencement of the tail being generally indicated by the position
+of the vent. The exceptions are numerous: not only certain abdominal
+organs, like the sexual, may extend to between the muscles of the tail,
+but the intestinal tract itself may pass far backwards, or, singularly,
+it may be reflected forwards, so that the position of the vent may be
+either close to the extremity of the tail or to the foremost part of
+the trunk.</p>
+
+<p>In many fishes the greater part of the tail is surrounded by the
+fins, leaving only a small portion (between dorsal, caudal, and anal
+fins) finless; this part is called the <i>free portion</i> or the
+<i>peduncle</i> of the tail.</p>
+
+<p><span class="pagenum" id="Page_40">[40]</span></p>
+
+<div class="sidenote">Fins.</div>
+
+<p class="p-left">The <i>Fins</i> are divided into <i>vertical</i> or <i>unpaired</i>,
+and into <i>horizontal</i> or <i>paired fins</i>. Any of them may
+be present or absent; and their position, number, and form are most
+important guides in determining the affinities of fishes.</p>
+
+<p>The <i>vertical</i> fins are situated in the median dorsal line, from
+the head to the extremity of the tail, and in the ventral line of the
+tail. In fishes in which they are least developed or most embryonic,
+the vertical fin appears as a simple fold of the skin surrounding the
+extremity of the tail In its further progress of development in the
+series of fishes, it gradually extends more forwards, and may reach
+even the head and vent. Even in this embryonic condition the fin is
+generally supported by fine rays, which are the continuations of, or
+articulated to, other stronger rays supported by the processes or
+apophyses of the vertebral column. This form of the vertical fin is
+very common, for instance in the Eels, many Gadoid, Blennioid and
+Ganoid fishes in which, besides, the rays have ceased to be simple
+rods, showing more or less numerous joints (simple <i>articulated</i>
+rays; Fig. <a href="#fig3">3</a>). <i>Branched</i> rays are dichotomically split, the
+joints increasing in number towards the extremity.</p>
+
+<p>The continuity of the vertical fin, however, is interrupted in the
+majority of fishes; and three fins then are distinguished: one in the
+dorsal line—the <i>dorsal</i> fin; one in the ventral line behind the
+anus—the <i>anal</i> fin; and one confined to the extremity of the
+tail—the <i>caudal</i> fin.</p>
+
+  <div class="figcenter" id="fig3" style="max-width: 300px">
+     <img
+    class="p1"   
+    src="images/fig3.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 3.</p>
+<ul class="smaller left">
+  <li>1. Simple ray.</li>
+  <li>2. Spine.</li>
+  <li>3. Simple articulated ray (soft).</li>
+  <li>4. Branched ray (soft).]</li>
+</ul>
+  </div>
+
+<p>The <i>caudal</i> fin is rarely symmetrical, so that its upper
+half would be equal to its lower; the greatest degree of asymmetry
+obtains in fishes with heterocercal termination of the vertebral
+column (see subsequently, Figs. <a href="#fig31">31</a>, <a href="#fig41">41</a>). In fishes in<span class="pagenum" id="Page_41">[41]</span> which it is
+nearly symmetrical it is frequently prolonged into an upper and lower
+<i>lobe</i>, its hind margin being concave or more or less deeply
+excised; in others the hind margin is rounded, and when the middle rays
+greatly exceed in length the outer ones the fin assumes a pointed form.</p>
+
+  <div class="figcenter" id="fig4" style="max-width: 600px">
+     <img
+    class="p1"   
+    src="images/fig4.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 4.—Labrax lupus (Bass), an Acanthopterygian with
+anterior spinous, and posterior soft dorsal fin.</p>
+  </div>
+
+<p>Many and systematically important differences are observed in
+the <i>dorsal</i> fin, which is either spiny-rayed (spinous)
+(<i>Acanthopterygian</i>), or soft-rayed (<i>Malacopterygian</i>). In
+the former, a smaller or greater number of the rays are simple and
+without transverse joints; they may be flexible, or so much osseous
+matter is deposited in them that they appear hard and truly spinous
+(Fig. <a href="#fig3">3</a>); these spines form always the anterior portion of the fin,
+which is detached from, or continuous with, the remaining jointed rays.
+The spines can be erected or depressed at the will of the fish; if in
+the depressed position the spines cover one another completely, their
+points lying in the same line, the fish is called <i>homacanth</i>;
+but if the spines are asymmetrical, alternately broader on one side
+than on the other, the fish is called <i>heteracanth</i>. The spinous
+division, as well as the one consisting of jointed rays, may again be
+subdivided. In the <i>Malacopterygian</i> type all the rays remain
+jointed; indeed, sometimes the foremost ray, with its preceding short
+supports, is likewise ossified, and a hard spine, but the articulations
+can nearly always be distinctly<span class="pagenum" id="Page_42">[42]</span> traced. Sometimes the dorsal fin of
+Malacopterygian fishes is very long, extending from the head to the
+end of the tail, sometimes it is reduced to a few rays only, and in
+a few cases it is entirely absent. In addition to the rayed dorsal
+fin, many Malacopterygian fishes (as the Salmonoids, many Siluroids,
+Scopeloids, etc.) have another of greater or lesser extent, without any
+rays; and as always fat is deposited within this fold, it is called a
+<i>fatty</i> fin (<i>pinna adiposa</i>).</p>
+
+  <div class="figcenter" id="fig5" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig5.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 5.—Saurus undosquamis, a Malacopterygian with
+anterior soft dorsal, and additional adipose fin.</p>
+  </div>
+
+<p>The <i>anal</i> fin is built on the same plan as the dorsal, and
+may be single or plural, long or short, or entirely absent; in
+Acanthopterygians its foremost rays are frequently simple and spinous.</p>
+
+<p>The <i>horizontal</i> or <i>paired</i> fins consist of two pairs: the
+pectorals and ventrals.</p>
+
+<p>The <i>pectoral</i> fins (with their osseous supports) are the
+homologues of the anterior limbs of the higher Vertebrata. They are
+always inserted immediately behind the gill-opening; either symmetrical
+with a rounded posterior margin, or asymmetrical, with the upper rays
+longest and strongest; in Malacopterygians with a dorsal spine the
+upper pectoral ray is frequently developed into a similar defensive
+weapon.</p>
+
+<p>The <i>ventral</i> fins are the homologues of the hind-limbs, and
+inserted on the abdominal surface, either behind the pectorals
+(<i>Pisces</i> s. <i>Pinnæ abdominales</i>), or below them
+<i>(Pisces</i> s. <i>Pinnæ thoracicæ</i>), or in advance of them
+(<i>Pisces</i> s. <i>Pinnæ jugulares</i>). They are generally narrow,
+composed of a small number of<span class="pagenum" id="Page_43">[43]</span> rays, the outer of which is frequently
+osseous. In some small groups of fishes, like the Gobies, the fins
+coalesce and form a suctorial disk.</p>
+
+  <div class="figcenter" id="fig6" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig6.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 6.—Salmo salar (Salmon), with abdominal ventral fins.</p>
+  </div>
+
+  <div class="figcenter" id="fig7" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig7.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 7.—Mullus barbatus (Red Mullet), with thoracic
+ventral fins.</p>
+  </div>
+
+  <div class="figcenter" id="fig8" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig8.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 8.—Burbot (Lota vulgaris), with jugular ventral fins.</p>
+  </div>
+
+<p>For the definition of the smaller systematic groups, and the
+determination of species, the numbers of the spines and rays are
+generally of the greatest importance. This holds good, especially
+for the ventral rays, by the number of which<span class="pagenum" id="Page_44">[44]</span> the Acanthopterygian
+affinities of a fish can nearly always be determined. The numbers of
+the dorsal and anal rays generally correspond to the number of vertebræ
+in a certain portion of the spine, and are therefore constant specific,
+generic, or even family characters; but when their number is very
+great, a proportionally wide margin must be allowed for variation, and
+the taxinomic value of this character becomes uncertain. The numbers of
+the pectoral and caudal rays are rarely of any account.</p>
+
+<div class="sidenote">Function of the Fins.</div>
+
+<p class="p-left">The fins are organs of motion; but it is chiefly the tail and the
+caudal fin by which the fish impels itself forward. To execute
+energetic locomotion the tail and caudal fin are strongly bent,
+with rapidity, alternately towards the right and left; whilst a
+gentle motion forwards is effected by a simple undulating action of
+the caudal fin, the lobes of which act like the blades of a screw.
+Retrograde motions can be made by fish in an imperfect manner only,
+by forward-strokes of the pectoral fins. When the fish wants to
+turn towards the left, he gives a stroke of the tail towards the
+right, the right pectoral acting simultaneously, whilst the left
+remains ad-pressed to the body. Thus the pectoral fins assist in the
+progressive motions of the fish, but rather directing its course than
+acting as powerful propellers. The chief function of the paired fins is
+to maintain the balance of the fish in the water, which is always the
+most unsteady where there is no weight to sink it: when the pectoral
+of one side, or the pectoral and ventral of the same side are removed,
+the fish loses its balance and falls on the side opposite; when both
+pectorals are removed, the fish’s head sinks; on removal of the dorsal
+and anal fins the motion of the fish assumes a zig-zag course. A fish
+deprived of all fins, as well as a dead fish, floats with the belly
+upwards, the back being the heavier part of the body.</p>
+
+<p>In numerous groups of fishes which live in mud, or are enabled to pass
+a longer or shorter time in soil periodically<span class="pagenum" id="Page_45">[45]</span> dried and hardened
+during the hot season, forms occur entirely devoid of, or with only
+rudimentary, ventral fins (Cyprinodon, Ophiocephalidæ, Galaxiidæ,
+Siluridæ). The chief function of these fins being to balance the body
+of the fish whilst swimming, it is evident that in fishes moving during
+a great part of their life over swampy ground, or through more or less
+consistent mud, this function of the ventral fins ceases, and that
+nature can readily dispense with these organs altogether.</p>
+
+  <div class="figcenter" id="fig9" style="max-width: 363px">
+     <img
+    class="p1"   
+    src="images/fig9.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 9.—Ventrals of <i>Gobius</i>.</p>
+  </div>
+
+<p>In certain fishes the shape and function of the fins are considerably
+modified: thus, in the Rays, locomotion is almost entirely effected
+and regulated by the broad and expanded pectoral fins acting with an
+undulatory motion of their margins, similar to the undulations of the
+long vertical fins of the Flat-fishes; in many Blennies the ventral
+fins are adapted for walking on the sea-bottom; in some Gobioids
+(<i>Periophthalmus</i>), Trigloids, Scorpænioids, and Pediculati, the
+pectoral fins are perfect organs of walking; in the Gobies, Cyclopteri,
+and Discoboli the ventral fins are transformed into an adhesive disk,
+and finally in the Flying-fish, in which the pectorals act as a
+parachute. In the Eels and other snake-like fishes, the swimming as
+well as the gliding motions are effected by several curvatures of the
+body, alternate towards the right and left, resembling the locomotion
+of Snakes. In the <i>Syngnathi</i> (Pipe-fishes) and <i>Hippocampi</i>,
+whose body admits of but a slight degree of lateral curvature, and
+whose caudal fin is generally small, if present at all, locomotion is
+very limited, and almost wholly dependent on the action of the dorsal
+fin, which consists of a rapid undulating movement.</p>
+
+  <div class="figcenter" id="fig10" style="max-width: 333px">
+     <img
+    class="p1"   
+    src="images/fig10.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 10.—Cycloid scale of Gadopsis marmoratus (magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig11" style="max-width: 333px">
+     <img
+    class="p1"   
+    src="images/fig11.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 11.—Cycloid scale of Scopelus resplendens (magn.)</p>
+  </div>
+
+<div class="sidenote">Skin and Scales.</div>
+
+<p class="p-left">The <i>skin</i> of fishes is either covered with scales, or naked, or
+provided with more or less numerous scutes of various forms and sizes.
+Some parts, like the head and fins, are more<span class="pagenum" id="Page_46">[46]</span> frequently naked than
+scaly. All fishes provided with electric organs, the majority of Eels,
+and the Lampreys, are naked. <i>Scales</i> of fishes are very different
+from those of Reptiles; the latter being merely folds of the cutis,
+whilst the scales of fishes are distinct horny elements, developed
+in grooves or pockets of the skin, like hairs, nails, or feathers.
+Very small or rudimentary scales are extremely thin, homogeneous in
+structure, and more or less imbedded in the skin, and do not cover each
+other. When more developed, they are imbricated (arranged in the manner
+of tiles), with the posterior part extruded and free, the surface of
+the anterior portion being usually covered by the skin to a greater or
+less extent. On their surface (Figs. <a href="#fig10">10</a> and <a href="#fig11">11</a>) may be observed a very
+fine striation concentric and parallel to the margin, and coarser striæ
+radiating from a central point towards the hind margin. Scales without
+a covering of enamel, with an entire (not denticulated) posterior
+margin, and with a concentric striation, are called <i>Cycloid</i>
+scales. <i>Ctenoid</i> scales (Figs. <a href="#fig12">12–15</a>) are generally thicker,
+and provided with spinous teeth on the posterior edges of the layers
+of which the scale consists. In some species only the layer nearest
+to the margin is provided with denticulations (Fig. <a href="#fig14">14</a>). Scales, the
+free surface of which is spiny, and which have no denticulation on the
+margin, have been termed <i>Sparoid</i> scales; but their distinction
+from ctenoid scales is by no means sharp, and there are even
+intermediate<span class="pagenum" id="Page_47">[47]</span> forms between the cycloid and ctenoid types. Both kinds
+of scales may occur not only in species of the same genus of fishes,
+but in the same fish.</p>
+
+  <div class="figcenter" id="fig12" style="max-width: 299px">
+     <img
+    class="p1"   
+    src="images/fig12.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 12.—Ctenoid scale of Scatophagus multifasciatus (magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig13" style="max-width: 333px">
+     <img
+    class="p1"   
+    src="images/fig13.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 13.—Ctenoid scale of Platycephalus cirrhonasus (magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig14" style="max-width: 351px">
+     <img
+    class="p1"   
+    src="images/fig14.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 14.—Ctenoid scale of Gobius ommaturus (magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig15" style="max-width: 313px">
+     <img
+    class="p1"   
+    src="images/fig15.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 15.—Ctenoid scale of Lethrinus (magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig16" style="max-width: 170px">
+     <img
+    class="p1"   
+    src="images/fig16.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 16. Ganoid Scales.</p>
+  </div>
+
+<p><i>Ganoid</i> scales are hard and bony, covered with a layer of
+enamel; they are generally rhombic or quadrangular, rarely rounded and
+imbricate; and arranged in oblique rows, those of one row being linked
+together by an articulary process. This type of scales, common in
+fossil Ganoid fishes, occurs among recent fishes in <i>Lepidosteus</i>
+and <i>Polypterus</i> only.</p>
+
+<p><span class="pagenum" id="Page_48">[48]</span></p>
+
+<p>Finally, in Sharks, the Balistidæ, and others, true scales are absent
+and replaced by the ossified papillæ of the cutis, which give the
+surface the appearance of fine-grained chagreen. These generally small
+bodies, as well as the large osseous scutes of the Rays, Sturgeons,
+etc., have been comprised under the common name <i>Placoid</i> scales;
+a term which deservedly is being abandoned.</p>
+
+  <div class="figcenter" id="fig17" style="max-width: 500px">
+     <img
+    class="p1"   
+    src="images/fig17.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 17.—Dermal papillæ of Monacanthus trossulus.</p>
+  </div>
+
+  <div class="figcenter" id="fig18" style="max-width: 500px">
+     <img
+    class="p1"   
+    src="images/fig18.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 18.—Dermal papillæ of Monacanthus hippocrepis (magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig19" style="max-width: 469px">
+     <img
+    class="p1"   
+    src="images/fig19.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 19.—Cycloid scale from the lateral line of Odax
+lineatus (magn.)</p>
+  </div>
+
+<p>Along the side of the body of osseous fishes runs a series of
+perforated scales, which is called the <i>lateral line</i> (Fig. <a href="#fig21">21</a>).
+The perforating duct is simple at its base, and may be also simple at
+its outer opening (Fig. <a href="#fig19">19</a>), or (and this is frequently the case) the
+portion on the free surface of the scale is ramified (Fig. <a href="#fig20">20</a>). The
+lateral line runs from the head to the tail, sometimes reaching the
+caudal fin, sometimes stopping in front of it, sometimes advancing over
+its rays. It is nearer to the dorsal profile in some fishes than in
+others. Some species have several lateral lines, the upper one coasting
+the dorsal, the lower the abdominal outline, one running along the
+middle as usual.<span class="pagenum" id="Page_49">[49]</span> The scales of the lateral line are sometimes larger
+than the others, sometimes smaller, sometimes modified into scutes,
+sometimes there are no other scales beside them, the rest of the body
+being naked. The foramina of the lateral line are the outlets of a
+muciferous duct which is continued on to the head, running along the
+infraorbital bones, and sending off a branch into the præopercular
+margin and mandible. In many fishes, as in many Sciænoids, Gadoids,
+and in numerous deep-sea fishes, the ducts of this muciferous system
+are extraordinarily wide, and generally filled with mucus, which
+is congealed or contracted in specimens preserved in spirits, but
+swells again when the specimens are immersed in water. This system is
+abundantly provided with nerves, and, therefore, has been considered
+to be the seat of a sense peculiar to fishes, but there cannot be any
+doubt that its function is the excretion of mucus, although probably
+mucus is excreted also from the entire surface of the fish.</p>
+
+  <div class="figcenter" id="fig20" style="max-width: 491px">
+     <img
+    class="p1"   
+    src="images/fig20.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 20.—Cycloid scale from the lateral line of
+Labrichthys laticlavius (magn.)</p>
+  </div>
+
+<p>The scales, their structure, number and arrangement, are an important
+character for the determination of fishes; in most scaly fishes they
+are arranged in oblique transverse series; and as the number of scales
+in the lateral line generally corresponds to the number of transverse
+series, it is usual to count the scales in that line. To ascertain
+the number of longitudinal series of scales, the scales are counted
+in one of<span class="pagenum" id="Page_50">[50]</span> the transverse series, generally in that running from the
+commencement of the dorsal fin, or the middle of the back to the
+lateral line, and from the lateral line down to the vent or ventral
+fin, or middle of the abdomen.<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">[4]</a></p>
+
+  <div class="figcenter" id="fig21" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig21.jpg"
+     alt="">
+     <p class="p0 p-left hangingindent smaller">Fig. 21.—Arrangement of scales in the Roach (Leuciscus
+ratilus): <i>Ll</i> = Lateral line; <i>tr</i> = Transverse line.
+<i>a</i>, Transverse line from lateral line to ventral fin.</p>
+  </div>
+
+<p>The scales of many fishes are modified for special purposes, especially
+to form weapons of defence or a protective armour, but the details of
+such modifications are better mentioned under the several families in
+which they occur. All scales are continually growing and wasting away
+on the surface, and it seems that some fish, at least,—for instance,
+Salmonoids—“shed” them periodically; during the progress of this
+shedding the outlines of the scales are singularly irregular.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_51">[51]</span></p>
+
+<h2 class="smaller">CHAPTER III.<br>
+<span class="subhed">TERMINOLOGY AND TOPOGRAPHY OF THE SKELETON.</span></h2></div>
+
+<p>In order to readily comprehend the subsequent account of the
+modifications of the skeleton in the various sub-classes and groups of
+Fishes, the student has to acquaint himself with the terms used for the
+numerous bones of the fish skeleton, as well as with their relative
+position. The skeleton of any of the more common kinds of osseous fish
+may serve for this purpose; that of the Perch is chosen here.</p>
+
+<p>The series of bones constituting the axis of the body, and destined to
+protect the spinal chord and some large longitudinal blood-vessels,
+is called the <i>vertebral</i> or <i>spinal column</i>; the single
+bones are the <i>vertebræ</i>. The <i>skull</i> consists of the bones
+surrounding the brain and organs of sense, and of a number of arches
+suspended from it, to support the commencement of the alimentary canal
+and the respiratory organs.</p>
+
+<p>The <i>vertebra</i> (Fig. <a href="#fig22">22</a>) consists of a body or <i>centrum</i>
+(<i>c</i>), with a concave anterior and posterior surface, and
+generally of several <i>processes</i> or <i>apophyses</i>, as—1.
+Two <i>neurapophyses</i> (<i>na</i>), which, on the dorsal side,
+rising upwards, form the <i>neural arch</i> over the canal, in which
+the spinal chord is lodged. 2. Two <i>parapophyses</i> (<i>pa</i>)
+usually projecting from the lower part of the sides of the body,
+or two <i>hæmapophyses</i> (<i>ha</i>) which actually coalesce to
+form on the ventral side the hæmal canal for a large trunk of the
+vascular system.<span class="pagenum" id="Page_52">[52]</span> 3. A <i>neural spine</i> (<i>ns</i>), which crowns
+the neurapophyses, or is interposed between their tips. 4. A <i>hæmal
+spine</i> (<i>hs</i>), having the same relation to the hæmapophyses.
+5. Two <i>pleurapophyses</i> or floating <i>ribs</i>, suspended from,
+or from the base of, the parapophyses. 6. In most fishes the neural
+arches are connected together by articular or oblique processes,
+<i>zygapophyses</i> (<i>za</i>), which are developed from the base of
+each neurapophysis.</p>
+
+  <div class="figcenter" id="fig22" style="max-width: 413px">
+     <img
+    class="p1"   
+    src="images/fig22.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 22.—Side and Front view of Fish-vertebra.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_53">[53]</span></p>
+
+<p>The vertebræ are either <i>abdominal</i> or <i>caudal</i> vertebræ, the
+coalescence of the parapophyses into a complete hæmal ring, and the
+suspension of the anal fin generally forming a sufficiently well-marked
+boundary between abdominal and caudal regions (Fig. <a href="#fig23">23</a>). In the Perch
+there are twenty-one abdominal and as many caudal vertebræ. The centrum
+of the first vertebra or atlas is very short, with the apophyses
+scarcely indicated, and lacking ribs like the succeeding vertebra. All
+the other abdominal vertebræ, with the exception of the last or two
+last, are provided with ribs, many of which are bifid (72). A series of
+flat spines (74), called <i>interneurals</i>, to which the spines and
+rays of the dorsal fins are articulated, are supported by the neural
+spines, the strength of the neurals and interneurals corresponding
+to that of the <i>dermal</i> spines (75). The caudal vertebræ differ
+from the abdominal in having the hæmapophyseal elements converted into
+spines similar to the neurals, the anterior being likewise destined to
+support a series of <i>interhæmals</i> (79), to which the anal rays are
+articulated. The last and smallest caudal vertebra articulates with the
+<i>hypural</i> (70), a fan-like bone, which, together with the dilated
+hindmost neural and hæmal elements, supports the caudal rays.</p>
+
+<p>Looking at a perch’s <i>skull</i> from the side (Fig. <a href="#fig24">24</a>), the most
+superficial bones will be found to be those of the jaws, a chain of
+thin bones round the lower half of the eye, and the opercles.</p>
+
+<p>The anterior margin of the upper jaw is formed by the
+<i>intermaxillary</i> or <i>premaxillary</i> (17) which bears teeth,
+terminates in a pedicle above, to allow of a forward sliding motion of
+the jaw, and is dilated into a flat triangular process behind, on which
+leans the second bone of the upper jaw, the <i>maxillary</i> (18). This
+bone is toothless, articulates with the vomer and palatine bone, and is
+greatly dilated towards its distal<span class="pagenum" id="Page_54">[54]</span> extremity. Both the maxillary and
+intermaxillary lie and move parallel to each other, being connected by
+a narrow membrane; in many other fishes their relative position is very
+different.</p>
+
+<p>The <i>mandible</i> or lower jaw consists of a right and left ramus;
+their union by a ligament in front is called <i>symphysis</i>. Each
+ramus is formed of several pieces; that which, by a sigmoid concavity
+articulates with the quadrate, is the <i>articulary</i> bone (35);
+it sends upwards a coronoid process, to which a ligament from the
+maxillary and the masticatory muscles are attached; and forwards a
+long-pointed process, to be sheathed in the deep notch of the anterior
+piece. A small separate piece (36) at the lower posterior angle of
+the mandible is termed <i>angular</i>. The largest piece (34) is
+tooth-bearing, and hence termed <i>dentary</i>; at its inner surface it
+is always deeply excavated, to receive a cylindrical cartilage, called
+<i>Meckel’s cartilage</i>, the remains of an embryonic condition of
+the jaw, the articulary and angular being but ossified parts of it.
+In other <i>Teleostei</i> this number is still more increased by a
+<i>splenial</i> and other bones.</p>
+
+<p>The <i>infraorbital</i> ring of bones (Fig. <a href="#fig23">23</a>, <sup>19</sup>) consists of
+several (four) pieces, of which the anterior is the largest, and
+distinguished as <i>præorbital</i>.</p>
+
+<p>The so-called <i>præoperculum</i> (30) belongs rather to the bones of
+the suspensorium of the mandible, presently to be described, than to
+the opercles proper. It is narrow, strong, angularly bent, so as to
+consist of a vertical and horizontal limb, with an incompletely closed
+canal running along both limbs. As it is quite a superficial bone, and
+frequently armed with various spines, its form and configuration form
+an important item in the descriptive details of many fishes.</p>
+
+<p>The principal piece of the gill-cover is the <i>operculum</i> (28),
+triangular in shape, situated behind, and movably united with, the
+vertical limb of the præoperculum. There is an<span class="pagenum" id="Page_55">[55]</span> articulary cavity at
+its upper anterior angle for its junction with the hyomandibular. The
+oblong lamella below the operculum is the <i>sub-operculum</i> (32),
+and the one in front of this latter, below the horizontal limb of the
+præoperculum, is the <i>interoperculum</i> (33), which is connected by
+ligament with the angular piece of the lower jaw, and is also attached
+to the outer face of the hyoid, so that the gill-covers cannot open or
+shut without the hyoid apparatus executing a corresponding movement.</p>
+
+<p>The chain of flat bones which, after the removal of the temporal
+muscles, appear arranged within the inner concavity of the præoperculum
+(Fig. <a href="#fig24">24</a>), are comprised with the latter under the common name of
+<i>mandibulary suspensorium</i>. They connect the mandible with the
+cranium. The uppermost, the <i>epitympanic</i> or <i>hyomandibular</i>
+(23), is articulated by a double articulary head with the mastoid
+and posterior frontal. Another articulary head is destined for
+the opercular joint. The <i>mesotympanic</i> or <i>symplectic</i>
+(31) appears as a styliform prolongation of the lower part of the
+hyomandibular; is entirely cartilaginous in the young, but nearly
+entirely ossified in the adult. The position of this bone is
+noteworthy, because, directly inwards of its cartilaginous junction
+with the hyomandibular, there is situated the uppermost piece of
+the hyoid arch, the stylohyal. The next bone of the series is the
+<i>pretympanic</i> or <i>metapterygoid</i> (27), a flat bone forming a
+bridge towards the pterygoid, and not rarely absent in the teleosteous
+sub-class. Finally, the large triangular <i>hypo-tympanic</i> or
+<i>quadrate</i> (26) has a large condyle for the mandibulary joint.</p>
+
+<p>The palatine arch (Fig. <a href="#fig26">26</a>) connects the suspensorium with the
+anterior extremity of the skull, and is formed by three bones: the
+<i>entopterygoid</i> (25), an oblong and thin bone attached to the
+inner border of the palatine and pterygoid, and increasing the surface
+of the bony roof of the mouth towards the<span class="pagenum" id="Page_56">[56]</span> median line; it constitutes
+also the floor of the orbit. The <i>pterygoid</i> (24) (or <i>os
+transversum</i>) starts from the quadrate, and is joined by suture to
+the <i>palatine</i>, which is toothed, and reaches to the vomer and
+anterior frontal.</p>
+
+<p>In the occipital region there are distinguished the
+<i>basi-occipital</i> (5), readily recognised by the conical
+excavation corresponding and similar to that of the atlas, with
+which it is articulated through the intervention of a capsule filled
+with a gelatinous substance (the remains of the notochord); the
+<i>exoccipitals</i> (10), articulated, one on each side, to the
+basi-occipital, and expanding on the upper surface of that bone, so as
+to meet and support the spinal column; a superficial thin lamella (13),
+suturally connected with the exoccipitals, not constant in fishes,
+and erroneously believed by Cuvier to be the <i>petrosal</i> (<i>os
+petrosum</i>) of higher animals; further, the <i>paroccipitals</i> (9),
+which are wedged in between the exoccipitals and <i>supraoccipital</i>.
+This last bone (8) forms the key of the arch over the occipital
+foramen, and raises a strong high crest from the whole length of its
+mesial line; a transverse supraoccipital ridge, coming from each side
+of the base of this spine runs outwards laterally to the external
+angles of the bone. The supraoccipital separates the parietals, and
+forms a suture with the frontals.</p>
+
+<p>In front of the basi-occipital the base of the skull is formed by
+the <i>basisphenoid</i> (<i>parasphenoid</i> of Huxley) (6). This
+very long and narrow bone extends from the basi-occipital beyond the
+brain-capsule to between the orbits, where it forms the support of the
+fibro-membranous interorbital septum. Anteriorly it is connate with
+another long hammer-shaped bone (16), the <i>vomer</i>, the head of
+which marks the anterior end of the palate, and is beset with teeth.
+The <i>alisphenoids</i> (11) are short broad bones, rising from the
+basisphenoid; their posterior margins are suturally connected with the
+anterior of the basi- and exoccipitals.</p>
+
+  <div class="figcenter" id="fig23" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig23.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 23.—Skeleton of the Perch.</p>
+  </div>
+
+  <div class="figcenter" id="fig24" style="max-width: 732px">
+     <img
+    class="p1"   
+    src="images/fig24.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 24.—Skeleton of a Perch’s Skull.</p>
+  </div>
+
+  <div class="figcenter" id="fig25" style="max-width: 660px">
+     <img
+    class="p1"   
+    src="images/fig25.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 25.—Hyoid arch, branchial apparatus, and scapulary
+arch of the Perch.</p>
+  </div>
+
+  <div class="figcenter" id="fig26" style="max-width: 449px">
+     <img
+    class="p1"   
+    src="images/fig26.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 26.—Lower view of Skull of Perch.</p>
+  </div>
+
+  <div class="figcenter" id="fig27" style="max-width: 423px">
+     <img
+    class="p1"   
+    src="images/fig27.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 27.—Hyoid bone of the Perch.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_57">[57]</span></p>
+
+<p>The formation of the posterior part of the side of the skull is
+completed by the <i>mastoid</i> and <i>parietal</i> bones. The former
+(12) projects outwards and backwards farther than the paroccipital,
+forming the outer strong process of the side of the cranium. This
+process lodges on its upper surface one of the main ducts of the
+muciferous system, and affords the base of articulation to a part of
+the hyomandibular. Its extremity gives attachment to the strong tendon
+of the dorso-lateral muscles of the trunk. The <i>parietals</i> (7)
+are flat bones, of comparatively much smaller extent than in higher
+Vertebrates, and separated from each other by the anterior prolongation
+of the supraoccipital.</p>
+
+<p>The anterior wall of the brain-capsule (or the posterior of the
+orbit) is formed by the <i>orbitosphenoids</i> (14), between which,
+superiorly, the olfactory nerves, and inferiorly, the optic, pass out
+of the cranium. In addition to this paired bone, the Perch and many
+other fishes possess another single bone (15),—the <i>os sphenoideum
+anterius</i> of Cuvier, <i>ethmoid</i> of Owen, and <i>basisphenoid</i>
+of Huxley; it is Y-shaped, each lateral branch being connected with an
+orbito-sphenoid, whilst the lower branch rests upon the long basal bone.</p>
+
+<p>A cartilage, the substance of which is thickest above the vomer,
+and which extends as a narrow stripe along the interorbital septum,
+represents the <i>ethmoid</i> of higher Vertebrata; the olfactory
+nerves run along, and finally perforate it.</p>
+
+<p>There remain, finally, the bones distinguishable on the upper surface
+of the skull; the largest, extending from the nasal cavities to the
+occipital, are the <i>frontal</i> bones (1), which also form the upper
+margin of the orbit. The <i>postfrontals</i> (4) are small bones placed
+on the supero-posterior angle of the orbit, and serving as the point
+from which the infraorbital ring is suspended. The <i>pre-frontals</i>
+(2), also small, occupy the anterior margin of the orbit. A pair of
+small tubiform bones (20), the <i>turbinals</i>, occupy the foremost
+part of the snout, in front of<span class="pagenum" id="Page_58">[58]</span> the frontals, and are separated from
+each other by intervening cartilage.</p>
+
+<p>After removal of the gill-cover and mandibulary suspensorium, the hyoid
+arch, which encloses the branchial apparatus, and farther behind,
+the humeral arch are laid open to view (Fig. <a href="#fig25">25</a>). These parts can be
+readily separated from the cranium proper.</p>
+
+<p>The <i>hyoid arch</i> is suspended by a slender styliform bone, the
+<i>stylohyal</i> (29), from the hyomandibulars; it consists of three
+segments, the <i>epihyal</i> (37), <i>ceratohyal</i> (38), which is
+the longest and strongest piece, and the <i>basihyal</i>, which is
+formed by two juxtaposed pieces (39, 40). Between the latter there is
+a median styliform ossicle (41), extending forwards into the substance
+of the tongue, called <i>glossohyal</i> or <i>os linguale</i>; and
+below the junction of the two hyoid branches there is a vertical
+single bone (42), expanded along its lower edge, which, connected by
+ligament with the anterior extremity of the humeral arch, forms the
+<i>isthmus</i> separating the two gill-openings. This bone is called
+the <i>urohyal</i>. Articulated or attached by ligaments to the epihyal
+and ceratohyal are a number of sword-shaped bones or rays (43), the
+<i>branchiostegals</i>, between which the branchiostegal membrane is
+extended.</p>
+
+<p>The <i>branchial arches</i> (Figs. <a href="#fig25">25</a> and <a href="#fig27">27</a>) are enclosed within
+the hyoid arch, with which they are closely connected at the base.
+They are five in number, of which four bear gills, whilst the fifth
+(56) remains dwarfed, is beset with teeth, and called the <i>lower
+pharyngeal</i> bone. The arches adhere by their lower extremities to
+a chain of ossicles (53, 54, 55), <i>basibranchials</i>, and, curving
+as they ascend, nearly meet at the base of the cranium, to which they
+are attached by a layer of ligamentous and cellular tissue. Each of the
+first three branchial arches consists of four pieces movably connected
+with one another. The lowest is the <i>hypobranchial</i> (57), the
+next much longer one (58) the <i>cerato-branchial</i>, and, above
+this, a slender and a short<span class="pagenum" id="Page_59">[59]</span> irregularly-shaped <i>epibranchial</i>
+(61). In the fourth arch the hypobranchial is absent. The uppermost
+of these segments (62), especially of the fourth arch, are dilated,
+and more or less confluent; they are beset with fine teeth, and
+generally distinguished as the <i>upper pharyngeal bones</i>. Only the
+cerato-branchial is represented in the fifth arch or lower pharyngeal.
+On their outer convex side the branchial segments are grooved for the
+reception of large blood-vessels and nerves; on the inner side they
+support horny processes (63), called the <i>gill-rakers</i>, which do
+not form part of the skeleton.</p>
+
+<p>The <i>scapular</i> or <i>humeral arch</i> is suspended from the
+skull by the (<i>suprascapula</i>) <i>post-temporal</i> (46), which,
+in the Perch, is attached by a triple prong to the occipital and
+mastoid bones. Then follows the (<i>scapula</i>) <i>supraclavicula</i>
+(47), and the arch is completed below by the union of the large
+(<i>coracoid</i>) <i>clavicula</i> (48) with its fellow. Two flat bones
+(51, 52), each with a vacuity, attached to the clavicle have been
+determined as the (<i>radius</i> and <i>ulna</i>) <i>coracoid</i> and
+<i>scapula</i> of higher vertebrates, and the two series of small bones
+(53) intervening between the forearm and the fin as <i>carpals</i> and
+<i>metacarpals</i>. A two-jointed appendage the (<i>epicoracoid</i>)
+<i>postclavicula</i>, is attached to the clavicle: its upper piece (49)
+is broad and lamelliform, its lower (50) styliform and pointed.</p>
+
+<p>The ventral fins are articulated to a pair of flat triangular bones,
+the <i>pubic</i> bones (80).</p>
+
+<p>The bones of the skull of the fish have received so many different
+interpretations that no two accounts agree in their nomenclature,
+so that their study is a matter of considerable difficulty to the
+beginner. The following synonymic table will tend to overcome
+difficulties arising from this cause; it contains the terms used
+by Cuvier, those introduced by Owen, and finally the nomenclature
+of Stannius, Huxley, and Parker. Those adopted in the present work
+are printed in italics. The<span class="pagenum" id="Page_60">[60]</span> numbers refer to the figures in the
+accompanying woodcuts (Figs. <a href="#fig23">23–27</a>).</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="chn"></td>
+    <td class="brckt"></td>
+    <td class="ctr"><i>Cuvier.</i></td>
+    <td class="ctr1"><i>Owen.</i></td>
+    <td class="brckt"></td>
+    <td class="ctr"><i>Stannius.</i></td>
+    <td class="brckt"></td>
+    <td class="ctr"><i>Huxley, Parker, etc.</i></td>
+  </tr>
+
+  <tr>
+    <td class="chn">1.</td>
+    <td class="brckt"></td>
+    <td class="cht">Frontal principal</td>
+    <td class="cht5"><i>Frontal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os frontale</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">2.</td>
+    <td class="brckt"></td>
+    <td class="cht">Frontal antérieur</td>
+    <td class="cht5"><i>Prefrontal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os frontale anterius</td>
+    <td class="brckt"></td>
+    <td class="cht">Lateral ethmoid (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">3.</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Ethmoid</i></td>
+    <td class="cht5">Nasal</td>
+    <td class="brckt"></td>
+    <td class="cht"> Os ethmoideum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">4.</td>
+    <td class="brckt"></td>
+    <td class="cht">Frontal postérieur</td>
+    <td class="cht5"><i>Postfrontal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os frontale posterius</td>
+    <td class="brckt"></td>
+    <td class="cht">Sphenotic  (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">5.</td>
+    <td class="brckt"></td>
+    <td class="cht">Basilaire</td>
+    <td class="cht5"><i>Basioccipital</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os basilare</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">6.</td>
+    <td class="brckt"></td>
+    <td class="cht">Sphénoide</td>
+    <td class="cht5"><i>Basisphenoid</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os sphenoideum basilare</td>
+    <td class="brckt"></td>
+    <td class="cht">Sometimes referred to as “<i>Basal</i>”</td>
+  </tr>
+
+  <tr>
+    <td class="chn">7.</td>
+    <td class="brckt"></td>
+    <td class="cht">Pariétal</td>
+    <td class="cht5"><i>Parietal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os parietale</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">8.</td>
+    <td class="brckt"></td>
+    <td class="cht">Interpariétal or occipital supérieure</td>
+    <td class="cht5"><i>Supraoccipital</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os occipitale superius</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">9.</td>
+    <td class="brckt"></td>
+    <td class="cht">Occipital externe</td>
+    <td class="cht5"><i>Paroccipital</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os occipitale externum</td>
+    <td class="brckt"></td>
+    <td class="cht">Epioticum (Huxley)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">10.</td>
+    <td class="brckt"></td>
+    <td class="cht">Occipital lateral</td>
+    <td class="cht5"><i>Exoccipital</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os occipitale laterale</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">11.</td>
+    <td class="brckt"></td>
+    <td class="cht">Grande aile du sphénoide</td>
+    <td class="cht5"><i>Alisphenoid</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Ala temporalis</td>
+    <td class="brckt"></td>
+    <td class="cht">Prooticum (<i>Huxley</i>)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">12.</td>
+    <td class="brckt"></td>
+    <td class="cht">Mastoidien</td>
+    <td class="cht5"><i>Mastoid</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os mastoideum + os extrascapulare</td>
+    <td class="brckt" rowspan="2"><img src="images/big_left_bracket.png"
+ alt="big left bracket"  style="height:4.5em; padding:0 1em 0 1em;"></td> 
+    <td class="cht6">Opisthoticum<a id="FNanchor_5" href="#Footnote_5" class="fnanchor">[5]</a>
+                    +<i>Squamosal</i> (Huxley)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">13.</td>
+    <td class="brckt"></td>
+    <td class="cht">Rocher</td>
+    <td class="cht5">Petrosal and Otosteal</td>
+    <td class="brckt"></td>
+    <td class="cht">Oberflächliche Knochen-lamelle</td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">14.</td>
+    <td class="brckt"></td>
+    <td class="cht">Aile orbitaire</td>
+    <td class="cht5"><i>Orbitosphenoid</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Ala orbitalis</td>
+    <td class="brckt"></td>
+    <td class="cht">Alisphenoid (Huxley)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">15.</td>
+    <td class="brckt"></td>
+    <td class="cht">Sphenoide antérieur</td>
+    <td class="cht5">Ethmoid and Ethmoturbinal</td>
+    <td class="brckt"></td>
+    <td class="cht">Os sphenoideum anterius</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Basisphenoid</i> (Huxley)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">16.</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Vomer</i></td>
+    <td class="cht5">Vomer</td>
+    <td class="brckt"></td>
+    <td class="cht">Vomer</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">17.</td>
+    <td class="brckt"></td>
+    <td class="cht">Intermaxillaire</td>
+    <td class="cht5"><i>Inter- or Pre-maxillary</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os intermaxillare</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">18.</td>
+    <td class="brckt"></td>
+    <td class="cht">Maxillaire supérieur</td>
+    <td class="cht5"><i>Maxillary</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os maxillare</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">19.</td>
+    <td class="brckt"></td>
+    <td class="cht">Sousorbitaires</td>
+    <td class="cht5"><i>Infraorbital ring</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Ossa infraorbitalia</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">20.</td>
+    <td class="brckt"></td>
+    <td class="cht">Nasal</td>
+    <td class="cht5"><i>Turbinal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os terminale</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">22.</td>
+    <td class="brckt"></td>
+    <td class="cht">Palatine</td>
+    <td class="cht5"><i>Palatin</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os palatinum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">23.</td>
+    <td class="brckt"></td>
+    <td class="cht">Temporal</td>
+    <td class="cht5">Epitympanic</td>
+    <td class="brckt"></td>
+    <td class="cht">Os temporale</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Hyomandibular</i> (Huxley)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">24.</td>
+    <td class="brckt"></td>
+    <td class="cht">Transverse</td>
+    <td class="cht5"><i>Pterygoid</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os transversum s. pterygoideum externum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">25.</td>
+    <td class="brckt"></td>
+    <td class="cht">Ptérygoidien interne</td>
+    <td class="cht5"><i>Entopterygoid</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os pterygoideum</td>
+    <td class="brckt"></td>
+    <td class="cht">Mesopterygoid (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">26.</td>
+    <td class="brckt"></td>
+    <td class="cht">Jugal</td>
+    <td class="cht5">Hypotympanic</td>
+    <td class="brckt"></td>
+    <td class="cht">Os quadratojugale</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Quadrate</i> (Huxley)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">27.</td>
+    <td class="brckt"></td>
+    <td class="cht">Tympanal</td>
+    <td class="cht5">Pretympanic</td>
+    <td class="brckt"></td>
+    <td class="cht">Os tympanicum</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Metapterygoid</i> (Huxley)<span class="pagenum" id="Page_61">[61]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chn">28.</td>
+    <td class="brckt"></td>
+    <td class="cht">Operculaire</td>
+    <td class="cht5"><i>Operculum</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Operculum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">29.</td>
+    <td class="brckt"></td>
+    <td class="cht">Styloide</td>
+    <td class="cht5"><i>Stylohyal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os styloideum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">30.</td>
+    <td class="brckt"></td>
+    <td class="cht">Préopercule</td>
+    <td class="cht5"><i>Præoperculum</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Præoperculum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">31.</td>
+    <td class="brckt"></td>
+    <td class="cht">Symplectique</td>
+    <td class="cht5">Mesotympanic</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Os symplecticum</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">32.</td>
+    <td class="brckt"></td>
+    <td class="cht">Sousopercule</td>
+    <td class="cht5"><i>Suboperculum</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Suboperculum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">33.</td>
+    <td class="brckt"></td>
+    <td class="cht">Interopercule</td>
+    <td class="cht5"><i>Interoperculum</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Interoperculum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">34.</td>
+    <td class="brckt"></td>
+    <td class="cht">Dentaire</td>
+    <td class="cht5"><i>Dentary</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os dentale</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">35.</td>
+    <td class="brckt"></td>
+    <td class="cht">Articulaire</td>
+    <td class="cht5"><i>Articulary</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os articulare</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">36.</td>
+    <td class="brckt"></td>
+    <td class="cht">Angulaire</td>
+    <td class="cht5"><i>Angular</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os angulare</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">37.</td>
+    <td class="brckt" rowspan="2"><img src="images/big_right_bracket.png"
+ alt="big right bracket"  style="height:4.5em; padding:0 1em 0 1em;"></td>
+    <td class="cht">Grandes pièces latérales</td>
+    <td class="cht5"><i>Epihyal</i></td>
+    <td class="brckt" rowspan="4"><img src="images/big_right_bracket.png"
+ alt="big right bracket"  style="height:8.5em; padding:0 1em 0 1em;"></td>
+    <td class="cht6">Segmente der Zungenbein-Schenkel</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">38.</td>
+    <td class="cht"></td>
+    <td class="cht5"><i>Ceratohyal</i></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">39.</td>
+    <td class="brckt" rowspan="2"><img src="images/big_right_bracket.png"
+ alt="big right bracket"  style="height:3.5em; padding:0 1em 0 1em;"></td>
+    <td class="cht">Petites pièces laterales</td>
+    <td class="cht5"><i>Basihyal</i></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">40.</td>
+    <td class="cht"></td>
+    <td class="cht5"></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">41.</td>
+    <td class="brckt"></td>
+    <td class="cht">Os lingual</td>
+    <td class="cht5"><i>Glossohyal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Os linguale s. entoglossum</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">42.</td>
+    <td class="brckt"></td>
+    <td class="cht">Queue de l’os hyoide</td>
+    <td class="cht5"><i>Urohyal</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht">Basibranchiostegal (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">43.</td>
+    <td class="brckt"></td>
+    <td class="cht">Rayon branchiostège</td>
+    <td class="cht5"><i>Branchiostegal</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Radii branchiostegi</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">46.</td>
+    <td class="brckt"></td>
+    <td class="cht">Surscapulaire</td>
+    <td class="cht5">Suprascapula</td>
+    <td class="brckt"></td>
+    <td class="cht">Omolita</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Post-temporal</i> (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">47.</td>
+    <td class="brckt"></td>
+    <td class="cht">Scapulaire</td>
+    <td class="cht5">Scapula</td>
+    <td class="brckt"></td>
+    <td class="cht">Scapula</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Supraclavicula</i> (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">48.</td>
+    <td class="brckt"></td>
+    <td class="cht">Humeral</td>
+    <td class="cht5">Coracoid</td>
+    <td class="brckt"></td>
+    <td class="cht">Clavicula</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Clavicula</i> (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">49.</td>
+    <td class="brckt" rowspan="2"><img src="images/big_right_bracket.png"
+ alt="big right bracket"  style="height:3.5em; padding:0 1em 0 1em;"></td>
+    <td class="cht6" rowspan="2">Coracoid</td>
+    <td class="cht7" rowspan="2">Epicoracoid</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht6" rowspan="2"><i>Postclavicula</i> (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">50.</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">51.</td>
+    <td class="brckt"></td>
+    <td class="cht">Cubital</td>
+    <td class="cht5">Radius</td>
+    <td class="brckt" rowspan="2"><img src="images/big_right_bracket.png"
+ alt="big right bracket"  style="height:2.5em; padding:0 1em 0 1em;"></td>
+    <td class="cht6" rowspan="2">Ossa carpi</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Coracoid</i> (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">52.</td>
+    <td class="brckt"></td>
+    <td class="cht">Radial</td>
+    <td class="cht5">Ulna</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Scapula</i> (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn1" rowspan="2">53.</td>
+    <td class="brckt" rowspan="2"></td>
+    <td class="cht6" rowspan="2">Os du carpe</td>
+    <td class="cht7" rowspan="2"><i>Carpals</i></td>
+    <td class="brckt" rowspan="2"></td>
+    <td class="cht6" rowspan="2"> Ossa metacarpi</td>
+    <td class="brckt" rowspan="2"><img src="images/big_left_bracket.png"
+ alt="big left bracket"  style="height:2.5em; padding:0 1em 0 1em;"></td>
+    <td class="cht"><i>Basalia</i> (Huxley),</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Brachials (Parker)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">53 bis.</td>
+    <td class="brckt" rowspan="3"><img src="images/big_right_bracket.png"
+ alt="big right bracket"  style="height:3.5em; padding:0 1em 0 1em;"></td>
+    <td class="cht6" rowspan="3">Chaine intermédiaire</td>
+    <td class="cht7" rowspan="3"><i>Basibranchials</i></td>
+    <td class="brckt"></td>
+    <td class="cht6" rowspan="3">Copula</td>
+    <td class="brckt"></td>
+    <td class="cht6"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">55.</td>
+    <td class="brckt"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">54.</td>
+    <td class="brckt"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">56.</td>
+    <td class="brckt"></td>
+    <td class="cht">Pharyngiens inférieurs</td>
+    <td class="cht5"><i>Lower Pharyngeals</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Ossa pharyngea inferiora</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">57.</td>
+    <td class="brckt"></td>
+    <td class="cht">Pièce interne de partie inférieure de l’arceau branchiale</td>
+    <td class="cht5"><i>Hypobranchial</i></td>
+    <td class="brckt" rowspan="4"><img src="images/big_right_bracket.png"
+ alt="big right bracket"  style="height:9em; padding:0 1em 0 1em;"></td>
+    <td class="cht6" rowspan="4">Segmente der Kiemenbogen-Schenkel</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">58.</td>
+    <td class="brckt"></td>
+    <td class="cht">Pièce externe „</td>
+    <td class="cht5"><i>Ceratobranchial</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">59.</td>
+    <td class="brckt"></td>
+    <td class="cht">Stylet de prémière arceau branchiale</td>
+    <td class="cht5"><i>Upper epibranchial of first branchial arch</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">61.</td>
+    <td class="brckt"></td>
+    <td class="cht">Partie supérieure de l’arceau branchiale</td>
+    <td class="cht5"><i>Epibranchials</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">62.</td>
+    <td class="brckt"></td>
+    <td class="cht">Os pharyngian supérieur</td>
+    <td class="cht5">Pharyngobranchial</td>
+    <td class="brckt"></td>
+    <td class="cht">Os pharyngeum superius</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Upper pharyngeals</i></td>
+  </tr>
+
+  <tr>
+    <td class="chn">63.</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="cht5"><i>Gill-rakers</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">65.</td>
+    <td class="brckt"></td>
+    <td class="cht">Rayons de la pectorale</td>
+    <td class="cht5"><i>Pectoral rays</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Brustflossen-Strablen</td>
+    <td class="brckt"></td>
+    <td class="cht"><span class="pagenum" id="Page_62">[62]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chn">67, 68.</td>
+    <td class="brckt"></td>
+    <td class="cht">Vertèbres abdominales</td>
+    <td class="cht5"><i>Abdominal vertebræ</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Bauchwirbel</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">69.</td>
+    <td class="brckt"></td>
+    <td class="cht">Vertèbres caudales</td>
+    <td class="cht5"><i>Caudal vertebræ</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Schwanzwirbel</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">70.</td>
+    <td class="brckt"></td>
+    <td class="cht">Plaque triangulaire et verticale</td>
+    <td class="cht5">[Aggregated interhæmals]</td>
+    <td class="brckt"></td>
+    <td class="cht">Verticale Platte</td>
+    <td class="brckt"></td>
+    <td class="cht"><i>Hypural</i> (Huxley)</td>
+  </tr>
+
+  <tr>
+    <td class="chn">71.</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="cht5"><i>Caudal rays</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Schwanzflossen Strahlen</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">72.</td>
+    <td class="brckt"></td>
+    <td class="cht">Côte</td>
+    <td class="cht5"><i>Rib</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Rippen</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">73.</td>
+    <td class="brckt"></td>
+    <td class="cht">Appendices or stylets</td>
+    <td class="cht5"><i>Epipleural spines</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Muskel-Gräthen</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">74.</td>
+    <td class="brckt"></td>
+    <td class="cht">Interépineux</td>
+    <td class="cht5"><i>Interneural spines</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Ossa interspinalia s. obere Flossentræger</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">75.</td>
+    <td class="brckt"></td>
+    <td class="cht">Épines et rayons dorsales</td>
+    <td class="cht5"><i>Dorsal rays and spines</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Rückenflossen-Strablen u. Stacheln</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">76.</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="cht5"><i>First interneural</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">78.</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="cht5"><i>Rudimentary caudal rays</i></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">79.</td>
+    <td class="brckt"></td>
+    <td class="cht">Apophyses épineuses inférieures</td>
+    <td class="cht5"><i>Interhæmal spines</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Untere Flossentræger</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">80.</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="cht5"><i>Pubic</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Becken</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+
+  <tr>
+    <td class="chn">81.</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+    <td class="cht5"><i>Ventral spine</i></td>
+    <td class="brckt"></td>
+    <td class="cht">Bauchflossen-Stachel</td>
+    <td class="brckt"></td>
+    <td class="cht"></td>
+  </tr>
+</table>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_63">[63]</span></p>
+
+<h2 class="smaller">CHAPTER IV.<br>
+<span class="subhed">MODIFICATIONS OF THE SKELETON.</span></h2></div>
+
+<p>The lowermost sub-class of fishes, which comprises one form
+only, the Lancelet (<i>Branchiostoma</i> [s. <i>Amphioxus</i>]
+<i>lanceolatum</i>), possesses the skeleton of the most primitive type.</p>
+
+  <div class="figcenter" id="fig28" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig28.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 28.—Branchiostoma lanceolatum. <i>a</i>, Mouth;
+<i>b</i>, Vent; <i>c</i>, abdominal porus.</p>
+  </div>
+
+  <div class="figcenter" id="fig29" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig29.jpg"
+     alt="">
+     <p class="p0 p-left hangingindent smaller">Fig. 29.—Anterior end of body of Branchiostoma
+(magn.) <i>d</i>, Chorda dorsalis; <i>e</i>, Spinal chord; <i>f</i>,
+Cartilaginous rods; <i>g</i>, Eye; <i>h</i>, Branchial rods; <i>i</i>,
+Labial cartilage; <i>k</i>, Oral cirrhi.</p>
+  </div>
+
+<p>The vertebral column is represented by a simple <i>chorda</i>
+<i>dorsalis</i> or <i>notochord</i> only, which extends from one
+extremity of the fish to the other, and, so far from being expanded
+into<span class="pagenum" id="Page_64">[64]</span> a cranial cavity, it is pointed at its anterior end as well as
+at its posterior. It is enveloped in a simple membrane like the spinal
+chord and the abdominal organs, and there is no trace of vertebral
+segments or ribs; however, a series of short cartilaginous rods
+above the spine evidently represent apophyses. A maxillary or hyoid
+apparatus, or elements representing limbs, are entirely absent.</p>
+
+<div class="blockquot">
+
+<p>[J. Müller, Ueber den Bau und die Lebenserscheinungen des
+<i>Branchiostoma lubricum</i>, in Abhandl. Ak. Wiss. Berlin,
+1844.]</p>
+</div>
+
+<p>The skeleton of the <i>Cyclostomata</i> (or Marsipobranchii) (Lampreys
+and Sea-hags) shows a considerable advance of development. It consists
+of a notochord, the anterior pointed end of which is wedged into the
+base of a cranial capsule, partly membranous partly cartilaginous. This
+skull, therefore, is not movable upon the spinal column. No vertebral
+segmentation can be observed in the notochord, but neural arches are
+represented by a series of cartilages on each side of the spinal chord.
+In <i>Petromyzon</i> (Fig. <a href="#fig30">30</a>) the basis cranii emits two prolongations
+on each side: an inferior, extending for some distance along the lower
+side of the spinal column, and a lateral, which is ramified into a
+skeleton supporting the branchial apparatus. A stylohyal process and a
+subocular arch with a palato-pterygoid portion may be distinguished.
+The roof of the cranial capsule is membranous in <i>Myxine</i> and in
+the larvæ of <i>Petromyzon</i>, but more or less cartilaginous in the
+adult <i>Petromyzon</i> and in <i>Bdellostoma</i>. A cartilaginous
+capsule on each side of the hinder part of the skull contains the
+auditory organ, whilst the olfactory capsule occupies the anterior
+upper part of the roof. A broad cartilaginous lamina, starting from
+the cranium and overlying part of the snout, has been determined as
+representing the ethmo-vomerine elements, whilst the oral organs
+are supported by large, very peculiar cartilages (<i>labials</i>),
+greatly differing in general configuration and arrangement in the
+various Cyclostomes. There<span class="pagenum" id="Page_65">[65]</span> are three in the Sea-lamprey, of which the
+middle one is joined to the palate by an intermediate smaller one; the
+foremost is ring-like, tooth-bearing, emitting on each side a styliform
+process. The lingual cartilage is large in all Cyclostomes.</p>
+
+<p><span class="pagenum" id="Page_66">[66]</span></p>
+
+<p>There is no trace of ribs or limbs.</p>
+
+<div class="blockquot">
+
+<p>[J. Müller, Vergleichende Anatomie der Myxinoiden. Erster Theil.
+Osteologie und Myologie, in Abhandl. Ak. Wiss. Berlin, 1835.]</p>
+</div>
+
+  <div class="figcenter" id="fig30" style="max-width: 583px">
+     <img
+    class="p1"   
+    src="images/fig30.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 30.—Upper (A) and side (B) views, and vertical
+section (C) of the skull of <i>Petromyzon marinus</i>.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Notochord; <i>b</i>, Basis cranii; <i>c</i>,
+Inferior, and <i>d</i>, Lateral process of basis; <i>e</i>,
+Auditory capsule; <i>f</i>, Subocular arch; <i>g</i>, Stylohyal
+process; <i>h</i>, Olfactory capsule; <i>i</i>, Ethmo-vomerine
+plate; <i>k</i>, Palato-pterygoid portion of subocular arch;
+<i>l-n</i>, Accessory labial or rostral cartilages; with
+<i>o</i>, appendage; <i>p</i>, lingual cartilage; <i>q</i>,
+neural arches; <i>r</i>, Branchial skeleton; <i>s</i>, Blind
+termination of the nasal duct between the notochord and
+œsophagus.</p>
+  </div>
+
+  <div class="figcenter" id="fig31" style="max-width: 511px">
+     <img
+    class="p1"   
+    src="images/fig31.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 31.—Heterocercal Tail of Centrina salviani.</p>
+     <p class="p0 center smaller"><i>a</i>, Vertebræ; <i>b</i>, Neurapophyses; <i>c</i>, Hæmapophyses.</p>
+  </div>
+
+<p>The <i>Chondropterygians</i> exhibit a most extraordinary diversity
+in the development of their vertebral column; almost every degree
+of ossification, from a notochord without a trace of annular
+structure to a series of completely ossified vertebræ being found
+in this order. Sharks, in which the notochord is persistent, are
+the <i>Holocephali</i> (if they be reckoned to this order, and the
+genera <i>Notidanus</i> and <i>Echinorhinus</i>). Among the first,
+<i>Chimæra monstrosa</i> begins to show traces of segmentation; but
+they are limited to the outer sheath of the notochord, in which slender
+subossified rings appear. In <i>Notidanus</i> membranous septa, with a
+central vacuity, cross the substance of the gelatinous notochord. In
+the other Sharks the segmentation is complete, each vertebra having
+a deep conical excavation in front and behind, with a central canal
+through which the notochord is continued; but the degree in which the
+primitive cartilage is replaced by concentric<span class="pagenum" id="Page_67">[67]</span> or radiating lamellæ of
+bone varies greatly in the various genera, and according to the age of
+the individuals. In the Rays all the vertebræ are completely ossified,
+and the anterior ones confluent into one continuous mass.</p>
+
+<p>In the majority of Chondropterygians the extremity of the vertebral
+column shows a decidedly heterocercal condition (Fig. <a href="#fig31">31</a>), and only a
+few, like <i>Squatina</i> and some Rays, possess a diphycercal tail</p>
+
+<p>The advance in the development of the skeleton of the Chondropterygians
+beyond the primitive condition of the previous sub-classes, manifests
+itself further by the presence of neural and hæmal elements, which
+extend to the foremost part of the axial column, but of which the hæmal
+form a closed arch in the caudal region only, whilst on the trunk they
+appear merely as a lateral longitudinal ridge.</p>
+
+  <div class="figcenter" id="fig32" style="max-width: 255px">
+     <img
+    class="p1"   
+    src="images/fig32.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 32.—Lateral view.</p>
+  </div>
+
+  <div class="figcenter" id="fig33" style="max-width: 328px">
+     <img
+    class="p1"   
+    src="images/fig33.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 33.—Longitudinal section.</p>
+  </div>
+
+  <div class="figcenter" id="fig34" style="max-width: 328px">
+     <img
+    class="p1"   
+    src="images/fig34.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 34.—Transverse section of Caudal vertebra of Basking Shark (Selache
+maxima). (After Hasse.) <i>a</i>, Centrum; <i>b</i>, Neurapophysis;
+<i>c</i>, Intercrural cartilage; <i>d</i>, Hæmapophysis; <i>e</i>,
+Spinal canal; <i>f</i>, Intervertebral cavity; <i>g</i>, Central
+canal for persistent portion of notochord; <i>h</i>, Hæmal canals for
+blood-vessels.</p>
+  </div>
+
+<p>The neural and hæmal apophyses are either merely attached to the
+axis, as in Chondropterygians with persistent notochord, the Rays
+and some Sharks; or their basal portions penetrate like wedges into
+the substance of the centrum, so that, in a transverse section,
+in consequence of<span class="pagenum" id="Page_68">[68]</span> the difference in their texture, they appear
+in the form of an X.<a id="FNanchor_6" href="#Footnote_6" class="fnanchor">[6]</a> The interspaces between the neurapophyses
+of the vertebræ are not filled by fibrous membrane, as in other
+fishes, but by separate cartilages, <i>laminæ</i> or <i>cartilagines
+intercrurales</i>, to which frequently a series of terminal pieces
+is superadded, which must be regarded as the first appearance of the
+interneural spines of the Teleostei and many Ganoids. Similar terminal
+pieces are sometimes observed on the hæmal arches. <i>Ribs</i> are
+either absent or but imperfectly represented (<i>Carcharias</i>).</p>
+
+<p>The substance of the <i>skull</i> of the Chondropterygians is
+cartilage, interrupted especially on its upper surface by more or less
+extensive fibro-membranous fontanelles. Superficially it is covered by
+a more or less thick chagreen-like osseous deposit. The articulation
+with the vertebral column is effected by a pair of lateral condyles. In
+the Sharks, besides, a central conical excavation corresponds to that
+of the centrum of the foremost vertebral segment, whilst in the Rays
+this central excavation of the skull receives a condyle of the axis of
+the spinous column.</p>
+
+<p>The cranium itself is a continuous undivided cartilage, in which the
+limits of the orbit are well marked by an anterior and posterior
+protuberance. The ethmoidal region sends horizontal plates over
+the nasal sacs, the apertures of which retain their embryonic
+situation upon the under surface of the skull. In the majority of
+Chondropterygians these plates are conically produced, forming the base
+of the soft projecting snout; and in some forms, especially in the
+long-snouted Rays and the Saw-fishes (<i>Pristis</i>) this prolongation
+appears in the form of three or more tubiform rods.</p>
+
+<p><span class="pagenum" id="Page_69">[69]</span></p>
+
+<p>As separate cartilages there are appended to the skull a suspensorium,
+a palatine, mandible, hyoid, and rudimentary maxillary elements.</p>
+
+<p>The suspensorium is movably attached to the side of the skull. It
+generally consists of one piece only, but in some Rays of two. In the
+Rays it is articulated with the mandible only, their hyoid possessing
+a distinct point of attachment to the skull. In the Sharks the hyoid
+is suspended from the lower end of the suspensorium together with the
+mandible.</p>
+
+<p>What is generally called the upper jaw of a Shark is, as Cuvier has
+already stated, not the maxillary, but palatine. It consists of two
+simple lateral halves, each of which articulates with the corresponding
+half of the lower jaw, which is formed by the simple representative of
+Meckel’s cartilage.</p>
+
+<p>Some cartilages of various sizes are generally developed on each side
+of the palatine, and one on each side of the mandible. They are called
+<i>labial</i> cartilages, and seem to represent maxillary elements.</p>
+
+<p>The <i>hyoid</i> consists generally of a pair of long and strong
+lateral pieces, and a single mesial piece. From the former
+cartilaginous filaments (representing branchiostegals) pass directly
+outwards. Branchial arches, varying in number, and similar to the
+hyoid, succeed it. They are suspended from the side of the foremost
+part of the spinous column, and, like the hyoid, bear a number of
+filaments.</p>
+
+<p>The vertical fins are supported by interneural and interhæmal
+cartilages, each of which consists of two and more pieces, and to which
+the fin-rays are attached without articulation.</p>
+
+<p>The <i>scapular arch</i> of the Sharks is formed by a single coracoid
+cartilage bent from the dorsal region downwards and forwards. In
+some genera (<i>Scyllium</i>, <i>Squatina</i>) a small separate
+scapular cartilage is attached to the dorsal extremities of the
+coracoid; but in none of the Elasmobranchs is the<span class="pagenum" id="Page_70">[70]</span> scapular arch
+suspended from the skull or vertebral column; it is merely sunk,
+and fixed in the substance of the muscles. Behind, at the point of
+its greatest curvature, three carpal cartilages are joined to the
+coracoid, which Gegenbaur has distinguished as <i>propterygium</i>,
+<i>mesopterygium</i>, and <i>metapterygium</i>, the former occupying
+the front, the latter the hind margin of the fin. Several more or
+less regular transverse series of styliform cartilages follow. They
+represent the phalanges, to which the horny filaments which are
+imbedded in the skin of the fin are attached.</p>
+
+<p>In the Rays, with the exception of <i>Torpedo</i>, the scapular arch
+is intimately connected with the confluent anterior portion of the
+vertebral column. The anterior and posterior carpal cartilages are
+followed by a series of similar pieces, which extend like an arch
+forwards to the rostral portion of the skull, and backwards to the
+pubic region. Extremely numerous phalangeal elements, longest in the
+middle, are supported by the carpals, and form the skeleton of the
+lateral expansion of the so-called <i>disk</i> of the Ray’s body, which
+thus, in fact, is nothing but the enormously enlarged pectoral fin.</p>
+
+<p>The <i>pubic</i> is represented by a single median transverse
+cartilage, with which a tarsal cartilage articulates. The latter
+supports the fin-rays. To the end of this cartilage is also attached,
+in the male Chondropterygians, a peculiar accessory generative organ or
+clasper.</p>
+
+<p>The <i>Holocephali</i> differ from the other Chondropterygians in
+several important points of the structure of their skeleton, and
+approach unmistakably certain Ganoids. That their spinal column is
+persistently notochordal has been mentioned already. Their palatal
+apparatus, with the suspensorium, coalesces with the skull, the
+mandible articulating with a short apophysis of the cranial cartilage.
+The mandible is simple, without anterior symphysis. The spine with
+which<span class="pagenum" id="Page_71">[71]</span> the dorsal fin is armed articulates with a neural apophysis, and
+is not immovably attached to it, as in the Sharks. The pubic consists
+of two lateral halves, with a short, rounded, tarsal cartilage.</p>
+
+<p>The skeleton of the <i>Ganoid</i> Fishes offers extreme variations with
+regard to the degree in which ossifications replace the primordial
+cartilage. Whilst some exhibit scarcely any advance beyond the
+Plagiostomes with persistent cartilage, others approach, as regards the
+development and specialisation of the several parts of their osseous
+framework, the Teleosteans so closely that their Ganoid nature can
+be demonstrated by, or inferred from, other considerations only. All
+Ganoids possess a separate gill-cover.<a id="FNanchor_7" href="#Footnote_7" class="fnanchor">[7]</a></p>
+
+<p>The diversity in the development of the Ganoid skeleton is well
+exemplified by the few representatives of the order in the existing
+Fish-fauna. Lowest in the scale (in this respect) are those with a
+persistent notochord, and an <i>autostylic</i> skull, that is, a
+skull without separate suspensorium—the fishes constituting the
+suborder <i>Dipnoi</i>, of which the existing representatives are
+<i>Lepidosiren</i>, <i>Protopterus</i>, and <i>Ceratodus</i>, and
+the extinct (as far as demonstrated at present) <i>Dipterus</i>,
+<i>Chirodus</i> (and <i>Phaneropleuron</i>?). In these fishes the
+notochord is persistent, passing uninterruptedly into the cartilaginous
+base of the skull. Only now and then a distinct vertical segmentation
+occurs in the caudal portion of the column, but it does not extend
+to the notochord itself, but indicates only the limits between the
+superadded apophyseal elements, each neural being confluent with the
+opposite hæmal. Some <i>Dipnoi</i> are diphy-, others heterocercal.</p>
+
+<p><span class="pagenum" id="Page_72">[72]</span></p>
+
+<p>Neural and hæmal elements and ribs are well developed. In
+<i>Ceratodus</i> each neurapophysis consists of a basal cartilaginous
+portion, forming an arch over the myelon, and of a superadded second
+portion. The latter is separated from the former by a distinct line of
+demarcation, and its two branches are more styliform, cartilaginous
+at the ends and in the centre, but with an osseous sheath, and
+coalesced at the top, forming a gable over an elastic fibrous band
+which runs along and parallel to the longitudinal axis of the column
+(<i>Ligamentum longitudinale superius</i>). To the top of this gable
+is joined a single long cylindrical neural spine. From the eleventh
+apophyseal segment a distinct interneural spine, of the same structure
+as the neural, begins to be developed, and farther on a second
+interneural is superadded. Towards the extremity of the column these
+various pieces are gradually reduced in size and number, finally
+only a low cartilaginous band (the rudiments of the neurapophysis)
+remaining. The <i>hæmapophyses</i> are in form, size, and structure,
+very similar to the neurapophyses; and all these long bones, including
+the ribs, have that in common, that they consist of a solid rod of
+cartilage enclosed in a bony sheath, which, after the disappearance or
+decomposition of the cartilage, appears as a hollow tube. Such bones
+are extremely common throughout the order of Ganoids, and their remains
+have led to the designation of a family as <i>Cœlacanthi</i> (κοιλος,
+hollow; and ἀκανθος, spine).</p>
+
+<p>The primordial <i>cranium</i> of the <i>Dipnoi</i> is cartilaginous,
+but with more or less extensive ossifications in its occipital,
+basal, or lateral portions, and with large tegumentary bones, the
+arrangement of which varies in the different genera. There is no
+separate suspensorium for the lower jaw. A strong process descends from
+the cranial cartilage, and offers by means of a double condyle (Fig.
+<a href="#fig35">35</a> <i>s</i>) attachment to corresponding articulary surfaces of the
+lower jaw.<span class="pagenum" id="Page_73">[73]</span> Maxillary and intermaxillary elements are not developed,
+but, perhaps, represented in <i>Ceratodus</i> by some inconstant
+rudimentary labial cartilages situated behind the posterior nasal
+opening. Facial cartilages and an infraorbital ring are developed
+at least in <i>Ceratodus</i>. The presence of a pair of small teeth
+in front indicates the vomerine portion (<i>v</i>) which remains
+cartilage, whilst the posterior pair of teeth are implanted in a
+pterygo-palatine ossification (<i>l</i>), which sometimes is paired,
+sometimes continuous. The base of the skull is constantly covered by a
+large basal ossification (<i>o</i>).</p>
+
+  <div class="figcenter" id="fig35" style="max-width: 483px">
+     <img
+    class="p1"   
+    src="images/fig35.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 35.—Palatal view of Skull of Ceratodus.</p>
+  </div>
+
+<p>The <i>hyoid</i> is well developed, sometimes reduced to a pair of
+ceratohyals, sometimes with a basihyal and glossyhyal. The skeleton of
+the <i>branchial apparatus</i> approaches the Teleosteous type, less so
+in <i>Lepidosiren</i> than in <i>Ceratodus</i>, in which five branchial
+arches are developed, but with the lateral and mesial pieces reduced in
+number.</p>
+
+<p>A large operculum, and a smaller sub- or interoperculum are present.</p>
+
+<p>The <i>scapular</i> arch consists of a single median transverse
+cartilage, and a pair of lateral cartilages which bear the articular
+condyle for the pectoral limb. The latter cartilages form the base of a
+large membrane-bone, and the whole arch is suspended from the skull by
+means of an osseous supraclavicle.</p>
+
+<p>The fore-limb of the <i>Dipnoi</i> (Fig. <a href="#fig36">36</a>) differs externally greatly
+from the pectoral fin of other Ganoid fishes. It is covered with
+small scales along the middle, from the root<span class="pagenum" id="Page_74">[74]</span> to its extremity, and
+surrounded by a rayed fringe similar to the vertical fin. A muscle
+split into numerous fascicles extends all the length of the fin, which
+is flexible in every part and in every direction. The cartilaginous
+framework supporting it is joined to the scapular arch by an oblong
+cartilage, followed by a broad basal cartilage (<i>a</i>), generally
+single, sometimes showing traces of a triple division. Along the
+middle of the fin runs a jointed axis (<i>b</i>), the joints gradually
+becoming smaller and thinner towards the extremity; each joint bears
+on each side a three, two, or one-jointed branch (<i>c, d</i>). This
+<i>axial</i> arrangement of the pectoral skeleton, which evidently
+represents one of its first and lowest conditions, has been termed
+<i>Archipterygium</i> by Gegenbaur. It is found in <i>Ceratodus</i> and
+other genera, but in <i>Lepidosiren</i> the jointed axis only has been
+preserved, with the addition of rudimentary rays in <i>Protopterus</i>.</p>
+
+  <div class="figcenter" id="fig36" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig36.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 36.—Fore-limb of Ceratodus.</p>
+  </div>
+
+<p>The <i>pubic</i> consists of a single flattened subquadrangular
+cartilage, produced into a long single anterior process. Posteriorly it
+terminates on each side in a condyle, to which the basal cartilage of
+the ventral paddle is joined. The endoskeleton of the paddle is almost
+identical with that of the pectoral.</p>
+
+<p>The Ganoid fishes with persistent notochord, but with a
+<i>hyostylic</i> skull (that is, a skull with a separate
+suspensorium) consist of the suborder <i>Chondrostei</i>, of which
+the existing representatives are the Sturgeons (<i>Acipenser</i>,
+<i>Scaphirhynchus</i>,<span class="pagenum" id="Page_75">[75]</span> <i>Polyodon</i>), and the extinct the
+<i>Chondrosteidæ</i>, <i>Palæoniscidæ</i>, and (according to Traquair)
+<i>Platysomidæ</i>.</p>
+
+<p>Their spinal column does not differ essentially from that of the
+Dipnoi. Segmentation is represented only as far as the neural and
+hæmal elements are concerned. All are eminently heterocercal. Ribs are
+present in most, but replaced by ligaments in <i>Polyodon</i>.</p>
+
+  <div class="figcenter" id="fig37" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig37.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 37.—Skull of Polyodon (after Traquair).</p>
+     <p class="p0 p-left hangingindent smaller"><i>n</i>, Nasal cavity; <i>sq</i>, squamosal; <i>mh</i>,
+hyomandibular; <i>sy</i>, symplectic; <i>pa</i>,
+palato-pterygoid; <i>m</i>, Meckelian cartilage; <i>mx</i>,
+maxillary; <i>d</i>, dentary; <i>h</i>, hyoid; <i>op</i>,
+opercle; <i>br</i>, branchiostegal; <i>s.cl</i>,
+supra-clavicular; <i>p.cl</i>, post-clavicular; <i>cl</i>,
+clavicle; <i>i.cl</i>, infra-clavicular.</p>
+  </div>
+
+<p>The primordial cranium of the Sturgeons consists of persistent
+cartilage without ossifications in its substance, but superficial bones
+are still more developed and specialised than in the Dipnoi; so it
+is, at least, in the true Sturgeons, but less so in <i>Polyodon</i>
+(Fig. <a href="#fig37">37</a>). The upper and lateral parts of the skull are covered by
+well-developed <i>membrane bones</i>, which, from this suborder,
+upwards in the series, will be found to exist throughout the remaining
+forms of fishes. They are bones, the origin of which is not in
+cartilage but in membranous connective tissue. The lower surface of
+the skull is covered by an extremely large basal bone, which extends
+from the vomerine region on to the anterior part of the spinal column.
+The nasal excavation in the skull is rather lateral than inferior. The
+ethmoidal region is generally much produced, forming<span class="pagenum" id="Page_76">[76]</span> the base of the
+long projecting snout. The suspensorium is movably attached to the
+side of the skull, and consists of two pieces, a hyomandibular and a
+symplectic, which now appears for the first time as a separate piece,
+and to which the hyoid is attached. The palato-maxillary apparatus is
+more complex than in the Sharks and Dipnoi; a palato-pterygoid consists
+of two mesially-connected rami in <i>Polyodon</i>, and of a complex
+cartilaginous disk in <i>Acipenser</i>, being articulated in both to
+the Meckelian cartilage. In addition, the Sturgeons possess one or two
+pairs of osseous rods, which, in <i>Polyodon</i> at least, represent
+the maxillary, and therefore must be the representatives of the labial
+cartilages of the Sharks. The Meckelian cartilage is more or less
+covered by tegumentary bones.</p>
+
+<p>In the gill-cover, besides the operculum, a sub- and interoperculum may
+be distinguished in <i>Acipenser.</i></p>
+
+<p>The hyoid consists of three pieces, of which the posterior bears a
+broad branchiostegal in <i>Polyodon.</i></p>
+
+<p>In the scapulary arch the primordial cartilaginous elements scarcely
+differ from those of the <i>Dipnoi.</i> The membrane-bones are much
+expanded, and offer a continuous series suspended from the skull. Their
+division in the median ventral line is complete.</p>
+
+  <div class="figcenter" id="fig38" style="max-width: 207px">
+     <img
+    class="p1"   
+    src="images/fig38.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 38.—Fore-limb of Acipenser.</p>
+  </div>
+
+<p>The pectoral is supported by a cartilaginous framework (Fig. <a href="#fig38">38</a>)
+similar to that of <i>Ceratodus</i>, but much more shortened and
+reduced in its periphery, the branches being absent altogether on one
+side of the axis. This modification of the fin is analogous to the
+heterocercal condition of the end of the spinous column. To the inner<span class="pagenum" id="Page_77">[77]</span>
+corner of a basal cartilage (<i>a</i>) a short axis (<i>b</i>) is
+joined, which on its outer side bears a few branches (<i>d</i>) only,
+the remaining branches (<i>c</i>) being fixed to the basal cartilage.
+The dermal fin-rays are opposed to the extremities of the branches, as
+in the <i>Dipnoi</i>.</p>
+
+<p>The <i>pubic</i> consists of a paired cartilage, to which tarsal pieces
+supporting the fin-rays are attached.</p>
+
+<p>The other living Ganoid fishes have the spinous column entirely or
+nearly entirely ossified, and have been comprised under the common name
+<i>Holostei</i>. However, they form three very distinct types; several
+attempts have been made to coordinate with them the fossil forms, but
+this task is beset with extreme difficulties, and its solution hitherto
+has not proved to be satisfactory.</p>
+
+<p>The <i>Polypteroidei</i> have their spinous column formed by distinct
+osseous <i>amphicœlous</i> vertebræ, that is, vertebræ with concave
+anterior and posterior surfaces. It is nearly diphycercal; a slight
+degree of heterocercy obtains, inasmuch as the last vertebra is
+succeeded by a very thin cartilaginous filament which penetrates
+between the halves of one of the middle rays of the terminal fin.
+The rays above this cartilaginous filament are articulated to
+interneurals, those below lack interhæmals, and are attached either to
+the hæmals or vertebral centres. The neural arches, though ossified,
+do not coalesce with the centrum, and form one canal only, for the
+myelon. There are no intermediate elements between the neural spines.
+Interneurals developed, but simple, articulating with the dermoneurals.
+The abdominal vertebræ have parapophyses developed with epipleural
+spines. Only the caudal vertebræ have hæmal spines, which, like the
+interhæmals, agree in every essential respect with the opposite
+neurals. <i>Ribs</i> are inserted, not on the parapophyses, but on the
+centre, immediately below the parapophyses.</p>
+
+<p>The <i>skull</i> of <i>Polypterus</i> (Fig. <a href="#fig39">39</a>) shows a great advance<span class="pagenum" id="Page_78">[78]</span>
+towards the Teleosteous type, the number of separable bones<span class="pagenum" id="Page_79">[79]</span> being
+greatly increased. They are arranged much in the same fashion as in
+Teleostei. But a great portion of the primordial cranium remains
+cartilaginous. The membrane-bones which cover the upper and lower
+surfaces of the brain-case are so much developed as to cause the
+underlying cartilage to disappear, so that a large vacuity or
+fontanelle exists in the substance of the upper as well as lower
+cartilaginous wall. Of ossifications belonging to the primordial skull
+must be noticed the single occipital with a mastoid on each side.
+They are separated by persistent cartilage from the sphenoids and
+postfrontals; the former, which are the largest ossification of the
+primordial cranium, enclose the anterior half of the brain cavity.
+Finally, the nasal portion contains a median ethmoid and a pair of
+præfrontal bones.</p>
+
+  <div class="figcenter" id="fig39" style="max-width: 379px">
+     <img
+    class="p1"   
+    src="images/fig39.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 39.—Skull of Polypterus. (After Traquair.)</p>
+     <p class="p0 p-left hangingindent smaller">Fig. I. Upper aspect of the Primordial Cranium, with the
+membrane-bones removed. Fig. II. Lower aspect of the same. Fig.
+III. Side view, with the membrane-bones. Fig. IV. Lower aspect
+of the Skull, part of the bones being removed on one side. The
+parts shaded with oblique lines are cartilage of the primordial
+skull.</p>
+     <p class="p0 p-left hangingindent smaller"><i>An</i>, Angular; <i>ao</i>, ante-orbital; <i>Ar</i>,
+articulary; <i>B</i>, basal; <i>D</i>, dentary; <i>E</i>,
+ethmoid; <i>F</i>, frontal; <i>Ma</i>, mastoid; <i>Mp</i>,
+metapterygoid; <i>Mx</i>, maxillary; <i>N</i>, nasal; <i>O</i>,
+operculum; <i>Oc</i>, occipital; <i>Pa</i>, parietal; <i>Pl</i>,
+palatine; <i>Pmx</i>, præmaxillary; <i>po</i>, post-orbital;
+<i>Prf</i>, prefrontal; <i>Pt</i>, post-temporals; <i>Ptf</i>,
+postfrontal; <i>Ptr</i>, pterygoid; <i>Q</i>, quadrate;
+<i>S</i>, suspensorium; <i>So</i>, sub-operculum; <i>Sp</i>,
+sphenoid; <i>Spl</i>, splenial; <i>St</i>, supratemporals;
+<i>T</i>, tympanic lamina; <i>Tu</i>, turbinal; <i>v</i>, vomer;
+<i>x x</i>, small ossicles; <i>x’ x’</i>, spiraculars.</p>
+  </div>
+
+<p>Only a very small portion of the bones described are visible
+externally, nearly the whole of the primordial cranium being covered
+by the membrane-bones. Of these are seen on the upper surface a pair
+of parietals, frontals, “nasals,” and turbinals; on the lower surface
+a large cross-shaped basal, anteriorly bordered on each side by a
+pterygoid, parallel to a palatine which forms a suture with the double
+vomer. The suspensorium has in front a metapterygoid and quadrate bone,
+and an operculum and sub-operculum are attached to it behind.</p>
+
+<p>Præmaxillaries and maxillaries are now fully developed, but immovably
+attached to the skull. The lower jaw is ossified, and consists of an
+articulary, angular, dentary, and splenial. Of labial cartilages a
+rudiment at the angle of the mouth has remained persistent.</p>
+
+<p><span class="pagenum" id="Page_80">[80]</span></p>
+
+<p>The side of the skull, in front of the operculum, is covered by a large
+irregularly-shaped bone (<i>T</i>) (corresponding to the “tympanic
+lamina” of <i>Ceratodus</i>, Fig. <a href="#fig35">35</a>, <i>q</i>), held by some to be
+the præoperculum; along its upper circumference lies a series of small
+ossicles, of which two may be distinguished as spiraculars, as they
+form a valve for the protection of the spiracular orifice of these
+fishes. An infraorbital ring is represented by a præ- and post-orbital
+only.</p>
+
+<p>Each <i>hyoid</i> consists of three pieces, none of which bear
+branchiostegals, the single median piece being osseous in front and
+cartilaginous behind. Four branchial arches are developed, the foremost
+consisting of three, the second and third of two, and the last of a
+single piece. There is no lower pharyngeal. Between the rami of the
+lower jaw the throat is protected by a pair of large osseous laminæ
+(<i>gular plates</i>), which have been considered to represent the
+urohyal of osseous fishes.</p>
+
+<p>The scapulary arch is almost entirely formed by the well-developed
+membrane-bones, which in the ventral line are suturally united.
+The pectoral fin is supported by three bones, pro-, meso-, and
+metapterygium, of which the dilated middle one alone bears rays, and is
+excluded from the articulation with the shoulder-girdle.</p>
+
+<p>The pubic consists of paired bone, to which tarsal bones supporting the
+fin-rays are attached.</p>
+
+<p>In the <i>Lepidosteoidei</i> the vertebræ are completely ossified,
+and <i>opisthocœlous</i>, having a convexity in front and a concavity
+behind, as in some Amphibians. Though the end of the body externally
+appears nearly diphycercal, the termination of the vertebral column
+is, in fact, distinctly heterocercal (Fig. <a href="#fig40">40</a>). Its extremity remains
+cartilaginous, is turned upwards, and lies immediately below the scutes
+which cover the upper margin of the caudal fin. It is preceded by a
+few rudimentary vertebræ which gradually pass into the fully developed
+normal vertebræ. The caudal fin is suspended from hæmapophyses<span class="pagenum" id="Page_81">[81]</span> only,
+and does not extend to the neural side of the vertebral column. The
+neural arches coalesce with the centrum; interneurals simple. The
+abdominal vertebræ have parapophyses, to which the ribs are attached.
+Only the caudal vertebræ have hæmal spines.</p>
+
+  <div class="figcenter" id="fig40" style="max-width: 520px">
+     <img
+    class="p1"   
+    src="images/fig40.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 40.—Heterocercal Tail of Lepidosteus.</p>
+     <p class="p0 p-left hangingindent smaller"><i>n</i>, Vertebral column; <i>h</i>, hæmal spines; <i>dn</i>, fulcra;
+<i>dh</i>, lower fulcra.</p>
+  </div>
+
+<p>In the skull of <i>Lepidosteus</i> the cartilage of the endocranium is
+still more replaced by ossifications than in <i>Polypterus</i>; those
+ossifications, moreover, being represented by a greater number of
+discrete bones; especially the membrane-bones are greatly multiplied:
+the occipital, for instance, consists of three pieces; the vomer is
+double as in <i>Polypterus</i>; the maxillary consists of a series of
+pieces firmly united by suture. The symplectic reaches the lower jaw,
+so that the articulary is provided with a double joint, viz. for the
+symplectic and quadrate; the component parts of the lower jaw are as
+numerous as in reptiles, a dentary, splenial, articulary, angular,
+supra-angular, and coronary being distinct. The sides of the head
+are covered with numerous bones, and a præoperculum is developed in
+front of the gill-cover which, again, consists of an operculum and
+sub-operculum.</p>
+
+<p>Each hyoid consists of three pieces, of which the middle is the
+longest, the upper bearing the largest of the three<span class="pagenum" id="Page_82">[82]</span> branchiostegals
+which <i>Lepidosteus</i> possesses; a long and large glossohyal is
+intercalated between the lower ends of the hyoids. There are five
+branchial arches, the hindmost of which is modified into a lower
+pharyngeal; upper pharyngeals are likewise present as in the majority
+of Teleosteous fishes. No gular plate.</p>
+
+<p>Of the scapulary arch the two halves are separated by a suture in the
+median line; the membrane-bones are well developed, only a remnant of
+the primordial cartilage remaining; the supraclavicle is very similar
+to that of Teleosteous fishes, less so the post-temporal. The base to
+which the limb is attached is a single osseous plate, supporting on its
+posterior margin semi-ossified rods in small number, which bear the
+pectoral rays.</p>
+
+<p>The pubic consists of paired bone, the anterior ends of which overlap
+each other, the extremity of the right pubis being dorsad to that of
+the left. The elements representing a tarsus are quite rudimentary and
+reduced in number (two or three).</p>
+
+<p>The vertebral column of the <i>Amioidei</i> shows unmistakable
+characters of the Palæichthyic type. The arrangement of its component
+parts is extremely simple. The centra of the amphicœlous vertebræ are
+well ossified, but the neural and hæmal arches do not coalesce with the
+centra, from which they are separated by a thin layer of cartilage.
+Singularly, not every vertebra has apophyses: in the caudal portion of
+<i>Amia</i> the vertebræ are alternately provided with them and lack
+them. The heterocercal condition of the spinous column is well marked:
+as in the other Holostei the hindmost vertebræ are turned upwards,
+become smaller and smaller in size, and lose their neural arches, the
+hæmals remaining developed to the end. Finally, the column terminates
+in a thin cartilaginous band, which is received between the lateral
+halves of the fifth or sixth upper caudal ray. Interneurals<span class="pagenum" id="Page_83">[83]</span> and
+interhæmals simple. Only the abdominal vertebræ have parapophyses, with
+which the ribs are articulated.</p>
+
+<p>The configuration of the skull, and the development and arrangement
+of its component parts, approaches so much the Teleosteous type
+that, perhaps, there are greater differences in skulls of truly
+Teleosteous fishes than between the skulls of <i>Amia</i> and many
+<i>Physostomi</i>. Externally the cranium is entirely ossified; and
+the remains of the cartilaginous primordial cranium (which, however,
+has no vacuity in its roof) can only be seen in a section, and are
+of much less extent than in many Physostomous fishes. The immovable
+intermaxillary, the double vomer, the plurality of ossifications
+representing the articulary, the double articulary cavity of the
+mandible for junction with the quadrate and symplectic bones, remind
+us still of similar conditions in the skull of <i>Lepidosteus</i>, but
+the mobility and formation of the maxillary, the arrangement of the
+gill-covers, the development of the opercles, the suspensorium, the
+palate, the insertion of a number of branchiostegals on the long middle
+hyoid piece, the composition of the branchial framework (with upper
+and lower pharyngeals), are as in the Teleosteous type. A gular plate
+replaces the urohyal.</p>
+
+<p>The scapular arch is composed entirely of the membrane-bones found in
+the <i>Teleostei</i>, and the two sides are loosely united by ligament.
+The base to which the limb is attached is cartilaginous; short
+semi-ossified rods are arranged along its hinder margin and bear the
+pectoral rays.</p>
+
+<p>The skeleton of the hind-limb agrees entirely with that of
+<i>Lepidosteus</i>.</p>
+
+<div class="blockquot">
+
+<p>[T. W. Bridge, The Cranial Osteology of <i>Amia calva</i>; in
+Journ. Anat. and Physiol. vol. xi.]</p>
+</div>
+
+<p>In the <i>Teleosteous</i> fishes the spinous column consists of
+completely ossified amphicœlous vertebræ; its termination is
+<i>homocercal</i>—that is, the caudal fin appears to be more or<span class="pagenum" id="Page_84">[84]</span> less
+symmetrical, the last vertebra occupying a central position in the
+base of the fin, and being coalesced with a flat osseous lamella, the
+<i>hypural</i> (Fig. <a href="#fig23">23</a>, <a href="#fig70">70</a>), on the hind margin of which the fin-rays
+are fixed. The hypural is but a union of modified hæmapophyses which
+are directed backwards, and the actual termination of the notochord
+is bent upwards, and lies along the upper edge of the hypural, hidden
+below the last rudimentary neural elements. In some Teleosteans, as the
+<i>Salmonidæ</i>, the last vertebræ are conspicuously bent upwards: in
+fact, strictly speaking, this homocercal condition is but one of the
+various degrees of heterocercy, different from that of many Ganoids
+in this respect only, that the caudal fin itself has assumed a higher
+degree of symmetry.</p>
+
+<p>The neural and hæmal arches generally coalesce with the centrum, but
+there are many exceptions, inasmuch as some portion of the arches of a
+species, or all of them, show the original division.</p>
+
+<p>The vertebræ are generally united with one another by zygapophyses, and
+frequently similar additional articulations exist at the lower parts
+of the centra. Parapophyses and ribs are very general, but the latter
+are inserted on the centra and the base of the processes, and never on
+their extremities. The point of insertion of the rib, more especially
+on the anterior vertebræ, may be still higher—viz. at the base of the
+neural arch, as in <i>Cotylis</i> and allied genera, and even on the
+top of the neurapophysis, as in <i>Batrachus</i>.</p>
+
+<p>There is a great amount of variation as regards the degree in which
+the primordial cranium persists; it is always more or less replaced
+by bone; frequently it disappears entirely, but in some fishes, like
+the <i>Salmonidæ</i> or <i>Esocidæ</i>, the cartilage persists to
+the same or even to a greater extent than in the Ganoidei holostei.
+Added to the bones preformed in cartilage are a great number of
+<i>membrane-bones</i>. The different kinds of these membrane-bones
+occur with greater or less<span class="pagenum" id="Page_85">[85]</span> constancy throughout this sub-class;
+they often coalesce with, and are no more separable from, the
+neighbouring or underlying cartilage-bones. All these bones have been
+topographically enumerated in Chapter IV.</p>
+
+<p>Many attempts have been made to classify the bones of the Teleosteous
+skull, according to their supposed relation to each other, or with
+the view to demonstrate the unity of plan on which the skull has been
+built; but in all either the one or the other of the following two
+principles has been followed:—</p>
+
+<p>A. The “vertebral doctrine” starts from the undeniable fact that the
+skull is originally composed of several segments, each of which is
+merely the modification of a vertebra. The component parts of such a
+cranial segment are considered to be homologous to those of a vertebra.
+Three, four, or five cranial vertebræ have been distinguished, all
+the various bones of the fully-developed and ossified skull being
+referred, without distinction as to their origin, to one or the other
+of those vertebral segments. The idea of the typical unity of the
+osseous framework of Vertebrates has been worked out with the greatest
+originality and knowledge of detail, by <i>Owen</i>, who demonstrates
+that the fish-skull is composed of <i>four</i> vertebræ.</p>
+
+<p>The bones of the fish-skull are, according to him, primarily divisible
+into those of the <i>neuroskeleton</i>, <i>splanchnoskeleton</i>, and
+<i>dermoskeleton</i>.</p>
+
+<p>The bones of the <i>neuro</i>- or proper <i>endoskeleton</i> are
+arranged in a series of four horizontally succeeding segments: the
+occipital, parietal, frontal, and nasal vertebræ; each segment
+consisting of an upper (neural) and a lower (hæmal) arch, with a common
+centre, and with diverging appendages.</p>
+
+<p>The <i>neural</i> arches of the four vertebræ, in their succession from
+the occiput towards the snout, are:—</p>
+
+<p>1. <i>Epencephalic arch</i>, composed of the occipitals.</p>
+
+<p><span class="pagenum" id="Page_86">[86]</span></p>
+
+<p>2. <i>Mesencephalic arch</i>, composed of basisphenoid, alisphenoid,
+parietal, and mastoid.</p>
+
+<p>3. <i>Prosencephalic arch</i>, composed of presphenoid,
+orbito-sphenoid, frontal, and postfrontal.</p>
+
+<p>4. <i>Rhinencephalic arch</i>, composed of vomer, prefrontal, and nasal.</p>
+
+<p>The <i>hæmal</i> arches in the same order of succession are:—</p>
+
+<p>1. <i>Scapular</i> or <i>scapulo-coracoid</i> arch, composed of
+suprascapula, scapula, and coracoid; its appendage consists of the
+ulna, radius and carpal.</p>
+
+<p>2. <i>Hyoid</i> or <i>stylo-hyoid</i> arch, composed of stylohyal,
+epihyal, ceratohyal, basihyal, glossohyal, and urohyal; its appendage
+is the branchiostegals.</p>
+
+<p>3. <i>Mandibular</i> or <i>tympano-mandibular</i> arch, composed of
+epi-, meso-, pre-, and hypo-tympanic, and the bones of the lower jaw;
+its appendage consists of the præoperculum and the other opercles.</p>
+
+<p>4. <i>Maxillary</i> or <i>palato-maxillary</i> arch, composed of
+palatine, maxillary, and premaxillary; its appendage consists of the
+pterygoid and entopterygoid.</p>
+
+<p>Parts of the <i>splanchnoskeleton</i> are held to be the ear-capsule
+or petrosal and the otolite, the eye-capsule or sclerotic, the
+nose-capsule or “ethmoid” and turbinal; the branchial arches.</p>
+
+<p>The bones of the <i>dermoskeleton</i> are the supratemporals,
+supraorbitals, suborbitals, and labials.</p>
+
+<p>B. In the second method of classifying the bones of the skull
+prominence is given to the facts of their different origin as
+ascertained by a study of their development. The parts developed from
+the primordial skull, or the cartilaginous case protecting the nervous
+centre are distinguished from those which enclose and support the
+commencement of the alimentary canal and the respiratory apparatus, and
+which, consisting of several arches, are comprised under the common
+name of<span class="pagenum" id="Page_87">[87]</span> <i>visceral skeleton of the skull</i>. Further, a distinction
+is made between the bones preformed in cartilage and those originating
+in tegumentary or membranous tissue. It is admitted that the primordial
+cranium is a coalition of several segments, the number of which is
+determined by that of the visceral arches, these representing the hæmal
+arches of the vertebral column; but the membrane-bones are excluded
+from a consideration of the vertebral division of the primordial skull,
+as elements originally independent of it, although these additions have
+entered into special relations to the cartilage-bones.</p>
+
+<p>With these views the bones of the Teleosteous skull are classified
+thus:—</p>
+
+<p>1. <i>Cartilage-bones of the primordial skull</i>.—The
+<i>basi-occipital</i> (5 in Figs. <a href="#fig23">23–26</a>) has retained the form of
+a vertebral centrum; it is generally concave behind, the concavity
+containing remains of the notochord; rarely a rounded articulary
+head of the first vertebra fits into it, as in <i>Symbranchus</i>,
+and still more rarely it is provided with such an articulary head
+(<i>Fistularia</i>); frequently it shows two excavations on its
+inner surface for the reception of the <i>saccus vestibuli</i>.
+The <i>exoccipitals</i> (10) are situated on the side of the
+basi-occipital, and contribute the greater portion of the periphery of
+the foramen magnum; frequently they articulate with the first vertebra,
+or meet in the upper median line, so as to exclude the supraoccipital
+from the foramen magnum. The <i>supraoccipital</i> (8) is intercalated
+between the exoccipitals, and forms a most prominent part by the median
+crest, which sometimes extends far forwards on the upper side of the
+skull, and offers attachment to the dorsal portion of the large lateral
+muscle of the trunk. When the interior portions of this bone remain
+cartilaginous, some part of the semicircular canals may be lodged in it.</p>
+
+<p>The region of the skull which succeeds the bones described encloses at
+least the greater portion of the labyrinth, and its component parts
+have been named with reference to it by<span class="pagenum" id="Page_88">[88]</span> some anatomists.<a id="FNanchor_8" href="#Footnote_8" class="fnanchor">[8]</a> The
+<i>alisphenoids</i> (11) (<i>Prooticum</i>) form sutures posteriorly
+with the basi- and exoccipitals, and meet each other in the median line
+at the bottom of the cerebral cavity; they contribute to the formation
+of a hollow in which the hypophysis cerebri and the saccus vasculosus
+are received; in conjunction with the exoccipital it forms another
+hollow for the reception of the vestibulum; generally it is perforated
+by the Trigeminal and Facial nerves. The <i>paroccipitals</i>
+(9) (<i>Epioticum</i>) lodge a portion of the posterior vertical
+semicircular canal, and form a projection of the skull on each side
+of the occipital crest, to which a terminal branch of the scapular
+arch is attached. The <i>Mastoid</i> (12 + 13) (<i>Opisthoticum</i>)
+occupies the postero-external projection of the head; it encloses a
+part of the external semicircular canal; is generally coalesced with a
+membrane-bone, the superficial <i>squamosal</i>, which emits a process
+for the suspension of the scapular arch, and is frequently, as in the
+Perch, divided into two separate bones.</p>
+
+<p>The anterior portion of the skull varies greatly as regards form, which
+is chiefly dependent on the extent of the cerebral cavity; if the
+latter is advanced far forwards, the lateral walls of the primordial
+cranium are protected by more developed ossifications than if the
+cerebral cavity is shortened by the presence of a wide and deep orbit.
+In the latter case parts which normally form the side of the skull are
+situated in front of the brain-case, between it and the orbit, and
+generally reduced in extent, often replaced by membranes; especially
+the interorbital septum may be reduced to membrane. The most constant
+ossifications of this part of the skull are the <i>orbitosphenoids</i>
+(14), which join the upper anterior margin of the alisphenoids. They
+vary much with regard to their development—they are small in Gadoids;
+larger in the Perch, Pike, Salmonoids, Macrodon, and the Clupeoids;
+and<span class="pagenum" id="Page_89">[89]</span> very large in Cyprinoids and Siluroids, in which they contribute
+to the formation of the side of the brain-case. The single Y-shaped
+<i>Sphenoideum anterius</i> (15) is as frequently absent as present; it
+forms the anterior margin of the fossa for the hypophysis. Finally, the
+<i>postfrontal</i> (4) belongs also to this group of cartilage-bones.</p>
+
+<p>The centre of the foremost part of the skull is occupied by the
+<i>ethmoid</i> (3), which shows great variations as regards its extent
+and the degree of ossification; it may extend backwards into the
+interorbital septum, and reach the orbitosphenoids, or may be confined
+to the extremity of the skull; it may remain entirely cartilaginous,
+or ossify into a lamina which separates the two orbits and encloses
+an anterior prolongation of the brain-case, along which the olfactory
+nerves pass: modifications occurring again in higher vertebrates. A
+paired ossification attached to the fore-part of the ethmoid is the
+<i>pre-frontals</i> (2), which form the base of the nasal fossa.</p>
+
+<p>2. <i>Membrane-bones attached to the primordial skull</i>.—To this
+group belong the <i>parietals</i> (7) and <i>frontals</i> (1).
+The <i>squamosal</i> (12) has been mentioned above in connection
+with the mastoid. The <i>supraorbital</i> is always small, and
+frequently absent. The lower surface of the skull is protected by the
+<i>basisphenoid</i> (parasphenoid) (6) and the <i>vomer</i> (16), both
+of which, especially the latter, may be armed with teeth.<a id="FNanchor_9" href="#Footnote_9" class="fnanchor">[9]</a></p>
+
+<p>3. <i>Cartilage bones of the alimentary portion of the visceral
+skeleton of the skull</i>.—The suspensorium consists of three
+cartilage-bones, and affords a base for the opercular apparatus
+as well as a point of attachment to the hyoid, whilst in front it
+is connected with the palato-pterygo-palatine arch. They are the
+<i>hyomandibular</i> (23), <i>symplectic</i> (31), and <i>quadrate</i><span class="pagenum" id="Page_90">[90]</span>
+(26), connected by means of the <i>metapterygoid</i> (27) with the
+<i>ecto-</i> (24) and <i>ento-pterygoid</i> (25), the foremost bone
+of the arch being the <i>palatine</i> (22). All these bones have
+been sufficiently described above (p. 55), and it remains only to be
+mentioned that the bones of the palatine arch are but rarely absent,
+as for instance in <i>Murænophis</i>; and that the symplectic does
+not extend to the articulary of the mandible, as in <i>Amia</i> and
+<i>Lepidosteus</i>, though its suspensory relation to the Meckelian
+cartilage is still indicated by a ligament which connects the two
+pieces. Of the mandibulary bones the <i>articulary</i> (35) is
+distinctly part of Meckel’s cartilage. Frequently another portion of
+cartilage below the articulary remains persistent, or is replaced by a
+separate membrane-bone, the angular.</p>
+
+<p>4. <i>Membrane-bones of the alimentary portion of the visceral
+skeleton of the skull</i>.—The suspensorium has one tegumentary bone
+attached to it, viz. the <i>præoperculum</i> (30); it is but rarely
+absent, for instance in <i>Murænophis</i>. The <i>premaxillary</i>
+(17) and <i>maxillary</i> (18) of the Teleostei appear to be also
+membrane-bones, although they are clearly analogous to the upper
+labial cartilages of the Sharks. The premaxillaries sometimes coalesce
+into a single piece (as in <i>Diodon</i>, <i>Mormyrus</i>), or they
+are firmly united with the maxillaries (as in all <i>Gymnodonts</i>,
+<i>Serrasalmo</i>, etc.) The relative position and connection of
+these two bones differs much, and is a valuable character in the
+discrimination of the various families. In some, the front margin of
+the jaw is formed by the premaxillary only, the two bones having a
+parallel position, as it has been described in the Perch (p. 53); in
+others, the premaxillary is shortened, allowing the maxillary to enter,
+and to complete, the margin of the upper jaw; and finally, in many no
+part of the maxillary is situated behind the premaxillary, but the
+entire bone is attached to the end of the premaxillary, forming its
+continuation. In<span class="pagenum" id="Page_91">[91]</span> the last case the maxillary may be quite abortive.
+The mobility of the upper jaw is greatest in those fishes in which the
+premaxillary alone forms its margin. The form of the premaxillary is
+subject to great variation: the beak of <i>Belone</i>, <i>Xiphias</i>
+is formed by the prolonged and coalesced premaxillaries. The maxillary
+consists sometimes of one piece, sometimes of two or three. The
+principal membrane-bone of the mandible is the <i>dentary</i> (34),
+to which is added the <i>angular</i> (36) and rarely a smaller one,
+the <i>splenial</i> or os <i>operculare</i>, which is situated at the
+inside of the articulary.</p>
+
+<p>5. <i>Cartilage-bones of the respiratory portion of the visceral
+skeleton of the skull.</i>—With few exceptions all the ossifications
+of the hyoid and branchial arches, as described above (p. 58), belong
+to this group.</p>
+
+<p>6. <i>Membrane-bones of the respiratory portion of the visceral
+skeleton of the skull.</i>—They are the following: the opercular
+pieces, viz. <i>operculum</i> (28), <i>sub-operculum</i> (32), and
+<i>interoperculum</i> (33). The last of these is the least constant; it
+may be entirely absent, and represented by a ligament extending from
+the mandible to the hyoid. The <i>urohyal</i> (42) which separates the
+musculi sternohyoidei, and serves for an increased surface of their
+insertion; and finally the <i>branchiostegals</i> (43), which vary
+greatly in number, but are always fixed to the cerato- and epi-hyals.</p>
+
+<p>7. <i>Dermal bones of the skull.</i>—To this category are referred
+some bones which are ossifications of, and belong to, the cutis. They
+are the <i>turbinals</i> (20), the <i>suborbitals</i> (19), and the
+<i>supratemporals</i>. They vary much with regard to the degree in
+which they are developed, and are rarely entirely absent. Nearly always
+they are wholly or partly transformed into tubes or hollows, in which
+the muciferous canals with their numerous nerves are lodged. Those
+in the temporal and scapulary regions are not always developed; on
+the other hand, the series of those ossicles may be continued on<span class="pagenum" id="Page_92">[92]</span> to
+the trunk, accompanying the lateral line. In many fishes those of the
+infraorbital ring are much dilated, protecting the entire space between
+the orbit and the rim of the præoperculum; in others, especially
+those which have the angle of the præoperculum armed with a powerful
+spine, the infraorbital ring emits a process towards the spine, which
+thus serves as a stay or support of this weapon (<i>Scorpænidæ</i>,
+<i>Cottidæ</i>).</p>
+
+<p>The <i>pectoral</i> arch of the Teleosteous fishes exhibits but
+a remnant of a primordial cartilage, which is replaced by two
+ossifications,<a id="FNanchor_10" href="#Footnote_10" class="fnanchor">[10]</a> the <i>coracoid</i> (51) and <i>scapula</i> (52);
+they offer posteriorly attachment to two series of short rods, of
+which the proximal are nearly always ossified, whilst the distal
+frequently remain small cartilaginous nodules hidden in the base of
+the pectoral rays. The bones, by which this portion is connected with
+the skull, are membrane-bones, viz. the <i>clavicle</i> (49), with
+the <i>postclavicle</i> (49 + 50), the <i>supraclavicle</i> (47), and
+<i>post-temporal</i> (46). The order of their arrangement in the Perch
+has been described above (p. 59). However, many Teleosteous fish lack
+pectoral fins, and in them the pectoral arch is frequently more or
+less reduced or rudimentary, as in many species of <i>Murænidæ</i>.
+In others the membrane-bones are exceedingly strong, contributing to
+the outer protective armour of the fish, and then the clavicles are
+generally suturally connected in the median line. The postclavicula
+and the supraclavicula may be absent. Only exceptionally the
+shoulder-girdle is not suspended from the skull, but from the anterior
+portion of the spinous column (<i>Symbranchidæ</i>, <i>Murænidæ</i>,
+<i>Notacanthidæ</i>). The number of basal elements of each of the two
+series never exceeds five, but may be less; and the distal series is
+absent in Siluroids.</p>
+
+<p>The <i>pubic</i> bones of the Teleosteous fishes undergo many
+modifications of form in the various families, but they are essentially
+of the same simple type as in the Perch.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_93">[93]</span></p>
+
+<h2 class="smaller">CHAPTER V.<br>
+<span class="subhed">MYOLOGY.</span></h2></div>
+
+<p>In the lowest vertebrate, <i>Branchiostoma</i>, the whole of the
+<i>muscular</i> mass is arranged in a longitudinal band running along
+each side of the body; it is vertically divided into a number of flakes
+or segments (<i>myocommas</i>) by aponeurotic septa, which serve as the
+surfaces of insertion to the muscular fibres. But this muscular band
+has no connection with the notochord except in its foremost portion,
+where some relation has been formed to the visceral skeleton. A very
+thin muscular layer covers the abdomen.</p>
+
+<p>Also in the <i>Cyclostomes</i> the greatest portion of the muscular
+system is without direct relation to the skeleton, and, again, it is
+only on the skull and visceral skeleton where distinct muscles have
+been differentiated for special functions.</p>
+
+<p>To the development of the skeleton in the more highly organised fishes
+corresponds a similar development of the muscles; and the maxillary and
+branchial apparatus, the pectoral and ventral fins, the vertical fins,
+and especially the caudal, possess a separate system of muscles. But
+the most noteworthy is the muscle covering the sides of the trunk and
+tail (already noticed in <i>Branchiostoma</i>), which Cuvier described
+as the “great lateral muscle,” and which, in the higher fishes, is a
+compound of many smaller segments, corresponding in number with the
+vertebræ. Each lateral muscle is divided by a median longitudinal
+groove into a dorsal and ventral half; the depression in its middle
+is<span class="pagenum" id="Page_94">[94]</span> filled by an embryonal muscular substance which contains a large
+quantity of fat and blood-vessels, and therefore differs from ordinary
+muscle by its softer consistency, and by its colour which is reddish
+or grayish. Superficially the lateral muscle appears crossed by a
+number of white parallel tendinous zig-zag stripes, forming generally
+three angles, of which the upper and lower point backwards, the middle
+one forwards. These are the outer edges of the aponeurotic septa
+between the myocommas. Each septum is attached to the middle and the
+apophyses of a vertebra, and, in the abdominal region, to its rib;
+frequently the septa receive additional support by the existence of
+epipleural spines. The fibres of each myocomma run straight and nearly
+horizontally from one septum to the next; they are grouped so as to
+form semiconical masses, of which the upper and lower have their apices
+turned backwards, whilst the middle cone, formed by the contiguous
+parts of the preceding, has its apex directed forward; this fits into
+the interspace between the antecedent upper and lower cones, the apices
+of which reciprocally enter the depressions in the succeeding segment,
+whereby all the segments are firmly locked together (<i>Owen</i>).</p>
+
+<p>In connection with the muscles reference has to be made to the
+<i>Electric organs</i> with which certain fishes are provided, as it is
+more than probable, not only from the examination of peculiar muscular
+organs occurring in the Rays, <i>Mormyrus</i>, and <i>Gymnarchus</i>
+(the function of which is still conjectural), but especially from
+the researches into the development of the electric organ of
+<i>Torpedo</i>, that the electric organs have been developed out of
+muscular substance. The fishes possessing fully developed electric
+organs, with the power of accumulating electric force and communicating
+it in the form of shocks to other animals, are the electric Rays
+(<i>Torpedinidæ</i>), the electric Sheath-fish of tropical Africa
+(<i>Malapterurus</i>), and the electric Eel of tropical America<span class="pagenum" id="Page_95">[95]</span>
+(<i>Gymnotus</i>). The structure and arrangement of the electric organ
+is very different in these fishes, and will be subsequently described
+in the special account of the several species.</p>
+
+<p>The phenomena attending the exercise of this extraordinary faculty
+also closely resemble muscular action. The time and strength of the
+discharge are entirely under the control of the fish. The power is
+exhausted after some time, and it needs repose and nourishment to
+restore it. If the electric nerves are cut and divided from the brain
+the cerebral action is interrupted, and no irritant to the body has any
+effect to excite electric discharge; but if their ends be irritated
+the discharge takes place, just as a muscle is excited to contraction
+under similar circumstances. And, singularly enough, the application
+of strychnine causes simultaneously a tetanic state of the muscles and
+a rapid succession of involuntary electric discharges. The strength of
+the discharges depends entirely on the size, health, and energy of the
+fish: an observation entirely agreeing with that made on the efficacy
+of snake-poison. Like this latter, the property of the electric force
+serves two ends in the economy of the animals which are endowed with
+it; it is essential and necessary to them for overpowering, stunning,
+or killing the creatures on which they feed, whilst incidentally they
+use it as the means of defending themselves from their enemies.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_96">[96]</span></p>
+
+<h2 class="smaller">CHAPTER VI.<br>
+<span class="subhed">NEUROLOGY.</span></h2></div>
+
+<p>The most simple condition of the nervous central organ known in
+Vertebrates is found in <i>Branchiostoma</i>. In this fish the spinal
+chord tapers at both ends, an anterior cerebral swelling, or anything
+approaching a brain, being absent. It is band-like along its middle
+third, and groups of darker cells mark the origins of the fifty or
+sixty pairs of nerves which accompany the intermuscular septa, and
+divide into a dorsal and ventral branch, as in other fishes. The two
+anterior pairs pass to the membranous parts above the mouth, and supply
+with nerve filaments a ciliated depression near the extremity of the
+fish, which is considered to be an olfactory organ, and two pigment
+spots, the rudiments of eyes. An auditory organ is absent.</p>
+
+<p>The <i>spinal chord</i> of the <i>Cyclostomes</i> is flattened in its
+whole extent, band-like, and elastic; also in <i>Chimæra</i> it is
+elastic, but flattened in its posterior portion only. In all other
+fishes it is cylindrical, non-ductile, and generally extending along
+the whole length of the spinal canal. The Plectognaths offer a singular
+exception in this respect that the spinal chord is much shortened, the
+posterior portion of the canal being occupied by a long cauda equina;
+this shortening of the spinal chord has become extreme in the Sun-fish
+(<i>Orthagoriscus</i>), in which it has shrunk into a short and conical
+appendage of the brain. Also in the Devil-fish (<i>Lophius</i>) a long
+cauda equina partly conceals the chord which terminates on the level of
+about the twelfth vertebra.</p>
+
+<p><span class="pagenum" id="Page_97">[97]</span></p>
+
+<p>The <i>brain</i> of fishes is relatively small; in the Burbot
+(<i>Lota</i>) it has been estimated to be 1/720th part of the weight of
+the entire fish, in the Pike the 1/1305th part, and in the large Sharks
+it is relatively still smaller. It never fills the entire cavity of
+the cranium; between the dura mater which adheres to the inner surface
+of the cranial cavity, and the arachnoidea which envelops the brain, a
+more or less considerable space remains, which is filled with a soft
+gelatinous mass generally containing a large quantity of fat. It has
+been observed that this space is much less in young specimens than in
+adult, which proves that the brain of fishes does not grow in the same
+proportion as the rest of the body; and, indeed, its size is nearly the
+same in individuals of which one is double the bulk of the other.</p>
+
+  <div class="figcenter" id="fig41" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig41.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 41.—Brain of Perch.</p>
+     <p class="p0 center smaller">I. Upper aspect. II. Lower aspect.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, cerebellum; <i>b</i>, optic lobes; <i>c</i>,
+hemispheres; <i>e</i>, lobi inferiores; <i>f</i>, hypophysis;
+<i>g</i>, lobi posteriores; <i>i</i>, Olfactory lobes; <i>n</i>,
+<i>N.</i> opticus; <i>o</i>, <i>N.</i> olfactorius; <i>p</i>,
+<i>N.</i> oculo-motorius; <i>q</i>, <i>N.</i> trochlearis;
+<i>r</i>, <i>N.</i> trigeminus; <i>s</i>, <i>N.</i> acusticus;
+<i>t</i>, <i>N.</i> vagus; <i>u</i>, <i>N.</i> abducens;
+<i>v</i>, Fourth ventricle.</p>
+  </div>
+
+<p>The brain of <i>Osseous fishes</i> (Fig. <a href="#fig41">41</a>) viewed from above shows
+three protuberances, respectively termed <i>prosencephalon</i>,
+<i>mesencephalon</i>, and <i>metencephalon</i>, the two anterior of
+which are paired, the hindmost being single. The foremost pair are the
+<i>hemispheres</i>, which are solid in their interior, and provided
+with two swellings in front, the <i>olfactory lobes</i>. The second
+pair are the <i>optic lobes</i>, which generally are larger than
+the hemispheres, and succeeded by the third single portion, <i>the
+cerebellum</i>. In the fresh state the hemispheres are of a grayish
+colour, and often show some shallow depressions on their<span class="pagenum" id="Page_98">[98]</span> surface; a
+narrow commissure of white colour connects them with each other. The
+optic lobes possess a cavity (<i>ventriculus lobioptici</i>), at the
+bottom of which some protuberances of variable development represent
+the corpora quadrigemina of higher animals. On the lower surface of
+the base of the optic lobes, behind the <i>crura cerebri</i>, two
+swellings are observed, the <i>lobi inferiores</i>, which slightly
+diverge in front for the passage of the <i>infundibulum</i>, from
+which a generally large <i>hypophysis</i> or <i>pituitary gland</i> is
+suspended. The relative size of the cerebellum varies greatly in the
+different osseous fishes: in the Tunny and Silurus it is so large as
+nearly to cover the optic lobes; sometimes distinct transverse grooves
+and a median longitudinal groove are visible. The cerebellum possesses
+in its interior a cavity which communicates with the anterior part of
+the fourth ventricle. The <i>medulla oblongata</i> is broader than
+the spinal chord, and contains the <i>fourth ventricle</i>, which
+forms the continuation of the central canal of the spinal chord. In
+most fishes a perfect roof is formed over the fourth ventricle by two
+longitudinal pads, which meet each other in the median line (<i>lobi
+posteriores</i>), and but rarely it remains open along its upper
+surface.</p>
+
+<p>The brain of <i>Ganoid fishes</i> shows great similarity to that of the
+Teleostei; however, there is considerable diversity of the arrangement
+of its various portions in the different types. In the Sturgeons and
+<i>Polypterus</i> (Fig. <a href="#fig42">42</a>) the hemispheres are more or less remote
+from the mesencephalon, so that in an upper view the crura cerebri,
+with the intermediate entrance into the third ventricle (<i>fissura
+cerebri magna</i>), may be seen. A vascular membranous sac, containing
+lymphatic fluid (<i>epiphysis</i>), takes its origin from the third
+ventricle, its base being expanded over the anterior interspace of the
+optic lobes, and the apex being fixed to the cartilaginous roof of the
+cranium. This structure is not peculiar to the Ganoids, but found in
+various stages of development in Teleosteans, marking,<span class="pagenum" id="Page_99">[99]</span> when present,
+the boundary between prosencephalon and mesencephalon. The lobi optici
+are essentially as in Teleosteans. The cerebellum penetrates into
+the ventriculus lobi optici, and extends thence into the open sinus
+rhomboidalis. At its upper surface it is crossed by a commissure formed
+by the <i>corpora restiformia</i> of the medulla.</p>
+
+  <div class="figcenter" id="fig42" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig42.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 42.—Brain of Polypterus. (After Müller.)</p>
+     <p class="p0 center smaller">I., Upper; II., Lateral; III., Lower aspect.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Medulla; <i>b</i>, corpora restiformia; <i>c</i>,
+cerebellum; <i>d</i>, lobi optici; <i>e</i>, hypophysis;
+<i>f</i>, fissura cerebri magna; <i>g</i>, nervus opticus;
+<i>g</i>’, chiasma; <i>h</i>, hemispheres; <i>i</i>, lobus
+olfactorius; <i>k</i>, sinus rhomboidalis (fourth ventricle).</p>
+  </div>
+
+<p>As regards external configuration, the brain of <i>Lepidosteus</i>
+and <i>Amia</i> approach still more the Teleosteous type. The
+prosencephalon, mesencephalon, and metencephalon are contiguous, and
+the cerebellum lacks the prominent transverse commissure at its upper
+surface. The sinus rhomboidalis is open.</p>
+
+<p>The brain of the <i>Dipnoi</i> shows characters reminding us of that of
+the Ganoids as well as the Chondropterygians, <i>Ceratodus</i> agreeing
+with <i>Protopterus</i> in this respect, as in<span class="pagenum" id="Page_100">[100]</span> most other points of
+its organisation. The hemispheres form the largest part of the brain;
+they are coalescent, as in Sharks, but possess two lateral ventricles,
+the separation being externally indicated by a shallow median groove
+on the upper surface. The olfactory lobes take their origin from
+the upper anterior end of the hemispheres. Epiphysis and hypophysis
+well developed. The lobi optici are very small, and remote from the
+prosencephalon, their division into the lateral halves being indicated
+by a median groove only. The cerebellum is very small, overlying the
+front part of the sinus rhomboidalis.</p>
+
+  <div class="figcenter" id="fig43" style="max-width: 600px">
+     <img
+    class="p1"   
+    src="images/fig43.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 43.—Brain of Carcharias. (After Owen.)</p>
+     <p class="p0 p-left hangingindent smaller"><i>ac</i>, Nerv. acusticus; <i>b</i>, corpus restiforme;
+<i>c</i>, cerebellum; <i>d</i>, lobus opticus; <i>e</i>,
+hypophysis; <i>g</i>, nervus opticus; <i>h</i>, hemisphere;
+<i>i</i>, lobus olfactorius; <i>i’</i>, olfactory pedicle;
+<i>k</i>, nerv. olfactorius; <i>l</i>, epiphysis; <i>m</i>,
+nerv. oculo-motorius; <i>tr</i>, nerv. trigeminus; <i>v</i>,
+nerv. vagus.</p>
+  </div>
+
+<p>The brain of <i>Chondropterygians</i> (Fig. <a href="#fig43">43</a>) is more developed than
+that of all other fishes, and distinguished by well-marked characters.
+These are, first, the prolongation of the olfactory lobes into more or
+less long pedicles, which dilate into great ganglionic masses, where
+they come into contact with the olfactory sacs; secondly, the space
+which generally intervenes between prosencephalon and mesencephalon, as
+in some Ganoids; thirdly, the large development of the metencephalon.</p>
+
+<p>The hemispheres are generally large, coalescent, but with a median,
+longitudinal, dividing groove. Frequently their surface shows traces
+of gyrations, and when they are provided with lateral ventricles,
+tubercles representing <i>corpora striata</i> may be observed. The
+olfactory pedicles take their origin from the side of the hemispheres,
+and are frequently hollow, and if so, their cavity communicates with
+the ventricle of the hemisphere. The optic lobes are generally smaller
+than the<span class="pagenum" id="Page_101">[101]</span> hemispheres, coalescent, and provided with an upper median
+groove like the prosencephalon. At their base a pair of lobi inferiores
+are constant, with the hypophysis and <i>sacsus vasculosus</i> (a
+conglomeration of vascular loops without medullary substance) between
+them.</p>
+
+<p>The cerebellum is very large, overlying a portion of the optic lobes
+and of the sinus rhomboidalis, and is frequently transversely grooved.
+The side-walls of the fourth ventricle, which are formed by the corpora
+restiformia, are singularly folded, and appear as two pads, one on
+each side of the cerebellum (<i>lobi posteriores</i> s. <i>lobi nervi
+trigemini</i>).</p>
+
+  <div class="figcenter" id="fig44" style="max-width: 406px">
+     <img
+    class="p1"   
+    src="images/fig44.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 44.—Brain of Bdellostoma. (Enlarged, after Müller.)</p>
+     <p class="p0 center smaller">I., Upper; II., Lower aspect.&emsp;Letters as in Fig. <a href="#fig45">45</a>.</p>
+  </div>
+
+  <div class="figcenter" id="fig45" style="max-width: 351px">
+     <img
+    class="p1"   
+    src="images/fig45.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 45.—Brain of Petromyzon. (Enlarged, after Müller.)</p>
+     <p class="p0 center smaller">I., Upper; II., Lower aspect.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Medulla oblongata; <i>ac</i>, nerv. acusticus;
+<i>b</i>, corpus restiforme or rudimentary cerebellum; <i>d</i>,
+lobus ventriculi tertii; <i>d’</i>, entrance into the third
+ventricle; <i>c</i>, hypophysis; <i>fa</i>, nerv. facialis;
+<i>g</i>, nerv. opticus; <i>h</i>, hemisphere; <i>hy</i>, nerv.
+hypoglossus (so named by Müller); <i>i</i>, lobus olfactorius;
+<i>k</i>, sinus rhomboidalis; <i>l</i>, epiphysis; <i>m</i>,
+nerv. oculo-motorius; <i>q</i>, corpora quadrigemina; <i>tr</i>,
+nerv. trigeminus; <i>tro</i>, nerv. trochlearis; <i>v</i>, nerv.
+vagus.</p>
+  </div>
+
+<p>The brain of the <i>Cyclostomes</i> (Figs. <a href="#fig44">44</a>, <a href="#fig45">45</a>) represents a type
+different from that of other fishes, showing at its upper surface
+three pairs of protuberances in front of the cerebellum; they are
+all solid. Their homologies are not yet satisfactorily determined,
+parts of the Myxinoid brain having received by the same observers
+determinations very different from those given<span class="pagenum" id="Page_102">[102]</span> to the corresponding
+parts of the brain of the Lampreys. The foremost pair are the large
+olfactory tubercles, which are exceedingly large in <i>Petromyzon</i>.
+They are followed by the<span class="pagenum" id="Page_103">[103]</span> hemispheres, with a single body wedged in
+between their posterior half; in <i>Petromyzon</i>, at least, the
+vascular tissue leading to an epiphysis seems to be connected with
+this body. Then follows the lobus ventriculi tertii, distinctly
+paired in Myxinoids, less so in <i>Petromyzon</i>. The last pair are
+the <i>corpora quadrigemina</i>. According to this interpretation
+the cerebellum would be absent in Myxinoids, and represented in
+<i>Petromyzon</i> by a narrow commissure only (Fig. <a href="#fig45">45</a>, <i>b</i>),
+stretching over the foremost part of the sinus rhomboidalis. In the
+Myxinoids the <i>medulla oblongata</i> ends in two divergent swellings,
+free and obtuse at their extremity, from which most of the cerebral
+nerves take their origin.</p>
+
+
+<p>The <i>Nerves</i> which supply the organs of the head are either merely
+continuations or diverticula of the brain-substance, or proper nerves
+taking their origin from the brain, or receiving their constituent
+parts from the foremost part of the spinal chord. The number of these
+spino-cerebral nerves is always less than in the higher vertebrates,
+and their arrangement varies considerably.</p>
+
+
+<p class="center">A. <i>Nerves which are diverticula of the brain</i> (Figs. <a href="#fig41">41–45</a>).</p>
+
+<p>The <i>olfactory</i> nerves (<i>first pair</i>) always retain their
+intimate relation to the hemispheres, the ventricles of which are not
+rarely continued into the tubercle or even pedicle of the nerves. The
+different position of the olfactory tubercle has been already described
+as characteristic of some of the orders of fishes. In those fishes
+in which the tubercle is remote from the brain, the nerve which has
+entered the tubercle as a single stem leaves it split up into several
+or numerous branches, which are distributed in the nasal organ. In
+the other fishes it breaks up into branchlets spread into a fan-like
+expansion at the point, where it enters the nasal cavity. The nerve
+always passes out of the skull through the ethmoid.</p>
+
+<p><span class="pagenum" id="Page_104">[104]</span></p>
+
+<p>The <i>optic</i> nerves (<i>second pair</i>) vary in size, their
+strength corresponding to the size of the eye; they take their
+origin from the <i>lobi optici</i>, the development of which again
+is proportionate to that of the nerves. The mutual relation of the
+two nerves immediately after their origin is very characteristic of
+the sub-classes of fishes. In the <i>Cyclostomes</i> they have no
+further connection with each other, each going to the eye of its
+own side.<a id="FNanchor_11" href="#Footnote_11" class="fnanchor">[11]</a> In the <i>Teleostei</i> they simply cross each other
+(<i>decussate</i>), so that the one starting from the right half of
+the brain goes to the left eye and <i>vice versa</i>. Finally, in
+<i>Palæichthyes</i> the two nerves are fused together, immediately
+after their origin, into a <i>chiasma</i>. The nerve is cylindrical for
+some portion of its course, but in most fishes gradually changes this
+form into that of a plaited band, which is capable of separation and
+expansion. It enters the bulbus generally behind and above its axis.
+The foramen through which it leaves the skull of Teleostei is generally
+in a membranous portion of its anterior wall, or, where ossification
+has taken place, in the orbito-sphenoid.</p>
+
+
+<p class="center">B. <i>Nerves proper taking their origin from the brain</i><br>
+(Figs. <a href="#fig41">41–45</a>).</p>
+
+<p>The <i>Nervus oculorum motorius</i> (<i>third pair</i>) takes its
+origin from the Pedunculus cerebri, close behind the lobi inferiores;
+it escapes through the orbito-sphenoid, or the membrane replacing it,
+and is distributed to the musculi rectus superior, rectus internus,
+obliquus inferior, and rectus inferior. Its size corresponds to the
+development of the muscles of the eye. Consequently it is absent in
+the blind <i>Amblyopsis</i>, and the Myxinoids. In <i>Lepidosiren</i>
+the nerves supplying the muscles of the eye have no independent
+origin, but are part<span class="pagenum" id="Page_105">[105]</span> of the ophthalmic division of the Trigeminus.
+In <i>Petromyzon</i> these muscles are supplied partly from the
+Trigeminus, partly by a nerve representing the Oculo-motor and
+Trochlearis, which are fused into a common trunk.</p>
+
+<p>The <i>Nervus trochlearis</i> (<i>fourth pair</i>), if present with
+an independent origin, is always thin, taking its origin on the
+upper surface of the brain from the groove between lobus opticus and
+cerebellum; it goes to the Musculus obliquus superior of the eye.</p>
+
+
+<p class="center">C. <i>Nerves taking their origin from the Medulla oblongata</i>
+(Figs. <a href="#fig41">41–45</a>).</p>
+
+<p>The <i>Nervus abducens</i> (<i>sixth pair</i>) issues on the lower
+surface of the brain, taking its origin from the anterior pyramids of
+the Medulla oblongata, and supplies the Musculus rectus externus of the
+eye, and the muscle of the nictitating membrane of Sharks.</p>
+
+<p>The <i>Nervus trigeminus</i> (<i>fifth pair</i>) and the <i>Nervus
+facialis</i> (<i>seventh pair</i>) have their origins close
+together, and enter into intimate connection with each other. In the
+Chondropterygians and most Teleostei the number of their roots is four,
+in the Sturgeons five, and in a few Teleostei three. When there are
+four, the first issues immediately below the cerebellum from the side
+of the Medulla oblongata; it contains motory and sensory elements for
+the maxillary and suspensorial muscles, and belongs exclusively to
+the trigeminal nerve. The second root, which generally becomes free
+a little above the first, supplies especially the elements for the
+Ramus palatinus, which sometimes unites with parts of the Trigeminal,
+sometimes with the Facial nerve. The third root, if present, is very
+small, and issues immediately in front of the acustic nerve, and
+supplies part of the motor elements of the facial nerve. The fourth
+root is much stronger, sometimes double, and its<span class="pagenum" id="Page_106">[106]</span> elements pass again
+partly into the Trigeminal, partly into the Facial nerve. On the
+passage of these stems through the skull (through a foramen or foramina
+in the alisphenoid) they form a ganglionic plexus, in which the
+palatine ramus and the first stem of the Trigeminus generally possess
+discrete ganglia. The branches which issue from the plexus and belong
+exclusively to the Trigeminus, supply the organs and integuments of the
+frontal, ophthalmic, and nasal regions, and the upper and lower jaws
+with their soft parts. The Facial nerve supplies the muscles of the
+gill-cover and suspensorium, and emits a strong branch accompanying
+the Meckelian cartilage to the symphysis, and another for the hyoid
+apparatus.</p>
+
+<p>The <i>Nervus acusticus</i> (<i>eighth pair</i>) is strong, and takes
+its origin immediately behind, and in contact with, the last root of
+the seventh pair.</p>
+
+<p>The <i>Nervus glossopharyngeus</i> (<i>ninth pair</i>)<a id="FNanchor_12" href="#Footnote_12" class="fnanchor">[12]</a> takes its
+origin between the roots of the eighth and tenth nerves, and issues in
+Teleostei from the cranial cavity by a foramen of the exoccipital. In
+the Cyclostomes and Lepidosiren it is part of the Nervus vagus. It is
+distributed in the pharyngeal and lingual regions, one branch supplying
+the first branchial arch. After having left the cranial cavity it
+swells into a ganglion, which in Teleostei is always in communication
+with the sympathic nerve.</p>
+
+<p>The <i>Nervus vagus</i> or <i>pneumogastricus</i> (<i>tenth pair</i>)
+rises in all Teleostei and Palæichthyes with two discrete strong roots:
+the first constantly from the swellings of the corpora restiformia,
+be they thinner or thicker and overlying the sinus rhomboidalis, or
+be they developed into lateral plaited pads, as in Acipenser and
+Chondropterygians. The second much thicker root rises from the lower
+tracts of the medulla oblongata. Both stems leave the cranial cavity by
+a common foramen,<span class="pagenum" id="Page_107">[107]</span> situated in Teleosteous fishes in the exoccipital;
+and form ganglionic swellings, of which those of the lower stem are the
+more conspicuous. The lower stem has mixed elements, motory as well as
+sensory, and is distributed to the muscles of the branchial arches and
+pharynx, the œsophagus and stomach; it sends filaments to the heart
+and to the air-bladder where it exists. The first (upper) stem forms
+the <i>Nervus lateralis</i>. This nerve, which accompanies the lateral
+mucous system of the trunk and tail, is either a single longitudinal
+stem, gradually becoming thinner behind, running superficially below
+the skin (Salmonidæ, Cyclopterus), or deeply between the muscles
+(Sharks, Chimæra), or divided into two parallel branches (most
+Teleostei): thus in the Perch there are two branches on each side, the
+superficial of which supplies the lateral line, whilst the deep-seated
+branch communicates with the spinal nerves and supplies the septa
+between the myocommas and the skin. In fishes which lack the lateral
+muciferous system and possess hard integuments, as the Ostracions, the
+lateral nerve is more or less rudimentary. It is entirely absent in
+Myxinoids, but the gastric branches of the Vagus are continued, united
+as a single nerve, along the intestine to the anus.</p>
+
+<p>No fish possesses a <i>Nervus accessorius</i>. Also a separate
+<i>Nervus hypoglossus</i> (<i>twelfth pair</i>)<a id="FNanchor_13" href="#Footnote_13" class="fnanchor">[13]</a> is absent, but
+elements from the first spinal nerve are distributed in the area
+normally supplied by this nerve in higher vertebrates.</p>
+
+<hr class="tb">
+
+<p>The number of <i>Spinal</i> nerves corresponds to that of the vertebræ,
+through or between which they pass out. Each nerve has two roots,
+an anterior and posterior, the former of which has no ganglion, and
+exclusively contains motor elements. The posterior or dorsal has a
+ganglionic enlargement,<span class="pagenum" id="Page_108">[108]</span> and contains sensory elements only. After
+leaving the vertebral canal each spinal nerve usually divides into
+a dorsal and ventral branch. The Gadoids show that peculiarity that
+each of the posterior roots of some or many of the spinal nerves
+possesses two separate threads, each of which has a ganglion of its
+own; the one of these threads joins the dorsal and the other the
+ventral branch. In fishes in which the spinal chord is very short, as
+in Plectognaths, Lophius, the roots of the nerves are extremely long,
+forming a thick <i>Cauda equina</i>. The additional function which
+the (five) anterior spinal nerves of <i>Trigla</i> have to perform
+in supplying the sensitive pectoral appendages and their muscles has
+caused the development of a paired series of globular swellings of the
+corresponding portion of the spinal chord. A similar structure is found
+in <i>Polynemus</i>.</p>
+
+  <div class="figcenter" id="fig46" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig46.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 46.</p>
+     <p class="p0 p-left hangingindent smaller">Brain and anterior portion of the spinal chord of Trigla
+(Gurnard), showing the globular swellings at the base of the
+anterior spinal nerves.</p>
+  </div>
+
+<p>A <i>Sympathic nervous</i> system appears to be absent in
+<i>Branchiostoma</i>, and has not yet been clearly made out in
+<i>Cyclostomes</i>. It is well developed in the <i>Palæichthyes</i>,
+but without cephalic portion. This latter is present in all Osseous
+fishes, in which communication of the Sympathic has been found to exist
+with all cerebral nerves, except the olfactory, optic, and acustic.
+The sympathic trunks run along each side of the aorta and the back of
+the abdomen into the hæmal canal; communicate in their course with the
+ventral branches of each of the spinal nerves; and, finally, often
+blend together into a common trunk beneath the tail. At the points of
+communication with the cerebral and spinal nerves frequently ganglia
+are developed, from which nerves emerge which are distributed to the
+various viscera.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_109">[109]</span></p>
+
+<h2 class="smaller">CHAPTER VII.<br>
+<span class="subhed">THE ORGANS OF SENSE.</span></h2></div>
+
+<p>Characteristic of the <i>Organ of Smell</i> in Fishes is that it has
+no relation whatever to the respiratory function, with the exception
+of the <i>Dipnoi</i>, in which possibly part of the water received for
+respiration passes through the nasal sac.</p>
+
+<p>The olfactory organ is single in <i>Branchiostoma</i> and the
+<i>Cyclostomes</i>. In the former a small depression on the front end
+of the body, clothed with a ciliated epithelium, is regarded as a
+rudimentary organ of smell. In the adult <i>Petromyzon</i> a membranous
+tube leads from the single opening on the top of the head into the
+cartilaginous olfactory capsule, the inside of which is clothed by
+membranes prolonged into a posterior blind tube (Fig. <a href="#fig30">30</a>, <i>s</i>),
+which penetrates the cartilaginous roof of the palate, but not the
+mucous membrane of the buccal cavity. In the Myxinoids the outer tube
+is strengthened by cartilaginous rings like a trachea; the capsule is
+lined by a longitudinally folded pituitary membrane, and the posterior
+tube opens backwards on the roof of the mouth; the opening is provided
+with a valve.</p>
+
+<p>In all other Fishes the organ of smell is double, one being on each
+side; it consists of a sac lined with a pituitary membrane, and
+without, or with one or two, openings. The position of these openings
+is very different in the various orders or suborders of Fishes.</p>
+
+<p>In the <i>Dipnoi</i> the nasal sac opens downwards by two wide openings
+which are within the boundaries of the cavity of the<span class="pagenum" id="Page_110">[110]</span> mouth. The
+pituitary membrane is transversely folded, the transverse folds being
+divided by one longitudinal fold. The walls of the sac are strengthened
+by sundry small cartilages.</p>
+
+<p>Also in <i>Chondropterygians</i> the openings, of which there is one
+to each sac, are on the lower part of the snout, and in the Rays,
+Holocephali, and some Sharks, each extends into the cleft of the mouth.
+The openings are protected by valvular flaps, supported by small
+cartilages, and moved by muscles, whence it may be concluded that these
+fishes are able to scent (actively) as well as to smell (passively).</p>
+
+  <div class="figcenter" id="fig47" style="max-width: 315px">
+     <img
+    class="p1"   
+    src="images/fig47.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 47.—Nostrils of <i>Raia lemprieri</i>, with nasal
+flaps reverted.</p>
+  </div>
+
+<p>In the majority of <i>Teleostei</i> the olfactory capsules are lateral
+or superior on the snout, covered externally by the skin, each usually
+pierced by two openings, which are either close together, or more or
+less remote from each other; the posterior is generally open, the
+anterior provided with a valve or tube. In the <i>Chromides</i> and
+<i>Labroidei ctenoidei</i> a single opening only exists for each
+sac. In the <i>Murænidæ</i> the two openings of each side are either
+superior, or lateral, or labial, that is, they are continued downwards
+and pierce the margin of the upper lip. In many Tetrodonts nasal
+openings are absent, and replaced by a conical papilla, in which the
+olfactory nerve terminates.</p>
+
+<p>It is certain that fishes possess the faculty of perceiving odours,
+and that various scents attract or repel them. A mangled carcase
+or fresh blood attracts Sharks as well as the<span class="pagenum" id="Page_111">[111]</span> voracious Serrasal
+monoids of the South American rivers. There is no reason to doubt that
+the seat of that perception is in the olfactory sac; and it may be
+reasonably conjectured that its strength depends mainly on the degree
+of development indicated by the number and extent of the interior folds
+of the pituitary membrane.</p>
+
+<p><i>Organ of Sight</i>.—The position, direction, and dimensions of the
+eyes of fishes vary greatly. In some they have an upward aspect, and
+are often very close together; in others they are lateral, and in a
+few they are even directed downwards. The Flat-fishes represent the
+extraordinary anomaly that both eyes are on the same side of the head,
+and rarely on the same level, one being generally placed more forward
+than the other. In certain species of marine fishes the eyes are of
+an extraordinary size, a peculiarity indicating that the fish either
+lives at a great depth, to which only a small proportion of the rays
+of light penetrate, or that it is of nocturnal habits. In fishes which
+have descended to such great depths that no rays whatever can reach
+them, or in freshwater fishes living in caves, or in species which
+grovel and live constantly in mud, the eyes are more or less aborted,
+sometimes quite rudimentary, and covered by the skin. In very few this
+organ appears to be entirely absent. In some Gobioids and Trachinoids
+(<i>Periophthalmus</i>, <i>Boleophthalmus</i>, <i>Uronoscopus</i>,
+etc.) the eyes, which are on the upper side of the head, can be
+elevated and depressed at the will of the fish. In the range of their
+vision and acuteness of sight, Fishes are very inferior to the higher
+classes of Vertebrates, yet at the same time it is evident that they
+perceive their prey or approaching danger from a considerable distance;
+and it would appear that the visual powers of a <i>Periophthalmus</i>,
+when hunting insects on mud-flats of the tropical coasts, are quite
+equal to that of a frog. Again, the discrimination with which fishes
+sometimes prefer one colour or kind of artificial fly to another
+affords<span class="pagenum" id="Page_112">[112]</span> sufficient evidence that the vision, at least of certain
+species is by no means devoid of clearness and precision.</p>
+
+<p>The eye of <i>Branchiostoma</i> is of the most rudimentary condition.
+It is simply a minute speck coated by dark pigment, and receiving
+the end of a short nerve. In <i>Myxinoids</i> the minute rudiment of
+the eye is covered by the skin and muscles. This is also the case
+in many of the blind Teleosteous fishes; however, whilst in the
+former fishes the organ of sight has not attained to any degree of
+development, the rudimentary eye of blind Teleostei is a retrogressive
+formation, in which often a lens and other portions of the eye can
+be recognised. In fishes with a well-developed eye it is imbedded in
+a layer of gelatinous and adipose substance, which covers the cavity
+of the orbit. A lacrymal gland is absent. In the orbit of one fish
+only, <i>Chorismodentex</i>, an organ has been found which can be
+compared to a <i>saccus lacrymalis</i>. It is a round, blind, wide
+sac, of the size of a pea, situated below the anterior corner of
+the orbit, between the maxillary bone and the muscles of the cheek,
+communicating by a rather wide foramen with the orbital cavity. The
+membrane by which it is formed is continuous with that coating the
+orbita. In the Chondropterygians the eyeball is supported by and moves
+on a cartilaginous peduncle of the orbital wall. In the majority
+of Teleosteans, and in Acipenser, a fibrous ligament attaches the
+sclerotic to the wall of the orbit. The proper muscles of the eyeball
+exist in all fishes, and consist of the four <i>Musculi recti</i>
+and the two <i>M. obliqui</i>. In many Teleostei the former rise
+from a subcranial canal, the origin of the <i>M. rectus externus</i>
+being prolonged farthest backwards. The <i>Recti</i> muscles are
+extraordinarily long in the Hammerheaded Sharks, in which they extend
+from the basis cranii along the lateral prolongations of the head to
+the eyes, which are situated at the extremities of the hammer.</p>
+
+<p>In all fishes the general integument of the head passes<span class="pagenum" id="Page_113">[113]</span> over the
+eye, and becomes transparent where it enters the orbit; sometimes it
+simply passes over the orbit, sometimes it forms a circular fold. The
+anterior and posterior portions may be especially broad and the seat
+of an adipose deposit (<i>adipose eyelids</i>), as in <i>Scomber</i>,
+<i>Caranx</i>, <i>Mugil</i>, etc. In many of these fishes the extent
+of these eyelids varies with the seasons; during the spawning season
+they are so much loaded with fat as nearly to hide the whole eye. Many
+Sharks possess a <i>nictitating</i> membrane, developed from the lower
+part of the palpebral fold, and moved by a proper set of muscles.</p>
+
+  <div class="figcenter" id="fig48" style="max-width: 282px">
+     <img
+    class="p1"   
+    src="images/fig48.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 48.</p>
+     <p class="p0 center smaller">Vertical section through eye of Xiphias. (After Owen.)</p>
+     <p class="p0 p-left hangingindent smaller"><i>co</i>, Cornea; <i>sc</i>, sclerotica; <i>o</i>, nervus
+opticus; <i>c</i>, sclerotic capsule; <i>a</i>, membrana
+argentea; <i>v</i>, membrana vasculosa; <i>u</i>, membrana uvea;
+<i>ch</i>, choroid gland; <i>r</i>, retina; <i>f</i>, processus
+falciformis; <i>h</i>, humor vitreus; <i>l</i>, lens; <i>i</i>,
+iris.</p>
+  </div>
+
+<p>The form of the <i>bulbus</i> (Fig. <a href="#fig48">48</a>) is subhemispherical, the cornea
+(<i>co</i>) being flat. If it were convex, as in higher Vertebrates,
+it would be more liable to injury; but being level with the side
+of the head the chances of injury by friction are diminished. The
+<i>sclerotica</i> (<i>sc</i>) is cartilaginous in Chondropterygians
+and Acipensers, fibrous and of varying thickness in Teleosteans, in
+the majority of which it is supported by a pair of cartilaginous
+or ossified hemispheroid cups (<i>c</i>). In a few fishes, as in
+<i>Ceratodus</i>, <i>Xiphias</i>, the cups are confluent into one
+cup, which possesses a foramen behind to allow the passage of the
+optic nerve (<i>o</i>). The <i>cornea</i> of <i>Anableps</i> shows an
+unique peculiarity. It is crossed by a dark horizontal stripe of the
+conjunctiva, dividing it into an upper and lower portion; also the iris
+is perforated by two pupils. This fish is observed to swim frequently
+with half of its head out of the water, and it is a fact that it can
+see out of the water as well as in it.</p>
+
+<p>The membranes situated between the sclerotica and retina are
+collectively called <i>choroidea</i>, and<span class="pagenum" id="Page_114">[114]</span> three in number. The one
+in immediate contact with the sclerotic, and continued upon the iris,
+is by no means constantly present; it is the <i>membrana argentea</i>
+(<i>a</i>), and composed of microscopical crystals reflecting a silvery
+or sometimes golden lustre. The middle layer is the <i>membrana
+vasculosa</i> s. <i>halleri</i> (<i>v</i>), the chief seat of the
+ramifications of the choroid vessels; the innermost layer is the
+<i>membrana ruyscheana</i> or <i>uvea</i> (<i>u</i>), which is composed
+of hexagonal pigment-cells, usually of a deep brown or black colour.</p>
+
+<p>In many <i>Teleostei</i> a <i>rete mirabile</i> surrounds the entry
+of the optic nerve; it is situated between the membrana argentea and
+vasculosa, and called the <i>choroid gland</i> (<i>ch</i>). It receives
+its arterial blood from the artery issuing from the pseudobranchia;
+the presence of a choroid gland always being combined with that of
+a pseudobranchia. Teleosteans without pseudobranchia lack a choroid
+gland. In the Palæichthyes, on the other hand, the pseudobranchia is
+present and a choroid gland absent.</p>
+
+<p>The <i>iris</i> (<i>i</i>) is merely the continuation of the choroid
+membrane; its capability of contracting and expanding is much more
+limited than in higher Vertebrates. The <i>pupil</i> is generally
+round, sometimes horizontally or vertically elliptical, sometimes
+fringed. In the Rays and Pleuronectidæ a lobe descends from the upper
+margin of the pupil, and the outer integument overlying this lobe is
+coloured and non-transparent; a structure evidently preventing light
+from entering the eye from above.</p>
+
+<p>In most <i>Teleostei</i> a fold of the <i>Choroidea</i>, called the
+<i>Processus falciformis</i> (<i>f</i>), extends from the vicinity of
+the entrance of the optic nerve to the lens. It seems to be constantly
+absent in Ganoids.</p>
+
+<p>The <i>retina</i> (<i>r</i>) is the membrane into which the optic nerve
+penetrates, and in which its terminal filaments are distributed. It
+consists of several layers (Fig. <a href="#fig49">49</a>). The outermost<span class="pagenum" id="Page_115">[115]</span> is an extremely
+delicate membrane (<i>a</i>), followed by a layer of nerve-cells
+(<i>b</i>), from which the terminal filaments issue, passing through
+several granular strata (<i>c</i>, <i>d</i>, <i>e</i>), on which the
+innermost stratum rests. This stratum is composed of cylindrical rods
+(<i>f</i>) vertically arranged, between which twin fusiform corpuscles
+(<i>g</i>) are intercalated. This last layer is thickly covered with
+a dark pigment. The retina extends over a portion of the iris, and a
+well-defined raised rim runs along its anterior margin.</p>
+
+  <div class="figcenter" id="fig49" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig49.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 49.—Vertical section of the Retina of the Perch,
+magn. X 350.</p>
+  </div>
+
+<p>The <i>vitreous humour</i> (Fig. <a href="#fig48">48</a>, <i>h</i>) which fills the
+posterior cavity of the eyeball, is of a firmer consistency than in the
+higher Vertebrates. The <i>lens</i> is spherical, or nearly so; firm,
+denser towards the centre, and lies in a hollow of the vitreous humour.
+When a falciform process is present, it is with one end attached to
+the lens, which is thus steadied in its position. It consists of
+concentric layers consisting of fibres, which in the nucleus of the
+body have marginal teeth, by which they are interlocked together. In
+<i>Petromyzon</i> this serrature is absent, or but faintly indicated.</p>
+
+  <div class="figcenter" id="fig50" style="max-width: 290px">
+     <img
+    class="p1"   
+    src="images/fig50.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 50.—Interlocking fibres of lens, highly magnified.</p>
+  </div>
+
+<p>The anterior cavity of the eye is very small in Fishes, in consequence
+of the small degree of convexity of the cornea; the quantity of the
+aqueous humour, therefore, is very small, just sufficient to float the
+free border of the iris; and the lessened<span class="pagenum" id="Page_116">[116]</span> refractive power of the
+aqueous humour is compensated by the greater convexity of the lens.</p>
+
+<hr class="tb">
+
+<p><i>Organ of Hearing.</i>—No trace of an organ of hearing has been
+found in <i>Branchiostoma</i>. In the <i>Cyclostomes</i> the labyrinth
+is enclosed in externally visible cartilaginous capsules laterally
+attached to the skull; it consists of a single <i>semicircular
+canal</i> in the Myxinoids, whilst the Petromyzontes possess two
+semicircular canals with a <i>vestibulum</i>.</p>
+
+<p>In all other fishes the labyrinth consists of a vestibule and three
+semicircular canals, the vestibule dilating into one or more sacs which
+contain the otoliths. A tympanum, tympanic cavity, and external parts,
+are entirely absent in the class of fishes.</p>
+
+<p>In the <i>Chondropterygians</i> and <i>Dipnoi</i>, the labyrinth is
+enclosed in the cartilaginous substance of the skull. In the former the
+excavation in the cartilage is larger than the membranous labyrinth,
+but nearly corresponds to it in form; the part which receives the
+membranous vestibulum is called <i>Vestibulum cartilagineum</i>, from
+which a canal issues and penetrates to the surface of the skull, where
+it is closed by the skin in Sharks, but opens by a minute foramen in
+Rays. The otolithic contents are soft and chalklike.</p>
+
+<p>In the <i>Holocephali</i> part of the labyrinth is enclosed in the
+cartilage of the skull, another part being in the cranial cavity, as
+in Ganoids and Teleosteans. The membranous vestibulum is continued by
+a canal to a single opening in the roof of the skull, from which two
+smaller canals are continued to two small foramina in the skin covering
+the occipital region.</p>
+
+<p>In the <i>Teleosteans</i> the sac which contains the otoliths lies on
+each side of the base of the cranial cavity and is often divided by a
+septum into two compartments of unequal size, each containing a firm
+and solid <i>otolith</i>; these bodies (Fig. <a href="#fig51">51</a>), possess indented
+margins, frequently other impressions<span class="pagenum" id="Page_117">[117]</span> and grooves, in which nerves
+from the N. acusticus are lodged; they vary much in size and form,
+but in both respects show a remarkable constancy in the same kind of
+fishes. The vestibule is outwards in contact with the osseous side wall
+of the skull, inwards with the metencephalon and medulla oblongata; it
+contains another firm concretion, and opens by five foramina into the
+three semicircular canals. The terminations of the acustic nerve are
+distributed over the vestibular concretion and the ampulliform ends
+(Fig. <a href="#fig52">52</a> <i>p</i>) of the semicircular canals, without being continued
+into the latter, which are filled with fluid. The semicircular canals
+(Fig. <a href="#fig52">52</a> <i>g</i>), are sometimes lodged in the cranial bones,
+sometimes partly free in the cranial cavity. Many Teleostei have
+fontanelles in the roof of the skull, closed by skin or very thin bone
+only at the place where the auditory organ approaches the surface, by
+which means sonorous undulations must be conducted with greater ease to
+the ear.</p>
+
+  <div class="figcenter" id="fig51" style="max-width: 333px">
+     <img
+    class="p1"   
+    src="images/fig51.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 51.—Otolith of Haddock (Gadus æglefinus). I. Outer, II.
+Inner aspect.</p>
+  </div>
+
+<p>In many Teleostei a most remarkable relation obtains between the organ
+of hearing and the air-bladder. In the most simple form this connection
+is established in Percoids and the allied families, in which the two
+anterior horns of the air-bladder are attached to fontanelles of the
+occipital region of the skull, the vestibulum occupying the opposite
+side of the membrane by which the fontanelle is closed. The condition
+is similar, but more complicated in many Clupeoids. The anterior narrow
+end of the air-bladder is produced into a canal at the base of the
+skull, and divided into two very narrow branches, which again bifurcate
+and terminate in a globular swelling. An appendage of the vestibulum
+meets the anterior of these swellings, and comes into close contact
+with it. Besides, the two vestibules communicate with each<span class="pagenum" id="Page_118">[118]</span> other by a
+transverse canal, crossing the cranial cavity below the brain.</p>
+
+  <div class="figcenter" id="fig52" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig52.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 52.—Communication between auditory organ and
+air-bladder in the Carp. (After E. H. Weber.)</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Basisphenoid; <i>b</i>, Occipital; <i>c</i>,
+Supraoccipital; <i>d</i>, Exoccipital; <i>e</i>, Paroccipital;
+<i>f</i>, Alisphenoid; <i>g</i>, Neural arch of first vertebra;
+<i>h</i>, <i>i</i>, <i>k</i>, second, third, and fourth
+vertebra; <i>h</i>’, <i>i</i>’, Parapophyses of second and third
+vertebra; <i>i</i>", process of the third vertebra for the
+attachment of the air-bladder; <i>k</i>, <i>l</i>, <i>m</i>,
+Chain of ossicles; <i>n</i>, Air-bladder; <i>o</i>, vestibulum;
+<i>p</i>, <i>p</i>, Ampullæ; <i>q</i>, <i>q</i>, Canales
+semicirculares; <i>r</i>, Sinus impar.</p>
+  </div>
+
+<p>The connection is effected by means of a chain of ossicles<span class="pagenum" id="Page_119">[119]</span>
+in <i>Siluridæ</i>, <i>Characinidæ</i>, <i>Cyprinidæ</i> and
+<i>Gymnotidæ</i>. A canal issues from the communication between
+vestibule and its sac, and meeting that from the other side forms with
+it a common <i>sinus impar</i> (Fig. <a href="#fig52">52</a>, <i>r</i>), lodged in the
+substance of the basi-occipital; this communicates on each side by a
+small orifice with two subspherical atria, on the body of the atlas,
+close to the foramen magnum. Each atrium is supported externally by a
+small bone (<i>m</i>); a third larger bone (<i>k</i>) completes the
+communication with the anterior part of the air-bladder. From the
+sinus impar a bifid canal penetrates into the alisphenoids, in which
+it terminates. In <i>Cobitis</i> and several Loach-like Siluroids the
+small air-bladder consists of two globular portions placed side by
+side, and wholly included within two bullæ, formed by the modified
+parapophyses of the second and third vertebræ. The three ossicles on
+each side are present, but concealed by the fore part of the osseous
+bulla.</p>
+
+<hr class="tb">
+
+<p><i>Organ of Taste.</i>—Some fishes, especially vegetable feeders, or
+those provided with broad molar-like teeth, masticate their food; and
+it may be observed in Carps and other Cyprinoid fish, that this process
+of mastication frequently takes some time. But the majority of fish
+swallow their food rapidly, and without mastication, and therefore we
+may conclude that the sense of taste cannot be acute. The tongue is
+often entirely absent, and even when it exists in its most distinct
+state, it consists merely of ligamentous or cellular substance, and
+is never furnished with muscles capable of producing the movements of
+extension or retraction as in most higher Vertebrates. A peculiar organ
+on the roof of the palate of Cyprinoids, is perhaps an organ adapted
+for perception of this sense; in these fishes the palate between and
+below the upper pharyngeal bones is cushioned with a thick, soft
+contractile substance, richly supplied with nerves from the Nervi vagus
+and glossopharyngeus.</p>
+
+<p><span class="pagenum" id="Page_120">[120]</span></p>
+
+<p><i>Organs of Touch.</i>—The faculty of touch is more developed than
+that of taste, and there are numerous fishes which possess special
+organs of touch. Most fishes are very sensitive to external touch,
+although their body may be protected by hard horny scales. They
+perceive impressions even on those parts which are covered by osseous
+scutes, in the same manner as a tortoise perceives the slightest touch
+of its carapace. The seat of the greatest sensitiveness, however,
+appears to be the snout and the labial folds surrounding the mouth.
+Many species possess soft and delicate appendages, called barbels,
+which are almost constantly in action, and clearly used as organs of
+touch. Among the <i>Triglidæ</i> and allied families, there are many
+species which have one or more rays of the pectoral fin detached from
+the membrane, and supplied with strong nerves. Such detached rays (also
+found in the <i>Polynemidæ</i>, <i>Bathypterois</i>) are used partly
+for locomotion, partly for the purpose of exploring the ground over
+which the fish moves.</p>
+
+<p>Some fish appear to be much less sensitive than others, or at least
+lose their sensitiveness under peculiar circumstances. It is well known
+that a Pike, whose mouth has been lacerated and torn by the hook,
+continues to yield to the temptation of a bait immediately afterwards.
+The Greenland Shark when feeding on the carcass of a whale allows
+itself to be repeatedly stabbed in the head without abandoning its
+prey. A pair of Congers are so dead to external impression at the time
+of copulation, and so automatically, as it were, engaged, that they
+have been taken by the hand together out of the water.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_121">[121]</span></p>
+
+<h2 class="smaller">CHAPTER VIII.<br>
+<span class="subhed">THE ORGANS OF NUTRITION AND DIGESTION.</span></h2></div>
+
+<p>Fishes are either exclusively carnivorous or herbivorous, but not a few
+feed on vegetable substances as well as animal, or on mud containing
+alimentary substance in a living or decomposing state. Generally they
+are very voracious, especially the carnivorous kinds, and the rule of
+“eat or be eaten” applies to them with unusual force. They are almost
+constantly engaged in the pursuit and capture of their prey, the
+degree of their power in these respects depending on the dimensions
+of the mouth and gullet and the strength of the teeth and jaws. If
+the teeth are sharp and hooked, they are capable of securing the most
+slender and agile animals; if this kind of teeth is combined with a
+wide gullet and distensible stomach, they are able to overpower and
+swallow other fish larger than themselves; if the teeth are broad,
+strong molars, they are able to crush the hardest aliments; if they
+are feeble, they are only serviceable in procuring some small or inert
+and unresisting prey. Teeth may be wanting altogether. Whatever the
+prey, in the majority of cases it is swallowed whole; but some of the
+most voracious fishes, like some Sharks and <i>Characinidæ</i>, are
+provided with cutting teeth, which enable them to tear their prey to
+pieces if too large to be swallowed whole. Auxiliary organs for the
+purpose of overpowering their prey, which afterwards is seized or torn
+by the teeth, like the claws of some carnivorous mammals and birds, are
+not found in this class; but in a<span class="pagenum" id="Page_122">[122]</span> few fishes the jaws themselves are
+modified for that purpose. In the Sword-fishes the bones of the upper
+jaw form a long dagger-shaped weapon, with which they not only attack
+large animals, but also frequently kill fishes on which they feed.
+The Saw-fishes are armed with a similar but still more complicated
+weapon, the saw, which is armed on each side with large teeth implanted
+in deep sockets, specially adapted for killing and tearing the prey
+before it is seized and masticated by the small teeth within the mouth.
+Fishes show but little choice in the selection of their food, and some
+devour their own offspring indiscriminately with other fishes. Their
+digestive powers are strong and rapid, but subject in some degree to
+the temperature, which, when sinking below a certain point, lowers the
+vital powers of these cold-blooded animals. On the whole, marine fishes
+are more voracious than those inhabiting fresh waters; and whilst the
+latter may survive total abstinence from food for weeks or months,
+the marine species succumb to hunger within a few days. The growth of
+fishes depends greatly on the nature and supply of food, and different
+individuals of the same species may exhibit a great disparity in their
+respective dimensions. They grow less rapidly and to smaller dimensions
+in small ponds or shallow streams than in large lakes and deep rivers.
+The young of coast fishes, when driven out to sea, where they find
+a much smaller supply of food, remain in an undeveloped condition,
+assuming an hydropic appearance. The growth itself seems to continue
+in most fishes for a great length of time, and we can scarcely set
+bounds to—certainly we know not with precision—the utmost range of
+the specific size of fishes. Even among species in no way remarkable
+for their dimensions we sometimes meet with old individuals, favourably
+situated, which more or less exceed the ordinary weight and measurement
+of their kind. However, there are certain evidently short-lived species
+of fishes which attain a remarkably<span class="pagenum" id="Page_123">[123]</span> uniform size within a very short
+time; for instance, the Stickleback, many species of <i>Gobius</i> and
+<i>Clupea</i>.</p>
+
+<hr class="tb">
+
+<p>The organs of nutrition, manducation, and deglutition, are lodged in
+two large cavities—an anterior (the mouth or <i>buccal cavity</i>),
+and a posterior (the <i>abdominal cavity</i>). In the former the
+alimentary organs are associated with those fulfilling the respiratory
+functions, the transmission of food to the stomach and of water to the
+gills being performed by similar acts of deglutition. The abdominal
+cavity commences immediately behind the head, so, however, that an
+extremely short thoracic cavity for the heart is partitioned off
+in front. Beside the alimentary organs it contains also those of
+the urogenital system and the air-bladder. The abdominal cavity is
+generally situated in the trunk only, but in numerous fishes it extends
+into the tail, being continued for some distance along each side of the
+hæmal apophyses.</p>
+
+<p>In numerous fishes the abdominal cavity opens outwards by one or two
+openings. A single <i>porus abdominalis</i> in front of the vent
+is found in <i>Lepidosiren</i> and some Sturgeons; a paired one,
+one on each side of the vent, in <i>Ceratodus</i>, some species of
+Sturgeon, <i>Lepidosteus</i>, <i>Polypterus</i>, <i>Amia</i>, and all
+Chondropterygians. As in these fishes semen and ova are discharged by
+proper ducts, the abdominal openings may serve for the expulsion of
+semen, and those ova only which, having lost their way to the abdominal
+aperture of the oviduct, would be retained in the abdominal cavity.
+In those <i>Teleosteans</i> which lack an oviduct a single <i>porus
+genitalis</i> opens <i>behind</i> the vent.</p>
+
+<p>The <i>mouth</i> of fishes shows extreme variation with regard to
+form, extent, and position. Generally opening in front, it may be
+turned upwards, or may lie at the lower side of the snout, as in most
+Chondropterygians, Sturgeons, and some Teleosteans. Vogt regards this
+position as a persistent fœtal condition. In most fishes the jaws are
+covered by the skin,<span class="pagenum" id="Page_124">[124]</span> which, before passing over the jaws, is often
+folded, forming more or less fleshy lips. In the Sharks the skin
+retains its external character even within the teeth, but in other
+fishes it changes into a mucous membrane. A <i>tongue</i> may exist as
+a more or less free and short projection, formed by the glosso*-hyal
+and a soft covering, or may be entirely absent. <i>Salivary</i> glands
+and a <i>velum palati</i> are absent in fishes.</p>
+
+<p>With regard to the <i>dentition</i>, the class of Fishes offers an
+amount of variation such as is not found in any of the other classes
+of Vertebrates. As the teeth form one of the most important elements
+in the classification of fishes, their special arrangement and form
+will be referred to in the account of the various families and genera.
+Whilst not a few fishes are entirely edentulous, in others most of the
+bones of the buccal cavity, or some of them, may be toothed, as the
+bones of the jaws, the palatines, pterygoids, vomers, basisphenoid,
+glossohyal, branchial arches, upper and lower pharyngeals. In others
+teeth may be found fixed in some portion of the buccal membrane without
+being supported by underlying bone or cartilage; or the teeth have
+been developed in membrane overlying one of the dentigerous bones
+mentioned, without having become anchylosed to the bone. When the tooth
+is fixed to the bone the attachment has generally been effected by the
+ossification of the bone of the tooth, but in some fishes a process of
+the bone projects into the cavity of the tooth; in others the teeth are
+implanted in alveoli. In these, again, frequently a process of bone
+rises from the bottom, on which the tooth rests.</p>
+
+<p>Many fishes, especially predatory fishes with long, lancet-shaped
+teeth, have all or some of the teeth capable of being bent inwards
+towards the mouth. Such “hinged” teeth resume at once the upright
+position when pressure is removed from them. They are, however,
+depressible in one direction only, thus offering no obstacle to
+the ingress, but opposing the<span class="pagenum" id="Page_125">[125]</span> egress of prey. Mr. C. S. Tomes has
+shown that the means by which this mechanism is worked are different
+in different fishes; for whilst, in the <i>Pediculati</i> and
+<i>Gadoids</i> (Hake) the elasticity resides solely in the tissue of
+the hinge (the tooth being as resilient as ever after everything else
+is severed), in the Pike the hinge is not in the least endowed with
+elasticity, but the bundles of fibres proceeding from the interior of
+the dentine cap are exceedingly elastic.</p>
+
+<p>As regards texture the teeth of fishes show considerable variation.
+The conical teeth of the Cyclostomes and the setiform teeth of many
+Teleosteans consist of a horny albuminous substance. The principal
+substance of the teeth of other fishes consists of dentine, with
+numerous dividing and anastomosing tubercles, sometimes covered
+by a stratum of unvascular dentine. An enamel-like substance has
+been observed on the crown of the teeth of <i>Sargus</i> and
+<i>Balistes</i>, and an ossification of the capsule of their matrix
+covers the enamel with a thin coating of cement. The teeth either
+possess a cavity in which the matrix is received, or, more frequently,
+they are solid, in which case vascular canals of the underlying bone
+are continued into the substance of the tooth. In the teeth of some
+fishes numerous sets of canals and tubes are so arranged that they do
+not anastomose with one another, each set being surrounded by a layer
+of dentine and cement. These apparently simple teeth are evidently
+composed of numerous small teeth, and called <i>compound</i> teeth.</p>
+
+<p>The teeth may be, and generally are, very different as regards size or
+form in the different parts of the mouth; they may be also different
+according to the age or sex of the fish (<i>Raja</i>). The teeth may
+be few in number and <i>isolated</i>, or placed in a single, double,
+or triple <i>series</i>, <i>distant</i> from one another or <i>closely
+set</i>; they may form narrow or broad <i>bands</i>, or <i>patches</i>
+of various forms. As regards form, they may be cylindrical or conical,
+pointed, straight, or curved, with or<span class="pagenum" id="Page_126">[126]</span> without an angular bent near
+their base; some are compressed laterally or from the front backwards;
+the latter may be triangular in shape, or truncated at the top like
+incisors of mammals; they may have one apex (cusp) only, or be bi- or
+tri-lobate (bi- or tri-cuspid); or have the margins denticulated or
+serrated. Compressed teeth may be confluent, and form a cutting edge in
+both jaws, which assume the shape of a parrot’s beak (Fig. <a href="#fig53">53</a>). In some
+the apex is hooked or provided with barbs. Again, some teeth are broad,
+with flat or convex surface, like molar teeth. With regard to size,
+the finest teeth are like fine flexible bristles, <i>ciliiform</i> or
+<i>setiform</i>; or, if very short and anchylosed to the bone, they
+appear only as inconspicuous asperities of the bone. Very fine conical
+teeth arranged in a band are termed <i>villiform</i> teeth; when they
+are coarser, or mixed with coarser teeth, they are <i>card-like</i>
+(dents en rape or en cardes) (Fig. <a href="#fig54">54</a>); molar-like teeth of very small
+size are termed <i>granular</i>.</p>
+
+  <div class="figcenter" id="fig53" style="max-width: 436px">
+     <img
+    class="p1"   
+    src="images/fig53.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 53.—Jaws of Calliodon.</p>
+  </div>
+
+<p>In all fishes the teeth are constantly shed or renewed during the
+whole course of their life. In fishes which have compound teeth, as
+the Dipnoi, Chimæroids, Scari,<a id="FNanchor_14" href="#Footnote_14" class="fnanchor">[14]</a> Gymnodonts, as well as in those
+which have apparently permanent teeth, as in the saw of <i>Pristis</i>,
+the detrition of the surface is made up by a constant growth of the
+tooth from its base. When the teeth are implanted in alveoli, they
+are generally succeeded by others in the vertical direction, but in
+others they succeed one another, side by side. In the majority of<span class="pagenum" id="Page_127">[127]</span>
+fishes the new tooth is not developed (as in reptiles and mammals) in
+a diverticulum of the sack of its predecessor, but like this from the
+free surface of the buccal membrane. Generally there are more than one
+tooth growing, which are in various stages of development, and destined
+to replace the one in function. This is very conspicuous in Sharks,
+in which the whole phalanx of their numerous teeth is ever marching
+slowly forwards (or in some backwards), in rotatory progress, over the
+alveolar border of the jaw, the teeth being successively cast off after
+having reached the outer margin, and fulfilled for a longer and shorter
+period their special function.</p>
+
+<div class="blockquot">
+
+<p>[The richest materials for our knowledge of the teeth of fishes
+are contained in <i>Owen’s</i> “Odontography.” Lond. 1840. 8vo.]</p>
+</div>
+
+  <div class="figcenter" id="fig54" style="max-width: 222px">
+     <img
+    class="p1"   
+    src="images/fig54.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 54.—Cardlike teeth of Plectropoma dentex, with
+canines.</p>
+  </div>
+
+<p>The <i>intestinal tract</i> is divided into four portions: œsophagus,
+stomach, small and large intestine; two or more of these divisions
+may coalesce in fishes and become indistinguishable. But it is
+characteristic of the class that the urinary apertures are constantly
+situated behind the termination of the intestinal tract.</p>
+
+<p>In <i>Branchiostoma</i> the whole intestinal tract is straight, and
+coated with a ciliated mucous membrane. The wide pharynx passes into a
+narrow œsophagus, this into a gastric cavity, the remainder being again
+narrower and terminating in the anal aperture, which lies somewhat
+to the left of the median line. The liver is represented by a green
+coloured<span class="pagenum" id="Page_128">[128]</span> cœcal diverticulum of the stomachic dilatation. A mesenterium
+is absent.</p>
+
+<p>In the <i>Cyclostomi</i> the intestinal tract is likewise straight, and
+without clearly defined divisions; however, in <i>Petromyzon</i> the
+œsophagus shows numerous longitudinal folds, and the intestine proper
+is provided with a single longitudinal fold. A mesentery, which is
+present in the Myxinoids, is represented by a short median fold only,
+by means of which the hindmost part of the intestine is fixed.</p>
+
+<p>The <i>Palæichthyes</i> show differences in the structure of
+their intestinal tract as considerable as are found among the
+<i>Teleostei</i>, but they have that in common that the absorbent
+surface of their intestine is enlarged by the development of a spiral
+valve, evidence of the presence of which in extinct Palæichthyes is
+still preserved in the fossilised fæces or <i>coproliths</i>, so
+abundant in some of the older strata.</p>
+
+<p>In <i>Chondropterygians</i> (Fig. <a href="#fig55">55</a>) the stomach is divided into a
+cardiac and pyloric portion, the former frequently terminating in a
+blind sac, and the latter varying in length. The pyloric portion is
+bent at its origin and end, and separated from the short duodenum
+(called <i>Bursa entiana</i> in these fishes) by a valve; the ductus
+hepaticus and pancreaticus enter the duodenum. This is succeeded by
+the straight intestine provided with the spiral valve, the coils
+of which may be either longitudinal and wound vertically about the
+axis of the intestine, as in <i>Carcharias</i>, <i>Galeocerdo</i>,
+<i>Thalassorhinus</i>, and <i>Zygœna</i>, or they may be transverse
+to that axis, as in the other genera. The number of gyrations in
+the latter case varies: there may be as many as forty. The short
+rectum passes into a cloaca, which contains also the orifices of the
+urogenital ducts. Only the commencement and end of the intestinal tract
+are fixed by mesenterial folds.</p>
+
+<p>In the <i>Holocephali</i> and <i>Dipnoi</i>, the intestinal tract is
+short, straight, and wide, without stomachic dilatation, a pyloric<span class="pagenum" id="Page_129">[129]</span>
+valve, close to which the ductus choledochus enters, indicating
+the boundary of the intestine proper (Fig. <a href="#fig57">57</a>, <i>p</i>). The
+spiral valve is perfect, and makes from three (<i>Chimæra</i>)
+to nine (<i>Ceratodus</i>) gyrations. A cloaca is present, as in
+Chondropterygians. A mesentery fixing the dorsal side of the intestine
+is absent.</p>
+
+  <div class="figcenter" id="fig55" style="max-width: 421px">
+     <img
+    class="p1"   
+    src="images/fig55.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 55.—Siphonal stomach and spiral valve of
+Basking-Shark (Selache). (After Home and Owen.)</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Œsophagus; <i>b</i>, Cardiac portion of stomach; <i>c</i>,
+pyloric portion; <i>d</i>, pouch intermediate between stomach and
+duodenum, with circular valves at both ends; <i>e</i>, Duodenum;
+<i>f</i>, Valve of intestine; <i>g</i>, Ductus hepaticus; <i>h</i>,
+Spleen.</p>
+  </div>
+
+<p>The other <i>Ganoids</i> resemble again more the Chondropterygians
+in the structure of their intestinal tract. The stomach has always a
+distinct pyloric portion, and has a still more complicated structure
+in <i>Acipenser</i>. The duodenal portion receives the contents of
+<i>Appendices pyloricæ</i>, which are confluent into a gland-like mass
+in <i>Acipenser</i>, but separate in <i>Polyodon</i>, and numerous and
+short in <i>Lepidosteus</i>, whilst <i>Polypterus</i> possesses one
+such appendage only. A spiral valve is developed in the Sturgeons and
+Polypterus, but in <i>Amia</i>, in which the intestine performs several
+convolutions,<span class="pagenum" id="Page_130">[130]</span> the four gyrations of the valve are situated far back
+towards the end of the intestine. In <i>Lepidosteus</i> the valve is
+rudimentary, and indicated only by three raised lines crossing the
+terminal portion of the intestine. In all these Ganoids the rectum has
+a separate opening, without cloaca.</p>
+
+<p>The structure of the intestinal tract of <i>Teleosteous</i> fishes
+is subject to so numerous modifications that we should go beyond the
+limits of the present work if we would attempt to enter into details.
+Great differences in this respect may be found even in groups of the
+same natural families. Frequently the intestinal tract remains of
+nearly the same width throughout its course, and only the entrance
+of the various ducts serves as a guide for the distinction of its
+divisions. An intestine of such uniform width may be straight and
+short, as in <i>Scombresocidæ</i>, <i>Symbranchidæ</i>, or it may
+be more or less convoluted and long, as in many <i>Cyprinidæ</i>,
+<i>Doradina</i>, etc. On the whole, carnivorous fishes have a much
+shorter and simpler intestinal tract than herbivorous.</p>
+
+<p>In the majority of Teleosteans, however, œsophagus, stomach, duodenum,
+small intestine and rectum, can be more or less distinctly, even
+externally distinguished.</p>
+
+<p>There are two predominant forms of the stomach, intermediate forms
+being, however, numerous. In the first, the <i>siphonal</i>, it
+presents the form of a bent tube or canal, one-half of the horse-shoe
+being the cardiac, the other the pyloric portion. In the second, the
+<i>cæcal</i>, the cardiac division is prolonged into a long descending
+blind sac, the cardiac and pyloric openings of the stomach lying close
+together (<i>Clupea</i>, <i>Scomber</i>, <i>Thynnus</i>, etc.)</p>
+
+<p><span class="pagenum" id="Page_131">[131]</span></p>
+
+  <div class="figcenter" id="fig56" style="max-width: 350px">
+     <img
+    class="p1"   
+    src="images/fig56.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 56.—Siphonal Stomach and Pyloric Appendages of
+a Female Salmon, 3⅓ feet long. <i>a a a</i>, Pyloric appendages;
+<i>ch</i>, ductus choledochus; <i>oe</i>, œsophagus; <i>st</i>, lower
+end of stomach; <i>p</i>, pyloric region; <i>i</i>, ascending; and
+<i>í’</i>, descending portion of intestine.</p>
+  </div>
+
+<p>The duodenum receives always the hepatic and pancreatic secretions,
+and, besides, those of the appendices pyloricæ, which, in varying
+numbers (from 1 to 200), are of very common occurrence in Teleosteans
+(Fig. <a href="#fig56">56</a>). They vary also in length<span class="pagenum" id="Page_132">[132]</span> and width, and whilst the
+narrowest serve only as secretory organs, the widest are frequently
+found filled with the same contents as the intestine. When few in
+number, each opens by a separate duct into the duodenum; when their
+number is greater two or more coalesce into a common duct; in the
+latter case the appendages cease to be free, and are connected with one
+another by a more or less firm tissue.</p>
+
+<p>Cœcal appendages at the end of the intestinal tract are of exceedingly
+rare occurrence in fishes (<i>Box</i>). There is no <i>cloaca</i> in
+Teleosteans.</p>
+
+<p>In the majority of Teleosteous fishes the <i>vent</i> is situated
+on the boundary between trunk and tail, behind the ventral fins. In
+a few it lies farther backwards, not far from the caudal fin; more
+frequently it is advanced forwards, under the middle of the abdomen
+or to the scapular arch. In two fishes, <i>Aphredoderus</i> and
+<i>Amblyopsis</i>, it lies before the pectoral fins.</p>
+
+<p>A peritoneum envelops all the divisions of the intestinal tract within
+the abdominal cavity. A broad, well-developed <i>omentum</i> has
+hitherto been found in <i>Gobiesox cephalus</i> only.</p>
+
+<p><i>Liver</i>.—The existence of a liver in <i>Branchiostoma</i> as a
+long diverticulum of the intestine has been mentioned above. In the
+Myxinoids the liver is divided into two glandular bodies, an anterior
+rounded smaller one, and a posterior larger one of an elongate shape.
+The gall-bladder lies between both, and receives a cystic duct from
+each of them. In the other fishes the proportionally large liver is a
+single large gland, from which only now and then small portions are
+found to be detached. It is either simple, or with a right and left
+lobe, or with a third lobe in the middle; each lobe may have incisions
+or subdivisions, which, however, are very inconstant. The liver of
+fishes is distinguished by the great quantity of fluid fat (oil) which
+it contains. The gall-bladder is but<span class="pagenum" id="Page_133">[133]</span> rarely absent, and attached to
+the right lobe, or towards the centre; however, in some fishes it
+is detached from the liver and connected with it by the cystic duct
+only. The bile may be conveyed by one or more hepatic ducts into a
+common duct which is continued towards the gall-bladder as <i>ductus
+cysticus</i>, and towards the duodenum as <i>ductus choledochus</i>; or
+some of the hepatic ducts enter directly the gall-bladder, or directly
+the duodenum, without communicating with the common duct. Individual
+variations in this respect are of common occurrence.</p>
+
+<p>A <i>pancreas</i> has been found hitherto in all Chondropterygians,
+Acipenser, and many Teleosteans. In the first it is a glandular mass
+of considerable size behind the stomach, close to the spleen; its duct
+leads into the duodenum. In the Sturgeons the pancreas is attached to
+the duodenum, and opens close to the ductus choledochus. In <i>Silurus
+glanis</i> it is very large, and the ductus choledochus passes through
+its substance; it is smaller in <i>Belone</i> and <i>Pleuronectes</i>,
+and situated in the mesentery; its duct accompanies the terminal
+portion of the ductus choledochus. In the Salmon, which possesses a
+large lobed pancreas, the duct is so intimately connected with the
+ductus choledochus that both appear externally as a single duct only.</p>
+
+<p>The <i>spleen</i>, which is substantially a lymphatic gland, may be
+mentioned here, as it is constantly situated in the immediate vicinity
+of the stomach, generally near its cardiac portion. With the exception
+of <i>Branchiostoma</i>, it is found in all fishes, and appears as a
+rounded or oblong organ of dark-red colour. In the Sharks frequently
+one or more smaller pieces are detached from the principal body. In
+the Dipnoi a thin layer of a very soft substance of brownish-black
+colour below the mucous membrane of the stomach and upper part of the
+intestine has been regarded as the homologue of the spleen (Fig. <a href="#fig57">57</a>,
+<i>m</i>). In most <i>Teleostei</i> the spleen is undivided, and<span class="pagenum" id="Page_134">[134]</span>
+appended by its vessels and a fold of the peritoneum to the pyloric
+bend of the stomach or the beginning of the intestine.</p>
+
+  <div class="figcenter" id="fig57" style="max-width: 387px">
+     <img
+    class="p1"   
+    src="images/fig57.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 57.—Upper part of Intestine of Ceratodus. The
+anterior wall of the intestine is opened, the liver (<i>c</i>) and
+gall-bladder (<i>e</i>) being drawn forward. A slit is made at
+<i>n</i>, through which part of the next compartment of the spirally
+wound intestine may be seen.</p>
+     <p class="p0 p-left hangingindent smaller"><i>é</i>, Mouth of ductus choledochus; <i>f</i>, stomach; <i>i</i>,
+adipose agglomeration; <i>l</i>, first compartment of intestinal spire;
+<i>m</i>, spleen; <i>oe</i>, lower part of œsophagus, opened; <i>p</i>,
+double pyloric fold; <i>q</i> <i>q</i>, glandular patches.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_135">[135]</span></p>
+
+<h2 class="smaller">CHAPTER IX.<br>
+<span class="subhed">ORGANS OF RESPIRATION.</span></h2></div>
+
+<p>Fishes breathe the air dissolved in water by means of gills or
+branchiæ. The oxygen consumed by them is not that which forms the
+chemical constituent of the water, but that contained in the air which
+is dissolved in water. Hence fishes transferred into water from which
+the air has been driven out by a high temperature, or in which the
+air absorbed by them is not replaced, are speedily suffocated. The
+absorption of oxygen by fishes is comparatively small, and it has been
+calculated that a man consumes 50,000 times more than is required by
+a Tench. However, some fishes evidently require a much larger supply
+of oxygen than others: Eels and Carps, and other fishes of similar
+low vitality, can survive the removal out of their elements for days,
+the small quantity of moisture retained in their gill-cavity being
+sufficient to sustain life, whilst other fishes, especially such as
+have very wide gill-openings, are immediately suffocated after being
+taken out of the water. In some fishes noted for their muscular
+activity, like the <i>Scombridæ</i>, the respiratory process is so
+energetic as to raise the temperature of their blood far beyond that
+of the medium in which they live. A few fishes, especially such as
+are periodically compelled to live in water thickened into mud by
+desiccation and vitiated by decomposing substances, breathe atmospheric
+air, and have generally special contrivances for this purpose. These
+are so much habituated to breathing air that many of them, even when<span class="pagenum" id="Page_136">[136]</span>
+brought into pure water of normal condition, are obliged to rise
+to the surface at frequent intervals to take in a quantity of air,
+and if they be kept beneath the surface by means of a gauze net,
+they perish from suffocation. The special contrivances consist of
+additional respiratory organs, lodged in cavities either adjoining the
+gill-cavity or communicating with the ventral side of the œsophagus,
+or of the air-bladder which enters upon respiratory functions (Dipnoi,
+Lepidosteus, Amia).</p>
+
+<p>The water used by fishes for respiration is received by the mouth, and
+by an action similar to that of swallowing driven to the gills, and
+expelled by the gill-openings, of which there may be one or several on
+each side behind the head; rarely one only in the median line of the
+ventral surface.</p>
+
+  <div class="figcenter" id="fig58" style="max-width: 318px">
+     <img
+    class="p1"   
+    src="images/fig58.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 58.—Fore-part of the body of an embryon of
+Carcharias, showing the branchial filaments (natural size).</p>
+  </div>
+
+<p>The <i>gills</i> or <i>branchiæ</i> consist essentially of folds of
+the mucous membrane of the gill-cavity (<i>laminæ branchiales</i>),
+in which the capillary vessels are distributed. In all fishes the<span class="pagenum" id="Page_137">[137]</span>
+gills are lodged in a cavity, but during the embryonic stage the
+Chondropterygians have the gill-laminæ prolonged into long filaments
+projecting beyond the gill-cavity (Fig. <a href="#fig58">58</a>), and in a few young Ganoids
+external gills are superadded to the internal.</p>
+
+<p>In <i>Branchiostoma</i> the dilated pharynx is perforated by numerous
+clefts, supported by cartilaginous rods (Fig. <a href="#fig29">29</a>, <i>h</i>). The water
+passes between these clefts into the peritoneal cavity, and makes its
+exit by the porus abdominalis situated considerably in advance of the
+vent. The water is propelled by cilia.</p>
+
+<p>In the <i>Cyclostomes</i> the gills of each side are lodged in a
+series of six or more antero-posteriorly compressed sacs, separated
+from each other by intervening septa. Each sac communicates by an
+inner duct with the œsophagus, the water being expelled by an outer
+duct. In <i>Bdellostoma</i> each outer duct has a separate opening,
+but in <i>Myxine</i> all the outer ducts pass outwards by one common
+gill-opening on each side. In the Lampreys the ducts are short, the
+outer ones having separate openings (Fig. <a href="#fig2">2</a>, p. 39). The inner ducts
+lead into a single diverticulum or bronchus, blind behind, situated
+below the œsophagus, and communicating in front with the pharynx, where
+it is provided with two valves by which the regurgitation of the water
+into the buccal cavity is prevented.</p>
+
+<p>The same type of branchial organs persists in <i>Chondropterygians</i>,
+which possess five, rarely six or seven, flattened pouches with
+transversely plaited walls. The septa between them are supported by
+cartilaginous filaments rising from the hyoidean and branchial arches.
+Each pouch opens by a cleft outwards, and by an aperture into the
+pharynx, without intervening ducts. The anterior wall of the first
+pouch is supported by the hyoidean arch. Between the posterior wall
+of the first and the anterior of the second sac, and between the<span class="pagenum" id="Page_138">[138]</span>
+adjacent walls of the succeeding, a branchial arch with its two series
+of radiating cartilaginous filaments is interposed. Consequently the
+first and last pouch have one set of gill-laminæ only, viz. the first
+on its posterior and the last on its anterior wall. The so-called
+<i>spiracles</i> on the upper surface of the head of Chondropterygians
+are to be referred to in connection with the respiratory organs. They
+are the external openings of a canal leading on each side into the
+pharynx, and situated generally close to and behind the orbit. They
+frequently possess valves or an irregularly indented margin, and
+are found in all species during the embryonic stage, but remaining
+persistent in a part only. The spiracles are the remains of the first
+visceral cleft of the embryo, and in the fœtal state long branchial
+filaments have been observed to protrude, as from the other branchial
+clefts.</p>
+
+<p>The <i>Holocephali</i> and <i>Ganoidei</i> show numerous deviations
+from the Chondropterygian type, all leading in the direction towards
+the Teleosteans. As a whole they take an intermediate position between
+the preceding types and the Teleosteans, but they show a great
+variation among themselves, and have in common only the imperfect
+separation of the branchial sacs and the presence of a single outer
+branchial aperture.</p>
+
+<p>In <i>Chimæra</i> the septum separating the branchial sacs is confluent
+with the wall of the gill-cavity in a part of its extent only, and
+still more imperfect is the separation of those branchial divisions in
+<i>Ceratodus</i> (Fig. <a href="#fig60">60</a>). The other Ganoids show no such division
+whatever. In <i>Chimæra</i> the first gill is incomplete (uniserial),
+and belongs to the hyoid; then follow three complete gills; the last,
+belonging to the fourth branchial arch, being again incomplete.
+<i>Acipenser</i>, <i>Scaphirhynchus</i>, <i>Lepidosiren</i>,
+<i>Protopterus</i>, and <i>Lepidosteus</i>, possess likewise an
+anterior incomplete gill (<i>opercular gill</i>), followed by four
+complete gills in the Sturgeons and <i>Lepidosteus</i>, whilst in<span class="pagenum" id="Page_139">[139]</span>
+<i>Lepidosiren</i> and <i>Protopterus</i> a part of the branchial
+arches is gill-less. In <i>Polyodon</i>, <i>Ceratodus</i>, and
+<i>Polypterus</i>, an opercular gill is absent, the two former having
+four complete gills, the latter three and a half only. <i>Spiracles</i>
+are still in some Ganoids present, viz. in the Sturgeons and
+<i>Polypterus</i>. In all the Ganoids an osseous gill-cover is now
+developed.</p>
+
+<p>In the <i>Teleostei</i> the gills with their supporting branchial
+arches lie in one undivided cavity; more or less wide clefts between
+the arches lead from the pharynx to the gills, and a more or less wide
+opening gives exit to the water after it has washed the gills. The
+interbranchial clefts have sometimes nearly the same extent as the
+branchial arches; sometimes they are reduced to small openings, the
+integuments stretching from one arch to the other. Sometimes there is
+no cleft behind the fourth arch, in which case this arch has only an
+uniserial gill developed. The gill-opening likewise varies much in its
+extent, and when reduced to a foramen may be situated at any place
+of the posterior boundary of the head. In the <i>Symbranchidæ</i>
+the gill-openings coalesce into a single narrow slit in the median
+line of the isthmus. In the majority of Teleosteans the integument of
+the concave side of the branchial arches develops a series of horny
+protuberances of various form, the so-called <i>gill-rakers</i>. They
+are destined to catch any solid corpuscles or substances which would be
+carried into the gill-cavity with the water. In some fishes they are
+setiform, and form a complete sieve, whilst in others they are merely
+rough tubercles, the action of which must be very incomplete if they
+have any function at all.</p>
+
+<p>Most Teleosteans possess four complete gills, but frequently the
+fourth arch is provided with an uniserial gill only, as mentioned
+above, or even entirely gill-less. The most imperfect gills are
+found in <i>Malthe</i>, which has two and a half gills only, and in
+<i>Amphipnous cuchia</i>, in which one small gill is fixed to the
+second arch.</p>
+
+<p><span class="pagenum" id="Page_140">[140]</span></p>
+
+<p>The gills of the Teleosteans as well as of the Ganoids are supported
+by a series of solid cartilaginous or horny pointed rods, arranged
+along the convex edges of the branchial arches. Arches bearing a
+complete gill have two series of those rods, one along each edge;
+those with uniserial gills bear one row of rods only. The rods are
+not part of the arch, but fixed in its integument, the several
+rods of one row corresponding to those of the other, forming pairs
+(<i>feuillet</i>, Cuvier) (Fig. <a href="#fig59">59</a>). Each rod is covered by a loose
+mucous membrane passing from one rod to its fellow opposite, which
+again is finely transversely plaited, the general surface being
+greatly increased by these plaits. In most Teleostei the branchial
+lamellæ are compressed, and taper towards their free end, but in the
+Lophobranchs their base is attenuated and the end enlarged. The mucous
+membrane contains the finest terminations of the vessels, which, being
+very superficial, impart the blood-red colour to living gills. The
+<i>Arteria branchialis</i>, the course of which lies in the open canal
+in the convexity of the branchial arch, emits a branch (<i>a</i>)
+for every pair of lamellæ which ascends (<i>b</i>) along the inner
+edge of the lamella, and supplies every one of the transverse plaits
+with a branchlet. The latter break up into a fine net of capillaries,
+from which the oxygenised blood is collected into venous branchlets,
+returning by the venous branch (<i>d</i>), which occupies the outer
+edge of the lamella.</p>
+
+  <div class="figcenter" id="fig59" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig59.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 59.—A pair of branchial lamellæ (magnified) of the Perch.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Branch of Arteria branchialis; <i>b</i>, Ascending
+branch of the same; <i>c</i>, Branch of Vena branchialis;
+<i>d</i>, Descending branch of the same; <i>e</i>, Transverse
+section through the branchial arch.</p>
+  </div>
+
+<p>The so-called <i>Pseudobranchiæ</i> (Fig. <a href="#fig60">60</a>) are the remains of an
+anterior gill which had respiratory functions during the embryonic
+life of the individuals. By a change in the circulatory<span class="pagenum" id="Page_141">[141]</span> system these
+organs have lost those functions, and appear in the adult fish as
+retia mirabilia, as they receive oxygenised blood, which, after having
+passed through their capillary system, is carried to other parts
+of the head. In Palæichthyes the pseudobranchia is a rete mirabile
+caroticum for the brain and eye; in Teleosteans a rete mirabile
+ophthalmicum only. Pseudobranchiæ are as frequently absent as present
+in Chondropterygians as well as Teleosteans. As to the Ganoids,
+they occur in <i>Ceratodus</i>, <i>Acipenser</i>, <i>Polyodon</i>,
+and <i>Lepidosteus</i>, and are absent in <i>Lepidosiren</i>,
+<i>Protopterus</i>, <i>Scaphirhynchus</i>, <i>Polypterus</i>, and
+<i>Amia</i>.</p>
+
+<p>In Chondropterygians and Sturgeons the pseudobranchiæ are situated
+within the spiracles; in those, in which spiracles have become
+obliterated, the pseudobranchiæ lie on the suspensorium, hidden
+below cellular tissue; but pseudobranchiæ are not necessarily
+co-existent with spiracles. In the other Ganoids and Teleosteans the
+pseudobranchiæ (Fig. <a href="#fig60">60</a>, <i>h</i>) are within the gill-cavity, near
+the base of the gill-cover; in <i>Ceratodus</i> even rudiments of the
+gill-rakers (<i>x’</i>, <i>x”</i>) belonging to this embryonic gill
+are preserved, part of them (<i>x”</i>) being attached to the hyoid
+arch. Pseudobranchiæ are frequently hidden below the integuments of the
+gill-cavity, and have the appearance of a glandular body rather than of
+a gill.</p>
+
+<div class="blockquot">
+
+<p>[See Müller, “Vergleichende Anatomie des Gefäss-systems der
+Myxinoiden;” and “Ueber den Bau und die Grenzen der Ganoiden.”]</p>
+</div>
+
+  <div class="figcenter" id="fig60" style="max-width: 276px">
+     <img
+    class="p1"   
+    src="images/fig60.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 60.—Gills of Ceratodus.</p>
+     <p class="p0 p-left hangingindent smaller"><i>x</i>, Arcus aortæ; <i>gl</i>, Glossohyal; <i>ch</i>,
+Ceratohyal; <i>u</i>, Attachment of the first gill to the
+walls of the gill-cavity; <i>h</i>, Pseudobranchia; <i>x’</i>,
+<i>x”</i>, two series of gill-rakers belonging to the
+Pseudobranchia.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_142">[142]</span></p>
+
+<p><i>Accessory respiratory organs</i> for retaining water or
+breathing air, such as are found in the <i>Labyrinthici</i>,
+<i>Ophiocephalidæ</i>, certain <i>Siluridæ</i>, and <i>Lutodira</i>,
+are structures so specialised that they are better described in the
+accounts of the Fishes in which they have been observed.</p>
+
+<hr class="tb">
+
+<p><i>Air-Bladder.</i>—The air-bladder, one of the most characteristic
+organs of fishes, is a hollow sac, formed of several tunics, containing
+gas, situated in the abdominal cavity, but without the peritoneal sac,
+entirely closed or communicating by a duct with the intestinal tract.
+Being compressible, its special functions consist in altering the
+specific gravity of the fish or in changing the centre of gravity. In a
+few fishes it assumes the function of the organ of higher Vertebrates,
+of which it is the homologue—viz. of a <i>lung</i>.</p>
+
+<p>The gas contained in the air-bladder is secreted from its inner
+surface. In most freshwater fishes it consists of nitrogen, with a very
+small quantity of oxygen and a trace of carbonic acid; in sea-fishes,
+especially those living at some depth, oxygen predominates, as much
+as 87 per cent having been found. Davy found in the air-bladder of a
+fresh-run Salmon a trace of carbonic acid and 10 per cent of oxygen,
+the remainder of the gas being nitrogen.</p>
+
+<p>An air-bladder is absent in <i>Leptocardii</i>, <i>Cyclostomi</i>,
+<i>Chondropterygii</i>, and <i>Holocephali</i>; but occurs in all
+Ganoids, in which, besides, its respiratory functions more or less
+clearly manifest themselves. Its occurrence in Teleosteans is most
+irregular, closely allied species sometimes differing from each other
+in this respect; it shows in this sub-class the most extraordinary
+modifications, but has no respiratory function whatever.</p>
+
+<p>Constantly situated within the abdominal cavity, below the vertebral
+column, but without the sac of the peritoneum which covers only its
+ventral portion, the air-bladder is frequently<span class="pagenum" id="Page_143">[143]</span> prolonged into the
+tail, the prolongation being either simple and lodged between the
+non-united parapophyses, or double and penetrating between the muscles
+and hæmapophyses of each side. In the opposite direction processes of
+the air-bladder may penetrate into the skull, as has been mentioned
+above (p. 117). In some fishes the air-bladder is almost loose in the
+abdominal cavity, whilst in others it adheres most intimately by firm
+and short tissue to the vertebral column, the walls of the abdomen, and
+the intestines. In the Cobitina and many Siluroids it is more or less
+completely enclosed in osseous capsules formed by the vertebræ.</p>
+
+<p>The tunics of the majority of air-bladders are an extremely fine
+internal one, frequently shining silvery, containing crystalline
+corpuscles, sometimes covered with a pavement-epithelium; and a thicker
+outer one of a fibrous texture, which sometimes attains to considerable
+thickness and yields isinglass. This wall is strengthened in many
+fishes by muscular layers for the compression of the whole organ or of
+some portion of it.</p>
+
+<p>A distinction has been made between air-bladders which communicate by
+a duct with the intestinal tract and those which are entirely closed.
+However, it is to be remembered that at an early stage of development
+all air-bladders are provided with such a duct, which in a part of the
+fishes more or less completely obliterates, being then represented by a
+fine ligament only. In young <i>Lucioperca</i> of six to eight inches
+in length the duct may be found still open for a considerable distance;
+and, on the other hand, in adult <i>Physostomi</i>, that is Teleosteous
+fishes with a ductus pneumaticus, not rarely the whole duct is found
+very narrow, or, for some part of its length, even entirely closed.</p>
+
+  <div class="figcenter" id="fig61" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig61.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 61.—Air-bladder of Otolithus sp.</p>
+  </div>
+
+  <div class="figcenter" id="fig62" style="max-width: 300px">
+     <img
+    class="p1"   
+    src="images/fig62.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 62.—Vertical section through abdominal cavity of
+Collichthys lucida. <i>b</i>, air-bladder; <i>l</i>, liver;
+<i>s</i>, stomach; <i>epp</i> and <i>ipp</i>, external and
+internal laminæ of peritoneum parietale; <i>epv</i> and
+<i>ipv</i>, external and internal laminæ of peritoneum
+viscerale; <i>dv</i>, dorsal air-vessels; <i>vv</i>, ventral
+air-vessels.</p>
+  </div>
+
+<p>Air-bladders without duct are found in Acanthopterygians,
+Pharyngognaths, Anacanths, and Lophobranchs. They may consist of
+a single cavity or divided by constrictions into two<span class="pagenum" id="Page_144">[144]</span> or three
+partitions situated behind one another; they may consist of two lateral
+partitions, assuming a horseshoe-like form, or they may be a single
+sac with a pair of simple or bifid processes in front or behind (Fig.
+<a href="#fig61">61</a>). The families of <i>Sciænidæ</i> and <i>Polynemidæ</i> possess
+air-bladders with a most extraordinary development of appendages
+rising from each side of the air-bladder. In the Sciænoid (Fig. <a href="#fig63">63</a>)
+fifty-two branches issue from each side, each branch being bifurcate
+and bearing smaller appendages. In <i>Pogonias chromis</i> (Fig. <a href="#fig64">64</a>)
+the sides of the anterior half is provided with irregular broad-fringed
+appendages, the hindmost of which communicates by a narrow duct
+with the posterior extremity of the air-bladder. In <i>Collichthys
+lucida</i> (Fig. <a href="#fig62">62</a>) twenty-five appendages issue from each side; the
+anterior ones are directed towards the front, but the lateral assume
+a more posterior<span class="pagenum" id="Page_145">[145]</span> direction, the nearer they are to the posterior
+extremity of the air-bladder, where they form an assemblage giving
+the appearance of a cauda equina. All these appendages soon bifurcate
+in a dorsal and ventral stem; these stems bifurcate again and again,
+and either terminate after the first or second bifurcation or are so
+far prolonged as to reach the median line of the ventral and dorsal
+sides, anastomosing with the branches of the other side. The branches
+being enveloped in laminæ of the peritonæum, form a dorsal and ventral
+sac of beautiful appearance, caused by the regular arrangement of the
+air-vessels. The dorsal sac is situated between the air-bladder and
+the roof of the abdominal cavity without being attached to the latter.
+The ventral sac receives within its cavity the intestine, liver, and
+ovaries.—A peculiar mechanism has been observed in the air-bladder of
+the <i>Ophidiidæ</i>, the anterior portion of which can be prolonged by
+the contraction of two muscles attached to its anterior extremity, with
+or without the addition of a small bone.</p>
+
+  <div class="figcenter" id="fig63" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig63.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 63.—Air-bladder of a Sciænoid.</p>
+     <p class="p0 smaller">&ensp;I. Visceral surface opened at <i>b</i>, to show openings of the
+lateral branches.</p>
+     <p class="p0 smaller">II. Isolated lateral branch; <i>a</i>, its opening into the
+cavity of the air-bladder.</p>
+  </div>
+
+<p>Air-bladders with a pneumatic duct are found in Ganoids and
+Physostomes, the duct entering the dorsal side of the intestinal
+tract, with the exception of <i>Polyp</i><i>terus</i><span class="pagenum" id="Page_146">[146]</span> and the
+<i>Dipnoi</i>, in which it enters on the ventral side of the œsophagus.
+In the majority the orifice is in the œsophagus, but in some, as in
+<i>Acipenser</i>, in the cardiac portion of the stomach, or in its
+blind sac, as in many Clupeoids. The air-bladder may be single, or
+consist of two divisions situated one behind the other (Fig. <a href="#fig52">52</a>); its
+inner surface may be perfectly smooth, or form manifold pouches and
+cells. If two divisions are present the anterior possesses a middle
+elastic membrane which is absent in the posterior; each division has
+a muscular layer, by which it can be separately compressed, so that
+part of the contents of the posterior may be driven into the elastic
+anterior division, and <i>vice versa</i>. The posterior division being
+provided with the ductus pneumaticus does not require the elasticity of
+the anterior.</p>
+
+  <div class="figcenter" id="fig64" style="max-width: 232px">
+     <img
+    class="p1"   
+    src="images/fig64.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 64.—Air-bladder of Pogonias chromis.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_147">[147]</span></p>
+
+<p>Some Siluroids possess a peculiar apparatus for voluntarily exercising
+a pressure upon the air-bladder. From the first vertebra a process
+takes its origin on each side, expanding at its end into a large round
+plate; this is applied to the side of the air-bladder, and by pressing
+upon it expels the air through the duct; the small muscle moving the
+plate rises from the skull.</p>
+
+<p>The connection of the air-bladder with the organ of hearing in some
+Physostomes has been described above, p. 117.</p>
+
+<p>In the modifications of the air-bladder, hitherto mentioned, the
+chief and most general function is a mechanical one; this organ
+serves to regulate the specific gravity of the fish, to aid it in
+maintaining a particular level in the water, in rising or sinking,
+in raising or depressing the front part of its body as occasion may
+serve. Yet a secretion of gas from the blood into its cavity must take
+place; and if this be so, it is not at all impossible that also an
+exchange of gases between the two kinds of blood is effected by means
+of the extraordinary development of <i>retia mirabilia</i> in many
+air-bladders.</p>
+
+<p>In all fishes the arteries of the air-bladder take their origin from
+the aorta or the system of the aorta, and its veins return either to
+the portal, or vertebral, or hepatic veins; like the other organs of
+the abdominal cavity it receives arterial blood and returns venous
+blood. However, in many fishes the arteries as well as veins break
+up below the inner membrane into <i>retia mirabilia</i> in various
+ways. The terminal ramifications of the arteries may dissolve into
+fan-like tufts of capillaries over almost every part of the inner
+surface, as in Cyprinoids. Or these tufts of radiating capillaries
+are more localised at various places, as in <i>Esocidæ</i>; or the
+tufts are so aggregated as to form gland-like, <i>red bodies</i>, the
+capillaries reuniting into larger vessels, which again ramify freely
+round the border of the red body; the red bodies are formed not only
+by minute arteries but also by minute veins, both freely anastomosing
+with its kind, and being inextricably interwoven.<span class="pagenum" id="Page_148">[148]</span> The rest of the
+inner surface of the air-bladder receives its blood, not from the red
+bodies, but from normally ramifying vessels. This kind of rete mirabile
+or “vaso-ganglion” is found in the Perch and Gadoids; it is generally
+distributed in closed air-bladders, but also sometimes observed in
+air-bladders’ with pneumatic duct. In <i>Anguilla</i> and <i>Conger</i>
+two similar vaso-ganglia are situated at the sides of the opening of
+the pneumatic duct.</p>
+
+  <div class="figcenter" id="fig65" style="max-width: 350px">
+     <img
+    class="p1"   
+    src="images/fig65.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 65.—Lung of Ceratodus opened in its lower half
+to show its cellular pouches. <i>a</i>, Right half; <i>b</i>, Left
+half; <i>c</i>, Cellular pouches; <i>e</i>, Vena pulmonalis; <i>f</i>,
+Arterial blood-vessel; <i>oe</i>, Œsophagus opened, to show glottis
+(<i>gl.</i>)</p>
+  </div>
+
+<p>Whilst the air-bladders of some <i>Ganoids</i>, anatomically as well
+as functionally, closely adhere to the Teleosteous type, that of
+<i>Amia</i> is more cellular and lung-like in its interior than the
+Teleosteous air-bladder, and <i>Polypterus</i> approaches the Dipnoi
+not only in having a laterally divided air-bladder but also in its
+pneumatic duct entering the <i>ventral</i> side of the œsophagus. The
+air-bladder of the <i>Dipnoi</i> possesses still more the anatomical
+characteristics of a lung and assumes its functions, though, as it
+co-exists with gills, only periodically<span class="pagenum" id="Page_149">[149]</span> or in an auxiliary manner. The
+ductus pneumaticus is a membranous bronchus, entering the ventral side
+of the œsophagus, and provided at its entrance with a <i>glottis</i>.
+In <i>Ceratodus</i> (Fig. <a href="#fig65">65</a>) the lung is still a single cavity, but
+with a symmetrical arrangement of its internal pouches; it has no
+pulmonal artery, but receives branches from the <i>arteria cœliaca</i>.
+Finally, in <i>Lepidosiren</i> and <i>Protopterus</i> the lung is
+completely divided into lateral halves, and by its cellular structure
+approaches most nearly that of a reptile; it is supplied with venous
+blood by a true pulmonary artery.</p>
+
+  <div class="figcenter" id="fig66" style="max-width: 405px">
+     <img
+    class="p1"   
+    src="images/fig66.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 66.—Heart of Lepidosteus osseus.</p>
+     <p class="p0 center smaller">I. External aspect. II. Conus arteriosus opened.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Atrium; <i>b</i>, Conus arteriosus; <i>v</i>,
+Ventricle; <i>h</i>, Branchial artery for 3d and 4th gill;
+<i>k</i>, for the second; <i>l</i>, for the first; <i>m</i>,
+branch for the opercular gill; <i>d</i>, Single valve at the
+base of the conus; <i>e-g</i>, Transverse rows of Ganoid valves.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_150">[150]</span></p>
+
+<h2 class="smaller">CHAPTER X.<br>
+<span class="subhed">ORGANS OF CIRCULATION.</span></h2></div>
+
+<p>The <i>Blood-corpuscles</i> of fishes are, with one exception, of an
+elliptic shape; this exception is <i>Petromyzon</i>, which possesses
+circular, flat, or slightly biconvex blood-corpuscles. They vary
+much in size; they are smallest in Teleosteans and Cyclostomes,
+those of <i>Acerina cernua</i> measuring 1/2461 of an inch in their
+longitudinal, and 1/3000 in their transverse diameter. As far as it is
+known at present the <i>Salmonidæ</i> have the largest blood-corpuscles
+among Teleosteans, those of the salmon measuring 1/1524 by 1/2460 in.,
+approaching those of the Sturgeon. Those of the Chondropterygians are
+still larger; and finally, <i>Lepidosiren</i> has blood-corpuscles
+not much smaller than those of Perennibranchiates, viz.—1/570 by
+1/941 in. Branchiostoma is the only fish which does not possess red
+blood-corpuscles.</p>
+
+<div class="blockquot">
+
+<p>[See G. Gulliver, “Proc. Zool. Soc.,” 1862, p. 91; and 1870, p.
+844; and 1872, p. 833.]</p>
+</div>
+
+<p>Fishes, in common with the other Vertebrates, are provided with a
+complete circulation for the body, with another equally complete for
+the organs of respiration, and with a particular abdominal circulation,
+terminating at the liver by means of the <i>vena portæ</i>; but
+their peculiar character consists in this, that the branchial
+circulation alone is provided at its base with a muscular apparatus or
+<i>heart</i>, corresponding to the right half of the heart of Mammalia
+and Birds.</p>
+
+<p>The <i>Heart</i> is situated between the branchial and abdominal
+cavities, between the two halves of the scapulary arch,<span class="pagenum" id="Page_151">[151]</span> rarely
+farther behind, as in <i>Symbranchidæ</i>. It is enclosed in a
+<i>pericardium</i>, generally entirely separated from the abdominal
+cavity by a diaphragma, which is, in fact, the anterior portion of the
+peritoneum, strengthened by aponeurotic fibres. However, in some fishes
+there is a communication between the pericardial and peritoneal sacs,
+viz. in the Chondropterygians and Acipenser, whilst in the Myxinoids
+the pericardial sac is merely a continuation of the peritoneum.</p>
+
+  <div class="figcenter" id="fig67" style="max-width: 246px">
+     <img
+    class="p1"   
+    src="images/fig67.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 67.—Heart of Ceratodus.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Atrium; <i>b</i>, Conus arteriosus; <i>d</i>,
+Papillary valve within the conus; <i>e-g</i>, Transverse rows
+of Ganoid valves; <i>h</i>, <i>i</i>, Anterior arcus aortæ;
+<i>k</i>, <i>l</i>, Posterior arcus aortæ; <i>v</i>, Ventricle.</p>
+  </div>
+
+<p>The heart is, relatively to the size of the body, very small, and
+consists of three divisions: the <i>atrium</i>, with a large <i>sinus
+venosus</i> into which the veins enter; the <i>ventricle</i>; and a
+conical hollow swelling at the beginning of the arterial system, the
+structure of which forms one of the most important characters used
+in the classification of fishes. In all <i>Palæichthyes</i> (Figs.
+<a href="#fig66">66</a> and <a href="#fig67">67</a>) this swelling is still a division of the pulsating heart,
+being provided with a thick muscular stratum; it is not separated from
+the ventricle by two valves opposite to each other, but its interior
+is fitted with a plurality of valves, arranged in transverse series
+more or less numerous in the various groups of <i>Palæichthyes</i>.
+<i>Lepidosiren</i> and <i>Protopterus</i> offer an example of a
+modification of this valvular arrangement, their valves being
+longitudinal, each valve in fact being formed by the confluence of
+several smaller ones situated behind one another. This Palæichthyan
+type is called <i>conus arteriosus</i>.</p>
+
+<p>In Cyclostomes and Teleosteans (Fig. <a href="#fig68">68</a>) the enlargement<span class="pagenum" id="Page_152">[152]</span> is a swelling
+of the artery, without muscular stratum and without contractility; with
+the exception of the Myxinoids its walls are thick, fibrous, with many
+trabeculæ and pouches, but it has no valves in its interior, and is
+separated from the ventricle by two valves opposite to each other. This
+Teleostean type is called <i>bulbus aortæ</i>.</p>
+
+  <div class="figcenter" id="fig68" style="max-width: 251px">
+     <img
+    class="p1"   
+    src="images/fig68.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 68.—Bulbus aortæ of Xiphias gladius, opened.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Section through part of the wall of ventricle;
+<i>b</i>, Section through the bulbus; <i>c</i>, Teleosteous
+valves of the ostium arteriosum; <i>d</i>, Accessory valves, of
+rudimentary nature and inconstant; <i>e</i>, Trabeculæ carneæ of
+the bulbus.</p>
+  </div>
+
+<p>The sinus venosus sends the whole of the venous blood by a single
+orifice of its anterior convexity into the atrium; two thin membranous
+valvules turned towards the atrium, prevent the blood from re-entering
+the sinus. A pair of other valves between atrium and ventricle have the
+same function. The walls of the ventricle are robust, and, internally,
+it is furnished with powerful fleshy trabeculæ.</p>
+
+<p><span class="pagenum" id="Page_153">[153]</span></p>
+
+<p>The bulbus or conus arteriosus is prolonged into the branchial artery
+which soon divides, sending off a branch to each branchial arch. On
+returning from the respiratory organ the branchial veins assume the
+structure and functions of arteries. Several branches are sent off
+to different portions of the head and to the heart, but the main
+trunks unite to form the great artery which carries the blood to the
+viscera and all the parts of the trunk and tail, and which, therefore,
+represents the <i>aorta</i> of higher animals.</p>
+
+<p>In the majority of Teleosteans the <i>aorta</i> has proper walls formed
+by its own membranes, but in the Sturgeons it is independent at its
+commencement only, and replaced by a canal formed by hæmal elements of
+the vertebral column, and clothed inside with a perichondrium. In many
+Chondropterygians and some Teleosteans (<i>Esox</i>, <i>Clupea</i>,
+<i>Silurus</i>), the aorta possesses its own firm membranes along its
+ventral side, dorsally being protected by a very thin membrane only,
+attached to the concavity of the centra of the vertebræ.</p>
+
+<p>The circulatory system of <i>Branchiostoma</i> and of the <i>Dipnoi</i>
+shows essential differences from that of other fishes.</p>
+
+<p><i>Branchiostoma</i> is the only fish which does not possess a
+muscular heart, several cardinal portions of its vascular system being
+contractile. A great vein extends forwards along the caudal region
+below the notochord, and exhibits contractility in a forward direction;
+it is bent anteriorly, passing into another tube-like pulsatile trunk,
+the branchial heart, which runs along the middle of the base of the
+pharynx, sending off branches on each side to the branchiæ; each of
+these branches has a small contractile dilatation (<i>bulbillus</i>) at
+its base. The two anterior branches pass directly into the aorta, the
+others are branchial arteries, the blood of which returns by branchial
+veins emptying into the aorta. The blood of the intestinal veins is
+collected in a contractile tube, the portal vein, situated below the
+intestine, and distributed<span class="pagenum" id="Page_154">[154]</span> over the rudimentary liver. Of all other
+fishes, only in <i>Myxinoids</i> the portal vein is contractile. All
+the blood-corpuscles of <i>Branchiostoma</i> are colourless and without
+nucleus.</p>
+
+<p>In <i>Dipnoi</i> a rudimentary division of the heart into a right and
+left partition has been observed; this is limited to the ventricle in
+<i>Ceratodus</i>, but in <i>Lepidosiren</i> and <i>Protopterus</i>
+an incomplete septum has been observed in the atrium also. All
+Dipnoi have a pulmonal vein, which enters the atrium by a separate
+opening, provided with a valve. The pulmonal artery rises in
+<i>Lepidosiren</i> and <i>Protopterus</i> from an arch of the aorta,
+but in <i>Ceratodus</i> it is merely a subordinate branch, rising from
+the <i>Arteria cœliaca</i>.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_155">[155]</span></p>
+
+<h2 class="smaller">CHAPTER XI.<br>
+<span class="subhed">URINARY ORGANS.</span></h2></div>
+
+<p>In <i>Branchiostoma</i> no urinary organs have been found.</p>
+
+<p>In Myxinoids these organs are of a very primitive structure: they
+consist of a pair of ducts, extending from the urogenital porus through
+the abdominal cavity. Each duct sends off at regular intervals from
+its outer side a short wide branch (the uriniferous tube), which
+communicates by a narrow opening with a blind sac. At the bottom of
+this sac there is a small vaso-ganglion (<i>Malpighian corpuscle</i>),
+by which the urine is secreted.</p>
+
+<p>In the Lampreys the kidneys form a continuous gland-like body, with
+irregular detached small portions. The ureters coalesce before they
+terminate in the urogenital papilla.</p>
+
+<p>In Chondropterygians the kidneys occupy the posterior half or
+two-thirds of the back of the abdominal cavity, without the sac of the
+peritoneum (as in all fishes) which forms a firm tendinous horizontal
+septum. The kidneys of the two sides are never confluent, and generally
+show a convoluted or lobulated surface. The ureters are short; each is
+dilated into a pouch, and communicating with its fellow terminates by a
+single urethra (which also receives the vasa deferentia) behind the end
+of the rectum in the large common cloaca.</p>
+
+<p>In Ganoids the kidneys occupy a similar position as in
+Chondropterygians, but these fishes differ considerably with regard
+to the termination and the arrangement of the ends of<span class="pagenum" id="Page_156">[156]</span> the urogenital
+ducts. The Dipnoi possess a cloaca. In <i>Ceratodus</i> the ureters
+open into it by a common opening, separate from the genital opening;
+and no closed urinary bladder has been developed. <i>Lepidosiren</i>
+has a small urinary bladder; the ureters do not communicate directly
+with it, but terminate separately on small papillæ in the dorsal
+compartment of the cloaca. The other Ganoids lack a cloaca, and the
+urogenital opening is behind the vent as in Teleosteans. In all the
+genital and urinary ducts coalesce towards their end. The Sturgeons
+have no urinary bladder, whilst it is present in <i>Amia</i>, the
+ureters opening separately into it.</p>
+
+<p>The <i>kidneys</i> of Teleosteans are situated likewise without the
+peritoneal cavity, immediately below some part of the vertebral column,
+and vary exceedingly with regard to form and extent. Sometimes they
+reach from the skull to between the muscles of the tail, sometimes
+they are limited to the foremost part of the abdominal cavity (in
+advance of the diaphragm), but generally their extent corresponds to
+that of the abdominal portion of the vertebral column. Frequently
+they are irregular on their dorsal surface, filling every available
+recess, flat, attenuated on the sides, more or less coalescent
+towards the middle; in other fishes they are more compact bodies. The
+ureters terminate, either separate or united, in a urinary bladder,
+varying in shape, which opens by a short urethra behind the vent. The
+urinary opening may be separate or confluent with that of the genital
+ducts, and is frequently placed on a more or less prominent papilla
+(<i>papilla urogenitalis</i>). If separate, the urinary opening is
+behind the genital; and if a papilla is developed, its extremity is
+perforated by the urethra, the genital opening being situated nearer
+the base. A few Teleosteans show an arrangement similar to that of
+Chondropterygians and Dipnoi, the urogenital openings being in the
+posterior wall of the rectum (<i>Symbranchidæ</i>, <i>Pediculati</i>,
+and some <i>Plectognathi</i>).</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_157">[157]</span></p>
+
+<h2 class="smaller">CHAPTER XII.<br>
+<span class="subhed">ORGANS OF REPRODUCTION.</span></h2></div>
+
+<p>All fishes are <i>dioecious</i>, or of distinct sex. Instances
+of so-called <i>hermaphroditism</i> are, with the exception of
+<i>Serranus</i>, abnormal individual peculiarities, and have been
+observed in the Cod-fish, some Pleuronectidæ, and in the Herring.
+Either the generative organ of one side was found to be male, that
+of the other female; or the organ of one or both sides was observed
+to have been developed partly into an ovary partly into a testicle.
+In the European species of Serranus a testicle-like body is attached
+to the lower part of the ovary; but many specimens of this genus are
+undoubtedly males, having normally developed testicles only.</p>
+
+<p>The majority of fishes are oviparous, comparatively few viviparous;
+the embryos being developed either in the ovarium or in some dilated
+portion of the oviduct. In viviparous fishes actual copulation takes
+place, and the males of most of them are provided with copulatory
+or intromittent organs. In oviparous fishes the generative products
+are, during sexual excitement, discharged into the water, a very
+small quantity of semen being sufficient for effectual impregnation
+of a number of ova dispersed in a considerable quantity of water;
+circumstances which render <i>artificial impregnation</i> more
+practicable than in any other class of animals.</p>
+
+<p>In <i>Branchiostoma</i> the generative organs occupy the ventral side
+of the abdominal cavity, into which they discharge their contents. No
+ducts are developed in either sex.</p>
+
+<p><span class="pagenum" id="Page_158">[158]</span></p>
+
+<p>In the <i>Cyclostomes</i> the generative organ is single, and fixed to
+or suspended from the median line of the back of the visceral cavity
+by a duplicature of the peritoneum (<i>mesoarium</i>); the testicle
+and ovary being distinguishable by their contents only. These escape
+by dehiscence of the cells or capsules and rupture of the peritoneal
+covering into the abdominal cavity, and are expelled by reciprocal
+pressure of the intertwined sexes through the <i>porus genitalis</i>,
+which is sunk between two labia of the skin in <i>Myxine</i>, and
+produced into a long papilla in Petromyzon.</p>
+
+  <div class="figcenter" id="fig69" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig69.jpg"
+     alt="">
+     <p class="p0 center smaller">69.—Ovum of Myxine glutinosa, enlarged.</p>
+  </div>
+
+<p>The ova of the Lampreys are small, globular, like those of Teleosteans.
+Those of Myxine have a very peculiar shape when mature; they are of an
+oval form, about 15 millimetres long and 8 millimetres broad, enveloped
+in a horny case, which at each end is provided with a bundle of short
+threads, each thread ending in a triple hook. Whilst in the mesoarial
+fold the eggs are attached to one another by means of these hooks, and
+after being expelled they probably fix themselves by the same means to
+other objects. As in all fishes producing ova of large size, the number
+of ova matured in one season is but small.</p>
+
+<p>In <i>Teleosteans</i> the generative organs are comparatively
+large. In some families the ovaries are without closed covering
+and without oviducts, as in <i>Salmonidæ</i>, <i>Galaxiidæ</i>,
+<i>Notopteridæ</i>, <i>Murænidæ</i>, and others. The surface of such
+an open ovary—as, for instance, that of the Salmon—is transversely
+plaited, the ova being developed in capsules in the stroma of the
+laminæ; after rupture of the capsules the mature ova drop into the
+abdominal cavity, and are expelled by the porus genitalis. The ovaries
+of the other Teleosteans are closed sacs, continued into oviducts.
+Frequently such ovaries<span class="pagenum" id="Page_159">[159]</span> coalesce into a single body, or one in which
+the division is effected internally only by a more or less complete
+septum. Fixed by a mesoarium, the ovaries occupy generally a position
+outwards of the intestine or air-bladder; their form varies as well
+as the thickness and firmness of their covering, which frequently
+is an extremely thin transparent membrane. The inner surface of the
+ovarian sac is transversely or longitudinally plaited or covered with
+fringes, on which the ova are developed, as in the open ovaries. In
+the viviparous Teleosteans the embryons are likewise developed within
+the ovary, notably in the <i>Embiotocidæ</i>, many <i>Blenniidæ</i>,
+and <i>Cyprinodontidæ</i>, <i>Sebastes viviparus</i>, etc. Among
+the Cyprinodonts the end of the oviduct is attached to the anterior
+anal rays, which are modified into supports of its termination. In
+<i>Rhodeus</i> the oviduct is periodically prolonged into a long
+oviferous tube, by means of which the female deposits her ova into the
+shells of living Bivalves.</p>
+
+  <div class="figcenter" id="fig70" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig70.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 70.—Ditrema argenteum, with fully developed young,
+ready for expulsion by the genital orifice, <i>o</i>; <i>a</i>, folds
+of the ovarian sac; <i>v</i>, vent.</p>
+  </div>
+
+<p>The <i>ova</i> of Teleosteous Fishes are extremely variable in size,
+quite independently of the size of the parent species. The ova of large
+and small individuals of the same species, of course, do not differ in
+size; but, on the whole larger<span class="pagenum" id="Page_160">[160]</span> individuals produce a greater number
+of ova than smaller ones of the same species. The larger the size of
+the ova is in a species, the smaller is the number produced during one
+season. The ova of the Eel are almost microscopic. The small sized roe
+in the Herring, Lump-fish, Halibut, and Cod-fish, have been estimated
+at respectively 25,000, 155,000, 3,500,000, and 9,344,000. Larger in
+size and fewer in number are those of <i>Antennarius</i>, <i>Salmo</i>,
+<i>Aspredo</i>, <i>Lophobranchs</i>, etc. Comparatively largest are
+those of <i>Gastrosteus</i>; and the Siluroid genus <i>Arius</i>, the
+males of which take care of their progeny, produces ova from 5 to 10
+millimeters in diameter. The ova of all Teleosteans are perfectly
+globular and soft-shelled. Teleosteans without oviduct, deposit them
+separated from one another; whilst in many Teleosteans with an oviduct
+the ova are enveloped in a glutinous substance, secreted by its glands,
+swelling in the water and forming lumps or cords, in which the ova are
+aggregated.</p>
+
+  <div class="figcenter" id="fig71" style="max-width: 222px">
+     <img
+    class="p1"   
+    src="images/fig71.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 71. Ovum of Arius boakii (Ceylon), showing embryo.
+Nat. size.</p>
+  </div>
+
+  <div class="figcenter" id="fig72" style="max-width: 251px">
+     <img
+    class="p1"   
+    src="images/fig72.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 72.—Abdomen of <i>Aspredo batrachus</i>, with the
+ova attached; at <i>a</i>, the ova are removed, to show the spongy
+structure of the skin, and the processes filling the interspaces
+between the ova. (Natural size.)</p>
+  </div>
+
+<p>Instances of the female taking care of her progeny are extremely scarce
+in fishes. At present only two examples are known, that of the Siluroid
+genus <i>Aspredo</i>, and of <i>Solenostoma</i>. In the former, during
+the time of propagation, the integuments of the lower side of the flat
+trunk of the female assume a soft and spongy texture. After having
+deposited the eggs, the female attaches them to, and presses them into,
+the spongy integument, by merely lying over them. She carries them on
+her belly, as the Surinam Toad (<i>Pipa</i>) carries her ova on the
+back. When the eggs are hatched the excrescence on the skin disappears,
+and the abdomen becomes as smooth as before. In <i>Solenostoma</i>
+the inner side of the long and broad ventral fins coalesces with the
+integuments of the body, a large pouch being formed for the reception
+of the eggs. There is a peculiar provision for the retention of the
+eggs<span class="pagenum" id="Page_161">[161]</span> in the sac, and probably for the attachment of the embryo. The
+inner walls of the sac are lined with long filaments,<span class="pagenum" id="Page_162">[162]</span> arranged in
+series along the ventral rays, and more numerous and longer at the
+base of the rays than in the middle of their length, behind which they
+disappear entirely. They are also more developed in examples in which
+eggs are deposited in the sac than in those which have the sac empty.
+The filaments most developed have a length of half an inch, and are
+beset with mamilliform appendages. A slightly undulated canal runs
+along the interior of the filament.</p>
+
+  <div class="figcenter" id="fig73" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig73.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 73.—Solenostoma cyanopterum ♂ (Indian Ocean).</p>
+  </div>
+
+  <div class="figcenter" id="fig74" style="max-width: 300px">
+     <img
+    class="p1"   
+    src="images/fig74.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 74.—Pouch with ova, formed by the ventral fins
+of <i>Solenostoma</i>. Lower aspect; the edges of the fins have been
+pushed aside to allow of a view of the inside of the pouch. (Natural
+size.)</p>
+  </div>
+
+<p>The <i>Testicles</i> of the <i>Teleosteans</i> are always paired,
+and occupy the same position as the ovaries. Their size varies
+extraordinarily at the different seasons of the year. Vasa deferentia
+are constant. In the males of viviparous Teleosteans the urogenital
+papilla is frequently enlarged, and clearly serves as an intromittent
+organ. In <i>Clinus despicillatus</i> the vas deferens widens
+within the abdomen into a cavity occupied by a complex network of
+loose fasciculi, rising from the mucous membrane. The cavity can be
+compressed by a special powerful muscle, the accumulated semen being
+thus expelled with considerable force through the narrow aperture
+of the penis. In many Cyprinodonts the vas deferens runs along the
+anterior anal rays, which may be thickened, and prolonged into a long
+slender organ.</p>
+
+<p><span class="pagenum" id="Page_163">[163]</span></p>
+
+<p>Many Teleostei take care of their progeny, but with the exception of
+<i>Aspredo</i> and <i>Solenostoma</i>, mentioned above (p. 160), it is
+the male on which this duty devolves. In some, as in <i>Cottus</i>,
+<i>Gastrosteus</i>, <i>Cyclopterus</i>, <i>Antennarius</i>,
+<i>Ophiocephalus</i>, <i>Callichthys</i>, the male constructs with
+more or less skill a nest, and jealously guards the ova deposited in
+it by the female. The male of some species of <i>Arius</i> carries the
+ova (Fig. <a href="#fig71">71</a>) about with him in his capacious pharynx. The species of
+<i>Chromis</i>, inhabiting the sea of Galilee, are said to take care
+of their ova in the same manner. And, finally, in the Lophobranchs,
+nature has aided this instinct by the development of a pouch on the
+abdomen or lower side of the tail. In the Syngnathidæ this pouch is
+formed by a fold of the skin developed from each side of the trunk and
+tail, the free margins of the fold being firmly united in the median
+line, whilst the eggs are being hatched in the inside of the pouch.
+In <i>Hippocampus</i> the pouch is completely closed, with a narrow
+anterior opening.</p>
+
+  <div class="figcenter" id="fig75" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig75.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 75.—Syngnathus acus ♂, with sub-caudal pouch.</p>
+  </div>
+
+  <div class="figcenter" id="fig76" style="max-width: 300px">
+     <img
+    class="p1"   
+    src="images/fig76.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 76.—Sub-caudal pouch of Syngnathus acus, with the
+young, ready to leave the pouch. One side of the membrane of the pouch
+is pushed aside to admit of a view of its interior. (Natural size.)</p>
+  </div>
+
+<p>The genital organs of <i>Ganoids</i> show similar diversity of
+structure as those of Teleosteans, but on the whole they approach<span class="pagenum" id="Page_164">[164]</span>
+the Batrachian type. The ovaries are not closed, except in
+<i>Lepidosiren</i>; all Ganoids possess oviducts. In the Sturgeons the
+oviduct as well as the vas deferens is represented by a funnel-shaped
+prolongation of the peritoneum, which communicates with the wide
+ureter. The inner aperture of the funnel is on a level of the middle
+of the testicle or ovary, the outer within the ureter; and it is a
+noteworthy fact that only at certain periods of the life of the fish
+this outer aperture is found to be open,—at other times the peritoneal
+funnel appears as a closed blind sac within the ureter. The mode of
+passage of the semen into the funnel is not known.</p>
+
+<p>In <i>Polypterus</i> and <i>Amia</i>, proper oviducts, with abdominal
+apertures in about the middle of the abdominal cavity, are developed;
+they coalesce with the ureters close to the common urogenital aperture.</p>
+
+<p>In <i>Ceratodus</i> (Fig. <a href="#fig77">77</a>), a long convoluted oviduct extends to
+the foremost limit of the abdominal cavity, where it opens by a slit
+at a considerable distance from the front end of the long ovary;
+this aperture is closed in sexually immature specimens. The oviducts
+unite close to their common opening in the cloaca. During their
+passage through the oviduct the ova receive a gelatinous covering
+secreted by its mucous membrane. This is probably also the case
+in <i>Lepidosiren</i>, which possesses a convoluted oviduct with
+secretory glands in the middle of its length. The oviduct begins with
+a funnel-shaped dilatation, and terminates in a wide pouch, which
+posteriorly communicates with that of the other side, both opening by a
+common aperture behind the urinary bladder.</p>
+
+<p>The ova of Ganoids, as far as they are known at present, are small, but
+enveloped in a gelatinous substance. In the Sturgeon have been counted
+as many as 7,635,200. Those of <i>Lepidosteus</i> seem to be the
+largest, measuring 5 millimetres in diameter with their envelope, and 3
+millimetres without it. They are deposited singly, like those of Newts.</p>
+
+<p><span class="pagenum" id="Page_165">[165]</span></p>
+
+  <div class="figcenter" id="fig77" style="max-width: 300px">
+     <img
+    class="p1"   
+    src="images/fig77.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 77.—Ovaries of Ceratodus.</p>
+     <p class="p0 p-left hangingindent smaller"><i>a</i>, Right ovary shown from the inner surface, which is
+covered by the peritoneum; <i>a’</i>, Left ovary, showing its
+outer surface; <i>l</i>, Portion of liver; <i>o</i>, Oviduct;
+<i>p</i>, the lower part of the oviduct is opened to show the
+folds of its inner membrane; <i>q</i>, Opening of the left
+oviduct into the right; <i>r</i>, Abdominal orifice of the
+oviduct.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_166">[166]</span></p>
+
+<p>In <i>Chondropterygians</i> (and <i>Holocephali</i>) the organs of
+reproduction assume a more compact form, and are more free from
+a lengthened attachment to the back of the abdominal cavity. The
+ovaries of the majority are paired, single in the <i>Carchariidæ</i>
+and <i>Scylliidæ</i>, one remaining undeveloped. But the oviducts
+are always paired, beginning immediately behind the diaphragma with
+a common aperture. They consist of two divisions, separated by a
+circular valve; the upper is narrow, and provided within its coats
+with a gland which secretes the leathery envelope in which most of
+the Chondropterygian ova are enclosed; the lower forms the uterine
+dilatation, in which the embryoes of the viviparous species are
+developed. Generally the vitelline sac of the embryoes is free, and
+without connection with the uterus, which in these cases has merely the
+function of a protecting pouch; but in Carcharias and Mustelus lævis a
+<i>placenta uterina</i> is formed, the vascular walls of the vitelline
+sac forming plaits fitting into those of the membrane of the uterus.
+The ends of the uteri open by a common aperture behind the ureter into
+the cloaca.</p>
+
+  <div class="figcenter" id="fig78" style="max-width: 516px">
+     <img
+    class="p1"   
+    src="images/fig78.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 78.—Ventral fins and claspers of Chiloscyllium
+trispeculare.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_167">[167]</span></p>
+
+<p>The testicles are always paired, rounded, and situated in the
+anterior part of the abdominal cavity, covered by the liver. <i>Vasa
+efferentia</i> pass the semen into a much-convoluted <i>epididymis</i>,
+which is continued into the <i>vas deferens</i>; this, at the
+commencement of its course, is spirally wound, but becomes straight
+behind, and has its end dilated into a seminal reservoir. It opens with
+the urethra in a papilla within the cloaca.</p>
+
+<p>The so-called <i>claspers</i> of Chondropterygians (Fig. <a href="#fig78">78</a>) are
+characteristic of all male individuals. They are semi-ossified
+appendages of the pubic, with which they are movably joined, and
+special muscles serve to regulate their movements. Sometimes they are
+armed with hook-like osseous excrescences (<i>Selache</i>). They are
+irregularly longitudinally convoluted, and, when closely ad-pressed to
+each other, form a canal open at their extremity. A gland, abundantly
+discharging a secretion during the season of propagation, is situated
+at, and opens into, the base of the canal. It is still doubtful whether
+the generally-adopted opinion that their function consists in holding
+the female during copulation is correct, or whether they are not
+rather an intromittent organ, the canal of which not only conducts the
+secretion of their proper gland but also the impregnating fluid.</p>
+
+  <div class="figcenter" id="fig79" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig79.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 79.—Egg of a Scyllium from Magelhan’s Straits (?
+Sc. chilense). Natural size.</p>
+  </div>
+
+  <div class="figcenter" id="fig80" style="max-width: 296px">
+     <img
+    class="p1"   
+    src="images/fig80.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 80.—Egg-shell of Cestracion philippi, half natural
+size, linear.</p>
+     <p class="p0 center smaller">I. External view. II. Vertical section.</p>
+     <p class="p0 center smaller"><i>a</i>, One spiral ridge; <i>b</i>, The other spiral ridge; <i>c</i>,
+Cavity for the ovum.</p>
+  </div>
+
+<p>The ova of the oviparous Chondropterygians are large and few in number;
+they are successively impregnated,<span class="pagenum" id="Page_168">[168]</span> and the impregnation must take
+place before they are invested with a tough leathery envelope which
+would be impenetrable to the semen, that is, before they enter the
+uterus; therefore, copulation must take place in all these fishes. The
+form of the egg-shell differs in the various genera; generally (Fig.
+<a href="#fig79">79</a>) they are flattened, quadrangular, with each of the four corners
+produced, and frequently prolonged into long filaments which serve for
+the attachment of the ova to other fixed objects. In <i>Notidanus</i>
+the surfaces are crossed by numerous ridges. In <i>Cestracion</i>
+(Fig. <a href="#fig80">80</a>) the egg is pyriform, with two broad ridges or plates, wound
+edgewise round it, the two ridges forming five spires. The eggs of
+<i>Callorhynchus</i><span class="pagenum" id="Page_169">[169]</span> (Fig. <a href="#fig81">81</a>) have received a protective resemblance
+to a broad-leaved fucus, forming a long depressed ellipse, with a
+plicated and fringed margin.</p>
+
+  <div class="figcenter" id="fig81" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig81.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 81.—Egg of Callorhynchus antarcticus. <i>a</i>,
+Cavity for the embryo.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_170">[170]</span></p>
+
+<h2 class="smaller">CHAPTER XIII.<br>
+<span class="subhed">GROWTH AND VARIATION OF FISHES.</span></h2></div>
+
+<p>Changes of form normally accompanying growth (after absorption of
+the vitelline sac) are observed in all fishes; but in the majority
+they affect only the proportional size of the various parts of the
+body. In young fishes the eyes are constantly larger than in adult
+relatively to the size of the head; and again, the head is larger
+relatively to that of the body. Changes amounting to metamorphosis
+have been hitherto observed in <i>Petromyzon</i> only. In the larval
+condition (<i>Ammocætes</i>) the head is very small, and the toothless
+buccal cavity is surrounded by a semicircular upper lip. The eyes are
+extremely small, hidden in a shallow groove; and the vertical fins
+form a continuous fringe. In the course of three or four years the
+teeth are developed, and the mouth changes into a perfect suctorial
+organ; the eyes grow; and the dorsal fin is divided into two divisions.
+In Malacopterygians and Anacanths the embryonal fringe from which
+the vertical fins are developed, is much longer persistent<span class="pagenum" id="Page_171">[171]</span> than in
+Acanthopterygians. A metamorphosis relating to the respiratory organs,
+as in Batrachians, is indicated in the class of Fishes by the external
+gills with which fœtal Plagiostomes (Fig. <a href="#fig58">58</a>, p. 136) and the young of
+some Ganoids, viz. the <i>Protopterus</i> and <i>Polypterus</i>, are
+provided.</p>
+
+  <div class="figcenter" id="fig82" style="max-width: 326px">
+     <img
+    class="p1"   
+    src="images/fig82.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 82.—Mouth of Larva of Petromyzon branchialis.</p>
+  </div>
+
+  <div class="figcenter" id="fig83" style="max-width: 344px">
+     <img
+    class="p1"   
+    src="images/fig83.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 83.—Mouth of Petromyzon fluviatilis.</p>
+     <p class="p0 p-left hangingindent smaller"><i>mx</i>, Maxillary tooth; <i>md</i>, Mandibulary tooth;
+<i>l</i>, Lingual tooth; <i>s</i>, Suctorial teeth.</p>
+  </div>
+
+  <div class="figcenter" id="fig84" style="max-width: 467px">
+     <img
+    class="p1"   
+    src="images/fig84.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 84.—Armature of præoperculum of young Caranx
+ferdau. (Magnified.)</p>
+     <p class="p0 center smaller">I. Of an individual, 1¼ inch long. II. Of an individual, 2 inches long.</p>
+  </div>
+
+  <div class="figcenter" id="fig85" style="max-width: 357px">
+     <img
+    class="p1"   
+    src="images/fig85.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 85.—Tholichthys osseus. Six times the natural size.</p>
+  </div>
+
+  <div class="figcenter" id="fig86" style="max-width: 301px">
+     <img
+    class="p1"   
+    src="images/fig86.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 86.—Tholichthys-stage of Heniochus (?).</p>
+  </div>
+
+  <div class="figcenter" id="fig87" style="max-width: 405px">
+     <img
+    class="p1"   
+    src="images/fig87.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 87.—Tholichthys-stage of Pomacanthus (magn.)
+Atlantic.</p>
+  </div>
+
+  <div class="figcenter" id="fig88" style="max-width: 408px">
+     <img
+    class="p1"   
+    src="images/fig88.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 88.—Young Chætodon citrinellus (30 mill. long).</p>
+  </div>
+
+<p>One of the most extraordinary changes by which, during growth, the
+form and position of several important organs are affected, occurs
+in Flat-fishes (<i>Pleuronectidæ</i>); their young are symmetrically
+formed, with a symmetrical mouth, and with one eye on each side, and,
+therefore, keep their body in a vertical position when swimming. As
+they grow they live more on the bottom, and their body, during rest,
+assumes a horizontal position; in consequence, the eye of the lower
+side moves towards the upper, which alone is coloured; and in many
+genera the mouth is twisted in the opposite direction, so that the
+bones, muscles, and teeth are much more developed on the blind side
+than on the coloured. In a great number of other <i>Teleostei</i>
+certain bones of the head show a very different form in the young
+state. Ossification proceeds in those bones in the direction of lines
+or radii which project in the form of spines or processes; as the
+interspaces between these processes are filled with bone, the processes
+disappear entirely, or at least project much less in the older than
+in the younger individuals (Fig. <a href="#fig84">84</a>). The young of some fishes may be
+armed with a long powerful præopercular or scapular spine, or show
+a serrature of which nothing remains in the<span class="pagenum" id="Page_172">[172]</span> adult fish except some
+ridges or radiating lines. These processes seem to serve as weapons
+of defence during a period in the life of the fish in which it needs
+them most. In not a few instances a portion of this armature is so
+much developed that the disappearance of its most projecting parts
+with the growth of the fish is not only due to its being surrounded
+by other bone, but, partially at least, caused by absorption. The
+<i>Carangidæ</i>, <i>Cyttidæ</i>, <i>Squamipinnes</i>, <i>Xiphiidæ</i>,
+offer instances of such remarkable changes. A fish, described as
+<i>Tholichthys osseus</i> (Fig. <a href="#fig85">85</a>), is probably the young of a
+Cyttoid, the suprascapula, humerus, and præoperculum forming enormously
+enlarged plates. In the fish Fig. <a href="#fig86">86</a> those bones appear still enlarged,
+and the frontals develop a remarkably long and curved horn above the
+orbit. In the <i>Tholichthys</i>-stage of <i>Pomacanthus</i> (specimens
+10 millimetres long, Fig. <a href="#fig87">87</a>), the frontal bone is prolonged into a
+straight lancet-shaped process, nearly half as long as the body; the
+suprascapular and præopercular processes cover<span class="pagenum" id="Page_173">[173]</span> and hide the dorsal
+and ventral fins. The plates attached to the shoulder-girdle remain
+persistent until the young fish has assumed the form of the adult;
+thus they are still visible in young <i>Chætodon citrinellus</i>, 30
+millimetres long, in which the specific characters are already fully
+developed.—The Sword-fishes with ventral fins (<i>Histiophorus</i>)
+belong to the Teleosteans of the largest size; in young individuals,
+9 millimetres long (Fig. <a href="#fig89">89</a>), both jaws are produced, and armed with
+pointed teeth; the supraorbital margin is ciliated; the parietal and
+præoperculum are prolonged into long spines; the dorsal and anal fins
+are a low fringe, and the ventrals make their appearance as a pair
+of short buds. When 14 millimetres long (Fig. <a href="#fig90">90</a>) the young fish has
+still the same armature of the head, but the dorsal fin has become much
+higher, and the ventral<span class="pagenum" id="Page_174">[174]</span> filaments have grown to a great length. At a
+third stage, when the fish has attained to a length of 60 millimetres,
+the upper jaw is considerably prolonged beyond the lower,<span class="pagenum" id="Page_175">[175]</span> losing its
+teeth; the spines of the head are shortened, and the fins assume nearly
+the shape which they retain in mature individuals. Young Sword-fishes
+without ventral fins (<i>Xiphias</i>) undergo similar changes;
+and, besides, their skin is covered with small rough excrescences
+longitudinally arranged, which continue to be visible after the young
+fish has assumed the form of the mature in other respects (Fig. <a href="#fig92">92</a>).</p>
+
+  <div class="figcenter" id="fig89" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig89.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 89.—Young Sword-fish (Histiophorus), 9 mill. long.
+Atlantic. (Magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig90" style="max-width: 492px">
+     <img
+    class="p1"   
+    src="images/fig90.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 90.—Young Sword-fish (Histiophorus), 14 mill.
+long. South Atlantic. (Magn.)</p>
+  </div>
+
+  <div class="figcenter" id="fig91" style="max-width: 657px">
+     <img
+    class="p1"   
+    src="images/fig91.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 91.—Young Sword-fish (Histiophorus), 60 mill.
+long. Mid-Atlantic.</p>
+  </div>
+
+  <div class="figcenter" id="fig92" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig92.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 92.—Xiphias gladius, young, about 8 inches long.</p>
+  </div>
+
+<p>The Plectognaths show no less extraordinary changes: an extraordinary
+form taken in the South Atlantic, and named <i>Ostracion
+boops</i>, is considered by Lütken to be the young of a Sun-fish
+(<i>Orthagoriscus</i>). In very young more advanced Sun-fishes (18
+to 32 millimetres) the vertical diameter of the body exceeds, or is
+not much less than, the longitudinal; and small conical spines are
+scattered over its various parts. The caudal fin is developed long
+after the other vertical fins.</p>
+
+  <div class="figcenter" id="fig93" style="max-width: 423px">
+     <img
+    class="p1"   
+    src="images/fig93.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 93.—“Ostracion boops” (much magnified).</p>
+  </div>
+
+  <div class="figcenter" id="fig94" style="max-width: 349px">
+     <img
+    class="p1"   
+    src="images/fig94.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 94.—Young of Orthagoriscus, 18 and 32 mill. long.
+(Natural size.)</p>
+  </div>
+
+<p><span class="pagenum" id="Page_176">[176]</span></p>
+
+<p>Similar changes take place in a number of other fishes, and in many
+cases the young are so different that they were described as distinct
+genera: thus <i>Priacantichthys</i> has proved to be the young of
+<i>Serranus</i>, <i>Rhynchichthys</i> that of <i>Holocentrum</i>,
+<i>Cephalacanthus</i> of <i>Dactylopterus</i>, <i>Dicrotus</i>
+of <i>Thyrsites</i>, <i>Nauclerus</i> of <i>Naucrates</i>,
+<i>Porthmeus</i> of <i>Chorinemus</i>, <i>Lampugus</i> of
+<i>Coryphæna</i>, <i>Acronurus</i> of <i>Acanthurus</i>, <i>Keris</i>
+of <i>Naseus</i>, <i>Porobronchus</i> of <i>Fierasfer</i>,
+<i>Couchia</i> of <i>Motella</i>, <i>Stomiasunculus</i> of
+<i>Stomias</i>, etc.</p>
+
+<p>The fins are most frequently subject to changes; but, whilst in some
+fishes parts of them are prolonged into filaments with age, in others
+the filaments exist during the early life-periods only; whilst in some
+a part of the dorsal or the ventral fins is normally developed in the
+young only, in others those very parts are peculiar to the mature age.
+The integuments are similarly altered: in some species the young only
+has asperities on the skin, in others the young are smooth and the old
+have a tubercular skin; in some the young only have a hard bony head;
+in others (some Siluroids) the osseous carapace of the head and neck,
+as it appears in the adult, is more or less covered with soft skin
+whilst the fish is young.</p>
+
+<p>In not a few fishes the external changes are in relation to the
+sexual development (<i>Callionymus</i>, many <i>Labyrinthici</i>,
+Cyprinodonts). These <i>secondary sexual differences</i> show
+themselves in the male individual, only when it commences to enter upon
+his sexual functions, and it may require two or more seasons before
+its external characteristics are fully developed. Immature males do
+not differ externally from the old female. The male secondary sexual
+characters consist principally in the prolongation of some of the
+fin-rays, or of entire fins; and in <i>Salmonidæ</i> in the greater
+development of the jaw-bones. The coloration of the male is in many
+fishes much brighter and more variegated than that of the female,
+but in comparatively<span class="pagenum" id="Page_177">[177]</span> few permanent (as in some <i>Callionymus</i>,
+<i>Labrus mixtus</i>); generally it is acquired immediately before and
+during the season of propagation only, and lost afterwards. Another
+periodical change in the integuments, also due to sexual influence and
+peculiar to the male, is the excrescence of wart-like tubercles on the
+skin of many <i>Cyprinoids</i>; they are developed chiefly on the head,
+but sometimes extend over the whole body and all the fins.</p>
+
+<p>With regard to size, it appears that in all Teleosteous fishes the
+female is larger than the male; in many Cyprinodonts the male may be
+only one-sixth or even less of the bulk of the female. The observations
+on the relative size of the sexes are few in Palæichthyes, but such
+as have been made tend to show that, if a difference exists at all,
+the male is generally the larger (<i>Lepidosteus</i>). In the Rays
+(<i>Raja</i>) the sexes, after they have attained maturity, differ in
+the development of dermal spines and the form of the teeth, the female
+being frequently much rougher than the male. There is much variation
+in this respect in the different species; but the males are constantly
+distinguished by an oblong patch of erectile claw-like spines on each
+pectoral fin, and by having the teeth (all, or only a portion) pointed,
+and not obtuse, like those of the females. In Sharks no secondary
+sexual differences have been observed; the male <i>Chimæridæ</i> (see
+Fig. <a href="#fig96">96</a>, p. 184), possess a singular comb-like cartilaginous appendage
+on the top of the head, which can be erected or depressed into a
+groove, both the appendage and the anterior part of the groove being
+armed with hooklets. The use of this singular organ is not known.</p>
+
+<p>The majority of Teleostei are <i>mixogamous</i>—that is, the males and
+females congregate on the spawning-beds, and the number of the former
+being in excess, several males attend to the same female, frequently
+changing from one female to another. The same habit has been observed
+in<span class="pagenum" id="Page_178">[178]</span> <i>Lepidosteus</i>. <i>Gastrosteus</i> is truly polygamous,
+several females depositing their ova into the same nest, guarded by
+one male only. Some Teleostei (<i>Ophiocephalus</i>), and probably
+all Chondropterygians, are monogamous; and it is asserted that the
+connection between the pair is not merely temporary, but lasts until
+they are separated by accident. Monogamous are probably also all those
+Teleosteans which bring forth living young, and those, the males of
+which, for the attraction of the female, are provided with appendages,
+or ornamented with a bright coloration.</p>
+
+<p><i>Hybridism</i> is another source of changes and variations within the
+limits of a species, and is by no means so scarce as has been believed
+hitherto; it is only apparently of exceptional occurrence, because
+the life of fishes is more withdrawn from our direct observation
+than that of terrestrial animals. It has been observed among
+species of <i>Serranus</i>, <i>Pleuronectidæ</i>, <i>Cyprinidæ</i>,
+<i>Clupeidæ</i>, and especially <i>Salmonidæ</i>. As in other animals,
+the more certain kinds of fishes are brought under domestication,
+the more readily do they interbreed with other allied species. It is
+characteristic of hybrids that their characters are very variable,
+the degrees of affinity to one or the other of the parents being
+inconstant; and as these hybrids are known readily to breed with either
+of the parent race, the variations of form, structure, and colour
+are infinite. Of internal organs the dentition, gill-rakers, pyloric
+appendages, are those particularly affected by such mixture of species.</p>
+
+<hr class="tb">
+
+<p>Some fishes are known to grow rapidly (in the course of from one to
+three years) and regularly to a certain size, growth being definitely
+arrested after the standard has been attained. Such fishes may be
+called “full-grown,” in the sense in which the term is applied to
+warm-blooded Vertebrates—the Sticklebacks, most Cyprinodonts, and many
+Clupeoids (Herring,<span class="pagenum" id="Page_179">[179]</span> Sprat, Pilchard) are examples of this regular
+kind of growth.<a id="FNanchor_15" href="#Footnote_15" class="fnanchor">[15]</a> But in the majority of fishes the rate of growth
+is extremely irregular, and it is hardly possible to know when growth
+is actually and definitely arrested. All seems to depend on the amount
+of food and the more or less favourable circumstances under which the
+individual grows up. Fishes which rapidly grow to a definite size are
+short-lived, whilst those which steadily and slowly increase in size
+attain to a great age, Teleosteans as well as Chondropterygians. Carp
+and Pike have been ascertained to live beyond a hundred years.</p>
+
+<p>It is evident that such diversity and irregularity of growth in
+the same species is accompanied by considerable differences in the
+appearance and general development of the fish. No instance is more
+remarkable than that of the so-called <i>Leptocephali</i>, which for a
+long time have been regarded either as a distinct group of Fishes, or
+as the larval stages of various genera of fishes.</p>
+
+  <div class="figcenter" id="fig95" style="max-width: 498px">
+     <img
+    class="p1"   
+    src="images/fig95.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 95.—Leptocephalus.</p>
+  </div>
+
+<p>The <i>Leptocephali</i> proper are small, narrow, elongate, more or
+less band-shaped fishes, pellucid in a fresh state, but assuming<span class="pagenum" id="Page_180">[180]</span> a
+white colour when preserved in spirits, resembling a tapeworm, being
+quite as soft and flexible. The skeleton is entirely cartilaginous, or
+slight ossifications are only now and then visible, especially towards
+the end of the vertebral column. The latter is replaced by a chorda
+dorsalis which, in many specimens, is found to be divided into numerous
+segments. Neural arches are sometimes present in their rudimentary
+condition. The anterior end of the chorda passes into the cartilaginous
+base of the skull, the connection not being by means of joint and
+ligaments. Hæmal arches are found on the caudal portion. Ribs none. The
+skull, like the vertebral column, is nearly entirely cartilaginous.
+The basisphenoid, frontal, and jaw-bones are the first which may be
+distinguished, and the mandible has generally ossifications.</p>
+
+<p>The muscles are generally not attached to the chorda, which is
+surrounded by a thick gelatinous mass, separating the lateral sets of
+muscles from each other. These muscles are attached to the external
+integument, each forming a thin flat angular band, the angle being
+directed forwards. However, specimens are frequently found in which the
+muscles are more developed, evidently at the expense of the gelatinous
+matter, which is diminished in quantity. They are attached to the
+chorda, and the entire fish has a more cylindrical form of the body
+(<i>Helmichthys</i>).</p>
+
+<p>The nervous, circulatory, and respiratory organs are well developed.
+In those with a sub-cylindrical body the blood is red, in those with
+a flat body the blood-corpuscles show but rarely a faint coloration.
+There are four branchial arches, and in some (<i>Tilurus</i>)
+pseudobrauchiæ have been found. The gill-openings are more or less
+narrow. The nostrils are double on each side, and the posterior is
+close to the eye.</p>
+
+<p>The stomach has a large blind sac, and in <i>Leptocephalus</i><span class="pagenum" id="Page_181">[181]</span> two
+lateral cæca. The intestine is straight, running close to the abdominal
+profile, with a small appendix directed forward and a larger one
+directed backwards. The vent is nearly always very small, and, in
+preserved examples at least, cannot always be discovered. Its position
+is variable, even in examples entirely similar in other points.
+Air-bladder none. No trace of generative organs.</p>
+
+<p>The vertical fins, when present, are confluent, with more or less
+conspicuous traces of rays; sometimes they are merely a fold of the
+skin, without any rays. Pectoral fins sometimes present, sometimes
+rudimentary, sometimes entirely absent. Ventrals none.</p>
+
+<p>Most examples have series of round black dots along each side of
+the abdominal profile, along the lateral line, and sometimes along
+the dorsal fin. They remind us of the luminous organs of many
+<i>Scopelidæ</i>, <i>Stomiatidæ</i>, and other pelagic fishes, but are
+composed entirely of pigmentary cells.</p>
+
+<p>These fishes are found floating in the sea, frequently at a great
+distance from land. Their movements are slow and languid. The largest
+specimen of Leptocephalus observed was 10 inches, but specimens of that
+size are very rare.</p>
+
+<div class="blockquot">
+
+<p>[See Kölliker, Zeitschr. wiss. Zool. iv. 1852, p. 360; and
+Carus, Ueber die Leptocephaliden. Leipz. 1861. 4to.]</p>
+</div>
+
+<p>Taking into account all the various facts mentioned, we must come to
+the conclusion that the Leptocephalids are the offspring of various
+kinds of marine fishes, representing, not a normal stage of development
+(larvæ), but an arrest of development at a very early period of their
+life; they continue to grow to a certain size without corresponding
+development of their internal organs, and perish without having
+attained the characters of the perfect animal. The cause by which this
+abnormal condition is brought about is not known; but it is quite
+within the limits of probability that fishes usually spawning in the
+vicinity of land sometimes<span class="pagenum" id="Page_182">[182]</span> spawn in the open ocean, or that floating
+spawn is carried by currents to a great distance from land; and that
+such embryoes, which for their normal growth require the conditions
+afforded by the vicinity of the shore, if hatched in mid-ocean, grow
+into undeveloped hydropic creatures, such as the Leptocephales seem to
+be.</p>
+
+<hr class="tb">
+
+<p>Abundance or scarcity of food, and other circumstances connected
+with the localities inhabited by fishes, affect considerably the
+colour of their muscles and integuments; the periodical changes of
+colour in connection with their sexual functions have been referred
+to above (p. 176). The flesh of many Teleostei is colourless, or but
+slightly tinged by the blood; that of Scombridæ, most Ganoids and
+Chondropterygians, is more or less red; but in badly-fed fishes, as
+well as in very young ones, the flesh is invariably white (anæmic).
+Many fishes, like the <i>Salmonidæ</i>, feed at times exclusively on
+Crustaceans, and the colouring substance of these Invertebrates, which
+by boiling and by the stomachic secretion turns red, seems to pass
+into the flesh of the fishes, imparting to it the well-known “salmon”
+colour. Further, the coloration of the integuments of many marine
+fish is dependent on the nature of their surroundings. In those which
+habitually hide themselves on the bottom, in sand, between stones or
+seaweeds, the colours of the body readily assimilate to those of the
+vicinity, and are thus an important element in the economy of their
+life. The changes from one set or tinge of colours to another may be
+rapid and temporary, or more or less permanent; in some fishes—as
+in the Pediculati, of which the Sea-Devil, or <i>Lophius</i>, and
+<i>Antennarius</i> are members—scarcely two individuals are found
+exactly alike in coloration, and only too frequently such differences
+in coloration are mistaken for specific characters. The changes of
+colours are produced in two ways: either by an increase or decrease of
+the<span class="pagenum" id="Page_183">[183]</span> black, red, yellow, etc., pigment-cells, or <i>chromatophors</i>,
+in the skin of the fish; or by the rapid contraction or expansion of
+the chromatophors which happen to be developed. The former change
+is gradual, like every kind of growth or development; the latter
+rapid, owing to the great sensitiveness of the cells, but certainly
+involuntary. In many bright-shining fishes—as Mackerels, Mullets—the
+colours appear to be brightest in the time intervening between the
+capture of the fish and its death: a phenomenon clearly due to the
+pressure of the convulsively-contracted muscles on the chromatophors.
+External irritation readily excites the chromatophors to expand—a
+fact unconsciously utilised by fishermen, who, by scaling the Red
+Mullet immediately before its death, produce the desired intensity
+of the red colour of the skin, without which the fish would not be
+saleable. However, it does not require such strong measures to prove
+the sensitiveness of the chromatophors to external irritation, the mere
+change of darkness into light is sufficient to induce them to contract,
+the fish appearing paler, and <i>vice versa</i>. In Trout which are
+kept or live in dark places, the black chromatophors are expanded, and,
+consequently, such specimens are very dark-coloured; when removed to
+the light they become paler almost instantaneously.</p>
+
+<p>Total absence of chromatophors in the skin, or <i>Albinism</i>, is very
+rare among fishes; much more common is <i>incipient Albinism</i>, in
+which the dark chromatophors are changed into cells with a more or less
+intense yellow pigment. Fishes in a state of domestication, like the
+Crucian Carp of China, the Carp, Tench, and the Ide, are particularly
+subject to this abnormal coloration, and are known as the common
+Gold-fish, the Gold-Tench, and the Gold-Orfe. But it occurs also not
+rarely in fishes living in a wild state, and has been observed in the
+Haddock, Flounder, Plaice, Carp, Roach, and Eel.</p>
+
+<p><span class="pagenum" id="Page_184">[184]</span></p>
+
+<p>It will be evident, from the foregoing remarks, that the amount of
+variation within the limits of the same species—either due to the
+natural growth and development, or to external physical conditions,
+or to abnormal accidental circumstances—is greater in fishes than
+in any of the higher classes of Vertebrates. The amount of variation
+is greater in certain genera or families than in others, and it is
+much greater in Teleosteans and Ganoids than in Chondropterygians.
+Naturally, it is greatest in the few species which have been
+domesticated, and which we shall mention in the succeeding chapter.</p>
+
+  <div class="figcenter" id="fig96" style="max-width: 400px">
+     <img
+    class="p1"   
+    src="images/fig96.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 96.—Chimæra colliei ♂, west coast of
+North America. A. Front view of head. B. Palate. <i>a</i>, Peritoneal
+aperture; <i>b</i>, Nostrils; <i>c</i>, Vomerine teeth; <i>d</i>,
+Mandibular teeth; <i>e</i>, Palatine teeth; <i>f</i>, Claspers.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_185">[185]</span></p>
+
+<h2 class="smaller">CHAPTER XIV.<br>
+<span class="subhed">DOMESTICATED AND ACCLIMATISED FISHES; ARTIFICIAL IMPREGNATION
+OF OVA—TENACITY OF LIFE AND REPRODUCTION OF LOST
+PARTS—HYBERNATION—USEFUL AND POISONOUS FISHES.</span></h2></div>
+
+<p>A few fishes only are thoroughly domesticated—that is, bred in
+captivity, and capable of transportation within certain climatic
+limits—viz. the Carp, Crucian Carp (European and Chinese varieties),
+Tench, Orfe or Ide, and the Goramy. The two former have accompanied
+civilised man almost to every place of the globe where he has effected
+a permanent settlement.</p>
+
+<p>Attempts to acclimatise particularly useful species in countries in
+which they were not indigenous have been made from time to time, but
+were permanently successful in a few instances only; the failures
+being due partly to the choice of a species which did not yield the
+profitable return expected, partly to the utter disregard of the
+difference of the climatic and other physical conditions between the
+original and new homes of the fish. The first successful attempts of
+acclimatisation were made with domestic species, viz. the Carp and
+Gold-fish, which were transferred from Eastern Asia to Europe. Then,
+in the first third of the present century, the Javanese Goramy was
+acclimatised in Mauritius and Guiana, but no care seems to have been
+taken to insure permanent advantages from the successful execution
+of the experiment. In these cases fully developed individuals were
+transported to<span class="pagenum" id="Page_186">[186]</span> the country in which they were to be acclimatised. The
+most successful attempt of recent years is the acclimatisation of the
+Trout and Sea-Trout, and probably also of the Salmon, in Tasmania and
+New Zealand, and of the Californian Salmon (<i>Salmo quinnat</i>?),
+in Victoria, by means of artificially-impregnated ova. The ova were
+transported on ice, in order to retard their development generally,
+and thus to preserve them from destruction during the passage of the
+tropical zone.</p>
+
+<p><i>Artificial impregnation</i> of fish-ova was first practised by
+<span class="smcap">J. L. Jacobi</span>, a native of Westphalia, in the years 1757–63,
+who employed exactly the same method which is followed now; and there
+is no doubt that this able observer of nature conceived and carried
+out his idea with the distinct object of advantageously restocking
+water-courses which had become unproductive, and increasing production
+by fecundating and preserving all ova, of which a great proportion,
+in the ordinary course of propagation, would be left unfecundated
+or accidentally perish. Physiology soon turned to account Jacobi’s
+discovery, and artificial impregnation has proved to be one of the
+greatest helps to the student of embryology.</p>
+
+<p>Fishes differ in an extraordinary degree with regard to tenacity of
+life. Some will bear suspension of respiration—caused by removal from
+water, or by exposure to cold or heat—for a long time, whilst others
+succumb at once. Nearly all marine fishes are very sensitive to changes
+in the temperature of the water, and will not bear transportation from
+one climate to another. This seems to be much less the case with some
+freshwater fishes of the temperate zones: the Carp may survive after
+being frozen in a solid block of ice, and will thrive in the southern
+parts of the temperate zone. On the other hand, some freshwater
+fishes are so sensitive to a change in the water that they perish
+when transplanted from their native river into another apparently
+offering the<span class="pagenum" id="Page_187">[187]</span> same physical conditions (Grayling, <i>Salmo hucho</i>).
+Some marine fishes may be abruptly transferred from salt into fresh
+water, like Sticklebacks, some Blennies, and <i>Cottus</i>, etc.;
+others survive the change when gradually effected, as many migratory
+fishes; whilst again, others cannot bear the least alteration in the
+composition of the salt water (all pelagic fishes). On the whole,
+instances of marine fishes voluntarily entering brackish or fresh water
+are very numerous, whilst freshwater fishes proper but rarely descend
+into salt water.</p>
+
+<p>Abstinence from food affects different fishes in a similarly different
+degree. Marine fishes can endure hunger less than freshwater fishes,
+at least in the temperate zones, no observations having been made in
+this respect on tropical fishes. Goldfishes, Carps, Eels, are known to
+be able to subsist without food for months, without showing a visible
+decrease of bulk; whilst the Trigloids, Sparoids, and other marine
+fishes, survive abstinence from food for a few days only. In freshwater
+fishes the temperature of the water is of great influence on their
+vital functions generally, and consequently on their appetite,—many
+cease to feed altogether in the course of the winter; a few, like the
+Pike, are less inclined to feed during the heat of the summer than when
+the temperature is lowered.</p>
+
+<p>Captivity is easily borne by most fishes, and the appliances introduced
+in our modern aquaria have rendered it possible to keep in confinement,
+and even to induce to propagate, fishes which formerly were considered
+to be intolerant of captivity.</p>
+
+<p>Wounds affect fishes generally much less than higher Vertebrates. A
+Greenland Shark continues to feed whilst his head is pierced by a
+harpoon or by the knife, as long as the nervous centre is not touched;
+a Sea-perch or a Pike (Fig. <a href="#fig97">97</a>) will survive the loss of a portion of
+its tail; a Carp that of half of its snout. However, some fishes are
+much more<span class="pagenum" id="Page_188">[188]</span> sensitive, and perish even from the superficial abrasion
+caused by the meshes of the net during capture (<i>Mullsn</i>.)</p>
+
+<p>The power of <i>reproduction</i> of <i>lost parts</i> in Teleosteous
+fishes is limited to the delicate terminations of their fin-rays
+and the various tegumentary filaments with which some are provided.
+These filaments are sometimes developed in an extraordinary degree,
+mimicking the waving fronds of the seaweed in which the fish hides.
+Both the ends of the fin-rays and the filaments are frequently lost,
+not only by accident, but merely by wear and tear; and as these organs
+are essential for the preservation of the fish, their reproduction is
+necessary.</p>
+
+  <div class="figcenter" id="fig97" style="max-width: 541px">
+     <img
+    class="p1"   
+    src="images/fig97.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 97.—Pike caught in the Thames, which, when young,
+had lost part of the tail with the caudal fin.</p>
+  </div>
+
+<p>In Dipnoi, <i>Ceratodus</i>, and <i>Protopterus</i>, the terminal
+portion of the tail has been found to have been reproduced, but without
+the notochord.</p>
+
+<hr class="tb">
+
+<p><i>Hybernation</i> has been observed in many Cyprinoids and Murænoids
+of the temperate zones. They do not fall into a condition of complete
+torpidity, as Reptiles and Mammals, but their vital functions are
+simply lowered, and they hide in sheltered holes, and cease to go
+abroad in search of their food. Between the tropics a great number
+of fishes (especially Siluroids, Labyrinthici, Ophiocephaloids, the
+Dipnoi), are known to survive long-continued droughts by passing the
+dry season in a perfectly torpid state, imbedded in the hardened mud.
+Protopterus, and probably many of the other fishes mentioned, prepare
+for themselves a cavity large enough to hold them, and coated on the
+inside with a layer of hardened mucus, which preserves them from
+complete desiccation.<span class="pagenum" id="Page_189">[189]</span> It has been stated that in India fishes may
+survive in this condition for more than one season, and that ponds
+known to have been dry for several years, and to the depth of many
+feet, have swarmed with fishes as soon as the accumulation of water
+released them from their hardened bed.</p>
+
+<hr class="tb">
+
+<p>The principal <i>use</i> derived by man from the class of Fishes
+consists in the abundance of wholesome and nourishing food which they
+yield. In the Polar regions especially, whole tribes are entirely
+dependent on this class for subsistence; and in almost all nations
+fishes form a more or less essential part of food, many being, in a
+preserved condition, most important articles of trade. The use derived
+by man from them in other respects is of but secondary importance.
+Cod-liver oil is prepared from the liver of some of the Gadoids of the
+Northern Hemisphere, and of Sharks; isinglass from the swim-bladder of
+Sturgeons, Sciænoids, and Polynemoids; shagreen from the skin of Sharks
+and Rays.</p>
+
+<hr class="tb">
+
+<p>The flesh of some fishes is at times, or constantly, <i>poisonous</i>.
+When eaten, it causes symptoms of more or less intense irritation of
+the stomach and intestines, inflammation of the mucous membranes,
+and not rarely death. The fishes, the flesh of which appears always
+to have poisonous properties, are <i>Clupea thrissa</i>, <i>Clupea
+venenosa</i>, and some species of <i>Scarus</i>, <i>Tetrodon</i>,
+and <i>Diodon</i>. There are many others which have occasionally or
+frequently caused symptoms of poisoning. Poey enumerates not less
+than seventy-two different kinds from Cuba; and various species of
+<i>Sphyræna</i>, <i>Balistes</i>, <i>Ostracion</i>, <i>Caranx</i>,
+<i>Lachnolæmus</i>, <i>Tetragonurus</i>, <i>Thynnus</i>, have been
+found to be poisonous in all seas between the tropics. All or nearly
+all these fishes acquire their poisonous properties from their food
+which consists of poisonous Medusæ, Corals, or decomposing substances.
+Frequently the fishes<span class="pagenum" id="Page_190">[190]</span> are found to be eatable if the head and
+intestines be removed immediately after capture. In the West Indies it
+has been ascertained that all the fishes living and feeding on certain
+coral banks are poisonous. In other fishes the poisonous properties are
+developed at certain seasons of the year only, especially the season of
+propagation: as the Barbel, Pike, and Burbot, whose roe causes violent
+diarrhœas when eaten during the season of spawning.</p>
+
+  <div class="figcenter" id="fig98" style="max-width: 335px">
+     <img
+    class="p1"   
+    src="images/fig98.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 98.—Portion of tail, with spines, of <i>Aëtobatis
+narinari</i>, a Sting-ray from the Indian Ocean. <i>a</i>, nat. size.</p>
+  </div>
+
+<hr class="tb">
+
+<p><i>Poison-organs</i> are more common in the class of Fishes than was
+formerly believed, but they seem to have exclusively the function
+of defence, and are not auxiliary in procuring food, as in venomous
+Snakes. Such organs are found in the Sting-rays, the tail of which is
+armed with one or more powerful barbed spines. Although they lack a
+special organ secreting poison, or a canal in or on the spine by which
+the venomous fluid is conducted, the symptoms caused by a wound from
+the spine of a Sting-ray are such as cannot be accounted for merely by
+the mechanical laceration, the pain being intense, and the subsequent
+inflammation and swelling of the wounded part terminating not rarely
+in gangrene. The mucus secreted from the surface of the fish and
+inoculated by the jagged spine evidently possesses venomous properties.
+This is also the case in many Scorpænoids, and in the Weaver
+(<i>Trachinis</i>), in which the dorsal and opercular spines have the
+same<span class="pagenum" id="Page_191">[191]</span> function as the caudal spines of the Sting-rays; however, in the
+Weavers the spines are deeply grooved, the groove being charged with a
+fluid mucus. In <i>Synanceia</i> the poison-organ (Fig. <a href="#fig99">99</a>,) is still
+more developed: each dorsal spine is in its terminal half provided
+with a deep groove on each side, at the lower end of which lies a
+pear-shaped bag containing the milky poison; it is prolonged into a
+membranous duct, lying in the groove of the spine, and open at its
+point. The native fishermen, well acquainted with the dangerous nature
+of these fishes, carefully avoid handling them; but it often happens
+that persons wading with naked feet in the sea, step upon the fish,
+which generally lies hidden in the sand. One or more of the erected
+spines penetrate the skin, and the poison is injected into the wound by
+the pressure of the foot on the poison-bags. Death has not rarely been
+the result.</p>
+
+  <div class="figcenter" id="fig99" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig99.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 99.—A dorsal spine, with poison-bags, of
+<i>Synanceia verrucosa</i>. Indian Ocean.</p>
+  </div>
+
+  <div class="figcenter" id="fig100" style="max-width: 267px">
+     <img
+    class="p1"   
+    src="images/fig100.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 100.—Opercular part of the Poison-apparatus of
+<i>Thalassophryne</i> (Panama).</p>
+     <p class="p0 p-left hangingindent smaller">1. Hinder half of the head, with the venom-sac* <i>in situ.</i>
+<i>a</i>, Lateral line and its branches; <i>b</i>, Gill-opening;
+<i>c</i>, Ventral fin; <i>d</i>, Base of Pectoral fin; <i>e</i>, Base
+of dorsal.</p>
+     <p class="p0 center smaller">2. Operculum with the perforated spine.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_192">[192]</span></p>
+
+<p>The most perfect poison-organs hitherto discovered in fishes are
+those of <i>Thalassophryne</i>, a Batrachoid genus of fishes from the
+coasts of Central America. In these fishes the operculum again and the
+two dorsal spines are the weapons. The former (Fig. <a href="#fig100">100</a>, <sup>2</sup>) is very
+narrow, vertically styliform and very mobile; it is armed behind with a
+spine, eight lines long, and of the same form as the hollow venom-fang
+of a snake, being perforated at its base and at its extremity. A sac
+covering the base of the spine discharges its contents through the
+apertures and the canal in the interior of the spine. The structure of
+the dorsal spines is similar. There are no secretory glands imbedded
+in the membranes of the sacs; and the fluid must be secreted by their
+mucous membrane. The sacs are without an external muscular layer, and
+situated immediately below the thick loose skin which envelops the
+spines to their extremity; the ejection of the poison into a living
+animal, therefore, can only be effected, as in <i>Synanceia</i>, by
+the pressure to which the sac is subjected the moment the spine enters
+another body.</p>
+
+<p>Finally, a singular apparatus found in many Siluroids may be mentioned
+in connection with the poison-organs, although its function is still
+problematical. Some of these fishes are armed with powerful pectoral
+spines and justly feared on account of the dangerous wounds they
+inflict; not a few of them possess, in addition to the pectoral spines,
+a sac with a more or less wide opening in the axil of the pectoral fin;
+and it does not seem improbable that it contains a fluid which may be
+introduced into a wound by means of the pectoral spine, which would
+be covered with it, like the barbed arrow-head of an Indian. However,
+whether this secretion is equally poisonous in all the species provided
+with that axillary sac, or whether it has poisonous qualities at all,
+is a question which can be decided by experiments only made with the
+living fishes.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_193">[193]</span></p>
+
+<h2 class="smaller">CHAPTER XV.<br>
+<span class="subhed">DISTRIBUTION OF FISHES IN TIME.</span></h2></div>
+
+<p>Of what kind the fishes were which were the first to make their
+appearance on the globe; whether or not they were identical with,
+or similar to, any of the principal types existing at present; are
+questions which probably will for ever remain hidden in mystery and
+uncertainty. The supposition that the Leptocardii and Cyclostomes,
+the lowest of the vertebrate series, must have preceded the other
+sub-classes, is an idea which has been held by many Zoologists: and
+as the horny teeth of the Cyclostomes are the only parts of their
+body which under favourable circumstances might have been preserved,
+Palæontologists have ever been searching for this evidence.</p>
+
+  <div class="figcenter" id="fig101" style="max-width: 150px">
+     <img
+    class="p1"   
+    src="images/fig101.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 101. Right dental plate of Myxine affinis.</p>
+  </div>
+
+<p>Indeed, in deposits belonging to the Lower Silurian and Devonian, in
+Russia, England, and North America, minute, slender, pointed horny
+bodies, bent like a hook, with sharp opposite margins, have been found
+and described under the name of <i>Conodonts</i>. More frequently they
+possess an elongated basal portion, in which there is generally a
+larger tooth with rows of similar but smaller denticles on one or both
+sides of the larger tooth, according as this is central or at one end
+of the base. In other examples there is no prominent central tooth,
+but a series of more or less similar teeth is implanted on a straight
+or curved base. Modifications of these arrangements are very numerous,
+and many Palæontologists entertain still doubts whether the origin
+of these<span class="pagenum" id="Page_194">[194]</span> remains is not rather from Annelids and Mollusks than from
+Fishes.</p>
+
+<div class="blockquot">
+
+<p>[See G. J. Hinde, in “Quarterly Journal of the Geological
+Society,” 1879.]</p>
+</div>
+
+<p>The first undeniable evidence of a fish, or, indeed, of a vertebrate
+animal, occurs in the <i>Upper Silurian</i> Rocks, in a bone-bed
+of the Downton sandstone, near Ludlow. It consists of compressed,
+slightly curved, ribbed spines, of less than two inches in length
+(<i>Onchus</i>); of small shagreen-scales (<i>Thelodus</i>); the
+fragment of a jaw-like bar with pluricuspid teeth (<i>Plectrodus</i>);
+the cephalic bucklers of what seems to be a species of
+<i>Pteraspis</i>; and, finally, the coprolitic bodies of phosphate and
+carbonate of lime, including recognisable remains of the Mollusks and
+Crinoids inhabiting the same waters. But no vertebra or other part
+of the skeleton has been found. The spines and scales seem to have
+belonged to the same kind of fish, which probably was a Plagiostome.
+It is quite uncertain whether or not the jaw (if it be the jaw of
+a fish<a id="FNanchor_16" href="#Footnote_16" class="fnanchor">[16]</a>) belonged to the buckler-bearing <i>Pteraspis</i>, the
+position of which among Ganoids, with which it is generally associated,
+is open to doubt.</p>
+
+<p>No detached undoubted tooth of a Plagiostome or Ganoid scale has been
+discovered in the Ludlow deposits: but so much is certain that those
+earliest remains in Palæozoic rocks belonged to fishes closely allied
+to forms occurring in greater abundance in the succeeding formation,
+the Devonian, where they are associated with undoubted Palæichthyes,
+Plagiostomes as well as Ganoids.</p>
+
+<hr class="tb">
+
+<p>These fish-remains of the <i>Devonian</i> or <i>Old Red Sandstone</i>,
+can be determined with greater certainty. They consist of spines
+or the so-called <i>Ichthyodorulites</i>, which show sufficiently
+distinctive characters to be referred to several genera, one of<span class="pagenum" id="Page_195">[195]</span> them,
+<i>Onchus</i>, still surviving from the Silurian epoch. All these
+spines are believed to be those of Chondropterygians, to which order
+some pluricuspid teeth (<i>Cladodus</i>) from the Old Red Sandstone in
+the vicinity of St. Petersburg have been referred likewise.</p>
+
+<p>The remains of the Ganoid fishes are in a much more perfect state of
+preservation, so that it is even possible to obtain a tolerably certain
+idea of the general appearance and habits of some of them, especially
+of such as were provided with hard carapaces, solid scales, and
+ordinary or bony fin-rays. A certain proportion of them, as might have
+been expected, remind us, with regard to external form, of Teleosteous
+fishes rather than of any of the few still existing Ganoid types; but
+it is contrary to all analogy and to all palæontological evidence
+to suppose that those fishes were, with regard to their internal
+structure, more nearly allied to Teleosteans than to Ganoids. If they
+were not true Ganoids, they may be justly supposed to have had the
+essential characters of Palæichthyes. Other forms exhibit even at that
+remote geological epoch so unmistakably the characteristics of existing
+Ganoids, that no one can entertain any doubt with regard to their place
+in the system. In none of these fishes is there any trace of vertebral
+segmentation.</p>
+
+<p>The Palæichthyes of the Old Red Sandstone, the systematic position of
+which is still obscure, are the <i>Cephalaspidæ</i> from the Lower Old
+Red Sandstone of Great Britain and Eastern Canada; <i>Pterichthys</i>,
+<i>Coccosteus</i>, and <i>Dinichthys</i>: genera which have been
+combined in one group—<i>Placodermi</i>; and <i>Acanthodes</i>
+and allied genera, which combined numerous branchiostegals with
+chondropterygian spines and a shagreen-like dermal covering.</p>
+
+<p>Among the other Devonian fishes (and they formed the majority) two
+types may be recognised, both of which are unmistakably Ganoids. The
+first approaches the still living<span class="pagenum" id="Page_196">[196]</span> <i>Polypterus</i>, with which
+some of the genera like <i>Diplopterus</i> singularly agree in the
+form and armature of the head, the lepidosis of the body, the lobate
+pectoral fins, and the termination of the vertebral column. Other
+genera, as <i>Holoptychius</i>, have cycloid scales; many have two
+dorsal fins (<i>Holoptychius</i>), and, instead of branchiostegals,
+jugular scutes; others one long dorsal confluent with the caudal
+(<i>Phaneropleuron</i>).</p>
+
+<p>In the second type the principal characters of the <i>Dipnoi</i>
+are manifest, and some of them, for example <i>Dipterus</i>,
+<i>Palædaphus</i>, <i>Holodus</i>, approach so closely the Dipnoi which
+still survive, that the differences existing between them warrant a
+separation into families only.</p>
+
+<p>Devonian fishes are frequently found under peculiar circumstances,
+enclosed in the so-called <i>nodules</i>. These bodies are elliptical
+flattened pebbles, which have resisted the action of water in
+consequence of their greater hardness, whilst the surrounding rock has
+been reduced to detritus by that agency. Their greater density is due
+to the dispersion in their substance of the fat of the animal which
+decomposed in them. Frequently, on cleaving one of these nodules with
+the stroke of the hammer, a fish is found embedded in the centre. At
+certain localities of the Devonian, fossil fishes are so abundant
+that the whole of the stratum is affected by the decomposing remains
+emitting a peculiar smell when newly opened, and acquiring a density
+and durability not possessed by strata without fishes. The flagstones
+of Caithness are a remarkable instance of this.</p>
+
+<hr class="tb">
+
+<p>The fish-remains of the <i>Carboniferous</i> formation show a great
+similarity to those of the preceding. They occur throughout the series,
+but are very irregularly distributed, being extremely scarce in some
+countries, whilst in others entire beds (the so-called bone-beds) are
+composed of ichthyolites.<span class="pagenum" id="Page_197">[197]</span> In the ironstones they frequently form the
+nuclei of nodules, as in the Devonian.</p>
+
+<p>Of Chondropterygians the spines of <i>Onchus</i> and others still
+occur, with the addition of teeth indicative of the existence of fishes
+allied to the Cestracion-type (<i>Cochliodus</i>, <i>Psammodus</i>): a
+type which henceforth plays an important part in the composition of the
+extinct marine fish faunæ. Another extinct Selachian family, that of
+Hybodontes, makes its appearance, but is known from the teeth only.</p>
+
+<p>Of the Ganoid fishes, the family <i>Palæoniscidæ</i> (Traquair) is
+numerously represented; others are Cœlacanths (<i>Cœlocanthus</i>,
+<i>Rhizodus</i>), and <i>Saurodipteridæ</i> (<i>Megalichthys</i>).
+None of these fishes have an ossified vertebral column, but in some
+(<i>Megalichthys</i>) the outer surface of the vertebræ is ossified
+into a ring; the termination of their tail is heterocercal. The
+carboniferous <i>Uronemus</i> and the Devonian <i>Phaneropleuron</i>
+are probably generically the same; and the Devonian <i>Dipnoi</i> are
+continued as, and well represented by, <i>Ctenodus</i>.</p>
+
+<hr class="tb">
+
+<p>The fishes of the <i>Permian</i> group are very similar to those of
+the Carboniferous. A type which in the latter was but very scantily
+represented, namely the <i>Platysomidæ</i>, is much developed. They
+were deep-bodied fish, covered with hard rhomboid scales possessing
+a strong anterior rib, and provided with a heterocercal caudal, long
+dorsal and anal, short non-lobate paired fins (when present), and
+branchiostegals. The <i>Palæoniscidæ</i> are represented by many
+species of <i>Palæoniscus</i>, <i>Pygopterus</i> and <i>Acrolepis</i>,
+and Cestracionts by <i>Janassa</i> and <i>Strophodus</i>.</p>
+
+<hr class="tb">
+
+<p>The passage from the Palæozoic into the <i>Mesozoic</i> era is not
+indicated by any marked change as far as fishes are concerned. The
+more remarkable forms of the Trias are Shark-like fishes represented
+by ichthyodorulithes like <i>Nemacanthus</i>, <i>Liacanthus</i>,
+and <i>Hybodus</i>; and Cestracionts represented by<span class="pagenum" id="Page_198">[198]</span> species
+of <i>Acrodus</i> and <i>Strophodus</i>. Of the Ganoid genera
+<i>Cœlacanthus</i>, <i>Amblypterus</i> (<i>Palæoniscidæ</i>),
+<i>Saurichthys</i> persist from the Carboniferous epoch.
+<i>Ceratodus</i> appears for the first time (Muschel-Kalk of Germany).</p>
+
+<p>Thanks to the researches of Agassiz, and especially Sir P. Egerton,
+the ichthyological fauna of the Lias is, perhaps, the best known
+of the Mesozoic era, 152 species having been described. Of the
+various localities, Lyme Regis has yielded more than any other,
+nearly all the Liassic genera being represented there by not less
+than seventy-nine species. The Hybodonts and Cestracionts continue
+in their fullest development. Holocephales (<i>Ischyodus</i>),
+true Sharks (<i>Palæoscyllium</i>), Rays (<i>Squaloraja</i>,
+<i>Arthropterus</i>), and Sturgeons (<i>Chondrosteus</i>) make
+their first appearance; but they are sufficiently distinct from
+living types to be classed in separate genera, or even families. The
+Ganoids, especially Lepidosteoids, predominate over all the other
+fishes: <i>Lepidotus</i>, <i>Semionotus</i>, <i>Pholidophorus</i>,
+<i>Pachycormus</i>, <i>Eugnathus</i>, <i>Tetragonolepis</i>, are
+represented by numerous species; other remarkable genera are
+<i>Aspidorhynchus</i>, <i>Belonostomus</i>, <i>Saurostomus</i>,
+<i>Sauropsis</i>, <i>Thrissonotus</i>, <i>Conodus</i>,
+<i>Ptycholepis</i>, <i>Endactis</i>, <i>Centrolepis</i>,
+<i>Legnonotus</i>, <i>Oxygnathus</i>, <i>Heterolepidotus</i>,
+<i>Isocolum</i>, <i>Osteorhachis</i>, <i>Mesodon</i>. These genera
+offer evidence of a great change since the preceding period, the
+majority not being represented in older strata, whilst, on the other
+hand, many are continued into the succeeding oolithic formations. The
+homocercal termination of the vertebral column commences to supersede
+the heterocercal, and many of the genera have well ossified and
+distinctly segmented spinal columns. Also the cycloid form of scales
+becomes more common: one genus (<i>Leptolepis</i>) being, with regard
+to the preserved hard portions of its organisation, so similar to the
+Teleosteous type that some Palæontologists refer it (with much reason)
+to that sub-class.</p>
+
+<div class="blockquot">
+
+<p>[See <i>E. Sauvage</i>, Essai sur la Faune Ichthyologique de la
+période Liasique. In “Bibl. de l’école des hautes études,” xiii.
+art. 5. Paris 1875. 8<sup>o</sup>.]</p>
+</div>
+
+<p><span class="pagenum" id="Page_199">[199]</span></p>
+
+<p>As already mentioned, the <i>Oolithic</i> formations show a great
+similarity of their fish-fauna to that of the Lias; but still more
+apparent is its approach to the existing fauna. Teeth have been found
+which cannot even generically be distinguished from <i>Notidanus</i>.
+The Rays are represented by genera like <i>Spathobatis</i>,
+<i>Belemnobatis</i>, <i>Thaumas</i>; the <i>Holocephali</i> are
+more numerous than in the Lias (<i>Ischyodus</i>, <i>Ganodus</i>).
+The most common Ganoid genera are <i>Caturus</i>, <i>Pycnodus</i>,
+<i>Pholidophorus</i>, <i>Lepidotus</i>, <i>Leptolepis</i>, all of
+which had been more or less fully represented in the Lias. Also
+<i>Ceratodus</i> is continued into it.</p>
+
+<hr class="tb">
+
+<p>The <i>Cretaceous</i> group offers clear evidence of the further
+advance towards the existing fauna. Teeth of Sharks of existing genera
+<i>Carcharias</i> (<i>Corax</i>), <i>Scyllium</i>, <i>Notidanus</i>,
+and <i>Galeocerdo</i>, are common in some of the marine strata, whilst
+Hybodonts and Cestracionts are represented by a small number of
+species only; of the latter one new genus, <i>Ptychodus</i>, appears
+and disappears. A very characteristic Ganoid genus, <i>Macropoma</i>,
+comprises homocercal fishes with rounded ganoid scales sculptured
+externally and pierced by prominent mucous tubes. <i>Caturus</i>
+becomes extinct. Teeth and scales of <i>Lepidotus</i> (with
+<i>Sphærodus</i> as subgenus), clearly a freshwater fish, are widely
+distributed in the Wealden, and finally disappear in the chalk; its
+body was covered with large rhomboidal ganoid scales. <i>Gyrodus</i>
+and <i>Aspidorhynchus</i> occur in the beds of Voirons, <i>Coelodus</i>
+and <i>Amiopsis</i> (allied to Amra), in those of Comen, in Istria. But
+the Palæichthyes are now in the minority; undoubted Teleosteans have
+appeared, for the first time, on the stage of life in numerous genera,
+many of which are identical with still existing fishes. The majority
+are Acanthopterygians, but Physostomes and Plectognaths are likewise
+well represented, most of them being marine. Of Acanthopterygian
+families the first to appear are the <i>Berycidæ</i>,<span class="pagenum" id="Page_200">[200]</span> represented
+by several very distinct genera: <i>Beryx</i>; <i>Pseudoberyx</i>
+with abdominal ventral fins; <i>Berycopsis</i> with cycloid scales;
+<i>Homonotus</i>, <i>Stenostoma</i>, <i>Sphenocephalus</i>,
+<i>Acanus</i>, <i>Hoplopteryx</i>, <i>Platycornus</i> with
+granular scales; <i>Podocys</i> with a dorsal extending to the
+neck; <i>Acrogaster</i>, <i>Macrolepis</i>, <i>Rhacolepis</i>
+from the chalk of Brazil. The position of <i>Pycnosterynx</i> is
+uncertain, it approaches certain Pharyngognaths. True <i>Percidæ</i>
+are absent, whilst the <i>Carangidæ</i>, <i>Sphyrænidæ</i>,
+<i>Cataphracti</i>, <i>Gobiidæ</i>, <i>Cottidæ</i>, and <i>Sparidæ</i>
+are represented by one or more genera. Somewhat less diversified are
+the Physostomes, which belong principally to the <i>Clupeidæ</i>
+and <i>Dercetidæ</i>, most of the genera being extinct; Clupea is
+abundant in some localities. <i>Scopelidæ</i> (<i>Hemisaurida</i>
+and <i>Saurocephalus</i>) occur in the chalk of Comen in Istria, and
+of Mæstricht. Of all cretaceous deposits none surpass those of the
+Lebanon with regard to the number of genera, species, and individuals;
+the forms are exclusively marine, and the remains in the most perfect
+condition.</p>
+
+<hr class="tb">
+
+<p>In the <i>Tertiary</i> epoch the Teleosteans have almost entirely
+replaced the Ganoids; a few species only of the latter make their
+appearance, and they belong to existing genera, or, at least, very
+closely allied forms (<i>Lepidosteus</i>, <i>Amia</i>, <i>Hypamia</i>,
+<i>Acipenser</i>). The Chondropterygians merge more and more into
+recent forms; Holocephali continue, and still are better represented
+than in the present fauna. The Teleosteans show even in the Eocene a
+large proportion of existing genera, and the fauna of some localities
+of the Miocene (Oeningen) is almost wholly composed of them. On the
+whole, hitherto more than one-half have been found to belong to
+existing genera, and there is no doubt that the number of seemingly
+distinct extinct genera will be lessened as the fossils will be
+examined with a better knowledge of the living forms. The distribution
+of the fishes differed widely from<span class="pagenum" id="Page_201">[201]</span> that of our period, many of our
+tropical genera occurring in localities which are now included within
+our temperate zone, and being mixed with others, which nowadays are
+restricted to a colder climate: a mixture which continues throughout
+the Pliocene.</p>
+
+<hr class="tb">
+
+<p>A few families of fishes, like the freshwater Salmonidæ, seem to have
+put in their appearance in <i>Post-pliocene</i> times; however, not
+much attention has been paid to fish-remains of these deposits; and
+such as have been incidentally examined offer evidence of the fact that
+the distribution of fishes has not undergone any further essential
+change down to the present period.</p>
+
+<div class="blockquot">
+
+<p>[See <i>E. Sauvage</i>, Mémoire sur la Faune Ichthyologique de
+la période Tertiaire. Paris 1873. 8°.]</p>
+</div>
+
+  <div class="figcenter" id="fig102" style="max-width: 453px">
+     <img
+    class="p1"   
+    src="images/fig102.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 102.—<i>Pycnodus rhombus</i>, a Ganoid from the
+Upper Oolite.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_202">[202]</span></p>
+
+<h2 class="smaller">CHAPTER XVI.<br>
+<span class="subhed">THE DISTRIBUTION OF EXISTING FISHES OVER THE EARTH’S SURFACE—GENERAL
+REMARKS.</span></h2></div>
+
+<p>In an account of the geographical distribution of fishes the
+<i>Freshwater</i> forms are to be kept separate from the <i>Marine</i>.
+However, when we attempt to draw a line between these two kinds of
+fishes, we meet with a great number of species and of facts which would
+seem to render that distinction very vague. There are not only species
+which can gradually accommodate themselves to a sojourn in either salt
+or fresh water, but there are also such as seem to be quite indifferent
+to a rapid change from one into the other: so that individuals of
+one and the same species (Gastrosteus, Gobius, Blennius, Osmerus,
+Retropinna, Clupea, Syngnathus, etc.), may be found at some distance
+out at sea, whilst others live in rivers far beyond the influence of
+the tide, or even in inland fresh waters without outlet to the sea.
+The majority of these fishes belong to forms of the fauna of the
+<i>brackish</i> water, and as they are not an insignificant portion of
+the fauna of almost every coast, we shall have to treat of them in a
+separate chapter.</p>
+
+<p>Almost every large river offers instances of truly marine fishes
+(such as <i>Serranus</i>, <i>Sciænidæ</i>, <i>Pleuronectes</i>,
+<i>Clupeidæ</i>, <i>Tetrodon</i>, <i>Carcharias</i>, <i>Trygonidæ</i>),
+ascending for hundreds of miles of their course; and not periodically,
+or from any apparent physiological necessity, but sporadically
+throughout the year, just like the various kinds of marine
+Porpoises which are found all along the lower course of the Ganges,
+Yang-tseKiang,<span class="pagenum" id="Page_203">[203]</span> the Amazons, the Congo, etc. This is evidently the
+commencement of a change in a fish’s habits, and, indeed, not a few
+of such fishes have actually taken up their permanent residence in
+fresh waters (as species of Ambassis, Apogon Dules, Therapon, Sciæna,
+Blennius, Gobius, Atherina, Mugil, Myxus, Hemirhamphus, Clupea,
+Anguilla, Tetrodon, Trygon): all forms <i>originally marine</i>.</p>
+
+<p>On the other hand, we find fishes belonging to freshwater genera
+descending rivers and sojourning in the sea for a more or less limited
+period; but these instances are much less in number than those in
+which the reverse obtains. We may mention species of <i>Salmo</i> (the
+Common Trout, the Northern Charr), and Siluroids (as <i>Arius</i>,
+<i>Plotosus</i>). <i>Coregonus</i>, a genus so characteristic of the
+inland lakes of Europe, Northern Asia, and North America, nevertheless
+offers some instances of species wandering by the effluents into
+the sea, and taking up their residence in salt water, apparently
+by preference, as <i>Coregonus oxyrhynchus</i>. But of all the
+Freshwater families none exhibit so great a capability of surviving
+the change from fresh into salt water, as the <i>Gastrosteidæ</i>
+(Sticklebacks), of the northern Hemisphere, and the equally diminutive
+<i>Cyprinodontidæ</i> of the tropics; not only do they enter into,
+and live freely in, the sea, but many species of the latter family
+inhabit inland waters, which, not having an outlet, have become briny,
+or impregnated with a larger proportion of salts than pure sea water.
+During the voyage of the “Challenger” a species of <i>Fundulus</i>,
+<i>F. nigrofasciatus</i>, which inhabits the fresh and brackish waters
+of the Atlantic States of North America, was obtained, with Scopelids
+and other pelagic forms, in the tow-net, midway between St. Thomas and
+Teneriffe.</p>
+
+<p>Some fishes annually or periodically ascend rivers for the purpose of
+spawning, passing the rest of the year in the sea, as Sturgeons, many
+Salmonoids, some Clupeoids, Lampreys,<span class="pagenum" id="Page_204">[204]</span> etc. The two former evidently
+belonged originally to the freshwater series, and it was only in the
+course of their existence that they acquired the habit of descending
+to the sea, perhaps because their freshwater home did not offer a
+sufficient supply of food. These migrations of freshwater fishes have
+been compared with the migrations of birds; but they are much more
+limited in extent, and do not impart an additional element to the fauna
+of the place to which they migrate, as is the case with the distant
+countries to which birds migrate.</p>
+
+<p>The distinction between freshwater and marine fishes is further
+obscured by geological changes, in consequence of which the salt water
+is gradually being changed into fresh, or <i>vice versa</i>. These
+changes are so gradual and spread over so long a time, that many of
+the fishes inhabiting such localities accommodate themselves to the
+new conditions. One of the most remarkable and best studied instances
+of such an alteration is the Baltic, which, during the second half of
+the Glacial period, was in open and wide communication with the Arctic
+Ocean, and evidently had the same marine fauna as the White Sea. Since
+then, by the rising of the land of Northern Scandinavia and Finland,
+this great gulf of the Arctic Ocean has become an inland sea, with
+a narrow outlet into the North Sea, and its water, in consequence
+of the excess of the fresh water pouring into it over the loss by
+evaporation, has been so much diluted as to be nearly fresh at its
+northern extremities: and yet nine species, the origin of which from
+the Arctic Ocean can be proved, have survived the changes, propagating
+their species, agreeing with their brethren in the Arctic Ocean in
+every point, but remaining comparatively smaller. On the other hand,
+fishes which we must regard as true freshwater fishes, like the Rudd,
+Roach, Pike, Perch, enter freely the brackish water of the Baltic.<a id="FNanchor_17" href="#Footnote_17" class="fnanchor">[17]</a>
+Instances of marine fishes<span class="pagenum" id="Page_205">[205]</span> being permanently retained in fresh water
+in consequence of geological changes are well known: thus <i>Cottus
+quadricornis</i> in the large lakes of Scandinavia; species of
+<i>Gobius</i>, <i>Blennius</i>, and <i>Atherina</i> in the lakes of
+Northern Italy; <i>Comephorus</i>, of the depths of the Lake of Baikal,
+which seems to be a dwarfed Gadoid. <i>Carcharias gangeticus</i> in
+inland lakes of the Fiji Islands, is another instance of a marine fish
+which has permanently established itself in fresh water.</p>
+
+<p>In the miocene formation of Licata in Sicily, in which fish remains
+abound, numerous Cyprinoids are mixed with littoral and pelagic
+forms. Sauvage found in 450 specimens from that locality, not less
+than 266, which were Leucisci, Alburni, or Rhodei. Now, although it
+is quite possible that in consequence of a sudden catastrophe the
+bodies of those Cyprinoids were carried by a freshwater current into,
+and deposited on the bottom of, the sea, the surmise that they lived
+together with the littoral fishes in the brackish water of a large
+estuary, which was not rarely entered by pelagic forms, is equally
+admissible. And, if confirmed by other similar observations, this
+instance of a mixture of forms which are now strictly freshwater or
+marine, may have an important bearing on the question to what extent
+fishes have in time changed their original habitat.</p>
+
+<p>Thus there is a constant exchange of species in progress between the
+freshwater and marine faunæ, and in not a few cases it would seem
+almost arbitrary to refer a genus or even larger group of fishes
+to one or the other; yet there are certain groups of fishes which
+entirely, or with but few exceptions are, and, apparently, during
+the whole period of their existence have been, inhabitants either of
+the sea or of fresh water; and as the agencies operating upon the
+distribution of marine fishes differ greatly from those influencing
+the dispersal of freshwater fishes, the two series must be treated
+separately. The most obvious fact that dry land, which<span class="pagenum" id="Page_206">[206]</span> intervenes
+between river systems, offers to the rapid spreading of a freshwater
+fish an obstacle which can be surmounted only exceptionally or by a
+most circuitous route, whilst marine fishes may readily and voluntarily
+extend their original limits, could be illustrated by a great number
+of instances. Without entering into details, it may suffice to state
+as the general result, that no species or genus of freshwater fishes
+has anything like the immense range of the corresponding categories
+of marine fishes; and that, with the exception of the Siluroids,
+no other freshwater family is so widely spread as the families of
+marine fishes. Surface temperature or climate which is, if not the
+most, one of the most important physical factors in the limitation
+of freshwater fishes, similarly affects the distribution of marine
+fishes, but in a less degree, and only those which live near to the
+shore or the surface of the ocean; whilst it ceases to exercise its
+influence in proportion to the depth, the true deep-sea forms being
+entirely exempt from its operation. Light, which is pretty equally
+distributed over the localities inhabited by freshwater fishes, cannot
+be considered as an important factor in their distribution, but it
+contributes towards constituting the impassable barrier between the
+surface and abyssal forms of marine fishes. Altitude has stamped the
+fishes of the various Alpine provinces of the globe with a certain
+character, and limited their distribution; but the number of these
+Alpine forms is comparatively small, ichthyic life being extinguished
+at great elevations even before the mean temperature equals that of the
+high latitudes of the Arctic region, in which some freshwater fishes
+flourish. On the other hand, the depths of the ocean, far exceeding the
+altitude of the highest mountains, still swarm with forms specially
+adapted for abyssal life. That other physical conditions of minor and
+local importance, under which fresh water fishes live, and by which
+their dispersal is regulated, are more complicated than similar ones
+of the ocean, is<span class="pagenum" id="Page_207">[207]</span> probable, though perhaps less so than is generally
+supposed: for the fact is that the former are more accessible to
+observation than the latter, and are, therefore, more generally and
+more readily comprehended and acknowledged. Thus, not only because many
+of the most characteristic forms of the marine and freshwater series
+are found, on taking a broader view of the subject, to be sufficiently
+distinct, but also because their distribution depends on causes
+different in their nature as well as the degree of their action, it
+will be necessary to treat of the two series separately. Whether the
+oceanic areas correspond in any way to the terrestrial will be seen in
+the sequel.</p>
+
+  <div class="figcenter" id="fig103" style="max-width: 372px">
+     <img
+    class="p1"   
+    src="images/fig103.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 103.—Ganoid scales of <i>Tetragonolepis</i>.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_208">[208]</span></p>
+
+<h2 class="smaller">CHAPTER XVII.<br>
+<span class="subhed">THE DISTRIBUTION OF FRESHWATER FISHES.</span></h2></div>
+
+<p>Having shown above that numerous marine fishes enter fresh waters, and
+that some of them have permanently established themselves therein,
+we have to eliminate from the category of freshwater fishes all such
+adventitious elements. They are derived from forms, the distribution
+of which is regulated by other agencies, and which, therefore, would
+obscure the relations of the faunæ of terrestrial regions if they were
+included in them. They will be mentioned with greater propriety along
+with the fishes constituting the fauna of the brackish water.</p>
+
+<p>True freshwater fishes are the following families and groups only:—</p>
+
+<table class="smaller">
+  <tr>
+    <td class="cht">Dipnoi</td>
+    <td class="ctr">with</td>
+    <td class="right">4</td>
+    <td class="ctr">species.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Acipenseridæ and<br>
+                    Polyodontidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">26</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Amiidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Polypteridæ.</td>
+    <td class="ctr">„</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Lepidosteidæ.</td>
+    <td class="ctr">„</td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Percina</td>
+    <td class="ctr">„</td>
+    <td class="right">46</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Grystina</td>
+    <td class="ctr">„</td>
+    <td class="right">11</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Aphredoderidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Centrarchina</td>
+    <td class="ctr">„</td>
+    <td class="right">26</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Dules</td>
+    <td class="ctr">„</td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Nandidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Polycentridæ</td>
+    <td class="ctr">„</td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Labyrinthici</td>
+    <td class="ctr">„</td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Luciocephalidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Gastrosteus</td>
+    <td class="ctr">„</td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Ophiocephalidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">31</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Mastacembelidaæ</td>
+    <td class="ctr">„</td>
+    <td class="right">13</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Chromides</td>
+    <td class="ctr">„</td>
+    <td class="right">105</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Comephoridæ</td>
+    <td class="ctr">„</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Gadopsidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Siluridæ</td>
+    <td class="ctr">„</td>
+    <td class="right">572</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Characinidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">261</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Haplochitonidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Salmonidæ (3 genera excepted)</td>
+    <td class="ctr">„</td>
+    <td class="right">135</td>
+    <td class="ctr">„<span class="pagenum" id="Page_209">[209]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht">Percopsidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Galaxiidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">15</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Mormyridæ (and Gymnarchidæ)</td>
+    <td class="ctr">„</td>
+    <td class="right">52</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Esocidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">8</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Umbridæ</td>
+    <td class="ctr">„</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Cyprinodontidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">112</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Heteropygii</td>
+    <td class="ctr">„</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Cyprinidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">724</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Kneriidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Hyodontidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Osteoglossidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Notopteridæ</td>
+    <td class="ctr">„</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Gymnotidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">20</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Symbranchidæ</td>
+    <td class="ctr">„</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Petromyzontidæ</td>
+    <td class="ctrb">„</td>
+    <td class="rightb">12</td>
+    <td class="ctrb">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Total</td>
+    <td class="ctrbd"></td>
+    <td class="rightbd">2269</td>
+    <td class="ctrbd">species.</td>
+  </tr>
+
+</table>
+
+<p>As in every other class of animals, these freshwater genera and
+families vary greatly with regard to the extent of their geographical
+range; some extend over the greater half of the continental areas,
+whilst others are limited to one continent only, or even to a very
+small portion of it. As a general rule, a genus or family of freshwater
+fishes is regularly dispersed and most developed within a certain
+district, the species and individuals becoming scarcer towards the
+periphery as the type recedes more from its central home, some outposts
+being frequently pushed far beyond the outskirts of the area occupied
+by it. But there are not wanting those remarkable instances of closely
+allied forms occurring, almost isolated, at most distant points,
+without being connected by allied species in the intervening space;
+or of members of the same family, genus, or species inhabiting the
+opposite shores of an ocean, and separated by many degrees of abyssal
+depths. We mention of a multitude of such instances the following
+only:—</p>
+
+
+<p class="p1"><i>A</i>. Species identical in distant continents—</p>
+
+<p>1. A number of species inhabiting Europe and the temperate parts of
+eastern North America, as <i>Perca fluviatilis</i>, <i>Gastrosteus
+pungitius</i>, <i>Lota vulgaris</i>, <i>Salmo solar</i>, <i>Esox
+lucius</i>, <i>Acipenser sturio</i>, <i>Acipenser maculosus</i>, and
+several Petromyzonts.</p>
+
+<p><span class="pagenum" id="Page_210">[210]</span></p>
+
+<p>2. <i>Lates calcarifer</i> is common in India as well as in Queensland.</p>
+
+<p>3. <i>Galaxias attenuatus</i> inhabits Tasmania, New Zealand, the
+Falkland Islands, and the southernmost part of the South American
+continent.</p>
+
+<p>4. Several Petromyzonts enter the fresh waters of Tasmania, South
+Australia, New Zealand, and Chili.</p>
+
+
+<p class="p1"><i>B.</i> Genera identical in distant continents—</p>
+
+<p>1. The genus <i>Umbra</i>, so peculiar a form as to be the type of a
+distinct family consisting of two most closely allied species only, one
+of which is found in the Atlantic States of North America, the other in
+the system of the Danube.</p>
+
+<p>2. A very distinct genus of Sturgeons, <i>Scaphirhynchus</i>,
+consisting of two species only, one inhabiting fresh waters of Central
+Asia, the other the system of the Mississippi.</p>
+
+<p>3. A second most peculiar genus of Sturgeons, <i>Polyodon</i>, consists
+likewise of two species only, one inhabiting the Mississippi, the other
+the Yang-tse-kiang.</p>
+
+<p>4. <i>Amiurus</i>, a Siluroid, and <i>Catostomus</i>, a Cyprinoid
+genus, both well represented in North America, occur in a single
+species in temperate China.</p>
+
+<p>5. <i>Lepidosiren</i> is represented by one species in tropical
+America, and by the second in tropical Africa (<i>Protopterus</i>).</p>
+
+<p>6. <i>Notopterus</i> consists of three Indian and two West African
+species.</p>
+
+<p>7. <i>Mastacembelus</i> and <i>Ophiocephalus</i>, genera characteristic
+of the Indian region, emerge severally by a single species in West and
+Central Africa.</p>
+
+<p>8. <i>Symbranchus</i> has two Indian and one South American species.</p>
+
+<p>9. <i>Prototroctes</i>, the singular antarctic analogue of
+<i>Coregonus</i>, consists of two species, one in the south of
+Australia the other in New Zealand.</p>
+
+<p><span class="pagenum" id="Page_211">[211]</span></p>
+
+<p>10. <i>Galaxias</i> is equally represented in Southern Australia, New
+Zealand, and the southern parts of South America.</p>
+
+
+<p class="p1"><i>C.</i> Families identical in distant continents—</p>
+
+<p>1. The <i>Labyrinthici</i>, represented in Africa by 5, and in India by
+25 species.</p>
+
+<p>2. The <i>Chromides</i>, represented in Africa by 25, and in South
+America by 80 species.</p>
+
+<p>3. The <i>Characinidæ</i>, represented in Africa by 35, and in South
+America by 226 species.</p>
+
+<p>4. The <i>Haplochitonidæ</i>, represented in Southern Australia by one,
+in New Zealand by one, and in Patagonia by a third species.</p>
+
+<p>This list could be much increased from the families of <i>Siluridæ</i>
+and <i>Cyprinidæ</i>, but as these have a greater range than the other
+Freshwater fishes, they do not illustrate with equal force the object
+for which the list has been composed.</p>
+
+<hr class="tb">
+
+<p>The ways in which the dispersal of Freshwater fishes has been effected
+were various; they are probably all still in operation, but most work
+so slowly and imperceptibly as to escape direct observation; perhaps,
+they will be more conspicuous, after science and scientific inquiry
+shall have reached to a somewhat greater age. From the great number
+of freshwater forms which we see at this present day acclimatised in,
+gradually acclimatising themselves in, or periodically or sporadically
+migrating into, the sea, we must conclude that, under certain
+circumstances, salt water may cease to be an impassable barrier at some
+period of the existence of freshwater species, and that many of them
+have passed from one river through salt water into another. Secondly,
+the headwaters of some of the grandest rivers, the mouths of which are
+at opposite ends of the continents which they drain, are<span class="pagenum" id="Page_212">[212]</span> sometimes
+distant from each other a few miles only; the intervening space may
+have been easily bridged over for the passage of fishes by a slight
+geological change affecting the level of the watershed, or even by
+temporary floods; and a communication of this kind, if existing for a
+limited period only, would afford the ready means of an exchange of
+a number of species previously peculiar to one or the other of those
+river or lake systems. Some fishes, provided with gill-openings so
+narrow that the water moistening the gills cannot readily evaporate;
+and endowed, besides, with an extraordinary degree of vitality, like
+many Siluroids (<i>Clarias</i>, <i>Callichthys</i>), Eels, etc., are
+enabled to wander for some distance over land, and may thus reach
+a water-course leading them thousands of miles from their original
+home. Finally, fishes or their ova may be accidentally carried by
+waterspouts, by aquatic birds or insects, to considerable distances.</p>
+
+<p>Freshwater fishes of the present fauna were already in existence when
+the great changes of the distribution of land and water took place
+in the tertiary epoch; and having stated that salt water is not an
+absolute barrier to the spreading of Freshwater fishes, we can now
+more easily account for those instances of singular disconnection of
+certain families or genera. It is not necessary to assume that there
+was a continuity of land stretching from the present coast of Africa
+to South America, or from South America to New Zealand and Australia,
+to explain the presence of identical forms at so distant localities;
+it suffices to assume that the distances were lessened by intervening
+archipelagoes, or that an oscillation has taken place in the level of
+the land area.</p>
+
+<p>Dispersal of a type over several distant continental areas may be
+evidence of its great antiquity, but it does not prove that it is of
+greater antiquity than another limited to one region only. Geological
+evidence is the only proof of the antiquity of a type. Thus, although
+the <i>Dipnoi</i> occur on the<span class="pagenum" id="Page_213">[213]</span> continents of Africa, South America,
+and Australia, and their present distribution is evidently the
+consequence of their wide range in palæozoic and secondary epochs; the
+proof of their high antiquity can be found in their fossil remains
+only. For, though the Siluroids have a still greater range, their wide
+distribution is of comparatively recent date, as the few fossil remains
+that have been found belong to the tertiary epoch. The rapidity of
+dispersal of a type depends entirely on its facility to accommodate
+itself to a variety of physical conditions, and on the degree of
+vitality by which it is enabled to survive more or less sudden changes
+under unfavourable conditions; proof of this is afforded by the family
+of Siluroids, many of which can suspend for some time the energy of
+their respiratory functions, and readily survive a change of water.</p>
+
+<hr class="tb">
+
+<p>To trace the geological sequence of the distribution of an ichthyic
+type, and to recognise the various laws which have governed, and
+are still governing its dispersal, is one of the ultimate tasks of
+Ichthyology. But the endeavour to establish by means of our present
+fragmentary geological knowledge the divisions of the fauna of the
+globe, leads us into a maze of conflicting evidence; or, as Mr.
+Wallace truly observes, “any attempt to exhibit the regions of former
+geological ages in combination with those of our own period must lead
+to confusion.” Nevertheless, as the different types of animals found
+at the present day within a particular area have made their appearance
+therein at distant periods, we should endeavour to decide as far as
+we can, in an account of the several zoo-geographical divisions, the
+following questions:—</p>
+
+<p>1. Which of the fishes of an area should be considered to be the
+remnants of <i>ancient</i> types, probably spread over much larger
+areas in preceding epochs?</p>
+
+<p><span class="pagenum" id="Page_214">[214]</span></p>
+
+<p>2. Which of them are to be considered to be <i>autochthont</i> species,
+that is, forms which came in the tertiary epoch or later into existence
+within the area to which they are still limited, or from which they
+have since spread?</p>
+
+<p>3. Which are the forms which must be considered to be <i>immigrants</i>
+from some other region?</p>
+
+<p>The mode of division of the earth’s surface into zoological regions
+or areas now generally adopted, is that proposed by Mr. Sclater,
+which recommends itself as most nearly agreeing with the geographical
+divisions. These regions are as follows:—</p>
+
+<div class="blockquot">
+
+<p class="p-left">I. <span class="smcap">Palæogæa.</span></p>
+
+<div class="blockquot">
+
+<p class="hangingindent">1. The <i>Palæarctic</i> region; including Europe,
+temperate Asia, and North Africa.</p>
+
+<p class="hangingindent">2. The <i>Ethiopian</i> region; including Africa, south
+of the Sahara, Madagascar, and the Mascarene Islands;
+also Southern Arabia.</p>
+
+<p class="hangingindent">3. The <i>Indian</i> region; including India south of the
+Himalayas, to Southern China, Borneo, and Java.</p>
+
+<p class="hangingindent">4. The <i>Australian</i> region; including Australia, the
+Pacific Islands, Celebes, and Lombock.</p>
+</div>
+
+<p class="p-left">II. <span class="smcap">Neogæa.</span></p>
+
+<div class="blockquot">
+
+<p class="hangingindent">5. The <i>Nearctic</i> region; including North America to
+Northern Mexico.</p>
+
+<p class="hangingindent">6. The <i>Neotropical</i> region; including South
+America, the West Indies, and Southern Mexico.</p>
+</div>
+</div>
+
+<p>Comparatively few classes and orders of animals have been carefully
+studied with regard to their geographical distribution, but the
+majority of those which have been examined show that the difference
+of latitude is accompanied by a greater dissimilarity of indigenous
+species than that of<span class="pagenum" id="Page_215">[215]</span> longitude, and that a main division into an old
+world and new world fauna is untenable. More especially the Freshwater
+fishes, with which we are here solely concerned, have been spread in
+<i>circumpolar</i> zones, and in a but limited degree from north to
+south. No family, much less a genus, ranges from the north to the
+south, whilst a number of families and genera make the entire circuit,
+and some species more than half of the circuit round the globe within
+the zone to which they belong. Not even the Cyprinoids and Siluroids,
+which are most characteristic of the freshwater fauna of our period,
+are an exception to this. Temperature and climate, indeed, are the
+principal factors by which the character of the freshwater fauna is
+determined; they form the barriers which interfere with the unlimited
+dispersal of an ichthyic type, much more than mountain ranges, deserts,
+or oceans. Hence the tropical zone is an impassable barrier to the
+northern Freshwater fish in its progress towards the south; where
+a similarly temperate climate obtains in the southern hemisphere,
+fish-forms appear <i>analogous</i> to those of the north, but
+<i>genetically</i> and <i>structurally distinct</i>.</p>
+
+<p>The similarity which obtains in fishes at somewhat distant points
+of the same degree of longitude, rarely extends far, and is due to
+the natural tendency of every animal to spread as far as physical
+conditions will permit. Between two regions situated north and south
+of each other there is always a debateable border ground, in parts of
+which sometimes the fishes of the one, sometimes those of the other,
+predominate, and which is, in fact, a <i>band</i> of demarcation.
+Within this band the regions overlap each other; therefore, their
+border <i>lines</i> are rarely identical, and should be determined by
+the northern and southernmost extent of the most characteristic types
+of each region. Thus, for instance, in China, a broad band intervenes
+between temperate and tropical Asia, in which these two faunæ mix, and
+the actual northern<span class="pagenum" id="Page_216">[216]</span> border line of the tropical fauna is north of the
+southern border line of temperate Asia.</p>
+
+<p>It is the aim of every philosophical classification to indicate the
+degree of affinity which obtains between the various divisions; but
+the mode of division into six equivalent regions, as given above, does
+not fulfil this aim with regard to Freshwater fishes, the distribution
+of which allows of further generalisation and subdivision. The two
+families, <i>Cyprinidæ</i> and <i>Siluridæ</i>, of which the former
+yields a contingent of one-third, and the latter of one-fourth of
+all the freshwater species known of our period, afford most valuable
+guidance for the valuation of the degrees of affinity between the
+various divisions. The Cyprinoids may be assumed to have taken their
+origin in the Alpine region, dividing the temperate and tropical parts
+of Asia; endowed with a greater capability of acclimatising themselves
+in a temperate as well as tropical climate than any other family of
+freshwater fishes, they spread north and south as well as east and
+west; in the preglacial epoch they reached North America, but they have
+not had time to penetrate into South America, Australia, or the islands
+of the Pacific. The Siluroids, principally fishes of the sluggish
+waters of the plains, and well adapted for surviving changes of the
+water in which they live, for living in mud or sea-water, flourish
+most in the tropical climate, in which this type evidently had its
+origin. They came into existence after the Cyprinoids, fossil remains
+being known only from tertiary deposits in India, none from Europe.
+They rapidly spread over the areas of land within the tropical zone,
+reaching northern Australia from India, and one species even immigrated
+into the Sandwich Islands, probably from South America. The Coral
+Islands of the Pacific still remain untenanted by them. Their progress
+into temperate regions was evidently slow, only very few species
+penetrating into the temperate parts of Asia and Europe; and the North
+American species,<span class="pagenum" id="Page_217">[217]</span> although more numerous, showing no great variety of
+structure, all belonging to the same group (<i>Amiurina</i>). Towards
+the south their progress was still slower, Tasmania, New Zealand, and
+Patagonia being without representatives, whilst the streams of the
+Andes of Chili are inhabited by a few dwarfed forms identical with such
+as are characteristic of similar localities in the more northern and
+warmer parts of the South American continent.</p>
+
+<p>After these preliminary remarks we propose the following division of
+the fauna of Freshwater fishes:—</p>
+
+<p class="hangingindent">I. <span class="smcap">The Northern Zone</span>.—Characterised by Acipenseridæ. Few
+Siluridæ. Numerous Cyprinidæ. Salmonidæ, Esocidæ.</p>
+
+<p class="hangingindent1">1. <i>Europo-Asiatic or Palæarctic Region</i>.—Characterised by
+absence of osseous Ganoidei; Cobitidæ and Barbus numerous.</p>
+
+<p class="hangingindent1">2. <i>North American Region</i>.—Characterised by osseous Ganoidei,
+Amiurina, and Catostomina; but no Cobitidæ or Barbus.</p>
+
+<p class="hangingindent">II. <span class="smcap">The Equatorial Zone</span>.—Characterised by the development of
+Siluridæ.</p>
+
+<p class="hangingindent1">A. <i>Cyprinoid Division</i>.—Characterised by presence of Cyprinidæ
+and Labyrinthici.</p>
+
+<p class="hangingindent2">1. <i>Indian Region</i>.—Characterised by [absence of Dipnoi<a id="FNanchor_18" href="#Footnote_18" class="fnanchor">[18]</a>]
+Ophiocephalidæ, Mastacembelidæ. Cobitidæ numerous.</p>
+
+<p class="hangingindent2">2. <i>African Region</i>.—Characterised by presence of Dipnoi and
+Polypteridæ. Chromides and Characinidæ numerous. Mormyridæ. Cobitidæ
+absent.</p>
+
+<p><span class="pagenum" id="Page_218">[218]</span></p>
+
+<p class="hangingindent1">B. <i>Acyprinoid Division</i>.—Characterised by absence of Cyprinidæ
+and Labyrinthici.</p>
+
+<p class="hangingindent2">1. <i>Tropical American Region</i>.—Characterised by presence of
+Dipnoi. Chromides and Characinidæ numerous. Gymnotidæ.</p>
+
+<p class="hangingindent2">2. <i>Tropical Pacific Region</i>.—Characterised by presence of
+Dipnoi. Chromides and Characinidæ absent.</p>
+
+<p class="hangingindent">III. <span class="smcap">The Southern Zone</span>.—Characterised by absence of
+Cyprinidæ, and scarcity of Siluridæ. Haplochitonidæ and Galaxiidæ
+represent the Salmonoids and Esoces of the Northern zone. One region
+only.</p>
+
+<p class="hangingindent1">1. <i>Antarctic Region</i>.—Characterised by the small number of
+species; the fishes of—</p>
+
+<p class="hangingindent2"><i>a</i>. The Tasmanian sub-region; <i>b</i>. The New Zealand
+sub-region; <i>c</i>. The Patagonian sub-region;</p>
+
+<p class="p-left">being almost identical.<a id="FNanchor_19" href="#Footnote_19" class="fnanchor">[19]</a></p>
+
+<p>In the following detailed account we begin with a description of the
+equatorial zone, this being the one from which the two principal
+families of freshwater fishes seem to have spread.</p>
+
+<h3>I. <span class="smcap">Equatorial Zone</span>.</h3>
+
+<p>Roughly speaking, the borders of this zoological zone coincide with
+the geographical limits of the tropical zone, the tropics of the
+Cancer and Capricorn; its characteristic forms, however, extend in
+undulating lines several degrees north and southwards. Commencing from
+the west coast of<span class="pagenum" id="Page_219">[219]</span> Africa the desert of the Sahara forms a well-marked
+boundary between the equatorial and northern zones; as the boundary
+approaches the Nile it makes a sudden sweep towards the north as far as
+Northern Syria (<i>Mastacembelus</i>, near Aleppo, and in the Tigris;
+<i>Clarias</i> and <i>Chromides</i>, in the lake of Galilee); crosses
+through Persia and Afghanistan (<i>Ophiocephalus</i>), to the southern
+ranges of the Himalayas, and follows the course of the Yang-tse-Kiang,
+which receives its contingent of equatorial fishes through its
+southern tributaries. Its continuation through the North Pacific may
+be considered to be indicated by the tropic which strikes the coast
+of Mexico at the southern end of the Gulf of California. Equatorial
+types of South America are known to extend so far northwards; and by
+following the same line the West India Islands are naturally included
+in this zone.</p>
+
+<p>Towards the south the equatorial zone embraces the whole of Africa
+and Madagascar, and seems to extend still farther south in Australia,
+its boundary probably following the southern coast of that continent;
+the detailed distribution of the freshwater fishes of South-Western
+Australia has been but little studied, but the few facts which we
+know show that the tropical fishes of Queensland follow the principal
+water-course of that country, the Murray River, far towards the
+south and probably to its mouth. The boundary-line then stretches
+northwards of Tasmania and New Zealand, coinciding with the tropic
+until it strikes the western slope of the Andes, on the South American
+Continent, where it again bends southwards to embrace the system of the
+Rio de la Plata.</p>
+
+<p>The equatorial zone is divided into four regions:—</p>
+
+<div class="parent">
+<ul class="left" style="margin-top: 0em">
+  <li>A. The Indian region.</li>
+  <li>B. The African region.</li>
+  <li>C. The Tropical American region.</li>
+  <li>D. The Tropical Pacific region.</li>
+</ul>
+</div>  
+
+<p><span class="pagenum" id="Page_220">[220]</span></p>
+
+<p>These four regions diverge into two well-marked divisions, one of
+which is characterised by the presence of Cyprinoid fishes, combined
+with the development of Labyrinthici; whilst in the other both these
+types are absent. The boundary between the Cyprinoid and Acyprinoid
+division seems to follow Wallace’s line, a line drawn from the south of
+the Philippines between Borneo and Celebes, and farther south between
+Bali and Lombock. Borneo abounds in Cyprinoids; from the Philippine
+Islands a few only are known at present, and in Bali two species have
+been found; but none are known from Celebes or Lombock, or from islands
+situated farther east of them.<a id="FNanchor_20" href="#Footnote_20" class="fnanchor">[20]</a></p>
+
+<p>Taking into consideration the manner in which Cyprinoids and Siluroids
+have been dispersed, we are obliged to place the Indian region as
+the first in the order of our treatment; and indeed the number of
+its freshwater fishes, which appear to have spread from it into the
+neighbouring regions, far exceeds that of the species which it has
+received from them.</p>
+
+<hr class="tb">
+
+<p>A. The <span class="smcap">Indian Region</span> comprises the whole continent of Asia
+south of the Himalayas and the Yang-tse-kiang; it includes the islands
+to the west of Wallace’s line. Towards the north-east the island of
+Formosa, which also by other parts of its fauna leans more towards the
+equatorial zone, has received some characteristic Japanese Freshwater
+fishes, for instance, the singular Salmonoid <i>Plecoglossus</i>.
+Within the geographical boundaries of China the Freshwater fishes of
+the tropics pass gradually into those of the northern zone, both being
+separated by a broad debateable ground. The affluents of the great
+river traversing<span class="pagenum" id="Page_221">[221]</span> this district are more numerous from the south than
+from the north, and carry the southern fishes far into the temperate
+zone. The boundary of this region towards the north-west is scarcely
+better defined. Before Persia passed through the geological changes by
+which its waters were converted into brine and finally dried up, it
+seems to have been inhabited by many characteristic Indian forms, of
+which a few still survive in the tract intervening between Afghanistan
+and Syria; <i>Ophiocephalus</i> and <i>Discognathus</i> have each at
+least one representative, <i>Macrones</i> has survived in the Tigris,
+and Mastacembelus has penetrated as far as Aleppo. Thus, Freshwater
+fishes belonging to India, Africa, and Europe, are intermingled in a
+district which forms the connecting link between the three continents.
+Of the freshwater fishes of Arabia we are perfectly ignorant; so much
+only being known that the Indian <i>Discognathus lamta</i> occurs in
+the reservoirs of Aden, having, moreover, found its way to the opposite
+African coast; and that the ubiquitous Cyprinodonts flourish in
+brackish pools of Northern Arabia.</p>
+
+<p>The following is the list of the forms of freshwater fishes inhabiting
+this region:<a id="FNanchor_21" href="#Footnote_21" class="fnanchor">[21]</a>—</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="cht">Percina—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Lates<a id="FNanchor_22" href="#Footnote_22" class="fnanchor">[22]</a> [Africa, Australia]</td>
+    <td class="right">1</td>
+    <td class="ctr">species.</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Nandina</i></td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Labyrinthici [Africa]</td>
+    <td class="right">25</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Luciocephalidæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Ophiocephalidæ</i> [1 species in Africa]</td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Mastacembelidæ</i> [3 species in Africa]</td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Chromides [Africa, South America]</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Etroplus</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„<span class="pagenum" id="Page_222">[222]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Siluridæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Clariina [Africa]</td>
+    <td class="right">12</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Chacina</i></td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Silurina [Africa, Palæarct.]</td>
+    <td class="right">72</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Bagrina [Africa]</td>
+    <td class="right">50</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Ariina [Africa, Australia, South America]</td>
+    <td class="right">40</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Bagariina</i></td>
+    <td class="right">20</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Rhinoglanina [Africa]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Hypostomatina [South America]</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Cyprinodontidæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Carnivoræ [Palæarct., North America, Africa, South America]</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Haplochilus [Africa, South America, North America, Japan]</td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Cyprinidæ [Palæarct., N. America, Africa]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Cyprinina [Palæarct., N. America, Africa]</td>
+    <td class="right">190</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Rasborina</i> [Africa, 1 species]</td>
+    <td class="right">20</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Semiplotina</i></td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Danionina [Africa]</td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Abramidina [Palæarct., N. Amer., Africa]</td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Homalopterina</i></td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Cobitidina [Palæarct.]</td>
+    <td class="right">50</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Osteoglossidæ [Africa, Australia, S. America]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Notopteridæ [Africa]</td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Symbranchidæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Amphipnous</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Monopterus</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Symbranchus [1 species in S. America]</td>
+    <td class="rightb">2</td>
+    <td class="ctrb">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"></td>
+    <td class="rightbd">625</td>
+    <td class="ctrbd">species.</td>
+  </tr>
+</table>
+
+<p>In analysing this list we find that out of 39 families or groups of
+freshwater fishes 12 are represented in this region, and that 625
+species are known to occur in it; a number equal to two-sevenths of
+the entire number of freshwater fishes known. This large proportion
+is principally due to the development of numerous local forms of
+Siluroids and<span class="pagenum" id="Page_223">[223]</span> Cyprinoids, of which the former show a contingent
+of about 200, and the latter of about 330 species. The combined
+development of those two families, and their undue preponderance over
+the other freshwater types, is therefore the principal characteristic
+of the Indian region. The second important character of its fauna is
+the apparently total absence of Ganoid and Cyclostomous fishes. Every
+other region has representatives of either Ganoids or Cyclostomes,
+some of both. However, attention has been directed to the remarkable
+coincidence of the geographical distribution of the <i>Sirenidæ</i>
+and <i>Osteoglossidæ</i>, and as the latter family is represented in
+Sumatra and Borneo, it may be reasonably expected that a Dipnoous form
+will be found to accompany it. The distribution of the <i>Sirenidæ</i>
+and <i>Osteoglossidæ</i> is as follows:—</p>
+
+<table class="smaller">
+  <tr>
+    <td class="ctr" colspan="2"><i>Tropical America.</i></td>
+  </tr>
+
+  <tr>
+    <td class="cht9">Lepidosiren paradoxa.</td>
+    <td class="cht3">Osteoglossum bicirrhosum.</td>
+  </tr>
+
+  <tr>
+    <td class="cht9"></td>
+    <td class="cht3">Arapaima gigas.</td>
+  </tr>
+
+  <tr>
+    <td class="ctr3" colspan="2"><i>Tropical Australia.</i></td>
+  </tr>
+
+  <tr>
+    <td class="cht9">Ceratodus forsteri.</td>
+    <td class="cht3">Osteoglossum leichardti.</td>
+  </tr>
+
+  <tr>
+    <td class="cht9">Ceratodus miolepis.</td>
+    <td class="cht3"></td>
+  </tr>
+
+  <tr>
+    <td class="ctr3" colspan="2"><i>East Indian Archipelago.</i></td>
+  </tr>
+
+  <tr>
+    <td class="ctr2">?</td>
+    <td class="cht3">Osteoglossum formosum.</td>
+  </tr>
+
+  <tr>
+    <td class="ctr3" colspan="2"><i>Tropical Africa.</i></td>
+  </tr>
+
+  <tr>
+    <td class="cht9">Protopterus annectens.</td>
+    <td class="cht3">Heterotis niloticus.</td>
+  </tr>
+</table>
+
+<p>Not only are the corresponding species found within the same region,
+but also in the same river systems; and although such a connection
+may and must be partly due to a similarity of habit, yet the identity
+of this singular distribution is so striking that it can only be
+accounted for by assuming that the <i>Osteoglossidæ</i> are one of the
+earliest Teleosteous types which have been contemporaries of and have
+accompanied<span class="pagenum" id="Page_224">[224]</span> the present Dipnoi since or even before the beginning of
+the tertiary epoch.</p>
+
+<p>Of the <i>autochthont</i> freshwater fishes of the Indian region,
+some are still limited to it, viz., the <i>Nandina</i>, the
+<i>Luciocephalidæ</i> (of which one species only exists in the
+Archipelago), of Siluroids the <i>Chacina</i> and <i>Bagariina</i>,
+of Cyprinoids the <i>Semiplotina</i> and <i>Homalopterina</i>; others
+very nearly so, like the <i>Labyrinthici</i>, <i>Ophiocephalidæ</i>,
+<i>Mastacembelidæ</i>, of Siluroids the <i>Silurina</i>, of Cyprinoids
+the <i>Rasborina</i> and <i>Danionina</i>, and <i>Symbranchidæ</i>.</p>
+
+<p>The regions with which the Indian has least similarity are the North
+American and Antarctic, as they are the most distant. Its affinity to
+the other regions is of a very different degree:—</p>
+
+<p>1. Its affinity to the Europo-Asiatic region is indicated almost
+solely by three groups of Cyprinoids, viz., the <i>Cyprinina</i>,
+<i>Abramidina</i>, and <i>Cobitidina</i>. The development of these
+groups north and south of the Himalayas is due to their common origin
+in the highlands of Asia; but the forms which descended into the
+tropical climate of the south are now so distinct from their northern
+brethren that most of them are referred to distinct genera. The genera
+which are still common to both regions are only the true Barbels
+(<i>Barbus</i>), a genus which, of all Cyprinoids, has the largest
+range over the old world, and of which some 160 species have been
+described; and, secondly, the Mountain Barbels (<i>Schizothorax</i>,
+etc.), which, peculiar to the Alpine waters of Central Asia, descend
+a short distance only towards the tropical plains, but extend farther
+into rivers within the northern temperate districts. The origin and the
+laws of the distribution of the <i>Cobitidina</i> appear to have been
+identical with those of <i>Barbus</i>, but they have not spread into
+Africa.</p>
+
+<p>If, in determining the degree of affinity between two<span class="pagenum" id="Page_225">[225]</span> regions, we take
+into consideration the extent in which an exchange has taken place of
+the faunæ originally peculiar to each, we must estimate that obtaining
+between the freshwater fishes of the Europo-Asiatic and Indian regions
+as very slight indeed.</p>
+
+<p>2. There exists a great affinity between the Indian and African
+regions; seventeen out of the twenty-six families or groups found
+in the former are represented by one or more species in Africa,
+and many of the African species are not even generically different
+from the Indian. As the majority of these groups have many more
+representatives in India than in Africa, we may reasonably assume that
+the African species have been derived from the Indian stock; but this
+is probably not the case with the Siluroid group of <i>Clariina</i>,
+which with regard to species is nearly equally distributed between
+the two regions, the African species being referable to three genera
+(<i>Clarias</i>, <i>Heterobranchus</i>, <i>Gymnallabes</i>, with
+the subgenus <i>Channallabes</i>), whilst the Indian species belong
+to two genera only, viz. <i>Clarias</i> and <i>Heterobranchus</i>.
+On the other hand, the Indian region has derived from Africa one
+freshwater form only, viz. <i>Etroplus</i>, a member of the family
+of <i>Chromides</i>, so well represented in tropical Africa and
+South America. <i>Etroplus</i> inhabits Southern and Western India
+and Ceylon, and has its nearest ally in a Madegasse Freshwater fish,
+<i>Paretroplus</i>. Considering that other African Chromides have
+acclimatised themselves at the present day in saline water, we think it
+more probable that Etroplus should have found its way to India through
+the ocean than over the connecting land area; where, besides, it does
+not occur.</p>
+
+<p>3. A closer affinity between the Indian and Tropical American regions
+than is indicated by the character of the equatorial zone generally,
+does not exist. No genus of Freshwater fishes occurs in India and
+South America without being found in the intermediate African region,
+with two exceptions.<span class="pagenum" id="Page_226">[226]</span> Four small Indian Siluroids (<i>Sisor</i>,
+<i>Erethistes</i>, <i>Pseudecheneis</i>, and <i>Exostoma</i>) have been
+referred to the South American <i>Hypostomatina</i>; but it remains to
+be seen whether this combination is based upon a sufficient agreement
+of their internal structure, or whether it is not rather artificial.
+On the other hand, the occurrence and wide distribution in tropical
+America of a fish of the Indian family Symbranchidæ (<i>Symbranchus
+marmoratus</i>), which is not only congeneric with, but also most
+closely allied to, the Indian <i>Symbranchus bengalensis</i>, offers
+one of those extraordinary anomalies in the distribution of animals of
+which no satisfactory explanation can be given at present.</p>
+
+<p>4. The relation of the Indian region to the Tropical Pacific region
+consists only in its having contributed a few species to the poor
+fauna of the latter. This immigration must have taken place within
+a recent period, because some species now inhabit fresh waters of
+tropical Australia and the South Sea Islands without having in any
+way changed their specific characters, as <i>Lates calcarifer</i>,
+species of <i>Dules</i>, <i>Plotosus anguillaris</i>; others (species
+of <i>Arius</i>) are but little different from Indian congeners. All
+these fishes must have migrated by the sea; a supposition which is
+supported by what we know of their habits. We need not add that India
+has not received a single addition to its freshwater fish-fauna from
+the Pacific region.</p>
+
+<p>Before concluding these remarks on the Indian region, we must mention
+that peculiar genera of Cyprinoids and Siluroids inhabit the streams
+and lakes of its alpine ranges in the north. Some of them, like
+the Siluroid genera <i>Glyptosternum</i>, <i>Euglyptosternum</i>,
+<i>Pseudecheneis</i>, have a folded disk on the thorax between their
+horizontally spread pectoral fins; by means of this they adhere
+to stones at the bottom of the mountain torrents, and without it
+they would be swept away into the lower courses of the rivers.
+The Cyprinoid<span class="pagenum" id="Page_227">[227]</span> genera inhabiting similar localities, and the
+lakes into which the alpine rivers pass, such as <i>Oreinus</i>,
+<i>Schizothorax</i>, <i>Ptychobarbus</i>, <i>Schizopygopsis</i>,
+<i>Diptychus</i>, <i>Gymnocypris</i>, are distinguished by peculiarly
+enlarged scales near the vent, the physiological use of which has
+not yet been ascertained. These alpine genera extend far into the
+Europo-Asiatic region, where the climate is similar to that of their
+southern home. No observations have been made by which the altitudinal
+limits of fish life in the Himalayas can be fixed, but it is probable
+that it reaches the line of perpetual snow, as in the European Alps
+which are inhabited by Salmonoids. Griffith found an <i>Oreinus</i>
+and a Loach, the former in abundance, in the Helmund at Gridun Dewar,
+altitude 10,500 feet; and another Loach at Kaloo at 11,000 feet.</p>
+
+<hr class="tb">
+
+<p>B. <span class="smcap">The African Region</span> comprises the whole of the African
+continent south of the Atlas and the Sahara. It might have been
+conjectured that the more temperate climate of its southern extremity
+would have been accompanied by a conspicuous difference of the
+fish-fauna. But this is not the case; the difference between the
+tropical and southern parts of Africa consists simply in the gradual
+disappearance of specifically tropical forms, whilst Siluroids,
+Cyprinoids, and even Labyrinthici penetrate to its southern coast;
+no new form has entered to impart to South Africa a character
+distinct from the central portion of the continent. In the north-east
+the African fauna passes the Isthmus of Suez and penetrates into
+Syria; the system of the Jordan presenting so many African types
+that it has to be included in a description of the African region
+as well as of the Europo-Asiatic. This river is inhabited by three
+species of <i>Chromis</i>, one of <i>Hemichromis</i>, and <i>Clarias
+macracanthus</i>, a common fish of the Upper Nile. This infusion of
+African forms cannot be accounted for by any one of those accidental
+means of dispersal,<span class="pagenum" id="Page_228">[228]</span> as <i>Hemichromis</i> is not represented in the
+north-eastern parts of Africa proper, but chiefly on the west coast and
+in the Central African lakes.</p>
+
+<p>Madagascar clearly belongs to this region. Besides some Gobies
+and <i>Dules</i>, which are not true freshwater fishes, four
+<i>Chromides</i> are known. To judge from general accounts, its
+Freshwater fauna is poorer than might be expected; but, singular as it
+may appear, collectors have hitherto paid but little attention to the
+Freshwater fishes of this island. The fishes found in the freshwaters
+of the Seychelles and Mascarenes are brackish-water fishes, such as
+<i>Fundulus</i>, <i>Haplochilus</i>, <i>Elops</i>, <i>Mugil</i>, etc.</p>
+
+<p>The following is the list of the forms of Freshwater fishes inhabiting
+this region:—</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="cht">Dipnoi [Australia, Neotrop.]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Lepidosiren annectens</i></td>
+    <td class="right">1</td>
+    <td class="ctr">species.</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Polypteridæ</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Percina (Cosmopol.)—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Lates [India, Australia]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Labyrinthici [India]</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Ophiocephalidæ [India]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Mastacembelidæ [India]</td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Chromides [South America]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Chromis</i></td>
+    <td class="right">23</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Hemichromis</i></td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Paretroplus</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Siluridæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Clariina [India]</td>
+    <td class="right">14</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Silurina [India, Palæarct.]</td>
+    <td class="right">11</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Bagrina [India]</td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Pimelodina [South America]</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Ariina<a id="FNanchor_23" href="#Footnote_23" class="fnanchor">[23]</a> [India, Australia, S. Amer., Patagonia]</td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Doradina [South America]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4"><i>Synodontis</i></td>
+    <td class="right">15</td>
+    <td class="ctr">„<span class="pagenum" id="Page_229">[229]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Rhinoglanina [India]</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Malapterurina</i></td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Characinidæ [South America]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Citharinina</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Nannocharacina</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Tetragonopterina—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4"><i>Alestes</i></td>
+    <td class="right">14</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Crenuchina—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4"><i>Xenocharax</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Hydrocyonina—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4"><i>Hydrocyon</i></td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Distichodontina</i></td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Ichthyborina</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Mormyridæ</i> (<i>Gymnarchidæ</i>)</td>
+    <td class="right">51</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Cyprinodontidæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Carnivoræ [Palæarct., India, S. America—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Haplochilus [India, South America]</td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Fundulus [Palæarct., Nearct.]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Cyprinidæ [Palæarct., India, North America]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Cyprinina [Palæarct., India, N. America—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Labeo [India]</td>
+    <td class="right">6</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Barynotus [India]</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht4"><i>Abrostomus</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Discognathus lamta<a id="FNanchor_24" href="#Footnote_24" class="fnanchor">[24]</a> [India]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Barbus [Palæarct., India]</td>
+    <td class="right">35</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Rasborina [India]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Danionina [India]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4">Barilius [India]</td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Abramidina [Palæarct., India, N. America]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4"><i>Pelotrophus</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Kneriidæ</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Osteoglossidæ [India, Australia, South America]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht4"><i>Heterotis</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Pantodontidæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="chtb">Notopteridæ [India]</td>
+    <td class="rightb">2</td>
+    <td class="ctrb">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"></td>
+    <td class="rightbd">255</td>
+    <td class="ctrbd">species.</td>
+  </tr>
+</table>
+
+<p><span class="pagenum" id="Page_230">[230]</span></p>
+
+<p>Out of the 39 families or groups of freshwater fishes 15 are
+represented in the African region, or three more than in the Indian
+region; however of two of them, viz., the <i>Ophiocephalidæ</i> and
+<i>Mastacembelidæ</i>, a few species only have found their way into
+Africa. On the other hand, the number of species is much less, viz.
+255, which is only two-fifths of that of the known Indian species. The
+small degree of specialisation and localisation is principally due to
+the greater uniformity of the physical conditions of this continent,
+and to the almost perfect continuity of the great river systems,
+which take their origin from the lakes in its centre. This is best
+shown by a comparison of the fauna of the Upper Nile with that of the
+West African rivers. The number of species known from the Upper Nile
+amounts to 56, and of these not less than 25 are absolutely identical
+with West African species. There is an uninterrupted continuity of the
+fish-fauna from west to the north-east, and the species known to be
+common to both extremities may be reasonably assumed to inhabit also
+the great reservoirs of water in the centre of the continent. A greater
+dissimilarity is noticeable between the west and north-east fauna
+on the one hand, and that of the Zambezi on the other; the affinity
+between them is merely generic; and all the fishes hitherto collected
+in Lake Nyassa have proved to be distinct from those of the Nile, and
+even from those of other parts of the system of the Zambezi.</p>
+
+<p>Africa, unlike India, does not possess either alpine ranges or outlying
+archipelagoes, the fresh waters of which would swell the number of its
+indigenous species; but at a future time, when its fauna is better
+known than at present, it is possible that the great difference in the
+number of species between this and the Indian regions may be somewhat
+lessened.</p>
+
+<p>The most numerously-represented families are the Siluroids, with
+61 species; the Cyprinoids, with 52; the Mormyridæ, with 51; the
+Characinidæ, with 35; and the Chromides,<span class="pagenum" id="Page_231">[231]</span> with 29. There is not,
+therefore, that great preponderance of the two first families over the
+remaining, which we noticed in the Indian region; in Africa there is a
+comparatively greater variety of distinct Freshwater types, imparting
+to the study of its fauna an unflagging pleasure such as is scarcely
+gained by the study of the other region. With the forms peculiar to it
+there are combined those of India as well as South America.</p>
+
+<p>In Tropical Africa there are still remnants of Ganoids:
+<i>Protopterus</i> (<i>Lepidosiren</i>) <i>annectens</i>
+and <i>Polypterus bichir</i>, with the singularly modified
+<i>Calamoichthys</i>. The two former range from east to west, and are
+accompanied by an Osteoglossoid (<i>Heterotis</i>) which has hitherto
+been found in the Nile and on the West Coast only.</p>
+
+<p>Autochthont and limited to this region are the <i>Mormyridæ</i>,
+<i>Pantodontidæ</i>, and <i>Kneriidæ</i>, a singular type,
+somewhat akin to the Loaches. Of Siluroid genera the most
+characteristic are <i>Synodontis</i>, <i>Rhinoglanis</i>, and the
+electric <i>Malapterurus</i>; of Characinoids, <i>Citharinus</i>,
+<i>Alestes</i>, <i>Xenocharax</i>, <i>Hydrocyon</i>,
+<i>Distichodon</i>, <i>Ichthyborus</i>.</p>
+
+<p>The regions with which Africa (like India) has least similarity
+are, again, the North American and Antarctic. Its affinity with the
+Europe-Asiatic region consists only in having received, like this
+latter, a branch of the Cyprinoids, the African Carps and Barbels
+resembling, on the whole, more Indian than Europo-Asiatic forms. Its
+similarity to Australia is limited to the two regions possessing
+Dipnoous and Osteoglossoid types. But its relations to the two other
+regions of the equatorial zone are near and of great interest.</p>
+
+<p>1. Africa has, in common with India, the Siluroid group of
+<i>Clariina</i>, the <i>Silurina</i>, and <i>Bagrina</i>; and more
+especially the small but very natural family of <i>Notopteridæ</i>,
+represented by three species in India, and by two on the <i>west
+coast</i> of Africa. It would be hazardous to state at present in
+which<span class="pagenum" id="Page_232">[232]</span> of the two regions these fishes first made their appearance,
+but the discovery of remains of <i>Notopteridæ</i> and <i>Silurina</i>
+in tertiary deposits of Sumatra points to the Indian region as their
+original home. We can have less doubt about the other fishes common to
+both regions; they are clearly immigrants into Africa from the East,
+and it is a remarkable fact that these immigrants have penetrated
+to the most distant limits of Africa in the west as well as in the
+south,—viz. the <i>Labyrinthici</i>, represented by two genera closely
+allied to the Indian <i>Anabas</i>; the <i>Ophiocephalidæ</i> and
+<i>Mastacembelidæ</i>, a few species of which have penetrated to the
+west coast, singularly enough being absent from the eastern rivers;
+the <i>Ariina</i>, represented by several species, of which one or
+two are identical with Indian, having extended their range along the
+intervening coasts to the east coast of Africa. The Cyprinoids also
+afford an instance of an Indian species ranging into Africa, viz.
+<i>Discognathus lamta</i>, which seems to have crossed at the southern
+extremity of the Red Sea, as it is found in the reservoirs at Aden and
+the hill-streams of the opposite coast-region of Abyssinia.</p>
+
+<p>2. No such direct influx of species and genera has occurred from
+South America into Africa. Yet the affinity of their Freshwater
+fishes is striking. Two of the most natural families of fishes, the
+<i>Chromides</i> and <i>Characinidæ</i>, are peculiar, and (with
+the exception of <i>Etroplus</i>) restricted to them. The African
+and South American Dipnoi are closely allied to each other. The
+<i>Pimelodina</i>, so characteristic of Tropical America, have three
+representatives in Africa, viz., <i>Pimelodus platychir</i>, <i>P.
+balayi</i>, and <i>Auchenoglanis biscutatus</i>; the <i>Doradina</i>
+are another Siluroid group restricted to these two continents.<a id="FNanchor_25" href="#Footnote_25" class="fnanchor">[25]</a>
+Yet, with all these points of close resemblance,<span class="pagenum" id="Page_233">[233]</span> the African and
+South American series are, with the exception of the two species of
+Pimelodus, <i>generically</i> distinct; which shows that the separation
+of the continents must have been of an old date. On the other hand,
+the existence of so many similar forms on both sides of the Atlantic
+affords much support to the supposition that at a former period the
+distance between the present Atlantic continents was much less, and
+that the fishes which have diverged towards the East and West are
+descendants of a common stock which had its home in a region now
+submerged under some intervening part of that ocean. Be this as it
+may, it is evident that the physical conditions of Africa and South
+America have remained unchanged for a considerable period, and are
+still sufficiently alike to preserve the identity of a number of
+peculiar freshwater forms on both sides of the Atlantic. Africa and
+South America are, moreover, the only continents which have produced in
+Freshwater fishes, though in very different families, one of the most
+extraordinary modifications of an organ—the conversion, that is, of
+muscle into an apparatus creating electric force.</p>
+
+<p>C. The boundaries of the <span class="smcap">Tropical American</span>
+(<i>Neotropical</i>) <span class="smcap">Region</span> have been sufficiently indicated
+in the definition of the Equatorial zone. A broad and most irregular
+band of country, in which the South and North American forms are mixed,
+exists in the north; offering some peculiarities which deserve fuller
+attention in the subsequent description of the relations between the
+South and North American faunæ. The following Freshwater fishes inhabit
+this region:—</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="cht">Dipnoi [Australia, Africa]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Lepidosiren paradoxa</i></td>
+    <td class="right">1</td>
+    <td class="ctr">species.</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Polycentridæ</i></td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Chromides [Africa]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Heros</i>, <i>Acara</i>, <i>Cichla</i>, etc.</td>
+    <td class="right">80</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">(<i>Lucifuga</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„)<span class="pagenum" id="Page_234">[234]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht">Siluridæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Hypophthalmina</i></td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Pimelodina [Africa, 2 species]</td>
+    <td class="right">70</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Ariina [Africa, India, Australia, Fuegian]</td>
+    <td class="right">35</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Doradina [Africa]</td>
+    <td class="right">60</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Hypostomatina [India]</td>
+    <td class="right">90</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Aspredinina</i></td>
+    <td class="right">9</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Nematogenyina [Fuegian]—</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Trichomycterina [Fuegian]</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Stegophilina</i></td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Characinidae [Africa]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Erythrinina</i></td>
+    <td class="right">15</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Curimatina</i></td>
+    <td class="right">40</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Anastomatina</i></td>
+    <td class="right">25</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Tetragonopterina</td>
+    <td class="right">80</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Hydrocyonina</td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Crenuchina</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Serrasalmonina</td>
+    <td class="right">35</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">Cyprinodontidæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Carnivoræ [Europe, Asia, N. America, India, Africa]</td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Limnophagæ</i></td>
+    <td class="right">31</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Osteoglossidæ [Africa, India, Australia]</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Gymnotidæ</i></td>
+    <td class="right">20</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="chtb">Symbranchidæ [India]</td>
+    <td class="rightb">1</td>
+    <td class="ctrb">„</td>
+  </tr>
+
+  <tr>
+    <td class="chtbd"></td>
+    <td class="rightbd">672</td>
+    <td class="ctrbd">species.</td>
+  </tr>
+</table>
+
+<p>Out of the 39 families or groups of Freshwater fishes, 9 only are
+represented in the Tropical American region. This may be accounted for
+by the fact that South America is too much isolated from the other
+regions of the Equatorial zone to have received recent additions to
+its fauna. On the other hand, the number of species exceeds that of
+every other region, even of the Indian, with which, in regard to the
+comparative development of families, the Neotropical region shows great
+analogy, as will be seen from the following Table:—</p>
+
+<p><span class="pagenum" id="Page_235">[235]</span></p>
+
+<table class="smaller">
+  <tr>
+    <td class="ctr" colspan="2">INDIAN.</td>
+    <td class="ctr" colspan="2">&emsp;&ensp;NEOTROPICAL.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Siluridæ</td>
+    <td class="right">200 sp.</td>
+    <td class="cht3">Siluridæ</td>
+    <td class="right">276 sp.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Cyprinidæ</td>
+    <td class="right">330 sp.</td>
+    <td class="cht3">Characinidæ</td>
+    <td class="right">226 sp.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Labyrinthici</td>
+    <td class="right">25 sp.</td>
+    <td class="cht3">Chromides</td>
+    <td class="right">80 sp.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Ophiocephalidæ</td>
+    <td class="right">30 sp.</td>
+    <td class="cht3">Cyprinodontidæ</td>
+    <td class="right">60 sp.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Mastacembelidæ</td>
+    <td class="right">10 sp.</td>
+    <td class="cht3">Gymnotidæ</td>
+    <td class="right">20 sp.</td>
+  </tr>
+</table>
+
+<p>In both regions the great number of species is due to the development
+of numerous local forms of two families, the <i>Characinidæ</i> taking
+in the New World the place of the <i>Cyprinidæ</i> of the Old World.
+Thereto are added a few smaller families with a moderately large number
+of species, which, however, is only a fraction of that of the leading
+families, the remainder of the families being represented by a few
+species only. The number of genera within each of the two regions of
+the two principal families is also singularly alike; the Indian region
+having produced about 45 Siluroid and as many Cyprinoid genera, whilst
+the Neotropical region is tenanted by 54 Siluroid and 40 Characinoid
+genera. These points of similarity between the two regions cannot
+be accidental; they indicate that agreement in their physical and
+hydrographical features which in reality exists.</p>
+
+<p>Of Ganoids, we find in Tropical America one species only,
+<i>Lepidosiren paradoxa</i>, accompanied by two Osteoglossoids
+(<i>Osteoglossum bicirrhosum</i> and <i>Arapaima gigas</i>).</p>
+
+<p>Autochthont and limited to this region are the <i>Polycentridæ</i>,
+all the non-African genera of <i>Chromides</i> and <i>Characinidæ</i>;
+of Siluroids, the <i>Hypophthalmina</i>, <i>Aspredinina</i>,
+and <i>Stegophilina</i>, and the majority of <i>Pimelodina</i>,
+<i>Hypostomatina</i>, and <i>Doradina</i>; the herbivorous Cyprinodonts
+or <i>Limnophagæ</i>, and numerous insectivorous Cyprinodonts or
+<i>Carnivoræ</i>; and the <i>Gymnotidæ</i> (Electric eel).</p>
+
+<p>The relations to the other regions are as follows:—</p>
+
+<p>1. The resemblances to the Indian and Tropical Pacific regions partly
+date from remote geological epochs, or are partly<span class="pagenum" id="Page_236">[236]</span> due to that
+similarity of physical conditions to which we have already referred.
+We have again to draw attention to the unexplained presence in South
+America of a representative of a truly Indian type (not found in
+Africa), viz. <i>Symbranchus marmoratus</i>. On the other hand, a
+direct genetic affinity exists between the Neotropical and African
+regions, as has been noticed in the description of the latter, a great
+part of their freshwater fauna consisting of descendants from a common
+stock.</p>
+
+<p>2. A comparison of the specifically Neotropical with the specifically
+North American types shows that no two regions can be more dissimilar.
+It is only in the intervening borderland, and in the large West Indian
+Islands, that the two faunæ mix with each other. We need not enter into
+the details of the physical features of Central America and Mexico—the
+broken ground, the variety of climate (produced by different altitudes)
+within limited districts, the hot and moist alluvial plains surrounding
+the Mexican Gulf, offer a diversity of conditions most favourable to
+the intermixture of the types from the north and the south. But yet
+the exchange of peculiar forms appears to be only beginning; none have
+yet penetrated beyond the debatable ground, and it is evident that the
+land-connection between the two continents is of comparatively recent
+date: a view which is confirmed by the identity of the marine fishes on
+both sides of Central America.</p>
+
+<p>Cuba—and this is the only island in the West Indies which has a
+number of freshwater fishes sufficient for the determination of its
+zoo-geographical relations—is inhabited by several kinds of a perch
+(<i>Centropomus</i>), freshwater mullets, Cyprinodonts, one species
+of Chromid (an <i>Acara</i>), and <i>Symbranchus marmoratus</i>. All
+these fishes are found in Central America, and as they belong to forms
+known to enter brackish water more or less freely, it is evident that
+they have crossed from the mainland of South America or from Central<span class="pagenum" id="Page_237">[237]</span>
+America. But with them there came a remarkable North American type,
+<i>Lepidosteus</i>. <i>Lepidosteus viridis</i>, which is found in the
+United States, has penetrated on the mainland to the Pacific coast
+of Guatemala, where it is common at the mouth of the rivers and in
+brack-water lakes along the coast; it probably crossed into Cuba from
+Florida. A perfectly isolated type of fishes inhabits the subterranean
+waters of the caves of Cuba (two species of <i>Lucifuga</i>). The
+eyes are absent or quite rudimentary, as in most other cave animals.
+Singularly, it belongs to a family (<i>Ophidiidæ</i>), the members
+of which are strictly marine; and its nearest ally is a genus,
+<i>Brotula</i>, the species of which are distributed over the
+Indo-Pacific Ocean, one only occurring in the Caribbean Sea. This type
+must have witnessed all the geological changes which have taken place
+since Cuba rose above the surface of the sea.</p>
+
+<p>A similar mixture of forms of the Tropical and Temperate types of
+Freshwater fishes takes place in the south of South America; its
+details have not yet been so well studied as in the north; but this
+much is evident that, whilst in the East Tropical forms follow the
+Plate river far into the Temperate region, in the West the Temperate
+Fauna finds still a congenial climate in ranges of the Andes, situated
+close to, or even north of, the Tropic.</p>
+
+<p>Like the Indian region, the Tropical American has a peculiar Alpine
+Fauna, the Freshwater fishes of which, however, belong to the
+Siluroids and Cyprinodonts. The former are small, dwarfed forms
+(<i>Arges</i>, <i>Stygogenes</i>, <i>Brontes</i>, <i>Astroblepus</i>,
+<i>Trichomycterus</i>, <i>Eremophilus</i>), and have a perfectly
+naked body, whilst the representatives in the lowlands of, at least,
+the first four genera are mailed. The Alpine Cyprinodonts, on the
+other hand, (<i>Orestias</i>) exceed the usual small size of the
+other members of this family, are covered with thick scales, but
+have lost their ventral fins. Some of these Alpine forms, like
+<i>Trichomycterus</i>, follow the range of the Andes far<span class="pagenum" id="Page_238">[238]</span> into the
+southern temperate region. The majority reach to a height of 15,000
+feet above the level of the sea, and a few are found still higher.</p>
+
+<p>D. The <span class="smcap">Tropical Pacific Region</span> includes all the islands east
+of Wallace’s Line, New Guinea, Australia—with the exception of its
+south-eastern portion,—and all the islands of the Tropical Pacific to
+the Sandwich group. Comparing the area of this region with that of the
+others, we find it to be not only the poorest in point of the number of
+its species generally, but also in that of the possession of peculiar
+forms, as will appear from the following list:—</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="cht">Dipnoi [Neotrop., Africa.]</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Ceratodus</i></td>
+    <td class="right">2</td>
+    <td class="ctr">species.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Percidæ [Cosmopol.]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Lates (calcarifer) [India]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Nannoperca</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Oligorus [New Zealand]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Dules [India]</td>
+    <td class="right">8</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">(<i>Macquaria</i>)</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Labyrinthici—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Anabas (scandens) [India]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Ophiocephalidæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Ophiocephalus (striatus) [India]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Atherinidæ [Brack-water]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Atherinichthys</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Osteoglossidæ [India, Africa, Neotrop.]</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Siluridæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Plotosina [India]</td>
+    <td class="right">9</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Ariina [India, Africa, Neotrop.]</td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Symbranchidæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3b">Monopterus (javanicus) [India]</td>
+    <td class="rightb">1</td>
+    <td class="ctrb">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht10">Total</td>
+    <td class="rightbd">36</td>
+    <td class="ctrbd">species.</td>
+  </tr>
+</table>
+
+<p>The paucity of freshwater fishes is due, in the first place, to the
+arid climate and the deficiency of water in the Australian<span class="pagenum" id="Page_239">[239]</span> continent,
+as well as to the insignificant size of the freshwater courses in
+the smaller islands. Still this cannot be the only cause: the large
+island of Celebes, which, by its mountainous portions, as well as by
+its extensive plains and lowlands, would seem to offer a favourable
+variety of conditions for the development of a freshwater Fauna is,
+as far as has been ascertained, tenanted by seven Freshwater fishes
+only, viz. 2 <i>Arius</i>, 2 <i>Plotosus</i>, 1 <i>Andbas</i>, 1
+<i>Ophiocephalus</i>, 1 <i>Monopterus</i>, all of which are the
+commonest species of the Indian region. New Guinea has not yet been
+explored, but, from the faunæ nearest to this island, we expect its
+freshwater fishes will prove to be equally few in number, and identical
+with those of Celebes and North Australia; a supposition confirmed by
+the few small collections which have reached Europe. Finding, then,
+that even those parts of this region, which are favourable to the
+development of Freshwater fishes, have not produced any distinct forms,
+and that the few species which inhabit them, are unchanged, or but
+slightly modified Indian species, we must conclude that the whole of
+this area has remained geologically isolated from the other regions of
+this zone since the commencement of the existence of Teleostei; and
+that, with the exception of <i>Ceratodus</i> and <i>Osteoglossum</i>,
+the immigration of the other species is of very recent date.</p>
+
+<p>Fossil remains of <i>Ceratodus</i> have been found in Liassic and
+Triassic formations of North America, England, Germany, and India;
+and it is, therefore, a type which was widely spread in the Mesozoic
+epoch. Although it would be rash to conclude that its occupation
+of Australia dates equally far back, for it may have reached that
+continent long afterwards; yet it is evident that, as it is one of the
+most ancient of the existing types, so it is certainly the first of the
+Freshwater fishes which appeared in Australia. <i>Osteoglossum</i>,
+of which no fossil remains yet have been found, is proved by its
+distribution<span class="pagenum" id="Page_240">[240]</span> to be one of the oldest Teleosteous types. There must
+have been a long gap of time before these ancient types were joined
+by the other Teleostei. All of them migrated through the intervening
+parts of the ocean from India. Most of the <i>Plotosina</i>, some of
+the <i>Arii</i>, <i>Dules</i>, and the <i>Atherinichthys</i>, also
+<i>Nannoperca</i> (allied to <i>Apogon</i>), were among the earliest
+arrivals, being sufficiently differentiated to be specifically or even
+generically (<i>Cnidoglanis</i>, <i>Nannoperca</i>) distinguished; but
+some others, like <i>Anabas scandens</i>, <i>Lates calcarifer</i>,
+<i>Dules marginatus</i>, must have reached the Australian continent
+quite recently, for they are indistinguishable from Indian specimens.</p>
+
+<p>In South-western Australia a mingling of the scanty fauna with that of
+the southern temperate parts takes place. <i>Oligorus macquariensis</i>
+(The Murray Cod), which has a congener on the coast of New Zealand,
+ascends high up the Murray river, so that we cannot decide whether
+this Percoid should be located in the Tropical or Temperate part of
+Australia. Several <i>Galaxias</i> also extend to the confines of
+Queensland, and will probably some day be found members of this region.</p>
+
+<p>In the smaller Pacific islands the Freshwater fishes exhibit a
+remarkable sameness: two or three species of <i>Dules</i>, several
+Eels, an Atherine, or some Gobies, Mullets, and other fishes which with
+equal readiness exchange fresh for salt water, and which would at once
+reach and occupy any streams or freshwater lakes that may be formed on
+an island.</p>
+
+<p>The Sandwich Islands are the only group among the smaller islands which
+are tenanted by a Siluroid, a species of <i>Arius</i>, which is closely
+allied to Central American species, and, therefore, probably immigrated
+from Tropical America.</p>
+
+
+<h3>II. <span class="smcap">Northern Zone.</span></h3>
+
+<p>The boundaries of the Northern Zone coincide in the<span class="pagenum" id="Page_241">[241]</span> main with
+the northern limit of the Equatorial Zone; but at three different
+points they overlap the latter, as has been already indicated.
+This happens in, and east of, Syria, where the mixed faunæ of the
+Jordan and the rivers of Mesopotamia demand the inclusion of this
+territory into the Northern Zone as well as the Equatorial; in the
+island of Formosa, where a Salmonoid and several Japanese Cyprinoids
+flourish; and in Central America, where a <i>Lepidosteus</i>, a
+Cyprinoid (<i>Sclerognathus meridionalis</i>), and an Amiurus (<i>A.
+meridionalis</i>) represent the North American fauna in the midst of a
+host of tropical forms.</p>
+
+<p>A separate <i>Arctic</i> Zone does not exist for Freshwater fishes;
+ichthyic life becomes extinct towards the pole as soon as the fresh
+water remains frozen throughout the year, or thaws for a few weeks
+only; and the few fishes which extend into high latitudes, in which
+lakes are open for two or three months in the year, belong to types in
+no wise differing from those of the more temperate south. The highest
+latitude at which fishes have been obtained is 82° lat. N., whence
+the late Arctic Expedition brought back specimens of Charr (<i>Salmo
+arcturus</i> and <i>Salmo naresii</i>).</p>
+
+<p>The ichthyological features of this zone are well marked:
+the Chondrosteous Ganoids or Sturgeons, and the families of
+<i>Salmonidæ</i> and <i>Esocidæ</i> are limited to, and characteristic
+of, it; Cyprinoids flourish with the Salmonoids, both families
+preponderating in numbers over the others, whilst the Siluroids are few
+in number and in variety.</p>
+
+<p>The two regions in which this zone is divided are very closely related
+to one another, and their affinity is not unlike that which obtains
+between the sub-regions of the Southern Zone. The subjoined list
+will show their close agreement with regard to families as well as
+species. Several of the latter are common to both, viz.—<i>Acipenser
+sturio</i>, <i>A. maculatu</i>s, <i>Perca fluviatilis</i>,
+<i>Gastrosteus pungitius</i>, <i>Salmo salar</i>,<span class="pagenum" id="Page_242">[242]</span> <i>Esox lucius</i>,
+<i>Lota vulgaris</i>, <i>Petromyzon marinus</i>, <i>P. fluviatilis</i>,
+and <i>P. branchialis</i>; and all recent investigations have resulted
+in giving additional evidence of the affinity, and not of the diversity
+of the two regions.</p>
+
+<p>In Europe and temperate Asia, as well as in North America, mountain
+ranges elevated beyond the line of perpetual snow would seem to offer
+physical conditions favourable for the development of a distinct
+alpine fauna. But this is not the case, because the difference of
+climate between the mountain districts and the lowlands is much less in
+this zone than in the Equatorial. Consequently the alpine freshwater
+fishes do not essentially differ from those of the plains; they are
+principally Salmonoids; and in Asia, besides, mountain-barbels and
+Loaches. <i>Salmo orientalis</i> was found by Griffith to abound in the
+tributaries of the Bamean river at an altitude of about 11,000 feet.</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="cht"></td>
+    <td class="ctr" colspan="2">Europo-Asiatic.</td>
+    <td class="ctr" colspan="2">N. American.</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Acipenseridæ</i>—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+    <td class="right1"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Acipenser</td>
+    <td class="right">9</td>
+    <td class="ctr">species.</td>
+    <td class="right1">12</td>
+    <td class="ctr">species.</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Scaphirhynchus</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Polyodon</td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Lepidosteidæ</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Amiidæ</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Percina [Cosmopol.]</td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+    <td class="right1">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Grystina [Australia, New Zealand]</td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Centrarchina</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">26</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Aphredoderidæ</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Cottidæ [partly marine]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+    <td class="right1"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Cottus</i></td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+    <td class="right1">8</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Ptyonotus</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Gastrosteidæ</i></td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+    <td class="right1">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Comephoridæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+    <td class="right1">0</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Gadidæ [marine]—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+    <td class="right1"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Lota</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Siluridæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+    <td class="right1"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Silurina [India, Africa]</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+    <td class="right1">0</td>
+    <td class="ctr">„<span class="pagenum" id="Page_243">[243]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Bagrina</td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+    <td class="right1">0</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Amiurina</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+    <td class="right1">17</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Salmonidæ</i></td>
+    <td class="right">90</td>
+    <td class="ctr">„</td>
+    <td class="right1">45</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Percopsidæ</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Esocidæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+    <td class="right1">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Umbridæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Cyprinodontidæ Carnivoræ [India, Africa, Neotrop.]</td>
+    <td class="right">9</td>
+    <td class="ctr">„</td>
+    <td class="right1">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Heteropygii</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Cyprinidæ—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+    <td class="right1"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Catostomina</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+    <td class="right1">25</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Cyprinina [India, Africa]</td>
+    <td class="right">80</td>
+    <td class="ctr">„</td>
+    <td class="right1">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Leuciscina</i></td>
+    <td class="right">60</td>
+    <td class="ctr">„</td>
+    <td class="right1">70</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Rhodeina</i></td>
+    <td class="right">10</td>
+    <td class="ctr">„</td>
+    <td class="right1">0</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Abramidina [India, Africa]</td>
+    <td class="right">44</td>
+    <td class="ctr">„</td>
+    <td class="right1">10</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Cobitidina [India]</td>
+    <td class="right">20</td>
+    <td class="ctr">„</td>
+    <td class="right1">0</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Hyodontidæ</i></td>
+    <td class="right">0</td>
+    <td class="ctr">„</td>
+    <td class="right1">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Petromyzontidæ [Southern Zone]</td>
+    <td class="rightb">4</td>
+    <td class="ctrb">„</td>
+    <td class="right1b">8</td>
+    <td class="ctrb">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"></td>
+    <td class="rightbd">360</td>
+    <td class="ctrbd">species.</td>
+    <td class="right1bd">339</td>
+    <td class="ctrbd">species.</td>
+  </tr>
+</table>
+
+<p>A. <span class="smcap">The Europo-Asiatic (Palæarctic) Region.</span>—Its western and
+southern boundaries coincide with those of the Northern Zone, so that
+only those which divide it from North America have to be indicated.
+Behring’s Strait and the Kamtschatka Sea have been conventionally
+taken as the boundary, but this is shown to be artificial by the fact
+that the animals of both coasts, as far as they are known at present,
+are not sufficiently distinct to be referred to two distinct regions.
+As to the freshwater fishes those of North-western America and of
+Kamtschatka are but imperfectly known, but there can be little doubt
+that the same agreement exists between them as is the case with other
+classes of animals. The Japanese islands exhibit a decided Palæarctic
+fish-fauna, which includes Barbus and Cobitioids, forms strange to the
+North American fauna. A slight influx of tropical forms is perceived in
+the<span class="pagenum" id="Page_244">[244]</span> south of Japan, where two Bagrina (<i>Pseudobagrus aurantiacus</i>
+and <i>Liocassis longirostris</i>) have established themselves for a
+considerable period, for both are peculiar to the island, and have not
+been found elsewhere.</p>
+
+<p>In the east, as well as in the west, the distinction between the
+Europo-Asiatic and North American regions disappears almost entirely
+the farther we advance towards the north. Of four species of the genus
+Salmo known from Iceland, one (<i>S. salar</i>) is common to both
+regions, two are European (<i>S. fario</i> and <i>S. alpinus</i>), and
+one is a peculiarly Icelandic race (<i>S. nivalis</i>). As far as we
+know the Salmonoids of Greenland and Baffin’s Land they are all most
+closely allied to European species, though they may be distinguished as
+local races.</p>
+
+<p>Finally, as we have seen above, the Europo-Asiatic fauna mingles
+with African and Indian forms in Syria, Persia, and Afghanistan.
+<i>Capoëta</i>, a Cyprinoid genus, is characteristic of this district,
+and well represented in the Jordan and rivers of Mesopotamia.</p>
+
+<p>Assuming that the distribution of Cyprinoids has taken its origin from
+the alpine tract of country dividing the Indian and Palæarctic regions,
+we find that this type has found in the temperate region as equally
+favourable conditions for its development as in the tropical. Out of
+the 360 species known to exist in the Palæarctic regions, no less than
+215 are Cyprinoids. In the countries and on the plateaus immediately
+joining the Himalayan ranges those mountain forms which we mentioned
+as peculiar to the Indian Alps abound and extend for a considerable
+distance towards the west and east, mixed with other <i>Cyprinina</i>
+and <i>Cobitidina</i>. The representatives of these two groups are
+more numerous in Central and Eastern Asia than in Europe and the
+northern parts of Asia, where the <i>Leuciscina</i> predominate.
+<i>Abramidina</i> or Breams are more numerous in the south and east
+of Asia, but they spread to the extreme north-western and northern
+limits, to<span class="pagenum" id="Page_245">[245]</span> which the Cyprinoid type reaches. The <i>Rhodeina</i> are
+a small family especially characteristic of the East, but with one or
+two off-shoots in Central Europe. Very significant is the appearance in
+China of a species of the <i>Catostomina</i>, a group otherwise limited
+to North America.</p>
+
+<p>The Cyprinoids, in their dispersal from the south northwards, are
+met from the opposite direction by the Salmonoids. These fishes are,
+without doubt, one of the youngest families of <i>Teleostei</i>, for
+they did not appear before the Pliocene era; they flourished at any
+rate during the glacial period, and, as is testified by the remnants
+which we find in isolated elevated positions, like the Trout of the
+Atlas, of the mountains of Asia-Minor, and of the Hindu Kush, they
+spread to the extreme south of this region. At the present day they are
+most numerously represented in its northern temperate parts; towards
+the south they become scarcer, but increase again in numbers and
+species, wherever a great elevation offers them the snow-fed waters
+which they affect. In the rivers of the Mediterranean Salmonoids are by
+no means scarce, but they prefer the upper courses of those rivers, and
+do not migrate to the sea.</p>
+
+<p>The Pike, Umbra, several species of Perch and Stickleback, are also
+clearly autochthont species of this region. Others belong to marine
+types, and seem to have been retained in fresh water at various
+epochs: thus the freshwater Cottus (Miller’s Thumb); <i>Cottus
+quadricornis</i>, which inhabits lakes of Scandinavia, whilst other
+individuals of the same species are strictly marine; the Burbot
+(<i>Lota vulgaris</i>); and the singular <i>Comephorus</i>, a dwarfed
+and much-changed Gadoid which inhabits the greatest depths of Lake
+Baikal.</p>
+
+<p>Remnants of the Palæichthyic fauna are the <i>Sturgeons</i> and
+<i>Lampreys</i>. The former inhabit in abundance the great rivers of
+Eastern Europe and Asia, periodically ascending them from the sea;
+their southernmost limits are the Yangtse-kiang<span class="pagenum" id="Page_246">[246]</span> in the east, and
+rivers flowing into the Adriatic, Black and Caspian Seas, and Lake
+Aral, towards the centre of this region. None are known to have gone
+beyond the boundaries of the Northern Zone. If the Lampreys are justly
+reckoned among Freshwater fishes, their distribution is unique and
+exceptional. In the Palæarctic region some of the species descend
+periodically to the sea, whilst others remain stationary in the rivers;
+the same has been observed in the Lampreys of North America. They are
+entirely absent in the Equatorial Zone, but reappear in the Temperate
+Zone of the Southern Hemisphere. Many points of the organisation of the
+Cyclostomes indicate that they are a type of great antiquity.</p>
+
+<p>The remaining Palæarctic fishes are clearly immigrants from
+neighbouring regions: thus <i>Silurus</i>, <i>Macrones</i>, and
+<i>Pseudobagrus</i> from the Indian region; <i>Amiurus</i> (and,
+as mentioned above, <i>Catostomus</i>) from North America. The
+Cyprinodonts are restricted to the southern and warmer parts; all
+belong to the carnivorous division. The facility with which these
+fishes accommodate themselves to a sojourn in fresh, brackish, or salt
+water, and even in thermal springs, renders their general distribution
+easily comprehensible, but it is impossible to decide to which region
+they originally belonged; their remains in tertiary deposits round the
+Mediterranean are not rare.</p>
+
+<hr class="tb">
+
+<p><i>B</i>. The boundaries of the <span class="smcap">North American</span> or <span class="smcap">Nearctic
+Region</span> have been sufficiently indicated. The main features and the
+distribution of this fauna are identical with those of the preceding
+region. The proportion of Cyprinoid species to the total number of
+North-American fishes (135:339) appears to be considerably less than in
+the Palæarctic region, but we cannot admit that these figures approach
+the truth, as the Cyprinoids of North America have been much less<span class="pagenum" id="Page_247">[247]</span>
+studied than those of Europe; of many scarcely more than the name is
+known. This also applies in a great measure to the Salmonoids, of which
+only half as many as are found in the Palæarctic region have been
+sufficiently described to be worthy of consideration. North America
+will, without doubt, in the end show as many distinct races as Europe
+and Asia.</p>
+
+<p>Cyprinoids, belonging to genera living as well as extinct, existed in
+North America in the tertiary period. At present, <i>Cyprinina</i>,
+<i>Leuciscina</i>, and <i>Abramidina</i> are well represented, but
+there is no representative of the Old World genus <i>Barbus</i>,
+or of the <i>Cobitidina</i><a id="FNanchor_26" href="#Footnote_26" class="fnanchor">[26]</a>; <i>Rhodeina</i> are also absent.
+On the other hand, a well-marked Cyprinoid type is developed—the
+<i>Catostomina</i>, of which one species has, as it were, returned
+into Asia. Very characteristic is the group of <i>Centrarchina</i>,
+allied to the Perch, of which there are some thirty species; two
+<i>Grystina</i>. Of the Sticklebacks there are as many species
+as in Europe, and of Pike not less than seven species have been
+distinguished. <i>Umbra</i> appears to be as local as in Europe. Some
+very remarkable forms, types of distinct families, though represented
+by one or two species only, complete the number of North American
+autochthont fishes—viz., <i>Aphredoderus</i>, <i>Percopsis</i>,
+<i>Hyodon</i>, and the <i>Heteropygii</i> (<i>Amblyopsis</i> and
+<i>Chologaster</i>). The last are allied to the Cyprinodonts, differing
+from them in some points of the structure of their intestines. The two
+genera are extremely similar, but <i>Chologaster</i>, which is found
+in ditches of the rice-fields of South Carolina, is provided with
+eyes, and lacks the ventral fins. <i>Amblyopsis</i> is the celebrated
+Blind Fish of the Mammoth Cave of Kentucky: colourless, eyeless, with
+rudimentary ventral fins, which may be occasionally entirely absent.</p>
+
+<p><span class="pagenum" id="Page_248">[248]</span></p>
+
+<p>A peculiar feature of the North American Fish Fauna is that it has
+retained, besides the Sturgeons and Lampreys, representatives of two
+Ganoid families, <i>Lepidosteus</i> and <i>Amia</i>. Both these genera
+existed in tertiary times: the former occurs in tertiary deposits of
+Europe as well as North America, whilst fossil remains of <i>Amia</i>
+have been found in the Western Hemisphere only.</p>
+
+<p>It is difficult to account for the presence of the <i>Amiurina</i> in
+North America. They form a well-marked division of the <i>Bagrina</i>,
+which are well represented in Africa and the East Indies, but absent in
+South America; it is evident, therefore, they should not be regarded
+as immigrants from the south, as is the case with the Palæarctic
+Siluroids. Nor, again, has the connection between South and North
+America been established sufficiently long to admit of the supposition
+that these Siluroids could have spread in the interval from the south
+to the northern parts of the continent, for some of the species are
+found as far north as Pine Islands Lake (54° lat. N.)<a id="FNanchor_27" href="#Footnote_27" class="fnanchor">[27]</a></p>
+
+
+<h3>III. <span class="smcap">Southern Zone.</span></h3>
+
+<p>The boundaries of this zone have been indicated in the description of
+the Equatorial Zone; they overlap the southern boundaries of the latter
+in South Australia and South America, but we have not at present the
+means of exactly defining the limits to which southern types extend
+northwards. This zone includes Tasmania with at least a portion of
+South-eastern Australia (<i>Tasmanian sub-region</i>), New Zealand
+and the Auckland Islands (<i>New Zealand sub-region</i>), and Chili,
+Patagonia, Terra del Fuego, and the Falkland Islands (<i>Fuegian
+sub-region</i>). No freshwater fishes are known<span class="pagenum" id="Page_249">[249]</span> from Kerguelen’s Land,
+or from islands beyond 55° lat. S. The southern extremity of Africa has
+to be excluded from this zone so far as Freshwater fishes are concerned.</p>
+
+<p>This zone is, with regard to its extent as well as to the number of
+species, the smallest of the three; yet its ichthyological features
+are well marked; they consist in the presence of two peculiar
+families, each of which is analogous to a northern type, viz.
+the <i>Haplochitonidæ</i>, which represent the <i>Salmonidæ</i>,
+<i>Haplochiton</i> being the analogue of <i>Salmo</i>, and
+<i>Prototroctes</i> that of <i>Coregonus</i>; and the <i>Galaxiidæ</i>,
+which are the Pikes of the Southern Hemisphere.</p>
+
+<p>Although geographically widely separate from each other, the Freshwater
+fishes of the three divisions are nevertheless so closely allied
+that conclusions drawn from this group of animals alone would hardly
+justify us in regarding these divisions as sub-regions. One species of
+<i>Galaxias</i> (<i>G. attenuatus</i>) and the three Lampreys are found
+in all three, or at least two, sub-regions.</p>
+
+<p class="center p1"><i>Freshwater Fishes of the Southern Zone.</i></p>
+
+<table class="smaller">
+  <tr>
+  <td class="cht"></td>
+  <td class="ctr sm">Tasmanian.</td>
+  <td class="ctr sm">N. Zealand.</td>
+  <td class="ctr sm">Fuegian.</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Percichthys</i></td>
+    <td class="right2">...</td>
+    <td class="right3">...</td>
+    <td class="right3">3</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Siluridæ—</td>
+    <td class="right"></td>
+    <td class="right1"></td>
+    <td class="right1"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Diplomystax</i></td>
+    <td class="right2">...</td>
+    <td class="right3">...</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Nematogenys</i></td>
+    <td class="right2">...</td>
+    <td class="right3">...</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht3">Trichomycterina [Neotrop.]</td>
+    <td class="right2">...</td>
+    <td class="right3">...</td>
+    <td class="right3">5</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Gadopsidæ</i></td>
+    <td class="right2">1</td>
+    <td class="right3">...</td>
+    <td class="right3">...</td>
+  </tr>
+
+  <tr>
+    <td class="cht">(<i>Retropinna</i></td>
+    <td class="right2">...</td>
+    <td class="right3">1</td>
+    <td class="right3">...)</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Haplochitonidæ</i></td>
+    <td class="right2">1</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Galaxiidæ</i></td>
+    <td class="right2">6</td>
+    <td class="right3">5</td>
+    <td class="right3">4</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Petromyzontidæ</td>
+    <td class="right2b">3</td>
+    <td class="right3b">1</td>
+    <td class="right3b">3</td>
+  </tr>
+
+  <tr>
+    <td class="cht"></td>
+    <td class="right2bd">11</td>
+    <td class="right3bd">8</td>
+    <td class="right3bd">18</td>
+  </tr>
+</table>
+
+<p>But little remains to be added in explanation of this list;
+<i>Percichthys</i> is in Chili the autochthont form of the
+cosmopolitan<span class="pagenum" id="Page_250">[250]</span> group of <i>Percina</i>. <i>Diplomystax</i>, an Arioid
+fish of Chili, and <i>Nematogenys</i> seem to have crossed the Andes
+from Tropical America at a comparatively early period, as these
+genera are not represented on the eastern side of South America; the
+<i>Trichomycterina</i> occur on both sides of the Andes, which they
+ascend to a considerable height. <i>Retropinna</i> is a true Salmonoid,
+allied to, and representing in the Southern Hemisphere the Northern
+Smelt, <i>Osmerus</i>. In both these genera a part of the specimens
+live in the sea, and ascend rivers periodically to spawn; another part
+remain in rivers and lakes, where they propagate, never descending
+to the sea, this freshwater race being constantly smaller than their
+marine brethren. That this small Teleostean of the Northern Hemisphere
+should reappear, though in a generically modified form, in New Zealand,
+without having spread over other parts of the Southern Zone, is one
+of the most remarkable, and at present inexplicable facts of the
+geographical distribution of freshwater fishes.</p>
+
+  <div class="figcenter" id="fig104" style="max-width: 549px">
+     <img
+    class="p1"   
+    src="images/fig104.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 104.—<i>Haplochiton zebra</i>, Straits of Magelhæn.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_251">[251]</span></p>
+
+<h2 class="smaller">CHAPTER XVIII.<br>
+<span class="subhed">THE FISHES OF THE BRACKISH WATER.</span></h2></div>
+
+<p>On such parts of a coast at which there is a mixture of fresh and salt
+water, either in consequence of some river emptying its water into the
+sea or from an accumulation of land surface water forming lagunes,
+which are in uninterrupted or temporary communication with the sea,
+there flourishes a peculiar brackish water fauna which is characterised
+by the presence of fishes found sometimes in sea-, sometimes in pure
+freshwater.</p>
+
+<p>This fauna can be rather sharply defined if a limited district only
+is taken into consideration; thus, the species of the brackish water
+fauna of Great Britain, the Pacific coast of Central America, of
+the larger East India Islands, etc., can be enumerated without much
+hesitation. But difficulties arise when we attempt to generalise in the
+enumeration of the forms referable to the brackish water fauna; because
+the genera and families enumerated include certain species and genera
+which have habituated themselves exclusively either to a freshwater or
+marine existence; and, besides, because a species of fish may be at
+one locality an inhabitant of brackish water, at another of the sea,
+and at a third of fresh water. The circumstance that these fishes can
+live in sea and fresh water has enabled them to spread readily over the
+globe, a few only being limited to particular regions; therefore, for
+the purposes of dividing the earth’s surface into natural zoological
+regions the brackish water forms are useless. The following fishes may
+be referred to this Fauna:—</p>
+
+<p><span class="pagenum" id="Page_252">[252]</span></p>
+
+<p>1. Species of <i>Rajidæ</i> (<i>Raja</i>, <i>Trygon</i>) prefer the
+mouths of rivers, probably because the muddy or sandy bottom offers the
+most suitable conditions for fishes which can feed on the bottom only;
+such brackish water species belong chiefly to the Equatorial Zone, some
+having taken up their abode entirely in fresh water (South American
+Trygons).</p>
+
+<p>2. <i>Ambassis</i>, a Percoid genus, consisting of numerous small
+species, inhabiting the shores of the tropical parts of the Indian
+Ocean and the coasts of Tropical Australia. Many species enter, and all
+seek the neighbourhood of, fresh water; hence they disappear in the
+islands of the Pacific, and are scarce in the Red Sea.</p>
+
+<p>3. <i>Therapon</i>, with the same distribution as the former.</p>
+
+<p>4. Numerous <i>Sciænidæ</i> of the Equatorial Zone.</p>
+
+<p>5. The <i>Polynemidæ</i>, chiefly inhabitants of brackish water of the
+Equatorial Zone, most developed in the Indian region, and scarce in the
+Tropical Pacific.</p>
+
+<p>6. Numerous species of <i>Caranx</i> (or Horse Mackerels) of the
+Equatorial Zone.</p>
+
+<p>7. Nearly all species of <i>Gastrosteus</i> enter brackish water, <i>G.
+spinachia</i> being almost exclusively confined to it: Northern Zone.</p>
+
+<p>8. The most important genera of the Gobies (<i>Gobiina</i>):
+<i>Gobius</i> (nearly cosmopolitan), <i>Sicydium</i>,
+<i>Boleophthalmus</i>, <i>Periophthalmus</i>, <i>Eleotris</i>
+(equatorial). Many of the species are entirely confined to fresh water.</p>
+
+<p>9. The <i>Amblyopina</i>, similar to the Gobies, but with more
+elongated body: Tropical Indo-Pacific.</p>
+
+<p>10. The <i>Trypauchenina</i>: Coasts of the Indian region.</p>
+
+<p>11. Many species of <i>Blennius</i>, of which several are found far
+inland in fresh waters—for instance in North Italy, in the Lake of
+Galilee, in the eastern parts of Asia Minor.</p>
+
+<p>12. The majority of <i>Atherinidæ</i>, and</p>
+
+<p><span class="pagenum" id="Page_253">[253]</span></p>
+
+<p>13. The <i>Mugilidæ</i>: both families being most numerous and abundant
+in brackish water, and almost cosmopolitan.</p>
+
+<p>14. Many <i>Pleuronectidæ</i> prefer the mouths of rivers for the
+same reason as the Rays; some ascend rivers, as the Flounder,
+<i>Cynoglossus</i>, etc.</p>
+
+<p>15. Several <i>Siluridæ</i>, as especially the genera <i>Plotosus</i>,
+<i>Cnidoglanis</i>, <i>Arius</i>, which attain their greatest
+development in brackish water.</p>
+
+<p>16. The <i>Cyprinodontidæ</i> are frequently found in brackish water.</p>
+
+<p>17. Species of <i>Clupea</i>, some of which ascend rivers, and become
+acclimatized in fresh water, as <i>Clupea finta</i>, which has
+established itself in the lakes of northern Italy.</p>
+
+<p>18. <i>Chatoessus</i>, a genus of Clupeoid fishes of the Equatorial
+Zone, of which some species have spread into the Northern Zone.</p>
+
+<p>19. <i>Megalops</i>: Equatorial Zone.</p>
+
+<p>20. <i>Anguilla.</i> The distribution, no less than the mode of
+propagation, and the habits generally, of the so-called Freshwater-eels
+still present us with many difficult problems. As far as we know
+at present their birthplace seems to be the coast in the immediate
+neighbourhood of the mouths of rivers. They are much more frequently
+found in fresh water than in brackish water, but the distribution of
+some species proves that they at times migrate by sea as well as by
+land and river. Thus <i>Anguilla mauritiana</i> is found in almost
+all the fresh and brackish waters of the islands of the Tropical
+Indian Ocean and Western Pacific, from the Comoros to the South Sea;
+<i>Anguilla vulgaris</i> is spread over temperate Europe (exclusive
+of the system of the Danube, the Black and Caspian Seas), in the
+Mediterranean district (including the Nile and rivers of Syria), and
+on the Atlantic coast of North America; <i>Anguilla bostoniensis</i>,
+in Eastern North America, China, and Japan; <i>Anguilla
+lati</i><i>rostris</i>,<span class="pagenum" id="Page_254">[254]</span> in Temperate Europe, the whole Mediterranean
+district, the West Indies, China, and New Zealand. The other more local
+species are found, in addition to localities already mentioned, on the
+East Coast of Africa, South Africa, on the continent of India, various
+East Indian Islands, Australia, Tasmania, Auckland Islands; but none
+have ever been found in South America, the West Coast of North America,
+and the West Coast of Africa: surely one of the most striking instances
+of irregular geographical distribution.</p>
+
+<p>21. Numerous <i>Syngnathidæ</i> have established themselves in the
+Northern Zone as well as in the Equatorial, in the vegetation which
+flourishes in brackish water.</p>
+
+<p>This list could be considerably increased if an enumeration of species,
+especially of certain localities, were attempted; but this is more a
+subject of local interest, and would carry us beyond the scope of a
+general account of the distribution of Fishes.</p>
+
+  <div class="figcenter" id="fig105" style="max-width: 266px">
+     <img
+    class="p1"   
+    src="images/fig105.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 105.—<i>Mugil octo-radiatus.</i></p>
+  </div>
+
+  <div class="figcenter" id="fig106" style="max-width: 233px">
+     <img
+    class="p1"   
+    src="images/fig106.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 106.—<i>Mugil auratus.</i></p>
+  </div>
+
+  <div class="figcenter" id="fig107" style="max-width: 272px">
+     <img
+    class="p1"   
+    src="images/fig107.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 107.—<i>Mugil septentrionalis.</i></p>
+     <p class="p0 center smaller">Heads of Grey Mullets, fishes of Brackish water.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_255">[255]</span></p>
+
+<h2 class="smaller">CHAPTER XIX.<br>
+<span class="subhed">THE DISTRIBUTION OF MARINE FISHES.</span></h2></div>
+
+<p>Marine fishes fall, with regard to their mode of life and distribution,
+into three distinct categories:—</p>
+
+<p>1. <i>Shore Fishes</i>—That is, fishes which inhabit chiefly parts
+of the sea in the immediate neighbourhood of land either actually
+raised above, or at least but little submerged below, the surface of
+the water. They do not descend to any great depth,—very few to 300
+fathoms, and the majority live close to the surface. The distribution
+of these fishes is determined not only by the temperature of the
+surface water but also by the nature of the adjacent land, and its
+animal and vegetable products; some of these fishes being confined to
+flat coasts with soft or sandy bottoms, others to rocky and fissured
+coasts, others to living coral formations. If it were not for the
+frequent mechanical and involuntary removals to which these fishes
+are exposed, their distribution within certain limits, as it no doubt
+originally existed, would resemble still more that of freshwater fishes
+than we find it actually does at the present period.</p>
+
+<p>2. <i>Pelagic Fishes</i>—that is, fishes which inhabit the surface
+and uppermost strata of the open ocean, which approach the shores only
+accidentally, or occasionally (in search of prey), or periodically
+(for the purpose of spawning). The majority spawn in the open sea,
+their ova and young being always found at great distance from the
+shore. With regard to their distribution, they are still subject to
+the influences of light and the temperature of the surface water; but
+they are<span class="pagenum" id="Page_256">[256]</span> independent of the variable local conditions which tie the
+shore fish to its original home, and therefore roam freely over a space
+which would take a freshwater or shore fish thousands of years to cover
+in its gradual dispersal. Such as are devoid of rapidity of motion
+are dispersed over similarly large areas by the oceanic currents,
+more slowly than, but as surely as, the strong swimmers. Therefore,
+an accurate definition of their distribution within certain areas
+equivalent to the terrestrial regions is much less feasible than in the
+case of shore fishes.</p>
+
+<p>3. <i>Deep-sea Fishes</i>—that is, fishes which inhabit such depths
+of the ocean as to be but little or not influenced by light or the
+surface temperature; and which, by their organisation are prevented
+from reaching the surface stratum in a healthy condition. Living almost
+under identical tellurian conditions, the same type, the same species,
+may inhabit an abyssal depth under the equator as well as one near the
+arctic or antarctic circle; and all we know of these fishes points to
+the conclusion that no separate horizontal regions can be distinguished
+in the abyssal fauna, and that no division into bathymetrical strata
+can be attempted on the base of generic much less of family characters.</p>
+
+<p>It must not be imagined that these three categories are more sharply
+defined than Freshwater and Marine Fishes. They gradually pass into
+each other, and there are numerous fishes about which uncertainty
+exists whether they should be placed in the Shore or Pelagic series, or
+in the Pelagic or Deep-sea series; nay, many facts favour the view that
+changes in the mode of life and distribution of fishes are still in
+progress.</p>
+
+<p>The change in habitat of numerous fishes is regulated by the
+distribution of their favourite food. At certain seasons the surface
+of the sea in the vicinity of land swarms with mollusks, larval
+Crustaceans, Medusæ, attracting shoals of<span class="pagenum" id="Page_257">[257]</span> fishes from the open ocean
+to the shores; and these are again pursued by fishes of larger size and
+predacious habits, so that all these fishes might be included, with
+equal propriety, in the littoral or pelagic series. However, species
+which are known to normally spawn in the open ocean must be always
+referred to the latter division.</p>
+
+<p>Chondropterygii, Acanthopterygii, Anacanths, Myxinoids, and
+Pharyngobranchii furnish the principal contingents to the Marine Fauna;
+whilst the majority of Malacopterygians, the Ganoids, and Cyclostomes
+are Freshwater Fishes.</p>
+
+
+<h3>I.—<span class="smcap">Distribution of Shore Fishes.</span></h3>
+
+<p class="center">The principal types of Shore-fishes are the following:—</p>
+
+<table class="smaller" style="max-width: 50em">
+  <tr>
+    <td class="cht">CHONDROPTERYGII—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3 smcap">Holocephala</td>
+    <td class="right">4</td>
+    <td class="ctr">species</td>
+  </tr>
+
+  <tr>
+    <td class="cht3 smcap">Plagiostomata—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Carchariidæ</i> (part.)</td>
+    <td class="right">12</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Scylliidæ</i></td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Cestraciontidæ</i></td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Spinacidæ</i> (part.)</td>
+    <td class="right">8</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Rhinidæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Pristiophoridæ</i></td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Pristidæ</i></td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Rhinobatidæ</i></td>
+    <td class="right">14</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Torpedinidæ</i></td>
+    <td class="right">15</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Rajidæ</i></td>
+    <td class="right">34</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Trygonidæ</i></td>
+    <td class="right">47</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">ACANTHOPTERYGII—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Percidæ</i> (part. incl. Pristipomatidæ)</td>
+    <td class="right">625</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Mullidæ</i></td>
+    <td class="right">35</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Sparidæ</i></td>
+    <td class="right">130</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Squamipinnes</i></td>
+    <td class="right">130</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Cirrhitidæ</i></td>
+    <td class="right">40</td>
+    <td class="ctr">„<span class="pagenum" id="Page_258">[258]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Heterolepidina</i></td>
+    <td class="right">12</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Scorpænidæ</i></td>
+    <td class="right">120</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Cottiæ</i> (part.)</td>
+    <td class="right">100</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Cataphracti</i> (part.)</td>
+    <td class="right">20</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Trachinidæ</i></td>
+    <td class="right">100</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Sciænidæ</i></td>
+    <td class="right">100</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Sphyrænidæ</i></td>
+    <td class="right">15</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Trichiuridæ</i></td>
+    <td class="right">17</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Elacate</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Nomeidæ</i> (part.)</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Cyttidæ</i></td>
+    <td class="right">8</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Stromateus</i></td>
+    <td class="right">9</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Mene</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Carangidæ</i> (part.)</td>
+    <td class="right">130</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Kurtidæ</i></td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Gobiodon</i></td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Callionymina</i></td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Discoboli</i></td>
+    <td class="right">11</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Batrachidæ</i></td>
+    <td class="right">14</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Pediculati</i> (part.)</td>
+    <td class="right">11</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Blenniidæ</i></td>
+    <td class="right">90</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Acanthoclinidæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Teuthididæ</i></td>
+    <td class="right">30</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Acronuridæ</i></td>
+    <td class="right">60</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Hoplognathidæ</i></td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Malacanthidæ</i></td>
+    <td class="right">3</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Plesiopina</i></td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Trichonotidæ</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Cepolidæ</i></td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Gobiesocidæ</i></td>
+    <td class="right">21</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Psychrolutidæ</i></td>
+    <td class="right">2</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Centriscidæ</i></td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht5"><i>Fistulariidæ</i></td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8 smcap">Acanthopterygii Pharyngognathi—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Pomacentridæ</i></td>
+    <td class="right">150</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Labridæ</i></td>
+    <td class="right">400</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Embiotocidæ</i></td>
+    <td class="right">17</td>
+    <td class="ctr">„<span class="pagenum" id="Page_259">[259]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht8 smcap">Anacanthini—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Gadopsidæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Lycodidæ</i></td>
+    <td class="right">15</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Gadidæ</i> (part.)</td>
+    <td class="right">50</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Ophidiidæ</i> (part.)</td>
+    <td class="right">40</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Pleuronectidæ</i></td>
+    <td class="right">160</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8 smcap">Physostomi—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Saurina</i> (part.)</td>
+    <td class="right">16</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Salmonidæ</i> (part.)</td>
+    <td class="right">7</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Clupeidæ</i> (part.)</td>
+    <td class="right">130</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Chirocentridæ</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Chilobranchus</i></td>
+    <td class="right">1</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Murænidæ</i> (part.)</td>
+    <td class="right">200</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Pegasidæ</i></td>
+    <td class="right">4</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8 smcap">Lophobranchii</td>
+    <td class="right">120</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8 smcap">Plectognathi—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Sclerodermi</i></td>
+    <td class="right">95</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"><i>Gymnodontes</i></td>
+    <td class="right">83</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">CYCLOSTOMATA—</td>
+    <td class="right"></td>
+    <td class="ctr"></td>
+  </tr>
+
+  <tr>
+    <td class="cht3 smcap">Myxinidæ</td>
+    <td class="right">5</td>
+    <td class="ctr">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht8">LEPTOCARDII</td>
+    <td class="rightb">2</td>
+    <td class="ctrb">„</td>
+  </tr>
+
+  <tr>
+    <td class="cht3"></td>
+    <td class="rightbd">3587</td>
+    <td class="ctrbd">species.</td>
+  </tr>
+</table>
+
+<p>These types of Shore fishes are divided among the following oceanic
+areæ:—</p>
+
+<ul class="smaller">
+  <li>&emsp;I. The Arctic Ocean.</li>
+  <li class="p1">&ensp;II. The Northern Temperate Zone.</li>
+  <li class="i1 p1">A. The Temperate North Atlantic.</li>
+  <li class="i2">1. The British district.</li>
+  <li class="i2">2. The Mediterranean district.</li>
+  <li class="i2">3. The North American district.</li>
+  <li class="i1 p1">B. The Temperate North Pacific.</li>
+  <li class="i2">1. The Kamtschatkan district.</li>
+  <li class="i2">2. The Japanese district.</li>
+  <li class="i2">3. The Californian district.<span class="pagenum" id="Page_260">[260]</span></li>
+  <li class="p1">III. The Equatorial Zone.</li>
+  <li class="i1 p1">A. The Tropical Atlantic.</li>
+  <li class="i1">B. The Tropical Indo-Pacific.</li>
+  <li class="i1">C. The Pacific Coast of Tropical America.</li>
+  <li class="i2">1. The Central American district.</li>
+  <li class="i2">2. The Galapagoes district.</li>
+  <li class="i2">3. The Peruvian district.</li>
+  <li class="p1">&ensp;IV. The Southern Temperate Zone.</li>
+  <li class="i2">1. The Cape of Good Hope district.</li>
+  <li class="i2">2. The South Australian district.</li>
+  <li class="i2">3. The Chilian district.</li>
+  <li class="i2">4. The Patagonian district.</li>
+  <li class="p1">&emsp;V. The Antarctic Ocean.</li>
+</ul>
+
+<p>As with freshwater fishes, the main divisions of the Shore-fish faunæ
+are determined by their distance from the equator, the equatorial
+zone of the Freshwater series corresponding entirely to that of
+the Shore-fish series. But as Marine fishes extend farther towards
+the Poles than Freshwater fishes, and as the polar types are more
+specialised, a distinct Arctic and Antarctic fauna may be separated
+from the faunæ of the temperate zones. The two subdivisions of the
+Northern temperate zone in the Freshwater series are quite analogous
+to the corresponding divisions in the Coast series. In the Southern
+Hemisphere the Shore-fishes of the extremity of Africa form a separate
+district of the temperate zone, whilst the Freshwater fishes of
+South Africa were found to be tropical types. The Marine series of
+the Southern temperate zone is also much more diversified than the
+Freshwater series, and admits of further subdivision, which, although
+in some degree indicated in the Freshwater series, does not entirely
+correspond to that proposed for the latter.</p>
+
+<p><span class="pagenum" id="Page_261">[261]</span></p>
+
+
+<h3>I. <span class="smcap">Shore Fishes of the Arctic Ocean.</span></h3>
+
+<p>The Shore fishes clearly prove a continuity of the Arctic circumpolar
+fauna, as the southern limit of which we may indicate the southern
+extremity of Greenland and the Aleutian Archipelago, or 60° of lat. N.</p>
+
+<p>Towards the North, fishes become less in variety of species and fewer
+in number of individuals, and only very few genera are restricted to
+this fauna.</p>
+
+<p>The highest latitude at which Shore fishes have been observed is 83°
+N. lat. The late Arctic Expedition collected at and near that latitude
+specimens of <i>Cottus quadricornis</i>, <i>Icelus hamatus</i>,
+<i>Cyclopterus spinosus</i>, <i>Liparis fabricii</i>, <i>Gymnelis
+viridis</i>, and <i>Gadus fabricii</i>. This number probably would have
+been larger if the difficulties of collecting fishes in those high
+latitudes were not almost insuperable for the greater part of the year.</p>
+
+<p>As far as we know, the fishes north and south of Behring’s Straits
+belong to the same generic or family types as those of the
+corresponding latitudes of the Eastern Hemisphere, though the majority
+are specifically distinct. But the information we possess of the fishes
+of the northernmost extremity of the Pacific is extremely scanty and
+vague. Farther south, whence now and then a collection reaches Europe,
+we meet with some European species, as the Herring, Halibut, Hake.</p>
+
+<p>The Chondropterygians are very scarce, and it is doubtful whether
+another Chondropterygian, beside the pelagic <i>Læmargus</i> or
+Greenland Shark, crosses the Arctic circle. In the more temperate
+latitudes of South Greenland, Iceland, and Northern Scandinavia,
+<i>Acanthias</i>, <i>Centroscyllium</i>, and a species of <i>Raja</i>,
+also <i>Chimæra</i>, are met with.</p>
+
+<p>Of Acanthopterygians the families of <i>Cottidæ</i>,
+<i>Cataphracti</i>, <i>Discoboli</i>, and <i>Blenniidæ</i> are
+well represented, and several of the<span class="pagenum" id="Page_262">[262]</span> genera are characteristic
+of the Arctic fauna: marine species of <i>Cottus</i>;
+<i>Centridermichthys</i>, <i>Icelus</i>, <i>Triglops</i>;
+<i>Agonus</i>, <i>Aspidophoroides</i>; <i>Anarrhichas</i>,
+<i>Centronotus</i>, <i>Stichæus</i>; <i>Cyclopterus</i> and
+<i>Liparis</i>. Two species of <i>Sebastes</i> are rather common.</p>
+
+<p>Characteristic is also the development of Gadoid fishes, of which
+some thirteen species, belonging to <i>Gadus</i>, <i>Merluccius</i>,
+and <i>Molva</i>, form one of the principal articles of food to
+the inhabitants of the coasts of the Arctic Ocean. The Blennioid
+Anacanthini or <i>Lycodidæ</i>, are limited to the Arctic and Antarctic
+coasts. <i>Ammodytes</i> and a few Flat-fishes (<i>Hippoglossoides</i>
+and <i>Pleuronectes</i>) are common in the more temperate parts.</p>
+
+<p>Labroids only exceptionally penetrate so far towards the north.</p>
+
+<p>Physostomes are very scarce, and represented only by a few species
+of <i>Clupea</i> and by <i>Mallotus</i>; the latter is an ancient
+inhabitant of the Greenland coasts, fossil remains, indistinguishable
+from the species of the present day, being frequently found in nodules
+of clay of comparatively recent formation.</p>
+
+<p>The Arctic climate is still less favourable to the existence of
+Lophobranchs, only a few <i>Syngnathus</i> and <i>Nerophis</i> being
+present in the more southern latitudes, to which they have been carried
+by oceanic currents from their more congenial home in the south.
+Scleroderms and Plectognaths are entirely absent.</p>
+
+<p>The Gadoids are accompanied by <i>Myxine</i>, which parasitically
+thrives in them.</p>
+
+
+<h3>II. <span class="smcap">The Northern Temperate Zone.</span></h3>
+
+
+<h4>A. <i>Shore Fishes of the Temperate North Atlantic</i>.</h4>
+
+<p>This part of the fauna may be subdivided into three districts:—</p>
+
+<p><span class="pagenum" id="Page_263">[263]</span></p>
+
+<p>1. The fishes of the north-eastern shores, viz. of the British
+islands, of Scandinavia so far as it is not included in the Arctic
+fauna, and of the continent of Europe southwards to about 40° of lat.
+N.—<i>British</i> district.</p>
+
+<p>2. The fishes of the Mediterranean shores and of the adjoining shores
+of the Atlantic, including the Azores, Madeira, and the Canary
+Islands—<i>Mediterranean</i> district.</p>
+
+<p>3. The fishes of the western shores, from 60° lat. N. to about 30° lat.
+N.—the <i>North American</i> district.</p>
+
+<p class="p1">1. The <i>British</i> district shows scarcely any marked distinctive
+features; the character of its fauna is simply intermediate between
+that of the Arctic Ocean and the Mediterranean district; truly Arctic
+forms disappear, while such as are also found in the Mediterranean make
+their appearance. Also with regard to the abundance of individuals
+and variety of fishes this district forms a transition from the north
+towards the south.</p>
+
+<p>Besides the few Arctic Chondropterygians, all of which extend into
+this district, the small shore Dog-fishes are well represented
+(<i>Mustelus</i>, <i>Galeus</i>, <i>Scyllium</i>, <i>Pristiurus</i>);
+the ubiquitous Rhina or Monk-fish is common; of Rays, <i>Raja</i>
+predominates in a variety of species over <i>Torpedo</i> and
+<i>Trygon</i>, which are still scarce.</p>
+
+<p>Of Acanthopterygians, <i>Centridermichthys</i>, <i>Icelus</i>,
+<i>Triglops</i>, and <i>Aspidophoroides</i>, do not extend from the
+north into this district; and <i>Cottus</i>, <i>Anarrhichas</i>,
+<i>Centronotus</i>, <i>Stichæus</i>, the <i>Discoboli</i> disappear
+within its limits. Nearly all the remainder are genera which are
+also found in the Mediterranean districts. The following are
+the principal forms, and known to propagate on these shores:
+<i>Labrax</i>; <i>Serranus</i>, <i>Polyprion</i>, <i>Dentex</i>;
+<i>Mullus</i>; <i>Cantharus</i>, <i>Pagrus</i>, <i>Pagellus</i>;
+<i>Sebastes</i>; <i>Cottus</i>, <i>Trigla</i>, <i>Agonus</i>;
+<i>Trachinus</i>; <i>Sciæna</i> (?); <i>Zeus</i>; <i>Trachurus</i>,
+<i>Capros</i>; <i>Callionymus</i>; <i>Discoboli</i>; <i>Lophius</i>;
+<i>Anarrhichas</i>, <i>Centronotus</i>, <i>Stich</i><i>æus</i>;<span class="pagenum" id="Page_264">[264]</span>
+<i>Blenniops</i>, <i>Zoarces</i> (not in Mediterranean); <i>Cepola</i>;
+<i>Lepadogaster</i>.</p>
+
+<p>Of the Anacanthini the Gadoids are as numerous as in the Arctic
+Ocean, most being common to both districts; they are represented by
+<i>Gadus</i>, <i>Gadiculus</i>, <i>Merluccius</i>, <i>Phycis</i>,
+<i>Molva</i>, <i>Motella</i>, <i>Raniceps</i>, and <i>Brosmius</i>;
+but, whilst the majority show their northern origin by not extending
+into the Mediterranean, <i>Ammodytes</i> and most <i>Pleuronectidæ</i>
+prove themselves to be the more southern representatives of this
+order. In the British district we find <i>Hippoglossus</i>,
+<i>Hippoglossoides</i>, <i>Rhombus</i>, <i>Phrynorhombus</i>,
+<i>Pleuronectes</i>, <i>Solea</i>, and only the two first are not met
+with in the Mediterranean.</p>
+
+<p>Labroids are common; with the exception of the North American
+<i>Tautoga</i>, all the other genera are met with.</p>
+
+<p>Physostomes are not well represented, viz. by one species of
+<i>Osmerus</i>, one of <i>Engraulis</i>, one of <i>Conger</i>, and
+about five of <i>Clupea</i>.</p>
+
+<p><i>Syngnathus</i> and <i>Nerophis</i> become more common as we proceed
+southwards; but the existence of Scleroderms and Plectognaths is
+indicated by single individuals only, stragglers from their southern
+home, and unable to establish themselves in a climate ungenial to them.</p>
+
+<p>The Gadoids are accompanied by <i>Myxine</i>; and <i>Branchiostoma</i>
+may be found in all suitable localities.</p>
+
+<p class="p1">2. The <i>Mediterranean</i> district is distinguished by a great
+variety of forms; yet, with the exception of a few genera established
+for single species, none of the forms can be considered peculiar to
+it; and even that small number of peculiar genera is more and more
+diminished as our knowledge of the distribution of fishes advances.
+Some genera are identical with those found on the western coasts of the
+Atlantic and in the West Indies; but a most remarkable and unexpected
+affinity obtains with another very distant<span class="pagenum" id="Page_265">[265]</span> fauna, viz. that of
+Japan. The number of genera common to the Mediterranean district and
+the Japanese coasts is larger than that of the genera common to the
+Mediterranean and the opposite American coasts.</p>
+
+<p>The Chondropterygians found in the British district continue in the
+Mediterranean, their number being increased by <i>Centrina</i>,
+<i>Spinax</i>, <i>Pteroplatea</i>, and some species of
+<i>Rhinobatus</i>, a genus more numerously represented in the Tropics.
+<i>Torpedo</i> and <i>Trygon</i> are common.</p>
+
+<p>The greatest variety belong to the Acanthopterygians, as will be
+seen from the following list:—<i>Labrax</i>; <i>Anthias</i>,
+<i>Serranus</i>, <i>Polyprion</i>, <i>Apogon</i>, <i>Pomatomus</i>,
+<i>Pristipoma</i>, <i>Diagramma</i> (an Indian genus with two
+Mediterranean species, and otherwise not represented in the
+Atlantic), <i>Dentex</i>, <i>Mæna</i>, <i>Smaris</i>; <i>Mullus</i>;
+<i>Cantharus</i>, <i>Box</i>, <i>Scatharxs</i>, <i>Oblata</i>,
+<i>Sargus</i>, <i>Pagrus</i>, <i>Pagellus</i>, <i>Chrysophrys</i>;
+<i>Sebastes</i>, <i>Scorpæna</i>; <i>Hoplostethus</i>, <i>Beryx</i>,
+<i>Polymixia</i>; <i>Trigla</i>, <i>Lepidotrigla</i>, <i>Agonus</i>,
+<i>Peristethus</i>; <i>Trachinus</i>, <i>Uranoscopus</i>;
+<i>Umbrina</i>, <i>Sciæna</i>; <i>Sphyræna</i>; <i>Aphanopus</i>,
+<i>Lepidopus</i>, <i>Nesiarchus</i>, <i>Trichiurus</i>,
+<i>Thyrsites</i>; <i>Cubiceps</i>; <i>Zeus</i>, <i>Cyttus</i>;
+<i>Stromateus</i>; <i>Trachurus</i>, <i>Caranx</i>, <i>Capros</i>,
+<i>Diretmus</i>, <i>Antigonia</i>; <i>Callionymus</i>;
+<i>Batrachus</i>; <i>Lophius</i>; <i>Cristiceps</i>,
+<i>Tripterygium</i>; <i>Cepola</i>; <i>Lepadogaster</i>;
+<i>Centriscus</i>; <i>Notacanthus</i>.</p>
+
+<p>The <i>Labridæ</i> are as common as, or even more so than, in the
+British district, and represented by the same genera. But, besides,
+some other Pharyngognaths, properly belonging to the Tropical Atlantic,
+have fully established themselves, though only by a few species,
+viz. <i>Glyphidodon</i> and <i>Heliastes</i>; <i>Cossyphus</i>,
+<i>Novacula</i>, <i>Julis</i>, <i>Coris</i>, and <i>Scarus</i>.</p>
+
+<p>The Gadoids show a marked decrease of development; and the species
+of <i>Gadus</i>, <i>Gadiculus</i>, <i>Mora</i>, <i>Strinsia</i>,
+<i>Phycis</i>, and <i>Molva</i>, which are peculiar to the
+Mediterranean, seem to inhabit rather the colder water of moderate
+depths, than the surface near the shore. <i>Motella</i>, however,
+proves to be a true<span class="pagenum" id="Page_266">[266]</span> Shore fish also in the Mediterranean, at least
+in its adult state. <i>Ophidium</i> and <i>Fierasfer</i> appear
+now besides <i>Ammodytes</i>. As the Gadoids decrease, so the
+<i>Pleuronectidæ</i> increase, the genera of the Mediterranean district
+being <i>Rhombus</i>, <i>Phrynorhombus</i>, <i>Arnoglossus</i>,
+<i>Citharus</i>, <i>Rhomboidichthys</i>, <i>Pleuronectes</i> (a
+northern genus not extending farther southwards), <i>Solea</i>,
+<i>Synaptura</i>, and <i>Ammopleurops</i>.</p>
+
+<p>The variety of Physostomes is small; the following only being
+superadded to those of the British district:—<i>Saurus</i> (a tropical
+genus), <i>Aulopus</i>; <i>Congromuræna</i>, <i>Heteroconger</i>,
+<i>Myrus</i>, <i>Ophichthys</i>, <i>Muræna</i>.</p>
+
+<p>The Lophobranchs are more numerous in species and individuals
+than in the British district; and, besides <i>Syngnathus</i> and
+<i>Nerophis</i>, several species of <i>Hippocampus</i> are common. Also
+a few species of <i>Balistes</i> occur.</p>
+
+<p><i>Myxine</i> is lost in this district; whilst <i>Branchiostoma</i> is
+abundant.</p>
+
+<p class="p1">3. The shore fishes of the <i>North American</i> district consist, as
+on the eastern coasts of the North Atlantic, of northern and southern
+elements; but they are still more mixed with each other than on the
+European coasts, so that a boundary line cannot be drawn between
+them. The affinity to the fauna of the eastern shores is great, but
+almost entirely limited to the genera composing the fauna of the
+British district. British genera not found on the American coasts
+are—<i>Galeus</i>, <i>Scyllium</i>, <i>Chimæra</i>, <i>Mullus</i>,
+<i>Pagellus</i>, <i>Trigla</i>, <i>Trachinus</i>, <i>Zeus</i>,
+<i>Callionymus</i>. The southern elements of North America are
+rather derived from the West Indies, and have no special affinity to
+Mediterranean forms; very few of the non-British Mediterranean forms
+extend across the Atlantic; instead of a Mediterranean we find a West
+Indian element. Many of the British <i>species</i> range across the
+Atlantic, and inhabit in an unchanged condition the northern parts of<span class="pagenum" id="Page_267">[267]</span>
+this district; and from the frequent occurrence of isolated specimens
+of other British species on the North American coast, we may presume
+that many more occasionally cross the Atlantic, but without being able
+to obtain a permanent footing.</p>
+
+<p>The genera peculiar to this district are few in number, and composed
+of very few species, viz. <i>Hemitripterus</i>, <i>Pammelas</i>,
+<i>Chasmodes</i>, <i>Cryptacanthodes</i>, and <i>Tautoga</i>.</p>
+
+<p>The close resemblance of what must be considered northern forms to
+those of Europe will be evident from the following list:—</p>
+
+<p><i>Mustelus, Rhina, Torpedo, Raja, Trygon.</i></p>
+
+<p><i>Labrax, Centropristis, Serranus; Pagrus, Chrysophrys; Sebastes,
+Hemitripterus; Cottus, Aspidophoroides; Uranoscopus; Micropogon,
+Pogonias, Sciæna; Trachurus, Pammelas; Cyclopterus, Liparis; Lophius;
+Anarrhichas, Chasmodes, Stichcæus, Centronotus, Cryptacanthodes,
+Zoarces.</i></p>
+
+<p><i>Tautoga, Ctenolabrus.</i></p>
+
+<p><i>Gadus, Merluccius, Phycis, Molva, Motella, Brosmius; Ophidium</i>
+(one species, perhaps identical with a Mediterranean species);
+<i>Ammodytes; Hippoglossus, Hippoglossoides, Rhombus, Pleuronectes</i>.</p>
+
+<p><i>Osmerus, Mallotus; Engraulis, Clupea; Conger.</i></p>
+
+<p><i>Syngnathus—Myxine—Branchiostoma.</i></p>
+
+<p>West Indian genera, or at least genera which are more developed within
+the tropics, and which extend more or less northwards in the North
+American district, are:—</p>
+
+<p><i>Pteroplatea</i> (also in the Mediterranean).</p>
+
+<p><i>Gerres, Dules (auriga), Lobotes, Ephippus; Sargus; Prionotus;
+Umbrina, Otolithus, Larimus; Sphyræna</i> (Mediterr.);
+<i>Trichiurus</i> (Mediterr.); <i>Elacate; Cybium, Trachynotus;
+Stromateus</i> (Mediterr.); <i>Caranx</i>; <i>Batrachus</i>
+(Mediterr.); <i>Malthe</i>.</p>
+
+<p><i>Pseudorhombus</i>, <i>Solea</i> (Mediterr.)</p>
+
+<p><i>Saurus</i> (Mediterr.); <i>Etrumeus, Albula, Elops, Megalops</i>.</p>
+
+<p><span class="pagenum" id="Page_268">[268]</span></p>
+
+<p><i>Hippocampus</i> (Mediterr.)</p>
+
+<p><i>Balistes, Monacanthus.</i></p>
+
+
+<h4>B. <span class="smcap">Shore Fishes of the Temperate North Pacific.</span></h4>
+
+<p>This fauna shows a great affinity to that of the temperate North
+Atlantic, not only in including a considerable proportion of identical
+genera, and even of species, but also in having its constituent parts
+similarly distributed. However, our knowledge of the ichthyology of
+this fauna is by no means complete. Very few collections have been
+made in Northern Japan, and on the coasts farther north of it; and,
+again, the ichthyology of the coasts of Southern California is but
+little known. Southern Japan has been well searched, but very little
+attention has been paid to the extent of the northward range of the
+species. In collections made by Mr. Swinhoe at Chefoo, in lat. 37° N.,
+the proportions of temperate and tropical fishes were found to be about
+equal. Thus, the details of the distribution of the fishes of these
+shores have still to be worked out; nevertheless, three divisions may
+be recognised which, for the present, may be defined as follows:—</p>
+
+<p>1. The fishes of the north-western shores, to about 37°
+lat. N., including the corresponding northern parts of
+Japan—<i>Kamtschatkan</i> district; this corresponds to the British
+district of the Atlantic.</p>
+
+<p>2. The fishes of Southern Japan and the corresponding shores of the
+continent of Asia, between 37° and 30° lat. N.—<i>Japanese</i>
+district, which corresponds to the Mediterranean.</p>
+
+<p>3. The fishes of the eastern shores southwards to the latitude of San
+Francisco—<i>Californian</i> district; this corresponds to the North
+American district of the Atlantic.</p>
+
+<p>Too little is known of the shore fishes of the coasts between San
+Francisco and the tropic to enable us to treat of it as a separate
+division.</p>
+
+<p><span class="pagenum" id="Page_269">[269]</span></p>
+
+<p>The Shore fishes of the North Pacific generally are composed of the
+following elements:—</p>
+
+<p><i>a.</i> Arctic forms which extend into the Arctic Ocean, and the
+majority of which are also found in the British district.</p>
+
+<p><i>b.</i> Peculiar forms limited to the North Pacific, like the
+<i>Heterolepidina</i>, <i>Embiotocidæ</i>, and certain Cottoid and
+Blennioid genera.</p>
+
+<p><i>c.</i> Forms identical with fishes of the Mediterranean.</p>
+
+<p><i>d.</i> Peculiar forms limited to the southern parts of Japan.</p>
+
+<p><i>e.</i> Tropical forms which have entered the North Pacific from the
+south.</p>
+
+<hr class="tb">
+
+<p>1. The small list of fishes which we can assign to the
+<i>Kamtschatkan</i> district is due rather to the imperfect manner
+in which its fauna has been explored than to its actual poverty of
+fishes; thus, although we may be sure that sooner or later the small
+kinds of Dog-fishes of the British district will be found there also,
+at present we have positive knowledge of the occurrence of only two
+Chondropterygians, viz. <i>Chimæra</i> and <i>Raja</i>. The species of
+the latter genus seem to be much less numerous than in the Atlantic.</p>
+
+<p>Of Acanthopterygians the following are known:—<i>Sebastes</i>;
+<i>Chirus</i>, <i>Agrammus</i>; <i>Podabrus</i>, <i>Blepsias</i>,
+<i>Cottus</i>, <i>Centridermichthys</i>, <i>Hemilepidotus</i>,
+<i>Agonus</i>; <i>Trichodon</i>; <i>Callionymus</i>; <i>Liparis</i>;
+<i>Dictyosoma</i>, <i>Stichæus</i>, <i>Centronotus</i>.</p>
+
+<p>Labroids are absent; they are clearly a type unable to endure great
+cold; of the Embiotocoids which represent them in the Pacific, one
+species only (a species of <i>Ditrema</i>) is known from this district.</p>
+
+<p>The Gadoids are, so far as we know at present, sparsely represented,
+viz. by isolated species of <i>Gadus</i>, <i>Motella</i>, and
+<i>Lotella</i>, the latter being an inhabitant of moderate depths
+rather than of the surface. <i>Hippoglossus</i>, <i>Pleuronectes</i>,
+and <i>Parophrys</i>, seem to occur everywhere at suitable localities.</p>
+
+<p><span class="pagenum" id="Page_270">[270]</span></p>
+
+<p>The Physostomes are nearly the same as in the British district, viz.
+a Smelt (<i>Hypomesus</i>), probably also the Arctic <i>Mallotus</i>,
+an Anchovy, several species of <i>Clupea</i>, and the Conger-eel. A
+very singular Salmonoid fish, <i>Salanx</i>, which is limited to the
+north-western Pacific, occurs in great abundance.</p>
+
+<p>Also, the Lophobranchs correspond in their development to those of the
+British district, <i>Nerophis</i> being replaced by <i>Urocampus</i>.</p>
+
+<p>Neither Myxinoids nor <i>Branchiostoma</i> have as yet been found.</p>
+
+<p class="p1">2. The <i>Japanese</i> district is, like the Mediterranean,
+distinguished by a great variety of forms; some of them are peculiar
+to it (marked <i>J.</i> in the following list); others occur in
+the Mediterranean, though also in other districts (<i>M.</i>) The
+resemblance to the Mediterranean is even greater than would appear from
+the following list of genera, inasmuch as a considerable number of
+species are identical in both districts. Three of the Berycoid genera
+have hitherto been found in the Japanese and Mediterranean districts
+only, and nowhere else. Another very singular fact is that some of
+the most characteristic genera, like <i>Mullus</i>, <i>Zeus</i>,
+<i>Callionymus</i>, <i>Centriscus</i>, inhabit the Mediterranean
+and Japanese districts, <i>but have never reached the opposite
+American coasts, either in the Atlantic or Pacific</i>; although,
+at least in the latter, the oceanic currents would rather favour
+than obstruct their dispersal in the direction towards America. Bold
+as the hypothesis may appear, we can only account for the singular
+distribution of these shore fishes by assuming that the Mediterranean
+and Japanese seas were in direct and open communication with each other
+within the period of the existence of the present Teleosteous Fauna.</p>
+
+<p>Gadoids have disappeared, or are represented by forms<span class="pagenum" id="Page_271">[271]</span> inhabiting
+moderate depths. Neither Myxine nor <i>Branchiostoma</i> are known to
+have as yet been found.</p>
+
+
+<p class="center"><i>List of Japanese Shore Fishes.</i></p>
+
+<p><i>Chimæra</i> (M.)</p>
+
+<p><i>Galeus</i> (M.), <i>Mustelus</i> (M.), <i>Triacis</i>,
+<i>Scyllium</i> (M.), <i>Crossorhinus</i>, <i>Pristiophorus</i>,
+<i>Cestracion</i>; <i>Rhina</i> (M.); <i>Rhinobatus</i>
+(M.), <i>Narcine</i>, <i>Raja</i> (M.), <i>Trygon</i> (M.),
+<i>Pteroplatea</i> (M.)</p>
+
+<p><i>Percalabrax</i> (J.), <i>Niphon</i> (J.), <i>Centropristis</i>,
+<i>Anthias</i> (M.), <i>Serranus</i> (M.), <i>Apogon</i>
+(M.), <i>Scombrops</i> (J.), <i>Acropoma</i>, <i>Anoplus</i>
+(J.), <i>Pristipoma</i> (M.), <i>Hapalogenys</i>
+(J.), <i>Histiopterus</i>, <i>Velifer</i> (J.),
+<i>Dentex</i> (M.), <i>Erythrichthys</i>—<i>Mullidæ</i>
+(M.)—<i>Girella</i>, <i>Pagrus</i> (M.), <i>Chrysophrys</i>
+(M.)—<i>Chilodactylus</i>—<i>Sebastes</i> (M.), <i>Scorpæna</i> (M.),
+<i>Aploactis</i>, <i>Trichopleura</i>, <i>Pelor</i>—<i>Monocentris</i>
+(J.), <i>Hoplostethus</i> (M.), <i>Beryx</i> (M.), <i>Polymixia</i>
+(M.)—<i>Platycephalus</i>, <i>Hoplichthys</i> (J.), <i>Bembras</i>
+(J.), <i>Prionotus</i>, <i>Lepidotrigla</i> (M.), <i>Trigla</i>
+(M.), <i>Peristethus</i> (M.)—<i>Uranoscopus</i> (M.),
+<i>Percis</i>, <i>Sillago</i>, <i>Latilus</i>.—<i>Sciæna</i>
+(M.), <i>Otolithus</i>—<i>Sphyræna</i> (M.)—<i>Lepidopus</i>
+(M.), <i>Trichiurus</i> (M.)—<i>Zeus</i> (M.)—<i>Caranx</i>,
+<i>Trachurus</i> (M.)—<i>Callionymus</i> (M.)—<i>Lophius</i>
+(M.), <i>Halieuthæa</i> (J.)—<i>Hoplognathus</i>—<i>Cepola</i>
+(M.)—<i>Centriscus</i> (M.), <i>Fistularia</i>.</p>
+
+<p><i>Heliastes</i> (M.)—<i>Labrichthys</i>, <i>Duymæria</i>,
+<i>Platyglossus</i>, <i>Novacula</i> (M.), <i>Julis</i> (M.),
+<i>Coris</i> (M.)</p>
+
+<p><i>Sirembo</i> (J.)—<i>Motella</i> (M.)—<i>Ateleopus</i> (J.)</p>
+
+<p><i>Pseudorhombus</i>, <i>Pleuronectes</i> (M.), <i>Solea</i> (M.),
+<i>Synaptura</i> (M.)</p>
+
+<p><i>Saurus</i> (M.), <i>Harpodon</i>.—<i>Salanx</i>
+(J.)—<i>Engraulis</i> (M.), <i>Clupea</i> (M.),
+<i>Etrumeus</i>—<i>Conger</i> (M.), <i>Congromuræna</i> (M.),
+<i>Murænesox</i> (M.), <i>Oxyconger</i>, <i>Myrus</i> (M.),
+<i>Ophichthys</i> (M.), <i>Muræna</i> (M.)</p>
+
+<p><i>Syngnathus</i> (M.), <i>Hippocampus</i> (M.), <i>Solenognathus</i>.</p>
+
+<p><i>Triacanthus</i>, <i>Monacanthus</i>, <i>Ostracion</i>.</p>
+
+<p><span class="pagenum" id="Page_272">[272]</span></p>
+
+<p>3. The <i>Californian</i> district includes a marked northern element,
+the principal constituents of which are identical with types occurring
+in the corresponding district of the Atlantic, viz. the North
+American, as exemplified by <i>Discoboli</i>, <i>Anarrhichas</i>,
+<i>Centronotus</i>, <i>Cottus</i>, <i>Hippoglossus</i>, <i>Clupea</i>
+(<i>harengus</i>), etc. But it possesses also, in the greatest
+degree of development, some types almost peculiar to itself, as the
+<i>Heterolepidina</i>, some remarkable Cottoid and Blennioid genera,
+and more especially the Embiotocoids—viviparous Pharyngognaths—which
+replace the Labroids of the other hemisphere. Gadoids are much less
+numerous than in the North American district. The southern forms are
+but little known, but it may be anticipated that, owing to the partial
+identity of the Faunæ of the two coasts of the Isthmus of Panama, a
+fair proportion of West Indian forms will be found to have entered this
+district from the south. The following are the principal genera:—</p>
+
+<p><i>Chimœra</i>, <i>Galeus</i>, <i>Mustelus</i>, <i>Triacis</i>,
+<i>Cestracion</i>, <i>Rhina</i>, <i>Raja</i>.</p>
+
+<p><i>Serranus</i>; <i>Chirus</i>, <i>Ophiodon</i>, <i>Zaniolepis</i>;
+<i>Sebastes</i>; <i>Nautichthys</i>, <i>Scorpœnichthys</i>,
+<i>Cottus</i>, <i>Centridermichthys</i>, <i>Hemilepidotus</i>,
+<i>Artedius</i>, <i>Prionotus</i>, <i>Agonus</i>; <i>Cyclopterus</i>,
+<i>Liparis</i>; <i>Anarrhichas</i>, <i>Neoclinus</i>,
+<i>Cebidichthys</i>, <i>Stichœus</i>, <i>Centronotus</i>,
+<i>Apodichthys</i>; <i>Psychrolutes</i>; <i>Auliscops</i>.</p>
+
+<p><i>Embiotocidœ</i>.</p>
+
+<p><i>Gadus</i>. <i>Hippoglossus</i>, <i>Psettichthys</i>,
+<i>Citharichthys</i>, <i>Paralichthys</i>, <i>Pleuronectes</i>,
+<i>Parophrys</i>.</p>
+
+<p><i>Osmerus</i>, <i>Thaleichthys</i>, <i>Hypomesus</i>;
+<i>Engraulis</i>, <i>Clupea</i>.</p>
+
+<p><i>Syngnathus</i>.</p>
+
+
+<h3>III.—<span class="smcap">The Equatorial Zone.</span></h3>
+
+<p>As we approach the Tropic from the north, the tribes characteristic
+of the Arctic and Temperate zones become scarcer, and disappear
+altogether: to be replaced by the greater variety of Tropical types.
+Of Chondropterygians, the <i>Chimœridœ</i>, <i>Spinacidœ</i>,
+<i>Mustelus</i>, and <i>Raja</i>, do not pass the<span class="pagenum" id="Page_273">[273]</span> Tropic, or appear
+in single species only; and of Teleosteans, the <i>Berycidæ</i>,
+<i>Pagrus</i>, the <i>Heterolepidina</i>, <i>Cottus</i> and allied
+genera, <i>Lophius</i>, <i>Anarrhichas</i>, <i>Stichæus</i>,
+<i>Lepadogaster</i>, <i>Psychrolutes</i>, <i>Centriscus</i>,
+<i>Notacanthus</i>, the <i>Labridæ</i> and <i>Embiotocidæ</i>, the
+<i>Lycodidæ</i>, <i>Gadidæ</i>, and marine <i>Salmonidæ</i> disappear
+either entirely, or retire from the shores and surface into the depths
+of the ocean.</p>
+
+<p>With regard to variety of forms, as well as to number of individuals,
+this zone far surpasses either of the temperate zones; in this
+respect, the life in the sea is as that on the land. Coast fishes
+are not confined to the actual coast-line, but abound on the coral
+reefs, with which some parts of the Atlantic and Pacific are studded,
+and many of which are submerged below the water. The abundance of
+animal and vegetable life which flourishes on them renders them the
+favourite pasture-grounds for the endless variety of coral-fishes
+(<i>Squamipinnes</i>, <i>Acronuridæ</i>, <i>Pomacentridæ</i>,
+<i>Julidæ</i>, <i>Plectognathi</i>, etc.), and for the larger predatory
+kinds. The colours and grotesque forms of the Fishes of the Tropics
+have justly excited the admiration of the earliest observers. Scarlet,
+black, blue, pink, red, yellow, etc., are arranged in patterns of the
+most bizarre fashion, mingling in spots, lines, bands; and reminding
+us of the words of Captain Cook when describing the coral-reefs of
+Palmerston Island: “The glowing appearance of the Mollusks was still
+inferior to that of the multitude of fishes that glided gently along,
+seemingly with the most perfect security. The colours of the different
+sorts were the most beautiful that can be imagined—the yellow, blue,
+red, black, etc., far exceeding anything that art can produce. Their
+various forms, also, contributed to increase the richness of this
+sub-marine grotto, which could not be surveyed without a pleasing
+transport.”</p>
+
+<p>Of Chondropterygians the <i>Scylliidæ</i>, <i>Pristis</i>
+(Saw-fishes), <i>Rhinobatidæ</i>, and <i>Trygonidæ</i> attain to the
+greatest development.<span class="pagenum" id="Page_274">[274]</span> Of Acanthopterygians <i>Centropristis</i>,
+<i>Serranus</i>, <i>Plectropoma</i>, <i>Mesoprion</i>,
+<i>Priacanthus</i>, <i>Apogon</i>, <i>Pristipoma</i>, <i>Hæmulon</i>,
+<i>Diagramma</i>, <i>Gerres</i>, <i>Scolopsis</i>, <i>Synagris</i>,
+<i>Cæsio</i>, <i>Mullidæ</i>, <i>Lethrinus</i>, <i>Squamipinnes</i>,
+<i>Cirrhites</i>, some genera of <i>Scorpænidæ</i>,
+<i>Platycephalus</i>, <i>Sciænidæ</i>, <i>Sphyræna</i>, <i>Caranx</i>
+<i>Equula</i>, <i>Callionymus</i>, <i>Teuthis</i>, <i>Acanthurus</i>,
+<i>Naseus</i>, are represented by numerous species; and the majority of
+these genera and families are limited to this zone. Of Pharyngognaths
+the <i>Pomacentridæ</i>, <i>Julidina</i>, and <i>Scarina</i>, are met
+with near every coral formation in a living condition. Of Gadoids,
+a singular minute form, <i>Bregmaceros</i>, is almost the only
+representative, the other forms belonging to deep water, and rarely
+ascending to the surface. Flat-fishes (<i>Pleuronectidæ</i>) are common
+on sandy coasts, and the majority of the genera are peculiar to the
+Tropics. Of <i>Physostomi</i> only the <i>Saurina</i>, <i>Clupeidæ</i>,
+and <i>Murænidæ</i> are represented, the <i>Clupeidæ</i> being
+exceedingly numerous in individuals, whilst the <i>Murænidæ</i>
+live more isolated, but show a still greater variety of species.
+Lophobranchii and Sclerodermi are generally distributed. Branchiostoma
+has been found on several coasts.</p>
+
+<p>Geographically it is convenient to describe the Coast fauna of the
+tropical Atlantic separately from that of the Indo-Pacific ocean. The
+differences between them, however, are far less numerous and important
+than between the freshwater or terrestrial faunæ of continental
+regions. The majority of the principal types are found in both, many of
+the species being even identical; but the species are far more abundant
+in the Indo-Pacific than in the Atlantic, owing to the greater extent
+of the archipelagoes in the former. But for the broken and varied
+character of the coasts of the West Indies, the shores of the tropical
+Atlantic would, by their general uniformity, afford but a limited
+variety of conditions to the development of specific and generic
+forms, whilst the deep inlets of the<span class="pagenum" id="Page_275">[275]</span> Indian ocean, with the varying
+configuration of their coasts, and the different nature of their
+bottom, its long peninsulas, and its archipelagoes, and the scattered
+islands of the tropical Pacific, render this part of the globe the
+most perfect for the development of fish-life. The fishes of the
+Indian and Pacific oceans (between the Tropics) are almost identical,
+and the number of species ranging from the Red Sea and east coast of
+Africa to Polynesia, even to its westernmost islands, is very great
+indeed. However, this Indo-Pacific fauna does not reach the Pacific
+coast of South America. The wide space devoid of islands, east of the
+Sandwich Islands and the Marquesas group, together with the current
+of cold water which sweeps northwards along the South American coast,
+has proved to be a very effectual barrier to the eastward extension
+of the Indo-Pacific fauna of coast fishes; and, consequently, we find
+an assemblage of fishes on the American coast and at the Galapagoes
+Islands, sufficiently distinct to constitute a distinct zoological
+division.</p>
+
+<p>The following list, which contains only the principal genera and groups
+of coast fishes, will give an idea of the affinity of the tropical
+Atlantic and Indo-Pacific:—<a id="FNanchor_28" href="#Footnote_28" class="fnanchor">[28]</a></p>
+
+<table class="smaller">
+  <tr>
+    <td class="cht"></td>
+    <td class="ctr sm">Trop.-Atl.</td>
+    <td class="ctr sm">Indo-Pac.</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Scylliidæ</td>
+    <td class="right3">—</td>
+    <td class="right3">13</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Pristis</i></td>
+    <td class="right3">3</td>
+    <td class="right3">4</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Rhinobatidæ</i></td>
+    <td class="right3">4</td>
+    <td class="right3">8</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Torpedinidæ</i></td>
+    <td class="right3">1</td>
+    <td class="right3">8</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Trygonidæ</i></td>
+    <td class="right3">14</td>
+    <td class="right3">24</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Etelis</i></td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Aprion</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Apsilus</i></td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Centropristis</i></td>
+    <td class="right3">15</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Anthias</i></td>
+    <td class="right3">4</td>
+    <td class="right3">5</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Serranus</i></td>
+    <td class="right3">30</td>
+    <td class="right3">85</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Plectropoma</i></td>
+    <td class="right3">11</td>
+    <td class="right3">5<span class="pagenum" id="Page_276">[276]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Grammistes</i></td>
+    <td class="right3">—</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Rhypticus</i></td>
+    <td class="right3">3</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Diploprion</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Myriodon</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Mesoprion</i></td>
+    <td class="right3">15</td>
+    <td class="right3">50</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Priacanthus</i></td>
+    <td class="right3">4</td>
+    <td class="right3">12</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Apogon</i> and <i>Chilodipterus</i></td>
+    <td class="right3">2</td>
+    <td class="right3">75</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Pristipoma</i></td>
+    <td class="right3">12</td>
+    <td class="right3">14</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Hæmulon</i></td>
+    <td class="right3">15</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Diagramma</i></td>
+    <td class="right3">—</td>
+    <td class="right3">30</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Gerres</i></td>
+    <td class="right3">12</td>
+    <td class="right3">16</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Scolopsis</i></td>
+    <td class="right3">—</td>
+    <td class="right3">20</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Dentex and <i>Symphorus</i></td>
+    <td class="right3">—</td>
+    <td class="right3">7</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Synagris</i> and <i>Pentapus</i></td>
+    <td class="right3">—</td>
+    <td class="right3">24</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Cæsio</i></td>
+    <td class="right3">—</td>
+    <td class="right3">12</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Mullidæ</td>
+    <td class="right3">5</td>
+    <td class="right3">22</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Sargus</td>
+    <td class="right3">7</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Lethrinus</i></td>
+    <td class="right3">1</td>
+    <td class="right3">18</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Chrysophrys</i></td>
+    <td class="right3">1</td>
+    <td class="right3">7</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Pimelepterus</i></td>
+    <td class="right3">1</td>
+    <td class="right3">5</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Squamipinnes</i></td>
+    <td class="right3">13</td>
+    <td class="right3">110</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Toxotes</i></td>
+    <td class="right3">—</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Cirrhites</i></td>
+    <td class="right3">—</td>
+    <td class="right3">20</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Scorpænidæ</td>
+    <td class="right3">2</td>
+    <td class="right3">65</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Myripristis</i></td>
+    <td class="right3">3</td>
+    <td class="right3">15</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Holocentrum</i></td>
+    <td class="right3">6</td>
+    <td class="right3">25</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Platycephalus</i></td>
+    <td class="right3">—</td>
+    <td class="right3">25</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Prionotus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Trigla</td>
+    <td class="right3">—</td>
+    <td class="right3">4</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Peristethus</td>
+    <td class="right3">2</td>
+    <td class="right3">6</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Uranoscopina</td>
+    <td class="right3">2</td>
+    <td class="right3">8</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Champsodon</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Percis</i></td>
+    <td class="right3">—</td>
+    <td class="right3">10</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Sillago</i></td>
+    <td class="right3">—</td>
+    <td class="right3">5</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Latilus</td>
+    <td class="right3">1</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Opisthognathus</i></td>
+    <td class="right3">2</td>
+    <td class="right3">5</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Pseudochromis</i></td>
+    <td class="right3">—</td>
+    <td class="right3">8</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Cichlops</i> and <i>Pseudoplesiops</i></td>
+    <td class="right3">—</td>
+    <td class="right3">2<span class="pagenum" id="Page_277">[277]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Sciænidæ</i></td>
+    <td class="right3">44</td>
+    <td class="right3">43</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Sphyræna</i></td>
+    <td class="right3">1</td>
+    <td class="right3">10</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Trichiuridæ</i></td>
+    <td class="right3">6</td>
+    <td class="right3">5</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Caranx</i></td>
+    <td class="right3">20</td>
+    <td class="right3">60</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Chorinemus</i></td>
+    <td class="right3">4</td>
+    <td class="right3">7</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Trachynotus</i></td>
+    <td class="right3">6</td>
+    <td class="right3">4</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Psettus</i></td>
+    <td class="right3">1</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Platax</i></td>
+    <td class="right3">—</td>
+    <td class="right3">7</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Zanclus</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Equula</i> and <i>Gazza</i></td>
+    <td class="right3">—</td>
+    <td class="right3">20</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Teuthis</i></td>
+    <td class="right3">—</td>
+    <td class="right3">30</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Acanthurus</i></td>
+    <td class="right3">3</td>
+    <td class="right3">42</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Naseus</i></td>
+    <td class="right3">—</td>
+    <td class="right3">12</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Kurtidæ</i></td>
+    <td class="right3">1</td>
+    <td class="right3">6</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Gobiodon</i></td>
+    <td class="right3">—</td>
+    <td class="right3">7</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Callionymus</td>
+    <td class="right3">—</td>
+    <td class="right3">17</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Batrachidæ</i></td>
+    <td class="right3">5</td>
+    <td class="right3">4</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Tetrabrachium</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Malthe</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Petroscirtes</i></td>
+    <td class="right3">—</td>
+    <td class="right3">30</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Clinus</td>
+    <td class="right3">6</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Dactyloscopus</i></td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Malacanthus</i></td>
+    <td class="right3">1</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Cepola</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Gobiesocidæ</td>
+    <td class="right3">5</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Amphisile</i></td>
+    <td class="right3">—</td>
+    <td class="right3">3</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Fistulariidæ</i></td>
+    <td class="right3">3</td>
+    <td class="right3">3</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Pomacentridæ</i></td>
+    <td class="right3">17</td>
+    <td class="right3">120</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Lachnolæmus</i></td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Julidina</i></td>
+    <td class="right3">36</td>
+    <td class="right3">190</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Pseudodax</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Scarina</i></td>
+    <td class="right3">21</td>
+    <td class="right3">65</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Pseudophycis</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Bregmaceros</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Ophidiidæ</td>
+    <td class="right3">3</td>
+    <td class="right3">7</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Fierasfer</i></td>
+    <td class="right3">—</td>
+    <td class="right3">6</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Pleuronectidæ</td>
+    <td class="right3">21</td>
+    <td class="right3">56</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Saurina</i></td>
+    <td class="right3">5</td>
+    <td class="right3">9<span class="pagenum" id="Page_278">[278]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht">Clupeidæ.</td>
+    <td class="right3">33</td>
+    <td class="right3">84</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Chirocentrus</i></td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Murænidæ</i></td>
+    <td class="right3">47</td>
+    <td class="right3">130</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Pegasus</i></td>
+    <td class="right3">—</td>
+    <td class="right3">3</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Solenostoma</i></td>
+    <td class="right3">—</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Syngnathidæ</td>
+    <td class="right3">7</td>
+    <td class="right3">41</td>
+  </tr>
+
+  <tr>
+    <td class="cht"><i>Sclerodermi</i></td>
+    <td class="right3">16</td>
+    <td class="right3">67</td>
+  </tr>
+
+  <tr>
+    <td class="cht">Gymnodontes</td>
+    <td class="right3">23</td>
+    <td class="right3">40</td>
+  </tr>
+</table>
+
+
+<h4>A. <i>Shore Fishes of the Tropical Atlantic.</i></h4>
+
+<p>The boundaries of the tropical Atlantic extend zoologically a few
+degrees beyond the Northern and Southern Tropics, but as the mixture
+with the types of the temperate zone is very gradual, no distinct
+boundary line can be drawn between the tropical and temperate faunæ.</p>
+
+<p>Types, almost exclusively limited to it, and not found in the
+Indo-Pacific, are few in number, as <i>Centropristis</i>,
+<i>Rhypticus</i>, <i>Hæmulon</i>, <i>Malthe</i>. A few
+others preponderate with regard to the number of species,
+as <i>Plectropoma</i>, <i>Sargus</i>, <i>Trachynotus</i>,
+<i>Batrachidæ</i>, and <i>Gobiesocidæ</i>. The Sciænoids are equally
+represented in both oceans. All the remainder are found in both; but in
+the minority in the Atlantic, where they are sometimes represented by
+one or two species only (for instance, <i>Lethrinus</i>).</p>
+
+
+<h4>B. <i>Shore Fishes of the Tropical Indo-Pacific Ocean.</i></h4>
+
+<p>The ichthyological boundaries of this part of the tropical zone may be
+approximately given as 30° of lat. N. and S.; on the Australian coasts
+it should probably be placed still farther south, viz., to 34°; it
+includes, as mentioned above, the Sandwich Islands, and all the islands
+of the South Sea, but not the American coasts.</p>
+
+<p>Some eighty genera of Shore fishes are peculiar to the Indo-Pacific,
+but the majority consists of one or a few species<span class="pagenum" id="Page_279">[279]</span> only; comparatively
+few have a plurality of species, as <i>Diagramma</i>, <i>Lethrinus</i>,
+<i>Equula</i>, <i>Teuthis</i>, <i>Amphiprion</i>, <i>Dascyllus</i>,
+<i>Choerops</i>, <i>Chilinus</i>, <i>Anampses</i>, <i>Stethojulis</i>,
+<i>Coris</i>, <i>Coilia</i>.</p>
+
+<p>The Sea-perches, large and small, which feed on Crustaceans and
+other small fishes, and the coral-feeding Pharyngognaths are the
+types which show the greatest generic and specific variety in the
+Indo-Pacific. Then follow the <i>Squamipinnes</i> and <i>Murænidæ</i>,
+the <i>Clupeidæ</i> and <i>Carangidæ</i> families in which the
+variety is more that of species than of genus. The <i>Scorpænidæ</i>,
+<i>Pleuronectidæ</i>, <i>Acronuridæ</i>, <i>Sciænidæ</i>,
+<i>Syngnathidæ</i>, and <i>Teuthyes</i>, are those which contribute
+the next largest contingents. Of shore-loving Chondropterygians the
+<i>Scylliidæ</i> and <i>Trygonidæ</i> only are represented in moderate
+numbers, though they are more numerous in this ocean than in any other.</p>
+
+
+<h4>C. <i>Shore Fishes of the Pacific Coasts of Tropical America</i>.</h4>
+
+<p>As boundaries within which this fauna is comprised, may be indicated
+30° lat. N. and S., as in the Indo-Pacific. Its distinction from the
+Indo-Pacific lies in the almost entire absence of coral-feeding fishes.
+There are scarcely any Squamipinnes, Pharyngognaths or Acronuridæ, and
+the Teuthyes are entirely absent. The genera that remain are such as
+are found in the tropical zone generally, but the species are entirely
+different from those of the Indo-Pacific. They are mixed with a
+sprinkling of peculiar genera, consisting of one or two species, like
+<i>Discopyge</i>, <i>Hoplopagrus</i>, <i>Doydixodon</i>, but they are
+too few in number to give a strikingly peculiar character to this fauna.</p>
+
+<p>The Three districts are distinguishable:—</p>
+
+<p>a. <i>Central American district</i>, in which we include, for the
+present, Lower California, shows so near an affinity to the tropical
+Atlantic that, if it were not separated from it by the<span class="pagenum" id="Page_280">[280]</span> neck of land
+uniting the two American Continents, it would most assuredly be
+regarded as a portion of the Fauna of the tropical Atlantic. With
+scarcely any exceptions the genera are identical, and of the species
+found on the Pacific side nearly one-half have proved to be the same
+as those of the Atlantic. The explanation of this fact has been found
+in the existence of communications between the two oceans by channels
+and straits which must have been open till within a recent period.
+The isthmus of Central America was then partially submerged, and
+appeared as a chain of islands similar to that of the Antilles; but as
+the reef-building corals flourished chiefly north and east of those
+islands, and were absent south and west of them, reef-fishes were
+excluded from the Pacific shores when the communications were destroyed
+by the upheaval of the land.</p>
+
+<p><i>b</i>. The <i>Galapagoes district</i> received its coast fauna
+principally from the Central American district, a part of the
+species being absolutely the same as on the coast of the Isthmus
+of Panama, or as in the West Indies. Yet the isolation of this
+group has continued a sufficiently long period to allow of the
+development of a number of distinct species of either peculiarly
+Atlantic genera (such as <i>Centropristis</i>, <i>Rhypticus</i>,
+<i>Gobiesox</i>, <i>Prionotus</i>), or at least tropical genera
+(such as <i>Chrysophrys</i>, <i>Pristipoma</i>, <i>Holacanthus</i>,
+<i>Caranx</i>, <i>Balistes</i>). A few other types from the Peruvian
+coast (<i>Doydixodon</i>), or even from Japan (<i>Prionurus</i>),
+have established themselves in this group of islands. A species of
+<i>Cestracion</i> has also reached the Galapagoes, but whether from the
+south, north, or west, cannot be determined.</p>
+
+<p>The presence of the Atlantic fauna on the Pacific side is felt still
+farther west than the Galapagoes, some Atlantic species having reached
+the Sandwich Islands, as <i>Chætodon humeralis</i> and <i>Blennius
+brevipinnis</i>.</p>
+
+<p>c. The <i>Peruvian district</i> possesses a very limited variety<span class="pagenum" id="Page_281">[281]</span> of
+shore fishes, which belong, with few exceptions, like <i>Discopyge</i>,
+<i>Hoplognathus</i>, <i>Doydixodon</i>, to genera distributed
+throughout the tropical zone, or even beyond it. But the species,
+so far as they are known at present, are distinct from those of the
+Indo-Pacific, as well as of the tropical Atlantic; and therefore
+this district cannot be joined either to the Central American or the
+Galapagoes.</p>
+
+
+<h3>IV.—<span class="smcap">The Southern Temperate Zone</span>.</h3>
+
+<p>This zone includes the coasts of the southern extremity of Africa, from
+about 30° lat. S., of the south of Australia with Tasmania, of New
+Zealand, and the Pacific and Atlantic coasts of South America between
+30° and 50° lat. S.</p>
+
+<p>The most striking character of this fauna is the reappearance of types
+inhabiting the corresponding latitudes of the Northern Hemisphere,
+and not found in the intervening tropical zone. This interruption of
+the continuity in the geographical distribution of Shore-fishes is
+exemplified by species as well as genera, for instance—<i>Chimæra
+monstrosa</i>, <i>Galeus canis</i>, <i>Acanthias vulgaris</i>,
+<i>Acanthias blainvillii</i>, <i>Rhina squatina</i>, <i>Zeus faber</i>,
+<i>Lophius piscatorius</i>, <i>Centriscus scolopax</i>, <i>Engraulis
+encrasicholus</i>, <i>Clupea sprattus</i>, <i>Conger vulgaris</i>.
+Instances of genera are still more numerous—<i>Cestracion</i>,
+<i>Spinax</i>, <i>Pristiophorus</i>, <i>Raja</i>; <i>Callanthias</i>,
+<i>Polyprion</i>, <i>Histiopterus</i>, <i>Cantharus</i>, <i>Box</i>,
+<i>Girella</i>, <i>Pagellus</i>, <i>Chilodactylus</i>, <i>Sebastes</i>,
+<i>Aploactis</i>, <i>Agonus</i>, <i>Lepidopus</i>, <i>Cyttus</i>,
+<i>Psychrolutidæ</i>, <i>Notacanthus</i>; <i>Lycodes</i>,
+<i>Merluccius</i>, <i>Lotella</i>, <i>Phycis</i>, <i>Motella</i>;
+<i>Aulopus</i>; <i>Urocampus</i>, <i>Solenognathus</i>; <i>Myxine</i>.</p>
+
+<p>Naturally, where the coasts of the tropical zone are continuous
+with those of the temperate, a number of tropical genera enter the
+latter, and genera which we have found between the tropics as well
+as in the temperate zone of the Northern Hemisphere, extend in a
+similar manner towards the<span class="pagenum" id="Page_282">[282]</span> south. But the truly tropical forms are
+absent; there are no <i>Squamipinnes</i>, scarcely any <i>Mullidæ</i>,
+no <i>Acronuri</i>, no <i>Teuthyes</i>, no <i>Pomacentridæ</i>
+(with a single exception on the coast of Chili), only one genus of
+<i>Julidina</i>, no <i>Scarina</i>, which are replaced by another
+group of Pharyngognaths, the <i>Odacina</i>. The <i>Labrina</i>, so
+characteristic of the temperate zone of the Northern Hemisphere,
+reappear in a distinct genus (<i>Malacopterus</i>) on the coast of Juan
+Fernandez.</p>
+
+<p>The family of <i>Berycidæ</i>, equally interesting with regard to their
+distribution in time and in space, consists of temperate and tropical
+genera. The genus by which this family is represented in the southern
+temperate zone (<i>Trachichthys</i>) is much more nearly allied to the
+northern than to the tropical genera.</p>
+
+<p>The true <i>Cottina</i> and <i>Heterolepidina</i> (forms with a bony
+stay of the præoperculum, which is generally armed) have not crossed
+the tropical zone; they are replaced by fishes extremely similar in
+general form, and having the same habits, but lacking that osteological
+peculiarity. Their southern analogues belong chiefly to the family
+<i>Trachinidæ</i>, and are types of genera peculiar to the Southern
+Hemisphere.</p>
+
+<p>The <i>Discoboli</i> of the Northern Hemisphere have likewise
+not penetrated to the south, where they are represented by
+<i>Gobiesocidæ</i>. These two families replace each other in their
+distribution over the globe.</p>
+
+<p>Nearly all the <i>Pleuronectidæ</i> (but they are not numerous) belong
+to distinct genera, some, however, being remarkably similar in general
+form to the northern <i>Pleuronectes</i>.</p>
+
+<p>With Gadoids <i>Myxinidæ</i> reappear, one species being extremely
+similar to the European Myxine. <i>Bdellostoma</i> is a genus peculiar
+to the southern temperate zone.</p>
+
+<p>As in the northern temperate zone, so in the southern, the number of
+individuals and the variety of forms is much less than between the
+tropics. This is especially apparent<span class="pagenum" id="Page_283">[283]</span> on comparing the numbers of
+species constituting a genus. In this zone genera composed of more than
+ten species are the exception, the majority having only from one to
+five.</p>
+
+<p>The proportion of genera limited to this zone is rather high; they
+will be indicated under the several districts, which we distinguish on
+geographical rather than zoological grounds.</p>
+
+<p class="p1">1. The <i>Cape of Good Hope</i> district.</p>
+
+<p>The principal genera found in this district are the following (those
+limited to the entire zone being marked with a single (*) and those
+peculiar to this district with a double (**) asterisk):—</p>
+
+<p><i>Chimæra</i>, *<i>Callorhynchus</i>, <i>Galeus</i>,
+**<i>Leptocarcharias</i>, <i>Scyllium</i>, <i>Acanthias</i>,
+<i>Rhinobatus</i>, <i>Torpedo</i>, <i>Narcine</i>, <i>Astrape</i>,
+<i>Raja</i>.</p>
+
+<p><i>Serranus</i>, <i>Dentex</i>, <i>Pristipoma</i>; <i>Cantharus</i>,
+<i>Box</i>, **<i>Dipterodon</i>, <i>Sagrus</i>, <i>Pagrus</i>,
+<i>Pagellus</i>, <i>Chrysophrys</i>; *<i>Chilodactylus</i>;
+<i>Sebastes</i>, *<i>Agriopus</i>; <i>Trigla</i>; <i>Sphyræna</i>;
+<i>Lepidopus</i>, <i>Thyrsites</i>; <i>Zeus</i>; <i>Caranx</i>;
+<i>Lophius</i>; <i>Clinus</i> (10 species), <i>Cristiceps</i>;
+**<i>Chorisochismus</i>.</p>
+
+<p>*<i>Halidesmus</i>, *<i>Genypterus</i>, <i>Motella</i>.</p>
+
+<p><i>Syngnathus</i>.—*<i>Bdellostoma</i>.</p>
+
+<p>This list contains many northern forms, which in conjunction with the
+peculiarly southern types (<i>Callorhynchus</i>, <i>Chilodactylus</i>,
+<i>Agriopus</i>, <i>Clinus</i>, <i>Genypterus</i>, <i>Bdellostoma</i>)
+leave no doubt that this district belongs to the southern temperate
+zone, whilst the Freshwater fishes of South Africa are members of
+the tropical fauna. Only a few (<i>Rhinobatus</i>, <i>Narcine</i>,
+<i>Astrape</i>, and <i>Sphyræna</i>) have entered from the neighbouring
+tropical coasts. The development of Sparoids is greater than in any of
+the other districts of this zone, and may be regarded as one of its
+distinguishing features.</p>
+
+<p>2. The <i>South Australian</i> district comprises the southern coasts
+of Australia (northwards, about to the latitude of<span class="pagenum" id="Page_284">[284]</span> Sydney), Tasmania,
+and New Zealand. It is the richest in the southern temperate zone,
+partly in consequence of a considerable influx of tropical forms on the
+eastern coast of Australia, where they penetrate farther southwards
+than should have been expected from merely geographical considerations;
+partly in consequence of the thorough manner in which the ichthyology
+of New South Wales and New Zealand has been explored. On the other
+hand, the western half of the south coast of Australia is still almost
+a <i>terra incognita</i>.</p>
+
+<p>The shore-fishes of New Zealand are not so distinct from those of
+south-eastern Australia as to deserve to be placed in a separate
+district. Beside the genera which enter this zone from the Tropics,
+and which are more numerous on the Australian coast than on that of
+New Zealand, and beside a few very local genera, the remainder are
+identical. Many of the South Australian species, besides, are found
+also on the coasts of New Zealand. The principal points of difference
+are the extraordinary development of Monacanthus on the coast of South
+Australia, and the apparently total absence in Australia of Gadoids,
+which in the New Zealand Fauna are represented by six genera.</p>
+
+
+<p class="center"><i>Shore-fishes of the South Australian district.</i></p>
+
+<table class="smaller">
+  <tr>
+    <td class="cht"></td>
+    <td class="ctr">South Australia<br>
+                    and Tasmania.</td>
+    <td class="ctr">New Zealand.</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Callorhynchus (antarcticus).</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Galeus (canis)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Scyllium</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Parascyllium</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Crossorhinus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Cestracion</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Mustelus (antarcticus)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Acanthias (vulgaris and blainvillii)</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Rhina</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Pristiophorus</td>
+    <td class="right3">1</td>
+    <td class="right3">—<span class="pagenum" id="Page_285">[285]</span></td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Trygonorhina (fasciata)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Rhinobatus</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Torpedo</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Narcine</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Raja</td>
+    <td class="right3">3</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Trygon (Urolophus)</td>
+    <td class="right3">3</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Enoplosus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Anthias (richardsonii)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Callanthias</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Serranus</td>
+    <td class="right3">x<a id="FNanchor_29" href="#Footnote_29" class="fnanchor">[29]</a></td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Plectropoma</td>
+    <td class="right3">4</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Lanioperca</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Arripis</td>
+    <td class="right3">3</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Histiopterus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Erythrichthys</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Haplodactylus</td>
+    <td class="right3">2</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Girella</td>
+    <td class="right3">4</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Tephræops</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Pagrus</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Scorpis</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Atypichthys</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Trachichthys</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Chironemus</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Holoxenus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Chilodactylus</td>
+    <td class="right3">9</td>
+    <td class="right3">4</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Nemadactylus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Latris</td>
+    <td class="right3">2</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Scorpæna</td>
+    <td class="right3">4</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Glyptauchen</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Centropogon</td>
+    <td class="right3">2</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Agriopus</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Aploactis</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Pentaroge</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Platycephalus</td>
+    <td class="right3">5</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Lepidotrigla</td>
+    <td class="right3">3</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Trigla</td>
+    <td class="right3">3</td>
+    <td class="right3">1<span class="pagenum" id="Page_286">[286]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Anema</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Crapatalus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Kathetostoma</td>
+    <td class="right3">1</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Leptoscopus</td>
+    <td class="right3">1</td>
+    <td class="right3">3</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Percis</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Aphritis</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Sillago</td>
+    <td class="right3">2</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Bovichthys</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Notothenia</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Sphyræna</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Lepidopus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Trichiurus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Thyrsites</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Platystethus</td>
+    <td class="right3">—</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Zeus (faber)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Cyttus</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Trachurus (trachurus)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Caranx</td>
+    <td class="right3">x</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Seriolella</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Pempheris</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Callionymus</td>
+    <td class="right3">3</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Batrachus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Brachionichthys</td>
+    <td class="right3">2</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Saccarius</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Clinus</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Lepidoblennius</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Cristiceps and Tripterygium</td>
+    <td class="right3">4</td>
+    <td class="right3">5</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Patæcus</td>
+    <td class="right3">3</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Acanthoclinus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Diplocrepis</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Crepidogaster</td>
+    <td class="right3">3</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Trachelochismus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Neophrynichthys</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Centriscus</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Notacanthus (sexspinis)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Labrichthys</td>
+    <td class="right3">8</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Odax</td>
+    <td class="right3">5</td>
+    <td class="right3">1<span class="pagenum" id="Page_287">[287]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Coridodax</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Olistherops</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Siphonognathus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Gadus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Merluccius</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Lotella</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Pseudophycis</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Motella</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Bregmaceros</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Genypterus</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Lophonectes</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Brachypleura</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Pseudorhombus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Ammotretis</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Rhombosolea</td>
+    <td class="right3">3</td>
+    <td class="right3">3</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Peltorhamphus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Solea</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Aulopus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Gonorhynchus (greyi)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Engraulis (encrasicholus)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Clupea</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Chilobranchus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Conger (vulgaris)</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Ophichthys</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Murænichthys</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Congromuræna</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Syngnathus</td>
+    <td class="right3">5</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Ichthyocampus</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Nannocampus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Urocampus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Stigmatophora</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Solenognathus</td>
+    <td class="right3">2</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Phyllopteryx</td>
+    <td class="right3">2</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Monacanthus</td>
+    <td class="right3">15</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Ostracion</td>
+    <td class="right3">3</td>
+    <td class="right3"></td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Bdellostoma</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Branchiostoma</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+</table>
+
+<p><span class="pagenum" id="Page_288">[288]</span></p>
+
+<p>3. The coast-line of the <i>Chilian district</i> extends over 20
+degrees of latitude only, and is nearly straight. In its northern and
+warmer parts it is of a very uniform character, and exposed to high and
+irregular tides, and to remarkable and sudden changes of the levels of
+land and water, which must seriously interfere with fishes living and
+propagating near the shore. No river of considerable size interrupts
+the monotony of the physical conditions, to offer an additional element
+in favour of the development of littoral animals. In the southern
+parts, where the coast is lined with archipelagoes, the climate is too
+severe for the majority of fishes. All these conditions combine to
+render this district comparatively poor as regards variety of Shore
+fishes, as will be seen from the following list:—</p>
+
+<p>*Callorhynchus; Scyllium, Acanthias, Spinax; Urolophus.</p>
+
+<p>Serranus, Plectropoma, Polyprion, Pristipoma, Erythrichthys;
+*Haplodactylus; *Scorpis; Chilodactylus, **Mendosoma; Sebastes,
+*Agriopus; Trigla, Agonus; *Aphritis, *Eleginus, Pinguipes, Latilus,
+Notothenia (1 sp.) Umbrina; Thyrsites; Trachurus, Caranx, *Seriolella;
+Porichthys; **Myxodes, Clinus; Sicyases, Gobiesox.</p>
+
+<p>Heliastes; **Malacopterus; *Labrichthys.</p>
+
+<p>Merluccius; *Genypterus; Pseudorhombus.</p>
+
+<p>Engraulis, Clupea; Ophichthys, Muræna.</p>
+
+<p>Syngnathus.—*Bdellostoma.</p>
+
+<p>Of these genera six only are not found in other districts of this
+zone. Three are peculiar to the Chilian district; <i>Porichthys</i>
+and <i>Agonus</i> have penetrated so far southwards from the Peruvian
+and Californian districts; and <i>Polyprion</i> is one of those
+extraordinary instances in which a very specialised form occurs at
+almost opposite points of the globe, without having left a trace of
+its previous existence in, or of its passage through, the intermediate
+space.</p>
+
+<p><span class="pagenum" id="Page_289">[289]</span></p>
+
+<p>4. The <i>Patagonian district</i> is, with the exception of the
+neighbourhood of the mouth of the Rio de la Plata, almost unknown.
+In that estuary occur <i>Mustelus vulgaris</i>, two <i>Raja</i>,
+two <i>Trygon</i>, several Sciænoids, <i>Paropsis signata</i> and
+<i>Percophis brasilianus</i> (two fishes peculiar to this coast),
+<i>Prionotus punctatus</i>, <i>Læmonema longifilis</i> (a Gadoid),
+a <i>Pseudorhombus</i>, two Soles, <i>Engraulis olidus</i>, a
+<i>Syngnathus</i>, <i>Conger vulgaris</i>, and <i>Ophichthys
+ocellatus</i>; and if we notice the occurrence of a <i>Serranus</i> and
+<i>Caranx</i>, of <i>Aphritis</i> and <i>Pinguipes</i>, and of two or
+three <i>Clupea</i>, we shall have enumerated all that is known of this
+fauna. The fishes of the southern part, viz. the coast of Patagonia
+proper, southwards to Magelhæn’s Straits, are unknown; which is the
+more to be regretted, as it is most probably the part in which the
+characteristic types of this district are most developed.</p>
+
+
+<h3>V.—<span class="smcap">Shore Fishes of the Antarctic Ocean.</span></h3>
+
+<p>To this fauna we refer the shore fishes of the southernmost extremity
+of South America, from 50° lat. S., with Tierra del Fuego and the
+Falkland Islands, and those of Kerguelen’s Land, with Prince Edward’s
+Island. No fishes are known from the other oceanic islands of these
+latitudes.</p>
+
+<p>In the Southern Hemisphere surface fishes do not extend so far towards
+the Pole as in the Northern; none are known from beyond 60° lat. S.,
+and the Antarctic Fauna, which is analogous to the Arctic Fauna,
+inhabits coasts more than ten degrees nearer to the equator. It is
+very probable that the shores between 60° and the Antarctic circle
+are inhabited by fishes sufficiently numerous to supply part of the
+means of subsistence for the large Seals which pass there at least
+some season of the year, but hitherto none have been obtained by
+naturalists; all that the present state of our knowledge justifies us
+in saying is, that the general character of<span class="pagenum" id="Page_290">[290]</span> the Fauna of Magelhæn’s
+Straits and Kerguelen’s Land is extremely similar to that of Iceland
+and Greenland.</p>
+
+<p>As in the arctic Fauna, Chondropterygians are scarce, and
+represented by <i>Acanthias vulgaris</i> and species of <i>Raja</i>.
+<i>Holocephali</i> have not yet been found so far south, but
+<i>Callorhynchus</i>, which is not uncommon near the northern boundary
+of this fauna, will prove to extend into it.</p>
+
+<p>As to Acanthopterygians, <i>Cataphracti</i> and <i>Scorpænidæ</i> are
+represented as in the arctic Fauna, two of the genera (<i>Sebastes</i>
+and <i>Agonus</i>) being identical. The <i>Cottidæ</i> are replaced by
+six genera of <i>Trachinidæ</i>, remarkably similar in form to arctic
+types; but <i>Discoboli</i> and the characteristic Arctic Blennioids
+are absent.</p>
+
+<p>Gadoid Fishes reappear, but are less developed; as usual they are
+accompanied by <i>Myxine</i>. The reappearance of so specialised a
+genus as <i>Lycodes</i> is most remarkable. Flat-fishes are scarce as
+in the North, and belong to peculiar genera.</p>
+
+<p>Physostomes are probably not entirely absent, but hitherto none have
+been met with so far south. Lophobranchs are scarce, as in the Arctic
+zone; however, it is noteworthy that a peculiar genus, with persistent
+embryonic characters (<i>Protocampus</i>), is rather common on the
+shores of the Falkland Islands.</p>
+
+<p>The following are the genera known from this zone. Those with a
+single asterisk (*) are known to extend into the Temperate zone, but
+not beyond it; those with a double asterisk (**) are limited to the
+Antarctic shores:—</p>
+
+<table class="smaller">
+  <tr>
+    <td class="cht"></td>
+    <td class="ctr">Magelhæn’s and<br>
+                    Falkland.</td>
+    <td class="ctr">Kerguelen.</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Acanthias vulgaris</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Raja</td>
+    <td class="right3">1</td>
+    <td class="right3">2</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Psammobatis</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Sebastes</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Zanclorhynchus</td>
+    <td class="right3">—</td>
+    <td class="right3">1<span class="pagenum" id="Page_291">[291]</span></td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Agriopus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Agonus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Aphritis</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Eleginus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Chænichthys</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Bovichthys</td>
+    <td class="right3">2</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chti">*Notothenia</td>
+    <td class="right3">8</td>
+    <td class="right3">7</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Harpagifer</td>
+    <td class="right3">1</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Lycodes</td>
+    <td class="right3">4</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Magnea</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Lotella</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Merluccius</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Lepidopsetta</td>
+    <td class="right3">—</td>
+    <td class="right3">1</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Thysanopsetta</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Syngnathus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht">**Protocampus</td>
+    <td class="right3">1</td>
+    <td class="right3">—</td>
+  </tr>
+
+  <tr>
+    <td class="chtii">Myxine</td>
+    <td class="right3b">1</td>
+    <td class="right3b">—</td>
+  </tr>
+
+  <tr>
+    <td class="cht"></td>
+    <td class="right3bd">31</td>
+    <td class="right3bd">13</td>
+  </tr>
+
+</table>
+
+  <div class="figcenter" id="fig108" style="max-width: 525px">
+     <img
+    class="p1"   
+    src="images/fig108.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 108.—<i>Chænichthys rhinoceratus</i>, shores of
+the Antarctic Ocean.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_292">[292]</span></p>
+
+<h2 class="smaller">CHAPTER XX.<br>
+<span class="subhed">DISTRIBUTION OF PELAGIC FISHES.</span></h2></div>
+
+<p>Pelagic Fishes,—that is, fishes inhabiting the surface of mid-ocean
+(see p. 255), belong to various orders, viz. Chondropterygians,
+Acanthopterygians, Physostomes, Lophobranchs, and Plectognaths. But
+neither Anacanths nor Pharyngognaths contribute to this series of the
+Marine Fauna. The following genera and families are included in it:—</p>
+
+<p><span class="smcap">Chondropterygii</span>: Carcharias, Galeocerdo, Thalassorhinus,
+Zygæna, Triænodon, Lamnidæ, Rhinodon, Notidanidæ, Læmargus,
+Euprotomicrus, Echinorhinus, Isistius; Myliobatidæ.</p>
+
+<p><span class="smcap">Acanthopterygii</span>: Dactylopterus, Micropteryx, Scombrina,
+Gastrochisma, Nomeus, Centrolophus, Coryphænina, Seriola, Temnodon,
+Naucrates, Psenes, Xiphiidæ, Antennarius.</p>
+
+<p><span class="smcap">Physostomi</span>: Sternoptychidæ, Scopelus, Astronesthes,
+Scombresocidæ (majority).</p>
+
+<p><span class="smcap">Lophobranchii</span>: Hippocampus.</p>
+
+<p><span class="smcap">Plectognathi</span>: Orthagoriscus, and some other Gymnodonts.</p>
+
+<p>Pelagic fishes differ much from one another in their mode of life. The
+majority are excellent swimmers, which not only can move with great
+rapidity, but also are possessed of great powers of endurance, and are
+thus enabled to continue their course for weeks, apparently without
+the necessity of rest: such are many Sharks, Scombroids, Dolphins,
+Pilot-fish, Sword-fishes. In some, as in <i>Dactylopterus</i> and
+<i>Exocoetus</i>, the ability of taking flying leaps out of the water
+is superadded to the power of swimming (Flying-fishes). But in others
+the power<span class="pagenum" id="Page_293">[293]</span> of swimming is greatly reduced, as in <i>Antennarius</i>,
+<i>Hippocampus</i>, and Gymnodonts; they frequent places in the
+ocean covered with floating seaweed, or drift on the surface without
+resistance, at the mercy of wind and current. The <i>Echeneis</i>
+or Sucking-fishes attach themselves to other large fish, ships, or
+floating objects, and allow themselves to be carried about, unless
+change of climate or want of food obliges them to abandon their
+temporary carrier. Finally, another class of Pelagic fishes come to
+the surface of the ocean during the night only; in the day time they
+descend to some depth, where they are undisturbed by the rays of the
+sun or the agitation of the surface-water: such are <i>Brama</i>, the
+<i>Sternoptychidæ</i>, <i>Scopelus</i>, <i>Astronesthes</i>; fishes,
+the majority of which are provided with those extraordinary luminary
+organs that we find so much developed in the true Deep-sea fishes.
+Indeed, this last kind of Pelagic fishes forms a passage to the
+Deep-sea forms.</p>
+
+<p>Pelagic fishes, like shore fishes, are most numerous in the Tropical
+Zone; and, with few exceptions (<i>Echinorhinus</i>, <i>Psenes</i>,
+<i>Sternoptychidæ</i>, <i>Astronesthes</i>), the same genera are
+represented in the tropical Atlantic as well as in the Indo-Pacific.
+The number of identical species occurring in both these oceans is
+great, and probably still greater than would appear from systematic
+lists, in which there are retained many specific names that were given
+at a time when species were believed to have a very limited range.
+The Pelagic fauna of the tropics gradually passes into that of the
+temperate zones, only a few genera, like <i>Cybium</i>, <i>Psenes</i>,
+<i>Antennarius</i>, being almost entirely confined to the tropics. All
+the other tropical genera range into the temperate zones, but their
+representatives become scarcer with the increasing distance from the
+equator. North of 40° lat. N. many genera have disappeared, or are met
+with in isolated examples only, as <i>Carcharias</i>, <i>Zygæna</i>,
+<i>Notidanus</i>, <i>Myliobatidæ</i>, <i>Dactylopterus</i>,
+<i>Echeneis</i>,<span class="pagenum" id="Page_294">[294]</span> <i>Nomeus</i>, <i>Coryphæna</i>, <i>Schedophilus</i>,
+<i>Seriola</i>, <i>Temnodon</i>, <i>Antennarius</i>,
+<i>Sternoptychidæ</i>, <i>Astronesthes</i>, <i>Exocoetus</i>,
+<i>Tetrodon</i>, <i>Diodon</i>; and only one genus of Sharks,
+<i>Galeocerdo</i>, approaches the Arctic circle. Some few species, like
+<i>Antennarius</i>, <i>Scopelus</i>, are carried by currents near to
+the northern confines of the temperate zones; but such occurrences are
+accidental, and these fishes must be regarded as entirely foreign to
+the fauna of those latitudes. On the other hand, some Pelagic fishes
+inhabit the temperate zones, whilst their occurrence within the tropics
+is very problematical; thus, in the Atlantic, <i>Thalassorhinus</i>,
+<i>Selache</i>, <i>Læmargus</i>, <i>Centrolophus</i>, <i>Diana</i>,
+<i>Ausonia</i>, <i>Lampris</i> (all genera composed of one or two
+species only). Beside the Shark mentioned, no other Pelagic fishes are
+known from the Arctic Ocean.</p>
+
+<p>We possess very little information about the Pelagic fish-fauna of
+the Southern oceans. So much only is certain, that the tropical forms
+<i>gradually</i> disappear; but it would be hazardous, in the present
+state of our knowledge, to state even approximately, the limits of
+the southward range of a single genus. Scarcely more is known about
+the appearance of types peculiar to the Southern temperate zone; for
+instance, the gigantic Shark (<i>Rhinodon</i>), representing the
+Northern Selache, near the coasts of South Africa, and the Scombroid
+genus, <i>Gastrochisma</i>, in the South Pacific.</p>
+
+<p>The largest of marine fishes, <i>Rhinodon</i>, <i>Selache</i>,
+<i>Carcharodon</i>, <i>Myliobatidæ</i>, <i>Thynnus</i>,
+<i>Xiphiidæ</i>, <i>Orthagoriscus</i>, belong to the Pelagic Fauna.
+Young fishes are frequently found in mid-ocean, which are the offspring
+of shore-fishes normally depositing their spawn near the coast. The
+manner, in which this fry passes into the open sea, is unknown; for it
+has not yet been ascertained whether it is carried by currents from
+the place where it was deposited originally, or whether shore-fishes
+sometimes spawn at a distance from the coast. We may remember that
+shore-fishes inhabit not only coasts but<span class="pagenum" id="Page_295">[295]</span> also submerged banks with
+some depth of water above, and that, by the action of the water,
+spawn deposited on these latter localities is very liable to be
+dispersed over wide areas of the ocean. Embryoes of at least some
+shore-fishes hatched under abnormal conditions seem to have an abnormal
+growth up to a certain period of their life, when they perish. The
+<i>Leptocephali</i> must be regarded as such abnormally developed
+fish (see p. 179). Fishes of a similar condition are the so-called
+Pelagic <i>Plagusiæ</i>, young Pleuronectoids, the origin of which is
+still unknown. As mentioned before, Flat-fishes, like all the other
+Anacanths, are otherwise not represented in the Pelagic fauna.</p>
+
+  <div class="figcenter" id="fig109" style="max-width: 336px">
+     <img
+    class="p1"   
+    src="images/fig109.jpg"
+     alt="">
+     <p class="p0 center smaller">Figs. 109 and 110.—<i>Antennarius candimaculatus</i>, a
+pelagic fish, from the Indian Ocean.</p>
+  </div>
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_296">[296]</span></p>
+
+<h2 class="smaller">CHAPTER XXI.<br>
+<span class="subhed">THE FISHES OF THE DEEP SEA.</span></h2></div>
+
+<p>The knowledge of the existence of deep-sea fishes is one of the
+recent discoveries of ichthyology. It is only about twenty years ago
+that, from the evidence afforded by the anatomical structure of a
+few singular fishes obtained in the North Atlantic, an opinion was
+expressed that these fishes inhabited great depths of the ocean, and
+that their organisation was specially adapted for living under the
+physical abyssal conditions. These fishes agreed in the character
+of their connective tissue, which was so extremely weak as to yield
+to, and to break under, the slightest pressure, so that the greatest
+difficulty is experienced to preserve their body in its continuity.
+Another singular circumstance was, that some of the specimens were
+picked up floating on the surface of the water, having met their
+deaths whilst engaged in swallowing or digesting another fish not much
+inferior or even superior in size to themselves.</p>
+
+<p>The first peculiarity was accounted for by the fact that, if those
+fishes really inhabited the great depths supposed, their removal from
+the enormous pressure under which they lived would be accompanied by
+such an expansion of gases within their tissues as to rupture them, and
+to cause a separation of the parts which had been held together by the
+pressure. The second circumstance was explained thus:—A raptatorial
+fish organised to live at a depth of between 500 and 800 fathoms seizes
+another usually inhabiting a depth of between 300 and 500 fathoms. In
+its struggles to escape,<span class="pagenum" id="Page_297">[297]</span> the fish seized, nearly as large or strong as
+the attacking fish, carries the latter out of its depth into a higher
+stratum, where the diminished pressure causes such an expansion of
+gases as to make the destroyer with its victim rise with increasing
+rapidity towards the surface, which they reach dead or in a dying
+condition. Specimens in this condition are not rarely picked up; and
+as, of course, comparatively few can by accident fall into the hands of
+naturalists, occurrences of the kind related must happen very often.</p>
+
+<p>Thus, the existence of fishes peculiarly adapted for the deep sea has
+been a fact maintained and admitted for some time in Ichthyology; and
+as the same genera and species were found at very distant parts of
+the ocean, it was further stated that those Deep-sea fishes were not
+limited in their range, and that, consequently, the physical conditions
+of the depths of the ocean must be the same or nearly the same over
+the whole globe. That Deep-sea fishes were not of a peculiar order,
+but chiefly modified forms of surface types, was another conclusion
+arrived at from the sporadic evidence collected during the period which
+preceded systematic deep-sea dredging.</p>
+
+<p>However, nothing was positively known as to the exact depths inhabited
+by those fishes until observations were made during the voyage of
+H.M.S. “Challenger.” The results obtained by this expedition afforded a
+surer and more extended basis for our knowledge of Deep-sea fishes.</p>
+
+<p>The physical conditions of the deep sea, which must affect the
+organisation and distribution of fishes, are the following:—</p>
+
+<p>1. Absence of sunlight. Probably the rays of the sun do not penetrate
+to, and certainly do not extend beyond, a depth of 200 fathoms,
+therefore we may consider this to be the depth where the Deep-sea
+fauna commences. Absence of light is, of necessity, accompanied by
+modifications of the organs of vision and by simplification of colours.</p>
+
+<p><span class="pagenum" id="Page_298">[298]</span></p>
+
+<p>2. The absence of sunlight is in some measure compensated for by the
+presence of phosphorescent light, produced by many marine animals, and
+also by numerous Deep-sea fishes.</p>
+
+<p>3. Depression and equality of the temperature. At a depth of 500
+fathoms the temperature of the water is already as low as 40° Fahr.,
+and perfectly independent of the temperature of the surface-water; and
+from the greatest depths upwards to about 1000 fathoms the temperature
+is uniformly but a few degrees above freezing-point. Temperature,
+therefore, ceases to offer an obstacle to the unlimited dispersal of
+Deep-sea fishes.</p>
+
+<p>4. The increased pressure by the water. The pressure of the atmosphere
+on the level of the sea amounts to fifteen pounds per square inch of
+the surface of the body of an animal; but the pressure amounts to a ton
+weight for every 1000 fathoms of depth.</p>
+
+<p>5. With the sunlight, vegetable life ceases in the depths of the sea.
+All Deep-sea fishes are therefore carnivorous; the most voracious
+feeding frequently on their own offspring, and the toothless kinds
+being nourished by the animalcules which live on the bottom, or which,
+“like a constant rain,” settle down from the upper strata towards the
+bottom of the sea.</p>
+
+<p>6. The perfect quiet of the water at great depths. The agitation of
+the water, caused by the disturbances of the air, does not extend
+beyond the depth of a few fathoms; below this surface-stratum there is
+no other movement except the quiet flow of ocean-currents, and near
+the bottom of the deep sea the water is probably in a state of almost
+entire quiescence.</p>
+
+<p>The effect upon fishes of the physical conditions described is
+clearly testified by the modification of one or more parts of their
+organisation, so that every Deep-sea fish may be recognised as such,
+without the accompanying positive evidence that it has been caught
+at a great depth; and <i>vice versa</i>, fishes reputed to have been
+obtained at a great depth, and not<span class="pagenum" id="Page_299">[299]</span> having any of the characteristics
+of the dwellers of the deep sea, must be regarded as surface-fishes.</p>
+
+<p>The most striking characteristic, found in many Deep-sea fishes,
+is in relation to the tremendous pressure under which they live.
+Their osseous and muscular systems are, as compared with the same
+parts of surface-fishes, very feebly developed. The bones have a
+fibrous, fissured, and cavernous texture; are light, with scarcely
+any calcareous matter, so that the point of a needle will readily
+penetrate them without breaking. The bones, especially the vertebræ,
+appear to be most loosely connected with one another; and it requires
+the most careful handling to prevent the breaking of the connective
+ligaments. The muscles, especially the great lateral muscles of the
+trunk and tail, are thin, the fascicles being readily separated from
+one another or torn, the connective tissue being extremely loose,
+feeble, or apparently absent. This peculiarity has been observed
+in the <i>Trachypteridæ</i>, <i>Plagyodus</i>, <i>Chiasmodus</i>,
+<i>Melanocetus</i>, <i>Saccopharynx</i>. But we cannot assume that
+it actually obtains whilst those fishes exist under their natural
+conditions. Some of them are most rapacious creatures which must be
+able to execute rapid and powerful movements to catch and overpower
+their prey; and for that object their muscular system, thin as its
+layers may be, must be as firm, and the chain of the segments of their
+vertebral column as firmly linked together as in surface-fishes.
+Therefore, it is evident that the change which the body of those fishes
+has undergone on their withdrawal from the pressure under which they
+live is a much aggravated form of the affection that is experienced
+by persons reaching great altitudes in their ascent of a mountain
+or in a balloon. In every living organism with an intestinal tract
+there are accumulations of free gases; and, moreover, the blood and
+other fluids, which permeate every part of the body, contain gases
+in solution. Under greatly diminished pressure these gases<span class="pagenum" id="Page_300">[300]</span> expand,
+so that, if the withdrawal from a depth is not an extremely slow and
+gradual process, the various tissues must be distended, loosened,
+ruptured; and what is a vigorous fish at a depth of 500 or more
+fathoms, appears at the surface as a loosely-jointed body which, if the
+skin is not of sufficient toughness, can only be kept together with
+difficulty. At great depths a fibrous osseous structure and a thin
+layer of muscles suffices to obtain the same results for which, at the
+surface, thickness of muscle and firm osseous or cartilaginous tissue
+are necessary.</p>
+
+<p>The muciferous system of many Deep-sea fishes is developed in an
+extraordinary degree. We find already in fishes which are comparatively
+little removed from the surface (that is to depths of 100–200
+fathoms), the lateral line much wider than in their congeners or
+nearest allies which live on the surface, as in <i>Trachichthys</i>,
+<i>Hoplostethus</i>, many <i>Scorpænidæ</i>. But in fishes inhabiting
+depths of 1000 and more fathoms, the whole muciferous system is
+dilated; it is especially the surface of the skull which is occupied by
+large cavities (<i>Macruridæ</i>, deep-sea <i>Ophidiidæ</i>), and the
+whole body seems to be covered with a layer of mucus. These cavities
+collapse and shrink in specimens which have been preserved in spirit
+for some time, but a re-immersion in water for a short time generally
+suffices to show the immense quantity of mucus secreted by them. The
+physiological use of this secretion is unknown; it has been observed to
+have phosphorescent properties in perfectly fresh specimens.</p>
+
+<p>The colours of Deep-sea fishes are extremely simple, their bodies
+being either black or silvery; in a few only are some filaments or the
+fin-rays of a bright scarlet colour. Among the black forms albinoes are
+not scarce.</p>
+
+<p>The organ of sight is the first to be affected by a sojourn in deep
+water. Even in fishes which habitually live at a depth of only 80
+fathoms, we find the eye of a proportionally larger<span class="pagenum" id="Page_301">[301]</span> size than in
+their representatives at the surface. In such fishes the eyes increase
+in size with the depth inhabited by them, down to the depth of 200
+fathoms, the large eyes being necessary to collect as many rays of
+light as possible. Beyond that depth small-eyed fishes as well as
+large-eyed occur, the former having their want of vision compensated
+for by tentacular organs of touch, whilst the latter have no such
+accessory organs, and evidently see only by the aid of phosphorescence.
+In the greatest depths blind fishes occur with rudimentary eyes and
+without special organs of touch.</p>
+
+<p>Many fishes of the deep sea are provided with more or less numerous,
+round, shining, mother-of-pearl-coloured bodies, imbedded in the skin.
+These so-called phosphorescent or luminous organs are either larger
+bodies of an oval or irregularly elliptical shape placed on the head,
+in the vicinity of the eye, or smaller round globular bodies arranged
+symmetrically in series along the side of the body and tail, especially
+near the abdominal profile, less frequently along the back. The former
+have not yet been anatomically examined. The number of pairs of the
+latter is in direct relation to that of the segments of the vertebral
+column, the muscular system, etc. (meta*-meres); and two kinds may be
+distinguished differing from each other in their anatomical structure.
+The organs of one kind consist of an anterior, biconvex, lens-like
+body, which is transparent during life, simple or composed of rods
+(<i>Chauliodus</i>); and of a posterior chamber which is filled with
+a transparent fluid, and coated with a dark membrane composed of
+hexagonal cells, or of rods arranged as in a retina. This structure
+is found in <i>Astronesthes</i>, <i>Stomias</i>, <i>Chauliodus</i>,
+etc. In the other kind the organ shows throughout a simply glandular
+structure, but apparently without an efferent duct (<i>Gonostoma</i>,
+<i>Scopelus</i>, <i>Maurolicus</i>, <i>Argyropelecus</i>). Branches
+of the spinal nerves run to each organ, and are distributed over the
+retina-like membrane or the glandular follicles. The former kind
+of<span class="pagenum" id="Page_302">[302]</span> organs are considered by some naturalists true organs of vision
+(accessory eyes), the function of the latter being left unexplained by
+them.</p>
+
+<p>Although, thus, these organs morphologically differ from each other,
+there is no doubt that the functions of all have some relation to the
+peculiar conditions of light under which the fishes provided with them
+live; these fishes being either deep-sea forms or nocturnal pelagic
+kinds. There are three possible hypotheses as to the function of these
+organs:—</p>
+
+<p>1. All the different kinds of organs are sensory, or, in other words,
+accessory eyes.</p>
+
+<p>2. Only the organs with a lenticular body are sensory, and those with a
+glandular structure produce and emit phosphorescent light.</p>
+
+<p>3. All are producers of light.</p>
+
+<p>There are very serious objections to adopting the first view.
+<i>Scopelus</i> and <i>Argyropelecus</i> possess not only perfectly
+developed, but even large eyes, specially adapted for a nocturnal
+life; and therefore accessory organs of vision must appear to be
+quite superfluous to them. On the other hand, in Deep-sea fishes
+without external eyes, which would seem to especially require these
+metameric organs of sense, they are invariably absent. And, finally,
+it is quite inconceivable that the glandular structures should have
+the faculty of conveying impressions of light to the nervous centre.
+The second supposition seems therefore to be nearer the truth; and
+is supported by the fact that the glandular organs of Scopeli have
+actually been observed to gleam with phosphorescent light, and by the
+obvious morphological similarity of the organs with a lenticular body
+and retina-like membrane to an organ of vision. We are, moreover,
+justified, from an <i>à priori</i> consideration, in supposing that
+in depths to which no sunlight descends, and which are illuminated by
+phosphorescent light only, peculiar organs of vision would have been<span class="pagenum" id="Page_303">[303]</span>
+developed. On the other hand, this supposition is opposed by the fact
+that many fishes which dwell in those abyssal depths are provided
+with large ordinary eyes (as the <i>Trachypteri</i>, the majority of
+<i>Macruridæ</i>), and, therefore, that the ordinary organ of vision is
+quite sufficient for seeing by phosphorescent light. Thus, whilst we
+must admit that those compound organs may prove to be organs of sense,
+we maintain at the same time that their morphological nature is not
+opposed to the belief that they too, like the glandular organs, are
+producers of light. It may be produced at the bottom of the posterior
+chamber, and emitted through the lenticular body in particular
+directions, with the same effect as light is sent through the convex
+glass of a “bull’s eye.” This hypothesis seems to be less bold than the
+other, which would require us to believe that vertebrate animals, with
+a nervous centre specialised for the reception of the impressions of
+the higher senses, should receive them through the spinal chord.</p>
+
+<div class="blockquot">
+
+<p>[See <i>Ussow</i>, “Ueber den Bau der sogenannten
+augenaehnlichen Flecken einiger Knochenfische.” St. Petersburg,
+Bullet. 1879.]</p>
+</div>
+
+<p>Whenever we find in a fish long delicate filaments, developed in
+connection with the fins or the extremity of the tail, we may
+conclude that it is an inhabitant of still water and of quiet habits.
+Many deep-sea fishes (<i>Trachypteridæ</i>, <i>Macruridæ</i>,
+<i>Ophidiidæ</i>, <i>Bathypterois</i>) are provided with such
+filamentous prolongations, the development of which is perfectly in
+accordance with their sojourn in the absolutely quiet waters of abyssal
+depths.</p>
+
+<p>Some of the raptatorial Deep-sea fishes have a stomach so distensible
+and capacious that it can receive a fish of twice or thrice the
+bulk of the destroyer (<i>Melanocetus</i>, <i>Chiasmodus</i>,
+<i>Saccopharynx</i>). Deglutition is performed in them not by means of
+the muscles of the pharynx, as in other fishes, but by the independent
+and alternate action of the<span class="pagenum" id="Page_304">[304]</span> jaws, as in Snakes. These fishes cannot
+be said to swallow their food, but rather draw themselves over their
+victim, in the fashion of an <i>Actinia</i>.</p>
+
+<p>Before the voyage of H.M.S. “Challenger,” scarcely thirty Deep-sea
+fishes were known. This number is now much increased by the discovery
+of many new species and genera; but, singularly, no new types of
+families were discovered: nothing but what might have been expected
+from our previous knowledge of this group of fishes. Modifications of
+certain organs, perfectly novel, and of the greatest interest, were
+found, as we shall see in the “Systematic Part;” but the most important
+results of this voyage are that the general character of the abyssal
+fish-fauna, the abundance of fishes, and the exact depths to which
+fishes may descend, have been ascertained.</p>
+
+<p>However, the statements of the depths at which the fishes collected by
+the “Challenger” were taken cannot be received without some critical
+examination of each individual species. No precaution was taken to
+keep the mouth of the dredge closed during its descent or ascent,
+and therefore it is quite within the limits of probability that
+sometimes fishes were accidentally enclosed within the dredge, whilst
+it was traversing the surface strata. And this has happened more
+than once; for it is quite certain that common surface fishes like
+<i>Sternoptyx</i> and <i>Astronestles</i>, never ranged to a depth of
+2500 fathoms. On the other hand, the majority of the fishes obtained
+offer sufficient evidence from their own organisation that they live
+on the bottom, and are unable to support themselves in the water at a
+certain distance from the bottom or surface; and, consequently, that
+they actually were obtained at the depth to which the dredge descended.</p>
+
+<p>As far as the observations go at present, no distinct bathymetrical
+regions, which would be characterised by peculiar forms, can be
+defined. The depths from 200 to<span class="pagenum" id="Page_305">[305]</span> 600 fathoms are inhabited by
+numerous forms, still strongly reminding us of surface types. To this
+fauna belong the few Chondropterygians of the deep sea, a Sebastes
+and Setarches, a Beryx and Polymixia, a Cottus, etc.; but they are
+associated with many others which descend to the greatest depths.
+And before anything like a division into bathymetrical zones can be
+attempted, the observations of the “Challenger” expedition must be
+confirmed and supplemented by other series of similar systematic
+observations. One of the most startling conclusions at which we would
+have to arrive from the “Challenger” observations is, that some of the
+species of Deep-sea fishes would range from a depth of some 300 fathoms
+down to one of 2000 fathoms; or, in other words, that a fish which
+has once attained in its organisation to that modification by which
+it is enabled to exist under the pressure of half a ton, can easily
+accommodate itself to one of two tons or more,—a conclusion which is
+not in accordance with anatomical facts, and which must be confirmed by
+other observations before we can adopt it. But if the vertical range of
+Deep-sea fishes is actually as it appears from the “Challenger” lists,
+then there is no more distinct vertical than horizontal distribution of
+Deep-sea fishes.</p>
+
+<p>The greatest depth reached hitherto by a dredge in which fishes were
+enclosed is 2900 fathoms. But the specimens thus obtained belong to
+a species (<i>Gonostoma microdon</i>), which seems to be extremely
+abundant in upper strata of the Atlantic and Pacific, and were
+therefore most likely caught by the dredge in its ascent. The next
+greatest depth, viz., 2750 fathoms, must be accepted as one at which
+fishes undoubtedly do live; the fish obtained from this depth of the
+Atlantic, <i>Bathyophis ferox</i>, showing by its whole habit that it
+is a form living on the bottom of the ocean.</p>
+
+<p>The fish-fauna of the deep sea is composed chiefly of forms or
+modifications of forms which we find represented at<span class="pagenum" id="Page_306">[306]</span> the surface in the
+cold and temperate zones, or which appear as nocturnal pelagic forms.
+The Chondropterygians are few in number, not descending to a depth of
+more than 600 fathoms. The Acanthopterygians, which form the majority
+of the coast and surface faunas, are also scantily represented; genera
+identical with surface types are confined to the same inconsiderable
+depths as the Chondropterygians, whilst those Acanthopterygians which
+are so much specialised for the life in the deep sea as to deserve
+generic separation, range from 200 to 2400 fathoms. Three distinct
+families of Acanthopterygians belong to the deep-sea fauna, viz.
+<i>Trachypteridæ</i>, <i>Lophotidæ</i>, and <i>Notacanthidæ</i>; they
+respectively consist of three, one, or two genera only.</p>
+
+<p><i>Gadidæ</i>, <i>Ophidiidæ</i>, and <i>Macruridæ</i> are very
+numerous, ranging through all depths; they constitute about one-fourth
+of the whole deep-sea fauna.</p>
+
+<p>Of <i>Physostomi</i>, the families of <i>Sternoptychidæ</i>,
+<i>Scopelidæ</i>, <i>Stomiatidæ</i>, <i>Salmonidæ</i>,
+<i>Bathythrissidæ</i>, <i>Alepocephalidæ</i>, <i>Halosauridæ</i>,
+and <i>Murænidæ</i> are represented. Of these the <i>Scopeloids</i>
+are the most numerous, constituting nearly another fourth of
+the fauna. <i>Salmonidæ</i> are scarce, with three small genera
+only. <i>Bathythrissidæ</i> include one species only, which is
+probably confined in its vertical as well as horizontal range; it
+occurs at a depth of about 350 fathoms in the sea of Japan. The
+<i>Alepocephalidæ</i> and <i>Halosauridæ</i>, known before the
+“Challenger” expedition from isolated examples only, prove to be true,
+widely-spread, deep-sea types. Eels are well represented, and seem to
+descend to the greatest depths.</p>
+
+<p><i>Myxine</i> has been obtained from a depth of 345 fathoms.</p>
+
+<p>It will be useful to append a complete list of Deep-sea fishes, with
+the depths as ascertained by the dredgings of the “Challenger:”—</p>
+
+<p><span class="pagenum" id="Page_307">[307]</span></p>
+
+
+<p class="center"><i>List of Deep-sea Fishes.</i></p>
+
+<table class="smaller">
+  <tr>
+    <td class="cht"></td>
+    <td class="ctr">Fathoms.</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Chondropterygians—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Raja</td>
+    <td class="right3">565</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Scyllium</td>
+    <td class="right3">400</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Centroscyllium</td>
+    <td class="right3">245</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Centrophorus</td>
+    <td class="right3">345–500</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Acanthopterygians—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Pomatomus</td>
+    <td class="right3">(? down to) 200</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Sebastes</td>
+    <td class="right3">275</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Setarches</td>
+    <td class="right3">215</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Beryx</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Melamphaes</td>
+    <td class="right3">(? beyond) 200</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Polymixia</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Nealotus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Nesiarchus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Aphanopus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Euoxymetopon</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Lepidopus</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Gempylus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Anomalops</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="chtiii">? Antigonia</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Diretmus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Cottus</td>
+    <td class="right3">565</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathydraco</td>
+    <td class="right3">1260</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Oneirodes</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Melanocetus johnsonii</td>
+    <td class="right3">1850</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;bispinosus</td>
+    <td class="right3">360</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Himantolophus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Chaunax</td>
+    <td class="right3">215</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Ceratias</td>
+    <td class="right3">2400</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Halieutichthys</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Dibranchus</td>
+    <td class="right3">360</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Trachypteridæ</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Lophotes</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Notacanthus rissoanus</td>
+    <td class="right3">1875</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;bonapartii</td>
+    <td class="right3">400<span class="pagenum" id="Page_308">[308]</span></td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Anacanthini—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Melanonus</td>
+    <td class="right3">1975</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Lotella marginata</td>
+    <td class="right3">120–345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Physiculus</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Uraleptus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Læmonema</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Haloporphyrus australis</td>
+    <td class="right3">55–70</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;lepidion</td>
+    <td class="right3">345–600</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;rostratus</td>
+    <td class="right3">600–1375</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Chiasmodus niger</td>
+    <td class="right3">1500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Sirembo grandis</td>
+    <td class="right3">1875</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&ensp;„&emsp;&ensp;&nbsp;macrops</td>
+    <td class="right3">375</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&ensp;„&emsp;&ensp;&nbsp;messieri</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&ensp;„&emsp;&ensp;&nbsp;ocellatus</td>
+    <td class="right3">350</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&ensp;„&emsp;&ensp;&nbsp;brachysoma</td>
+    <td class="right3">350</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Acanthonus armatus</td>
+    <td class="right3">1075</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Typhlonus nasus</td>
+    <td class="right3">2440</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Aphyonus gelatinosus</td>
+    <td class="right3">1400</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Rhinonus ater</td>
+    <td class="right3">2150</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathynectes laticeps</td>
+    <td class="right3">2500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&ensp;compressus</td>
+    <td class="right3">1075–2500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&ensp;gracilis</td>
+    <td class="right3">1400</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Pteridium</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Macrurus (12 species)</td>
+    <td class="right3">120–700</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Coryphænoides norvegicus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;serratus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;nasutus</td>
+    <td class="right3">345–565</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;villosus</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;rudis</td>
+    <td class="right3">500–650</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;æqualis</td>
+    <td class="right3">600</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;crassiceps</td>
+    <td class="right3">520–650</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;microlepis</td>
+    <td class="right3">215</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;murrayi</td>
+    <td class="right3">1100</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;serrulatus</td>
+    <td class="right3">700</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;filicauda</td>
+    <td class="right3">1800–2650</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;variabilis</td>
+    <td class="right3">1375–2425</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;affinis</td>
+    <td class="right3">1900<span class="pagenum" id="Page_309">[309]</span></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;carinatus</td>
+    <td class="right3">500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;longifilis</td>
+    <td class="right3">565</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;altipinnis</td>
+    <td class="right3">565–1875</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;asper</td>
+    <td class="right3">500–1875</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;leptolepis</td>
+    <td class="right3">350–2050</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;sclerorhynchus</td>
+    <td class="right3">1090</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&emsp;denticulatus</td>
+    <td class="right3">275–520</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Malacocephalus</td>
+    <td class="right3">350</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathygadus cottoides</td>
+    <td class="right3">520–700</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&nbsp;multifilis</td>
+    <td class="right3">500</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Sternoptychidæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Argyropelecus</td>
+    <td class="right">1127 [?]</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Sternoptyx</td>
+    <td class="right">0–2500 [?]</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Polyipnus</td>
+    <td class="right3">255</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Gonostoma denudatum</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;microdon</td>
+    <td class="right">500–2900 [?]</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;elongatum</td>
+    <td class="right3">360–800</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;gracile</td>
+    <td class="right3">345–2425</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Chauliodus</td>
+    <td class="right3">565–2560</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Scopelidæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathysaurus ferox</td>
+    <td class="right3">1100</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&nbsp;mollis</td>
+    <td class="right3">1875–2385</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathypterois longifilis</td>
+    <td class="right3">520–630</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;longipes</td>
+    <td class="right3">2650</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;quadrifilis</td>
+    <td class="right3">500–770</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;longicauda</td>
+    <td class="right3">2550</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Chlorophthalmus agassizii</td>
+    <td class="right3">215</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;&emsp;„&emsp;&emsp;&ensp;&nbsp;nigripinnis</td>
+    <td class="right3">120</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;&emsp;„&emsp;&emsp;&ensp;&nbsp;gracilis</td>
+    <td class="right3">1100–1425</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Scopelus engraulis</td>
+    <td class="right3">255</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;antarcticus</td>
+    <td class="right3">1950</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;antarcticus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;mizolepis</td>
+    <td class="right3">800</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;dumerilii</td>
+    <td class="right3">215</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;macrolepidotus</td>
+    <td class="right3">520–630</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;crassiceps</td>
+    <td class="right3">675–1550</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;macrostoma</td>
+    <td class="right3">2350–2425</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;„&emsp;&ensp;microps</td>
+    <td class="right3">1375</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Odontostomus hyalinus</td>
+    <td class="right3"><span class="pagenum" id="Page_310">[310]</span></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Odontostomus humeralis</td>
+    <td class="right3">500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Nannobrachium nigrum</td>
+    <td class="right3">500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Ipnops murrayi</td>
+    <td class="right3">1600–2150</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Paralepis</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Sudis</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Plagyodus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Stomiatidæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Astronesthes niger</td>
+    <td class="right">2500 [?]</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Stomias boa</td>
+    <td class="right3">450–1800</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&ensp;„&emsp;&ensp;barbatus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&ensp;„&emsp;&ensp;ferox</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Echiostoma barbatum</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;micripnus</td>
+    <td class="right3">2150</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;microdon</td>
+    <td class="right3">2440</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Malacosteus niger</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;indicus</td>
+    <td class="right3">500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathyophis ferox</td>
+    <td class="right3">2750</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Salmonidæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Argentina</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Microstoma</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathylagus antarcticus</td>
+    <td class="right3">1950</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&nbsp;atlanticus</td>
+    <td class="right3">2040</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Bathythrissidæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathythrissa dorsalis</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Alepocephalidæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Alepocephalus rostratus</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;„&emsp;&emsp;&ensp;&nbsp;niger</td>
+    <td class="right3">1400</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Platytroctes apus</td>
+    <td class="right3">1500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Bathytroctes microlepis</td>
+    <td class="right3">1090</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;rostratus</td>
+    <td class="right3">675</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&ensp;„&emsp;&emsp;&ensp;macrolepis</td>
+    <td class="right3">2150</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Xenodermichthys</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Halosauridæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Halosaurus owenii</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&nbsp;affinis</td>
+    <td class="right3">565</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&nbsp;macrochir</td>
+    <td class="right3">1090–1375</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&nbsp;mediorostris</td>
+    <td class="right3">700</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&nbsp;rostratus</td>
+    <td class="right3">2750<span class="pagenum" id="Page_311">[311]</span></td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Murænidæ—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Nemichthys scolopacea</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&nbsp;„&emsp;&emsp;&ensp;infans</td>
+    <td class="right3">500–2500</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Cyema atrum</td>
+    <td class="right3">1500–1800</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Saccopharynx</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Synaphobranchus pinatus</td>
+    <td class="right3">345–1200</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;&ensp;„&emsp;&emsp;&emsp;&ensp;bathybius</td>
+    <td class="right3">1875–2050</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;&ensp;„&emsp;&emsp;&emsp;&ensp;brevidorsalis</td>
+    <td class="right3">1075–1375</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">&emsp;&emsp;&emsp;&ensp;„&emsp;&emsp;&emsp;&ensp;affinis</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Nettastoma parviceps</td>
+    <td class="right3">345</td>
+    </tr>
+
+  <tr>
+    <td class="cht smcap">Cyclostomata—</td>
+    <td class="right3"></td>
+    </tr>
+
+  <tr>
+    <td class="cht3">Myxine australis</td>
+    <td class="right3">345</td>
+    </tr>
+</table>
+
+  <div class="figcenter" id="fig111" style="max-width: 501px">
+     <img
+    class="p1"   
+    src="images/fig111.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 111.—<i>Chiasmodus niger</i>; obtained in the
+North Atlantic at a depth of 1500 fathoms; the specimen has swallowed a
+large Scopelus (<i>s</i>); <i>o</i>, ventral fin.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_312">[312]</span></p>
+
+<h2>SYSTEMATIC AND DESCRIPTIVE PART.</h2>
+</div>
+
+  <div class="figcenter">
+    <img
+    class="p0" 
+    src="images/a003_deco.jpg"
+    alt="">
+  </div>
+
+
+
+<p>The Class of Fishes is divided into four sub-classes:—</p>
+
+<p>I. <span class="smcap">Palæichthyes</span>.—Heart with a contractile conus arteriosus;
+intestine with a spiral valve; optic nerves non-decussating, or only
+partially decussating.</p>
+
+<p>II. <span class="smcap">Teleostei</span>.—Heart with a non-contractile bulbus
+arteriosus; intestine without spiral valve; optic nerves decussating.
+Skeleton ossified, with completely separated vertebræ.</p>
+
+<p>III. <span class="smcap">Cyclostomata</span>.—Heart without bulbus arteriosus; intestine
+simple. Skeleton cartilaginous and notochordal. One nasal aperture
+only. No jaws; mouth surrounded by a circular lip.</p>
+
+<p>IV. <span class="smcap">Leptocardii</span>.—Heart replaced by pulsating sinuses;
+intestine simple. Skeleton membrano-cartilaginous and notochordal. No
+skull; no brain.</p>
+
+
+<h3 class="smaller">FIRST SUB-CLASS: PALÆICHTHYES.</h3>
+
+<p><i>Heart with a contractile conus arteriosus;<a id="FNanchor_30" href="#Footnote_30" class="fnanchor">[30]</a> intestine with a
+spiral valve;<a id="FNanchor_31" href="#Footnote_31" class="fnanchor">[31]</a> optic nerves non-decussating, or only partially
+decussating;<a id="FNanchor_32" href="#Footnote_32" class="fnanchor">[32]</a> skeleton cartilaginous or osseous.</i></p>
+
+<p>This sub-class comprises the Sharks and Rays, and the Ganoid fishes.
+Although based upon a singular concurrence of most important
+characters, its members exhibit as great a diversity of form, and as
+manifold modifications in the remainder<span class="pagenum" id="Page_313">[313]</span> of their organisation as the
+<i>Teleostei</i>. The <i>Palæichthyes</i> stand to the <i>Teleostei</i>
+in the same relation as the Marsupials to the Placentalia.
+Geologically, as a sub-class, they were the predecessors of Teleosteous
+fishes; and it is a remarkable fact that all those modifications which
+show an approach of the ichthyic type to the Batrachians are found in
+this sub-class. We divide it into two orders: <i>Chondropterygii</i>
+and <i>Ganoidei</i>.</p>
+
+
+<h4 class="smaller">FIRST ORDER: CHONDROPTERYGII.</h4>
+
+<p><i>Skeleton cartilaginous. Body with medial and paired fins, the
+hinder pair abdominal. Vertebral column generally heterocercal, the
+upper lobe of the caudal fin produced. Gills attached to the skin by
+the outer margin, with several intervening gill-openings: rarely one
+external gill-opening only. No gill-cover. No air-bladder. Two, three,
+or more series of valves in the conus arteriosus. Ova large and few
+in number,<a id="FNanchor_33" href="#Footnote_33" class="fnanchor">[33]</a> impregnated and, in some species, developed within a
+uterine cavity. Embryo with deciduous external gills.<a id="FNanchor_34" href="#Footnote_34" class="fnanchor">[34]</a> Males with
+intromittent organs attached to the ventral fins.<a id="FNanchor_35" href="#Footnote_35" class="fnanchor">[35]</a></i></p>
+
+<p>This order, for which, also, the name <i>Elasmobranchii</i> has
+been proposed (by Bonaparte), comprises the Sharks and Rays and
+Chimæras, and is divided into two suborders: <i>Plagiostomata</i> and
+<i>Holocephala</i>.</p>
+
+
+<h5 class="smaller">FIRST SUB-ORDER: PLAGIOSTOMATA.</h5>
+
+<p><i>From five to seven gill-openings. Skull with a suspensorium and the
+palatal apparatus detached. Teeth numerous.</i></p>
+
+<p>The Plagiostomes differ greatly among each other with regard to the
+general form of their body: in the Sharks or <i>Selachoidei</i> the
+body is elongate, more or less cylindrical, gradually passing into the
+tail; their gill-openings are lateral. In the Rays, or <i>Batoidei</i>,
+the gill-openings are always placed<span class="pagenum" id="Page_314">[314]</span> on the abdominal aspect of the
+fish; the body is depressed, and the trunk, which is surrounded by the
+immensely developed pectoral fins, forms a broad flat disk, of which
+the tail appears as a thin and slender appendage. Spiracles are always
+present; the number of gill-openings is constantly five; no anal fin;
+dorsal fins, if present, situated on the tail. However, some of the
+Rays approach the Sharks in having the caudal portion less abruptly
+contracted behind the trunk.</p>
+
+<p>Fossil Plagiostomes are very numerous in all formations. Some of
+the earliest determinable fish remains are believed to be, or are,
+derived from Plagiostomes. Those which can be referred to any of
+the following families will be mentioned subsequently: but there
+are others, especially fin-spines, which leave us in doubt to
+which group of Plagiostomes their owners had any affinity, thus
+<i>Onchus</i> from the upper Silurian, continuing to carboniferous
+formations; <i>Dimeracanthus</i>, <i>Homocanthus</i>, from the
+Devonian; <i>Oracanthus</i>, <i>Gyracanthus</i>, <i>Tristychius</i>,
+<i>Astroptychius</i>, <i>Ptychacanthus</i>, <i>Sphenacanthus</i>,
+etc., from carboniferous formations; <i>Leptacanthus</i>, from
+the coal to the Oolite; <i>Cladacanthus</i>, <i>Cricacanthus</i>,
+<i>Gyropristis</i>, and <i>Lepracanthus</i>, from the coal
+measures; <i>Nemacanthus</i>, <i>Liacanthus</i>, from the Trias;
+<i>Astracanthus</i>, <i>Myriacanthus</i>, <i>Pristacanthus</i>, from
+the Jurassic group.</p>
+
+
+<h6>A. <span class="smcap">Selachoidei: Sharks.</span></h6>
+
+<p>The elongate cylindrical body, generally terminating in a more or
+less pointed snout, and passing into a powerful and flexible tail,
+blade-like at its extremity, gives to the Sharks a most extraordinary
+power of swimming, with regard to endurance as well as rapidity of
+motion. Many, especially the larger kinds, inhabit the open ocean,
+following ships for weeks, or pursuing shoals of fishes in their
+periodical migrations. Other large-sized sharks frequent such parts
+of the coast as<span class="pagenum" id="Page_315">[315]</span> offer them abundance of food; whilst the majority of
+the smaller kinds are shore fishes, rarely leaving the bottom, and
+sometimes congregating in immense numbers. The movements of sharks
+resemble in some measure those of snakes, their flexible body being
+bent in more than one curve when moving.</p>
+
+<p>Sharks are most numerous in the seas between the Tropics, and become
+scarcer beyond, a few only reaching the Arctic circle; it is not known
+how far they advance southwards towards the Antarctic region. Some
+species enter fresh waters, and ascend large rivers, like the Tigris
+or Ganges, to a considerable distance. The pelagic as well as the
+shore species have a wide geographical range. Very few descend to a
+considerable depth, probably not exceeding 500 fathoms. There are about
+140 different species known.</p>
+
+<p>Sharks have no scales like those of other fishes; their integuments
+are covered with calcified papillæ which, under the microscope, show a
+structure similar to that of teeth. If the papillæ are small, pointed,
+and close set, the skin is called “shagreen;” rarely they are larger,
+appearing as bucklers or spines, of various sizes.</p>
+
+<p>These fishes are exclusively carnivorous, and those armed with powerful
+cutting teeth are the most formidable tyrants of the ocean. They have
+been known to divide the body of a man in two at one bite, as if by
+the sweep of a sword. Some of the largest sharks, however, which
+are provided with very small teeth, are almost harmless, feeding on
+small fishes only or marine invertebrates. Others, particularly of
+the smaller kinds, commonly called “Dog-fishes,” have short or obtuse
+teeth, and feed on shells or any other animal substance. Sharks scent
+their food from a distance, being readily attracted by the smell of
+blood or decomposing bodies.</p>
+
+<p>In China and Japan, and many other eastern countries, the smaller kinds
+of sharks are eaten. Sharks’ fins form in<span class="pagenum" id="Page_316">[316]</span> India and China a very
+important article of trade, the Chinese preparing from them gelatine,
+and using the better sorts for culinary purposes. The fins are obtained
+not exclusively from Sharks but also from Rays, and assorted in two
+kinds, viz. “white and black.” The white consist exclusively of the
+dorsal fins, which are on both sides of the same uniform light colour,
+and reputed to yield more gelatine than the other fins. The pectoral,
+ventral, and anal fins pass under the denomination of black fins; the
+caudal fin is not used. One of the principal places where shark fishery
+is practised as a profession is Kurrachee. Dr. Buist, writing in 1850
+(“Proc. Zool. Soc.” 1850, p. 100), states that there are thirteen
+large boats, with crews of twelve men each, constantly employed in
+this pursuit; that the value of the fins sent to the market varies
+from 15,000 to 18,000 rupees; that one boat will sometimes capture at
+a draught as many as one hundred sharks of various sizes; and that the
+number total of sharks captured during the year amounts probably to not
+less than 40,000. Large quantities are imported from the African coast
+and the Arabian Gulf, and various ports on the coast of India. In the
+year 1845–46, 8770 cwt. of sharks’ fins were exported from Bombay to
+China.</p>
+
+
+<h6 class="smcap">First Family—Carchariidæ.</h6>
+
+<p><i>Eye with a nictitating membrane. Mouth crescent-shaped, inferior.
+Anal fin present. Two dorsal fins, the first opposite to the space
+between pectoral and ventral fins, without spine in front.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Carcharias.</span>—Snout produced in the longitudinal axis
+of the body; mouth armed with a series of large flat triangular
+teeth, which have a smooth cutting or serrated edge. Spiracles
+absent. A transverse pit on the back of the tail, at the root of
+the caudal fin.</p>
+</div>
+
+<p>This genus comprises the true Sharks, common in the<span class="pagenum" id="Page_317">[317]</span> tropical, but
+less so in the temperate seas. Between thirty and forty different
+species have been distinguished, of which one of the most common is
+the “Blue Shark” (<i>Carcharias glaucus</i>). Individuals of from
+twelve to fifteen feet are of very common occurrence, but some of
+the species attain a much larger size, and a length of 25 and more
+feet. Fishes of this genus or of closely allied genera (<i>Corax</i>,
+<i>Hemipristis</i>) are not uncommon in the chalk and tertiary
+formations.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Galeocerdo.</span>—Teeth large, flat, triangular, oblique,
+serrated on both edges, with a deep notch on the outer margin.
+Spiracles small. A pit on the tail, above and below, at the root
+of the caudal fin. Two notches on the under caudal border, one
+of them at the end of the spine.</p>
+</div>
+
+  <div class="figcenter" id="fig112" style="max-width: 385px">
+     <img
+    class="p1"   
+    src="images/fig112.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 112.—Dentition of the Blue Shark (Carcharias
+glaucus); the single teeth are of the natural size.</p>
+  </div>
+
+<p>Three species, of which one (<i>G. arcticus</i>) is confined to<span class="pagenum" id="Page_318">[318]</span> the
+arctic and sub-arctic oceans. The others inhabit temperate and tropical
+seas, and all attain to a very large size.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Galeus.</span>—Snout produced in the longitudinal axis of the
+body; teeth equal in both jaws, rather small, flat, triangular,
+oblique, serrated and with a notch. Spiracles small. No pit at
+the commencement of the caudal fin, which has a single notch on
+its lower margin.</p>
+</div>
+
+<p>These are small sharks, commonly called “Tope.” The species found on
+the British coast is spread over nearly all the temperate and tropical
+seas, and is common in California and Tasmania. It lives on the bottom,
+and is very troublesome to fishermen by constantly taking away bait or
+driving away the fishes which they desire to catch.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Zygæna.</span>—The anterior part of the head is broad,
+flattened, and produced into a lobe on each side, the extremity
+of which is occupied by the eye. Caudal fin with a single notch
+at its lower margin. A pit at the root of the caudal fin.
+Spiracles none. Nostrils situated on the front edge of the head.</p>
+</div>
+
+<p>The “Hammerheads,” or Hammerheaded Sharks, have a dentition very
+similar to that of <i>Carcharias</i>, and although they do not
+attain to the same large size, they belong to the most formidable
+fishes of the ocean. The peculiar form of their head is quite unique
+among fishes; young examples have the lateral extension of the skull
+much less developed than adults. Five species are known, which are
+most abundant in the tropics. By far the most common is <i>Zygæna
+malleus</i>, which occurs in nearly all tropical and sub-tropical seas.
+Specimens of this species may be often seen ascending from the clear
+blue depths of the ocean like a great cloud. Cantor found in a female,
+nearly 11 feet long, thirty-seven embryons.—Hammerheads have lived
+from the cretaceous epoch.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Mustelus.</span>—The second dorsal fin is not much smaller
+than the first. No pit at the root of the caudal, which is
+without distinct lower lobe. Snout produced in the longitudinal
+axis<span class="pagenum" id="Page_319">[319]</span> of the body. Spiracles small, behind the eyes. Teeth
+small, numerous, similar in both jaws, obtuse, or with very
+indistinct cusps, arranged like pavement.</p>
+</div>
+
+<p>The “Hounds” are small Sharks, abundant on the coasts of all the
+temperate and tropical seas; two of the five species known occur on
+the coasts of Europe, viz. <i>M. lævis</i> and <i>M. vulgaris</i>.
+Closely allied as these two species are, they yet show a most singular
+difference, viz. that a placenta is developed in the uterus for the
+attachment of the embryo in <i>M. lævis</i> (the Γαλεὁς λεȋος of
+Aristotle, to whom this fact was already known); whilst the embryons
+of <i>M. vulgaris</i> are developed without such placenta (see <i>J.
+Müller</i>, “Abhandl. Ak. Wiss.” Berl. 1840). The Hounds are bottom
+fish, which feed principally on shells, crustaceans, and decomposing
+animal substances.</p>
+
+<hr class="tb">
+
+<p>Several other genera belong to the family Carchariidæ, but it will be
+sufficient to mention their names:—<i>Hemigaleus</i>, <i>Loxodon</i>,
+<i>Thalassorhinus</i>, <i>Triænodon</i>, <i>Leptocarcharias</i>, and
+<i>Triacis</i>.</p>
+
+
+<h6 class="smcap">Second Family—Lamnidæ.</h6>
+
+<p><i>Eye without nictitating membrane. Anal fin present. Two dorsal fins;
+the first opposite to the space between pectoral and ventral fins,
+without spine in front. Nostrils not confluent with the mouth which is
+inferior. Spiracles absent or minute.</i></p>
+
+<p>All the fishes of this family attain to a very large size, and
+are pelagic. But little is known of their reproduction. The first
+appearance of this family is indicated by <i>Carcharopsis</i>, a
+genus from carboniferous formations, the teeth of which differ from
+those of <i>Carcharodon</i> only by having a broad fold at the base.
+In the chalk and tertiary formations almost all the existing genera
+are represented; and, besides, <i>Oxytes</i>, <i>Sphenodus</i>,
+<i>Gomphodus</i>, and <i>Ancistrodon</i>, which are known<span class="pagenum" id="Page_320">[320]</span> from teeth
+only, have been considered generically distinct from the living
+Porbeagles.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lamna (Oxyrhina).</span>—The second dorsal and anal are very
+small. A pit at the root of the caudal, which has the lower lobe
+much developed. Side of the tail with a prominent longitudinal
+keel. Mouth wide. Teeth large, lanceolate, not serrated,
+sometimes with additional basal cusps. On each side of the upper
+jaw, at some distance from the symphysis, there is one or two
+teeth conspicuously smaller than the others. Gill-openings very
+wide. Spiracles minute.</p>
+</div>
+
+  <div class="figcenter" id="fig113" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig113.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 113.—Upper and lower tooth of Lamna.</p>
+  </div>
+
+<p>Of the “Porbeagles,” three species have been described, of which the
+one occurring in the North Atlantic, and frequently straying to the
+British coasts (<i>L. cornubica</i>), is best known. It attains to a
+length of ten feet, and feeds chiefly on fishes; its lanceolate teeth
+are not adapted for cutting, but rather for seizing and holding its
+prey, which it appears to swallow whole. According to Pennant it is
+viviparous; only two embryoes were found in the female which came under
+his observation. Haast has found this species also off the coast of New
+Zealand.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Carcharodon.</span>—The second dorsal and anal are very
+small. Pit at the root of the caudal, which has the lower
+lobe well developed. Side of the tail with a prominent
+longitudinal keel. Mouth wide. Teeth large, flat, erect,
+regularly triangular, serrated. On each side of the upper jaw,
+at some distance from the symphysis, there is one or two teeth
+conspicuously smaller than the others. Gill-openings wide.</p>
+</div>
+
+<p>One species only is known (<i>C. rondeletii</i>), which is the most
+formidable of all Sharks. It is strictly pelagic; and appears to occur
+in all tropical and sub-tropical seas. It is known to attain to a
+length of 40 feet. The tooth figured here, of the natural size, is
+taken from a jaw 20 inches wide in its transverse diameter (inside
+measure), each half of the<span class="pagenum" id="Page_321">[321]</span> mandible measuring 22 inches.<a id="FNanchor_36" href="#Footnote_36" class="fnanchor">[36]</a> The whole
+length of the fish was 36½ feet.</p>
+
+<p>Carcharodon teeth are of very common occurrence in various tertiary
+strata, and have been referred to several species, affording ample
+evidence that this type was much more numerously represented in that
+geological epoch than in the recent fauna. Some individuals attained to
+an immense size, as we may judge from teeth found in the Crag, which
+are 4 inches wide at the base, and 5 inches long, measured along their
+lateral margin. The naturalists of the “Challenger” expedition have
+made the highly interesting discovery that teeth of similar size are
+of common occurrence in the ooze of the Pacific, between Polynesia and
+the west coast of America. As we have no record of living individuals
+of that bulk having been observed, the gigantic species to which these
+teeth belonged must have become extinct within a comparatively recent
+period. Nothing is known of the anatomy, habits, and reproduction of
+the surviving species, and no opportunity should be lost of obtaining
+information on this Shark.</p>
+
+  <div class="figcenter" id="fig114" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig114.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 114.—Tooth of Carcharodon rondeletii.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Odontaspis.</span>—The second dorsal and anal are not
+much smaller than the first dorsal. No pit at the root of
+the caudal. Side of the tail without keel. Mouth wide. Teeth
+large, awl-shaped, with one or two small cusps at the base.
+Gill-openings of moderate width.</p>
+</div>
+
+<p>Large Sharks from tropical and temperate seas; two species.</p>
+
+<p><span class="pagenum" id="Page_322">[322]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Alopecias.</span>—The second dorsal and anal very small.
+Caudal fin of extraordinary length, with a pit at its root.
+No keel on the side of the tail. Mouth and gill-openings of
+moderate width. Teeth equal in both jaws, of moderate size,
+flat, triangular, not serrated.</p>
+</div>
+
+<p>This genus consists of one species only, which is known by the name of
+“Fox-shark” or “Thresher.” It is the most common of the larger kinds
+of Sharks which occur on the British coasts; and seems to be equally
+common in other parts of the Atlantic and Mediterranean, as well as on
+the coasts of California and New Zealand. It attains to a length of
+fifteen feet, of which the tail takes more than one half; and is quite
+harmless to man. It follows the shoals of Herrings, Pilchards, and
+Sprats in their migrations, destroying incredible numbers. When feeding
+it uses the long tail in splashing the surface of the water, whilst it
+swims in gradually decreasing circles round a shoal of fishes, which
+are thus kept crowded together, falling an easy prey to their enemy.
+Statements that it has been seen to attack Whales and other large
+Cetaceans, rest upon erroneous observations.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Selache.</span>—The second dorsal and anal very small. A pit
+at the root of the caudal fin, which is provided with a lower
+lobe. Side of the tail with a keel. Gill-openings extremely
+wide. Teeth very small, numerous, conical, without serrature or
+lateral cusps.</p>
+</div>
+
+<p>Also this genus consists of one species only, the “Basking Shark”
+(Pélerin of the French). It is the largest Shark of the North Atlantic,
+growing to a length of more than thirty feet. It is quite harmless if
+not attacked; its food consisting of small fishes, and other small
+marine animals swimming in shoals. On the west coast of Ireland it
+is chased for the sake of the oil which is extracted from the liver,
+one fish yielding from a ton to a ton and a-half. Its capture is not
+unattended with danger, as one blow from the enormously strong tail is
+sufficient to stave in the sides of a large boat. At certain<span class="pagenum" id="Page_323">[323]</span> seasons
+it is gregarious, and many specimens may be seen in calm weather lying
+together motionless, with the upper part of the back raised above the
+surface of the water; a habit from which this Shark has derived its
+name. The buccal and branchial cavities are of extraordinary width,
+and, in consequence of the flabby condition of those parts, the head
+presents a variable and singular appearance in specimens lying dead on
+the ground. This peculiarity, as well as the circumstance that young
+specimens have a much longer and more pointed snout than adult ones,
+has led to the erroneous opinion that several different genera and
+species of Basking Shark occur in the European seas. The branchial
+arches of <i>Selache</i> are provided with a very broad fringe of
+long (five to six inches) and thin gill-rakers, possessing the same
+microscopical structure as the teeth and dermal productions of Sharks.
+Similar gill-rakers have been found in a fossil state in the Crag of
+Anvers in Belgium, proving the existence of this Selachian type in the
+tertiary epoch. Nothing is known of the reproduction of this fish.
+The latest contributions to its history are by <i>Steenstrup</i> in
+“Overs. Dansk. Vidensk. Selsk., Forhandl.” 1873, and by <i>Pavesi</i>
+in “Annal. Mus. Civ. Geneva,” 1874 and 1878.</p>
+
+
+<h6 class="smcap">Third Family—Rhinodontidæ.</h6>
+
+<p><i>No nictitating membrane. Anal fin present. Two dorsal fins, the
+first nearly opposite to the ventrals, without spine in front. Mouth
+and nostril near the extremity of the snout.</i></p>
+
+<p>This small family comprises one species only, <i>Rhinodon typicus</i>,
+a gigantic Shark, which is known to exceed a length of fifty feet,
+but is stated to attain that of seventy. It does not appear to be
+rare in the western parts of the Indian Ocean, and possibly occurs
+also in the Pacific. It is one of the most interesting forms, not
+unlike the Basking Shark of the Northern Seas, having gill-rakers like
+that species;<span class="pagenum" id="Page_324">[324]</span> but very little is known of its structure and mode of
+life. It is perfectly harmless, its teeth being extremely small and
+numerous, placed in broad bands; it has been stated to feed on tang,
+an observation which requires confirmation. The snout is very broad,
+short, and flat; the eyes are very small. A pit at the root of the
+caudal fin which has the lower lobe well developed; side of the tail
+with a keel. A characteristic figure of this fish has been given by A.
+Smith in his “Illustrations of the Zoology of South Africa,” Plate 26,
+from a specimen which came ashore at the Cape of Good Hope.</p>
+
+  <div class="figcenter" id="fig115" style="max-width: 390px">
+     <img
+    class="p1"   
+    src="images/fig115.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 115.—Dentition of Notidanus indicus. <i>a</i>,
+teeth in function; <i>b</i>, teeth in reserve; <i>u</i>, upper, and
+<i>l</i>, lower, tooth, of natural size.</p>
+  </div>
+
+
+<h6 class="smcap">Fourth Family—Notidanidæ.</h6>
+
+<p><i>No nictitating membrane. One dorsal fin only, without spine,
+opposite to the anal.</i></p>
+
+<p><span class="pagenum" id="Page_325">[325]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Notidanus.</span>—Dentition unequal in the jaws: in the upper
+jaw one or two pairs of awl-shaped teeth, the following six
+being broader, and provided with several cusps, one of which is
+much the strongest. Lower jaw with six large comb-like teeth on
+each side, beside the smaller posterior teeth. Spiracles small,
+on the side of the neck. No pit at the root of the caudal fin.
+Gill-openings wide, six in number in <i>Hexanchus</i>, seven in
+<i>Heptanchus</i>.</p>
+</div>
+
+<p>Four species are known, distributed over nearly all the tropical and
+sub-tropical seas; they attain to a length of about fifteen feet.
+Fossil teeth belonging to this type have been found in Jurassic and
+later formations (<i>Notidanus</i> and <i>Aellopos</i>).</p>
+
+
+<h6 class="smcap">Fifth Family—Scylliidæ.</h6>
+
+<p><i>Two dorsal fins, without spine: the first above or behind the
+ventrals; anal fin present. No nictitating membrane. Spiracle always
+distinct. Mouth inferior. Teeth small, several series generally being
+in function.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scyllium.</span>—The origin of the anal fin is always in
+advance of that of the second dorsal. Nasal cavity separate from
+the mouth. Teeth small, with a middle longer cusp, and generally
+one or two small lateral cusps arranged in numerous series. Eggs
+similar to those of the Rays (Fig. <a href="#fig79">79</a>, p. 167).</p>
+</div>
+
+<p>The fishes of this genus are of small size, and commonly called
+“Dog-fishes.” They are coast fishes, living on the bottom, and feeding
+on Crustaceans, dead fishes, etc. None of the eight species known have
+a very wide distribution, but where they occur they are generally
+sufficiently abundant to prove troublesome to fishermen. They inhabit
+most parts of the temperate and tropical seas. On the British coasts
+two species are found, the “Larger” and “Lesser spotted Dog-fish,”
+<i>Scyllium canicula</i> and <i>Scyllium catulus</i>, which are
+said to be more plentiful among the Orkney Islands than elsewhere.
+They are scarcely ever brought to market; but the fishermen of some
+localities do not disdain to eat them. Their flesh is<span class="pagenum" id="Page_326">[326]</span> remarkably
+white, a little fibrous, and dry. In the Orkneys they are skinned,
+split up, cleaned, and then spread out on the rocks to dry for home
+consumption. The skins are used for smoothing down cabinet-work. It
+would be worth while to apply the fins of these and other Sharks, which
+are so extensively used in China for making gelatine soups, to the same
+purpose in this country, or to dry them for exportation to the East.
+Most of the species of Dog-fishes are spotted, and those of the allied
+genera, <i>Parascyllium</i> and <i>Chiloscyllium</i>, very handsomely
+ornamented.</p>
+
+<p>Closely allied to <i>Scyllium</i> is <i>Pristiurus</i>, from the coasts
+of Europe, which is provided with a series of small flat spines on each
+side of the upper edge of the caudal fin.</p>
+
+<p>Fossil forms of Dog-fishes are not scarce in the Lias and Chalk:
+<i>Scylliodus</i>, <i>Palæoscyllium</i>, <i>Thyellina</i>,
+<i>Pristiurus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ginglymostoma.</span>—The second dorsal fin opposite to, and
+somewhat in advance of, the anal. Eyes very small; spiracle
+minute and behind the eye. Nasal and buccal cavities confluent.
+The nasal valves of both sides form one quadrangular flap in
+front of the mouth, each being provided with a free cylindrical
+cirrhus. The fourth and fifth gill-openings are close
+together. The teeth stand either in many series, each having
+a strong median cusp and one or two smaller ones on each side
+(<i>Ginglymostoma</i>), or they stand in a few (three) series
+only, the foremost only being in function, and each tooth having
+a convex, finely and equally serrated margin (<i>Nebrius</i>).</p>
+</div>
+
+<p>Four species from the tropical parts of the Atlantic and Indian Oceans,
+attaining to a length of some 12 feet. Pelagic.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Stegostoma.</span>—The first dorsal above the ventrals,
+the second in advance of the anal, which is very close to the
+caudal. Tail, with the caudal fin, exceedingly long, measuring
+one-half of the total length. Eyes very small, spiracle as wide
+as, and situated behind, the orbit. Nasal and buccal cavities
+confluent. Snout very obtuse; upper lip very thick, like a pad,
+bent downwards<span class="pagenum" id="Page_327">[327]</span> over the mouth, with a free cylindrical cirrhus
+on each side. Teeth small, trilobed, in many series, occupying
+in both jaws a transverse flat subquadrangular patch. The fourth
+and fifth gill-openings are close together.</p>
+</div>
+
+<p>The single species (<i>St. tigrinum</i>) for which this genus has been
+formed, is one of the commonest and handsomest sharks of the Indian
+Ocean. Young individuals keep generally close to the coasts, whilst
+the adult, which are from 10 to 15 feet long, are not rarely met in
+the open ocean. The colour is a brownish yellow, ornamented with black
+or brown transverse bands, or with snuff-coloured rounded spots; hence
+this shark is frequently mentioned by the names of “Zebra-Shark” or
+“Tiger-Shark.”</p>
+
+  <div class="figcenter" id="fig116" style="max-width: 649px">
+     <img
+    class="p1"   
+    src="images/fig116.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 116.—Chiloscyllium trispeculare, from
+North-western Australia.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chiloscyllium.</span>—The first dorsal fin above or behind
+the ventrals. Anal fin placed far behind the second dorsal, and
+very close to the caudal. Spiracle very distinct, below the eye.
+Nasal and buccal cavities confluent. Nasal valve folded, with a
+cirrhus. Teeth small, triangular, with or without lateral cusps.
+The two last gill-openings close together.</p>
+</div>
+
+<p>“Dog-fishes,” from the Indian Ocean, of small size. Four species are
+known, of which one, <i>Ch. indicum</i>, is one of the commonest
+shore-fishes on the coasts of this region, extending from the southern
+extremity of the African Continent to Japan.</p>
+
+  <div class="figcenter" id="fig117" style="max-width: 413px">
+     <img
+    class="p1"   
+    src="images/fig117.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 117.—Confluent nasal and buccal cavities of the
+same fish.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_328">[328]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Crossorhinus.</span>—The first dorsal behind the ventrals,
+the second in advance of the anal, which is very close to the
+caudal. Tail rather short. Eyes small. Spiracle a wide oblique
+slit, behind and below the eye. Nasal and buccal cavities
+confluent. Head broad, flat, with the snout very obtuse; mouth
+wide, nearly anterior. A free nasal cirrhus; sides of the head
+with skinny appendages. Anterior teeth rather large, long and
+slender, without lateral lobes, the lateral tricuspid, smaller,
+forming a few series only. The fourth and fifth gill-openings
+close together.</p>
+</div>
+
+<p>Three species are known from the Australian and Japanese coasts. They
+are evidently ground-sharks, which lie concealed on the bottom watching
+for their prey. In accordance with this habit their colour closely
+assimilates that of a rock or stone covered with short vegetable and
+coralline growth—a resemblance increased by the frond-like tentacles
+on the side of the head. This peculiarity of the integuments, which is
+developed in a yet higher degree in Pediculati and Lophobranchs, is not
+met with in any other Selachian. These Sharks grow to a length of 10
+feet.</p>
+
+
+<h6 class="smcap">Sixth Family—Hybodontidæ.</h6>
+
+<p><i>Two dorsal fins, each with a serrated spine. Teeth rounded,
+longitudinally striated, with one larger, and from two to four smaller
+lateral cusps. Skin covered with shagreen.</i></p>
+
+<p>Extinct. From carboniferous, liassic, and triassic formations. Several
+genera have been distinguished; and if <i>Cladodus</i> belongs to this
+family, it would have been represented even in the Devonian.</p>
+
+  <div class="figcenter" id="fig118" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig118.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 118.—Spine of Hybodus subcarinatus.</p>
+  </div>
+
+
+<h6 class="smcap">Seventh Family—Cestraciontidæ.</h6>
+
+<p><i>No nictitating membrane. Two dorsal fins, the first<span class="pagenum" id="Page_329">[329]</span> opposite to
+the space between pectoral and ventral fins; anal fin present. Nasal
+and buccal cavities confluent. Teeth obtuse, several series being in
+function.</i></p>
+
+  <div class="figcenter" id="fig119" style="max-width: 358px">
+     <img
+    class="p1"   
+    src="images/fig119.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 119.—Jaws of Port Jackson Shark, Cestracion philippi.</p>
+  </div>
+
+  <div class="figcenter" id="fig120" style="max-width: 381px">
+     <img
+    class="p1"   
+    src="images/fig120.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 120.—Upper jaw of the same, half natural size.</p>
+  </div>
+
+<p>This family is one of particular interest, because representatives of
+it occur in numerous modifications in primary and secondary strata.
+Their dentition is uniformly adapted for the prehension and mastication
+of crustaceous and hard-shelled animals. The fossil forms far
+exceeded in size the species of the only surviving genus; they make,
+their appearance with <i>Ctenoptychius</i> in the Devonian; this is
+succeeded in the coal-measures by <i>Psammodus</i>, <i>Chomatodus</i>,
+<i>Petrodus</i>, <i>Coch</i><i>liodus</i>,<span class="pagenum" id="Page_330">[330]</span> <i>Polyrhizodus</i>,
+etc.; in the Trias and Chalk by <i>Strophodus</i>, <i>Acrodus</i>,
+<i>Thectodus</i>, and <i>Ptychodus</i>. Of the 25 genera known, 22 have
+lived in the periods preceding the Oolitic.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cestracion (Heterodontus).</span>—Each dorsal fin armed with
+a spine in front; the second in advance of the anal. Mouth
+rather narrow. Spiracles small, below the posterior part of
+the eye. Gill-openings rather narrow. Dentition similar in
+both jaws, viz. small obtuse teeth in front, which in young
+individuals are pointed and provided with from three to five
+cusps. The lateral teeth are large, padlike, twice as broad as
+long, arranged in oblique series, one series being formed by
+much larger teeth than those in the other series.</p>
+</div>
+
+  <div class="figcenter" id="fig121" style="max-width: 329px">
+     <img
+    class="p1"   
+    src="images/fig121.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 121.—Cochliodus contortus.</p>
+  </div>
+
+  <div class="figcenter" id="fig122" style="max-width: 600px">
+     <img
+    class="p1"   
+    src="images/fig122.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 122.—Cestracion galeatus, Australia.</p>
+  </div>
+
+<p>Four species are known from Japan, Amboyna, Australia, the Galapagoes
+Islands, and California; none exceed a length of 5 feet. The egg has
+been figured on p. 168 (Fig. <a href="#fig80">80</a>).</p>
+
+
+<h6 class="smcap">Eighth Family—Spinacidæ.</h6>
+
+<p><i>No membrana nictitans. Two dorsal fins; no anal. Mouth but slightly
+arched; a long, deep, straight, oblique groove on each side of the
+mouth. Spiracles present; gill-openings narrow. Pectoral fins not
+notched at their origin.</i></p>
+
+<p>The oldest representative of this family (<i>Palæospinax</i>)<span class="pagenum" id="Page_331">[331]</span> occurs
+at Lyme Regis; its skin is granular; each dorsal fin possesses a spine;
+the teeth in the jaws are dissimilar—the upper being multicuspid,
+longitudinally ribbed as in Hybodus, the lower smooth and tricuspid.
+<i>Drepanophorus</i> and <i>Spinax primævus</i> occur in Cretaceous
+formations of England and the Lebanon.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centrina.</span>—Each dorsal fin with a strong spine. Trunk
+rather elevated, trihedral, with a fold of the skin running
+along each side of the belly. Teeth of the lower jaw erect,
+triangular, finely serrated; those of the upper slender,
+conical, forming a group in front of the jaw. Spiracles wide,
+behind the eye.</p>
+</div>
+
+<p>One species, <i>Centrina salviani</i>, from the Mediterranean and
+neighbouring parts of the Atlantic; of small size.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acanthias.</span>—Each dorsal fin with a spine. Teeth equal
+in both jaws, rather small; their point is so much turned aside
+that the inner margin of the tooth forms the cutting edge.
+Spiracles rather wide, immediately behind the eye.</p>
+</div>
+
+<p>The two species of “Spiny Dog-fishes,” <i>A. vulgaris</i> and <i>A.
+blainvillii</i>, have a very remarkable distribution, being found in
+the temperate seas of the Northern and Southern Hemispheres, but not
+in the intermediate tropical zone. They are of small size, but occur
+at times in incredible numbers, 20,000 having been taken in one scene
+on the Cornish coast. They do much injury to the fishermen by cutting
+their lines and carrying off their hooks.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centrophorus.</span>—Each dorsal fin with a spine which,
+however, is sometimes so small as to be hidden below the skin.
+Mouth wide. Teeth of the lower jaw with the point more or less
+inclined backwards and outwards. Upper teeth erect, triangular,
+or narrow, lanceolate, with a single cusp. Spiracles wide,
+behind the eye.</p>
+</div>
+
+<p>Eight species are known from the southern parts of the European seas,
+and one from the Moluccas; they do not appear to exceed a length
+of five feet. According to the<span class="pagenum" id="Page_332">[332]</span> observations of E. P. Wright, some
+of the species at least live at a considerable depth, perhaps at a
+greater depth than any of the other known Sharks. The Portuguese
+fishermen fish for them in 400 or 500 fathoms with a line of some 600
+fathoms in length. The Sharks caught were specimens of <i>Centrophorus
+coelolepis</i>, from three to four feet long. “These sharks, as they
+were hauled into the boat, fell down into it like so many dead pigs;
+there was not the smallest motion of their bodies. There can be no
+reasonable doubt that they were inhabitants of the same great depth as
+<i>Hyalonema</i>” and that, in fact, they were killed by being dragged
+to the surface from the pressure of water under which they lived.
+The dermal productions of some of the species have a very peculiar
+form, being leaf-shaped, pedunculate, or ribbed, or provided with an
+impression.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Spinax.</span>—Each dorsal fin with a spine. Teeth of the
+lower jaw with the point so much turned aside that the inner
+margin of the tooth forms the cutting edge. Upper teeth erect,
+each with a long-pointed cusp and one or two small ones on each
+side. Spiracles wide, superior, behind the eye.</p>
+</div>
+
+<p>Three small species from the Atlantic and the southern extremity of
+America. <i>Centroscyllium</i> is an allied genus from the coast of
+Greenland.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scymnus.</span>—Two short dorsal fins without spine, the
+first at a considerable distance from the ventrals. Dermal
+productions uniformly small. Nostrils at the extremity of the
+snout. Upper teeth small, pointed; lower much larger, dilated,
+erect, triangular, not very numerous. Spiracles wide.</p>
+</div>
+
+<p>A single species, <i>S. lichia</i>, is rather common in the
+Mediterranean and the neighbouring parts of the Atlantic.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Læmargus.</span>—All the fins small; two dorsal fins, without
+spine, the first at a considerable distance from the ventrals.
+Skin uniformly covered with minute tubercles. Nostrils near the
+extremity of the snout. The upper teeth small, narrow,<span class="pagenum" id="Page_333">[333]</span> conical;
+the lower teeth numerous, in several series, the point so much
+turned aside that the inner margin forms a cutting, non-serrated
+edge. Jaws feeble. Spiracles of moderate width.</p>
+</div>
+
+  <div class="figcenter" id="fig123" style="max-width: 436px">
+     <img
+    class="p1"   
+    src="images/fig123.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 123.—Dentition of the Greenland Shark. Some teeth
+are represented of the natural size; those of the lower jaw in three
+series.</p>
+  </div>
+
+<p>The “Greenland Shark” is an inhabitant of the Arctic regions, but
+rarely straying to the latitudes of great Britain; it grows to a length
+of about 15 feet, and, although it never or but rarely attacks man, is
+one of the greatest enemies of the whale, which is often found with
+large pieces bitten out of the tail by this Shark. Its voracity is so
+great that, according to Scoresby, it is absolutely fearless of the
+presence of man whilst engaged in feeding on the carcass of a whale,
+so that it can be pierced through with a spear or knife without being
+driven away. It is stated to be viviparous, and to produce about four
+young at a birth.</p>
+
+  <div class="figcenter" id="fig124" style="max-width: 618px">
+     <img
+    class="p1"   
+    src="images/fig124.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 124.—Læmargus borealis, Greenland Shark.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Echinorhinus.</span>—Two very small dorsal fins, without
+spine,<span class="pagenum" id="Page_334">[334]</span> the first opposite to the ventrals. Skin with scattered
+large round tubercles. Nostrils midway between the mouth and the
+end of the snout. Teeth equal in both jaws, very oblique, the
+point being turned outwards; several strong denticulations on
+each side of the principal point. Spiracles small.</p>
+</div>
+
+<p>The “Spinous Shark” is readily recognised by the short bulky form of
+its body, short tail, and large spinous tubercles. It is evidently a
+ground-shark, which probably lives at some depth and but accidentally
+comes to the surface. More frequently met with in the Mediterranean, it
+has been found several times on the south coast of England, and near
+the Cape of Good Hope.</p>
+
+<p><i>Euprotomicrus</i> and <i>Isistius</i> are two other genera of this
+family; they are pelagic and but little known.</p>
+
+
+<h6 class="smcap">Ninth Family—Rhinidæ.</h6>
+
+<p><i>No anal fin; two dorsal fins. Spiracles present. Pectoral fins
+large, with the basal portion prolonged forwards, but not grown to the
+head.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhina.</span>—Head and body depressed, flat; mouth anterior.
+Gill-openings rather wide, lateral, partly covered by the base
+of the pectoral. Spiracles wide, behind the eyes. Teeth conical,
+pointed, distant. Dorsal fins on the tail.</p>
+</div>
+
+<p>The “Angel-fish,” or “Monk-fish” (<i>Rh. squatina</i>), approaches
+the Rays as regards general form and habits. Within the temperate and
+tropical zones it is almost cosmopolitan, being well known on the
+coasts of Europe, eastern North America, California, Japan, South
+Australia, etc.; it does not seem to exceed a length of five feet; it
+is viviparous, producing about twenty young at a birth.</p>
+
+<p>Extinct forms, closely allied to the “Angel-fish,” are found in the
+Oolite, and have been described as <i>Thaumas</i>. The carboniferous
+genus, <i>Orthacanthus</i>, may have been allied to this family, but it
+was armed with a spine immediately behind the head.</p>
+
+<p><span class="pagenum" id="Page_335">[335]</span></p>
+
+
+<h6 class="smcap">Tenth Family—Pristiophoridæ.</h6>
+
+<p><i>The rostral cartilage is produced, into an exceedingly long, flat
+lamina, armed along each edge with a series of teeth</i> (saw).</p>
+
+<p>These Sharks resemble so much the common Saw-fishes as to be easily
+confounded with them, but their gill-openings are lateral, and not
+inferior. They are also much smaller in size, and a pair of long
+tentacles are inserted at the lower side of the saw. The four species
+known (<i>Pristiophorus</i>) occur in the Australian and Japanese seas.</p>
+
+<p><i>Squaloraja</i>, from the Lias, is supposed to have its nearest
+affinities to this family.</p>
+
+
+<h6>B. <span class="smcap">Batoidei—Rays.</span></h6>
+
+<p>In the typical Rays the body is excessively depressed, and forms,
+with the expanded pectoral fins, a circular or sub-rhomboidal disk,
+of which the slender tail appears as a more or less long appendage.
+In the two families which we shall place first (<i>Pristidæ</i> and
+<i>Rhinobatidæ</i>), the general habit of the body still resembles that
+of the Sharks, but the gill-openings are ventral, as in the true Rays;
+the anal fin is invariably absent, and the dorsal fins, if developed,
+are placed on the tail. The mode of life of those fishes is quite in
+accordance with the form of their body. Whilst the species with a
+shark-like body and muscular tail swim freely through the water, and
+are capable of executing rapid and sustained motions, the true Rays
+lead a sedentary life, moving slowly on the bottom, rarely ascending
+to the surface. Their tail has almost entirely lost the function of an
+organ of locomotion, acting in some merely as a rudder. They progress
+solely by means of the pectoral fins, the broad and thin margins of
+which are set in an undulating motion, entirely identical with that
+of the dorsal and anal fins of the <i>Pleuronectidæ</i>. They are
+exclusively carnivorous, like the Sharks, but unable<span class="pagenum" id="Page_336">[336]</span> to pursue and
+catch rapidly-moving animals; therefore they feed chiefly on molluscous
+and crustaceous animals. However, the colour of their integuments
+assimilates so closely that of their surroundings, that other fishes
+approach them near enough to be captured by them. The mouth of Rays
+being entirely at the lower surface of the head, the prey is not
+directly seized with the jaws; but the fish darts over its victim so as
+to cover and hold it down with its body, when it is conveyed by some
+rapid motions to the mouth.</p>
+
+<p>Rays do not descend to the same depth as Sharks; with one
+exception,<a id="FNanchor_37" href="#Footnote_37" class="fnanchor">[37]</a> at least, none have been known to have been caught by a
+dredge worked in more than 100 fathoms. The majority are coast fishes,
+and have a comparatively limited geographical range, none extending
+from the northern temperate zone into the southern. However, some, if
+not all the species of the family <i>Myliobatidæ</i>, which includes
+the giants of this division of Plagiostomes, have a claim of being
+included among the Pelagic fishes, as they are frequently met with
+in the open ocean at a great distance from the shore. It is probable
+that the occurrence of such individuals in the open sea indicates the
+neighbourhood of some bank or other comparatively shallow locality.
+Many species are exclusively confined to fresh water, and occur far
+inland, especially in tropical America.</p>
+
+<p>The majority are oviparous. All have five pairs of gill-openings. The
+number of known species is about the same as that of Sharks, viz. 140.</p>
+
+
+<h6 class="smcap">First Family—Pristidæ.</h6>
+
+<p><i>The snout is produced into an exceedingly long flat lamina, armed
+with a series of strong teeth along each edge</i> (saw).</p>
+
+<p><span class="pagenum" id="Page_337">[337]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pristis.</span>—Body depressed and elongate, gradually
+passing into the strong and muscular tail. Pectoral fins, with
+the front margins quite free, not extending to the head. No
+tentacles below the saw. Teeth in the jaws minute, obtuse.
+Dorsal fins without spine, the first opposite or close to the
+base of the ventrals.</p>
+</div>
+
+<p>“Saw-fishes.” Abundant in tropical, less so in sub-tropical seas. They
+attain to a considerable size, specimens with a saw 6 feet long and 1
+foot broad at the base not being of uncommon occurrence. The saw, which
+is their weapon of attack, renders them most dangerous to almost all
+the other large inhabitants of the ocean. Its endoskeleton consists
+of three, sometimes five, rarely four, hollow cylindrical tubes,
+placed side by side, tapering towards the end, and incrusted with an
+osseous deposit. These tubes are the rostral processes of the cranial
+cartilage, and exist in all Rays, though in them they are shorter and
+much less developed. The teeth of the saw are implanted in deep sockets
+of the hardened integument. The teeth proper, with which the jaws
+are armed, are much too small for inflicting wounds or seizing other
+animals. Saw-fishes use this weapon in tearing pieces of flesh off
+an animal’s body or ripping open its abdomen. The detached fragments
+or protruding soft parts are then seized by them and swallowed. Five
+distinct species of Saw-fishes are known.</p>
+
+<p>Saws of extinct species have been found in the London clay of Sheppey
+and in the Bagshot sands.</p>
+
+
+<h6 class="smcap">Second Family—Rhinobatidæ.</h6>
+
+<p><i>Tail strong and long, with two well-developed dorsal fins, and a
+longitudinal fold on each side; caudal developed. Disk not excessively
+dilated, the rayed portion of the pectoral fins not being continued to
+the snout.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhynchobatus.</span>—Dorsal fins without spine, the first
+opposite to the ventrals. Caudal fin with the lower lobe well
+developed.<span class="pagenum" id="Page_338">[338]</span> Teeth obtuse, granular, the dental surfaces of the
+jaws being undulated.</p>
+</div>
+
+  <div class="figcenter" id="fig125" style="max-width: 365px">
+     <img
+    class="p1"   
+    src="images/fig125.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 125.—Dentition of <i>Rhynchobatus</i>.</p>
+  </div>
+
+<p>Two species, <i>Rh. ancylostomus</i> and <i>Rh. djeddensis</i>, are
+very common on the tropical coasts of the Indian Ocean. They feed on
+hard-shelled animals, and attain scarcely a length of 8 feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhinobatus.</span>—Cranial cartilage produced into a long
+rostral process, the space between the process and pectoral fin
+being filled by a membrane. Teeth obtuse, with an indistinct
+transverse ridge. Dorsal fins without spine, both at a great
+distance behind the ventral fins. Caudal fin without lower lobe.</p>
+</div>
+
+<p>Numerous on the coasts of tropical and sub-tropical seas; about twelve
+species. <i>Trygonorhina</i> is an allied genus from South Australia.</p>
+
+<p>The oolitic genus <i>Spathobatis</i> is scarcely distinct from
+<i>Rhinobatus</i>; and another fossil from Mount Lebanon has been
+actually referred to this latter genus. <i>Trigorhina</i> from Monte
+Postale must be placed here.</p>
+
+
+<h6 class="smcap">Third Family—Torpedinidæ.</h6>
+
+<p><i>The trunk is a broad, smooth disk. Tail with a longitudinal fold
+on each side; a rayed dorsal fin is generally, and a<span class="pagenum" id="Page_339">[339]</span> caudal always,
+present. Anterior nasal valves confluent into a quadrangular lobe.
+An electric organ composed of vertical hexagonal prisms between the
+pectoral fins and the head.</i></p>
+
+<p>“Electric Rays.” The electric organs with which these fishes are armed
+are large, flat, uniform bodies, lying one on each side of the head,
+bounded behind by the scapular arch, and laterally by the anterior
+crescentic tips of the pectoral fins. They consist of an assemblage
+of vertical hexagonal prisms, whose ends are in contact with the
+integuments above and below; and each prism is subdivided by delicate
+transverse septa, forming cells, filled with a clear, trembling,
+jelly-like fluid, and lined within by an epithelium of nucleated
+corpuscles. Between this epithelium and the transverse septa and walls
+of the prism there is a layer of tissue on which the terminations
+of the nerves and vessels ramify. Hunter counted 470 prisms in each
+battery of <i>Torpedo marmorata</i>, and demonstrated the enormous
+supply of nervous matter which they receive. Each organ receives one
+branch of the Trigeminal nerve and four branches of the Vagus, the
+former, and the three anterior branches of the latter, being each as
+thick as the spinal chord (electric lobes). The fish gives the electric
+shock voluntarily, when it is excited to do so in self-defence or
+intends to stun or to kill its prey; but to receive the shock the
+object must complete the galvanic circuit by communicating with the
+fish at two distinct points, either directly or through the medium
+of some conducting body. If an insulated frog’s leg touches the fish
+by the end of the nerve only, no muscular contractions ensue on the
+discharge of the battery, but a second point of contact immediately
+produces them. It is said that a painful sensation may be produced
+by a discharge conveyed through the medium of a stream of water. The
+electric currents created in these fishes exercise all the other known
+powers of electricity: they render the needle magnetic, decompose
+chemical compounds,<span class="pagenum" id="Page_340">[340]</span> and emit the spark. The dorsal surface of the
+electric organ is positive, the ventral surface negative.</p>
+
+<div class="blockquot">
+
+<p>[The literature on the electric organ of Torpedo is very
+extensive. Here may be mentioned <i>Lorenzini</i>, “Osservazioni
+intorno alle Torpedini,” (1678); <i>Walsh</i>, “On the
+Electric Property of the Torpedo,” in Philos. Trans., 1773;
+<i>Hunter</i>, “Anatomical Observations on the Torpedo,”
+<i>ibid.</i>; <i>Davy</i>, “Observations on the Torpedo,” in
+Philos. Trans., 1834; <i>Matteucci</i> and <i>Savi</i>, “Traité
+des Phénomènes Electro-Physiologiques,” 1844.]</p>
+</div>
+
+<p>Of the genus <i>Torpedo</i> six species are known, distributed over
+the Atlantic and Indian Oceans; three of them are rather common in
+the Mediterranean, and one (<i>T. hebetans</i>) reaches the south
+coast of England. They attain to a width of from two to three feet,
+and specimens of that size are able to disable by a single discharge
+a full-grown man, and, therefore, may prove dangerous to bathing
+persons. Other genera, differing from <i>Torpedo</i> in the position
+and structure of some of the fins, are found in other tropical and
+sub-tropical seas, viz. <i>Narcine</i>, <i>Hypnos</i>, <i>Discopyge</i>
+(Peru), <i>Astrape</i>, and <i>Temera</i>. All, like electric fishes
+generally, have a naked body.</p>
+
+<p>A large fish, of the general appearance of a Torpedo, has been found at
+Monte Bolca; and <i>Cyclobatis</i>, from the upper cretaceous limestone
+of Lebanon, is probably another extinct representative of this family.</p>
+
+
+<h6 class="smcap">Fourth Family—Rajidæ.</h6>
+
+<p><i>Disk broad, rhombic, generally with asperities or spines; tail with
+a longitudinal fold on each side. The pectoral fins extend to the
+snout. No electric organ; no serrated caudal spine.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Raja.</span>—Two dorsal fins on the tail, without spine; tail
+with a rudimentary caudal fin, or without caudal. Each ventral
+fin divided into two by a deep notch. Teeth small, obtuse, or
+pointed. Pectoral fins not extending forwards to the extremity
+of the snout. Nasal valves separated in the middle, where they
+are without a free margin (see Fig. <a href="#fig1">1</a>, p. 34).</p>
+</div>
+
+<p><span class="pagenum" id="Page_341">[341]</span></p>
+
+  <div class="figcenter" id="fig126" style="max-width: 640px">
+     <img
+    class="p1"   
+    src="images/fig126.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 126.—Raja lemprieri, from Tasmania.</p>
+  </div>
+
+  <div class="figcenter" id="fig127" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig127.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 127.—Dermal spines of a male Thornback, Raja
+clavata.</p>
+  </div>
+
+<p>Of all the genera of <i>Batoidei</i>, Rays have the widest geographical
+range; they are chiefly inhabitants of temperate seas, and much more
+numerous in those of the Northern than of the Southern Hemisphere.
+They advance more closely to the Arctic and Antarctic circles than
+any other member of this group. More than thirty species are known,
+of which the following are found on the British coast:—The Thornback
+(<i>R. clavata</i>), the Homelyn Ray (<i>R. maculata</i>), the Starry
+Ray (<i>R. radiata</i>), the Sandy Ray (<i>R. circularis</i>), the
+common Skate (<i>R. batis</i>), the Burton Skate (<i>R. marginata</i>),
+and the Shagreen Skate (<i>R. fullonica</i>). Some of these species,
+especially the Skates, attain a considerable size, the disk measuring
+six and even seven feet across. All are eatable, and some of them
+regularly brought to market. In the majority of the species peculiar
+sexual differences have been observed. In some, as in the Thornback,
+all or some of the teeth are pointed in the male sex, whilst they are
+obtuse and flat in the female. The males of all are armed with patches
+of claw-like spines, retractile in grooves of the integument, and
+serially arranged occupying a space on the upper side of the pectoral
+fin<span class="pagenum" id="Page_342">[342]</span> near the angle of the disk, and frequently also the sides of the
+head. In species which are armed with bucklers or asperities it is the
+female which is principally provided with these dermal productions, the
+male being entirely or nearly smooth. Also the colour is frequently
+different in the two sexes.</p>
+
+<p>Other genera of this family are <i>Psammobatis</i>, <i>Sympterygia</i>,
+and <i>Platyrhina</i>. Although probably this family was well
+represented in cretaceous and tertiary formations, the remains found
+hitherto are comparatively few. <i>Arthropterus</i>, from the Lias,
+seems to have been a true Ray; and dermal spines of a species allied to
+the Thornback (<i>Raja antiqua</i>) are abundant in the crag deposits
+of Suffolk and Norfolk.</p>
+
+
+<h6 class="smcap">Fifth Family—Trygonidæ.</h6>
+
+<p><i>The pectoral fins are uninterruptedly continued to, and confluent
+at, the extremity of the snout. Tail long and slender, without lateral
+longitudinal folds; vertical fins none, or imperfectly developed, often
+replaced by a strong serrated spine.</i></p>
+
+<p>The “Sting-Rays” are as numerous as the Rays proper, but they inhabit
+rather tropical than temperate seas. The species armed with a spine
+use it as a weapon of defence, and the wounds inflicted by it are, to
+man, extremely painful, and have frequently occasioned the loss of a
+limb. We have mentioned above (p. <a href="#Page_190">190</a>) that the danger arises from the
+lacerated nature of the wound as well as from the poisonous property of
+the mucus inoculated. The spines (Fig. <a href="#fig98">98</a>, p. 190) are always barbed on
+the sides, and may be eight or nine inches long in the larger species.
+They are shed from time to time, and replaced by others growing behind
+the one in function, as the teeth of the fishes of this order, or as
+the fangs of a poisonous snake. Fossil species of <i>Trygon</i> and
+<i>Urolophus</i> occur in the tertiary strata of Monte Bolca and Monte
+Postale. The genera into which the various species have been divided
+are the following:—</p>
+
+<p><span class="pagenum" id="Page_343">[343]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Urogymnus.</span>—Tail long, without fin or spine, sometimes
+with a narrow cutaneous fold below. Body densely covered with
+osseous tubercles. Teeth flattened.</p>
+</div>
+
+<p>Only one species is known (<i>U. asperrimus</i>), common in the Indian
+Ocean, and with a body from 4 to 5 feet long; the skin is frequently
+used for covering shields and the handles of swords and other weapons,
+its rough surface offering a firm hold to the hand.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Trygon.</span>—Tail very long, tapering, armed with a long
+arrow-shaped barbed spine. Body smooth or with tubercles. Nasal
+valves coalescent into a quadrangular flap. Teeth flattened.</p>
+</div>
+
+<p>Some twenty-five species are known, one of which (<i>T. pastinaca</i>)
+extends from the south coast of England and the east coast of North
+America through the Atlantic and Indian Ocean to Japan. The majority
+of the species belong to the tropical parts of the Indian and Atlantic
+Oceans; some inhabit exclusively freshwaters of eastern tropical
+America. A closely allied genus is <i>Tæniura</i>, with six species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Urolophus.</span>—Tail of moderate length, with a distinct
+rayed terminal fin, armed with a barbed spine, without or with a
+rudimentary dorsal fin. Teeth flattened.</p>
+</div>
+
+<p>Seven species from tropical seas, apparently of small size.</p>
+
+  <div class="figcenter" id="fig128" style="max-width: 600px">
+     <img
+    class="p1"   
+    src="images/fig128.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 128.—Urolophus cruciatus, from Australia.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_344">[344]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pteroplatea.</span>—Body at least twice as broad as long;
+tail very short and thin, without or with a rudimentary fin, and
+with a serrated spine. Teeth very small, uni- or tri-cuspid.</p>
+</div>
+
+<p>Six species from temperate and tropical seas.</p>
+
+
+<h6 class="smcap">Sixth Family—Myliobatidæ.</h6>
+
+<p><i>The disk is very broad, in consequence of the great development of
+the pectoral fins, which, however, leave the sides of the head free,
+and reappear at the extremity of the snout as a pair of detached
+(cephalic) fins. Viviparous.</i></p>
+
+<p>“Devil-fishes,” “Sea-devils,” or “Eagle-rays.” Generally of large
+size, inhabiting temperate and tropical seas. Some genera possess a
+pair of singular cephalic processes, which generally project in a
+direction parallel to the longitudinal axis of the body, but are said
+to be flexible in the living fish, and used for scooping food from the
+bottom and conveying it to the mouth. In all the species the dentition
+consists of perfectly flat molars, forming a kind of mosaic pavement in
+both the upper and lower jaws: a most perfect mechanical arrangement
+for crushing alimentary substances.</p>
+
+  <div class="figcenter" id="fig129" style="max-width: 443px">
+     <img
+    class="p1"   
+    src="images/fig129.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 129.—Jaws of an Eagle-Ray, <i>Myliobatis
+aquila.</i></p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Myliobatis.</span>—Teeth sexangular, large, flat,
+tessellated, those in the middle much broader than long; several
+narrower series on<span class="pagenum" id="Page_345">[345]</span> each side. Tail very long and thin, with a
+dorsal fin near its root; generally a serrated spine behind the
+fin.</p>
+</div>
+
+<p>Seven species are known, two of which are European, one (<i>M.
+aquila</i>) being almost cosmopolitan, and occasionally found on the
+British coast. The young differ much from the adult, having no median
+series of larger teeth, but all the teeth of equal size and regularly
+sexangular. Also the tail is much longer in young examples than in old
+ones, and the coloration more ornamental. Teeth of species very closely
+allied to, or perhaps even identical with, existing species, are found
+in tertiary formations.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aëtobatis.</span>—Form of the head, body, and tail as
+<i>Myliobatis</i>. The nasal valves remain separate, each
+forming a long flap. The lower dental lamina projects beyond the
+upper. Teeth flat, broad, forming a single series, equivalent
+to the median series of <i>Myliobatis</i>, there being no small
+lateral teeth.</p>
+</div>
+
+  <div class="figcenter" id="fig130" style="max-width: 399px">
+     <img
+    class="p1"   
+    src="images/fig130.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 130.—Aëtobatis narinari.</p>
+  </div>
+
+<p>One species only (<i>A. narinari</i>) which is found in almost<span class="pagenum" id="Page_346">[346]</span> all
+tropical seas, and of exceedingly common occurrence in the Atlantic and
+Indian Oceans; it does not seem to grow to a very large size (perhaps
+not exceeding 5 feet in width), and is readily recognised by numerous
+round bluish-white spots, with which the back is ornamented. Fossils of
+this genus occur in the English Eocenes and the Swiss Molasse.</p>
+
+  <div class="figcenter" id="fig131" style="max-width: 255px">
+     <img
+    class="p1"   
+    src="images/fig131.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 131.—Aëtobatis subarcuatus, from Bracklesham.</p>
+  </div>
+
+<p><span class="smcap">Rhinoptera</span>.—The cephalic appendages are bent inwards, and
+situated at the lower side of the snout. Nasal valves confluent into
+a broad flap, with free margin. Teeth broad, flat, tessellated, in
+five or more series, the middle being the broadest, and the others
+decreasing in width outwards. Tail very slender, with a dorsal fin
+before the serrated spine.</p>
+
+  <div class="figcenter" id="fig132" style="max-width: 329px">
+     <img
+    class="p1"   
+    src="images/fig132.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 132.—Rhinoptera woodwardi; fossil.</p>
+  </div>
+
+  <div class="figcenter" id="fig133" style="max-width: 263px">
+     <img
+    class="p1"   
+    src="images/fig133.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 133.—Rhinoptera polyodon.</p>
+  </div>
+
+<p>Seven species from tropical and sub-tropical seas are known; of
+<i>Rhinoptera polyodon</i> nothing is known except the jaws; and as its
+dentition is very peculiar, no opportunity should be lost of obtaining
+and preserving entire animals. Teeth very similar to those of existing
+species, and described as <i>Zygobatis</i>, occur<span class="pagenum" id="Page_347">[347]</span> in the Norwich Crag
+and in Miocene formations of Switzerland.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Dicerobatis (Cephaloptera).</span>—Cephalic appendages
+pointing straight forwards or inwards. Nostrils widely separated
+from each other. Mouth inferior, wide. Both jaws with very
+numerous and very small flat or tubercular teeth. Tail very
+slender, with a dorsal fin between the ventrals, and with or
+without a serrated spine.</p>
+
+<p><span class="smcap">Ceratoptera.</span>—Cephalic appendages pointing forwards or
+inwards. Mouth anterior; wide. Teeth in the lower jaw only, very
+small. Tail very slender, with a dorsal fin between the ventrals
+and without spine.</p>
+</div>
+
+  <div class="figcenter" id="fig134" style="max-width: 515px">
+     <img
+    class="p1"   
+    src="images/fig134.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 134.—Dicerobatis draco, from Misol.</p>
+  </div>
+
+<p>The species of these two last genera are not yet well distinguished;
+about five of <i>Dicerobatis</i> and two of <i>Ceratoptera</i> are
+known from tropical and temperate seas, but their occurrence in the
+latter is rather sporadic. Some of them, if not all, attain an enormous
+size. One mentioned by Risso, taken off Messina, weighed 1250 pounds.
+Several observers speak of having seen them in pairs, the male being
+usually the smaller. Of a pair mentioned by Risso the female was first
+taken, and the male remained hovering about the boat for<span class="pagenum" id="Page_348">[348]</span> three days,
+and was afterwards found floating dead on the surface. Still larger
+individuals, but of uncertain species, are mentioned by Lacépède, who
+says that one taken at Barbadoes required seven yoke of oxen to draw
+it. A sketch of another, which was said to be twenty feet long, was
+sent to Lacépède; and Sonnini speaks of one which appeared to him to be
+longer and wider than the ship in which he was sailing. A fœtus taken
+from the uterus of the mother captured at Jamaica, and preserved in
+the British Museum, is five feet broad, and weighed twenty pounds. The
+mother measured fifteen feet in width as well as in length, and was
+between three and four feet thick. The capture of “Devil-fishes” of
+such large size is attended with danger, as they not rarely attack and
+capsize the boat. They are said to be especially dangerous when they
+accompany their young, of which they bring forth one only at a time.</p>
+
+
+<h5 class="smaller">SECOND SUB-ORDER—HOLOCEPHALA.</h5>
+
+<p><i>One external gill-opening only, covered by a fold of the skin, which
+encloses a rudimentary cartilaginous gill-cover; four branchial clefts
+within the gill-cavity. The maxillary and palatal apparatus coalescent
+with the skull.</i></p>
+
+<p>This suborder is represented in the living fauna by one family only,
+<i>Chimæridæ</i>; it forms a passage to the following order of fishes,
+the Ganoids. In external appearance, and with regard to the structure
+of their organs of propagation, the Chimæras are Sharks (See Fig. <a href="#fig96">96</a>,
+p. 184). The males are provided with “claspers” in connection with
+the ventral fins, and the ova are large, encased in a horny capsule,
+and few in number; and there is no doubt that they are impregnated
+within the oviduct, as in Sharks. Chimæras are naked, but, as in
+<i>Scylliidæ</i>, very young individuals possess a series of<span class="pagenum" id="Page_349">[349]</span> small
+“placoid” spines, which occupy the median line of the back, and remind
+us of similar dermal productions in the Rays. The males, besides, are
+provided with a singular erectile appendage, spiny at its extremity,
+and received in a groove on the top of the head. On the other hand, the
+relations of the Chimæras to the Ganoid, and, more especially, Dipnoous
+type become manifest in their notochordal skeleton and continuity
+of cranial cartilage. The spine in front of the first dorsal fin is
+articulated to the neural apophysis, and not merely implanted in the
+soft parts, and immovable as in Sharks. A cartilaginous operculum
+makes its appearance, and the external gill-opening is single. The
+dentition is that of a Dipnoid, each “jaw” being armed with a pair of
+broad dental plates, with the addition of a pair of smaller cutting
+teeth in the upper “jaw.” Fossils of similar dental combination are
+not rare in strata, commencing from the Lias and the bottom of the
+Oolitic series; but it is impossible to decide in every case whether
+the fossil should be referred to the Holocephalous or Dipnoous type.
+According to Newberry, Chimæroid fishes commence in the Devonian with
+<i>Rhynchodus</i>, the remains of which were discovered by him in
+Devonian rocks of Ohio. Undoubted Chimæroids are <i>Elasmodus</i>,
+<i>Psaliodus</i>, <i>Ganodus</i>, <i>Ischyodus</i>, <i>Edaphodon</i>,
+and <i>Elasmognathus</i>, principally from mesozoic and tertiary
+formations. Very similar fossils occur in the corresponding strata
+of North America. A single species of <i>Callorhynchus</i> has been
+discovered by H. Hector in the Lower Greensand of New Zealand.</p>
+
+<p>The living Chimæras are few in number, and remain within very moderate
+dimensions, probably not exceeding a length of five feet, inclusive
+of their long filamentous, diphycercal tail. They are referred to two
+genera.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chimæra.</span>—Snout soft, prominent, without appendage. The
+dorsal fins occupying the greater part of the back, anterior
+with a very strong and long spine. Longitudinal axis of the
+tail nearly<span class="pagenum" id="Page_350">[350]</span> the same as that of the trunk, its extremity being
+provided with a low fin above and below, similar in form to a
+dorsal and anal fin. Anal fin very low.</p>
+</div>
+
+<p>Three species are known: <i>Ch. monstrosa</i>, from the coasts of
+Europe and Japan and the Cape of Good Hope; <i>Ch. colliei</i> from the
+west coast of North America; and <i>Ch. affinis</i> from the coast of
+Portugal. (See Fig. <a href="#fig96">96</a>, p. 184.)</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Callorhynchus.</span>—Snout with a cartilaginous prominence,
+terminating in a cutaneous flap. Two dorsal fins, the anterior
+with a very strong and long spine. Extremity of the tail
+distinctly turned upwards, with a fin along its lower edge, but
+without one above. Anal fin close to the caudal, short and deep.</p>
+</div>
+
+<p>One species (<i>C. antarcticus</i>) is common in the Southern temperate
+zone. Cunningham describes the egg (see Fig. <a href="#fig81">81</a>, p. 169), as being of
+a dark greenish-black colour, and, in general, measuring from eight
+to nine or even ten inches in length, by about three in breadth. It
+consists of a central, somewhat spindle-shaped convex area (between
+the horny walls of which the young fish lies), surrounded by a broad
+plicated margin, which is fringed at the edge, and covered on the under
+surface with fine light brownish-yellow hairs.</p>
+
+
+<h4 class="smaller">SECOND ORDER—GANOIDEI.</h4>
+
+<p><i>Skeleton cartilaginous or ossified. Body with medial and paired
+fins, the hinder pair abdominal. Gills free, rarely partially attached
+to the walls of the gill-cavity. One external gill-opening only on
+each side; a gill-cover. Air-bladder with a pneumatic duct. Ova small,
+impregnated after exclusion. Embryo sometimes with external gills.</i></p>
+
+<p>To this order belong the majority of the fossil fish remains of
+palæozoic and mesozoic age, whilst it is very scantily represented
+in the recent fauna, and evidently verging towards total extinction.
+The knowledge of the fossil forms, based on mere fragments of the
+hard parts of the body only,<span class="pagenum" id="Page_351">[351]</span> is very incomplete, and therefore their
+classification is in a most unsatisfactory state. In the following
+pages only the most important groups will be mentioned.</p>
+
+<div class="blockquot">
+
+<p>[For a study of details we have to refer to <i>Agassiz</i>,
+“Poissons Fossiles;” <i>Owen</i>, “Palæontology,” Edinb. 1861,
+8vo; <i>Huxley</i>, “Preliminary Essay upon the Systematic
+Arrangement of the Fishes of the Devonian Epoch,” in Mem.
+Geolog. Survey, Dec. 10; Lond. 1861, and “Illustrations of the
+Structure of Crossopterygian Ganoids,” <i>ibid.</i> December 12,
+1866; <i>Traquair</i>, “The Ganoids of the British Carboniferous
+Formations,” part I. “Palæoniscidæ.” Palæontogr. Soc. Lond.
+1877.]</p>
+</div>
+
+<p>Eight suborders may be distinguished at present.</p>
+
+
+<h5 class="smaller">FIRST SUB-ORDER—PLACODERMI.</h5>
+
+<p><i>Extinct. The head and pectoral region of the body encased in great
+bony, sculptured plates, with dots of enamel; the remainder of the body
+naked, or with ganoid scales; skeleton notochordal.</i></p>
+
+<p>Comprises the oldest vertebrate remains, from Devonian and
+Carboniferous formations. <i>Pterichthys</i>: (Figs. <a href="#fig135">135</a> and <a href="#fig136">136</a>),
+tail tapering, covered with small ganoid scales, without caudal fin;
+the cephalic shield was probably moveably joined to the cuirass of the
+trunk, and both were composed of several pieces; the abdominal shield
+consisted of one single median plate, and two pairs of lateral plates,
+a third small pair being sometimes observed detached in front of the
+anterior pair; pectoral exceedingly long, consisting of two pieces
+movably connected with each other; tail scaly, and short; a small
+dorsal fin placed on the tail; a pair of small ventrals; jaws small,
+with confluent denticles. Several species have been distinguished
+in remains found in the strata of Caithness and other localities in
+Scotland. <i>Coccosteus</i> (Fig. <a href="#fig137">137</a>, p. 354): all the bony plates are
+firmly united, no pectoral spines; tail naked and long; a dorsal and
+anal fin supported by interneural and interhæmal spines. Dentition<span class="pagenum" id="Page_352">[352]</span>
+unknown. <i>Dinichthys</i>: a gigantic fish from the Devonian of North
+America (estimated at from 15 to 18 feet in length), with the dermal
+covering very similar to that of Coccosteus,<span class="pagenum" id="Page_353">[353]</span> but with a simple arched
+dorsal shield. As in this latter genus the caudal extremity does not
+possess external or internal bony parts, and the ventral plastron
+of both genera corresponds in every particular; the dentition is so
+singularly like that of Lepidosiren, that Newberry (Geolog. Survey of
+Ohio, vol. ii. part 2) considers this genus to be in genetic relation
+to the Dipnoi. The following genera have been united in a separate
+family, <i>Cephalaspidæ</i>; viz. <i>Cephal</i><i>aspis</i>:<span class="pagenum" id="Page_354">[354]</span> head
+covered by a continuous shield with tubercular surface, produced into
+a horn at each posterior corner; a median dorsal backward prolongation
+bears a spine; heterocercal. <i>Auchenaspis</i> and <i>Didymaspis</i>:
+allied to the preceding, but with the cephalic shield divided into a
+larger anterior and smaller posterior piece. <i>Pteraspis</i>: with
+the cephalic shield finely striated or grooved, composed of seven
+pieces. <i>Scaphaspis</i> and <i>Cyathaspis</i>: with the surface
+of the head-shield similarly sculptured as in <i>Pteraspis</i>, but
+simple in the former, and composed of four pieces in the latter.
+<i>Astrolepis</i>: attained to the gigantic size of between twenty and
+thirty feet; its mouth was furnished with two rows of teeth, of which
+the outer ones were small, the inner much larger.</p>
+
+  <div class="figcenter" id="fig135" style="max-width: 299px">
+     <img
+    class="p1"   
+    src="images/fig135.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 135.—Dorsal surface of Pterichthys, after Pander.
+<i>d</i>, Dorsal fin; <i>c</i>, pectoral member; 2–10, head-bucklers;
+11–13, dorsal bucklers.</p>
+  </div>
+
+  <div class="figcenter" id="fig136" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig136.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 136.—Ventral aspect of Pterichthys, after Pander.
+15, mandible (?); 16–21, ventral bucklers.</p>
+  </div>
+
+  <div class="figcenter" id="fig137" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig137.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 137.—Coccosteus, after Pander. <i>A</i>, Anal fin;
+<i>D</i>, Dorsal fin; <i>C</i>, Heterocercal tail; <i>c</i>, notochord;
+<i>n</i>, neurals; <i>h</i>, hæmals; 6–24, bucklers.</p>
+  </div>
+
+<div class="blockquot">
+
+<p>[See Ray Lankester, A. Monograph of the Fishes of the Old Red
+Sandstone of Britain. Part I. Cephalaspidæ. Lond. 1868 and 1870.
+4to.]</p>
+</div>
+
+<p><span class="pagenum" id="Page_355">[355]</span></p>
+
+
+<h5 class="smaller">SECOND SUB-ORDER—ACANTHODINI.</h5>
+
+<p>Extinct. <i>Body oblong, compressed, covered with shagreen; skull
+not ossified; caudal heterocercal. Large spines, similar to those of
+Chondropterygians, in front of some of the median and paired fins.
+The spines are imbedded between the muscles, and not provided with a
+proximal joint.</i></p>
+
+<p><i>Acanthodes</i>, <i>Chiracanthus</i>, from Devonian and Carboniferous
+formations.</p>
+
+
+<h5 class="smaller">THIRD SUB-ORDER—DIPNOI.</h5>
+
+<p><i>Nostrils two pairs, more or less within the mouth; limbs with
+an axial skeleton. Lungs and gills. Skeleton notochordal. No
+branchiostegals.</i><a id="FNanchor_38" href="#Footnote_38" class="fnanchor">[38]</a></p>
+
+
+<h6 class="smcap">First Family—Sirenidæ.</h6>
+
+<p><i>Caudal fin diphycercal; no gular plates; scales cycloid. A pair of
+molars, above and below, and one pair of vomerine teeth.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lepidosiren.</span>—Body eel-shaped, with one continuous
+vertical fin. Limbs reduced to cylindrical filaments, without
+fringe. Vomerine teeth conical, pointed. Each dental lamina
+or molar with strong cusps, supported by vertical ridges. No
+external branchial appendages; five branchial arches, with four
+intervening clefts. Conus arteriosus with two longitudinal
+valves. Ovaries closed sacs.</p>
+</div>
+
+<p>One species only is known from the system of the River Amazons (<i>L.
+paradoxa</i>). It must be very locally distributed, as but a few
+specimens have been brought to Europe, and all recent endeavours to
+obtain others have been unsuccessful. Natterer, by whom this most
+interesting fish was discovered, states that he obtained two specimens,
+one on the Madeira River, near Borba; the other in a backwater of the
+Amazons, above Villa Nova. The natives of the former place called it
+Carámurú, and considered it very scarce. The larger individual<span class="pagenum" id="Page_356">[356]</span> was
+nearly four feet long. It is said to produce a sound not unlike that
+of a cat, and to feed on the roots of mandioca and other vegetables.
+But, to judge from the dentition, this fish is much more likely to be
+carnivorous, like the following. It is one of the greatest desiderata
+of Natural History Collections.</p>
+
+<div class="blockquot">
+
+<p>[Natterer, “Annalen des Wiener Museum’s,” 1839, ii.; Bischoff.
+“Annales des Sciences Naturelles,” 1840. xiv.]</p>
+</div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Protopterus.</span>—Very similar in the general form of
+the body and dentition to <i>Lepidosiren</i>. Pectoral and
+ventral filaments with a fringe containing rays. Three small
+branchial appendages above the small gill-opening; six branchial
+arches, with five intervening clefts. Conus arteriosus with two
+longitudinal valves. Ovaries closed sacs.</p>
+</div>
+
+<p><i>Protopterus annectens</i> is the “Lepidosiren” which is commonly
+found in Zoological collections. It is usually imported from the west
+coast of Africa, where it abounds in many localities; but it is spread
+over the whole of tropical Africa, and forms in many districts of the
+central parts a regular article of food.</p>
+
+  <div class="figcenter" id="fig138" style="max-width: 581px">
+     <img
+    class="p1"   
+    src="images/fig138.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 138.—Protopterus annectens. <i>g</i>, Branchial
+filaments; <i>v</i>, vent.</p>
+  </div>
+
+<p>During the dry season, specimens living in shallow waters which
+periodically dry up, form a cavity in the mud, the inside of which they
+line with a protecting capsule of mucus, and from which they emerge
+again when the rains refill the pools inhabited by them. Whilst they
+remain in this torpid state of existence, the clay-balls containing
+them are frequently dug out, and if the capsules are not broken, the
+fishes imbedded in them can be transported to Europe,<span class="pagenum" id="Page_357">[357]</span> and released
+by being immersed in slightly tepid water. <i>Protopterus</i> is
+exclusively carnivorous, feeding on water-insects, frogs, and fishes,
+and attains a length of six feet.</p>
+
+<p>
+[Owen, “Trans. Linn. Soc.” 1841, xviii.]
+</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ceratodus.</span>—Body elongate, compressed, with one
+continuous vertical fin. Limbs paddle-shaped, with broad, rayed
+fringe. Vomerine teeth incisor-like; molars with flat, undulated
+surface, and lateral prongs. No external branchial appendages.
+Conus arteriosus with transverse series of valves. Ovaries
+transversely lamellated.<a id="FNanchor_39" href="#Footnote_39" class="fnanchor">[39]</a></p>
+</div>
+
+  <div class="figcenter" id="fig139" style="max-width: 553px">
+     <img
+    class="p1"   
+    src="images/fig139.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 139.—<i>Ceratodus miolepis.</i></p>
+  </div>
+
+<p>Two species, <i>C. forsteri</i> and <i>C. miolepis</i>, are known
+from fresh waters of Queensland. The specimens hitherto obtained have
+come from the Burnett, Dawson, and Mary rivers, some from the fresh
+waters of the upper parts, others from the lower brackish portions. The
+fish is said to attain to a weight of twenty pounds and to a length
+of 6 feet. Locally, the settlers call it “Flat-head,” “Burnett- or
+Dawson-Salmon,” and the aborigines “Barramunda,” a name which they
+appear to apply also to other large-scaled freshwater fishes, as the
+Osteoglossum leichardti. In the stomach there is generally found an
+enormous quantity of the leaves of plants growing on the banks of
+rivers, evidently eaten after they had fallen into the water and when
+in a decomposing condition. The flesh of the fish is salmon-coloured,
+and much esteemed as food.</p>
+
+<p>The Barramunda is said to be in the habit of going on land, or at least
+on mud-flats; and this assertion appears to<span class="pagenum" id="Page_358">[358]</span> be borne out by the fact
+that it is provided with a lung. However, it is much more probable
+that it rises now and then to the surface of the water in order to
+fill its lung with air, and then descends again until the air is so
+much deoxygenised as to render a renewal of it necessary. It is also
+said to make a grunting noise, which may be heard at night for some
+distance. This noise is probably produced by the passage of the air
+through the œsophagus when it is expelled for the purpose of renewal.
+As the Barramunda has perfectly developed gills, beside the lung, we
+can hardly doubt that, when it is in water of normal composition,
+and sufficiently pure to yield the necessary supply of oxygen, these
+organs are sufficient for the purpose of breathing, and that the
+respiratory function rests with them alone. But when the fish is
+compelled to sojourn in thick muddy water charged with gases, which are
+the products of decomposing organic matter (and this must be the case
+very frequently during the droughts which annually exhaust the creeks
+of tropical Australia), it commences to breathe air with its lung in
+the way indicated above. If the medium in which it happens to be is
+perfectly unfit for breathing the gills cease to have any function;
+if only in a less degree the gills may still continue to assist in
+respiration. The Barramunda, in fact, can breathe by either gills or
+lungs alone, or by both simultaneously. It is not probable that it
+lives freely out of the water, its limbs being much too flexible for
+supporting the heavy and unwieldy body, and too feeble generally to be
+of much use in locomotion on land. However, it is quite possible that
+it is occasionally compelled to leave the water, although we cannot
+believe that it can exist without it in a lively condition for any
+length of time.</p>
+
+<p>Of its propagation or development we know nothing, except that it
+deposits a great number of eggs of the size of those of a newt, and
+enveloped in a gelatinous case. We<span class="pagenum" id="Page_359">[359]</span> may infer that the young are
+provided with external gills, as in Protopterus and Polypterus.</p>
+
+  <div class="figcenter" id="fig140" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig140.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 140.—Tooth of fossil <i>Ceratodus</i> from Aust.,
+near Bristol, natural size.</p>
+  </div>
+
+<p>The discovery of <i>Ceratodus</i> does not date farther back than
+the year 1870, and proved to be of the greatest interest, not only
+on account of the relation of this creature to the other living
+<i>Dipnoi</i> and <i>Ganoidei</i>, but also because it threw fresh
+light on those singular fossil teeth which are found in strata of
+Triassic and Jurassic formations in various parts of Europe, India, and
+America. These teeth, of which there is a great variety with regard to
+general shape and size, are sometimes two inches long, much longer than
+broad, depressed, with a flat or slightly undulated, always punctated
+crown, with one margin convex, and with from three to seven prongs
+projecting on the opposite margin.</p>
+
+  <div class="figcenter" id="fig141" style="max-width: 509px">
+     <img
+    class="p1"   
+    src="images/fig141.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 141.—Dipterus macrolepidotus.</p>
+  </div>
+
+
+<h6 class="smcap">Second Family—Ctenododipteridæ.</h6>
+
+<p><i>Caudal fin heterocercal. Gular plates. Scales cycloid. Two pairs of
+molars and one pair of vomerine teeth.</i></p>
+
+<p>Extinct. <i>Dipterus</i> (<i>Ctenodus</i>), <i>Heliodus</i> from
+Devonian strata.</p>
+
+<p><span class="pagenum" id="Page_360">[360]</span></p>
+
+
+<p class="smcap center">Third Family—Phaneropleuridæ.</p>
+
+<p><i>Caudal fin diphycercal; vertical fin continuous. Gular plates.
+Scales cycloid. Jaws with a series of minute conical teeth on the
+margin.</i></p>
+
+<p>Extinct. <i>Phaneropleuron</i> from Devonian formations, and the
+carboniferous <i>Uronemus</i> are probably generically identical.</p>
+
+
+<h5 class="smaller">FOURTH SUB-ORDER—CHONDROSTEI.</h5>
+
+<p><i>Skeleton notochordal; skull cartilaginous, with dermal
+ossifications; branchiostegals few in number or absent. Teeth minute or
+absent. Integuments naked or with bucklers. Caudal fin heterocercal,
+with fulcra. Nostrils double, in front of the eyes.</i></p>
+
+
+<h6 class="smcap">First Family—Acipenseridæ.</h6>
+
+<p><i>Body elongate, sub-cylindrical, with five rows of osseous bucklers.
+Snout produced, subspatulate or conical, with the mouth at its lower
+surface, small, transverse, protractile, toothless. Four barbels in a
+transverse series on the lower side of the snout. Vertical fins with
+a single series of fulcra in front. Dorsal and anal fins approximate
+to the caudal. Gill-membranes confluent at the throat and attached to
+the isthmus. Branchiostegals none. Gills four; two accessory gills.
+Air-bladder large, simple, communicating with the dorsal wall of the
+œsophagus.</i></p>
+
+  <div class="figcenter" id="fig142" style="max-width: 393px">
+     <img
+    class="p1"   
+    src="images/fig142.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 142.—Tail of Acipenser. <i>a</i>, Fulcra;
+<i>b</i>, osseous bucklers.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_361">[361]</span></p>
+
+<p>Sturgeons are, perhaps, the geologically youngest Ganoids, evidence
+of their existence not having been met with hitherto in formations
+of older date than the Eocene clay of Sheppey. They are exclusively
+inhabitants of the temperate zone of the Northern Hemisphere, being
+either entirely confined to fresh water, or passing, for the purpose of
+spawning, a part of the year in rivers. They grow to a large size, and
+are the largest fishes of the fresh waters of the Northern Hemisphere,
+specimens 10 feet long being of common occurrence. The ova are very
+small, and so numerous that one female has been calculated to produce
+about three millions at one season; therefore their propagation, as
+well as their growth, must be very rapid; and although in many rivers
+their number is annually considerably thinned by the systematic manner
+in which they are caught when they ascend the rivers in shoals from the
+sea, no diminution has been observed. Wherever they occur they prove
+to be most valuable on account of their wholesome flesh. In Russia,
+besides, two not unimportant articles of trade are obtained from them,
+viz. Caviare, which is prepared from their ovaries, and Isinglass,
+which is made from the inner coats of their air-bladder. True Sturgeons
+are divided into two genera, <i>Acipenser</i> and <i>Scaphirhynchus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acipenser.</span>—The rows of osseous bucklers are not
+confluent on the tail. Spiracles present. Caudal rays
+surrounding the extremity of the tail.</p>
+</div>
+
+<p>About twenty different species of Sturgeons may be distinguished
+from European, Asiatic, and American rivers. The best known are the
+Sterlet (<i>A. ruthenus</i>) from Russian rivers, celebrated for the
+excellency of its flesh, but rarely exceeding a length of three feet;
+the Californian Short-snouted Sturgeon (<i>A. brachyrhynchus</i>);
+the Hausen (<i>A. huso</i>), from rivers, falling into the Black Sea
+and the Sea of Azow (rare in Mediterranean), sometimes 12 feet long,
+and yielding an inferior kind of isinglass; the Chinese Sturgeon
+(<i>A. sinensis</i>);<span class="pagenum" id="Page_362">[362]</span> the Common Sturgeon of the United States (<i>A.
+maculosus</i>), which sometimes crosses the Atlantic to the coasts of
+Great Britain; Güldenstædt’s Sturgeon (<i>A. güldenstædtii</i>), common
+in European and Asiatic rivers, which yields more than one-fourth of
+the caviare and isinglass exported from Russia; the Common Sturgeon
+of Western Europe (<i>A. sturio</i>), which attains to a length of 18
+feet, and has established itself also on the coasts of Eastern North
+America.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scaphirhynchus.</span>—Snout spatulate; posterior part of the
+tail attenuated and depressed, so that it is entirely enveloped
+by the osseous scutes. Spiracles none. The caudal rays do not
+extend to the extremity of the tail, which terminates in a
+filament.</p>
+</div>
+
+<p>Four species are known: one (<i>S. platyrhynchus</i>) from the
+river-system of the Mississippi, and the three others from Central
+Asia; all are exclusively freshwater fishes; their occurrence in so
+widely distant rivers is one of the most striking instances by which
+the close affinity of the North American and North Asiatic faunas is
+proved.</p>
+
+
+<h6 class="smcap">Second Family—Polyodontidæ.</h6>
+
+<p><i>Body naked, or with minute stellate ossifications. Mouth lateral,
+very wide, with minute teeth in both jaws. Barbels none. Caudal fin
+with fulcra. Dorsal and anal fins approximate to the caudal. Four gills
+and a half; no opercular gill or pseudobranchia.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Polyodon</span> (<span class="smcap">Spatularia</span>).—The snout is produced
+into an exceedingly long, shovel-like process, thin and flexible
+on the sides. Spiracles present. Gill-cover terminating in
+a very long tapering flap. One broad branchiostegal. Each
+branchial arch with a double series of very long, fine, and
+numerous gill-rakers, the two series being divided by a broad
+membrane. Air-bladder cellular. Upper caudal fulcra narrow,
+numerous.</p>
+</div>
+
+<p>The single species, <i>P. folium</i>, occurs in the Mississippi,<span class="pagenum" id="Page_363">[363]</span> and
+grows to a length of about six feet, of which the rostral shovel takes
+about one-fourth; in young examples it is comparatively still longer.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Psephurus</span> differs from <i>Polyodon</i> in having the
+rostral process less depressed and more conical. The gill-rakers
+are comparatively short, in moderate number, and distant from
+one another. Upper caudal fulcra enormously developed, and in
+small number (six).</p>
+</div>
+
+<p><i>Psephurus gladius</i> inhabits the Yan-tse-Kiang and Hoangho, the
+distribution of the <i>Polyodontidæ</i> being perfectly analogous to
+that of <i>Scaphirhynchus</i>. It grows to an immense size, specimens
+of 20 feet in length being mentioned by Basilewsky. The function of the
+rostral process in the economy of these fishes is not yet sufficiently
+explained. Martens believes that it serves as an organ of feeling,
+the water of those large Asiatic and American rivers being too turbid
+to admit of the Sturgeon seeing its prey, which consists of other
+fishes. The eyes of <i>Psephurus</i>, as well as <i>Polyodon</i>, are
+remarkably small. Both fishes are used as food.</p>
+
+  <div class="figcenter" id="fig143" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig143.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 143.—Psephurus gladius.</p>
+  </div>
+
+<p>Allied to the <i>Polyodontidæ</i>, and likewise provided with a
+paddle-shaped production of the fore part of the head, is the fossil
+genus <i>Chondrosteus</i>, remains of which occur in the Lias.</p>
+
+
+<h5 class="smaller">FIFTH SUB-ORDER—POLYPTEROIDEI.</h5>
+
+<p><i>Paired fins with axial skeleton, fringed; dorsal fins two or more.
+Branchiostegals absent, but generally gular plates. Vertebral column
+diphycercal or heterocercal. Body scaly.</i></p>
+
+<p><span class="pagenum" id="Page_364">[364]</span></p>
+
+
+<h6 class="smcap">First Family—Polypteridæ.</h6>
+
+<p><i>Scales ganoid; fins without fulcra. A series of dorsal spines, to
+each of which an articulated finlet is attached; anal placed close to
+the caudal fin, the vent being near the end of the tail. Abdominal
+portion of the vertebral column much longer than the caudal.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Polypterus.</span>—Teeth rasp-like, in broad bands in the
+jaws, on the vomer and palatine bones; jaws with an outer series
+of closely-set, larger, pointed teeth. Caudal fin surrounding
+the extremity of the vertebral column; ventral fins well
+developed. A spiracle on each side of the parietal, covered
+with an osseous plate. A single large gular plate. Air-bladder
+double, communicating with the ventral wall of the pharynx.</p>
+</div>
+
+  <div class="figcenter" id="fig144" style="max-width: 741px">
+     <img
+    class="p1"   
+    src="images/fig144.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 144.—Polypterus bichir.</p>
+  </div>
+
+<p>This Ganoid is confined to tropical Africa, occurring in abundance in
+the rivers of the west coast and in the Upper Nile; but it has not
+been found in the river-systems belonging to the Indian Ocean. It is
+scarce in the Middle and Lower Nile, and the specimens found below the
+Cataracts have been carried down, from southern latitudes, and do not
+propagate their species in that part of the river. There is only one
+species known, <i>Polypterus bichir</i> (“Bichir” being its vernacular
+name in Egypt), which varies in the number of the dorsal finlets,
+the lowest being eight, the highest eighteen. It attains to a length
+of four feet. Nothing is known of its mode of life, and observations
+thereon are very desirable.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Calamoichthys.</span>—Distinguished from <i>Polypterus</i> by
+its greatly elongate form, and the absence of ventral fins.</p>
+</div>
+
+<p><i>C. calabaricus</i>, a dwarf form from Old Calabar.</p>
+
+<p><span class="pagenum" id="Page_365">[365]</span></p>
+
+
+<h6 class="smcap">Second Family—Saurodipteridæ.</h6>
+
+<p><i>Scales ganoid, smooth like the surface of the skull. Two
+dorsal fins; paired fins obtusely lobate. Teeth conical. Caudal
+heterocercal.</i></p>
+
+<p>Extinct. <i>Diplopterus</i>, <i>Megalichthys</i>, and <i>Osteolepis</i>
+from Devonian and Carboniferous formations.</p>
+
+
+<h6 class="smcap">Third Family—Coelacanthidæ.</h6>
+
+<p><i>Scales cycloid. Two dorsal fins, each supported by a single
+two-pronged interspinous bone; paired fins obtusely lobate. Air-bladder
+ossified; notochord persistent, diphycercal.</i></p>
+
+<p>Extinct. <i>Coelacanthus</i> from carboniferous strata; several other
+genera, from the coal formations to the chalk, have been associated
+with it—<i>Undina</i>, <i>Graphiurus</i>, <i>Macropoma</i>,
+<i>Holophagus</i>, <i>Hoplopygus</i>, <i>Rhizodus</i>.</p>
+
+
+<h6 class="smcap">Fourth Family—Holoptychiidæ.</h6>
+
+<p><i>Scales cycloid or ganoid, sculptured. Two dorsal fins; pectorals
+narrow, acutely lobate; dentition dendrodont.</i></p>
+
+<p>Extinct. In this family a peculiar type of dentition is found—the
+jaws are armed with two kinds of teeth, small ones serially arranged,
+and much larger fang-like teeth disposed at long intervals. Both
+kinds show at their base in transverse sections a labyrinthic
+complexity of structure, numerous fissures radiating from the central
+mass of vasodentine which fills up the pulp cavity, and sending
+off small ramifying branches. Genera belonging to this family
+are <i>Holoptychius</i>, <i>Saurichthys</i>, <i>Glyptolepis</i>,
+<i>Dendrodus</i>, <i>Glyptolaemus</i>, <i>Glyptopomus</i>,
+<i>Tristichopterus</i>, <i>Gyroptychius</i>, <i>Strepsodus</i>, from
+Devonian and Carboniferous strata.</p>
+
+<p><span class="pagenum" id="Page_366">[366]</span></p>
+
+
+<h5 class="smaller">SIXTH SUB-ORDER—PYCNODONTOIDEI.</h5>
+
+<p><i>Body compressed, high and short or oval, covered with rhombic scales
+arranged in decussating pleurolepidal lines. Notochord persistent.
+Paired fins without axial skeleton. Teeth on the palate and hinder part
+of the lower jaw molar-like. Branchiostegals, but no gular plates.</i></p>
+
+<p>Extinct. The regular lozenge-shaped pattern of the integuments of these
+fishes is described by Sir P. Egerton thus: “Each scale bears upon its
+inner anterior margin a thick solid bony rib, extending upwards beyond
+the margin of the scale, and sliced off obliquely, above and below, on
+opposite sides, for forming splices with the corresponding processes
+of the adjoining scales. These splices are so closely adjusted that,
+without a magnifying power or an accidental dislocation, they are not
+perceptible. When <i>in situ</i>, and seen internally, these continuous
+lines decussate with the true vertebral apophyses.” In some genera the
+“pleurolepidal” lines are confined to the anterior part of the side.</p>
+
+
+<h6 class="smcap">First Family—Pleurolepidæ.</h6>
+
+<p><i>Homocercal. Body less high. Fins with fulcra.</i></p>
+
+<p><i>Pleurolepis</i> and <i>Homoeolepis</i> from the Lias.</p>
+
+
+<h6 class="smcap">Second Family—Pycnodontidæ.</h6>
+
+<p><i>Homocercal. The neural arches and ribs are ossified; the roots of
+the ribs are but little expanded in the older genera, but enlarged in
+the tertiary forms, so as to simulate vertebræ. Paired fins not lobate.
+Obtuse teeth on the palate and the sides of the mandible; maxilla
+toothless; incisor-like teeth in the intermaxillary and front of the
+mandible. Fulcra absent in all the fins.</i></p>
+
+<p>These fishes abound in Mesozoic and Tertiary formations.<span class="pagenum" id="Page_367">[367]</span>
+<i>Gyrodus</i>, <i>Mesturus</i>, <i>Microdon</i>, <i>Coelodus</i>,
+<i>Pycnodus</i>, <i>Mesodon</i>, are some of the genera distinguished
+by palæontologists. (See Fig. <a href="#fig102">102</a>, p. 201.)</p>
+
+
+<h5 class="smaller">SEVENTH SUB-ORDER—LEPIDOSTEOIDEI.</h5>
+
+<p><i>Scales ganoid, rhombic; fins generally with fulcra; paired fins
+not lobate. Præ- and inter-operculum developed; generally numerous
+branchiostegals, but no gular plate.</i></p>
+
+
+<h6 class="smcap">First Family—Lepidosteidæ.</h6>
+
+<p><i>Scales ganoid, lozenge-shaped. Skeleton completely ossified;
+vertebræ convex in front and concave behind. Fins with fulcra; dorsal
+and anal composed of articulated rays only, placed far backwards, close
+to the caudal. Abdominal part of the vertebral column much longer
+than caudal. Branchiostegals not numerous, without enamelled surface.
+Heterocercal.</i></p>
+
+<div class="blockquot">
+
+<p><i>Lepidosteus.</i>—Body elongate, sub-cylindrical; snout
+elongate, spatulate, or beak-shaped; cleft of the mouth wide;
+both jaws and palate armed with bands of rasp-like teeth and
+series of larger conical teeth. Four gills; no spiracles; three
+branchiostegals. Air-bladder cellular, communicating with the
+pharynx.</p>
+</div>
+
+  <div class="figcenter" id="fig145" style="max-width: 631px">
+     <img
+    class="p1"   
+    src="images/fig145.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 145.—Lepidosteus viridis.</p>
+  </div>
+
+<p>Fishes of this genus existed already in Tertiary times; their remains
+have been found in Europe as well as North America. In our period
+they are limited to the temperate parts of North America, Central
+America, and Cuba. Three species can be distinguished which attain
+to a length of about six feet. They feed on other fishes, and their
+general resemblance to a pike has given to them the vernacular names of
+“Gar-Pike,” or “Bony Pike.”</p>
+
+<p><span class="pagenum" id="Page_368">[368]</span></p>
+
+
+<h6 class="smcap">Second Family—Sauridæ.</h6>
+
+<p><i>Body oblong, with ganoid scales; vertebræ not completely ossified;
+termination of the vertebral column homocercal; fins generally with
+fulcra. Maxillary composed of a single piece; jaws with a single series
+of conical pointed teeth. Branchiostegals numerous, enamelled, the
+anterior broad gular plates.</i></p>
+
+<p>Extinct. Numerous genera occur in Mesozoic formations; one with the
+widest range is <i>Semionotus</i>, with distichous fulcra, from the
+Lias and Jura; <i>Eugnathus</i>, with large posteriorly serrated
+scales, and fulcra on nearly all fins; <i>Cephenoplosus</i> from the
+Upper Lias; <i>Macrosemius</i> from the Oolite; <i>Propterus</i>,
+<i>Ophiopsis</i>, <i>Pholidophorus</i>, <i>Pleuropholis</i>,
+<i>Pachycormus</i>, <i>Oxygnathus</i>, <i>Ptycholepis</i>,
+<i>Conodus</i>, <i>Eulepidotus</i>, <i>Lophiostomus</i>, etc.</p>
+
+
+<h6 class="smcap">Third Family—Stylodontidæ.</h6>
+
+<p><i>Body rhombic or ovate, with ganoid scales; vertebræ not completely
+ossified; termination of the vertebral column homocercal; fins with
+fulcra. Maxillary composed of a single piece; jaws with several series
+of teeth, the outer ones equal, styliform. Dorsal fin very long,
+extending to the caudal. Branchiostegals numerous.</i></p>
+
+<p>Extinct. <i>Tetragonolepis</i> from the Lias (see Fig. <a href="#fig103">103</a>, p. 207).</p>
+
+
+<h6 class="smcap">Fourth Family—Sphærodontidæ.</h6>
+
+<p><i>Body oblong, with rhombic ganoid scales; vertebræ ossified, but not
+completely closed; homocercal; fins with fulcra. Maxillary composed of
+a single piece; teeth in several series, obtuse; those on the palate
+globular. Dorsal and anal fins short. Branchiostegals.</i></p>
+
+<p>Extinct. The type genus of this family is <i>Lepidotus</i>, so named
+from its large rhombic, dense, and polished scales.<span class="pagenum" id="Page_369">[369]</span> The dorsal is
+opposite to the anal, and all the fins are provided with a double row
+of fulcra. This genus ranges from the Lias to the Chalk; one species
+would seem to have survived into tertiary times, if it should not prove
+to be a <i>Lepidosteus</i>.</p>
+
+
+<h6 class="smcap">Fifth Family—Aspidorhynchidæ.</h6>
+
+<p><i>Body elongate, with ganoid scales; jaws prolonged into a beak;
+termination of the vertebral column homocercal. Fins with fulcra;
+a series of enlarged scales along the side of the body. Dorsal fin
+opposite to the anal.</i></p>
+
+  <div class="figcenter" id="fig146" style="max-width: 561px">
+     <img
+    class="p1"   
+    src="images/fig146.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 146.—Aspidorhynchus fisheri, from the Purbeck
+beds; <i>m</i>, mandible; <i>a</i>, presymphyseal bone.</p>
+  </div>
+
+<p>Extinct; mesozoic. <i>Aspidorhynchus</i> has the upper jaw longer than
+the lower; very peculiar is the occurrence of a single, solid, conical
+bone, situated in front of the symphysis of the lower jaw, to which
+it is joined by a suture. <i>Belonostomus</i> with both jaws of equal
+length.</p>
+
+
+<h6 class="smcap">Sixth Family—Palæoniscidæ.</h6>
+
+<p><i>Body fusiform, with rhombic ganoid scales. Notochord persistent,
+with the vertebral arches ossified. Heterocercal. All the fins with
+fulcra; dorsal short. Branchiostegals numerous, the foremost pair
+forming broad gulars. Teeth small, conical, or cylindrical.</i></p>
+
+<p>Extinct. Many genera are known; from the Old Red<span class="pagenum" id="Page_370">[370]</span>
+Sandstone—<i>Chirolepis</i> and <i>Acrolepis</i>; from Carboniferous
+rocks—<i>Cosmoptychius</i>, <i>Elonichthys</i>, <i>Nematoptychius</i>,
+<i>Cycloptychius</i>, <i>Microconodus</i>, <i>Gonatodus</i>,
+<i>Rhadinichthys</i>, <i>Myriolepis</i>, <i>Urosthenes</i>; from the
+Permian—<i>Rhabdolepis</i>, <i>Palæoniscus</i>, <i>Amblypterus</i>
+and <i>Pygopterus</i>; from the Lias—<i>Centrolepis</i>,
+<i>Oxygnathus</i>, <i>Cosmolepis</i>, and <i>Thrissonotus</i>.</p>
+
+<div class="blockquot">
+
+<p>[See Traquair, “The Ganoid Fishes of the British Carboniferous
+Formations.” Part I. <i>Palæoniscidæ.</i>]</p>
+</div>
+
+
+<h6 class="smcap">Seventh Family—Platysomidæ.</h6>
+
+<p><i>Body generally high, compressed, covered with rhombic ganoid
+scales arranged in dorso-ventral bands. Notochord persistent, with
+the vertebral arches ossified. Heterocercal; fins with fulcra; dorsal
+fin long, occupying the posterior half of the back. Branchiostegals
+numerous. Teeth tubercular or obtuse.</i></p>
+
+<p>Extinct. From Carboniferous and Permian formations—<i>Eurynotus</i>,
+<i>Benedenius</i>, <i>Mesolepis</i>, <i>Eurysomus</i>,
+<i>Wardichthys</i>, <i>Chirodus</i> (M’Coy), <i>Platysomus</i>.</p>
+
+<p>
+[See Traquair, “On the Structure and Affinities of the Platysomidæ”, in
+“Trans. Roy. Soc.,” Edinb., vol. xxix.]
+</p>
+
+  <div class="figcenter" id="fig147" style="max-width: 436px">
+     <img
+    class="p1"   
+    src="images/fig147.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 147.—Platysomus gibbosus.</p>
+  </div>
+
+
+<h5 class="smaller">EIGHTH SUB-ORDER—AMIOIDEI.</h5>
+
+<p><i>Vertebral column more or less completely ossified, heterocercal.
+Body covered with cycloid scales. Branchiostegals present.</i></p>
+
+<p><span class="pagenum" id="Page_371">[371]</span></p>
+
+
+<h6 class="smcap">First Family—Caturidæ.</h6>
+
+<p><i>Notochord persistent, with partially ossified vertebræ; homocercal;
+fins with fulcra. Teeth in a single series, small, pointed.</i></p>
+
+<p>Extinct. <i>Caturus</i> from the Oolite to the Chalk.</p>
+
+  <div class="figcenter" id="fig148" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig148.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 148.—Caturus furcatus (Solenhofen).</p>
+  </div>
+
+
+<h6 class="smcap">Second Family—Leptolepidæ.</h6>
+
+<p><i>Scales cycloid. Vertebræ ossified; homocercal; fins without fulcra;
+dorsal short. Teeth minute, in bands, with canines in front.</i></p>
+
+<p>Extinct, and leading to the living representative of this suborder.
+<i>Thrissops</i> with the dorsal fin placed far backwards, and opposite
+to the long anal. <i>Leptolepis</i> with the dorsal fin opposite to
+the ventrals, from the Lias and Oolite. These fishes, as far as the
+preserved parts are concerned, cannot be distinguished from Teleosteous
+fishes, to which they are referred by some Palæontologists.</p>
+
+  <div class="figcenter" id="fig149" style="max-width: 661px">
+     <img
+    class="p1"   
+    src="images/fig149.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 149.—Leptolepis sprattiformis.</p>
+  </div>
+
+
+<h6 class="smcap">Third Family—Amiidæ.</h6>
+
+<p><i>Skeleton entirely ossified; a single large gular plate;
+homocercal;<span class="pagenum" id="Page_372">[372]</span> fins without fulcra; a long soft dorsal fin.
+Abdominal and caudal parts of the vertebral column subequal in extent.
+Branchiostegals numerous.</i></p>
+
+  <div class="figcenter" id="fig150" style="max-width: 701px">
+     <img
+    class="p1"   
+    src="images/fig150.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 150.—Amia calva; <i>g</i>, gular plate.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Amia.</span>—Body rather elongate, sub-cylindrical,
+compressed behind. Snout short, cleft of the mouth of moderate
+width. Jaws with an outer series of closely-set pointed teeth,
+and with a band of rasp-like teeth; similar teeth on the
+vomer, palatine, and pterygoid bones. Anal short; caudal fin
+rounded. Gills four; air-bladder bifurcate in front, cellular,
+communicating with the pharynx.</p>
+</div>
+
+<p>The “Bow-fin” or “Mud-fish” (<i>A. calva</i>) is not uncommon in many
+of the fresh waters of the United States; it grows to a length of two
+feet. Little is known about its habits; small fish, crustaceans, and
+aquatic insects, have been found in its stomach. Wilder has observed
+its respiratory actions; it rises to the surface, and, without emitting
+any air-bubble whatever, opens the jaws widely, and apparently gulps in
+a large quantity of air; these acts of respiration are more frequently
+performed when the water is foul or has not been changed; and there
+is no doubt that an exchange of oxygen and carbonic acid is effected,
+as in the lungs of aërial vertebrates. The flesh of this fish is not
+esteemed.</p>
+
+<p>Fossil remains occur in tertiary deposits of North America, for
+instance in the Wyoming territory; they have been distinguished as
+<i>Protamia</i> and <i>Hypamia</i>.</p>
+
+<p><span class="pagenum" id="Page_373">[373]</span></p>
+
+
+<h3 class="smaller">SECOND SUB-CLASS—TELEOSTEI.</h3>
+
+<p><i>Heart with a non-contractile bulbus arteriosus; intestine without
+spiral valve; optic nerves decussating; skeleton ossified, with
+completely formed vertebræ; vertebral column diphycercal or homocercal;
+branchiæ free.</i><a id="FNanchor_40" href="#Footnote_40" class="fnanchor">[40]</a></p>
+
+<p>The Teleostei form the majority of the fishes of the present fauna, and
+are the geological successors of the Palæichthyes, undoubted Teleostei
+not ranging farther back than the Chalk. This sub-class comprises an
+infinite variety of forms; and as, naturally, many Ganoid fishes lived
+under similar external conditions, and led a similar mode of life as
+certain Teleostei, we find not a few analogous forms in both series:
+some Ganoids resembling externally the Teleosteous Siluroids, others
+the Clupeoids, others the Chætodonts, others the Scombresoces, etc.
+But there is no direct genetic relation between those fishes, as some
+Naturalists were inclined to believe.</p>
+
+<p>The Teleostei are divided into six orders:—</p>
+
+<div class="blockquot">
+
+<p>A. <span class="smcap">Acanthopterygii.</span>—Part of the rays of the dorsal,
+anal, and ventral fins not articulated, spines. The lower
+pharyngeals separate. Air-bladder, if present, without pneumatic
+duct in the adult.</p>
+
+<p>B. <span class="smcap">Acanthopterygii pharyngognathi.</span>—Part of the rays of
+the dorsal, anal, and ventral fins not articulated, spines. The
+lower pharyngeals coalesced. Air-bladder without pneumatic duct.</p>
+
+<p><span class="pagenum" id="Page_374">[374]</span></p>
+
+<p><span class="smcap">C. Anacanthini.</span>—Vertical and ventral fins without
+spinous rays. Ventral fins, if present, jugular or thoracic.
+Air-bladder, if present, without pneumatic duct. Lower
+pharyngeals separate.</p>
+
+<p><span class="smcap">D. Physostomi.</span>—All the fin rays articulated; only the
+first of the dorsal and pectoral fins is sometimes ossified.
+Ventral fins, if present, abdominal, without spine. Air-bladder,
+if present, with a pneumatic duct.</p>
+
+<p><span class="smcap">E. Lophobranchii.</span>—Gills not laminated, but composed
+of small rounded lobes, attached to the branchial arches.
+Gill-cover reduced to a large simple plate. A dermal skeleton
+replaces more or less soft integuments.</p>
+
+<p><span class="smcap">F. Plectognathi.</span>—A soft dorsal fin opposite to the
+anal; sometimes elements of a spinous dorsal. Ventral fins none,
+or reduced to spines. Gills pectinate; air-bladder without
+pneumatic duct. Skin with rough scutes, or with spines, or naked.</p>
+</div>
+
+
+<h4 class="smaller">FIRST ORDER—ACANTHOPTERYGII.</h4>
+
+<p><i>Part of the rays of the dorsal, anal, and ventral fins are not
+articulated, more or less pungent spines. The lower pharyngeals are
+generally separate. Air-bladder, if present, without pneumatic duct in
+the adult.</i><a id="FNanchor_41" href="#Footnote_41" class="fnanchor">[41]</a></p>
+
+
+<h5 class="smcap smaller">First Division—Acanthopterygii Perciformes.</h5>
+
+<p><i>Body more or less compressed, elevated or oblong, but not elongate;
+the vent is remote from the extremity of the tail, behind the ventral
+fins if they are present. No prominent anal papilla. No superbranchial
+organ. Dorsal fin or fins occupying the<span class="pagenum" id="Page_375">[375]</span> greater portion of the
+back; spinous dorsal well developed, generally with stiff spines, of
+moderate extent, rather longer than, or as long as, the soft; the soft
+anal similar to the soft dorsal, of moderate extent or rather short.
+Ventrals thoracic, with one spine and with four or five rays.</i></p>
+
+
+<h6 class="smcap">First Family—Percidæ.</h6>
+
+<p><i>The scales extend but rarely over the vertical fins, and the lateral
+line is generally present, continuous from the head to the caudal fin.
+All the teeth simple and conical; no barbels. No bony stay for the
+præoperculum.</i></p>
+
+<p>A large family, represented by numerous genera and species in fresh
+waters, and on all the coasts of the temperate and tropical regions.
+Carnivorous.</p>
+
+<p>Fossil Percoids abound in some formations, for instance, at Monte
+Bolca, where species of <i>Labrax</i>, <i>Lates</i>, <i>Smerdis</i>
+and <i>Cyclopoma</i> (both extinct), <i>Dules</i>, <i>Serranus</i>,
+<i>Apogon</i>, <i>Therapon</i>, and <i>Pristipoma</i> have been
+recognised. <i>Paraperca</i> is a genus recently discovered in the
+Marles of Aix-en-Provence. A species of <i>Perca</i> is known from the
+freshwater deposit of Oeningen.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Perca.</span>—All the teeth are villiform, without canines;
+teeth on the palatine bones and vomer; tongue toothless. Two
+dorsal fins, the first with thirteen or fourteen spines; anal
+fin with two spines. Præoperculum and præorbital serrated.
+Scales small; head naked above. Branchiostegals seven. Vertebræ
+more than twenty-four.</p>
+</div>
+
+<p>The “Freshwater Perch” (<i>Perca fluviatilis</i>) is too familiarly
+known to require description. It is generally distributed over Europe
+and Northern Asia; and equally common in North America, there being
+no sufficient ground for separating specifically the specimens of the
+Western Hemisphere. It frequents especially still waters, and sometimes
+descends into brackish water. Its weight does not seem to exceed<span class="pagenum" id="Page_376">[376]</span> 5
+lbs. The female deposits her ova, united together by a viscid matter,
+in lengthened or net-shaped bands, on waterplants. The number of the
+eggs of one spawn may exceed a million. Two other species, <i>P.
+gracilis</i>, from Canada, and <i>P. schrenckii</i>, from Turkestan,
+have been distinguished, but they are very imperfectly known. An allied
+genus is <i>Siniperca</i>, from Northern China.</p>
+
+  <div class="figcenter" id="fig151" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig151.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 151.—Perca fluviatilis, the Perch.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Percichthys.</span>—Differing from <i>Perca</i> especially in
+the number of the fin-spines, which are nine or ten in the first
+dorsal, and three in the anal fin. The upper surface of the head
+scaly.</p>
+</div>
+
+<p>These fishes represent the Freshwater Perches of the Northern
+Hemisphere in the fresh waters of the temperate parts of South America.
+Two species have been described from Patagonia, and one or two from
+Chili and Peru.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Labrax.</span>—All the teeth are villiform, without canines;
+teeth on the palatine bones, vomer, and the tongue. Two dorsal
+fins, the first with nine spines; anal fin generally with three.
+Præoperculum serrated, and with denticulations along its lower
+limb; præorbital with the margin entire. Scales rather small.
+Branchiostegals seven; well developed pseudobranchiæ.</p>
+</div>
+
+<p>The “Bass” are fishes common on the coasts of Europe and the Atlantic
+coasts, and in the fresh waters of the United States and Canada. The
+three European species are almost exclusively inhabitants of the sea,
+entering brackish, but never fresh waters, whilst the American species,
+the number<span class="pagenum" id="Page_377">[377]</span> of which is still uncertain, seem to affect principally
+fresh water, although some are also found in the sea. The best known
+European species is <i>Labrax lupus</i> (see p. 41, Fig. <a href="#fig4">4</a>), common on
+the British coasts. It is a voracious fish, with a remarkably large
+stomach, and received from the ancient Romans the appropriate name of
+<i>lupus</i>. By the Greeks it was so highly esteemed that Archestratus
+termed this or one of the two other closely-allied species, taken near
+Milet, “offspring of the gods.” They attributed to it a tender regard
+for its own safety; and Aristotle says that it is the most cunning of
+fishes; and that, when surrounded by the net, it digs for itself a
+channel of escape through the sand. Specimens of from two to three feet
+are not scarce, but its flesh is nowadays much less esteemed than in
+ancient times. Of the North American species <i>Labrax lineatus</i> and
+<i>Labrax rufus</i> are the most common.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lates.</span>—All the teeth are villiform, without canines;
+teeth on the palatine bones and vomer, but none on the tongue.
+Two dorsal fins—the first with seven or eight, the anal fin
+with two or three, spines. Præoperculum with strong spines at
+the angle and the lower limb; also the præorbital is strongly
+serrated. Scales of moderate size. Branchiostegals seven;
+pseudobranchiæ present.</p>
+</div>
+
+<p>Three well-known species belong to this genus. The Perch of the
+Nile and other rivers of tropical Africa (<i>Lates niloticus</i>);
+the Perch of the Ganges and other East Indian rivers, which enters
+freely brackish water, and extends to the rivers of Queensland
+(<i>Lates calcarifer</i>). These two species attain to a large size,
+the Indian species to a length of five feet. Hamilton says that “the
+vulgar English in Calcutta call it ‘Cockup,’ and that it is one of
+the lightest and most esteemed foods brought to table in that city.”
+Specimens two feet in length and caught in salt water are by far the
+best quality. The third species (<i>Lates colonorum</i>) is found in<span class="pagenum" id="Page_378">[378]</span>
+Australia only, and does not appear to grow to the same large size as
+its congeners.</p>
+
+<p>Allied to <i>Lates</i> is <i>Psammoperca</i> from Australia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Percalabrax.</span>—All the teeth villiform, without canines;
+teeth on the palatine bones and vomer, but none on the tongue.
+Two dorsal fins—the first with eleven, the anal fin with three
+spines. Præoperculum serrated along its hinder margin, and with
+strong spinous teeth below; præorbital not serrated. Scales
+rather small. Branchiostegals seven; pseudobranchiæ present.</p>
+</div>
+
+<p>This Perch (<i>Percalabrax japonicus</i>) is one of the most common
+fishes on the coasts of China, Japan, and Formosa; the Japanese name it
+“Zuzuki,” or “Seengo.”</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acerina.</span>—All the teeth villiform, without canines;
+teeth on the vomer, but none on the palatine bones or the
+tongue. One continuous dorsal fin, of which the spinous portion
+consists of from thirteen to nineteen spines; two anal spines.
+Body rather low, with rather small scales. Bones of the skull
+with wide muciferous cavities; præoperculum denticulated.</p>
+</div>
+
+<p>Small freshwater perches, of which <i>A. cernua</i>, named “Pope” in
+England, is the most common, and has the widest distribution in Central
+Europe and Siberia. The two other species have a more restricted range,
+<i>A. schrætzer</i> being confined to the Danube and other rivers
+emptying into the Black Sea; and <i>A. czekanowskii</i> to Siberian
+rivers. This genus is not represented in the Western Hemisphere.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lucioperca.</span>—Teeth in villiform bands, those in the
+jaws with additional canines; palatine bones toothed. Two dorsal
+fins—the first with from twelve to fourteen, the anal fin with
+two spines. Præoperculum serrated; scales small.</p>
+</div>
+
+<p>The “Pike-Perches” are inhabitants of many lakes and rivers of the
+temperate northern zone. The European species is confined to the
+eastern two-thirds of the continent, and one of the most esteemed
+freshwater fishes; it attains to a length of three or four feet,
+and to a weight of from 25 to 30 lbs.<span class="pagenum" id="Page_379">[379]</span> It has been recommended for
+acclimatisation in England, and there is no doubt that in certain
+localities it might prove a valuable addition to the native fauna; but
+like all its congeners it is very voracious and destructive to smaller
+fishes. Two other species inhabit rivers of European and Asiatic
+Russia, and two or three the fresh waters of North America.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pileoma.</span>—All the teeth minute, villiform, without
+canines; teeth on the vomer and palatine bones. Two dorsal
+fins—the first with fourteen or fifteen spines. Body rather
+elongate, with small scales. Præoperculum not serrated.</p>
+</div>
+
+<p>Small freshwater perches abundant in the United States. Like the
+following genus, and some others which need not be mentioned here,
+they can be regarded as small, dwarfed representatives of the
+preceding genera. The species seem to be numerous, but have not yet
+been sufficiently well distinguished. The latest and best account of
+them is by L. Vaillant, “Recherches sur les Poissons d’eaux douces de
+l’Amérique septentrionale (<i>Etheostomatidæ</i>),” in Nouv. Archiv. du
+Muséum d’Hist. Nat. de Paris, ix., 1873.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Boleosoma.</span>—Allied to <i>Pileoma</i>, but with only
+nine or ten feeble spines in the first dorsal fin. North America.</p>
+</div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aspro.</span>—Body elongate, cylindrical; snout thick,
+projecting beyond the mouth, which is situated at its lower
+side. All the teeth villiform, without canines; teeth on the
+vomer and palatine bones. Two separate dorsals. Præoperculum
+serrated; præorbital entire. Scales small.</p>
+</div>
+
+<p>Two small Perches from the Danube and some other rivers of the
+continent of Europe, <i>Aspro vulgaris</i> and <i>A. zingel</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centropomus.</span>—Body oblong, compressed, with scales of
+moderate size. All the teeth villiform, without canines; teeth
+on the vomer and palatine bones. Two dorsal fins, the first with
+eight strong spines, the anal with three, the second of which is
+very strong and long. Præoperculum with a double denticulated
+edge.</p>
+</div>
+
+<p><span class="pagenum" id="Page_380">[380]</span></p>
+
+<p>Numerous species are known from the West Indies and Central America.
+These fishes are found in fresh, brackish, and salt water, and some of
+the species indiscriminately enter all three kinds of water. They do
+not grow to any large size, but are esteemed as food.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Enoplosus.</span>—Body much elevated, the depth being still
+more increased by the high vertical fins. All the teeth are
+villiform, without canines; teeth on the vomer, palatine bones,
+and the tongue. Two dorsal fins, the first with seven spines.
+Præoperculum serrated, with spinous teeth at the angle. Scales
+of moderate size.</p>
+</div>
+
+<p>A small and very common marine species (<i>E. armatus</i>) on the coast
+of Australia, especially New South Wales. It is readily recognised by
+the peculiar shape of its body, and eight black transverse bands on a
+whitish ground.</p>
+
+<hr class="tb">
+
+<p>This, and the preceding genus, leads to the true “Sea perches,” which
+never, or but rarely, enter fresh water:—</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centropristis.</span>—Body oblong, with scales of small or
+moderate size. Teeth villiform, with small canines in both jaws;
+vomerine teeth placed in an angular band, or a short triangular
+patch; teeth on the palatine bones, but none on the tongue.
+One dorsal, with the formula 10/12 or less; anal fin 3/7(6).
+Præoperculum serrated; sometimes with the angle projecting, and
+armed with long spines.</p>
+</div>
+
+<p>About twenty species of small size are known from temperate and
+tropical seas.</p>
+
+<p><span class="smcap">Anthias.</span>—Body rather short, compressed, with scales of
+moderate size. Teeth villiform, with small canines in both jaws; teeth
+on the vomer, and palatine teeth. One dorsal, generally with ten
+spines; anal fin with three; caudal forked. The rays of one or more
+fins may be prolonged. Præoperculum serrated.</p>
+
+<p>About twenty species are known from temperate and tropical seas; they
+are mostly of small size, and agreeably coloured, pink and yellow
+being the predominant colours. <i>Anthias sacer</i> is common in the
+Mediterranean, and was well<span class="pagenum" id="Page_381">[381]</span> known to the ancients. Aristotle says that
+the fishers of Sponges call it sacred, because no voracious fishes came
+to the places which it frequented, and the diver might descend with
+safety.—<i>Callanthias</i> is a genus closely allied to <i>Anthias</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Serranus.</span>—Body oblong, compressed, with small scales.
+Teeth villiform, with very distinct canines in both jaws;
+teeth on the vomer and palatine bones, none on the tongue. One
+dorsal, mostly with nine or eleven, rarely with eight, ten or
+twelve spines; anal fin with three: all the spines being stout.
+Præoperculum serrated behind and at the angle, but not below.</p>
+</div>
+
+  <div class="figcenter" id="fig152" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig152.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 152.—Serranus altivelis.</p>
+  </div>
+
+<p>The “Sea perches proper” are found on the shores of all temperate and
+tropical seas, most abundantly in the latter. A few species enter
+brackish and even fresh water, one having been found as high up the
+Ganges as the confines of Nepal. However, all spawn in the sea. The
+variety of species is almost infinite, about 150 being tolerably
+well known, and many more having been described. The distinction of
+the species is most difficult, and nearly impossible to those who
+have no opportunity of closely and long observing them in nature,
+as they are not only subject to great variation of colour, but also
+to considerable changes dependent on age. Many are most agreeably
+coloured, and ornamented with spots, or cross bands or longitudinal
+stripes; colours which become more uniform with age in those species
+which attain to a<span class="pagenum" id="Page_382">[382]</span> large size. The majority remain of rather small
+size, growing to a length of one or two feet; but not a few reach more
+than twice that length, and may even become dangerous to man. Instances
+of bathers having been attacked by a gigantic species not uncommon at
+the Seychelles and Aden are on record, the persons having died from the
+injuries received. Almost all the species are eatable, and many are
+esteemed as food. One species is common on the British coasts (<i>S.
+cabrilla</i>), and probably some of the more southern species (<i>S.
+scriba</i> and <i>S. gigas</i>) occasionally wander as far northwards
+as the British Channel. The species figured, <i>S. altvelis</i>, is
+locally distributed over nearly all the tropical parts of the Indian
+Ocean, and distinguished by particularly high dorsal and anal fins.
+<i>Anyperodon</i> and <i>Prionodes</i> are two genera closely allied to
+<i>Serranus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Plectropoma.</span>—Form of the body and dentition (see
+p. 127, Fig. <a href="#fig54">54</a>) similar to that of <i>Serranus</i>, with a
+præoperculum serrated behind, and armed with spinous teeth
+below, which are directed forwards. Dorsal fin with from seven
+to thirteen spines.</p>
+</div>
+
+<p>About thirty species from tropical seas are known. <i>Trachypoma</i> is
+allied to this genus.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Polyprion.</span>—Body oblong, rather compressed, covered
+with small scales. All the teeth are villiform; teeth on the
+vomer, palatine bones, and the tongue. One dorsal with eleven
+or twelve spines; anal with three. Præoperculum denticulated; a
+strong, rough, longitudinal ridge on the operculum.</p>
+</div>
+
+<p>Two species are known: one from the European coasts (<i>P.
+cernium</i>), and one from Juan Fernandez (<i>P. kneri</i>). They
+attain to a weight of 80 lbs. and more. The European species has the
+habit of accompanying floating wood, to which they are attracted by
+the small marine species generally surrounding such objects, and
+affording a supply of food. It is known by the name of “Stone-bass,”
+and excellent eating.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Grammistes.</span>—Body rather short, compressed, covered
+with<span class="pagenum" id="Page_383">[383]</span> minute scales imbedded in the thick skin. All the teeth
+are villiform; teeth on the vomer and palatine bones. Two
+dorsal fins, the first with seven spines. Præoperculum without
+serrature, but with three short spines. A short skinny barbel is
+frequently developed at the chin.</p>
+</div>
+
+<p>Three species are known from the Indo-Pacific; they are of small
+size. One, <i>G. orientalis</i>, is black, with six or seven white
+longitudinal stripes, and one of the most common coast-fishes of that
+ocean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhypticus.</span>—Body oblong, compressed, covered with
+minute scales imbedded in the thick skin. All the teeth are
+villiform; teeth on the vomer and palatine bones. The spines
+of the vertical fins are but little developed, always in small
+number and short, and may disappear entirely. Præoperculum not
+serrated, with some obtuse spines.</p>
+</div>
+
+<p>Four species are known: three from the West Indies and one from the
+Galapagoes Islands.</p>
+
+<p>Other genera allied to the two preceding are <i>Aulacocephalus</i> from
+Mauritius, Reunion, and Japan; and <i>Myriodon</i> from the coasts of
+Australia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Diploprion.</span>—Body rather elevated, compressed, with
+small scales. All the teeth villiform; teeth on the vomer and
+palatine bones. Two dorsal fins, the first with eight spines;
+anal with two. Præoperculum with a double denticulated limb.</p>
+</div>
+
+  <div class="figcenter" id="fig153" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig153.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 153.—Mesoprion monostigma.</p>
+  </div>
+
+<p>The single species known (<i>D. bifasciatum</i>), is very common in
+the East Indian Archipelago, and on the coasts of<span class="pagenum" id="Page_384">[384]</span> Southern China
+and Japan. It is of small size, and ornamented with two broad black
+cross-bands.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Mesoprion.</span>—Body oblong, compressed, covered with
+scales of moderate size. Teeth villiform, with canines in both
+jaws; teeth on the vomer and palatine bones. One dorsal fin,
+with ten or eleven, rarely with more spines; anal fin with
+three. Præoperculum serrated; in some species (<i>Genyoroge</i>)
+a more or less distinct spinous knob projects from the surface
+of the interoperculum, and is received in a more or less deep
+notch of the præopercular margin.</p>
+</div>
+
+  <div class="figcenter" id="fig154" style="max-width: 338px">
+     <img
+    class="p1"   
+    src="images/fig154.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 154.—Opercles <i>a</i>, of <i>Mesoprion</i>;
+<i>b</i>, of <i>Genyoroge</i>; <i>o</i>, knob received in a notch of
+the præoperculum.</p>
+  </div>
+
+<p>About seventy species are known from tropical seas in both hemispheres,
+but it is noteworthy that the species with the peculiar protuberance
+of the interoperculum are confined to the Indo-Pacific. The coloration
+is much more simple than in the small-scaled Serrani, a uniform hue
+of greenish, pink, or red prevailing; species with longitudinal bands
+are scarce, but not rarely dark cross-bands or a large spot on the
+side occur. The majority of the species remain within very moderate
+dimensions, specimens exceeding three feet in length being scarce. They
+are generally eaten, and some of the species belong to the commonest
+fishes of the tropics, as <i>M. bengalensis</i>, <i>chrysurus</i>,
+<i>gembra</i>, <i>griseus</i>, and others.</p>
+
+<p><i>Glaucosoma</i> from Japan and Australia is allied to
+<i>Mesoprion</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Dules.</span>—Body oblong, compressed, with scales of
+moderate size, and very indistinctly ctenoid. All the teeth are
+villiform; teeth on the vomer and palatine bones. One dorsal
+with ten spines; anal fin with three. Præoperculum serrated. Six
+branchiostegals only.</p>
+</div>
+
+<p><span class="pagenum" id="Page_385">[385]</span></p>
+
+<p>About ten species are known, inhabiting fresh waters of the coasts of
+the Indo-Pacific, and being especially common in the islands of this
+region, and also in Tropical Australia. Some live also in brackish
+water. Though of small size they are esteemed as food.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Therapon.</span>—Body oblong, compressed, with scales of
+moderate size. All the teeth are villiform, those of the vomer
+and palatine bones being rudimentary, and frequently absent.
+One dorsal, with a depression in its upper margin, and twelve
+or thirteen spines; anal fin with three. Præoperculum serrated.
+Air-bladder with two divisions, an anterior and posterior. Six
+branchiostegals.</p>
+</div>
+
+<p>About twenty species are known, the distribution of which nearly
+coincides with <i>Dules</i>, but as some of the species are more or
+less marine, the genus is spread over the whole area of the tropical
+Indo-Pacific. Other species, especially those of Australian rivers, are
+entirely limited to fresh water. <i>Th. theraps</i>, <i>Th. servus</i>,
+and <i>Th. cuvieri</i> belong to the most common fishes of that area,
+extending from the east coast of Africa to Polynesia. They are readily
+recognised by the blackish longitudinal bands with which the body
+is ornamented. All the species are of small size. <i>Helotes</i> is
+closely allied to this genus.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pristipoma.</span>—Body oblong, compressed, with ctenoid
+scales of moderate size. Cleft of the mouth horizontal, not very
+wide, with the jaws nearly equal in length anteriorly; a central
+pit below the chin; villiform teeth in the jaws without canines;
+palate toothless. One dorsal, with eleven to fourteen spines;
+anal with three. Vertical fins not scaly, or with scales along
+the base only. Præoperculum serrated. Branchiostegals, seven.</p>
+</div>
+
+  <div class="figcenter" id="fig155" style="max-width: 261px">
+     <img
+    class="p1"   
+    src="images/fig155.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 155.—Lower view of mandible of Pristipoma manadense.</p>
+  </div>
+
+<p>About forty species are known, all from the sea. They are extremely
+common between the tropics, some of the<span class="pagenum" id="Page_386">[386]</span> species extending into the
+neighbouring sub-tropical parts. They do not attain a large size, and
+generally have a plain coloration. <i>Conodon</i> is an allied genus.</p>
+
+  <div class="figcenter" id="fig156" style="max-width: 332px">
+     <img
+    class="p1"   
+    src="images/fig156.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 156.—Hæmulon brevirostrum.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hæmulon.</span>—Body oblong, compressed, with ctenoid scales
+of moderate size. Cleft of the mouth horizontal, generally wide,
+with the jaws equal in length anteriorly; a central pit below
+the chin; villiform teeth in the jaws, without canines; palate
+toothless. One dorsal, with twelve or thirteen spines; anal with
+three; the soft portions of the vertical fins scaly to their
+margins. Præoperculum serrated. Branchiostegals, seven.</p>
+</div>
+
+<p>Marine; sixteen species are known from the coasts of Tropical America;
+they are of rather small size. The species figured occurs on both sides
+of Central America. <i>Hapalogenys</i> is an allied genus.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Diagramma.</span>—Body oblong, compressed, covered with
+rather small ctenoid scales. Upper profile of the head
+parabolic; cleft of the mouth small, horizontal; from four to
+six pores under the<span class="pagenum" id="Page_387">[387]</span> mandible, but without central pit. Teeth
+villiform, without canines; palate toothless. One dorsal fin,
+with from nine to fourteen spines; anal with three. Vertical
+fins not scaly. Præoperculum serrated; infraorbital not armed.
+Branchiostegals, six or seven.</p>
+</div>
+
+  <div class="figcenter" id="fig157" style="max-width: 704px">
+     <img
+    class="p1"   
+    src="images/fig157.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 157.—Diagramma orientale, from the Indo-Pacific.</p>
+  </div>
+
+<p>Forty species are known, which, with very few exceptions, belong to
+the tropical parts of the Indo-Pacific. Some attain to a size not very
+common among Sea-Perches, viz. to a length of from three to four feet.
+Many are agreeably coloured with black bands or spots. All appear to be
+esteemed as food. <i>Hyperoglyphe</i> from Australia is allied to this
+genus.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lobotes.</span>—Body rather elevated, compressed, with
+ctenoid scales of moderate size. Eye rather small. Snout
+obtuse, with oblique cleft of the mouth, and with the lower jaw
+longest. Teeth villiform, without canines; palate toothless. One
+dorsal fin with twelve spines; anal with three. Præoperculum
+denticulated. Branchiostegals, six.</p>
+</div>
+
+<p>A remarkable fish (<i>L. auctorum</i>) on account of its extraordinary
+range. Common in many localities, scarcer in others, it occurs in the
+East Indies, and on all the Atlantic coasts of tropical and temperate
+America. Döderlein found it on the coast of Sicily in 1875. It lives in
+salt and brackish water, and is known to attain to a length of two feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Histiopterus.</span>—Body rather elevated, strongly
+compressed, with very small scales. Snout much produced, the
+anterior profile of the head being concave. Mouth small,
+at the end of the snout. Teeth villiform, without canines;
+palate toothless. Some of the spines and rays of the vertical
+and pectoral fins very long. One dorsal, with about ten
+spines; anal with three. Præopercular margin partly serrated.
+Branchiostegals, six.</p>
+</div>
+
+<p>Marine. Four species are known from Japan and South Australia. The
+species figured attains to a length of 20<span class="pagenum" id="Page_388">[388]</span> inches, and is esteemed as
+food. It is known at Melbourne by the names of “Boar Fish” or “Bastard
+Dorey.”</p>
+
+  <div class="figcenter" id="fig158" style="max-width: 474px">
+     <img
+    class="p1"   
+    src="images/fig158.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 158.—Histiopterus recurvirostris.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gerres.</span>—Body oblong, or rather elevated, covered with
+scales of moderate size, which are either entirely smooth or
+minutely ciliated. Mouth very protractile, and descending when
+thrust out. Eye rather large. No canine teeth; dentition feeble,
+and palate toothless. The two divisions of the dorsal fin are
+nearly separated by a deep incision. Formula of the vertical
+fins—D. 9/10 A. 2·3/7·9. Caudal fin forked. Præoperculum
+generally without denticulation. Lower pharyngeal bones
+coalescent.</p>
+</div>
+
+  <div class="figcenter" id="fig159" style="max-width: 664px">
+     <img
+    class="p1"   
+    src="images/fig159.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 159.—Gerres altispinis, from the mouth of the Ganges.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_389">[389]</span></p>
+
+<p>More than thirty species are known of this genus, which bear so close a
+resemblance to one another that their distinction is rather difficult.
+They live in the seas between the Tropics, and some, perhaps all, of
+the species enter fresh water. Very rarely they exceed a length of ten
+inches; nearly all have a plain silvery coloration. The coalescence
+of their lower pharyngeals renders their systematic position rather
+uncertain, and, indeed, some Ichthyologists have referred them to the
+Pharyngognaths.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scolopsis.</span>—Body oblong, covered with scales finely
+serrated and of moderate size. Jaws nearly equal in length
+anteriorly; cleft of the mouth horizontal. Teeth villiform,
+without canines; palate toothless. One dorsal fin. Formula
+of the vertical fins: D. 10/9 A. 3/7. Caudal fin forked.
+Præoperculum distinctly denticulated; infraorbital ring with a
+spine directed backwards. Branchiostegals, five.</p>
+</div>
+
+  <div class="figcenter" id="fig160" style="max-width: 290px">
+     <img
+    class="p1"   
+    src="images/fig160.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 160.—Infraorbital spine of Scolopsis monogramma.</p>
+  </div>
+
+<p>Marine, and of small size. Twenty-five species are known from the
+tropical parts of the Indo-Pacific. <i>Heterognathodon</i> is an allied
+genus, but without the infraorbital spine.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Dentex.</span>—Body oblong, covered with ctenoid scales of
+moderate size. Cleft of the mouth nearly horizontal, with the
+jaws equal in length anteriorly. Canine teeth in both jaws;
+palate toothless. One dorsal fin. Formula of the vertical fins:
+D. 10·13/10·12 A. 3/8·9. Caudal fin forked. Præoperculum without
+serrature; præorbital unarmed and broad, there being a wide
+space between the eye and the cleft of the mouth. Cheek covered
+by more than three series of scales. Branchiostegals, six.</p>
+</div>
+
+<p>Marine Fishes, rather locally distributed in the Mediterranean, on the
+south coast of Africa, in the Red Sea, East Indian Archipelago, and
+on the coasts of China and Japan. About fourteen species are known,
+some of which attain a<span class="pagenum" id="Page_390">[390]</span> weight of 30 lbs. and more. They form a not
+unimportant article of food where they are found in any number, as on
+the Cape of Good Hope. The species found in the Mediterranean (<i>D.
+vulgaris</i>) wanders sometimes to the south coast of England, and is
+one of the larger species. The coloration of these fishes is rather
+uniform, silvery, or pink, or greenish. <i>Symphorus</i> is an allied
+genus from the Indo-Pacific.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Synagris.</span>—Body rather elongate, covered with ciliated
+scales of moderate size. Cleft of the mouth horizontal, with
+the jaws equal in length anteriorly. One continuous dorsal,
+with feeble spines; dorsal 10/9, anal 3/7. Caudal deeply
+forked. Teeth villiform, with canines at least in the upper
+jaw. Infraorbital not armed; præoperculum without, or with a
+very indistinct serrature. Cheek with three series of scales.
+Branchiostegals six.</p>
+</div>
+
+<p>Marine fishes of small size; about twenty species are known
+from the tropical parts of the Indo-Pacific. <i>Pentapus</i>,
+<i>Chætopterus</i>, and <i>Aphareus</i> are allied genera from the same
+area.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Maena.</span>—Body oblong, compressed, covered with
+ciliated scales of moderate size. Mouth very protractile, the
+intermaxillary pedicles extending backwards to the occiput.
+Teeth villiform; minute teeth on the vomer. One dorsal,
+scaleless, with feeble spines. D. 11/11, A. 3/9. Caudal fin
+forked. Præoperculum without serrature. Branchiostegals six.</p>
+</div>
+
+<p>Small fishes from the Mediterranean, known to the ancients; valueless
+as food. Three species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Smaris.</span>—Body oblong or cylindrical, covered with
+rather small ciliated scales. Mouth very protractile, the
+intermaxillary pedicles extending backwards to the occiput.
+Teeth villiform. Palate toothless. One dorsal, scaleless, with
+eleven or more very feeble spines; anal with three. Caudal fin
+forked. Præoperculum without serrature. Branchiostegals six.</p>
+</div>
+
+<p>Small fishes from the Mediterranean. Six species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cæsio.</span>—Body oblong, covered with ciliated scales of
+moderate size. Cleft of the mouth more or less oblique, with the
+jaws<span class="pagenum" id="Page_391">[391]</span> equal in length anteriorly, or with the lower somewhat
+projecting. Teeth villiform; palate generally toothless. One
+dorsal, with from nine to thirteen very feeble spines, with the
+anterior part highest, and the posterior covered with minute
+scales. Caudal fin deeply forked. Præoperculum without, or with
+minute, serrature.</p>
+</div>
+
+<p>Small fishes from the Indo-Pacific. Twelve species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Erythrichthys.</span>—Body elongate, covered with small
+ciliated scales. Mouth very protractile, the pedicles of the
+intermaxillary extending to the occiput. Dentition quite
+rudimentary or entirely absent Two dorsal fins connected by
+a series of very feeble spines; also the anterior spines are
+feeble. Præoperculum not serrated.</p>
+</div>
+
+  <div class="figcenter" id="fig161" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig161.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 161.—Erythrichthys nitidus.</p>
+  </div>
+
+  <div class="figcenter" id="fig162" style="max-width: 292px">
+     <img
+    class="p1"   
+    src="images/fig162.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 162.—Enlarged scale.</p>
+  </div>
+
+  <div class="figcenter" id="fig163" style="max-width: 366px">
+     <img
+    class="p1"   
+    src="images/fig163.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 163.—Protractile mouth.</p>
+  </div>
+
+<p>Small fishes from various tropical and temperate seas. Four species:
+the species figured occurs, but is not common,<span class="pagenum" id="Page_392">[392]</span> on the coasts of
+Western Austria, Tasmania, and New Zealand.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Oligorus.</span>—Body oblong, covered with small scales.
+Cleft of the mouth rather oblique, the lower jaw being the
+longer. Teeth villiform, without canines; teeth on the vomer
+and palatine bones. One dorsal, with eleven spines; anal with
+three; caudal fin rounded. Præoperculum with a single smooth or
+obtusely denticulated margin.</p>
+</div>
+
+<p>To this genus belong two fishes well known on account of the excellent
+flavour of their flesh. The first (<i>O. macquariensis</i>) is called
+by the colonists “Murray-Cod,” being plentiful in the Murray River
+and other rivers of South Australia. It attains to a length of more
+than three feet, and to a weight of nearly 100 lbs. The second (<i>O.
+gigas</i>) is found in the sea, on the coast of New Zealand, and called
+by the Maoris and colonists “Hapuku.” Its average weight is about 45
+lbs., but occasionally large specimens of more than a hundredweight
+are caught. At certain localities it is so plentiful that it may form
+an important article of trade. Dr. Hector, who has had opportunity of
+examining it in a fresh state, has pointed out anatomical differences
+from the Murray-Cod, from which it appears that it would be better
+placed in a distinct genus.</p>
+
+  <div class="figcenter" id="fig164" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig164.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 164.—The Murray-Cod, <i>Oligorus macquariensis</i>.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Grystes.</span>—Body oblong, covered with scales of moderate
+size. All the teeth villiform, without canines; teeth on the
+vomer and palatine bones. One dorsal fin with ten spines; anal
+with three; caudal fin rounded. Præoperculum with a single
+smooth margin.</p>
+</div>
+
+<p><span class="pagenum" id="Page_393">[393]</span></p>
+
+<p>One species, from the fresh waters of the United States (<i>G.
+salmonoides</i>), attains to a length of more than two feet. It is
+known by the name of “Growler,” and eaten.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Arripis.</span>—Body oblong, covered with scales of moderate
+size. All the teeth villiform, without canines; teeth on the
+vomer and palatine bones. One dorsal fin, with nine slender
+spines; anal with three. Præoperculum denticulated.</p>
+</div>
+
+  <div class="figcenter" id="fig165" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig165.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 165.—<i>Arripis salar</i>, South Australia.</p>
+  </div>
+
+<p>Three species are known, from the coasts of Southern Australia and New
+Zealand. They are named by the colonists Salmon or Trout, from their
+elegant form and lively habits, and from the sport they afford to the
+angler. Their usual size is from 1 to 3 lbs., but specimens of double
+that weight are taken. The smaller specimens are the more delicate and
+better flavoured. When not fresh, they are liable to assume poisonous
+properties; and cases of poisoning are not unfrequently caused by them.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Huro.</span>—Body oblong, compressed, covered with scales
+of moderate size. All the teeth villiform; bones of the head
+without serrature. Mouth rather oblique, with the lower jaw
+projecting. Two dorsal fins, the first with six spines.</p>
+</div>
+
+<p>The “Black Bass” of Lake Huron (<i>Huro nigricans</i>).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ambassis.</span>—Body short, strongly compressed, covered
+with large thin deciduous scales. Mouth oblique, with the lower
+jaw longest; teeth villiform, without conspicuously larger
+canines; teeth on the vomer and palatine bones. Two dorsal fins,
+the first with seven, the anal with three spines; a horizontal
+spine<span class="pagenum" id="Page_394">[394]</span> pointing forwards in front of the dorsal fin. The lower
+limb of the præoperculum with a double serrated margin.</p>
+</div>
+
+<p>This genus comprises the smallest of all Percoids, some of the species
+not much exceeding one inch in length. They are most abundant on the
+coasts of the tropical Indo-Pacific, and in the fresh waters belonging
+to that area. The species are numerous (some thirty having been
+described), and very difficult to distinguish. Their coloration is very
+plain, a silvery hue prevailing over the whole fish.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Apogon.</span>—Body rather short, covered with large
+deciduous scales. Mouth oblique, with the lower jaw longest;
+teeth villiform, without canines; teeth on the vomer and
+palatine bones. Two dorsal fins, the first with six or seven,
+the anal with two spines. Præoperculum with a double edge on the
+margin, one or both edges being serrated. Seven branchiostegals.</p>
+</div>
+
+  <div class="figcenter" id="fig166" style="max-width: 633px">
+     <img
+    class="p1"   
+    src="images/fig166.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 166.—Apogon frenatus.</p>
+  </div>
+
+<p>Although of similarly small size, the fishes of this genus represent a
+more highly developed form of the Percoid type than <i>Ambassis</i>.
+Their distribution coincides very much with that of <i>Ambassis</i>,
+but they are chiefly marine, comparatively few of the species entering
+fresh water. They belong to the kind of fishes which, from their habit,
+are termed “Coral Fishes,” being found in greatest abundance on, or
+in the<span class="pagenum" id="Page_395">[395]</span> neighbourhood of, coral reefs, in company with Chætodonts,
+Pomacentridæ, and others. Their colours also are ornamental and highly
+diversified, as is generally the case in coral fishes, the majority of
+the species showing transverse or longitudinal bands or large spots,
+and numerous other smaller markings which, in the dead fish, soon
+disappear. Nearly one hundred species have been described, of which
+a few only occur in the Atlantic, one extending northwards into the
+Mediterranean.</p>
+
+<p><i>Chilodipterus</i>, <i>Acropoma</i>, and <i>Scombrops</i> are allied
+genera, but with canine teeth in one or both jaws.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pomatomus.</span>—Body oblong, covered with scales of
+moderate size. Eye very large. All the teeth villiform, without
+canines; teeth on the vomer and palatine bones. Two dorsal fins,
+the first with seven, the anal with two spines. No serration on
+any of the bones of the head. Branchiostegals seven.</p>
+</div>
+
+<p>One species only is known, <i>P. telescopium</i>, which grows to a
+length of nearly two feet. It is not uncommon in the Mediterranean and
+neighbouring parts of the Atlantic, but only occasionally caught, as it
+lives habitually at a greater depth than any other Percoid as far as is
+known at present, probably at depths from 80 to 200 fathoms; a habit
+sufficiently indicated by its exceedingly large eye.</p>
+
+<p><span class="smcap">Priacanthus.</span>—Body short, compressed, covered with small rough
+scales, which extend also over the short snout. Lower jaw and chin
+prominent. Eye large. All the teeth villiform, without canines; teeth
+on the vomer and palatine bones. One dorsal fin with ten spines, anal
+with three. Præoperculum serrated, with a more or less prominent, flat,
+triangular spine at the angle.</p>
+
+<p>A very natural genus, easily recognised, and without direct relation to
+the other Percoid genera. The species, of which seventeen are known,
+are spread over nearly all the tropical seas, and belong to the more
+common fishes. They<span class="pagenum" id="Page_396">[396]</span> scarcely exceed a length of twelve inches, and are
+very uniformly coloured, red, pink, and silvery prevailing.</p>
+
+<hr class="tb">
+
+<p class="p-left">The following three genera form a group by themselves,
+which, however, is defined rather by its geographical limits and
+similarity of general appearance than by distinctive anatomical
+characters. The species are abundant in the fresh waters of the United
+States, and well known by the name of “Sun Fishes.” They rarely exceed
+a length of six inches, and are not used as food. The number of species
+is uncertain.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centrarchus.</span>—Body short, compressed, with scales of
+moderate size. All the teeth villiform, without canines; teeth
+on the vomer, palatines, and on the tongue. One dorsal fin; anal
+generally with more than three spines. Præoperculum without
+serrature; operculum not lobed.</p>
+
+<p><span class="smcap">Bryttus.</span>—Body short, compressed, with scales of
+moderate size. All the teeth villiform, without canines; teeth
+on the vomer and palatine bones. One dorsal fin with nine
+or ten, anal with three spines. Præoperculum not serrated;
+operculum with a rounded membranaceous coloured lobe behind.</p>
+
+<p><span class="smcap">Pomotis.</span>—Body short, compressed, with scales of
+moderate length. All the teeth villiform, without canines; teeth
+on the vomer, but none on the palatine bones. One dorsal, with
+from nine to eleven spines, anal with three. Præoperculum entire
+or minutely serrated; operculum with a rounded membranaceous
+coloured lobe behind.</p>
+</div>
+
+<hr class="tb">
+
+<p class="p-left">A <span class="smcap">North American</span> Freshwater genus,
+<i>Aphredoderus</i>, occupies a perfectly isolated position in the
+system, and is evidently the type of a distinct family. It resembles
+the “Sun-fishes” of the same country with regard to the structure of
+the vertical fins, but has the vent situated in front of the ventrals,
+which are composed of more than five soft rays. The body is oblong,
+compressed, covered with ctenoid scales. The dorsal fin is single, and
+has three spines in front. Infraorbital and præoperculum with spinous
+teeth. Villiform teeth in the<span class="pagenum" id="Page_397">[397]</span> jaws, on the vomer and palatine bones.
+<i>A. sayanus</i> from the southern streams and fresh waters of the
+Atlantic States.</p>
+
+<p class="p-left">To complete the list of Percoid genera, we have to
+mention the following:—<i>Siniperca</i>, <i>Etelis</i>, <i>Niphon</i>,
+<i>Aprion</i>, <i>Apsilus</i>, <i>Pentaceros</i>, <i>Velifer</i>,
+<i>Datnioides</i>, <i>Percilia</i>, <i>Lanioperca</i>.</p>
+
+
+<h6 class="smcap">Second Family—Squamipinnes.</h6>
+
+<p><i>Body compressed and elevated, covered with scales, either finely
+ctenoid or smooth. Lateral line continuous, not continued over the
+caudal fin. Mouth in front of the snout, generally small, with lateral
+cleft. Eye lateral, of moderate size. Six or seven branchiostegals.
+Teeth villiform or setiform, in bands, without canines or incisors.
+Dorsal fin consisting of a spinous and soft portion of nearly equal
+development; anal with three or four spines, similarly developed as
+the soft dorsal, both being many-rayed. The vertical fins more or less
+densely covered with small scales. The lower rays of the pectoral fin
+branched, not enlarged; ventrals thoracic, with one spine and five soft
+rays. Stomach coecal.</i></p>
+
+<p>The typical forms of this family are readily recognised by the form
+of their body, and by a peculiarity from which they derive their name
+<i>Squamipinnes</i>; the soft, and frequently also the spinous part
+of their dorsal and anal fins are so thickly covered with scales
+that the boundary between fins and body is entirely obliterated. The
+majority are inhabitants of the tropical seas, and abound chiefly
+in the neighbourhood of coral-reefs. The beauty and singularity of
+distribution of the colours of some of the genera, as <i>Chætodon</i>,
+<i>Heniochus</i>, <i>Holacanthus</i>, is scarcely surpassed by any
+other group of fishes. They remain within small dimensions, and
+comparatively few are used as food. They are carnivorous, feeding on
+small invertebrates. Only a few species enter brackish water.</p>
+
+<p><span class="pagenum" id="Page_398">[398]</span></p>
+
+<p>Extinct representatives of this family are not scarce at Monte
+Bolca and in other tertiary formations. All, at least those
+admitting of definite determination, belong to existing genera,
+viz. <i>Holacanthus</i>, <i>Pomacanthus</i>, <i>Ephippium</i>,
+<i>Scatophagus</i>. Very singular is the occurrence of <i>Toxotes</i>
+in the Monte Bolca strata.</p>
+
+<p>The following genera have no teeth on the palate:—</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chætodon.</span>—One dorsal fin, without any notch in
+its upper margin, and with the soft and spinous portions
+similarly developed; none of the spines elongate. Snout short
+or of moderate length. Præoperculum without, or with a fine,
+serration, and without spine at the angle. Scales generally
+large or of moderate size.</p>
+</div>
+
+  <div class="figcenter" id="fig167" style="max-width: 646px">
+     <img
+    class="p1"   
+    src="images/fig167.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 167.—Chætodon ephippium.</p>
+  </div>
+
+<p>Seventy species are known from the tropical parts of the Atlantic and
+Indo-Pacific, nearly all being beautifully ornamented with bands or
+spots. Of the ornamental markings a dark or bicoloured band, passing
+through the eye and ascending towards the back, is very generally
+found in these fishes; it frequently occurs again in other marine
+Acanthopterygians, in which it is not rarely a sign of the immature
+condition of the individual. The Chætodonts are most numerous in the
+neighbourhood of the coral-reefs of the Indo-Pacific, the species
+figured (<i>C. ephippium</i>) being as common<span class="pagenum" id="Page_399">[399]</span> in the East Indian
+Archipelago as in Polynesia, like many others of its congeners.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chelmo</span> differs from <i>Chætodon</i> only in having the
+snout produced into a more or less long tube.</p>
+</div>
+
+  <div class="figcenter" id="fig168" style="max-width: 523px">
+     <img
+    class="p1"   
+    src="images/fig168.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 168.—Chelmo marginalis, from the coast of
+Australia.</p>
+  </div>
+
+<p>Only four species are known, locally distributed in the tropical seas.
+<i>Ch. rostratus</i>, the oldest species known, is said to have the
+instinct of throwing a drop of water from its bill so as to light
+upon any insect resting on a leaf, and thus make it fall, that it may
+instantly dart upon it. This statement is erroneous, and probably rests
+upon the mistaken notion that the long bill is especially adapted for
+this manœuvre, which, indeed, is practised by another fish of this
+family (<i>Toxotes</i>). The long slender bill of Chelmo (which is a
+true saltwater fish) rather enables it to draw from holes and crevices
+animals which otherwise could not be reached by it.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Heniochus.</span>—One dorsal, with from eleven to thirteen
+spines, the fourth of which is more or less elongate and
+filiform. Snout<span class="pagenum" id="Page_400">[400]</span> rather short or of moderate length.
+Præoperculum without spine. Scales of moderate size.</p>
+</div>
+
+<p>Four species are known from the tropical Indo-Pacific. <i>H.
+macrolepidotus</i> is one of the most common fishes of that area; the
+species figured (<i>H. varius</i>) retains in a conspicuous manner
+horn-like protuberances on bones of the head, with which the young of
+all the species of this genus seem to be armed.</p>
+
+  <div class="figcenter" id="fig169" style="max-width: 375px">
+     <img
+    class="p1"   
+    src="images/fig169.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 169.—Heniochus varius.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Holacanthus.</span>—Præoperculum with a strong spine at the
+angle. One dorsal, with from twelve to fifteen spines. Scales of
+moderate or small size.</p>
+</div>
+
+<p>Forty species are known, which, in their geographical distribution
+accompany, and are quite analogous to, the Chætodonts. One of the most
+common and most beautiful is called “Emperor of Japan” by the Dutch,
+which name has been adopted by Bloch for its specific designation,
+<i>Holacanthus imperator</i>. Its body is blue, longitudinally
+traversed<span class="pagenum" id="Page_401">[401]</span> by about thirty yellow bands; the ocular band, and the
+side behind the head, are black, edged with yellow; the caudal fin
+is yellow. It is a large species of this genus, sometimes attaining
+a length of 15 inches, and as an article of food is one of the most
+esteemed of all the Indian species. With regard to beauty of colours
+it is surpassed by another allied species, <i>H. diacanthus</i>, which
+likewise ranges from the east coast of Africa to Polynesia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pomacanthus</span> differs from <i>Holacanthus</i> in having
+from eight to ten spines only in the dorsal fin.</p>
+</div>
+
+<p>The single species (<i>P. paru</i>) on which this genus is founded is
+one of the most common fishes of the West Indies, and offers one of
+the most remarkable instances of variation of colour within the limits
+of the same species: some specimens being ornamented with more or less
+distinct yellowish cross-bands, others with yellow crescent-shaped
+spots; in others black spots predominate.</p>
+
+  <div class="figcenter" id="fig170" style="max-width: 508px">
+     <img
+    class="p1"   
+    src="images/fig170.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 170.—Scatophagus multifasciatus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scatophagus.</span>—Two dorsal fins, united at the base, the
+first with ten or eleven spines; only the second is scaly. A
+recumbent spine before the dorsal, pointing forwards. Anal with
+four<span class="pagenum" id="Page_402">[402]</span> spines. Snout rather short. Præoperculum without spine.
+Scales very small.</p>
+</div>
+
+<p>Four species are known, from the Indian Ocean, of which <i>S. argus</i>
+is the most generally known, in fact, one of the most common Indian
+shore-fishes. It freely enters large rivers, and is said not to be
+particular in the selection of its food. The species figured (<i>S.
+multifasciatus</i>) represents <i>S. argus</i> on the coasts of
+Australia.</p>
+
+  <div class="figcenter" id="fig171" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig171.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 171.—Bony enlargement of cranial bones of
+Ephippus. <i>a</i>, Enlargement of the frontal, and <i>b</i>, of the
+supraoccipital bones; <i>c</i>, interorbital septum; <i>d</i>, basis
+cranii. ⅓ nat. size.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ephippus.</span>—Snout short, with the upper profile
+parabolic. Dorsal fin deeply emarginate between the spinous and
+soft portions, the former with nine spines, the third of which
+is rather elongate, and flexible; spinous portion not scaly;
+anal spines three. Pectoral fin short. Præoperculum without
+spine. Scales of moderate size, or rather small.</p>
+</div>
+
+<p>Two or three species are known from the warmer parts of the Atlantic
+and Indian Oceans. The Atlantic species (<i>E. faber</i>) shows the
+remarkable peculiarity that in old specimens (12 and more inches long)
+the occipital crest, and sometimes some of the anterior neural and
+hæmal spines are enormously enlarged into a globular bony mass. This
+can hardly be regarded as a pathological change of the bone, as it has
+been found in all old specimens, without exception.</p>
+
+<p><i>Drepane</i> is allied to <i>Ephippus</i>, but has very long
+falciform pectoral fins. The single species <i>D. punctata</i>
+is common in the Indian Ocean and on the coasts of Australia.
+<i>Hypsinotus</i>, from Japan, appears to inhabit a greater depth than
+the other Squamipinnes.</p>
+
+<p><i>Scorpis</i> and <i>Atypichthys</i> are genera distinguished from
+the<span class="pagenum" id="Page_403">[403]</span> preceding by the presence of vomerine teeth. They belong to the
+coast-fauna of Australia, New Zealand, and Chili.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Toxotes.</span>—Body short, compressed, covered with scales
+of moderate size. Snout pointed, with a wide lateral mouth
+and projecting lower jaw. One dorsal, with five strong spines
+situated on the posterior part of the back; the soft portion
+and the anal fin scaly, the latter with three spines. Villiform
+teeth in the jaws, on the vomer and palatine bones. Scales of
+moderate size, cycloid.</p>
+</div>
+
+  <div class="figcenter" id="fig172" style="max-width: 697px">
+     <img
+    class="p1"   
+    src="images/fig172.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 172.—Toxotes jaculator.</p>
+  </div>
+
+<p>Two species are known from the East Indies, one (<i>T. jaculator</i>),
+which is the more common, ranging to the north coast of Australia. It
+has received its name from its habit of throwing a drop of water at an
+insect which it perceives close to the surface, in order to make it
+fall into it. The Malays, who call it “Ikan sumpit,” keep it in a bowl,
+in order to witness this singular habit, which it continues even in
+captivity.</p>
+
+
+<h6 class="smcap">Third Family—Mullidæ.</h6>
+
+<p><i>Body rather low and slightly compressed, covered with large thin
+scales, without or with an extremely fine serrature. Two long erectile
+barbels are suspended from the hyoid, and are received between the rami
+of the lower jaw and opercles. Lateral line continuous. Mouth in front
+of the snout, with the cleft<span class="pagenum" id="Page_404">[404]</span> lateral and rather short; teeth very
+feeble. Eye lateral, of moderate size. Two short dorsal fins remote
+from each other, the first with feeble spines; anal similar to the
+second dorsal. Ventrals with one spine and five rays. Pectorals short.
+Branchiostegals four; stomach siphonal.</i></p>
+
+<p>The “Red Mullets” form a very natural family, which, on account of
+slight modifications of the dentition, has been divided into several
+sub-genera—<i>Upeneoides</i>, <i>Upeneichthys</i>, <i>Mullus</i>,
+<i>Mulloides</i>, and <i>Upeneus</i>. They are marine fishes, but many
+species enter brackish water to feed on the animalcules abounding in
+the flora of brack-water. About forty different species are known
+chiefly from tropical seas, the European species (<i>M. barbatus</i>,
+see p. 43, Fig. <a href="#fig7">7</a>), extending far northwards into the temperate zone.
+None attain to a large size, specimens of from two to three lbs. being
+not common, but all are highly esteemed as food.</p>
+
+<p>The most celebrated is the European species (of which there is one
+only, <i>M. surmuletus</i> being probably the female). The ancient
+Romans called it <i>Mullus</i>, the Greeks τριγλη. The Romans priced it
+above any other fish; they sought for large specimens far and wide, and
+paid ruinous prices for them.</p>
+
+  <div class="poetry-container">
+   <div class="poetry">
+      <div class="stanza">
+        <div class="i4h">“Mullus tibi quatuor emptus</div>
+        <div>Librarum, cœnæ pompa caputque fuit,</div>
+        <div>Exclamare libet, non est hic improbe, non est</div>
+        <div>Piscis: homo est; hominem, Calliodore, voras.”</div>
+        <div class="right"><span class="smcap">Martial</span>, x. 31.</div>
+      </div>
+    </div>
+  </div>
+
+<p>Then, as nowadays, it was considered essential for the enjoyment of
+this delicacy that the fish should exhibit the red colour of its
+integuments. The Romans brought it, for that purpose, living into the
+banqueting room, and allowed it to die in the hands of the guests, the
+red colour appearing in all its brilliancy during the death struggle of
+the fish. The fishermen of our times attain the same object by scaling
+the<span class="pagenum" id="Page_405">[405]</span> fish immediately after its capture, thus causing a permanent
+contraction of the chromatophors containing the red pigment (see p.
+183).</p>
+
+
+<h6 class="smcap">Fourth Family—Sparidæ.</h6>
+
+<p><i>Body compressed, oblong, covered with scales, the serrature of which
+is very minute, and sometimes altogether absent. Mouth in front of the
+snout, with the cleft lateral. Eye lateral, of moderate size. Either
+cutting teeth in front of the jaws, or molar teeth on the side; palate
+generally toothless. One dorsal fin, formed by a spinous and soft
+portion of nearly equal development. Anal fin with three spines. The
+lower rays of the pectoral fin are generally branched, but in one genus
+simple. Ventrals thoracic, with one spine and five rays.</i></p>
+
+<p>The “Sea-breams” are recognised chiefly by their dentition, which is
+more specialised than in the preceding families, and by which the
+groups, into which this family has been divided, are characterised.
+They are inhabitants of the shores of all the tropical and temperate
+seas. Their coloration is very plain. They do not attain to a large
+size, but the majority are used as food.</p>
+
+<p>The extinct forms found hitherto are rather numerous; the oldest come
+from the cretaceous formation of Mount Lebanon; some belong to living
+genera, as <i>Sargus</i>, <i>Pagellus</i>; of others from Eocene and
+Miocene formations no living representative is known—<i>Sparnodus</i>,
+<i>Sargodon</i>, <i>Capitodus</i>, <i>Soricidens</i>, <i>Asima</i>.</p>
+
+<p><i>First Group—Cantharina.</i>—More or less broad cutting, sometimes
+lobate, teeth in front of the jaws; no molars or vomerine teeth;
+the lower pectoral rays are branched. Partly herbivorous, partly
+carnivorous. The genera belonging to this group are:—<i>Cantharus</i>
+from the European and South African coasts, of which one species
+(<i>C. lineatus</i>), is common on the coasts of Great Britain,
+and locally known by the<span class="pagenum" id="Page_406">[406]</span> names “Old Wife,” “Black Sea-bream;”
+<i>Box</i>, <i>Scatharus</i>, and <i>Oblata</i> from the Mediterranean
+and neighbouring parts of the Atlantic; <i>Crenidens</i> and
+<i>Tripterodon</i> from the Indian Ocean; <i>Pachymetopon</i>,
+<i>Dipterodon</i>, and <i>Gymnocrotaphus</i> from the Cape of Good
+Hope; <i>Girella</i> and <i>Tephræops</i> from Chinese, Japanese, and
+Australian Seas; <i>Doydixodon</i> from the Galapagos Islands and the
+coasts of Peru.</p>
+
+  <div class="figcenter" id="fig173" style="max-width: 722px">
+     <img
+    class="p1"   
+    src="images/fig173.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 173.—Tephræops richardsonii, from King George’s Sound.</p>
+  </div>
+
+<p><i>Second Group—Haplodactylina.</i>—In both jaws flat and generally
+tricuspid teeth; no molars; vomerine teeth. The lower pectoral rays
+simple, not branched. Vegetable feeders. Only one genus is known,
+<i>Haplodactylus</i>, from the temperate zone of the Southern Pacific.</p>
+
+<p><i>Third Group—Sargina.</i>—Jaws with a single series of incisors
+in front, and with several series of rounded molars on the side. One
+genus is known, <i>Sargus</i>, which comprises twenty species; several
+of them occur in the Mediterranean and the neighbouring parts of the
+Atlantic, and are popularly called “Sargo,” “Sar,” “Saragu:” names
+derived from the word Sargus, by which name these fishes were well
+known to the ancient Greeks and Romans. One of the largest species is
+the “Sheep’s-head” (<i>Sargus ovis</i>), from the coasts of the United
+States, which attains to a weight of 15 lbs., and is highly esteemed on
+account of the excellency of its flesh. Singularly enough, this genus
+occurs also on the east coast of Africa, one of these East-African
+species being identical with<span class="pagenum" id="Page_407">[407]</span> <i>S. noct</i> from the Mediterranean.
+These fishes evidently feed on hard-shelled animals, which they crush
+with their molar teeth.</p>
+
+  <div class="figcenter" id="fig174" style="max-width: 559px">
+     <img
+    class="p1"   
+    src="images/fig174.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 174.—The Sheep’s-head, <i>Sargus ovis</i>, of
+North America.</p>
+  </div>
+
+  <div class="figcenter" id="fig175" style="max-width: 230px">
+     <img
+    class="p1"   
+    src="images/fig175.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 175.—Scale of Lethrinus.</p>
+  </div>
+
+<p><i>Fourth Group—Pagrina.</i>—Jaws with conical teeth in front and
+molar teeth on the sides. Feeding, as the preceding, on hard-shelled
+animals, like Mollusks and Crustaceans. This group is composed of
+several genera:—</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lethrinus.</span>—Cheeks scaleless. Body oblong, covered with
+scales of moderate size (L. lat. 45–50). Canine teeth in front;
+lateral teeth in a single series, broadly conical or molar-like.
+Formula of the fins: D. 10/9, A. 3/8.</p>
+</div>
+
+<p>More than twenty species are known, all of which, with one exception,
+occur in the tropical Indo-Pacific. The species, forming this
+exception, occurs, singularly enough, on the west coast of Africa,
+where more than one Indian genus<span class="pagenum" id="Page_408">[408]</span> reappears in isolated representative
+species. Some Lethrini attain to a length of three feet.</p>
+
+<p><i>Sphærodon</i> is closely allied to <i>Lethrinus</i>, but has scales
+on the cheek. One species from the Indo-Pacific.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pagrus.</span>—Body oblong, compressed, with scales of
+moderate size. Several pairs of strong canine-like teeth in both
+jaws; molars arranged in two series. Cheeks scaly. The spines
+of the dorsal fin, eleven or twelve in number, are sometimes
+elongate, and can be received in a groove; anal spines three.</p>
+</div>
+
+<p>Thirteen species are known, chiefly distributed in the warmer parts
+of the temperate zones, and more scantily represented between the
+tropics. Several species (<i>P. vulgaris, P. auriga, P. bocagii</i>)
+occur in the Mediterranean and the neighbouring parts of the Atlantic;
+one (<i>P. argyrops</i>) is well known on the coasts of the United
+States under the names of “Scup,” “Porgy,” or “Mishcup,” and one of
+the most important food fishes, growing to a length of 18 inches and a
+weight of 4 lbs.; another (<i>P. unicolor</i>) is one of the best-known
+sea-fishes of Southern Australia and New Zealand, where it is called
+“Snapper;” it is considered very good eating, like all the other
+species of this genus, and attains, like some of them, a length of more
+than 3 feet and a weight exceeding 20 lbs.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pagellus.</span>—Body oblong, compressed, with scales of
+moderate size. Jaws without canines; molars on the sides
+arranged in several series. Cheeks scaly. The spines of the
+dorsal fin, from eleven to thirteen in number, can be received
+in a groove; anal spines three.</p>
+</div>
+
+<p>Seven species are known, the majority of which are European, as
+<i>P. erythrinus</i>, common in the Mediterranean, and not rare on
+the south coast of England, where it is generally termed “Becker;”
+<i>P. centrodontus</i>, the common “Sea-bream” of the English coasts,
+distinguished by a black spot on the origin of the lateral line; in the
+young, which are called “Chad” by Cornish and Devon fishermen, this
+spot is absent;<span class="pagenum" id="Page_409">[409]</span> <i>P. owenii</i>, the “Axillary or Spanish Sea-Bream,”
+likewise from the British coasts. <i>Pagellus lithognathus</i>, from
+the coasts of the Cape of Good Hope, attains to a length of four feet,
+and is one of the fishes which are dried for export and sale to whalers.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chrysophrys.</span>—Body oblong, compressed, with scales of
+moderate size. Jaws with four or six canine teeth in front, and
+with three or more series of rounded molars on each side. Cheeks
+scaly. The spines of the dorsal fin, eleven or twelve in number,
+can be received in a groove; anal spines three.</p>
+</div>
+
+<p>Some twenty species are known from tropical seas and the warmer parts
+of the temperate zones. Generally known is <i>Ch. aurata</i>, from
+the Mediterranean, occasionally found on the south coast of England,
+where it is named “Gilthead.” The French call it “Daurade,” no doubt
+from the Latin <i>Aurata</i>, a term applied to it by ancient authors.
+The Greeks named it Chrysophrys (<i>i.e.</i> golden eyebrow), in
+allusion to the brilliant spot of gold which it bears between its
+eyes. According to Columella, the Aurata was among the number of the
+fishes brought up by the Romans in their vivaria; and the inventor
+of those vivaria, one Sergius Orata, is supposed to have derived his
+surname from this fish. It is said to grow extremely fat in artificial
+ponds. Duhamel states that it stirs up the sand with the tail, so as
+to discover the shell-fish concealed in it. It is extremely fond of
+mussels, and its near presence is sometimes ascertained by the noise
+which it makes while breaking their shells with its teeth. Several
+species found on the Cape of Good Hope attain to as large a size as
+<i>Pagellus lithognathus</i>, and are preserved for sale like that
+species. <i>Chrysophrys hasta</i> is one of the most common species of
+the East Indian and Chinese coasts, and enters large rivers.</p>
+
+<p><i>Fifth Group—Pimelepterina.</i>—In both jaws a single anterior
+series of cutting teeth, implanted by a horizontal posterior process,
+behind which is a band of villiform teeth.<span class="pagenum" id="Page_410">[410]</span> Villiform teeth on the
+vomer, palatines and the tongue. Vertical fins densely covered with
+minute scales. Only one genus is known, <i>Pimelepterus</i>, with six
+species from tropical seas. These fishes are sometimes found at a great
+distance from the land.</p>
+
+
+<h6 class="smcap">Fifth Family—Hoplognathidæ.</h6>
+
+<p><i>Body compressed and elevated, covered with very small ctenoid
+scales. Lateral line continuous. The bones of the jaws have a sharp
+dentigerous edge, as in Scarus. The teeth, if at all conspicuous, being
+continuous with the bone, forming a more or less indistinct serrature;
+no teeth on the palate. The spinous portion of the dorsal fin is rather
+more developed than the soft; the spines strong; anal with three
+spines, similar to the soft dorsal. Ventrals thoracic, with one spine
+and five soft rays.</i></p>
+
+<p>One genus only is known, <i>Hoplognathus</i>, with four species from
+Australian, Japanese, and Peruvian coasts.</p>
+
+  <div class="figcenter" id="fig176" style="max-width: 303px">
+     <img
+    class="p1"   
+    src="images/fig176.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 176.—Teeth of Hoplognathus.</p>
+  </div>
+
+
+<h6 class="smcap">Sixth Family—Cirrhitidæ.</h6>
+
+<p><i>Body oblong, compressed, covered with cycloid scales; lateral
+line continuous. Mouth in front of the snout, with lateral cleft.
+Eye lateral, of moderate size. Cheeks without a bony stay for the
+præoperculum. Generally six, sometimes five or three branchiostegals.
+Dentition more or less complete, composed of small pointed teeth,
+sometimes with the addition of canines. One dorsal fin, formed by a
+spinous and soft portion, of nearly equal development. Anal with three
+spines, generally less developed than the soft dorsal. The lower rays
+of the pectoral fins simple and generally enlarged; ventrals thoracic,
+but remote from the root of the pectorals, with one spine and five
+rays.</i></p>
+
+<p><span class="pagenum" id="Page_411">[411]</span></p>
+
+<p>The fishes of this family may be readily recognised by their thickened,
+undivided lower pectoral rays, which in some are evidently auxiliary
+organs of locomotion, in others, probably, organs of touch. They
+differ from the following family, the Scorpænidæ, in lacking the
+bony connection between the infraorbital ring and the præoperculum.
+Two groups may be distinguished in this family, which, however,
+are connected by an intermediate genus (<i>Chironemus</i>). The
+first, distinguished by the presence of vomerine teeth, consists of
+<i>Cirrhites</i> and <i>Chorinemus</i>, small prettily coloured fishes.
+The former genus is peculiar to the Indo-Pacific, and consists of
+sixteen species; the second, with three species, seems to be confined
+to the coasts of Australia and New Zealand. The second group lacks the
+vomerine teeth, and comprises the following genera:—</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chilodactylus.</span>—One dorsal fin, with from sixteen to
+nineteen spines; anal fin of moderate length; caudal forked.
+One of the simple pectoral rays more or less prolonged, and
+projecting beyond the margin of the fin. Teeth in villiform
+bands; no canines. Præoperculum not serrated. Scales of moderate
+size. Air-bladder with many lobes.</p>
+</div>
+
+  <div class="figcenter" id="fig177" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig177.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 177.—<i>Chilodactylus macropterus</i>, from
+Australia.</p>
+  </div>
+
+<p>Seventeen species are known, chiefly from the temperate parts of the
+Southern Pacific, and also from the coasts of Japan and China. They
+belong to the most valuable food-fishes, as they grow to a considerable
+size (from five to<span class="pagenum" id="Page_412">[412]</span> twenty-five lbs.), and are easily caught in
+numbers. At the Cape of Good Hope they are very abundant, and preserved
+in large quantities for export.</p>
+
+<p><i>Mendosoma</i> from the coast of Chili, and <i>Nemadactylus</i> from
+Tasmania, are allied genera.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Latris.</span>—Dorsal fin deeply notched; the spinous portion
+with seventeen spines; anal fin many-rayed. None of the simple
+pectoral rays passes the margin of the fin. Teeth villiform; no
+canines. Præoperculum minutely serrated. Scales small.</p>
+</div>
+
+<p>Two species only are known from Tasmania and New Zealand, which belong
+to the most important food-fishes of the Southern Hemisphere. <i>Latris
+hecateia</i> or the “Trumpeter,” ranges from sixty to thirty lbs. in
+weight, and is considered by the colonists the best flavoured of any of
+the fishes of South Australia, Tasmania, and New Zealand, and consumed
+smoked as well as fresh. The second species, <i>Latris ciliaris</i>, is
+smaller, scarcely attaining a weight of twenty lbs., but more abundant;
+it is confined to the coast of New Zealand.</p>
+
+  <div class="figcenter" id="fig178" style="max-width: 486px">
+     <img
+    class="p1"   
+    src="images/fig178.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 178.—Skull of <i>Scorpæna percoides</i>;
+<i>so</i>, Suborbital ring; <i>pr</i>, Præoperculum; <i>st</i>, Bony
+stay, connecting the sub-orbital with the præoperculum.</p>
+  </div>
+
+
+<h6 class="smcap">Seventh Family—Scorpænidæ.</h6>
+
+<p><i>Body oblong, more or less compressed, covered with ordinary scales,
+or naked. Cleft of the mouth lateral or subvertical. Dentition feeble,
+consisting of villiform teeth; and generally without canines. Some
+bones of the head armed, especially the angle of the præoperculum,
+its armature receiving additional support by a bony stay, connecting
+it with the infraorbital ring. The spinous portion of the dorsal fin
+equally<span class="pagenum" id="Page_413">[413]</span> or more developed than the soft and than the anal. Ventrals
+thoracic, generally with one spine and five soft rays, sometimes
+rudimentary.</i></p>
+
+<p>This family consists of carnivorous marine fishes only; some
+resemble the Sea-Perches in form and habits, as <i>Sebastes</i>,
+<i>Scorpæna</i>, etc., whilst others live at the bottom of the sea,
+and possess in various degrees of development those skinny appendages
+resembling the fronds of seaweeds, by which they either attract
+other fishes, or by which they are enabled more effectually to hide
+themselves. Species provided with those appendages have generally a
+coloration resembling that of their surroundings, and varying with
+the change of locality. The habit of living on the bottom has also
+developed in many Scorpænoids separate pectoral rays, by means of which
+they move or feel. Some of the genera live at a considerable depth, but
+apparently not beyond 300 fathoms. Nearly all are distinguished by a
+powerful armature either of the head, or fin spines, or both; and in
+some the spines have been developed into poison organs.</p>
+
+<p>The only fossil representative known at present is a species of
+<i>Scorpæna</i> from the Eocene of Oran.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sebastes.</span>—Head and body compressed; crown of the head
+scaly to, or even beyond, the orbits; no transverse groove on
+the occiput. Body covered with scales of moderate or small size,
+and without skinny tentacles. Fin-rays not elongate; one dorsal,
+divided by a notch into a spinous and soft portion, with twelve
+or thirteen spines; the anal with three. No pectoral appendages.
+Villiform teeth in the jaws, on the vomer, and generally on the
+palatine bones. Vertebræ more than twenty-four.</p>
+</div>
+
+<p>About twenty species are known, principally from seas of the temperate
+zones, as from the coasts of Northern Europe (<i>S. norvegicus</i>,
+<i>S. viviparus</i>), of Japan, California, New Zealand, and Van
+Diemen’s Land. All seem to prefer deep water to the surface, and
+<i>Sebastes macrochir</i> has been obtained at a<span class="pagenum" id="Page_414">[414]</span> depth of 345 fathoms.
+In their general form they resemble the Sea-Perches, attain to a weight
+of from one to four lbs., and are generally esteemed as food.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scorpæna.</span>—Head large, slightly compressed, generally
+with a transverse naked depression on the occiput; bones of the
+head armed with spines, and generally with skinny tentacles.
+Scales of moderate size. Mouth large, oblique. Villiform teeth
+in the jaws, and at least on the vomer. One dorsal, 12–13/9, A.
+3/5. Pectoral fins without detached rays, large, rounded, with
+the lower rays simple and thickened. Air-bladder none. Vertebræ
+twenty-four.</p>
+</div>
+
+  <div class="figcenter" id="fig179" style="max-width: 584px">
+     <img
+    class="p1"   
+    src="images/fig179.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 179.—Head of Scorpæna percoides, from New Zealand.</p>
+  </div>
+
+  <div class="figcenter" id="fig180" style="max-width: 720px">
+     <img
+    class="p1"   
+    src="images/fig180.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 180.—Scorpæna bynoensis, from the coasts of
+Australia.</p>
+  </div>
+
+<p>About forty species are known from tropical and sub-tropical seas.
+They lead a sedentary life, lying hidden in the sand, or between rocks
+covered with seaweed, watching for their prey, which chiefly consists
+of small fishes. Their strong undivided pectoral rays aid them in
+burrowing in the<span class="pagenum" id="Page_415">[415]</span> sand, and in moving along the bottom. The type of
+their coloration is very much the same in all the species, viz. an
+irregular mottling of red, yellow, brown, and black colours, but the
+distribution of these colours varies exceedingly, not only in the same
+species but also in the same individuals. They do not attain to any
+considerable size, probably never exceeding a length of 18 inches.
+Their flesh is well flavoured. Wounds inflicted by their fin-spines are
+exceedingly painful, but not followed by serious consequences.</p>
+
+<p><i>Glyptauchen</i> and <i>Lioscorpius</i> are genera closely allied to
+<i>Scorpæna</i>, from Australian seas.</p>
+
+<p><i>Setarches</i> is also allied to the preceding genera, and provided
+with very large eyes, in accordance with the depth (215 fathoms) which
+the two species known at present inhabit; one has been found near
+Madeira, the other near the Fiji Islands.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pterois.</span>—Head and body compressed; scales of small or
+moderate size. Bones of the head armed with numerous spinous
+projections, between which often skinny tentacles are developed.
+The dorsal spines and pectoral rays are more or less prolonged,
+passing beyond the margin of the connecting membrane. Twelve or
+thirteen dorsal spines. Villiform teeth in the jaws and on the
+vomer.</p>
+</div>
+
+<p>Nine species are known from the tropical Indo-Pacific. They belong
+to the most singularly formed and most beautifully coloured fishes
+of the Tropics, and formerly were believed to be able to fly, like
+Dactylopterus. But the membrane connecting their pectoral rays is
+much too short and feeble to enable them to raise themselves from the
+surface of the water.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Apistus.</span>—Head and body compressed, covered with
+ctenoid scales of rather small size. Some bones of the head, and
+especially the præorbital, are armed with spines. One dorsal
+with fifteen spines; the anal with three. The pectoral fin is
+elongate, and one ray is completely detached from the fin.<span class="pagenum" id="Page_416">[416]</span>
+Villiform teeth in the jaws, on the vomer, and palatine bones.
+Air-bladder present. A cleft behind the fourth gill.</p>
+</div>
+
+<p>Two species from the Indian Ocean. These fishes are very small, but
+of interest on account of the prolongation of their pectoral fins,
+which indicates that they can take long flying leaps out of the water.
+However, this requires confirmation by actual observation.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Agriopus.</span>—Head and body compressed, scaleless; head
+without any, or with very feeble, armature. Cleft of the mouth
+small, at the end of the produced snout. One dorsal fin, which
+commences from the head, the spinous portion being formed
+by from seventeen to twenty-one strong spines; anal short.
+Villiform teeth in the jaws, generally none on the vomer.</p>
+</div>
+
+<p>Seven species. This singular genus is peculiar to the temperate parts
+of the South Pacific, occurring at the Cape, on the coast of South
+Australia, and Chili. The largest species (<i>A. torvus</i>) attains a
+length of two and a half feet. Nothing is known of its mode of life.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Synanceia.</span>—General appearance of the fish, especially
+of the head, monstrous. Scales none; skin with numerous soft
+warty protuberances or filaments. Mouth directed upwards, wide.
+Eyes small. From thirteen to sixteen dorsal spines; pectoral
+fins very large. Villiform teeth in the jaws, and sometimes on
+the vomer.</p>
+</div>
+
+<p>Four species are known from the Indo-Pacific, of which <i>S.
+horrida</i> and <i>S. verrucosa</i> are the most generally distributed,
+and, unfortunately, the most common. They are justly feared on account
+of the great danger accompanying wounds which they inflict with their
+poisoned dorsal spines, as has been already noticed above, p. 191. The
+greatest length to which they attain does not seem to exceed eighteen
+inches. They are very voracious fishes, and their stomach is of so
+great a capacity that they are able to swallow fishes one-third of
+their own bulk.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Micropus.</span>—Head and body strongly compressed, short,
+and<span class="pagenum" id="Page_417">[417]</span> deep; no scales, but the skin is covered with minute
+tubercles. Snout very short, with nearly vertical anterior
+profile. Præorbital, præ- and inter-operculum with spines on
+the edge. Dorsal fin with seven or eight, anal with two spines.
+Pectorals short, ventrals rudimentary. Jaws with villiform teeth.</p>
+</div>
+
+<p>These fishes belong to the smallest of Acanthopterygians, scarcely
+exceeding 1½ inches in length. Two species are known, which are rather
+common on the coral reefs of the Pacific.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chorismodactylus.</span>—Head and body rather compressed,
+scaleless, with skinny flaps. Bones of the head with prominent
+ridges; the præorbital, præoperculum, and operculum armed; a
+depression on the occiput. One dorsal fin, with thirteen spines;
+the anal with two. Three free pectoral appendages. Ventral fins
+with one spine and five rays. Villiform teeth in the jaws only.</p>
+</div>
+
+<p>Only one small species, <i>Ch. multibarbis</i>, is known, from the
+coasts of India and China.</p>
+
+  <div class="figcenter" id="fig181" style="max-width: 623px">
+     <img
+    class="p1"   
+    src="images/fig181.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 181.—Chorismodactylus multibarbis.</p>
+  </div>
+
+<p>To complete the list of Scorpænoid genera, we have to mention
+<i>Tænianotus</i>, <i>Centropogon</i>, <i>Pentaroge</i>,
+<i>Tetraroge</i>, <i>Prosopodasys</i>, <i>Aploactis</i>,
+<i>Trichopleura</i>, <i>Hemitripterus</i>, <i>Minous</i> and
+<i>Pelor</i>.</p>
+
+<p><span class="pagenum" id="Page_418">[418]</span></p>
+
+
+<h6 class="smcap">Eighth Family—Nandidæ.</h6>
+
+<p><i>Body oblong, compressed, covered with scales. Lateral line
+interrupted. Dorsal fin formed by a spinous and soft portion, the
+number of spines and rays being nearly equal; anal fin with three
+spines, and with the soft portion similar to the soft dorsal. Ventral
+fins thoracic, with one spine, and five or four rays. Dentition more or
+less complete, but feeble.</i></p>
+
+<p>This small family consists of two very distinct groups.</p>
+
+<p>A. <i>Plesiopina.</i> Marine fishes of small size, with pseudobranchiæ
+and only four ventral rays. <i>Plesiops</i> from the coral-reefs of the
+Indo-Pacific, and <i>Trachinops</i> from the coast of New South Wales,
+belong to this group.</p>
+
+<p>B. <i>Nandina.</i> Freshwater fishes of small size from the East
+Indies, without pseudobranchiæ, and five ventral rays. The genera are
+<i>Badis</i>, <i>Nandus</i>, and <i>Catopra</i>.</p>
+
+
+<h6 class="smcap">Ninth Family—Polycentridæ.</h6>
+
+<p><i>Body compressed, deep, scaly. Lateral line none. Dorsal and anal
+fins long, both with numerous spines, the spinous portion being the
+more developed. Ventrals thoracic, with one spine and five soft rays.
+Teeth feeble. Pseudobranchiæ hidden.</i></p>
+
+<p>Only two genera, each represented by one or two species in the Atlantic
+rivers of Tropical America, <i>Polycentrus</i> and <i>Monocirrhus</i>,
+belong to this family. They are small insectivorous fishes.</p>
+
+
+<h6 class="smcap">Tenth Family—Teuthididæ.</h6>
+
+<p><i>Body oblong, strongly compressed, covered with very small scales.
+Lateral line continuous. Eye lateral, of moderate size. A single series
+of cutting incisors in each jaw; palate toothless. One dorsal fin,
+the spinous portion being the more deve</i><i>loped;<span class="pagenum" id="Page_419">[419]</span> anal with seven
+spines. Ventral fins thoracic, with an outer and an inner spine, and
+with three soft rays between.</i></p>
+
+<p>This family consists of one very natural genus, <i>Teuthis</i>, readily
+recognised by the singular structure of the fins. In all the species
+the fin-formula is D. 13/10. A. 7/9. The incisors are small, narrow,
+and provided with a serrated edge. The air-bladder is large, and
+forked anteriorly as well as posteriorly. Their skeleton shows several
+peculiarities: the number of vertebræ is twenty-three, ten of which
+belong to the abdominal portion. The abdominal cavity is surrounded
+by a complete ring of bones, the second piece of the coracoid being
+exceedingly long, and extending along the whole length of the abdomen,
+where it is joined to a spinous process of the first interhæmal. The
+pubic bones are slender, long, firmly attached to each other, without
+leaving a free space between them. They are fastened by a long process
+which passes the symphysis of the radii, and extends on to that of the
+humeri.</p>
+
+  <div class="figcenter" id="fig182" style="max-width: 621px">
+     <img
+    class="p1"   
+    src="images/fig182.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 182.—Teuthis nebulosa, Indian Ocean.</p>
+  </div>
+
+<p>Thirty species are known, all from the Indo-Pacific; but they do not
+extend eastwards beyond 140° long., or to the Sandwich Islands. They
+are herbivorous, and do not exceed a length of fifteen inches.</p>
+
+
+<h5 class="smcap">Second Division—Acanthopterygii Beryciformes.</h5>
+
+<p><i>Body compressed, oblong, or elevated; head with large<span class="pagenum" id="Page_420">[420]</span> muciferous
+cavities which are covered with a thin skin. Ventral fins thoracic,
+with one spine and more than five soft rays</i> (<i>in</i> Monocentris
+<i>with two only</i>).</p>
+
+<p>One family only belongs to this division.</p>
+
+
+<h6 class="smcap">Family—Berycidæ.</h6>
+
+<p><i>Body short, with ctenoid scales, which are rarely absent. Eyes
+lateral, large</i> (<i>except</i> Melamphaës). <i>Cleft of the mouth
+lateral, oblique; jaws with villiform teeth; palate generally toothed.
+Opercular bones more or less armed. Eight (four) branchiostegals.</i></p>
+
+<p>This family offers several points of biological interest. All
+its members are strictly marine; but only two of the genera are
+surface-forms (<i>Holocentrum</i> and <i>Myripristis</i>). All the
+others descend considerably below the surface, and even some of the
+species of <i>Myripristis</i> habitually inhabit depths of from 50
+to 100 fathoms. <i>Polymixia</i> and <i>Beryx</i> have been found in
+345 fathoms. <i>Melamphaës</i> must live at a still greater depth,
+as we may infer from the small size of its eye; this fish is not
+likely to come nearer to the surface than to about 200 fathoms. The
+other genera named have extremely large eyes, and, therefore, may be
+assumed to ascend into such superficial strata as are still lit up
+by a certain proportion of sun-rays. The highly-developed apparatus
+for the secretion of superficial mucus, with which these fishes are
+provided, is another sign of their living at a greater depth than any
+of the preceding families of Acanthopterygians. In accordance with this
+vertical distribution, Berycoid fishes have a wide horizontal range,
+and several species occur at Madeira as well as in Japan.</p>
+
+<p>Fossil Berycoids show a still greater diversity of form than
+living; they belong to the oldest Teleosteous fishes, the majority
+of the Acanthopterygians found in the chalk being representatives
+of this family. <i>Beryx</i> has been found in<span class="pagenum" id="Page_421">[421]</span> several species,
+with other genera now extinct: <i>Pseudoberyx</i>, with abdominal
+ventrals, from Mount Lebanon; <i>Berycopsis</i>, with cycloid
+scales; <i>Homonotus</i>, <i>Stenostoma</i>, <i>Sphenocephalus</i>,
+<i>Acanus</i>, <i>Hoplopteryx</i>, <i>Platycornus</i>, with granular
+scales; <i>Podocys</i>, with a dorsal fin extending to the neck;
+<i>Acrogaster</i>, <i>Macrolepis</i>, and <i>Rhacolepis</i>, from the
+chalk of Brazil. Species of <i>Holocentrum</i> and <i>Myripristis</i>
+occur in the Monte Bolca formation.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Monocentris.</span>—Snout obtuse, convex, short; eye of
+moderate size. Villiform teeth on the palatine bones, but none
+on the vomer. Opercular bones without armature. Scales very
+large, bony, forming a rigid carapace. Ventrals reduced to a
+single strong spine and a few rudimentary rays.</p>
+</div>
+
+  <div class="figcenter" id="fig183" style="max-width: 577px">
+     <img
+    class="p1"   
+    src="images/fig183.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 183.—Monocentris japonicus.</p>
+  </div>
+
+<p>One species only is known (<i>M. japonicus</i>) from the seas off Japan
+and Mauritius. It does not attain to any size, and is not common.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hoplostethus.</span>—Snout very short and obtuse; eye large.
+Villiform teeth on the palatine bones, but none on the vomer.
+Operculum unarmed, a strong spine at the scapulary and the angle
+of the præoperculum. Scales ctenoid, of moderate size; abdominal
+edge serrated. One dorsal, with six spines; ventrals with six
+soft rays; caudal deeply forked.</p>
+</div>
+
+<p>One species only is known (<i>H. mediterraneus</i>), which<span class="pagenum" id="Page_422">[422]</span> occurs in
+the Mediterranean, the neighbouring parts of the Atlantic, and in the
+sea off Japan.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Trachichthys.</span>—Snout very short and obtuse, with
+prominent chin; eye large. Villiform teeth on the palatine
+bones and on the vomer. A strong spine at the scapulary and at
+the angle of the præoperculum. Scales rather small; abdomen
+serrated. One dorsal, with from three to six spines; ventral
+with six soft rays. Caudal forked.</p>
+</div>
+
+<p>Four species are known from New Zealand and Madeira.</p>
+
+<p><i>Anoplogaster</i> is an allied genus from tropical parts of the
+Atlantic; it is scaleless.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Beryx.</span>—Snout short, with oblique cleft of the mouth
+and prominent chin; eye large. Villiform teeth on the palatine
+bones and vomer. Opercular bones serrated; no spine at the angle
+of the præoperculum. Scales ctenoid, of moderate or large size.
+One dorsal, with several spines; ventrals with seven or more
+soft rays. Anal with four spines; caudal forked.</p>
+</div>
+
+  <div class="figcenter" id="fig184" style="max-width: 547px">
+     <img
+    class="p1"   
+    src="images/fig184.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 184.—Beryx decadactylus.</p>
+  </div>
+
+<p>Five species are known from Madeira, the tropical Atlantic, and
+the seas of Japan and Australia. The species figured is <i>B.
+decadactylus</i>, common at Madeira, and occurring<span class="pagenum" id="Page_423">[423]</span> near Japan at a
+depth of 345 fathoms; it attains a length of 1½ feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Melamphaes.</span>—Head large and thick, with very thin
+bones, nearly all the superficial bones being transformed
+into wide muciferous channels. Eye small. Palate toothless;
+no barbels; opercles not armed. Scales large, cycloid. One
+dorsal, with six spines; anal spines very feeble; caudal forked.
+Ventrals with seven rays.</p>
+</div>
+
+<p>Two species, deep-sea fishes of the Atlantic; they are very scarce, as
+only three or four specimens have been found hitherto.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Polymixia.</span>—Snout short, with the cleft of the mouth
+nearly horizontal; eye large. Two barbels at the throat.
+Opercles without armature. Scales of moderate size. One dorsal.
+Anal with three or four spines; caudal forked; ventrals with six
+or seven soft rays.</p>
+</div>
+
+<p>Three species are known: <i>P. nobilis</i> from Madeira and St. Helena,
+<i>P. lowei</i> from Cuba, and <i>P. japonica</i> from Japan; the
+latter species from a depth of 345 fathoms. Average size eighteen
+inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Myripristis.</span>—Snout short, with oblique cleft of the
+mouth and prominent chin; eye large or very large. Villiform
+teeth on the vomer and palatine bones. Opercular bones serrated;
+præoperculum without spine. Scales large, ctenoid. Two dorsals,
+the first with ten or eleven spines; anal with four spines;
+caudal forked; ventrals with seven soft rays. Air-bladder
+divided by a contraction in two parts, the anterior of which is
+connected with the organ of hearing.</p>
+</div>
+
+<p>Eighteen species from the tropical seas of both hemispheres, the
+majority living near the coast at the surface. The coloration is
+(principally) red or pink on the back and silvery on the sides. They
+attain a length of about 15 inches, and are esteemed as food.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Holocentrum.</span>—Snout somewhat projecting, with the cleft
+of the mouth nearly horizontal; eye large. Villiform teeth on
+the<span class="pagenum" id="Page_424">[424]</span> vomer and palatine bones. Opercular bones and præorbital
+serrated; operculum with two spines behind; a large spine at the
+angle of the præoperculum. Scales ctenoid, of moderate size. Two
+dorsals, the first with twelve spines; anal with four spines,
+the third being very long and strong; caudal forked. Ventrals
+with seven soft rays.</p>
+</div>
+
+  <div class="figcenter" id="fig185" style="max-width: 588px">
+     <img
+    class="p1"   
+    src="images/fig185.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 185.—<i>Holocentrum unipunctatum</i>, from the
+South Sea.</p>
+  </div>
+
+<p>About thirty species are known from the tropical seas of both
+hemispheres; all are surface fishes, and very common. The young have
+the upper part of the snout pointed and elongate, and were described as
+a distinct genus (<i>Rhynchichthys</i>). The coloration of the adult is
+uniform; red, pink, and silvery prevailing. They attain to a length of
+about 15 inches, and are esteemed as food.</p>
+
+
+<h5 class="smcap">Third Division—Acanthopterygii Kurtiformes.</h5>
+
+<p><i>One dorsal fin only, much shorter than the anal, which is long and
+many-rayed. No superbranchial organ.</i></p>
+
+<p>One family only belongs to this division.</p>
+
+
+<h6 class="smcap">Family—Kurtidæ.</h6>
+
+<p><i>Body compressed, oblong, deep in front, attenuated behind. Snout
+short. The spines of the short dorsal are few in number,<span class="pagenum" id="Page_425">[425]</span> if developed.
+Scales small or of moderate size. Villiform teeth in the jaws, on the
+vomer, and palatine bones.</i></p>
+
+<p>This family consists of a small number of species only, which form
+two distinct genera, <i>Pempheris</i> and <i>Kurtus</i>. They are
+shore fishes of tropical seas. In both the air-bladder shows some
+peculiarity: in <i>Pempheris</i> it is divided into an anterior and
+posterior portion; in <i>Kurtus</i> it is lodged within the ribs,
+which are dilated, convex, forming rings. The number of vertebræ is
+respectively twenty-four and twenty-three.</p>
+
+
+<h5 class="smcap">Fourth Division—Acanthopterygii Polynemiformes.</h5>
+
+<p><i>Two rather short dorsal fins, somewhat remote from each other; free
+filaments at the humeral arch, below the pectoral fins; muciferous
+canals of the head well developed.</i></p>
+
+<p>One family only belongs to this division.</p>
+
+
+<h6 class="smcap">Family—Polynemidæ.</h6>
+
+<p><i>Body oblong, rather compressed, covered with smooth or very feebly
+ciliated scales. Lateral line continuous. Snout projecting beyond the
+mouth, which is inferior, with lateral cleft. Eye lateral, large.
+Villiform teeth in the jaws and on the palate. Ventrals thoracic, with
+one spine and five rays.</i></p>
+
+<p>The fishes of this natural family have been divided, on slight
+differences, into three genera—<i>Polynemus</i>, <i>Pentanemus</i>,
+and <i>Galeoides</i>. They are found in rather numerous species on the
+coasts between the tropics, and the majority enter brackish or even
+fresh water. Very characteristic are the free filaments which in this
+family are organs of touch; they are inserted on the humeral arch at
+some distance from the pectoral fin; but, nevertheless, can be regarded
+only as a detached portion of that fin; they can be moved quite
+independently of the fin; their number varies from three to fourteen,
+according<span class="pagenum" id="Page_426">[426]</span> to the species; in some they are exceedingly elongate, twice
+as long as the fish, in others they are not longer or even shorter than
+the pectoral. It is evident from the whole organisation of these fishes
+that they live on muddy bottom or in thick water, such as is found
+near the mouths of great rivers. Their eyes are large, but generally
+obscured by a filmy skin, so that those feelers must be of great use
+to them in finding their way and their food. The Polynemoids are very
+useful to man: their flesh is esteemed, and some of the species are
+provided with an air-bladder which yields a good sort of isinglass,
+and forms an article of trade in the East Indies. Some of these fishes
+attain to a length of four feet.</p>
+
+  <div class="figcenter" id="fig186" style="max-width: 621px">
+     <img
+    class="p1"   
+    src="images/fig186.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 186.—<i>Pentanemus quinquarius</i>, from the West
+Coast of Africa and the West Indies.</p>
+  </div>
+
+
+<h5 class="smcap">Fifth Division—Acanthopterygii Sciæniformes.</h5>
+
+<p><i>The soft dorsal is more, generally much more, developed than the
+spinous, and than the anal. No pectoral filaments; head with the
+muciferous canals well developed.</i></p>
+
+<p>Also this division is composed of one family only.</p>
+
+
+<h6 class="smcap">Family—Sciænidæ.</h6>
+
+<p><i>Body rather elongate, compressed, covered with ctenoid scales.
+Lateral line continuous, and frequently extending over the caudal<span class="pagenum" id="Page_427">[427]</span> fin.
+Mouth in front of the snout. Eye lateral, of moderate size. Teeth in
+villiform bands, sometimes with the addition of canines; no molars or
+incisor-like teeth in the jaws; palate toothless. Præoperculum unarmed,
+and without bony stay. Ventrals thoracic, with one spine and five soft
+rays. Bones of the head with wide muciferous channels. Stomach coecal.
+Air-bladder frequently with numerous appendages</i> (see pp. 144 and
+<i>seq.</i>)</p>
+
+<p>The fishes of the “<i>Meagre</i>” family are chiefly coast-fishes of
+the tropical and sub-tropical Atlantic and Indian Oceans, preferring
+the neighbourhood of the mouths of large rivers, into which they freely
+enter, some of the species having become so completely naturalised in
+fresh water that they are never found nowadays in the sea. Some of the
+larger species wander far from their original home, and are not rarely
+found at distant localities as occasional visitors. In the Pacific
+and on the coast of Australia, where but a few large rivers enter the
+ocean, they are extremely rare and, in the Red Sea, they are absent.
+Many attain a large size, and almost all are eaten.</p>
+
+<p>No fossil species have been as yet discovered.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pogonias.</span>—Snout convex, with the upper jaw overlapping
+the lower. Mandible with numerous small barbels. No canines. The
+first dorsal with ten stout spines. Two anal spines, the second
+very strong. Scales of moderate size.</p>
+</div>
+
+<p>To this fish (<i>P. chromis</i>) more especially is given the name of
+“Drum,” from the extraordinary sounds which are produced by it and
+other allied Sciænoids. These sounds are better expressed by the word
+drumming than by any other, and are frequently noticed by persons in
+vessels lying at anchor on the coasts of the United States, where those
+fishes abound. It is still a matter of uncertainty by what means the
+“Drum” produces the sounds. Some naturalists believe that it is caused
+by the clapping together of the pharyngeal teeth, which are very large
+molar teeth. However, if it be<span class="pagenum" id="Page_428">[428]</span> true that the sounds are accompanied
+by a tremulous motion of the vessel, it seems more probable that they
+are produced by the fishes beating their tails against the bottom of
+the vessel in order to get rid of the parasites with which that part
+of their body is infested. The “Drum” attains to a length of more than
+four feet, and to a weight exceeding a hundred lbs. Its air-bladder has
+been figured on p. 146.</p>
+
+<p><i>Micropogon</i> is closely allied to <i>Pogonias</i>, but has conical
+pharyngeal teeth. Two species from the western parts of the Atlantic.</p>
+
+  <div class="figcenter" id="fig187" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig187.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 187.—Pharyngeal bones and teeth of <i>Pogonias
+chromis</i>. A, Upper; B, Lower pharyngeals.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Umbrina.</span>—Snout convex, with the upper jaw overlapping
+the lower; a short barbel under the symphysis of the mandible.
+The first dorsal with nine or ten flexible spines, the anal with
+one or two. Scales of moderate size.</p>
+</div>
+
+  <div class="figcenter" id="fig188" style="max-width: 414px">
+     <img
+    class="p1"   
+    src="images/fig188.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 188.—<i>Umbrina nasus</i>, from Panama.</p>
+  </div>
+
+<p>Twenty species are known from the Mediterranean,<span class="pagenum" id="Page_429">[429]</span> Atlantic, and Indian
+Ocean. One well known to the ancients, under the name of <i>Umbra</i>,
+is the <i>Umbrina cirrhosa</i> of the Mediterranean, the “Umbrine”
+or “Ombre” of the French, and the “Corvo” of the Italians. It ranges
+to the Cape of Good Hope, and attains a length of three feet. Also
+on the coasts of the United States several species occur, as <i>U.
+alburna</i>, <i>U. nebulosa</i>, etc.</p>
+
+  <div class="figcenter" id="fig189" style="max-width: 411px">
+     <img
+    class="p1"   
+    src="images/fig189.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 189.—<i>Umbrina nasus</i>, from Panama.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sciæna</span> (including <i>Corvina</i>).—The upper jaw
+overlapping the lower, or both jaws equal in front. Interorbital
+space moderately broad and slightly convex. Cleft of the mouth
+horizontal or slightly oblique. The outer series of teeth is
+generally composed of teeth larger than the rest, but there are
+no canines. Eye of moderate size, barbel none.</p>
+</div>
+
+  <div class="figcenter" id="fig190" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig190.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 190.—Sciæna richardsonii.</p>
+  </div>
+
+<p>Some fifty species are known, but their distinctive characters have
+been but imperfectly pointed out. They are found<span class="pagenum" id="Page_430">[430]</span> in all the seas
+and rivers in which Sciænoids generally occur, and many are entirely
+confined to fresh water, for instance the species figured, <i>Sciæna
+richardsonii</i>, from Lake Huron; <i>Sc. amazonica</i>; <i>Sc.
+obliqua</i>, <i>ocellata</i>, <i>oscula</i>, etc., from fresh waters
+of the United States. <i>Sciæna diacanthus</i> and <i>Sc. coitor</i>
+belong to the most common fishes of the coasts of the East Indies,
+ascending the great rivers for a long distance from the sea. One of
+the European species, <i>Sciæna aquila</i>, has an extremely wide
+range; it not rarely reaches the British coasts, where it is known
+as “Meagre,” and has been found at the Cape of Good Hope and on the
+coast of southern Australia. Like some of the other species it attains
+to a length of six feet, but the majority of the species of this
+genus remain within smaller dimensions. A part of the species have
+the second anal ray very strong, and have been placed into a distinct
+genus, <i>Corvina</i>,—thus, among others, <i>Sc. nigra</i> from the
+Mediterranean, and <i>Sc. richardsonii</i>.</p>
+
+<p><i>Pachyurus</i> is closely allied to <i>Sciæna</i>, but has the
+vertical fins densely covered with small scales.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Otolithus.</span>—Snout obtuse or somewhat pointed, with
+the lower jaw longer. The first dorsal with nine or ten feeble
+spines. Canine teeth more or less distinct. Præoperculum
+denticulated. Scales of moderate or small size.</p>
+</div>
+
+<p>About twenty species are known from the tropical and sub-tropical parts
+of the Atlantic and Indian Oceans. The air-bladder is figured on p. 144.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ancylodon</span> differs from <i>Otolithus</i> in having very
+long arrow-shaped or lanceolate canine teeth. Coasts of tropical
+America.</p>
+
+<p><span class="smcap">Collichthys.</span>—Body elongate; head very broad, with the
+upper surface very convex; cleft of the mouth wide and oblique;
+no large canines. Eye small. No barbel. Scales small, or of
+moderate size. The second dorsal very long, caudal pointed.</p>
+</div>
+
+<p>Three species from the East Indian and Chinese coasts. The great
+development of the muciferous system on the head<span class="pagenum" id="Page_431">[431]</span> and the small eye
+leads one to suppose that these fishes live in muddy water near the
+mouths of large rivers. The air-bladder has been described on p. 144.</p>
+
+<p>Other genera belonging to this family are <i>Larimus</i>, <i>Eques</i>,
+<i>Nebris</i>, and <i>Lonchurus</i>.</p>
+
+  <div class="figcenter" id="fig191" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig191.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 191.—Histiophorus pulchellus.</p>
+  </div>
+
+
+<h5 class="smcap">Sixth Division—Acanthopterygii Xiphiiformes.</h5>
+
+<p><i>The upper jaw is produced into a long cuneiform weapon.</i></p>
+
+<p>These fishes form one small family only, <i>Xiphiidæ</i>.</p>
+
+<p>The “Sword-fishes” are pelagic fishes, occurring in all tropical and
+sub-tropical seas. Generally found in the open ocean, always vigilant,
+and endowed with extraordinary strength and velocity, they are but
+rarely captured, and still more rarely preserved. The species found in
+the Indian and Pacific Oceans belong to the genus <i>Histiophorus</i>,
+distinguished from the common Mediterranean Sword-fish, or
+<i>Xiphias</i>, by the presence of ventral fins, which, however, are
+reduced to two long styliform appendages. The distinction of the
+species is beset with great difficulties, owing to the circumstance
+that but few examples exist in museums, and further, because the form
+of the dorsal fin, the length of the ventrals, the shape and length of
+the sword, appear to change according to the age of the individuals.
+Some specimens or species have only the anterior dorsal rays elevated,
+the remainder of<span class="pagenum" id="Page_432">[432]</span> the fin being very low, whilst in others all the
+rays are exceedingly elongate, so that the fin, when erected, projects
+beyond the surface of the water. It is stated that Sword-fishes, when
+quietly floating with the dorsal fin erect, can sail before the wind,
+like a boat.</p>
+
+<p>Sword-fishes are the largest of Acanthopterygians, and not exceeded in
+size by any other Teleostean; they attain to a length of from 12 to 15
+feet, and swords have been obtained more than three feet long, and with
+a diameter of at least three inches at the base. The sword is formed by
+the prolongation and coalescence of the maxillary and intermaxillary
+bones; it is rough at its lower surface, owing to the development
+of rudimentary villiform teeth, very hard and strong, and forms a
+most formidable weapon. Sword-fishes never hesitate to attack whales
+and other large Cetaceans, and by repeatedly stabbing these animals
+generally retire from the combat victorious. The cause which excites
+them to those attacks is unknown; but they follow this instinct so
+blindly that they not rarely attack boats or large vessels in a similar
+manner, evidently mistaking them for Cetaceans. Sometimes they actually
+succeed in piercing the bottom of a ship, endangering its safety; but
+as they are unable to execute powerful backward movements they cannot
+always retract their sword, which is broken off by the exertions of the
+fish to free itself. A piece of a two-inch plank of a whale-boat, thus
+pierced by a sword-fish, in which the broken sword still remains, is
+preserved in the British Museum.</p>
+
+<p>The Rev. Wyatt Gill, who has worked as a missionary for many years in
+the South Sea Islands, communicates that young Sword-fishes are easily
+caught in strong nets, but no net is strong enough to hold a fish of
+six feet in length. Specimens of that size are now and then captured
+by hook and line, a small fish being used as bait. Individuals with
+the sword broken off are not rarely observed. Larger specimens<span class="pagenum" id="Page_433">[433]</span> cannot
+be captured by the natives, who are in great fear of them. They easily
+pierce their canoes, and only too often dangerously wound persons
+sitting in them.</p>
+
+<p>The Mediterranean Sword-fish is constantly caught in the nets of the
+Tunny-fishers off the coast of Sicily, and brought to market, where its
+flesh sells as well as that of the Tunny.</p>
+
+<p>The remarkable changes which Sword-fishes undergo at an early stage of
+their growth have been noticed above, p. 173 and <i>seq.</i></p>
+
+<p>Sword-fishes are as old a type as the Berycoids. Their remains have
+been found in the chalk of Lewes, and more frequently in the London
+clay of Sheppy, where an extinct genus, <i>Coelorhynchus</i>, has been
+recognised.</p>
+
+
+<h5 class="smcap">Seventh Division—Acanthopterygii Trichiuriformes.</h5>
+
+<p><i>Body elongate, compressed or band-like; cleft of the mouth wide,
+with several strong teeth in the jaws or on the palate. The spinous
+and soft portions of the dorsal fin and the anal are of nearly equal
+extent, long, many-rayed, sometimes terminating in finlets; caudal fin
+forked, if present.</i></p>
+
+
+<h6 class="smcap">Family—Trichiuridæ.</h6>
+
+<p>Marine fishes inhabiting the tropical and sub-tropical seas; some of
+them are surface-fishes, living in the vicinity of the coast, whilst
+others descend to moderate depths, as the Berycoids. All are powerful
+rapacious fishes, as is indicated by their dentition.</p>
+
+<p>The oldest of the extinct genera are <i>Enchodus</i> and
+<i>Anenchelum</i>; they were formerly referred to the Scombroids,
+but belong to this family. The former has been found in the chalk
+of Lewes and Mæstricht; the latter is abundant in the Eocene
+schists of Glaris. <i>Anenchelum</i> is much elongate, and exhibits
+in the slender structure of its bones the characteristics<span class="pagenum" id="Page_434">[434]</span> of a
+deep-sea fish; it resembles much <i>Lepidopus</i>, but has some long
+rays in the ventrals. Other Eocene genera are <i>Nemopteryx</i>
+and <i>Xiphopterus</i>. In the Miocene of Licata in Sicily
+<i>Trichiuridæ</i> are well represented, viz. by a species of
+<i>Lepidopus</i>, and by two genera, <i>Hemithyrsites</i> and
+<i>Trichiurichthys</i>, which are allied to <i>Thyrsites</i> and
+<i>Trichiurus</i>, but covered with scales.</p>
+
+<p>The following is a complete list of the genera referred to this
+family:—</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Nealotus.</span>—Body incompletely clothed with delicate
+scales. Small teeth in the jaws and on the palatine bones;
+none on the vomer. Two dorsal fins, the first continuous and
+extending to the second; finlets behind the second and anal
+fins. Each ventral fin represented by a single small spine. A
+dagger-shaped spine behind the vent. Caudal fin well developed.</p>
+</div>
+
+<p>One specimen only of this fish (<i>N. tripes</i>), 10 inches long, has
+been obtained off Madeira; it evidently lives at a considerable depth,
+and comes to the surface only by accident.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Nesiarchus.</span>—Body covered with small scales. Several
+strong fangs in the jaws; no teeth on the palate. First dorsal
+not extending to the second. No detached finlets. Ventrals
+small, but perfectly developed, thoracic. Caudal fin present. A
+dagger-shaped spine behind the vent.</p>
+</div>
+
+<p>A rather large fish (<i>N. nasutus</i>), very rarely found in the sea
+off Madeira. The two or three specimens found hitherto measure from
+three to four feet in length. Probably living at the same depth as the
+preceding genus.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aphanopus.</span>—Scales none. Two very long dorsal fins;
+caudal well developed; ventrals none. A strong dagger-shaped
+spine behind the vent. Strong teeth in the jaws; none on the
+palate.</p>
+</div>
+
+<p>One species only is known, named <i>A. carbo</i> from its coal-black
+colour; it is evidently a deep-sea fish, very rarely obtained in the
+sea off Madeira. Upwards of four feet long.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Euoxymetopon.</span>—Body naked, very long and thin.
+Profile<span class="pagenum" id="Page_435">[435]</span> of the head regularly decurved from the nape to the
+snout, the occiput and forehead being elevated and trenchant.
+Jaws with fangs; palatine teeth present. One dorsal only,
+continued from the head to the caudal fin, which is distinct.
+A dagger-shaped spine behind the vent. Pectoral fins inserted
+almost horizontally, with the lowest rays longest, and with
+the posterior border emarginate. Ventral fins rudimentary,
+scale-like.</p>
+</div>
+
+<p>This is another deep-sea form of this family, but, at present, no
+observations have been made as regards the exact depth at which it
+occurs. A specimen has been known since the year 1812; it was found on
+the coast of Scotland, and described as <i>Trichiurus lepturus</i>. The
+same species has been re-discovered in the West Indies, where, however,
+it is also extremely scarce.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lepidopus.</span>—Body band-like; one single dorsal extends
+along the whole length of the back; caudal well developed.
+Ventrals reduced to a pair of scales. Scales none. Several fangs
+in the jaws; teeth on the palatine bones.</p>
+</div>
+
+  <div class="figcenter" id="fig192" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig192.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 192.—Lepidopus caudatus.</p>
+  </div>
+
+<p>The Scabbard-fish (<i>L. caudatus</i>) is rather common in the
+Mediterranean and warmer parts of the Atlantic, extending northwards
+to the south coast of England, where it is an occasional visitor, and
+southwards to the Cape of Good Hope. More recently it has been observed
+on the coasts of Tasmania and New Zealand. We may, therefore, justly
+consider it to be a deep-sea fish, which probably descends to the same
+depth<span class="pagenum" id="Page_436">[436]</span> as the preceding allied forms. It grows to a length of five or
+six feet, but its body is so much compressed that it does not weigh
+more than as many pounds. It is well known in New Zealand, where it is
+called “Frost-fish,” and esteemed as the most delicious fish of the
+colony. A still more attenuated species (<i>L. tenuis</i>) occurs in
+the sea off Japan, at a depth of some 340 fathoms.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Trichiurus.</span>—Body band-like, tapering into a fine
+point, without caudal fin. One single dorsal extending the whole
+length of the back. Ventrals reduced to a pair of scales, or
+entirely absent. Anal fin rudimentary, with numerous extremely
+short spines, scarcely projecting beyond the skin. Long fangs in
+the jaws; teeth on the palatine bones, none on the vomer.</p>
+</div>
+
+<p>The “Hairtails” belong to the tropical marine fauna, and although
+generally found in the vicinity of land, they wander frequently out to
+sea, perhaps merely because they follow some ocean-currents. Therefore
+they are not rarely found in the temperate zone, the common West Indian
+species (<i>T. lepturus</i>), for instance, on the coast of England.
+They attain to a length of about four feet. The number of their
+vertebræ is very large, as many as 160, and more. Six species are known.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Epinnula.</span>—Body rather elongate, covered with minute
+scales,[*. see below] The first dorsal fin continuous, with
+spines of moderate strength, and extending on to the second;
+finlets none; ventrals well developed. Lateral lines two. Teeth
+of the jaws strong; palatine teeth, none.</p>
+</div>
+
+<p>The “Domine” of the Havannah, <i>E. magistralis</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Thyrsites.</span>—Body rather elongate, for the greater part
+naked. The first dorsal continuous, with the spines of moderate
+strength, and extending on to the second. From two to six
+finlets behind the dorsal and anal. Several strong teeth in the
+jaws; teeth on the palatine bones.</p>
+</div>
+
+<p>The species of this genus attain to a considerable size (from four
+to five feet), and are valuable food fishes; <i>Th. atun</i><span class="pagenum" id="Page_437">[437]</span> from
+the Cape of Good Hope, South Australia, New Zealand, and Chili, is
+preserved, pickled or smoked. In New Zealand it is called “Barracuda”
+or “Snoek,” and exported from the colony into Mauritius and Batavia
+as a regular article of commerce, being worth over £17 a ton; <i>Th.
+pretiosus</i>, the “Escholar” of the Havannah, from the Mediterranean,
+the neighbouring parts of the Atlantic, and the West Indies; <i>Th.
+prometheus</i> from Madeira, Bermuda, St. Helena, and Polynesia; <i>Th.
+solandri</i> from Amboyna and Tasmania is probably the same as <i>Th.
+prometheus</i>.</p>
+
+<p>Young specimens of this (or, perhaps, the following) genus have been
+described as <i>Dicrotus</i>. In them the finlets are not yet detached
+from the rest of the fin; and the ventral fins, which are entirely
+obsolete in the adult fish, are represented by a long crenulated spine.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gempylus.</span>—Body very elongate, scaleless. The first
+dorsal fin continuous, with thirty and more spines, and
+extending on to the second. Six finlets behind the dorsal and
+anal. Several strong teeth in the jaws, none on the palate.</p>
+</div>
+
+<p>One species (<i>G. serpens</i>), inhabiting considerable depths of the
+Atlantic and Pacific Oceans.</p>
+
+<h6 class="smcap">Family—Palæorhynchidæ.</h6>
+
+<p>This family has been formed for two extinct genera:
+<i>Palæorhynchus</i> from the schists of Glaris, and
+<i>Hemirhynchus</i> from tertiary formations near Paris. These genera
+resemble much the <i>Trichiuridæ</i> in their long, compressed body,
+and long vertical fins, but their jaws, which are produced into a long
+beak, are toothless, or provided with very small teeth. The dorsal fin
+extends the whole length of the back, and the anal reaches from the
+vent nearly to the caudal, which is forked. The ventrals are composed
+of several rays and thoracic. The vertebræ long, slender, and numerous,
+and, like all the bones of the skeleton, thin, indicating that these
+fishes<span class="pagenum" id="Page_438">[438]</span> were inhabitants of considerable depths of the ocean. Both
+the jaws of <i>Palæorhynchus</i> are prolonged into a beak, whilst in
+<i>Hemirhynchus</i> the upper exceeds the lower in length.</p>
+
+
+<h5 class="smcap">Eighth Division—Acanthopterygii Cotto-scombriformes.</h5>
+
+<p><i>Spines developed, in one of the fins at least. Dorsal fins either
+continuous or close together; the spinous dorsal, if present, always
+short; sometimes modified into tentacles, or into a suctorial disk;
+soft dorsal always long, if the spinous is absent; anal similarly
+developed as the soft dorsal, and both generally much longer than
+the spinous, sometimes terminating in finlets. Ventrals, thoracic or
+jugular, if present, never modified into an adhesive apparatus. No
+prominent anal papilla.</i></p>
+
+<p>Marine fishes, with few exceptions.</p>
+
+
+<h6 class="smcap">First Family—Acronuridæ.</h6>
+
+<p><i>Body compressed, oblong or elevated, covered with minute scales.
+Tail generally armed with one or more bony plates or spines, which
+are developed with age, but absent in very young individuals. Eye
+lateral, of moderate size. Mouth small; a single series of more or
+less compressed, sometimes denticulated, sometimes pointed incisors in
+each jaw; palate toothless. One dorsal fin, the spinous portion being
+less developed than the soft; anal with two or three spines; ventral
+fins thoracic. Air-bladder forked posteriorly. Intestines with more
+or less numerous circumvolutions. Nine abdominal, and thirteen caudal
+vertebræ.</i></p>
+
+<p>Inhabitants of the tropical seas, and most abundant on coral-reefs.
+They feed either on vegetable substances or on the superficial animal
+matter of corals.</p>
+
+<p>Extinct species of <i>Acanthurus</i> and <i>Naseus</i> have been
+discovered in the Monte Bolca formation.</p>
+
+<p><span class="pagenum" id="Page_439">[439]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acanthurus.</span>—Jaws with a single series of lobate
+incisors, which are sometimes movable. An erectile spine hidden
+in a groove on each side of the tail. Ventral fins with one
+spine and generally five rays. Scales ctenoid, sometimes with
+minute spines. Branchiostegals five.</p>
+</div>
+
+<p>The fishes of this genus, which sometimes are termed “Surgeons,”
+are readily recognised by the sharp lancet-shaped spine with which
+each side of the tail is armed. When at rest the spine is hidden
+in a sheath; but it can be erected and used by the fish as a very
+dangerous weapon, by striking with the tail towards the right and
+left. “Surgeons” occur in all tropical seas, with the exception of the
+eastern part of the Pacific, where they disappear with the corals. They
+do not attain to any size, the largest species scarcely exceeding a
+length of eighteen inches. Many are agreeably or showily coloured, the
+ornamental colours being distributed in very extraordinary patterns.
+The larger species are eatable, and some even esteemed as food. It
+is stated that the fry of some species periodically approaches, in
+immense numbers, the coasts of some of the South Sea Islands (Caroline
+Archipelago), and serves as an important article of food to the
+natives. Nearly fifty species are known.</p>
+
+  <div class="figcenter" id="fig193" style="max-width: 593px">
+     <img
+    class="p1"   
+    src="images/fig193.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 193.—Acanthurus leucosternum, Indian Ocean.</p>
+  </div>
+
+<p>At an early period of their growth these fishes present so different an
+aspect that they were considered a distinct genus, <i>Acronurus</i>.
+The form of the body is more circular and exceedingly<span class="pagenum" id="Page_440">[440]</span> compressed. No
+scales are developed, but the skin forms numerous oblique parallel
+folds. The gill-cover and the breast are shining silvery.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Naseus.</span>—Tail with two (rarely one or three) bony
+keeled plates on each side (in the adult). Head sometimes with
+a bony horn or crest-like prominence directed forwards. Ventral
+fins composed of one spine and three rays. From four to six
+spines in the dorsal; two anal spines. Scales minute, rough,
+forming a sort of fine shagreen. Air-bladder forked behind.
+Intestinal tract with many circumvolutions.</p>
+</div>
+
+<p>Twelve species are known from the tropical Indo-Pacific, but none of
+them extend eastwards beyond the Sandwich Islands. In their mode of
+life these fishes resemble the <i>Acanthuri</i>. Likewise, the young
+have a very different appearance, and are unarmed, and were described
+as a distinct genus, <i>Keris</i>. One of the most common species is
+<i>N. unicornis</i>, which, when adult (22 inches long), has a horn
+about 2 inches long, whilst it is merely a projection in front of the
+eye in individuals of 7 inches in length.</p>
+
+<p><i>Prionurus</i> is an allied genus with a series of several keeled
+bony laminæ on each side of the tail.</p>
+
+  <div class="figcenter" id="fig194" style="max-width: 639px">
+     <img
+    class="p1"   
+    src="images/fig194.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 194.—Naseus unicornis.</p>
+  </div>
+
+
+<h6 class="smcap">Second Family—Carangidæ.</h6>
+
+<p><i>Body more or less compressed, oblong or elevated, covered with small
+scales or naked; eye, lateral. Teeth, if present, conical. No bony
+stay for the præoperculum. The spinous dorsal is less developed than
+the soft or than the anal, either continuous with, or separated from,
+the soft portion; sometimes rudimentary.<span class="pagenum" id="Page_441">[441]</span> Ventrals thoracic, sometimes
+rudimentary or entirely absent. No prominent papilla near the vent.
+Gill-opening wide. Ten abdominal and fourteen caudal vertebræ.</i></p>
+
+  <div class="figcenter" id="fig195" style="max-width: 313px">
+     <img
+    class="p1"   
+    src="images/fig195.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 195.—Semiophoris velitans.</p>
+  </div>
+
+<p>Inhabitants of tropical and temperate seas. Carnivorous. They
+appear first in cretaceous formations, where they are represented
+by <i>Platax</i> and some Caranx-like genera (<i>Vomer</i> and
+<i>Aipichthys</i> from the chalk of Comen in Istria). They
+are more numerous in various Tertiary formations, especially
+in the strata of Monte Bolca, where some still existing
+genera<span class="pagenum" id="Page_442">[442]</span> occur, as <i>Zanclus</i>, <i>Platax</i>, <i>Caranx</i>
+(<i>Carangopsis</i>), <i>Argyriosus</i> (<i>Vomer</i>), <i>Lichia</i>,
+<i>Trachynotus</i>. Of the extinct genera the following belong to
+this family:—<i>Pseudovomer</i> (<i>Licata</i>), <i>Amphistium</i>,
+<i>Archæus</i>, <i>Ductor</i>, <i>Plionemus</i> (?), and
+<i>Semiophorus</i>. <i>Equula</i> has been recently discovered in the
+Miocene marls of Licata in Sicily.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Caranx</span> (including <i>Trachurus</i>).—Body more or
+less compressed, sometimes sub-cylindrical. Cleft of the mouth
+of moderate width. The first dorsal fin continuous, with about
+eight feeble spines, sometimes rudimentary; the soft dorsal and
+anal are succeeded by finlets in a few species. Two anal spines,
+somewhat remote from the fin. Scales very small. Lateral line
+with an anterior curved, and a posterior straight, portion,
+either entirely or posteriorly only covered by large plate-like
+scales, several of which are generally keeled, the keel ending
+in a spine. Dentition feeble. Air-bladder forked posteriorly.</p>
+</div>
+
+  <div class="figcenter" id="fig196" style="max-width: 558px">
+     <img
+    class="p1"   
+    src="images/fig196.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 196.—Plates of the lateral line of Caranx hippos.</p>
+  </div>
+
+<p>The “Horse-mackerels” are found in abundance in almost all temperate
+and, especially, tropical seas. Many species wander to other parts
+of the coast, or to some distance from land, and have thus gradually
+extended their range over two or more oceanic areas; some are found
+in all tropical seas. The species described are very numerous, about
+ninety having been properly characterised and distinguished. Some
+attain to a length of three feet and more, and all are eatable. They
+feed on other fish and various marine animals.</p>
+
+<p>Of the most noteworthy species the following may be mentioned:—<i>C.
+trachurus</i>, the common British Horse-mackerel, distinguished
+by having the lateral line in its whole length armed with large
+vertical plates; it is almost cosmopolitan within the temperate and
+tropical zones of the northern and<span class="pagenum" id="Page_443">[443]</span> southern hemispheres. <i>C.
+crumenophthalmus</i>, <i>C. carangus</i>, and <i>C. hippos</i>, three
+of the most common sea-fishes, equally abundant in the Atlantic
+and Indo-Pacific oceans; <i>C. ferdau</i>, from the Indo-Pacific,
+upwards of three feet in length. <i>C. armatus</i>, <i>ciliaris</i>,
+<i>gallus</i>, etc., which have an exceedingly short and compressed
+body, with rudimentary spinous dorsal fin, and with some of the rays of
+the dorsal and anal prolonged into filaments.</p>
+
+  <div class="figcenter" id="fig197" style="max-width: 517px">
+     <img
+    class="p1"   
+    src="images/fig197.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 197.—Caranx ferdau.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Argyriosus</span> is closely allied to <i>Caranx</i>,
+especially to the last-named species, but the lateral line has
+no plates whatever; and the body is scaleless, chiefly of a
+bright silvery colour.</p>
+</div>
+
+<p>Two species from the tropical Atlantic.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Micropteryx.</span>—Body much compressed, with prominent
+trenchant abdomen, covered with small scales; lateral line
+not shielded; præopercular margin entire. Cleft of the mouth
+rather small; præorbital of moderate width. The first dorsal
+continuous, with seven feeble spines. No detached finlets. Small
+teeth on the vomer and palatine bones.</p>
+</div>
+
+<p><span class="pagenum" id="Page_444">[444]</span></p>
+
+<p><i>Micropteryx chrysurus</i> is a semi-pelagic fish, and very common in
+the tropical Atlantic, less so in the Indian Ocean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Seriola.</span>—Body oblong, slightly compressed, with
+rounded abdomen, covered with very small scales; lateral line
+not shielded; præopercular margin entire. Cleft of the mouth of
+moderate width, or rather wide. The first dorsal continuous,
+with feeble spines. No detached finlets. Villiform teeth in the
+jaws, on the vomer and palatine bones.</p>
+</div>
+
+<p>These fishes are often called “Yellow-tails,” and occur in nearly
+all the temperate and tropical seas, sometimes at a great distance
+from land. Twelve species are known, and the majority have a wide
+geographical range. The larger grow to a length of from four to five
+feet, and are esteemed as food, especially at St. Helena, the Cape of
+Good Hope, in Japan, Australia, and New Zealand.</p>
+
+<p><i>Seriolella</i> and <i>Seriolichthys</i>, the latter from the
+Indo-Pacific, and distinguished by a finlet behind the dorsal and anal,
+are allied genera.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Naucrates.</span>—Body oblong, sub-cylindrical, covered with
+small scales; a keel on each side of the tail. The spinous
+dorsal consists of a few short free spines; finlets none.
+Villiform teeth in the jaws, on the vomer and palatine bones.</p>
+</div>
+
+<p>The “Pilot-fish” (<i>N. ductor</i>) is a truly pelagic fish, known in
+all tropical and temperate seas. Its name is derived from its habit of
+keeping company with ships and large fish, especially Sharks. It is the
+<i>Pompilus</i> of the ancients, who describe it as pointing out the
+way to dubious or embarrassed sailors, and as announcing the vicinity
+of land by its sudden disappearance. It was therefore regarded as a
+sacred fish. The connection between the Shark and the Pilot-fish has
+received various interpretations, some observers having perhaps added
+more sentiment than is warranted by the actual facts. It was stated
+that the Shark never seized the Pilot-fish, that the<span class="pagenum" id="Page_445">[445]</span> latter was of
+great use to its big companion in conducting it and showing it the way
+to its food. Dr. Meyen in his “Reise um die Erde” states: “The pilot
+swims constantly in front of the Shark; we ourselves have seen three
+instances in which the Shark was led by the Pilot. When the Shark
+neared the ship the Pilot swam close to the snout, or near one of the
+pectoral fins of the animal. Sometimes he darted rapidly forwards or
+sidewards as if looking for something, and constantly went back again
+to the Shark. When we threw overboard a piece of bacon fastened on a
+great hook, the Shark was about twenty paces from the ship. With the
+quickness of lightning the Pilot came up, smelt at the dainty, and
+instantly swam back again to the Shark, swimming many times round his
+snout and splashing, as if to give him exact information as to the
+bacon. The Shark now began to put himself in motion, the Pilot showing
+him the way, and in a moment he was fast upon the hook.<a id="FNanchor_42" href="#Footnote_42" class="fnanchor">[42]</a> Upon a
+later occasion we observed two Pilots in sedulous attendance on a Blue
+Shark, which we caught in the Chinese Sea. It seems probable that the
+Pilot feeds on the Sharks’ excrements, keeps his company for that
+purpose, and directs his operations solely from this selfish view.” We
+believe that Dr. Meyen’s opinion, as expressed in his last words, is
+perfectly correct. The Pilot obtains a great part of his food directly
+from the Shark, in feeding on the parasitic crustaceans with which
+Sharks and other large fish are infested, and on the smaller pieces of
+flesh which are left unnoticed by the Shark when it tears its prey.
+The Pilot also, being a small fish, obtains greater security when in
+company of a Shark, which would keep at a distance all other fishes of
+prey that would be likely to prove dangerous to the Pilot. Therefore,
+in accompanying the Shark, the Pilot is led by the same instinct which
+makes it follow a ship.<span class="pagenum" id="Page_446">[446]</span> With regard to the statement that the Pilot
+itself is never attacked by the Shark all observers agree as to its
+truth; but this may be accounted for in the same way as the impunity
+of the swallow from the hawk, the Pilot-fish being too nimble for the
+unwieldy Shark.</p>
+
+<p>The Pilot-fish does not always leave the vessels on their approach
+to land. In summer, when the temperature of the sea-water is several
+degrees above the average, Pilots will follow ships to the south
+coast of England into the harbour, where they are generally speedily
+caught. Pilot-fish attain a length of 12 inches only. When very young
+their appearance differs so much from the mature fish that they have
+been described as a distinct genus, <i>Nauclerus</i>. This fry is
+exceedingly common in the open ocean, and constantly obtained in the
+tow-net; therefore the Pilot-fish retains its pelagic habits also
+during the spawning season, and some of the spawn found by voyagers
+floating on the surface is, without doubt, derived from this species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chorinemus.</span>—Body compressed, oblong; covered with
+small scales, singularly shaped, lanceolate, and hidden in
+the skin. The first dorsal is formed by free spines in small
+numbers; the posterior rays of the second dorsal and anal are
+detached finlets. Small teeth in the jaws, on the vomer and
+palatine bones.</p>
+</div>
+
+<p>Twelve species are known from the Atlantic and Indo-Pacific; some enter
+brackish water, whilst others are more numerous at some distance from
+the shore. They attain to a length of from 2 to 4 feet. In the young,
+which have been described as <i>Porthmeus</i>, the spines and finlets
+are connected by membrane with the rest of the fin.</p>
+
+<p><i>Lichia</i> is an allied genus from the Mediterranean, tropical
+Atlantic, and the coast of Chili; five species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Temnodon.</span>—Body oblong, compressed, covered with
+cycloid scales of moderate size. Cleft of the mouth rather wide.
+Jaws with a series of strong teeth; smaller ones on the vomer
+and<span class="pagenum" id="Page_447">[447]</span> the palatine bones. The first dorsal with eight feeble
+spines connected by membrane; finlets none. Lateral line not
+shielded. The second dorsal and anal covered with very small
+scales.</p>
+</div>
+
+<p><i>Temnodon saltator</i>, sometimes called “Skip-jack,” is spread over
+nearly all the tropical and sub-tropical seas; it frequents principally
+the coasts, but is also met with in the open sea. On the coasts of the
+United States it is well known by the name of “Blue-fish,” being highly
+esteemed as food, and furnishing excellent sport. It is one of the most
+rapacious fishes, destroying an immense number of other shore-fishes,
+and killing many more than they can devour. It grows to a length of 5
+feet, but the majority of those brought to market are not half that
+length.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Trachynotus.</span>—Body more or less elevated, compressed,
+covered with very small scales. Cleft of the mouth rather small,
+with short convex snout. Opercles entire. The first dorsal
+composed of free spines in small number. No finlets. Teeth
+always small, and generally lost with age.</p>
+</div>
+
+<p>Ten species are known from the tropical Atlantic and Indo-Pacific; they
+rarely exceed a length of 20 inches. Some of the most common marine
+fishes belong to this genus, for instance <i>T. ovatus</i>, which
+ranges over the entire tropical zone.</p>
+
+<p><span class="smcap">Pammelas</span> (<i>perciformis</i>) is allied to the preceding
+genus; from the coast of New York.</p>
+
+  <div class="figcenter" id="fig198" style="max-width: 299px">
+     <img
+    class="p1"   
+    src="images/fig198.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 198.—Magnified scale of Psettus argenteus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Psettus.</span>—Body much compressed and elevated; snout
+rather short. One dorsal, entirely covered with scales, with
+seven or eight spines; anal fin with three. Ventrals very small,
+rudimentary. Teeth villiform; no teeth on the palate. Scales
+small, ctenoid.</p>
+</div>
+
+<p>Only three species are known; one, <i>P. sebæ</i>, from the west coast
+of Africa, the two<span class="pagenum" id="Page_448">[448]</span> others from the Indo-Pacific. <i>P. argenteus</i>
+is a very common fish, attaining to a length of about 10 inches.</p>
+
+  <div class="figcenter" id="fig199" style="max-width: 415px">
+     <img
+    class="p1"   
+    src="images/fig199.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 199.—Psettus argenteus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Platax.</span>—Body much compressed and elevated; snout very
+short. One dorsal, with the spinous portion nearly entirely
+hidden, and formed by from three to seven spines; anal with
+three. Ventrals well developed, with one spine and five rays.
+Teeth setiform, with an outer series of rather larger teeth,
+notched at the top; palate toothless. Scales of moderate size or
+rather small.</p>
+</div>
+
+<p>These fishes are called “Sea-bats,” from the extraordinary length of
+some portion of their dorsal and anal fins and of their ventrals. These
+long lobes are generally of a deep black colour. In mature and old
+individuals the fin-rays are much shorter than in the young, which have
+been described as distinct species. There are probably not more than
+seven species of “Sea-bats,” if so many, and they all belong to the
+Indian Ocean and Western Pacific, where they are very common.</p>
+
+<p><span class="pagenum" id="Page_449">[449]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Zanclus.</span>—Body much compressed and elevated. One
+dorsal, with seven spines, the third of which is very elongate.
+No teeth on the palate. Scales minute, velvety.</p>
+</div>
+
+<p>One species (<i>Z. cornutus</i>), which is extremely common in the
+Indo-Pacific. It is easily recognised by its snout, which is produced
+like that of <i>Chelmon</i>, and by the broad black bands crossing
+the yellow ground-colour. It attains to a length of eight inches, and
+undergoes during growth similar changes as <i>Acanthurus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Anomalops.</span>—Body oblong, covered with small, rough
+scales. Snout very short, convex, with wide cleft of the mouth.
+Eyes very large; below the eye, in a cavity of the infraorbital
+ring, there is a glandular phosphorescent organ. Villiform teeth
+in the jaws and on the palatine bones, none on the vomer. First
+dorsal fin short, with a few feeble spines connected by membrane.</p>
+</div>
+
+<p>This genus, of which one species only is known (<i>A. palpebratus</i>),
+represents the family of Horse-Mackerels in the depths of the sea; but
+we do not know, at present, at what depth it lives. Only six specimens
+have been obtained hitherto from the vicinity of Amboyna, the Fidji,
+and Paumotu Islands; the largest was twelve inches long.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Capros.</span>—Body compressed and elevated. Mouth very
+protractile. Scales rather small, spiny. First dorsal with nine
+spines, anal with three. Ventral fins well developed. Minute
+teeth in the jaws and on the vomer; none on the palatine bones.</p>
+</div>
+
+<p>The “Boar-fish” (<i>C. aper</i>) is common in the Mediterranean, and
+not rarely found on the south coast of England.</p>
+
+<p>Allied are <i>Antigonia</i> and <i>Diretmus</i>, known from a few
+individuals obtained at Madeira and Barbadoes; they are probably fishes
+which but rarely come to the surface.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Equula.</span>—Body more or less compressed, elevated or
+oblong, covered with small, deciduous, cycloid scales. Mouth
+very protractile. Minute teeth in the jaws; none on the palate.
+One dorsal. Formula of the fins: D. 8/1516, A. 3/14, V. 1/5. The
+lower præopercular margin serrated.</p>
+</div>
+
+<p><span class="pagenum" id="Page_450">[450]</span></p>
+
+  <div class="figcenter" id="fig200" style="max-width: 494px">
+     <img
+    class="p1"   
+    src="images/fig200.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 200.—Equula edentula.</p>
+  </div>
+
+<p>Small species, abundant in the Indo-Pacific, disappearing on the coasts
+of Japan and Australia. Some eighteen species have been described.</p>
+
+<p><i>Gazza</i> is very similar to <i>Equula</i>, but armed with canine
+teeth in the jaws.</p>
+
+<p>Other genera referred to this family are <i>Lactarius</i> (<i>L.
+delicatulus</i>, common, and eaten on the East Indian coasts),
+<i>Seriolella</i>, <i>Paropsis</i>, and <i>Platystethus</i>.</p>
+
+
+<h6 class="smcap">Third Family—Cyttidæ.</h6>
+
+<p><i>Body elevated, compressed, covered with small scales, or with
+bucklers, or naked; eye lateral. Teeth conical, small. No bony stay
+for the præoperculum. Dorsal fin composed of two distinct portions.
+Ventrals thoracic. No prominent papilla near the vent. Gill-opening
+wide. More than ten abdominal and more than fourteen caudal
+vertebræ.</i></p>
+
+<p>The fishes of the “Dory” family are truly marine, and inhabit the
+temperate zone of the Northern and Southern Hemispheres. Some fossils
+from tertiary formations (one from Licata) belong to the genus Zeus.</p>
+
+<p><span class="pagenum" id="Page_451">[451]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Zeus.</span>—A series of bony plates runs along the base of
+the dorsal and anal fins; another series on the abdomen. Three
+or four anal spines.</p>
+</div>
+
+<p>“John Dorys” are found in the Mediterranean, on the eastern temperate
+shores of the Atlantic, on the coasts of Japan and Australia. Six
+species are known, all of which are highly esteemed for the table. The
+English name given to one of the European species (<i>Zeus faber</i>)
+seems to be partly a corruption of the Gascon “Jau,” which signifies
+cock, “Dory” being derived from the French Dorée, so that the entire
+name means Gilt-Cock. Indeed, in some other localities of Southern
+Europe it bears the name of <i>Gallo</i>. The same species occurs also
+on the coasts of South Australia and New Zealand. The fishermen of
+Roman Catholic countries hold this fish in special respect, as they
+recognise in a black round spot on its side the mark left by the thumb
+of St. Peter when he took the piece of money from its mouth.</p>
+
+  <div class="figcenter" id="fig201" style="max-width: 434px">
+     <img
+    class="p1"   
+    src="images/fig201.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 201.—Cyttus australis.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cyttus.</span>—Body covered with very small scales; no
+osseous<span class="pagenum" id="Page_452">[452]</span> bucklers on any part of the body. Two anal spines;
+ventral fins composed of one spine and six or eight rays.</p>
+</div>
+
+<p>Three species are known from Madeira, South Australia, and New Zealand.</p>
+
+
+<h6 class="smcap">Fourth Family—Stromateidæ.</h6>
+
+<p><i>Body more or less oblong and compressed, covered with very small
+scales; eye lateral. Dentition very feeble; œsophagus armed with
+numerous horny, barbed processes. No bony stay for the præoperculum.
+Dorsal fin single, long, without distinct spinous division. More than
+ten abdominal and more than fourteen caudal vertebræ.</i></p>
+
+<p>This small family consists of strictly marine and partly
+pelagic species referred to two genera, <i>Stromateus</i> and
+<i>Centrolophus</i>. The former lacks ventral fins, at least in the
+adult stage, and is represented by about ten species in almost all the
+tropical and warmer seas. <i>Centrolophus</i>, hitherto known from two
+or three European species only (of which one occasionally reaches the
+south coast of England, where it is named “Black-fish”), has recently
+been discovered on the coast of Peru, and has probably a much wider
+range.</p>
+
+
+<h6 class="smcap">Fifth Family—Coryphænidæ.</h6>
+
+<p><i>Body compressed; eye lateral. Teeth small, conical, if present;
+œsophagus smooth. No bony stay for the præoperculum. Dorsal fin single,
+long, without distinct spinous division. More than ten abdominal and
+more than fourteen caudal vertebræ.</i></p>
+
+<p>All the members of this family have pelagic habits. Representatives
+of it have been recognized in some fossil remains: thus
+<i>Goniognathus</i> from the Isle of Sheppey, and the living genus
+<i>Mene</i> (<i>Gastrocnemus</i>) at Monte Bolca.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Coryphæna.</span>—Body compressed, rather elongate; adult
+specimens with a high crest on the top of the head; cleft of
+the mouth<span class="pagenum" id="Page_453">[453]</span> wide. A single dorsal extending from the occiput
+almost to the caudal, which is deeply forked; no distinct
+dorsal and anal spines. The ventrals are well developed, and
+can be received in a groove on the abdomen. Scales very small.
+Rasp-like teeth in the jaws, on the vomer and the palatine
+bones. Air-bladder absent.</p>
+</div>
+
+  <div class="figcenter" id="fig202" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig202.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 202.—Dolphin from the Atlantic.</p>
+  </div>
+
+<p>Generally, though by misapplication of the name, called “Dolphins.”
+About six species are known, each of which is probably distributed
+over all the tropical and sub-tropical seas. Strictly pelagic in their
+habits, they are most powerful swimmers; they congregate in shoals,
+and pursue unceasingly the Flying-Fish, which try to escape their
+enemies by long flying leaps. They attain to a length of six feet,
+and are eagerly caught by sailors on account of their well-flavoured
+flesh. The beauty of their, unfortunately fugitive, colours has ever
+been a subject of admiration. As far as the colours are capable of
+description, those of the common species (<i>C. hippurus</i>), which is
+often seen in the Mediterranean, are silvery blue above, with markings
+of a deeper azure, and reflections of pure gold, the lower parts being
+lemon-yellow, marked with pale blue. The pectoral fins are partly lead
+colour, partly yellow; the anal is yellow, the iris of the eye golden.
+These iridescent colours change rapidly whilst the fish is dying, as in
+the Mackerel. The form of the body, and especially of the head, changes
+considerably with age. Very young specimens, from one to six inches
+in length, are abundant in the open sea, and frequently obtained in
+the tow-net. Their body is cylindrical, their head as broad as high,
+and the eye relatively<span class="pagenum" id="Page_454">[454]</span> very large, much longer than the snout. As the
+fish grows the body is more compressed, and finally a high crest is
+developed on the head, and the anterior part of the dorsal fin attains
+a height equal to that of the body.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Brama.</span>—Body compressed, and more or less elevated,
+covered with rather small scales; cleft of the mouth very
+oblique, with the lower jaw longest. Dorsal and anal fins
+many-rayed, the former with three or four, the latter with two
+or three, spines; caudal deeply forked. Ventrals thoracic,
+with one spine and five rays. The jaws with an outer series of
+stronger teeth.</p>
+</div>
+
+<p>Pelagic fishes which, like the allied genus <i>Taractes</i>, range over
+almost all the tropical and temperate seas.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lampris.</span>—Body compressed and elevated, covered with
+very small deciduous scales; cleft of the mouth narrow. A single
+dorsal, without a spinous portion. Ventrals composed of numerous
+rays. Teeth none.</p>
+</div>
+
+  <div class="figcenter" id="fig203" style="max-width: 615px">
+     <img
+    class="p1"   
+    src="images/fig203.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 203.—Lampris luna.</p>
+  </div>
+
+<p>The “Sun-fish” (<i>L. luna</i>) is one of the most beautiful fishes of
+the Atlantic. It attains to the large size of four feet in length, is
+bluish on the back, with round silvery spots, which colour prevails
+on the lower parts; the fins are of a<span class="pagenum" id="Page_455">[455]</span> deep scarlet. It is said to be
+excellent eating. It is a pelagic fish, not rare about Madeira, but
+extending far northwards in the Atlantic; it seems to be rarer in the
+Mediterranean. All the specimens hitherto obtained were full-grown
+or nearly so. The skeleton exhibits several peculiarities, viz. an
+extraordinary development and dilatation of the humeral arch, and great
+strength of the numerous and closely-set ribs.</p>
+
+<p>Other Coryphænoid genera are <i>Pteraclis</i>, <i>Schedophilus</i>,
+<i>Diana</i>, <i>Ausonia</i>, and <i>Mene</i>; all pelagic forms.</p>
+
+
+<h6 class="smcap">Sixth Family—Nomeidæ.</h6>
+
+<p><i>Body oblong, more or less compressed, covered with cycloid scales of
+moderate size; eye lateral. No bony stay for the præoperculum. Dorsal
+fin with a distinct spinous portion separated from the soft; sometimes
+finlets; caudal forked. More than ten abdominal, and more than fourteen
+caudal vertebræ.</i></p>
+
+<p>Marine fishes; pelagic, at least when young.</p>
+
+  <div class="figcenter" id="fig204" style="max-width: 498px">
+     <img
+    class="p1"   
+    src="images/fig204.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 204.—Gastrochisma melampus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gastrochisma.</span>—Cleft of the mouth wide. Finlets behind
+the dorsal and anal fins. The ventral fins are exceedingly
+broad<span class="pagenum" id="Page_456">[456]</span> and long, and can be completely concealed in a fold of
+the abdomen.</p>
+</div>
+
+<p><i>G. melampus</i>, from the coast of New Zealand; scarce.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Nomeus.</span>—Cleft of the mouth narrow. No finlets. The
+ventral fin is long and broad, attached to the abdomen by a
+membrane, and can be received in a fissure of the abdomen.</p>
+</div>
+
+<p><i>N. gronovii</i> is a common pelagic fish in the Atlantic and Indian
+Oceans; of small size.</p>
+
+<p>Other genera belonging to this family are <i>Psenes</i> and
+<i>Cubiceps</i>.</p>
+
+
+<h6 class="smcap">Seventh Family—Scombridæ.</h6>
+
+<p><i>Body oblong, scarcely compressed, naked or covered with small
+scales; eye lateral. Dentition well developed. No bony stay for the
+præoperculum. Two dorsal fins; generally finlets. Ventrals thoracic,
+with one spine and five rays. More than ten abdominal, and more than
+fourteen caudal vertebræ.</i></p>
+
+<p>The fishes of the “Mackerel” family are pelagic forms, abundant in all
+the seas of the tropical and temperate zones. They are one of the four
+families of fishes which are the most useful to man, the others being
+the Gadoids, Clupeoids, and Salmonoids. They are fishes of prey, and
+unceasingly active, their power of endurance in swimming being equal
+to the rapidity of their motions. Their muscles receive a greater
+supply of blood-vessels and nerves than in other fishes, and are of a
+red colour, and more like those of birds or mammals. This energy of
+muscular action causes the temperature of their blood to be several
+degrees higher than in other fishes. They wander about in shoals, spawn
+in the open sea, but periodically approach the shore, probably in the
+pursuit of other fishes on which they feed.<a id="FNanchor_43" href="#Footnote_43" class="fnanchor">[43]</a></p>
+
+<p><span class="pagenum" id="Page_457">[457]</span></p>
+
+<p><i>Scombridæ</i> are well represented in tertiary formations: in the
+Eocene schists of Glaris two extinct genera, <i>Palimphyes</i> and
+<i>Isurus</i>, have been discovered. In Eocene and Miocene formations
+<i>Scomber</i>, <i>Thynnus</i>, and <i>Cybium</i> are not uncommon.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scomber.</span>—The first dorsal continuous, with feeble
+spines; five or six finlets behind the dorsal and anal. Scales
+very small, and equally covering the whole body. Teeth small.
+Two short ridges on each side of the caudal fin.</p>
+</div>
+
+<p>Mackerels proper are found in almost all temperate and tropical seas,
+with the exception of the Atlantic shores of temperate South America,
+where they have not been found hitherto. In Europe, and probably also
+on the coast of England, three species occur: <i>S. scomber</i>, the
+common Mackerel, which lacks an air-bladder; <i>S. pneumatophorus</i>,
+a more southern species, with an air-bladder; and <i>S. colias</i>,
+like the former, but with a somewhat different coloration, and often
+called “Spanish” Mackerel. On the Cape of Good Hope, in Japan, on the
+coast of California, in South Australia, and New Zealand, Mackerels
+are abundant, which are either identical with, or very closely allied
+to, the European species. On the coasts of the United States the
+same species occur which tenant the western parts of the Atlantic.
+Altogether seven species are known.</p>
+
+  <div class="figcenter" id="fig205" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig205.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 205.—Thynnus thynnus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Thynnus.</span>—The first dorsal continuous, with the spines
+rather feeble; from six to nine finlets behind the dorsal and
+anal.<span class="pagenum" id="Page_458">[458]</span> Scales of the pectoral region crowded, forming a corslet.
+Teeth rather small. A longitudinal keel on each side of the tail.</p>
+</div>
+
+<p>The best-known species of this genus is the “Tunny” (<i>Thynnus
+thynnus</i>), abundant in the Mediterranean, and ranging to the south
+coast of England and to Tasmania. It is one of the largest fishes of
+the ocean, attaining to a length of 10 feet, and to a weight of more
+than 1000 lbs. The fishery of the Tunny is systematically carried on in
+the Mediterranean, and dates from the most remote antiquity. Its salted
+preparation was esteemed by the Romans under the name of <i>Saltamentum
+sardicum</i>. Its flesh is extensively eaten now, fresh as well as
+preserved.</p>
+
+<p><i>Thynnus pelamys</i>, or the “Bonito,” is equally well known, and
+ranges over all the tropical and temperate seas; it eagerly pursues the
+Flying-fish, and affords welcome sport and food to the sailor. In its
+form it resembles the Tunny, but is more slender and rarely above three
+feet long.</p>
+
+<p>Some of the other species are provided with very long pectoral fins,
+and generally called by sailors “Albacore.” They are said to grow to a
+length of six feet; Bennett in his “Whaling Voyage,” vol. ii. p. 278,
+makes the following observations on <i>Th. germo</i>, from the Pacific:
+“Ships when cruising slowly in the Pacific Ocean, are usually attended
+by myriads of this fish for many successive months. A few days’ rapid
+sailing is, nevertheless, sufficient to get rid of them, however
+numerous they may be, for they seldom pay more than very transient
+visits to vessels making a quick passage. When the ship is sailing with
+a fresh breeze they swim pertinaciously by her side and take the hook
+greedily, but should she be lying motionless or becalmed they go off
+to some distance in search of prey, and cannot be prevailed upon to
+take the most tempting bait the sailor can devise. It is probably as a
+protection from their chief enemy, the Sword-fish, that they seek the
+society of a ship. I am not aware that the Shark is<span class="pagenum" id="Page_459">[459]</span> also their enemy;
+but they seemed to have an instinctive dread of this large fish, and
+when it approached the ship, would follow it in shoals, and annoy it in
+the same manner as the smaller birds may be seen to annoy those of a
+larger and predaceous kind, as the hawk or owl. They are very voracious
+and miscellaneous feeders. Flying-fish, Calmars, and small shoal-fish
+are their most natural food; though they do not refuse the animal
+offal from a ship. Amongst the other food contained in their maw, we
+have found small Ostracions, File-fish, Sucking-fish, Janthina shells,
+and pelagic crabs; in one instance a small Bonita, and in a second a
+Dolphin eight inches long, and a Paper-nautilus shell containing its
+sepia-tenant. It was often amusing to watch an Albacore pursuing a
+Flying-fish, and to mark the precision with which it swam beneath the
+feeble æronaut, keeping him steadily in view, and preparing to seize
+him at the moment of his descent. But this the Flying-fish would often
+elude by instantaneously renewing his leap, and not unfrequently escape
+by extreme agility.”</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pelamys.</span>—The first dorsal continuous, with the spines
+rather feeble; from seven to nine finlets behind the dorsal and
+anal. Scales of the pectoral region forming a corslet. Teeth
+moderately strong. A longitudinal keel on each side of the tail.</p>
+</div>
+
+<p>Five species are known, of which <i>P. sarda</i> is common in the
+Atlantic and Mediterranean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Auxis.</span>—Differing from the preceding two genera in
+having very small teeth in the jaws only, none on the palate.</p>
+</div>
+
+<p><i>Auxis rochei</i> common in the Atlantic, Mediterranean, and Indian
+Ocean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cybium.</span>—The first dorsal continuous, with the spines
+rather feeble; generally more than seven finlets behind the
+dorsal and anal. Scales rudimentary or absent. Teeth strong; a
+longitudinal keel on each side of the tail.</p>
+</div>
+
+<p>Twelve species from the tropical Atlantic and Indian<span class="pagenum" id="Page_460">[460]</span> Ocean;
+frequenting more the coast-region than the open sea; attaining to a
+length of four or five feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Elacate.</span>—Body covered with very small scales; head
+depressed; cleft of the mouth moderately wide; no keel on the
+tail. The spinous dorsal is formed by eight small free spines;
+finlets none. Villiform teeth in the jaws, on the vomer and the
+palatine bones.</p>
+</div>
+
+<p><i>Elacate nigra</i>, a coast fish common in the warmer parts of the
+Atlantic and the Indian Ocean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Echeneis.</span>—The spinous dorsal fin is modified into an
+adhesive disk, occupying the upper side of the head and neck.</p>
+</div>
+
+<p>This genus is closely allied to the preceding, from which it differs
+only by the transformation of the spinous dorsal fin into a sucking
+organ. The spines being composed of two halves, each half is bent down
+towards the right and the left, forming a support to a double series of
+transverse lamellæ, rough on their edges, the whole disk being of an
+oval shape and surrounded by a membranous fringe. Each pair of lamellæ
+is formed out of one spine, which, as usual, is supported at the base
+by an interneural spine. By means of this disk the “Sucking-fishes”
+or “Suckers” are enabled to attach themselves to any flat surface,
+a series of vacuums being created by the erection of the usually
+recumbent lamellæ. The adhesion is so strong that the fish can only be
+dislodged with difficulty, unless it is pushed forward by a sliding
+motion. The Suckers attach themselves to sharks, turtles, ships, or any
+other object which serves their purpose. They cannot be regarded as
+parasites, inasmuch as they obtain their food independently of their
+host. Being bad swimmers they allow themselves to be carried about by
+other animals or vessels endowed with a greater power of locomotion.
+They were as well known to the ancients as they are to the modern
+navigators. Aristotle and Aelian mention the Sucker under the name of
+φθεὶρ, or the <i>Louse</i>; “In the sea<span class="pagenum" id="Page_461">[461]</span> between Cyrene and Egypt there
+is a fish about the Dolphin (<i>Delphinus</i>), which they call the
+Louse; this becomes the fattest of all fishes, because it partakes of
+the plentiful supply of food captured by the Dolphin.” Later writers,
+then, repeat a story, the source of which is unknown, viz. that the
+“Remora” is able to arrest vessels in their course, a story which has
+been handed down to our own time. It need not be stated that this is an
+invention, though it cannot be denied that the attachment of one of the
+larger species may retard the progress of a sailing vessel, especially
+when, as is sometimes the case, several individuals accompany the same
+ship. An account of a somewhat ingenious way of catching sleeping
+turtles by means of a Sucking-fish held by a ring fastened round its
+tail, appears to have originated rather from an experiment than from
+regular practice.</p>
+
+<p>Ten different species are known, of which <i>Echeneis remora</i> and
+<i>Echeneis naucrates</i> are the most common. The former is short
+and grows to a length of eight inches only, the latter is a slender
+fish, not rarely found three feet long. The bulkiest is <i>Echeneis
+scutata</i>, which attains to a length of two feet; individuals of that
+size weighing about eight lbs.</p>
+
+<p>The number of pairs of lamellæ varies in the various species, from 12
+to 27. The caudal fin of some of the species undergoes great changes
+with age. In young specimens the middle portion of the fin is produced
+into a long filiform lobe. This lobe becomes gradually shorter, and the
+fin shows a rounded margin in individuals of middle age. When the fish
+approaches the mature state, the upper and lower lobes are produced,
+and the fin becomes subcrescentic or forked.</p>
+
+<div class="blockquot">
+
+<p>[See Günther, “On the History of Echeneis.” Ann. and Mag. Nat.
+Hist., 1860.]</p>
+</div>
+
+<p><span class="pagenum" id="Page_462">[462]</span></p>
+
+
+<h6 class="smcap">Eighth Family.—Trachinidæ.</h6>
+
+<p><i>Body elongate, low, naked or covered with scales. Teeth small,
+conical. No bony stay for the præoperculum. One or two dorsal fins,
+the spinous portion being always shorter and much less developed than
+the soft; the anal similarly developed as the soft dorsal; no finlets.
+Ventrals with one spine and five rays. Gill-opening more or less
+wide. Ten or more than ten abdominal, and more than fourteen caudal
+vertebræ.</i></p>
+
+<p>Carnivorous coast-fishes of small size, found in every quarter of the
+globe, but scarcely represented in the Arctic zone (<i>Trichodon</i>);
+on the other hand, they are rather numerous towards the Antarctic
+circle. All are bad swimmers, generally moving along the bottom in
+small depths. Only one genus (<i>Bathydraco</i>) is known from the
+deep-sea.</p>
+
+<p>A genus which shows the principal characters of this family
+(<i>Callipteryx</i>), has been found in the tertiary deposits of Monte
+Bolca; it is scaleless. A second genus, <i>Trachinopsis</i>, has been
+recently described by Sauvage from the Upper Tertiary of Lorca in
+Spain; and a third (<i>Pseudoeleginus</i>) from the Miocene of Licata.</p>
+
+<p>This family may be subdivided into five groups:—</p>
+
+<div class="blockquot">
+
+<p>1. In the <span class="smcap">Uranoscopina</span> the eyes are on the upper
+surface of the head, directed upwards; the lateral line is
+continuous.</p>
+
+<p><span class="smcap">Uranoscopus.</span>—Head large, broad, thick, partly covered
+with bony plates; cleft of the mouth vertical. Scales very
+small. Two dorsal fins, the first with from three to five
+spines; ventrals jugular; pectoral rays branched. Villiform
+teeth in the jaws, on the vomer and palatine bones; no canines.
+Generally a long filament below and before the tongue.
+Gill-cover armed.</p>
+</div>
+
+<p>The position of the eyes on the upper surface of the head, which these
+fishes have in common with many others, is well expressed by the name
+<i>Uranoscopus</i> (Stare-gazer). Their eyes are very small, and can be
+raised or depressed at the will of<span class="pagenum" id="Page_463">[463]</span> the fish. They are inactive fishes,
+generally lying hidden at the bottom between stones, watching for their
+prey. The delicate filament attached to the bottom of their mouth, and
+playing in front of it in the current of water which passes through the
+mouth, serves to lure small animals within reach of the fish. Eleven
+species are known from the Indo-Pacific and Atlantic, and one (<i>U.
+scaber</i>) from the Mediterranean; they attain rarely a length of
+twelve inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Leptoscopus.</span>—Form of the head as in
+<i>Uranoscopus</i>, but entirely covered with a thin skin.
+Scales small, cycloid. One continuous dorsal; ventrals jugular;
+pectoral rays branched. Villiform teeth in both jaws, on the
+vomer and palatine bones; canines none. No oral filament.
+Gill-cover unarmed.</p>
+</div>
+
+  <div class="figcenter" id="fig206" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig206.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 206.—Leptoscopus macropygus.</p>
+  </div>
+
+<p><i>Leptoscopus macropygus</i>, not rare on the coast of New Zealand.</p>
+
+<p>Other genera of Stare-gazers are <i>Agnus</i> from the Atlantic coasts
+of North America; <i>Anema</i> from the Indian Ocean and New Zealand;
+and <i>Kathetostoma</i> from Australia and New Zealand.</p>
+
+<div class="blockquot">
+
+<p>2. In the <span class="smcap">Trachinina</span> the eyes are more or less lateral;
+the lateral line is continuous; and the intermaxillary without a
+larger tooth on its posterior portion.</p>
+
+<p><span class="smcap">Trachinus.</span>—Cleft of the mouth very oblique; eye
+lateral, but directed upwards. Scales very small, cycloid. Two
+dorsal fins, the first short, with six or seven spines; ventrals
+jugular; the lower pectoral rays simple. Villiform teeth in
+the jaws, on the vomer and palatine bones. Præorbital and
+præoperculum armed.</p>
+</div>
+
+<p><span class="pagenum" id="Page_464">[464]</span></p>
+
+<p>The “Weevers” are common fishes on the European coasts, and but too
+well known to all fishermen; singularly enough they do not extend
+across the Atlantic to the American coast, but reappear on the coast of
+Chili! Wounds by their dorsal and opercular spines are much dreaded,
+being extremely painful, and sometimes causing violent inflammation
+of the wounded part. No special poison-organ has been found in these
+fishes, but there is no doubt that the mucous secretion in the vicinity
+of the spines has poisonous properties. The dorsal spines as well as
+the opercular spine have a deep double groove in which the poisonous
+fluid is lodged, and by which it is inoculated in the punctured wound.
+On the British coasts two species occur, <i>T. draco</i>, the Greater
+Weever, attaining to a length of twelve inches, and <i>T. vipera</i>,
+the Lesser Weever, which grows only to half that size.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Champsodon.</span>—Body covered with minute granular scales;
+lateral lines two, with numerous vertical branches. Cleft of
+the mouth wide, oblique. Eye lateral, but directed upwards.
+Two dorsal fins; ventral fins jugular; pectoral rays branched.
+Teeth in the jaws in a single series, thin, long, of unequal
+size. Teeth on the vomer, none on the palate. Gill-openings
+exceedingly wide. Præoperculum with a spine at the angle and a
+fine serrature on the posterior margin.</p>
+</div>
+
+<p><i>Champsodon vorax</i> is not uncommon at small depths off the
+Philippine Islands, Admiralty Islands, and in the Arafura Sea.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Percis.</span>—Body cylindrical, with small ctenoid scales;
+cleft of the mouth slightly oblique; eye lateral, but directed
+upwards. Dorsal fins more or less continuous, the spinous with
+four or five short stiff spines; ventrals a little before the
+pectorals. Villiform teeth in the jaws, with the addition of
+canines; teeth on the vomer, none on the palatines. Opercles
+feebly armed.</p>
+</div>
+
+<p>Fifteen species; small, but prettily coloured shore-fishes of the
+Indo-Pacific.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sillago.</span>—Body covered with rather small, ctenoid
+scales.<span class="pagenum" id="Page_465">[465]</span> Cleft of the mouth small, with the upper jaw rather
+longer; eye lateral, large. Two dorsals, the first with from
+nine to twelve spines; ventrals thoracic. Villiform teeth in the
+jaws, and on the vomer, none on the palatine bones. Operculum
+unarmed; præoperculum serrated. The bones of the head with wide
+muciferous channels.</p>
+</div>
+
+<p>Eight species; small, plain-coloured shore-fishes, common in the Indian
+Ocean to the coasts of Australia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bovichthys.</span>—Head broad and thick; cleft of the mouth
+horizontal, with the upper jaw rather longer; eye lateral, more
+or less directed upwards. Scales none. Two separate dorsal
+fins, the first with eight spines; ventrals jugular; the lower
+pectoral rays simple. Villiform teeth in the jaws, on the vomer
+and the palatine bones; no canines. Operculum with a strong
+spine; præorbital and præoperculum not armed.</p>
+</div>
+
+<p>Three species are known from the South Pacific.</p>
+
+  <div class="figcenter" id="fig207" style="max-width: 361px">
+     <img
+    class="p1"   
+    src="images/fig207.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 207.—Head of Bovichthys variegatus, from New Zealand.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bathydraco.</span>—Body elongate, sub-cylindrical; head
+depressed, with the snout much elongate, spatulate; mouth wide,
+horizontal, with the lower jaw prominent; eyes very large,
+lateral, close together. Scales very small, imbedded in the
+skin. Lateral line wide, continuous. One dorsal fin; ventrals
+jugular; the<span class="pagenum" id="Page_466">[466]</span> lower pectoral rays branched. Teeth in the jaws
+in villiform bands; none on the vomer or the palatine bones.
+Opercles unarmed; ten branchiostegals; the gill-membranes free
+from the isthmus, and but slightly united in front. Air-bladder
+none.</p>
+</div>
+
+<p>A deep-sea fish, found at a depth of 1260 fathoms in the Antarctic
+Ocean (south of Heard Island).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chænichthys.</span>—Head very large, with the snout
+spatulate, and with the cleft of the mouth very wide. Eye
+lateral. Scales none; lateral line sometimes with granulated
+scutes. Two dorsals, the first with seven spines; ventrals
+jugular. Jaws with rasp-like teeth; palate toothless.</p>
+</div>
+
+<p><i>Chænichthys rhinoceratus</i> from Kerguelen’s Land (see Fig. <a href="#fig108">108</a>, p.
+291); and <i>Ch. esox</i> from the Straits of Magelhaen.</p>
+
+<p>Other genera belonging to this group are <i>Aphritis</i>,
+<i>Acanthaphritis</i>, <i>Eleginus</i>, <i>Chænichthys</i>, and
+<i>Chimarrhichthys</i> from the South Pacific and Antarctic zone;
+<i>Cottoperca</i> from the west coast of Patagonia; <i>Percophis</i>
+from the coast of Southern Brazil; and <i>Trichodon</i> from the coast
+of Kamtschatka.</p>
+
+<div class="blockquot">
+
+<p>3. In the <span class="smcap">Pinguipedina</span> the body is covered with small
+scales; the eye lateral; the lateral line continuous; and the
+intermaxillary is armed with a larger tooth on its posterior
+portion, as in many Labroids.</p>
+</div>
+
+<p>Two genera, <i>Pinguipes</i> and <i>Latilus</i>, from various parts of
+tropical and sub-tropical seas, belong to this group.</p>
+
+<div class="blockquot">
+
+<p>4. In the <span class="smcap">Pseudochromides</span>, the lateral line is
+interrupted or not continued to the caudal fin; they have one
+continuous dorsal only.</p>
+</div>
+
+<p>These fishes are inhabitants of coral reefs or coasts:
+<i>Opisthognathus</i>, <i>Pseudochromis</i>, <i>Cichlops</i>, and
+<i>Pseudoplesiops</i>.</p>
+
+<div class="blockquot">
+
+<p>5. In the <span class="smcap">Nototheniina</span> the lateral line is interrupted;
+and the dorsal fin consists of two separate portions.</p>
+</div>
+
+<p>They (with others) represent in the Antarctic zone the Cottoids of
+the Northern Hemisphere: they have the same habits as their northern
+analogues. In <i>Notothenia</i>, which on<span class="pagenum" id="Page_467">[467]</span> the southern extremity of
+South America, in New Zealand, Kerguelen’s Land, etc., is represented
+by about twenty species, the body is covered with ctenoid scales, and
+the bones of the head are unarmed; whilst <i>Harpagifer</i>, a small
+species with a similar range as <i>Notothenia</i>, has the body naked,
+and the operculum and sub-operculum armed with long and strong spines.</p>
+
+
+<h6 class="smcap">Ninth Family—Malacanthidæ.</h6>
+
+<p><i>Body elongate, with very small scales; mouth with thick lips; a
+strong tooth posteriorly on the intermaxillary. Dorsal and anal fins
+very long, the former with a few simple rays anteriorly; ventrals
+thoracic, with one spine and five rays. Gill-opening wide, with the
+gill-membranes united below the throat. Ten abdominal and fourteen
+caudal vertebræ.</i></p>
+
+<p>One genus only, <i>Malacanthus</i>, with three species from tropical
+seas.</p>
+
+
+<h6 class="smcap">Tenth Family—Batrachidæ.</h6>
+
+<p><i>Head broad and thick; body elongate, compressed behind; skin naked
+or with small scales. No bony stay for the præoperculum. Teeth conical,
+small or of moderate size. The spinous dorsal consists of two or three
+spines only; the soft and the anal long. Ventrals jugular, with two
+soft rays; pectorals not pediculated. Gill-opening a more or less
+vertical slit before the pectoral, rather narrow.</i></p>
+
+<p>Carnivorous fishes, of small size, living on the bottom of the sea near
+the coast in the tropical zone, some species advancing into the warmer
+parts of the temperate zones.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Batrachus.</span>—The spinous dorsal is formed by three stout
+spines. Gill-covers armed with spines. Circumference of the
+mouth and other parts of the head frequently provided with small
+skinny tentacles.</p>
+</div>
+
+<p>Some of the fishes of this genus possess a subcutaneous<span class="pagenum" id="Page_468">[468]</span> spacious
+cavity behind the base of the pectoral fin, the inside of which is
+coated with a reticulated mucous membrane. It opens by a foramen in
+the upper part of the axil.—This apparatus is the same which is found
+in many Siluroid fishes, and which has been noticed above, p. 192.
+There cannot be any doubt that it is a secretory organ, but whether
+the secretion has any poisonous properties, as in the Siluroids, or
+as in <i>Thalassophryne</i>, has not been determined. No instance of
+poisonous wounds having been inflicted by these fishes is on record.
+Twelve species are known, the distribution of which coincides with that
+of the family; one very fine species, <i>B. didactylus</i>, occurs in
+the Mediterranean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Thalassophryne.</span>—The spinous dorsal is formed by two
+spines only, each of which is hollow, like the opercular spine,
+and conveys the contents of a poison-bag situated at its base.
+Canine teeth none.</p>
+</div>
+
+  <div class="figcenter" id="fig208" style="max-width: 598px">
+     <img
+    class="p1"   
+    src="images/fig208.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 208.—Thalassophryne reticulata.</p>
+  </div>
+
+<p>Two species are known from the Atlantic and Pacific coasts of Central
+America. The poison-apparatus is more perfectly developed than any
+other known at present in the class of fishes; it has been described
+above, p. 192. The species figured, <i>Th. reticulata</i>, is not
+uncommon at Panama, and attains to a length of fifteen inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Porichthys.</span>—Two small dorsal spines; a canine tooth on
+each side of the vomer.</p>
+</div>
+
+<p>Two species, from the Atlantic and Pacific sides of Central and South
+America.</p>
+
+<p><span class="pagenum" id="Page_469">[469]</span></p>
+
+
+<h6 class="smcap">Eleventh Family—Psychrolutidæ.</h6>
+
+<p><i>Body rather elongate, naked; head broad. Spinous dorsal separate or
+absent. Ventral fins close together, thoracic, composed of a few rays.
+Teeth small. Three gills and a half; pseudobranchiæ well developed;
+gill-openings of moderate width, the gill-membranes being attached to
+the isthmus.</i></p>
+
+<p>Of this family only two representatives are known, viz. <i>Psychrolutes
+paradoxus</i>, from Vancouver’s Islands, without first dorsal fin; and
+<i>Neophrynichthys latus</i>, from New Zealand, with two dorsal fins.
+Both are very scarce marine fishes.</p>
+
+
+<h6 class="smcap">Twelfth Family—Pediculati.</h6>
+
+<p><i>Head and anterior part of the body very large, without scales. No
+bony stay for the præoperculum. Teeth villiform or rasp-like. The
+spinous dorsal is advanced forwards, composed of a few more or less
+isolated spines, often transformed into tentacles; or entirely absent.
+Ventral fins jugular, with four or five soft rays, sometimes absent.
+The carpal bones are prolonged, forming a sort of arm, terminating in
+the pectoral. Gill-opening reduced to a small foramen, situated in or
+near the axil. Gills two and a half, or three, or three and a half;
+pseudobranchiæ generally absent.</i></p>
+
+<p>This family contains a larger number of bizarre forms than any other;
+and there is, perhaps, none in which the singular organisation of the
+fish is more distinctly seen to be in consonance with its habits.
+Pediculates are found in all seas. The habits of all are equally
+sluggish and inactive; they are very bad swimmers; those found near the
+coasts lie on the bottom of the sea, holding on with their arm-like
+pectoral fins by seaweed or stones, between which they are hidden;
+those of pelagic habits attach themselves to floating seaweed or
+other objects, and are at the mercy of wind and current. A<span class="pagenum" id="Page_470">[470]</span> large
+proportion of the genera, therefore, have gradually found their way to
+the greatest depths of the ocean; retaining all the characteristics of
+their surface-ancestors, but assuming the modifications by which they
+are enabled to live in abyssal depths.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lophius.</span>—Head exceedingly large, broad, depressed,
+with the eyes on its upper surface; cleft of the mouth very
+wide. Jaws and palate armed with rasp-like depressible teeth of
+unequal size. Body naked; bones of the head armed with numerous
+spines. The three anterior dorsal spines are isolated, situated
+on the head, and modified into long tentacles; the three
+following spines form a continuous fin; the soft dorsal and anal
+short. Gills three. Young individuals have the tentacles beset
+with lappets, and most of the fin-rays prolonged into filaments.</p>
+</div>
+
+<p>These fishes are well known under the names “Fishing-Frog,”
+“Frog-fishes,” “Anglers,” or “Sea-devils.” They are coast-fishes,
+living at very small depths. Four species are known: the British
+species (<i>L. piscatorius</i>) found all round the coasts of Europe
+and Western North America, and on the Cape of Good Hope; a second
+(Mediterranean) species, <i>L. budegassa</i>; <i>L. setigerus</i> from
+China and Japan; and <i>L. naresii</i> from the Admiralty Islands.</p>
+
+  <div class="figcenter" id="fig209" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig209.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 209.—Lophius piscatorius.</p>
+  </div>
+
+  <div class="figcenter" id="fig210" style="max-width: 391px">
+     <img
+    class="p1"   
+    src="images/fig210.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 210.—A young Fishing-Frog.</p>
+  </div>
+
+<p>The habits of all these species are identical. The wide<span class="pagenum" id="Page_471">[471]</span> mouth
+extends all round the anterior circumference of the head, and both
+jaws are armed with bands of long pointed teeth, which are inclined
+inwards, and can be depressed so as to offer no impediment to an
+object gliding towards the stomach, but prevent its escape from the
+mouth. The pectoral and ventral fins are so articulated as to perform
+the functions of teeth, the fish being enabled to move, or rather to
+walk, on the bottom of the sea, where it generally hides itself in
+the sand, or amongst seaweed. All round its head, and also along the
+body, the skin bears fringed appendages, resembling short fronds of
+seaweed; a structure which, combined with the extraordinary faculty of
+assimilating the colours of the body to its surroundings, assists this
+fish greatly in concealing itself in places which it selects on account
+of the abundance of prey. To render the organisation of these creatures
+perfect in relation to their wants, they<span class="pagenum" id="Page_472">[472]</span> are provided with three long
+filaments inserted along the middle of the head, which are, in fact,
+the detached and modified three first spines of the anterior dorsal
+fin. The filaments most important in the economy of the fishing-frogs
+is the first, which is the longest, terminates in a lappet, and is
+movable in every direction. There is no doubt that the Fishing-frog,
+like many other fish provided with similar appendages, plays with this
+filament as with a bait, attracting fishes, which, when sufficiently
+near, are ingulfed by the simple act of the Fishing-frog opening its
+gape. Its stomach is distensible in an extraordinary degree, and not
+rarely fishes have been taken out of it quite as large and heavy as
+their destroyer. The British species grows to a length of more than
+five feet; specimens of three feet are common. Baird records that the
+spawn of the same species has been observed as a floating sheet of
+mucus, of from some 60 to 100 square feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ceratias.</span>—Head and body much compressed and elevated;
+cleft of the mouth wide, subvertical. Eyes very small. Teeth in
+the jaws rasp-like, depressible; palate toothless. Skin covered
+with numerous prickles. The spinous dorsal is reduced to two
+long isolated spines, the first on the middle of the head, the
+second on the back. The soft dorsal and anal short; caudal very
+long. Ventrals none; pectorals very short. Two and a half gills.
+Skeleton soft and fibrous.</p>
+</div>
+
+<p><i>Ceratias holbölli</i>, a deep-sea fish; only a few examples have
+been found near the coast of Greenland, and from the mid-Atlantic; the
+latter at a depth of 2400 fathoms. Deep black.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Himantolophus.</span>—Head and body compressed and elevated;
+cleft of the mouth wide, oblique. Eyes very small. Teeth of
+the jaws rasp-like, depressible; palate toothless. Skin with
+scattered conical tubercles. The spinous dorsal is reduced to a
+single tentacle on the head. The soft dorsal, anal, caudal, and
+pectoral short. Ventrals none. Three and a half gills. Skeleton
+soft and fibrous.</p>
+</div>
+
+<p><span class="pagenum" id="Page_473">[473]</span></p>
+
+<p>This is another deep-sea form, hitherto found in very few examples in
+the Arctic and Mid-Atlantic Oceans. The single tentacle is beset with
+many long filaments at its extremity, thus answering the same purpose
+which is attained by a greater number of tentacles. Deep black.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Melanocetus.</span>—Head and body compressed; head very
+large; cleft of the mouth exceedingly wide, vertical. Eyes very
+small. Teeth of the jaws and vomer rasp-like, depressible. Skin
+smooth. The spinous dorsal is reduced to a single filament
+placed on the head. The soft dorsal and anal short. Ventrals
+none.</p>
+</div>
+
+  <div class="figcenter" id="fig211" style="max-width: 434px">
+     <img
+    class="p1"   
+    src="images/fig211.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 211.—Melanocetus johnsonii.</p>
+  </div>
+
+<p>Two species are known from the Atlantic: <i>M. bispinossus</i> and
+<i>M. johnsonii</i>, obtained at depths of from 360 to 1800 fathoms.
+The specimen figured was not quite four inches long, and contained in
+its stomach, rolled up spirally into a ball, a Scopeline fish which
+measured 7½ inches in length and one inch in depth.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Oneirodes.</span>—A deep-sea fish from the Arctic Ocean,
+differing from the preceding in possessing a second isolated
+dorsal ray on the back.</p>
+
+<p><span class="smcap">Antennarius.</span>—Head very large, high, compressed; cleft
+of the mouth vertical or subvertical, of moderate width. Jaws
+and palate armed with rasp-like teeth. Eye small. Body naked<span class="pagenum" id="Page_474">[474]</span>
+or covered with minute spines; generally with tentacles. The
+spinous dorsal is reduced to three isolated spines, the anterior
+of which is modified into a tentacle, situated above the snout.
+The soft dorsal of moderate length; anal short. Ventrals present.</p>
+</div>
+
+<p>The fishes of this genus are pelagic, frequently met with in mid-ocean
+between the tropics, especially in parts of the sea with floating
+vegetation; not rarely individuals are found far from their native
+latitudes, carried by currents to the coasts of Norway and New Zealand.
+Their power of swimming is most imperfect. When near the coast they
+conceal themselves between corals, stones, or fucus, holding on to the
+ground by means of their arm-like pectoral fins. Their coloration is so
+similar to their surroundings that it is hardly possible to distinguish
+the fish from a stone or coral overgrown with vegetation. Their way of
+attracting and seizing their prey is evidently the same as in the other
+fishes of this family. The extraordinary range of some of the species
+which inhabit the Atlantic as well as the Indo-Pacific Oceans, is the
+consequence of their habit of attaching themselves to floating objects.
+Almost all the species are highly coloured, but the pattern of the
+various colours varies exceedingly. These fishes do not attain to any
+considerable size, and probably never exceed a length of ten inches. A
+great number of species have been distinguished by ichthyologists, but
+probably not more than twenty are known at present. The species figured
+on p. 295 (<i>A. caudomaculatus</i>) is common in the Red Sea, and
+probably occurs in other parts of the Indian Ocean.</p>
+
+<p><i>Brachionichthys</i> and <i>Saccarius</i> are allied genera from
+South Australia, Tasmania, and New Zealand.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chaunax.</span>—Head very large, depressed; cleft of the
+mouth wide, subvertical; eye small; rasp-like teeth in the jaws
+and palate. Skin covered with minute spines. The spinous dorsal<span class="pagenum" id="Page_475">[475]</span>
+is reduced to a small tentacle above the snout; the soft dorsal
+of moderate length; anal short; ventrals present.</p>
+</div>
+
+<p>A deep-sea fish (<i>Ch. pictus</i>), of uniform pink colour; hitherto
+found near Madeira and the Fidji Islands, at a depth of 215 fathoms.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Malthe.</span>—Anterior portion of the body very broad
+and depressed. The anterior part of the snout is produced
+into a more or less prominent process, beneath which there
+is a tentacle retractile into a cavity. Jaws and palate with
+villiform teeth. Skin with numerous conical protuberances. Soft
+dorsal fin and anal very short. Gill-opening superiorly in the
+axil; gills two and a half.</p>
+</div>
+
+<p>Although the rostral tentacle is situated at the lower side of the
+projection of the snout, it must be regarded as the homologue of a
+dorsal spine. In some of the preceding genera, <i>Oneirodes</i> and
+<i>Chaunax</i>, the first dorsal spine is so far advanced on the snout
+as to come into connection with the intermaxillary processes; and the
+position of the rostral tentacle in <i>Malthe</i> is only a still more
+advanced step towards the same special purpose for which the first
+dorsal spine is used in this family, viz. for the purpose of obtaining
+food. In <i>Malthe</i> it is obviously an organ of touch. This genus
+belongs to the American shores of the Atlantic; <i>M. vespertilio</i>
+being a tropical, <i>M. cubifrons</i> a northern species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Halieutæa.</span>—Head exceedingly large, depressed, nearly
+circular in its circumference. Cleft of the mouth wide,
+horizontal. Jaws with small rasp-like teeth; palate smooth.
+Forehead with a transverse bony bridge, beneath which is a
+tentacle (rostral spine) retractile into a cavity. Body and head
+covered with small stellate spines. Soft dorsal and anal very
+short. Gill-opening superiorly in the axil; gills two and a half.</p>
+</div>
+
+<p>A coast-fish (<i>H. stellata</i>) from China and Japan. Frequently
+found dry in Chinese insect-boxes.</p>
+
+<p>This genus appears to be represented in the Atlantic Ocean by
+<i>Halieutichthys</i> from Cuba, and by <i>Dibranchus</i>,<span class="pagenum" id="Page_476">[476]</span> dredged at
+a depth of 360 fathoms off the coast of West Africa; the latter genus
+possesses two gills only. Another genus, covered with large scattered
+tubercles, <i>Aegæonichthys</i>, has recently been described from New
+Zealand.</p>
+
+
+<h6 class="smcap">Thirteenth Family—Cottidæ.</h6>
+
+<p><i>Form of the body oblong, sub-cylindrical. Cleft of the mouth
+lateral. Dentition feeble, generally in villiform bands. Some bones
+of the head are armed; and a bony stay connects the præopercular
+spine with the infraorbital ring. Two dorsal fins (rarely one), the
+spinous being less developed than the soft and than the anal. Ventrals
+thoracic, with five or less soft rays.</i></p>
+
+<p>The fishes of this family are of small size, bad swimmers, and
+generally living on the bottom, near the coasts, of almost all the
+arctic, temperate, and tropical seas. Only a few live in fresh water.
+They prefer shallow to deep water; and there is only one instance known
+of a member of this family living at a great depth, viz. <i>Cottus
+bathybius</i> from the Japanese sea, which is stated to have been
+dredged in a depth of 565 fathoms. Fossil representatives are few
+in number: two or three species of <i>Trigla</i>; others, although
+having a general resemblance to the genus <i>Cottus</i>, were covered
+with ctenoid scales, and therefore are referred to a distinct genus,
+<i>Lepidocottus</i>; they are from tertiary formations.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cottus.</span>—Head broad, depressed, rounded in front; body
+sub-cylindrical, compressed posteriorly. Scaleless; lateral line
+present. Pectoral rounded, with some or all the rays simple.
+Jaws and vomer with villiform teeth; palatine teeth none.</p>
+</div>
+
+<p>The “Bull-heads” or “Miller’s Thumbs” are small fishes from the shores
+and fresh waters of the northern temperate zone. Some forty species are
+known; the greater number<span class="pagenum" id="Page_477">[477]</span> live in the northern half of the temperate
+zone. On the shore, as well as in rivers, they prefer rocky or stony
+to muddy ground, lying concealed between the stones, and watching for
+their prey, which consists of small crustaceans and other aquatic
+animals. The common British Miller’s Thumb (<i>C. gobio</i>) is found
+in almost all suitable fresh waters of Northern and Central Europe,
+especially in small streams, and extends into Northern Asia. Other
+freshwater species abound in North America and Northern Asia. <i>Cottus
+scorpius</i> and <i>C. bubalis</i>, the common European marine species,
+range across the Atlantic to the American coasts. The male is said
+to construct a nest, for the reception of the spawn, of seaweeds and
+stones, and to anxiously watch and defend his offspring. The spine at
+the angle of the præoperculum, which is simple in the majority of the
+freshwater species, is frequently armed with accessory processes, and
+antler-like, in marine.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cantridermichthys</span> differs from <i>Cottus</i> in having
+teeth on the palatine bones.</p>
+</div>
+
+<p>Eleven species are known, distributed like <i>Cottus</i>, but absent in
+Europe and North-western Asia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Icelus.</span>—Head large, armed at the gill-covers and on
+the neck; body with a dorsal series of bony plates from the neck
+to the base of the caudal; lateral line with osseous tubercles;
+scattered scales on the sides and abdomen. Ventrals thoracic,
+with less than five rays. No pectoral filaments. Villiform teeth
+in the jaws, on the vomer and palatine bones.</p>
+</div>
+
+<p>Represents Cottus in the far north; <i>I. hamatus</i> is common in
+Spitzbergen and Greenland, and has been found in abundance in lat. 81°
+44’.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Platycephalus.</span>—Head broad, much depressed, more
+or less armed with spines; body depressed behind the head,
+sub-cylindrical towards the tail, covered with ctenoid scales.
+Two dorsal fins; the first spine isolated from the others.
+Ventrals<span class="pagenum" id="Page_478">[478]</span> thoracic, but rather remote from the base of the
+pectorals. Villiform teeth in the jaws, on the vomer and
+palatine bones.</p>
+</div>
+
+  <div class="figcenter" id="fig212" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig212.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 212.—Platycephalus cirrhonasus, from Port Jackson.</p>
+  </div>
+
+<p>About forty species are known, of which some attain a length of
+two feet. This genus represents in the tropical Indian Ocean the
+<i>Cotti</i> of the Arctic, and the <i>Nototheniæ</i> of the Antarctic
+zone. Like these, they live on the bottom in shallow water, hidden
+in the sand, the colours of which are assimilated by those of their
+body. Therefore, they are very scarce near coral islands which are
+surrounded by great depths; whilst the number of species is rather
+considerable on many points of the shelving Australian coasts. Their
+long and strong ventral fins are of great use to them in locomotion.
+<i>P. insidiator</i> is one of the most common Indian and Australian
+fishes, and readily recognised by two oblique black bands on the upper
+and lower caudal lobes.</p>
+
+  <div class="figcenter" id="fig213" style="max-width: 331px">
+     <img
+    class="p1"   
+    src="images/fig213.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 213.—Scale from the lateral line of the same fish.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hoplichthys</span>, similar to <i>Platycephalus</i>, but with
+the back and sides of the body covered with bony spiny plates.
+No separate dorsal spine.</p>
+</div>
+
+<p>One species, <i>H. langsdorffii</i>, is common on the coast of Japan,
+and frequently placed dry by the Chinese into their insect-boxes.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Trigla.</span>—Head parallelopiped, with the upper surface
+and the sides entirely bony, the enlarged infraorbital covering
+the cheek.</p>
+</div>
+
+<p><span class="pagenum" id="Page_479">[479]</span></p>
+
+<p>Two dorsal fins. Three free pectoral rays. Villiform teeth. Air-bladder
+generally with lateral muscles, often divided into two lateral halves.
+The species may be referred to three groups:—</p>
+
+<div class="blockquot">
+
+<p>1. Palatine teeth none; scales exceedingly small, except those
+of the lateral line: <i>Trigla</i>.</p>
+
+<p>2. Palatine teeth none; scales of moderate size:
+<i>Lepidotrigla</i>.</p>
+
+<p>3. Palatine teeth present: <i>Prionotus</i>.</p>
+</div>
+
+  <div class="figcenter" id="fig214" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig214.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 214.—Trigla pleuracanthica.</p>
+  </div>
+
+  <div class="figcenter" id="fig215" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig215.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 215.—Scute of the lateral line of the same fish.</p>
+  </div>
+
+<p>About forty species of “Gurnards” are known from tropical and temperate
+zones. They are too well known to need detailed description; one of
+their principal characteristics is the three free finger-like pectoral
+appendages, which serve as organs of locomotion as well as touch, and
+which are supplied with strong nerves, as noticed above (pp. 108 and
+120). The fins are frequently beautifully ornamented, especially the
+inner side of the long and broad pectorals, which is most exposed to
+the light when the fish is floating on the surface of the water, with
+pectorals spread out like wings. The grunting noise made by Gurnards
+when taken out of the water is caused by the escape of gas from the
+air-bladder through the open pneumatic duct. Gurnards are<span class="pagenum" id="Page_480">[480]</span> generally
+used as food; seven species occur on the British coast: the Red
+Gurnard (<i>T. pini</i>), the Streaked Gurnard (<i>T. lineata</i>),
+the Sapphirine Gurnard (<i>T. hirundo</i>), the Grey Gurnard (<i>T.
+gurnardus</i>), Bloch’s Gurnard (<i>T. cuculus</i>), the Piper (<i>T.
+lyra</i>), and the Long-finned Gurnard (<i>T. obscura</i> or <i>T.
+lucerna</i>). Singularly, the European species cross the Atlantic
+but rarely, the American species belonging chiefly to the division
+<i>Prionotus</i>.</p>
+
+<p>Several other genera belong to this family; for completeness’
+sake they are mentioned here, viz. <i>Bunocottus</i> from Cape
+Horn; <i>Rhamphocottus</i>, <i>Triglops</i> from Arctic North
+America; <i>Podabrus</i>, <i>Blepsias</i>, <i>Nautichthys</i>,
+<i>Scorpænichthys</i>, <i>Hemilepidotus</i>, <i>Artedius</i>, from the
+North Pacific; <i>Ptyonotus</i>, from Lake Ontario; <i>Polycaulus</i>
+from Indian Seas; Bembras from the Japanese Sea.</p>
+
+
+<h6 class="smcap">Fourteenth Family—Cataphracti.</h6>
+
+<p><i>Form of the body elongate, sub-cylindrical. Dentition feeble. Body
+completely cuirassed with osseous keeled scales or plates. A bony stay
+connects the angle of the præoperculum with the infraorbital ring.
+Ventrals thoracic.</i></p>
+
+<p>Marine fishes, and partly pelagic. <i>Petalopteryx</i>, from the
+chalk of Mount Lebanon, is supposed to have a resemblance to
+<i>Dactylopterus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Agonus.</span>—Head and body angular, covered with bony
+plates. Two dorsal fins; no pectoral appendages. Small teeth in
+the jaws.</p>
+</div>
+
+<p>Small fishes, from the northern parts of the temperate zone and
+extending into the Arctic Ocean; the genus reappears in the Southern
+Hemisphere on the coast of Chile. Of the eleven species known, one
+(<i>A. cataphractus</i>) is not uncommon on the coast of Great Britain.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aspidophoroides</span>, from Greenland, has a very similar
+form of the body, but possesses one short dorsal fin only.</p>
+</div>
+
+<p><span class="pagenum" id="Page_481">[481]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Siphagonus.</span>—With the snout produced into a long tube
+like a Syngnathus; chin prominent, with a barbel.</p>
+</div>
+
+<p>From Behring’s Strait and Japan.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Peristethus.</span>—Head parallelopiped, with the upper
+surface and the sides entirely bony; each præorbital prolonged
+into a long flat process, projecting beyond the snout. Body
+cuirassed with large bony plates. One continuous dorsal, or two
+dorsals, of which the second is the more developed. Two free
+pectoral appendages. Teeth none; lower jaw with barbels.</p>
+</div>
+
+<p>Singularly shaped fishes, of rather small size, from the Mediterranean,
+the warmer parts of the Atlantic, and the Indian Ocean; of the ten
+species known one species only has been found in the Pacific, near the
+Sandwich Islands. The European species is <i>P. cataphractum</i>. They
+are not common, and probably inhabit greater depths than the Gurnards,
+with which they have much in common as regards their habits.</p>
+
+  <div class="figcenter" id="fig216" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig216.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 216.—Dactylopterus volitans.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Dactylopterus.</span>—Head parallelopiped, with the upper
+surface and the sides entirely bony; scapula and angle of the
+præoperculum produced into long spines. Body with strongly
+keeled scales of moderate size; lateral line none. Two dorsal
+fins, the second not much longer than the first; pectoral very
+long, an organ of flying, with the upper portion detached
+and shorter. Granular teeth in the jaws; none on the palate.
+Air-bladder divided into two lateral halves, each with a larger
+muscle.</p>
+</div>
+
+<p><span class="pagenum" id="Page_482">[482]</span></p>
+
+<p>Of “Flying Gurnards” three species only are known, which are very
+abundant in the Mediterranean, the tropical Atlantic, and Indo-Pacific.
+They, and the Flying Herrings (Exocoetus), are the only fishes which
+are enabled by their long pectoral fins to take flying leaps out of the
+water, and deserve the name of “Flying-Fishes.” They are much heavier,
+and attain to a larger size, than the Exocoeti, specimens of eighteen
+inches in length not being scarce. When young, their pectorals are much
+shorter, and, consequently, they are unable to raise themselves out of
+the water (<i>Cephalacanthus</i>).</p>
+
+<p>The vertebral column shows a singular coalescence of the anterior
+vertebræ, which form a simple tube, as in <i>Fistularia</i>.</p>
+
+<hr class="tb">
+
+<p class="p-left"><span class="smcap">We</span> insert here as an appendix to this division the small
+family of <i>Pegasidæ</i>, the natural affinities of which are not yet
+clearly understood, but which resembles in some of its characters the
+<i>Cataphracti</i>.</p>
+
+
+<h6 class="smcap">Fifteenth Family—Pegasidæ.</h6>
+
+<p><i>Body entirely covered with bony plates, anchylosed on the trunk
+and movable on the tail. Barbels none. The margin of the upper jaw is
+formed by the intermaxillaries and their cutaneous prolongation, which
+extends downwards to the extremity of the maxillaries. Gill-cover
+formed by a large plate, homologous to the operculum, præoperculum,
+and sub-operculum; interoperculum a long fine bone, hidden below the
+gill-plate. One rudimentary branchiostegal. The gill-plate is united
+with the isthmus by a narrow membrane; gill-openings narrow, in front
+of the base of the pectoral fin. Gills four, lamellated. Pseudobranchiæ
+and air-bladder absent. One short dorsal and anal fin, opposite to each
+other. Ventral fin present. Ovarian sacs closed.</i></p>
+
+<p>One genus only is known, <i>Pegasus</i>. Its pectoral fins are broad,
+horizontal, long, composed of simple rays, some of which<span class="pagenum" id="Page_483">[483]</span> are sometimes
+spinous. Ventral fins one- or two-rayed. Upper part of the snout
+produced into a shorter or longer process. Mouth inferior, toothless.
+Suborbital ring well developed, forming a suture with the gill-cover.
+Vertebræ in small number, thin; no ribs. Four species are known,
+two of which are of a shorter, and the two others of a longer form.
+The former are <i>P. draconis</i>, common in the Indian Ocean, and
+<i>P. volans</i>, which is frequently stuck by the Chinese into the
+insect-boxes which they manufacture for sale. The two elongate species,
+<i>P. natans</i> and <i>P. lancifer</i>, are from the Chinese and
+Australian coasts. They are all very small fishes, probably living on
+sandy shoal places near the coast.</p>
+
+  <div class="figcenter" id="fig217" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig217.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 217.—Pegasus natans.</p>
+  </div>
+
+
+<h5 class="smcap">Ninth Division—Acanthopterygii Gobiiformes.</h5>
+
+<p><i>The spinous dorsal, or spinous portion of the dorsal is always
+present, short, either composed of flexible spines, or much less
+developed than the soft; the soft dorsal and anal of equal extent.
+No bony stay for the angle of the præoperculum. Ventrals thoracic or
+jugular, if present, composed of one spine and five, rarely four, soft
+rays. A prominent anal papilla.</i></p>
+
+<p>Shore-fishes, mostly exclusively marine, but some entering and living
+in fresh waters.</p>
+
+
+<h6 class="smcap">First Family—Discoboli.</h6>
+
+<p><i>Body thick or oblong, naked or tubercular. Teeth small.<span class="pagenum" id="Page_484">[484]</span> Ventral
+fins with one spine and five rays, all being rudimentary and forming
+the osseous support of a round disk, which is surrounded by a cutaneous
+fringe. Gill-openings narrow, the gill-membranes being attached to the
+isthmus.</i></p>
+
+<p>Carnivorous fishes, living at the bottom of the shores of northern
+seas. By their ventral disk they are enabled to attach themselves very
+firmly to rocks.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cyclopterus.</span>—Body thick, short, covered with a
+viscous, tubercular skin. Head large, snout short. Villiform
+teeth in the jaws, none on the palate. Skeleton soft, with but
+little earthy matter.</p>
+</div>
+
+  <div class="figcenter" id="fig218" style="max-width: 623px">
+     <img
+    class="p1"   
+    src="images/fig218.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 218.—Cyclopterus lumpus. <i>a</i>, Ventral disk.</p>
+  </div>
+
+<p>Three species of “Lump-suckers” are known from the northern temperate
+and the arctic zones. The common North European and North American
+species, <i>C. lumpus</i>, is known also by the names of “Cock-
+and Hen-Paddle.” It attains to a length of twenty-four inches, but
+generally is much smaller. It is difficult to remove it from any object
+to which it once has attached itself by means of its sucking-disk. Its
+skin is so thick as to more or less entirely conceal the first dorsal
+fin; it is covered with rough tubercles, the larger ones being arranged
+in four series along each side of the body. In young specimens these
+tubercles are absent. The arctic species, <i>C. spinosus</i>, has large
+conical plates on the head and<span class="pagenum" id="Page_485">[485]</span> body, each plate with a spine in the
+centre. Also of this species the young are naked, the plates making
+only gradually their appearance, in the form of groups of tubercles.
+Their development is irregular, as young specimens of the same size may
+be entirely naked or tubercular. This species ranges beyond the 81°
+lat. N.</p>
+
+  <div class="figcenter" id="fig219" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig219.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 219.—Young of Cyclopterus spinosus, from the
+Arctic Ocean, natural size.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Liparis.</span>—Body sub-cylindrical, enveloped in a more or
+less loose naked skin; head broad, obtuse. The infraorbital bone
+is styliform posteriorly, extending backwards to the margin of
+the præoperculum. One dorsal fin, with feeble flexible rays.
+Villiform teeth in the jaws, none on the palate.</p>
+</div>
+
+<p>Small fishes from the northern coasts of the temperate zone, ranging
+beyond the arctic circle. Eight species are known, of which two (<i>L.
+lineatus</i> and <i>L. montagui</i>) occur on the British coasts.</p>
+
+
+<h6 class="smcap">Second Family—Gobiidæ.</h6>
+
+<p><i>Body elongate, naked or scaly. Teeth generally small, sometimes
+with canines. The spinous dorsal fin, or portion of the dorsal fin, is
+the less developed, and composed of flexible spines; anal similarly
+developed as the soft dorsal. Sometimes the ventrals are united into
+a disk. Gill-opening more or less narrow, the gill-membranes being
+attached to the isthmus.</i></p>
+
+<p>Small carnivorous littoral fishes, many of which have become
+acclimatised in fresh water. They are very abundant with regard to
+species as well as individuals, and found on or<span class="pagenum" id="Page_486">[486]</span> near the coasts of all
+temperate and tropical regions. Geologically they appear first in the
+chalk.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gobius.</span>—Body scaly. Two dorsal fins, the anterior
+generally with six flexible spines. Ventral fins united, forming
+a disk which is not attached to the abdomen. Gill-opening
+vertical, moderately wide.</p>
+</div>
+
+  <div class="figcenter" id="fig220" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig220.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 220.—Gobius lentiginosus, from New Zealand.</p>
+  </div>
+
+<p>The “Gobies” are distributed over all temperate and tropical coasts,
+and abundant, especially on the latter. Nearly three hundred species
+have been described. They live especially on rocky coasts, attaching
+themselves firmly with their ventrals to a rock in almost any position,
+and thus withstanding the force of the waves. Many of the species seem
+to delight in darting from place to place in the rush of water which
+breaks upon the shore. Others live in quiet brackish water, and not
+a few have become entirely acclimatised in fresh water, especially
+lakes. The males of some species construct nests for the eggs,
+which they jealously watch, and defend even for some time after the
+young are hatched. Several species are found on the British coast:
+<i>G. niger</i>, <i>paganellus</i>, <i>auratus</i>, <i>minutus</i>,
+<i>ruthensparri</i>. Fossil species of this genus have been found at
+Monte Bolca.</p>
+
+<p>A very small Goby, <i>Latrunculus pellucidus</i>, common in some
+localities of the British Islands and other parts of Europe, is
+distinguished by its transparent body, wide mouth, and uniserial
+dentition. According to R. Collett it offers some very remarkable
+peculiarities. It lives one year only, being the first instance of an
+<i>annual vertebrate</i>. It spawns in June and July, the eggs are
+hatched in August, and the fishes attain their full growth in the
+months from October to December. In this stage the sexes are quite
+alike, both<span class="pagenum" id="Page_487">[487]</span> having very small teeth and feeble jaws. In April the
+males lose the small teeth, which are replaced by very long and strong
+teeth, the jaws themselves becoming stronger. The teeth of the females
+remain unchanged. In July and August all the adults die off, and in
+September only the fry are to be found.</p>
+
+<p>There are several other genera, closely allied to Gobius, as
+<i>Euctenogobius</i>, <i>Lophiogobius</i>, <i>Doliichthys</i>,
+<i>Apocryptes</i>, <i>Evorthodus</i>, <i>Gobiosoma</i> and
+<i>Gobiodon</i> (with scaleless body) <i>Triænophorichthys</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sicydium.</span>—Body covered with ctenoid scales of rather
+small size. Cleft of the mouth nearly horizontal, with the upper
+jaw prominent; lips very thick; the lower lip generally with a
+series of minute horny teeth. A series of numerous small teeth
+in upper jaw, implanted in the gum, and generally movable;
+the lower jaw with a series of conical widely-set teeth. Two
+dorsal fins, the anterior with six flexible spines. Ventral fins
+united, and forming a short disk, more or less adherent to the
+abdomen.</p>
+</div>
+
+<p>Small freshwater fishes inhabiting the rivers and rivulets of the
+islands of the tropical Indo-Pacific. About twelve species are known;
+one occurs in the West Indies. <i>Lentipes</i> from the Sandwich
+Islands is allied to <i>Sicydium</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Periophthalmus.</span>—Body covered with ctenoid scales of
+small or moderate size. Cleft of the mouth nearly horizontal,
+with the upper jaw somewhat longer. Eyes very close together,
+immediately below the upper profile, prominent, but retractile,
+with a well-developed outer eyelid. Teeth conical, vertical in
+both jaws. Two dorsal fins, the anterior with flexible spines;
+caudal fin with the lower margin oblique; base of the pectoral
+fin free, with strong muscles. Ventral fins more or less
+coalesced. Gill-openings narrow.</p>
+</div>
+
+<p>The fishes of this genus, and the closely-allied <i>Boleophthalmus</i>,
+are exceedingly common on the coasts of the tropical Indo-Pacific,
+especially on parts covered with mud or fucus. During ebb they leave
+the water and hunt for small crustaceans,<span class="pagenum" id="Page_488">[488]</span> and other small animals
+disporting themselves on the ground which is left uncovered by the
+receding water. With the aid of their strong pectoral and ventral fins
+and their tail, they hop freely over the ground, and escape danger
+by rapid leaps. The peculiar construction of their eyes, which are
+very movable, and can be thrust far out of their sockets, enables
+them to see in the air as well as in the water; when the eyes are
+retracted they are protected by a membranous eyelid. These fishes
+are absent in the eastern parts of the Pacific and on the American
+side of the Atlantic; but singularly enough one species reappears
+on the West African coast. About seven species are known (including
+<i>Boleophthalmus</i>), <i>P. koelreuteri</i> being one of the most
+common fishes of the Indian Ocean.</p>
+
+  <div class="figcenter" id="fig221" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig221.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 221.—Periophthalmus koelreuteri.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Eleotris.</span>—Body scaly; eyes of moderate size, lateral,
+not prominent. Teeth small. Two dorsal fins, the anterior
+generally with six spines. Ventrals not united, though close
+together, with one spine and five rays.</p>
+</div>
+
+<p>About sixty species are known from the tropics, only a few extending
+into the temperate zone. As regards form, they repeat almost all the
+modifications observed among the Gobies, from which they differ only
+in having the ventral fins non-coalescent. On the whole they are
+somewhat larger than the Gobies, and rather freshwater than marine
+species, some of them being abundant in the rivulets of the islands of<span class="pagenum" id="Page_489">[489]</span>
+the Indo-Pacific and Atlantic. Others have even penetrated into the
+inland-waters of the African continent.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Trypauchen.</span>—Body elongate, covered with minute scales;
+head compressed, with a deep cavity on each side, above the
+operculum. Teeth small, in a band. One dorsal, the spinous
+portion composed of six spines; dorsal and anal fins continuous
+with the caudal, ventral fins united.</p>
+</div>
+
+<p>Small fishes of singular aspect, from the East Indian coasts. Three
+species, of which <i>T. vagina</i> is common.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Callionymus.</span>—Head and anterior part of the body
+depressed, the rest cylindrical, naked. Snout pointed, with
+the cleft of the mouth narrow, horizontal, and with the upper
+jaw very protractile. Eyes rather large, more or less directed
+upwards. Teeth very small, palate smooth. A strong spine at the
+angle of the præoperculum. Two dorsal fins, the anterior with
+three or four flexible spines; ventrals five-rayed, widely apart
+from each other. Gill-openings very narrow, generally reduced to
+a foramen on the upper side of the operculum.</p>
+</div>
+
+<p>The “Dragonets” are small, and generally beautifully coloured marine
+fishes, inhabitants of the coasts of the temperate zone of the
+Old World; the minority of species live in tropical parts of the
+Indo-Pacific; and these seem to descend to somewhat greater depths
+than the littoral species of the northern hemisphere. Secondary sexual
+characters are developed in almost all the species, the mature males
+having the fin-rays prolonged into filaments, and the fin-membranes
+brightly ornamented. On the British coast one species (<i>C. draco</i>)
+is very common, and locally called “Skulpin.” About thirty species are
+known, many of which have the præopercular spine armed with processes
+or barbs. <i>Vulsus</i> is allied to <i>Callionymus</i>.</p>
+
+<p>Other genera belonging to this family are—<i>Benthophilus</i> from the
+Caspian Sea; <i>Amblyopus</i>, <i>Orthostomus</i>, <i>Platyptera</i>,
+<i>Luciogobius</i>, <i>Oxymetopon</i>, and, perhaps, <i>Oxuderces</i>.</p>
+
+<p><span class="pagenum" id="Page_490">[490]</span></p>
+
+
+<h5 class="smcap">Tenth Division—Acanthopterygii Blenniiformes.</h5>
+
+<p><i>Body low, sub-cylindrical or compressed, elongate. Dorsal fin very
+long; the spinous portion of the dorsal, if distinct, is very long,
+as well developed, as the soft, or much more; sometimes the entire
+fin is composed of spines only; anal more or less long; caudal fin
+subtruncated or rounded, if present. Ventral fins thoracic or jugular,
+if present.</i></p>
+
+
+<h6 class="smcap">First Family—Cepolidæ.</h6>
+
+<p><i>Body very elongate, compressed, covered with very small cycloid
+scales; eyes rather large, lateral. Teeth of moderate size. No bony
+stay for the angle of the præoperculum. One very long dorsal fin,
+which, like the anal, is composed of soft rays. Ventrals thoracic,
+composed of one spine and five rays. Gill-opening wide. Caudal vertebræ
+exceedingly numerous.</i></p>
+
+<p>The “Band-fishes” (<i>Cepola</i>) are small marine fishes, belonging
+principally to the fauna of the northern temperate zone; in the Indian
+Ocean the genus extends southwards to Pinang. The European species
+(<i>C. rubescens</i>) is found in isolated examples on the British
+coast, but is less scarce in some years than in others. These fishes
+are of a nearly uniform red colour.</p>
+
+
+<h6 class="smcap">Second Family—Trichonotidæ.</h6>
+
+<p><i>Body elongate, sub-cylindrical, covered with cycloid scales of
+moderate size. Eyes directed upwards. Teeth in villiform bands. No
+bony stay for the angle of the præoperculum. One long dorsal fin, with
+simple articulated rays, and without a spinous portion; anal long.
+Ventrals jugular, with one spine and five rays. Gill-opening very wide.
+The number of caudal vertebræ much exceeding that of the abdominal.</i></p>
+
+<p>Small marine fishes, belonging to two genera only,
+<i>Tricho</i><i>notus</i><span class="pagenum" id="Page_491">[491]</span> (<i>setigerus</i>) from Indian Seas,
+with some of the anterior dorsal rays prolonged into filaments; and
+<i>Hemerocoetes</i> (<i>acanthorhynchus</i>) from New Zealand, and
+sometimes found far out at sea on the surface.</p>
+
+<h6 class="smcap">Third Family—Heterolepidotidæ.</h6>
+
+<p><i>Body oblong, compressed, scaly; eyes lateral; cleft of the mouth
+lateral; dentition feeble. The angle of the præoperculum connected by a
+bony stay with the infraorbital ring. Dorsal long, with the spinous and
+soft portions equally developed; anal elongate. Ventrals thoracic, with
+one spine and five rays.</i></p>
+
+  <div class="figcenter" id="fig222" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig222.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 222.—Scale from the lateral line of Hemerocœtes
+acanthorhynchus, with lacerated margin.</p>
+  </div>
+
+  <div class="figcenter" id="fig223" style="max-width: 583px">
+     <img
+    class="p1"   
+    src="images/fig223.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 223.—<i>Chirus hexagrammus</i>, from Japan.</p>
+  </div>
+
+<p>Small shore-fishes, characteristic of the fauna of the Northern
+Pacific, some of the species occurring on the American as well as
+Asiatic side. They have been referred to several genera, as</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chirus</span>, which is distinguished by the presence of
+several lateral lines;</p>
+
+<p><span class="smcap">Ophiodon</span>, with one lateral line only, cycloid scales,
+and slightly armed præoperculum;</p>
+
+<p><span class="smcap">Agrammus</span>, with one lateral line only, ctenoid scales,
+and unarmed præoperculum; and</p>
+
+<p><span class="smcap">Zaniolepis</span>, with one lateral line and minute comb-like
+scales.</p>
+</div>
+
+<p><span class="pagenum" id="Page_492">[492]</span></p>
+
+
+<h6 class="smcap">Fourth Family—Blenniidæ.</h6>
+
+<p><i>Body elongate, low, more or less cylindrical, naked or covered with
+scales, which generally are small. One, two, or three dorsal fins
+occupying nearly the whole length of the back, the spinous portion,
+if distinct, being as much developed as the soft, or more; sometimes
+the entire fin is composed of spines; anal fin long. Ventrals jugular,
+composed of a few rays, and sometimes rudimentary or entirely absent.
+Pseudobranchiæ generally present.</i></p>
+
+<p>Littoral forms of great generic variety, occurring abundantly in
+all temperate and tropical seas. Some of the species have become
+acclimatised in fresh water, and many inhabit brackish water. With
+very few exceptions they are very small, some of the smallest
+fishes belonging to the family of “Blennies.” One of the principal
+characteristics of the Blennies is the ventral fin, which is formed by
+less than five rays, and has a jugular position. The Blennies have this
+in common with many Gadoids, and it is sometimes difficult to decide to
+which of these two families a fish should be referred. In such doubtful
+cases the presence of the pseudobranchiæ (which are absent in Gadoids)
+may be of assistance.</p>
+
+<p>In many Blennies the ventral fins have ceased to have any function, and
+become rudimentary, or are even entirely absent. In others the ventral
+fins, although reduced to cylindrical stylets, possess a distinct
+function, and are used as organs of locomotion, by the aid of which the
+fish moves rapidly over the bottom.</p>
+
+<p>The fossil forms are scarcely known; <i>Pterygocephalus</i> from Monte
+Bolca appears to have been a Blennioid.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Anarrhichas.</span>—Body elongate, with rudimentary scales;
+snout rather short; cleft of the mouth wide; strong conical
+teeth in the jaws, those on the sides with several pointed
+tubercles; a biserial band of large molar teeth on the palate.
+Dorsal fin long, with flexible spines; caudal separate. Ventrals
+none. Gill-openings wide.</p>
+</div>
+
+<p><span class="pagenum" id="Page_493">[493]</span></p>
+
+<p>The “Sea-wolf,” or “Sea-cat” (<i>A. lupus</i>), is a gigantic Blenny,
+attaining to a length of more than six feet. With its enormously strong
+tubercular teeth it is able to crush the hardest shells of Crustaceans
+or Mollusks, on which it feeds voraciously. It is an inhabitant of the
+northern seas, like two other allied species, all of which are esteemed
+as food by the inhabitants of Iceland and Greenland. Two other species
+of Sea-wolves occur in the corresponding latitudes of the North Pacific.</p>
+
+  <div class="figcenter" id="fig224" style="max-width: 508px">
+     <img
+    class="p1"   
+    src="images/fig224.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 224.—Teeth of the Wolf-fish, <i>Anarrhichas
+lupus</i>.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Blennius.</span>—Body moderately elongate, naked; snout
+short. A single dorsal, without detached portion; ventrals
+jugular, formed by a spine and two rays. Cleft of the mouth
+narrow; a single series of immovable teeth in the jaws;
+generally a curved tooth behind this series in both jaws, or
+in the lower only. A more or less developed tentacle above the
+orbit. Gill-opening wide.</p>
+</div>
+
+<p>About forty species of Blennius (in the restricted generic sense)
+are known from the northern temperate zone, the tropical Atlantic,
+Tasmania, and the Red Sea. But in the tropical Indian Ocean they are
+almost entirely absent, and replaced by other allied genera. Three
+species, found near the Sandwich Islands, are immigrants into the
+Pacific from the American Continent. They generally live on the coast,
+or attach themselves to floating objects, some species leading a
+pelagic life, hiding themselves in floating seaweed, in<span class="pagenum" id="Page_494">[494]</span> which they
+even propagate their species. All species readily accustom themselves
+to fresh water, and some (<i>B. vulgaris</i>) have become entirely
+acclimatised in inland lakes. British species are <i>B. gattorugine</i>
+(growing to a length of twelve inches), <i>B. ocellaris</i>, <i>B.
+galerita</i>, and <i>B. pholis</i>, the common “Shanny.”</p>
+
+<p><i>Chasmodes</i> is a genus allied to <i>Blennius</i>, from the
+Atlantic coasts of temperate North America.</p>
+
+  <div class="figcenter" id="fig225" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig225.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 225.—Petroscirtes bankieri, from Hong-Kong.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Petroscirtes.</span>—Body moderately elongate, naked. Snout
+generally short. A single dorsal fin; ventrals composed of two
+or three rays. Cleft of the mouth narrow; a single series of
+immovable teeth in the jaws; a strong curved canine tooth behind
+this series, that of the lower jaw much stronger than that of
+the upper. Head sometimes with tentacles. Gill-opening reduced
+to a small fissure above the root of the pectoral.</p>
+</div>
+
+<p>Thirty species, from the tropical Indo-Pacific, of small size.</p>
+
+  <div class="figcenter" id="fig226" style="max-width: 281px">
+     <img
+    class="p1"   
+    src="images/fig226.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 226.—Dentition of the same, enlarged.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Salarias.</span>—Body moderately elongate, naked; snout
+short, with transverse cleft of the mouth; a series of numerous
+small teeth in the jaws, implanted in the gum and movable;
+generally a curved canine tooth on each side of the lower
+jaw, behind the series of small teeth. Dorsal fin continuous,
+sometimes divided into two portions by a more or less deep notch
+without a detached<span class="pagenum" id="Page_495">[495]</span> anterior part. Ventral fins with two or
+three rays. A tentacle above the orbit. Gill-openings wide.</p>
+</div>
+
+<p>Sixty species are known from the tropical zone, extending northwards to
+Madeira, southwards to Chile and Tasmania. In certain individuals of
+some of the species a longitudinal cutaneous crest is developed; all
+young individuals lack it, and in some other species it is invariably
+absent. Singularly enough this crest is not always a sexual character,
+as one might have supposed from analogy, but in some species at least
+it is developed in both sexes. Mature males, however, have generally
+higher dorsal fins and a more intense and variegated coloration than
+females and immature males, as is also the case in <i>Blennius</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Clinus.</span>—Body moderately elongate, covered with small
+scales; snout rather short; a narrow band or series of small
+teeth in the jaws and on the palate. Dorsal fin formed by
+numerous spines and a few soft rays, without a detached anterior
+portion; anal spines two. Ventrals with two or three rays. A
+tentacle above the orbit. Gill-opening wide.</p>
+</div>
+
+<p>Thirty species, from the coasts of tropical America and the southern
+temperate zone. Three other genera are closely allied to Clinus,
+viz. <i>Cristiceps</i> and <i>Cremnobates</i>, in which the three
+anterior dorsal spines are detached from the rest of the fin; and
+<i>Tripterygium</i>, with three distinct dorsal fins, of which the
+two anterior are spinous. The species of these genera are as numerous
+as those of <i>Clinus</i>, occurring in many parts of tropical seas,
+in the Mediterranean, and being especially well represented in South
+Australia and New Zealand.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Stichæus.</span>—Body elongate, covered with very small
+scales; lateral line more or less distinct, sometimes several
+lateral lines. Snout short; very small teeth in the jaws, and
+generally on the palate. Dorsal fin long, formed by spines
+only. Ventrals with two or three rays. Caudal fin distinct.
+Gill-openings rather wide.</p>
+</div>
+
+<p><span class="pagenum" id="Page_496">[496]</span></p>
+
+<p>Small fishes, peculiar to the coasts near the arctic circle, ranging
+southwards to the coasts of Japan and Scandinavia. Ten species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Blenniops.</span>—Body moderately elongate, covered with very
+small scales; lateral line none. Snout short; small teeth in
+the jaws, none on the palate. Dorsal fin long, formed by spines
+only. Ventrals with one spine and three rays. Caudal distinct.
+Gill-openings of moderate width, the gill-membranes coalescent
+across the isthmus.</p>
+</div>
+
+<p>A fine but not common kind of Blenny (<i>B. ascanii</i>), from the
+British and Scandinavian coasts.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centronotus.</span>—Body elongate, covered with very small
+scales; lateral line none. Snout short; very small teeth in the
+jaws. Dorsal fin long, formed by spines only. Ventrals none or
+rudimentary; caudal separate. Gill-openings of moderate width,
+gill-membranes coalescent.</p>
+</div>
+
+<p>Ten species are known from the northern coasts; southwards the genus
+extends to the coasts of France, New York, California, and Japan. <i>C.
+gunellus</i>, or the “Gunnel-fish” or “Butter-fish,” is common on the
+British coasts. <i>Apodichthys</i> is allied to <i>Centronotus</i>, but
+the vertical fins are confluent; and a very large, excavated, pen-like
+spine lies hidden in a pouch in front of the anal fin. This spine is
+evidently connected in some way with the generative organs, as a furrow
+leads from the orifice of the oviduct to the groove of the spine. One
+species from the Pacific coast of North America. <i>Xiphidion</i> is
+another closely allied genus from the same locality.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cryptacanthodes.</span>—Body very elongate, naked, with
+a single lateral line. Head with the muciferous system well
+developed. Eye rather small. Conical teeth in the jaws, on
+the vomer and palatine bones. One dorsal formed by spines
+only; caudal connected with dorsal and anal. Ventrals none.
+Gill-opening of moderate width, with the gill-membranes joined
+to the isthmus.</p>
+</div>
+
+<p><span class="pagenum" id="Page_497">[497]</span></p>
+
+<p>One species (<i>C. maculatus</i>) from the Atlantic coasts of North
+America.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Patæcus.</span>—Body oblong, elevated anteriorly; snout
+short, with subvertical anterior profile; minute teeth in the
+jaws and on the vomer. Dorsal fin with the anterior spines
+strong and long, continuous with the caudal; ventrals none.
+Gill-openings wide.</p>
+</div>
+
+  <div class="figcenter" id="fig227" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig227.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 227.—Patæcus fronto.</p>
+  </div>
+
+<p>Three species of this singular form are known from South and West
+Australia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Zoarces.</span>—Body elongate, with the scales rudimentary;
+conical teeth in the jaws. Dorsal fin long, with a depression
+on the tail, which is formed by a series of spines much shorter
+than the rays. No other fin-spines. No separate caudal fin.
+Ventrals short, formed by three or four rays. Gill-openings wide.</p>
+</div>
+
+<p>Two species are known, one from the European, and the other from the
+North American side of the Atlantic. The former, <i>Z. viviparus</i>,
+is well known by the name of “Viviparous Blenny;” as is signified by
+this name it produces its young alive. These are so matured at the
+time of their birth that on their first exclusion they swim about with
+the utmost agility. No fewer than from two to three hundred young are
+sometimes produced by one female, and the abdomen of the mother is so
+distended before parturition that it is impossible to touch it without
+causing them to be extruded. Full grown individuals are about twelve
+inches long, but the<span class="pagenum" id="Page_498">[498]</span> American species (<i>Z. anguillaris</i>) attains
+to a length of two or three feet.</p>
+
+<p>Other genera of the family of Blennoids are:—<i>Blennophis</i>,
+<i>Nemophis</i>, <i>Plagiotremus</i>, <i>Neoclinus</i>,
+<i>Cebidichthys</i>, <i>Myxodes</i>, <i>Heterostichus</i>,
+<i>Dictyosoma</i>, <i>Lepidoblennius</i>, <i>Dactyloscopus</i>,
+<i>Gunellichthys</i>, <i>Urocentrus</i>, <i>Stichæopsis</i>,
+<i>Sticharium</i>, <i>Notograptus</i>, <i>Pholidichthys</i>, and
+<i>Pseudoblennius</i>.</p>
+
+
+<h6 class="smcap">Fifth Family—Acanthoclinidæ.</h6>
+
+<p><i>Body elongate, low, compressed, covered with small scales. One
+dorsal fin, occupying nearly the whole of the back, and chiefly
+composed of spines. Anal fin long, with numerous spines. Ventrals
+jugular, composed of a few rays only.</i></p>
+
+<p>Of this family one fish only is known (<i>Acanthoclinus littoreus</i>),
+a small Blenny abundant on the coast of New Zealand.</p>
+
+
+<h6 class="smcap">Sixth Family—Mastacembelidæ.</h6>
+
+<p><i>Body elongate, eel-like, covered with very small scales. Mandible
+long, but little moveable. Dorsal fin very long, the anterior portion
+composed of numerous short isolated spines; anal fin with spines
+anteriorly. Ventrals none. The humeral arch is not suspended from the
+skull. Gill-openings reduced to a slit at the lower part of the side of
+the head.</i></p>
+
+<p>Freshwater-fishes characteristic of and almost confined to the Indian
+region. The structure of the mouth and of the branchial apparatus, the
+separation of the humeral arch from the skull, the absence of ventral
+fins, the anatomy of the abdominal organs, affords ample proof that
+these fishes are Acanthopterygian eels. Their upper jaw terminates in a
+pointed moveable appendage, which is concave and transversely striated
+inferiorly in <i>Rhynchobdella</i>, and without transverse striæ in
+<i>Mastacembelus</i>: the only two genera of this family.<span class="pagenum" id="Page_499">[499]</span> Thirteen
+species are known, of which <i>Rh. aculeata</i>, <i>M. pancalus</i>
+and <i>M. armatus</i> are extremely common, the latter attaining to
+a length of two feet. Outlying species are <i>M. aleppensis</i> from
+Mesopotamia and Syria, and <i>M. cryptacanthus</i>, <i>M. marchei</i>,
+and <i>M. niger</i>, from West Africa.</p>
+
+  <div class="figcenter" id="fig228" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig228.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 228.—Mastacembelus argus, from Siam.</p>
+  </div>
+
+
+<h5 class="smcap">Eleventh Division—Acanthopterygii Mugiliformes.</h5>
+
+<p><i>Two dorsal fins more or less remote from each other; the anterior
+either short, like the posterior, or composed of feeble spines. Ventral
+fins with one spine and five rays, abdominal.</i></p>
+
+
+<h6 class="smcap">First Family—Sphyrænidæ.</h6>
+
+<p><i>Body elongate, sub-cylindrical, covered with small cycloid scales;
+lateral line continuous. Cleft of the mouth wide, armed with strong
+teeth. Eye lateral, of moderate size. Vertebræ twenty-four.</i></p>
+
+<p>This family consists of one genus only, <i>Sphyræna</i>, generally
+called “Barracudas,” large voracious fishes from the tropical and
+sub-tropical seas, which prefer the vicinity of the coast to the open
+sea. They attain to a length of eight feet, and a weight of forty
+pounds; individuals of this large size are dangerous to bathers. They
+are generally used as food, but sometimes (especially in the West
+Indies) their flesh assumes poisonous qualities, from having fed on
+smaller poisonous fishes. Seventeen species.</p>
+
+<p>The Barracudas existed in the tertiary epoch, their remains being
+frequently found at Monte Bolca. Some other fossil genera have been
+associated with them, but as they are known from jaws and teeth
+or vertebræ only, their position in the<span class="pagenum" id="Page_500">[500]</span> system cannot be exactly
+determined; thus <i>Sphyrænodus</i> and <i>Hypsodon</i> from the chalk
+of Lewes, and the London clay of Sheppey. The American <i>Portheus</i>
+is allied to <i>Hypsodon</i>. Another remarkable genus from the chalk,
+<i>Saurocephalus</i>, has been also referred to this family.<a id="FNanchor_44" href="#Footnote_44" class="fnanchor">[44]</a></p>
+
+
+<h6 class="smcap">Second Family—Atherinidæ.</h6>
+
+<p><i>Body more or less elongate, sub-cylindrical, covered with scales of
+moderate size; lateral line indistinct. Cleft of the mouth of moderate
+width, with the dentition feeble. Eye lateral, large or of moderate
+size. Gill-openings wide. Vertebræ very numerous.</i></p>
+
+<p>Small carnivorous fishes inhabiting the seas of the temperate and
+tropical zones; many enter fresh water, and some have been entirely
+acclimatised in it. This family seems to have been represented in the
+Monte Bolca formation by <i>Mesogaster</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Atherina.</span>—Teeth very small; scales cycloid. The first
+dorsal is short and entirely separated from the second. Snout
+obtuse, with the cleft of the mouth straight, oblique, extending
+to or beyond the anterior margin of the eye.</p>
+</div>
+
+<p>The Atherines are littoral fishes, living in large shoals, which habit
+has been retained by the species acclimatised in fresh water. They
+rarely exceed a length of six inches, but are nevertheless esteemed
+as food. From their general resemblance to the real Smelt they are
+often thus misnamed, but may always be readily recognised by their
+small first spinous dorsal fin. The young, for some time after they
+are hatched, cling together in dense masses, and in numbers almost
+incredible. The inhabitants of the Mediterranean<span class="pagenum" id="Page_501">[501]</span> coast of France call
+these newly hatched Atherines “Nonnat” (unborn). Some thirty species
+are known, of which <i>A. presbyter</i> and <i>A. boyeri</i> occur on
+the British coast.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Atherinichthys</span>, distinguished from <i>Atherina</i> in
+having the snout more or less produced; and the cleft of the
+mouth generally does not extend to the orbit.</p>
+</div>
+
+<p>These Atherines are especially abundant on the coasts and in the fresh
+waters of Australia and South America. Of the twenty species known,
+several attain a length of eighteen inches and a weight of more than a
+pound. All are highly esteemed as food; but the most celebrated is the
+“Pesce Rey” of Chile (<i>A. laticlavia</i>).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Tetragonurus.</span>—Body rather elongate, covered with
+strongly keeled and striated scales. The first dorsal fin is
+composed of numerous feeble spines, and continued on to the
+second. Lower jaw elevated, with convex dental margin, and armed
+with compressed, triangular, rather small teeth, in a single
+series.</p>
+</div>
+
+<p>This very remarkable fish is more frequently met with in the
+Mediterranean than in the Atlantic, but generally scarce. Nothing is
+known of its habits; when young it is one of the fishes which accompany
+Medusæ, and, therefore, it must be regarded as a pelagic form.
+Probably, at a later period of its life, it descends to greater depths,
+coming to the surface at night only. It grows to a length of eighteen
+inches.</p>
+
+
+<h6 class="smcap">Third Family—Mugilidæ.</h6>
+
+<p><i>Body more or less oblong and compressed, covered with cycloid scales
+of moderate size; lateral line none. Cleft of the mouth narrow or of
+moderate width, without or with feeble teeth. Eye lateral, of moderate
+size. Gill-opening wide. The anterior dorsal fin composed of four stiff
+spines. Vertebræ twenty-four.</i></p>
+
+<p>The “Grey Mullets” inhabit in numerous species and in great numbers the
+coasts of the temperate and tropical<span class="pagenum" id="Page_502">[502]</span> zones. They frequent brackish
+waters, in which they find an abundance of food which consists chiefly
+of the organic substances mixed with mud or sand; in order to prevent
+larger bodies from passing into the stomach, or substances from passing
+through the gill-openings, these fishes have the organs of the pharynx
+modified into a filtering apparatus. They take in a quantity of sand or
+mud, and, after having worked it for some time between the pharyngeal
+bones, they eject the roughest and indigestible portion of it. The
+upper pharyngeals have a rather irregular form; they are slightly
+arched, the convexity being directed towards the pharyngeal cavity,
+tapering anteriorly and broad posteriorly. They are coated with a thick
+soft membrane, which reaches far beyond the margin of the bone, at
+least on its interior posterior portion; this membrane is studded all
+over with minute horny cilia. The pharyngeal bone rests upon a large
+fatty mass, giving it a considerable degree of elasticity. There is a
+very large venous sinus between the anterior portion of the pharyngeal
+and the basal portion of the branchial arches. Another mass of fat,
+of elliptical form, occupies the middle of the roof of the pharynx,
+between the two pharyngeal bones. Each branchial arch is provided
+on each side, in its whole length, with a series of closely-set
+gill-rakers, which are laterally bent downwards, each series closely
+fitting into the series of the adjoining arch; they constitute together
+a sieve, admirably adapted to permit a transit for the water, retaining
+at the same time every other substance in the cavity of the pharynx.</p>
+
+<p>The lower pharyngeal bones are elongate, crescent-shaped, and
+broader posteriorly than anteriorly. Their inner surface is concave,
+corresponding to the convexity of the upper pharyngeals, and provided
+with a single series of lamellæ, similar to those of the branchial
+arches, but reaching across the bone from one margin to the other.</p>
+
+<p><span class="pagenum" id="Page_503">[503]</span></p>
+
+<p>The intestinal tract shows no less peculiarities. The lower portion
+of the œsophagus is provided with numerous long thread-like papillæ,
+and continued into the oblong-ovoid membranaceous cœcal portion of the
+stomach, the mucosa of which forms several longitudinal folds. The
+second portion of the stomach reminds one of the stomach of birds;
+it communicates laterally with the other portion, is globular, and
+surrounded by an exceedingly strong muscle. This muscle is not divided
+into two as in birds, but of great thickness in the whole circumference
+of the stomach, all the muscular fasciculi being circularly arranged.
+The internal cavity of this stomach is rather small, and coated with a
+tough epithelium, longitudinal folds running from the entrance opening
+to the pyloric, which is situated opposite to the other. A low circular
+valve forms a pylorus. There are five rather short pyloric appendages.
+The intestines make a great number of circumvolutions, and are seven
+feet long in a specimen thirteen inches in length.</p>
+
+  <div class="figcenter" id="fig229" style="max-width: 601px">
+     <img
+    class="p1"   
+    src="images/fig229.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 229.—Mugil proboscideus.</p>
+  </div>
+
+<p>Some seventy species of Grey Mullets are known, the majority of which
+attain to a weight of about four pounds, but there are many which
+grow to ten and twelve pounds. All are eaten, and some even esteemed,
+especially when taken out of fresh water. If attention were paid to
+their cultivation, great profits could be made by fry being transferred
+into suitable<span class="pagenum" id="Page_504">[504]</span> backwaters on the shore, in which they rapidly grow
+to a marketable size. Several species are more or less abundant on
+the British coasts, as <i>Mugil octo-radiatus</i> (Fig. <a href="#fig105">105</a>, p. 254),
+<i>M. capito</i>, <i>M. auratus</i> (Fig. <a href="#fig106">106</a>, p. 254), and <i>M.
+septentrionalis</i> (Fig. <a href="#fig107">107</a>, p. 254), which, with the aid of the
+accompanying figures, and by counting the rays of the anal fin, may
+be readily distinguished—<i>M. octo-radiatus</i> having eight, and
+<i>M. capito</i> and <i>M. auratus</i> nine soft rays. A species
+inhabiting fresh waters of Central America (<i>M. proboscideus</i>)
+has the snout pointed and fleshy, thus approaching certain other
+freshwater and littoral Mullets, which, on account of a modification
+of the structure of the mouth, have been formed into a distinct genus,
+<i>Agonostoma</i>. <i>Myxus</i> comprises Mullets with teeth more
+distinct than in the typical species.</p>
+
+<p>This genus existed in the tertiary epoch, remains of a species having
+been found in the gypsum of Aix, in Provence.</p>
+
+
+<h5 class="smcap">Twelfth Division—Acanthopterygii Gastrosteiformes.</h5>
+
+<p><i>The spinous dorsal is composed of isolated spines if present;
+the ventrals are either thoracic or have an abdominal position in
+consequence of the prolongation of the pubic bones which are attached
+to the humeral arch. Mouth small, at the end of the snout which is
+generally more or less produced.</i></p>
+
+
+<h6 class="smcap">First Family—Gastrosteidæ.</h6>
+
+<p><i>Body elongate, compressed. Cleft of the mouth oblique; villiform
+teeth in the jaws. Opercular bones not armed; infraorbitals covering
+the cheek; parts of the skeleton forming incomplete external mails.
+Scales none, but generally large scutes along the side. Isolated spines
+in front of the soft dorsal fin. Ventral fins abdominal, joined to
+the pubic bone, composed of a spine and a small ray. Branchiostegals
+three.</i></p>
+
+<p><span class="pagenum" id="Page_505">[505]</span></p>
+
+  <div class="figcenter" id="fig230" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig230.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 230.—Gastrosteus noveboracensis.</p>
+  </div>
+
+<p>Of “Sticklebacks” (<i>Gastrosteus</i>) about ten species are
+satisfactorily known, one of which (<i>G. spinachia</i>) lives in
+salt and brackish water, whilst the others inhabit principally fresh
+waters, although they all are able to exist in the sea. They are
+confined to the Temperate and Arctic zones of the northern hemisphere.
+The British freshwater species are the Three-spined Stickleback (<i>G.
+aculeatus</i>), which sometimes, especially in Central Europe, lacks
+scutes, sometimes has a series of scutes along the side of the body;
+the Four-spined Stickleback (<i>G. spinulosus</i>) and the Nine-spined
+Stickleback (<i>G. pungitius</i>). The commonest North American species
+is <i>G. noveboracensis</i>. The habits of all the freshwater species
+are very similar. The common European species (<i>G. aculeatus</i>)
+is an active and greedy little fish, extremely destructive to the fry
+of other species, and consequently injurious in ponds where these are
+sought to be preserved. It is scarcely to be conceived what damage
+these little fishes do, and how greatly detrimental they are to the
+increase of all the fishes in general among which they live; for it is
+with the utmost industry, sagacity, and greediness that they seek out
+and destroy all the young fry that come their way. A small Stickleback,
+kept in an aquarium, devoured, in five hours’ time, seventy-four young
+dace, which were about a quarter of an inch long, and of the thickness
+of a horse hair. Two days after it swallowed sixty-two; and would,
+probably, have eaten as many every day could they have been procured.
+The Stickleback<span class="pagenum" id="Page_506">[506]</span> sometimes swarms in prodigious numbers. Pennant states
+that at Spalding, in Lincolnshire, there was once in seven years
+amazing shoals, which appear in the Welland, coming up the river in the
+form of a vast column. The quantity may, perhaps, be conceived from the
+fact that a man employed in collecting them, gained, for a considerable
+time, four shillings a-day by selling them at the rate of a halfpenny a
+bushel. Costa, who studied the manners of these small fishes, relates
+that, on the approach of spawning time, the male builds a nest of
+stalks of grass and other matters in a hollow of the bottom, a little
+above three inches wide and about six inches and a half deep, creeping
+over the materials on his belly, and cementing them with the mucus that
+exudes from his skin. The bottom of the nest is first laid, then the
+sides are raised, and lastly the top is covered over. A small hole is
+left on one side for an entrance. When the erection is complete, he
+seeks out a female, and conducting her, Costa says, with many caresses,
+to the nest, introduces her by the door into the chamber. In a few
+minutes she has laid two or three eggs, after which she bores a hole on
+the opposite side of the nest to that by which she entered, and makes
+her escape. The nest has now two doors, and the eggs are exposed to
+the cool stream of water, which, entering by one door flows out at the
+other. Next day the male goes again in quest of a female, and sometimes
+brings back the same, sometimes finds a new mate. This is repeated
+until the nest contains a considerable number of eggs, and each time
+the male rubs his side against the female and passes over the eggs.
+Next the male watches a whole month over his treasure, defending it
+stoutly against all invaders, and especially against his wives, who
+have a great desire to get at the eggs. When the young are hatched and
+able to do for themselves his cares cease.</p>
+
+<p>The Sea-Stickleback (<i>G. spinachia</i>) is likewise a nest<span class="pagenum" id="Page_507">[507]</span> builder,
+choosing for its operations especially the shallows of brackish water,
+which are covered with <i>Zostera</i>.</p>
+
+
+<h6 class="smcap">Second Family—Fistulariidæ.</h6>
+
+<p><i>Fishes of greatly elongated form; the anterior bones of the skull
+are much produced, and form a long tube, terminating in a narrow mouth.
+Teeth small; scales none, or small. The spinous dorsal fin is either
+formed by feeble isolated spines or entirely absent; the soft dorsal
+and anal of moderate length, ventral fins thoracic or abdominal,
+composed of five or six rays, without spine; if abdominal, they are
+separate from the pubic bones, which remain attached to the humeral
+arch. Branchiostegals five.</i></p>
+
+<p>The “Flute-mouths” are also frequently called “Pipe-fishes,” a name
+which they have in common with the Syngnathidæ. They are gigantic
+marine Sticklebacks, living near the shore, from which they are
+frequently driven into the open sea; some of the species, therefore,
+have a wide geographical range. Probably all enter brackish water. They
+are distributed over the whole of the tropical and sub-tropical parts
+of the Atlantic and Indo-Pacific. The species are few in number, but
+some of them are very common.</p>
+
+<p>This family is well represented in Eocene formations; some of
+the remains belonging to the existing genera, <i>Fistularia</i>,
+<i>Aulostoma</i>, and <i>Auliscops</i>, the two former of which occur
+not rarely at Monte Bolca and in the schists of Glaris. Well-preserved
+remains of <i>Auliscops</i> have been found in the Marl-slates of the
+highlands of Padang in Sumatra. Extinct genera from Monte Bolca are
+<i>Urosphen</i>, the cylindrical body of which is terminated by a large
+cuneiform fin; and <i>Rhamphosus</i>, which has an immense spinous ray,
+denticulated behind, inserted on the nape.</p>
+
+<p><span class="pagenum" id="Page_508">[508]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Fistularia.</span>—Body scaleless; caudal fin forked, with
+the two middle rays produced into a filament; no free dorsal
+spines.</p>
+</div>
+
+<p>Three species are known, common on the shores of the Tropical Atlantic
+(<i>F. tabaccaria</i>) and Indian Oceans (<i>F. serrata</i> and <i>F.
+depressa</i>); they attain to a length of from four to six feet.</p>
+
+<p>The anterior portion of the vertebral column shows the same peculiarity
+as in <i>Dactylopterus</i>; it is a long compressed tube, composed of
+four elongate vertebræ, which are perfectly anchylosed; each of them
+has a pair of small foramina for blood-vessels. The neural spines and
+parapophyses of this tubiform portion are confluent into thin laminæ,
+the lateral of which are wing-like, and expanded in their anterior half.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aulostoma.</span>—Body covered with small scales. Caudal fin
+rhombic, without prolonged rays; a series of isolated feeble
+dorsal spines. Teeth rudimentary.</p>
+</div>
+
+<p>Two species from the Tropical Atlantic and Indian Oceans.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Auliscops.</span>—Body naked. Ventrals thoracic. Numerous
+spines in front of the dorsal fin.</p>
+</div>
+
+<p>One species (<i>A. spinescens</i>) from the Pacific coast of North
+America. <i>Aulorhynchus</i> from the same sea, and <i>Aulichthys</i>
+from Japan, are allied genera.</p>
+
+
+<h5 class="smcap">Thirteenth Division—Acanthopterygii Centrisciformes.</h5>
+
+<p><i>Two dorsal fins; the spinous short, the soft and the anal
+of moderate extent. Ventral fins truly abdominal, imperfectly
+developed.</i></p>
+
+<p>This division consists of one family, <i>Centriscidæ</i>, with two
+genera. The fishes belonging to it are very small, marine, and, in
+consequence of their limited power of swimming, often driven out into
+the open sea. They have the same<span class="pagenum" id="Page_509">[509]</span> structure of the mouth and snout
+as the Fistulariidæ, but combine with it peculiarities of the shape
+of body, of the structure of the vertical fins, and of the relations
+between endo- and exo-skeleton, which render them altogether a singular
+and interesting type. <i>Amphisile</i> has been found in a fossil state
+at Monte Bolca.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centriscus.</span>—Body oblong or elevated, compressed,
+covered with small rough scales; lateral line none; some bony
+strips on the side of the back, and on the margin of the thorax
+and abdomen; the former, in one species, are confluent and form
+a shield. Teeth none. Two dorsal fins, the first with one of the
+spines very strong. Ventral fins small, abdominal, composed of
+five soft rays. Four branchiostegals.</p>
+</div>
+
+  <div class="figcenter" id="fig231" style="max-width: 580px">
+     <img
+    class="p1"   
+    src="images/fig231.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 231.—Centriscus humerosus.</p>
+  </div>
+
+<p>Of the four species the most generally known is <i>C. scolopax</i>,
+the “Trumpet-fish” or “Bellows-fish,” which rarely occurs on the south
+coast of England, is more common farther south, and reappears in
+Tasmania. The allied <i>C. gracilis</i> is one of the fishes common
+to the Mediterranean and Japanese Seas. The species figured, <i>C.
+humerosus</i>, occurs on the coast of South Australia, and is very
+scarce.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Amphisile.</span>—Body elongate, strongly compressed,
+provided with a dorsal cuirass, which is formed by portions of
+the skeleton; the longitudinal axis of the tail is not in the
+same line with that of the trunk. Scales none. Teeth none. Two
+dorsal fins situated on the hindmost part of the back; ventral
+fins rudimentary, abdominal. Three or four branchiostegals.</p>
+</div>
+
+<p><span class="pagenum" id="Page_510">[510]</span></p>
+
+<p>The three species known of this genus are found in the tropical
+Indo-Pacific. Their body is so thin that it has the appearance of
+being artificially compressed between two sheets of paper; it is
+semi-transparent, especially in the region of the air-bladder. The
+structure of the vertebral column is extremely singular and unique
+among Acanthopterygians. The abdominal portion is more than four
+times as long as the caudal; nevertheless it is composed of only
+six vertebræ, whilst the latter consists of fourteen. The abdominal
+vertebræ are extremely slender, the third alone being nearly as long
+as the whole caudal portion; they have a slight ridge superiorly
+and inferiorly, and on each side; the whole portion lying in the
+uppermost concavity of the dorsal cuirass. The caudal vertebræ are
+extremely short, and the strength of their neural and hæmal spines
+is in proportion to their size. The dorsal cuirass is not a dermal
+production, but formed by modified parts of the endoskeleton; its
+composition, the number and condition of its single parts, and,
+finally, the first dorsal spine, which in <i>A. punctulata</i> is so
+singularly attached to it, favour this opinion. The plates, which
+occupy the vertebral line, would correspond to the neural spines, and
+the lateral plates on which the ribs are suspended to the parapophyses.
+<i>Amphisile</i> may be considered as a Chelonian form among fishes.</p>
+
+
+<h5 class="smcap">Fourteenth Division—Acanthopterygii Gobiesociformes.</h5>
+
+<p><i>No spinous dorsal; the soft and the anal short or of moderate
+length, situated on the tail; ventral fins subjugular, with an adhesive
+apparatus between them. Body naked.</i></p>
+
+<p>These fishes are well characterised by their single dorsal fin, and by
+their adhesive ventral apparatus, which has only an external similarity
+to the organ observed in <i>Cyclopterus</i> and <i>Liparis</i>; its
+structure is typically different from it.<span class="pagenum" id="Page_511">[511]</span> Whilst in those genera the
+ventral fins occupy the centre of the disk forming its base, these
+fins are here widely apart from each other, as in <i>Callionymus</i>,
+forming only a portion of the periphery of the disk, which is completed
+by a cartilaginous expansion of the coracoid bones. The following
+description of its structure is taken from <i>Sicyases sanguineus</i>,
+but it is essentially the same in all the genera.</p>
+
+<p>The whole disk is exceedingly large, subcircular, longer than broad,
+its length being one-third of the whole length of the fish. The central
+portion is formed merely by skin, which is separated from the pelvic
+or pubic bones by several layers of muscles. The peripheric portion is
+divided into an anterior and posterior part by a deep notch behind the
+ventrals. The anterior peripheric portion is formed by the four ventral
+rays, the membrane between them, and a broad fringe which extends
+anteriorly from one ventral to the other; this fringe is a fold of
+the skin, containing on each side the rudimentary ventral spine, but
+no cartilage. The posterior peripheric portion is suspended on each
+side from the coracoid, the upper bone of which is exceedingly broad,
+becoming a free movable plate behind the pectoral. A broad cartilage
+is firmly attached to it. The lower bone of the coracoid is of a
+triangular form, and supports a very broad fold of the skin, extending
+from one side to the other, and containing a cartilage which runs
+through the whole of that fold. Five processes of the cartilage are
+continued into the soft striated margin in which the disk terminates
+posteriorly. The surface of the disk is coated with thick epidermis,
+like the sole of the foot of higher animals. The epidermis is divided
+into many polygonal plates; there are no such plates between the roots
+of the ventral fins.</p>
+
+<p>Not less unique is the structure of the bones which have some
+relation to this external adhesive apparatus. As exemplified by
+<i>Chorismochismus dentex</i> the coracoid is well developed,<span class="pagenum" id="Page_512">[512]</span> and, as
+usual, composed of two pieces, the upper of which is not suspended from
+the humerus, but fixed by a ligament to the hinder margin of the carpal
+bones. It is a broad lamella, dilated posteriorly into the cartilage,
+which is externally visible; the lower piece is narrower, and fixed to
+the extremity of the pubic bone of its side. The pubic bones are united
+by suture, and form together a heart-shaped disk, the point of which
+is produced backwards. The anterior portion of the disk is concave,
+with a bony longitudinal bridge and a feeble transverse ridge. The disk
+is fixed to the humeral bones by the convex portions of its anterior
+margin, whilst the convex portions of the lateral margins serve as
+base for the ventral fins. The latter are composed of one spine, which
+is transformed into a broad, thin, and curved plate, hidden below the
+skin, and apparently of four rays; but on closer examination we find
+that the hidden ray has a longitudinal groove anteriorly, in which
+another thinner ray lies concealed. This ray is quite free, and not
+joined to the pubic bone.</p>
+
+<p>The fishes belonging to the single family of this division,
+<i>Gobiesocidæ</i>, are strictly marine but littoral fishes. They
+are scattered over the temperate zones of both hemispheres, and more
+numerous than between the Tropics. All are of small or very small size.</p>
+
+  <div class="figcenter" id="fig232" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig232.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 232.—Gobiesox cephalus.</p>
+  </div>
+
+<p>The adhesive disk consists of an anterior and posterior division.
+In some of the genera the posterior division has no free anterior
+margin, the teeth being either all conical, as in <i>Chorisochismus</i>
+(Cape of Good Hope) and <i>Cotylis</i> (Red Sea<span class="pagenum" id="Page_513">[513]</span> and Indian Ocean);
+or incisor-like in both jaws, as in <i>Sicyases</i> (coast of
+Chili and West Indies); or incisor-like at least in the lower jaw,
+as in <i>Gobiesox</i> (West Indies and Pacific coasts of South
+America). In other genera the posterior portion of the adhesive
+disk has a free anterior margin. Only one of these genera has
+incisor-like teeth, viz. <i>Diplocrepis</i> from New Zealand. In
+the remaining genera, <i>Crepidogaster</i> (from Tasmania and
+South Australia), <i>Trachelochismus</i> (from New Zealand and the
+Fiji Islands), <i>Lepadogaster</i>, and <i>Leptopterygius</i>, the
+teeth are very small and fine. The two last genera are European,
+and <i>Lepadogaster</i> at least is common on the Southern British
+coasts. The three species known as British—<i>L. gouanii</i>, <i>L.
+candollii</i>, and <i>L. bimaculatus</i>—are prettily coloured, but
+subject to great variation.</p>
+
+  <div class="figcenter" id="fig233">
+     <img
+    class="p1"   
+    src="images/fig233.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 233.—Diplocrepis puniceus.</p>
+  </div>
+
+
+<h5 class="smcap">Fifteenth Division—Acanthopterygii Channiformes.</h5>
+
+<p><i>Body elongate, covered with scales of moderate size; no spine in any
+of the fins; dorsal and anal long. No superbranchial organ, only a bony
+prominence on the anterior surface of the hyomandibular.</i></p>
+
+<p>These fishes belong to the single family <i>Ophiocephalidæ</i>,
+Freshwater-fishes characteristic of the Indian region, which, however,
+have found their way into Africa, where they are represented by one or
+two species. Thirty-one species are known altogether, most of which
+are extremely abundant; some attain to a length of more than two feet.
+Like other<span class="pagenum" id="Page_514">[514]</span> tropical freshwater fishes, they are able to survive
+droughts, living in semi-fluid mud, or lying in a torpid state below
+the hard-baked crusts of the bottom of a tank from which every drop
+of water has disappeared. Respiration is probably entirely suspended
+during the state of torpidity, but whilst the mud is still soft enough
+to allow them to come to the surface, they rise at intervals to take in
+a quantity of air, by means of which their blood is oxygenised. This
+habit has been observed in some species to continue also to the period
+of the year in which the fish lives in normal water, and individuals
+which are kept in a basin and prevented from coming to the surface
+and renewing the air for respiratory purposes, are suffocated. The
+particular manner in which the accessory branchial cavity participates
+in respiratory functions is not known. It is a simple cavity, without
+an accessory branchial organ, the opening of which is partly closed by
+a fold of the mucous membrane.</p>
+
+  <div class="figcenter" id="fig234">
+     <img
+    class="p1"   
+    src="images/fig234.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 234.—Ophiocephalus striatus, India.</p>
+  </div>
+
+
+<h5 class="smcap">Sixteenth Division—Acanthopterygii Labyrinthibranchii.</h5>
+
+<p><i>Body compressed, oblong or elevated, with scales of moderate size. A
+superbranchial organ in a cavity accessory to that of the gills.</i></p>
+
+
+<h6 class="smcap">First Family—Labyrinthici.</h6>
+
+<p><i>Dorsal and anal spines present, but in variable numbers; ventrals
+thoracic. Lateral line absent, or more or less distinctly interrupted.
+Gill-opening rather narrow, the gill-membranes<span class="pagenum" id="Page_515">[515]</span> of both sides
+coalescent below the isthmus, and scaly; gills four; pseudobranchiæ
+rudimentary or absent.</i></p>
+
+  <div class="figcenter" id="fig235" style="max-width: 285px">
+     <img
+    class="p1"   
+    src="images/fig235.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 235.—Superbranchial organ of Anabas.</p>
+  </div>
+
+<p>Freshwater-fishes of the Cyprinoid division of the Equatorial zone.
+They possess the faculty of being able to live for some time out of
+the water, or in thick or hardened mud, in a still greater degree than
+the fishes of the preceding family. In the accessory branchial cavity
+there is lodged a laminated organ which evidently has the function of
+assisting in the oxygenisation of the blood. In <i>Anabas</i> it is
+formed by several exceedingly thin bony laminæ, similar in form to the
+auricle, and concentrically situated one above the other, the innermost
+being the largest. The degree in which these laminæ are developed
+is dependent on age. In specimens from one inch and a half to two
+inches and a half long there are only two such laminæ, a third being
+indicated by a small protuberance at the central base of the second
+or outer laminæ. In specimens of from three to four inches in length
+the third lamina is developed, covering one-half of the second. The
+edges of all the laminæ are straight, not valanced. In specimens of
+from four to five inches a fourth lamina makes its appearance in the
+basal centre of the third lamina. The other laminæ continue to grow in
+their circumference, and their edges now become undulated and slightly
+frilled. Cuvier and Valenciennes have examined still larger specimens.
+The figure given by them and reproduced here was taken from a specimen
+six or seven inches long, and shows the superbranchial organ composed
+of six laminæ.</p>
+
+<p><span class="pagenum" id="Page_516">[516]</span></p>
+
+<p>The air-bladder of the majority of these fishes is very large,
+extending far into the tail, and, therefore, divided behind by the
+hæmal spines into two lateral portions.</p>
+
+<p>The Labyrinthici are generally of small size; they are capable of being
+domesticated, and some of them deserve particular attention on account
+of the dazzling beauty of their colours or the flavour of their flesh.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Anabas.</span>—Body compressed, oblong; præorbital and
+orbitals serrated. Small teeth in the jaws and on the vomer;
+none on the palatines. Dorsal and anal spines numerous. Lateral
+line interrupted.</p>
+</div>
+
+<p>The “Climbing Perch” (<i>A. scandens</i>) is generally distributed over
+the Indian Region, and well known from its faculty of moving for some
+distance over land, and even up inclined surfaces. In 1797 Daldorf, in
+a memoir communicated to the Linnean Society of London, mentions that
+in 1791 he had himself taken an Anabas in the act of ascending a palm
+tree which grew near a pond. The fish had reached the height of five
+feet above the water, and was going still higher. In the effort to do
+this it held on to the bark of the tree by the preopercular spines,
+bent its tail, and stuck in the spines of the anal; then released its
+head, and, raising it, took a new hold with the preoperculum higher up.
+The fish is named in the Malayan language the “Tree Climber.” It rarely
+attains a length of seven inches.</p>
+
+<p><i>Spirobranchus</i> from the Cape, and <i>Ctenopoma</i> from Tropical
+Africa, represent <i>Anabas</i> in that continent.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Polyacanthus.</span>—Body compressed, oblong; operculum
+without spines or serrature; cleft of the mouth small, more or
+less oblique, not extending beyond the vertical from the orbit,
+and little protractile. Small fixed teeth in the jaws, none on
+the palate. Dorsal and anal spines numerous; the soft dorsal
+and anal, the caudal, and the ventral, more or less elongate in
+mature specimens. Caudal rounded. Lateral line interrupted or
+absent.</p>
+</div>
+
+<p><span class="pagenum" id="Page_517">[517]</span></p>
+
+<p>This genus is represented chiefly in the East Indian Archipelago; seven
+species are known; some of them have been domesticated on account of
+the beauty of their colours, and several varieties have been produced.
+One of them is to be mentioned, as, under the name of “Paradise-fish,”
+it has been introduced into the aquaria of Europe, where it readily
+breeds. It was known already to Lacépède, and has been mentioned since
+his time in all ichthyological works as <i>Macropus viridi-auratus</i>.
+In adult males some of the rays, and especially the caudal lobes, are
+much prolonged.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Osphromenus.</span>—Body compressed, more or less elevated;
+operculum without spine or serrature. Small fixed teeth in the
+jaws, none on the palate. Dorsal spines in small or moderate
+number; anal spines in moderate or great number; ventral fins
+with the outer ray very long, filiform. Lateral line not
+interrupted or absent.</p>
+</div>
+
+  <div class="figcenter" id="fig236">
+     <img
+    class="p1"   
+    src="images/fig236.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 236.—Osphromenus olfax.</p>
+  </div>
+
+<p>To this genus belongs the celebrated “Gourami” (<i>Osphromenus
+olfax</i>), reputed to be one of the best flavoured Freshwater-fishes
+in the East-Indian Archipelago. Its original home is Java, Sumatra,
+Borneo, and several other islands; but thence it has been transported
+to, and acclimatised in, Penang, Malacca, Mauritius, and even Cayenne.
+Being an almost omnivorous fish and tenacious of life, it seems to
+recommend itself particularly for acclimatisation in other<span class="pagenum" id="Page_518">[518]</span> tropical
+countries, and specimens kept in captivity become as tame as carps. It
+attains the size of a large turbot. A second, but much smaller, species
+of this genus, <i>O. trichopterus</i>, is frequently kept in vessels
+on account of the exquisite beauty of its varying iridescent metallic
+tints; like other fishes of this family it is very pugnacious.</p>
+
+<p><i>Trichogaster</i>, a very common Bengalese fish, differs from
+<i>Osphromenus</i> in having the ventral fins reduced to a single long
+filament.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Betta.</span>—Body compressed, oblong; operculum without
+spine or serrature. Small fixed teeth in the jaws, none on the
+palate. Dorsal fin short, on the middle of the back, without any
+pungent spine; anal fin long. Ventral fin with five soft rays,
+the outer one being produced. Lateral line interrupted or absent.</p>
+</div>
+
+<p>A species of this genus (<i>B. pugnax</i>) is, on account of its
+pugnacious habits, reared by the Siamese. Cantor gives the following
+account:—“When the fish is in a state of quiet, its dull colours
+present nothing remarkable; but if two be brought together, or if
+one sees its own image in a looking-glass, the little creature
+becomes suddenly excited, the raised fins and the whole body shine
+with metallic colours of dazzling beauty, while the projected gill
+membrane, waving like a black frill round the throat, adds something
+of grotesqueness to the general appearance. In this state it makes
+repeated darts at its real or reflected antagonist. But both, when
+taken out of each other’s sight, instantly become quiet. This
+description was drawn up in 1840, at Singapore, by a gentleman who had
+been presented with several by the King of Siam. They were kept in
+glasses of water, fed with larvæ of mosquitoes, and had thus lived for
+many months. The Siamese are as infatuated with the combats of these
+fish as the Malays are with their cock-fights; and stake on the issue
+considerable sums, and sometimes their own persons and families. The
+license to exhibit fish-fights is farmed, and brings a considerable<span class="pagenum" id="Page_519">[519]</span>
+annual revenue to the King of Siam. The species abounds in the rivulets
+at the foot of the hills of Penang. The inhabitants name it ‘Pla-kat,’
+or the ‘Fighting-fish;’ but the kind kept especially for fighting is an
+artificial variety cultivated for the purpose.”</p>
+
+<p><span class="smcap">Micracanthus.</span>—This genus represents the three last-named
+genera in Africa, where it has been recently discovered in tributaries
+of the river Ogooué. It seems to differ from the Indian genera chiefly
+by its more elongate body, the structure of the fins being scarcely
+different (D. 3/7, A. 4/23, V. 1/4).</p>
+
+
+<h6 class="smcap">Second Family—Luciocephalidæ.</h6>
+
+<p><i>Body elongate, covered with scales of moderate size. Lateral line
+present. Teeth small. Gill-opening wide; pseudobranchiæ none. The
+superbranchial organ is formed by two branchial arches, which are
+dilated into a membrane. One short dorsal fin; dorsal and anal spines
+none; ventrals composed of one spine and five rays. Air-bladder
+none.</i></p>
+
+<p>A small Freshwater-fish (<i>Luciocephalus pulcher</i>), from the
+East-Indian Archipelago.</p>
+
+
+<h5 class="smcap">Seventeenth Division—Acanthopterygii lophotiformes.</h5>
+
+<p><i>Body riband shaped, with the vent near its extremity; a short anal
+behind the vent; dorsal fin as long as the body.</i></p>
+
+<p>Only one species is known of this division or family, <i>Lophotes
+cepedianus</i>. It is most probably a deep-sea fish, but does not
+descend to so great a depth as the <i>Trachypteridæ</i>, its bony and
+soft parts being well coherent. It is a scarce fish, hitherto found in
+the Mediterranean, off Madeira, and in the Sea of Japan; its length is
+known to exceed five feet. The head is elevated into a very high crest,
+and the dorsal fin commences with an exceedingly strong and long spine
+on the head. Silvery, with rose-coloured fins.</p>
+
+<p><span class="pagenum" id="Page_520">[520]</span></p>
+
+
+<h5 class="smcap">Eighteenth Division—Acanthopterygii Tæniiformes.</h5>
+
+<p><i>Body riband shaped; dorsal fin as long as the body; anal absent;
+caudal rudimentary, or not in the longitudinal axis of the fish.</i></p>
+
+  <div class="figcenter" id="fig237">
+     <img
+    class="p1"   
+    src="images/fig237.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 237.—Trachypterus tænia.</p>
+  </div>
+
+<p>The “Ribbon-fishes” are true deep-sea fishes, met with in all parts
+of the oceans, generally found when floating dead on the surface, or
+thrown ashore by the waves. Their body is like a band, specimens of
+from fifteen to twenty feet long being from ten to twelve inches deep,
+and about an inch or two broad at their thickest part. The eye is
+large and lateral; the mouth small, armed with very feeble teeth; the
+head deep and short. A high dorsal fin runs along the whole length of
+the back, and is supported by extremely numerous rays; its foremost
+portion, on the head, is detached from the rest of the fin, and
+composed of very elongate flexible spines. The anal fin is absent. The
+caudal fin (if preserved, which is rarely the case, in adult specimens)
+has an extra-axial position, being directed upwards like a fan. The
+ventrals are thoracic, either composed of several rays or reduced to a
+single<span class="pagenum" id="Page_521">[521]</span> long filament. The coloration is generally silvery, with rosy
+fins.</p>
+
+<p>When these fishes reach the surface of the water the expansion of the
+gases within their body has so loosened all parts of their muscular and
+bony system, that they can be lifted out of the water with difficulty
+only, and nearly always portions of the body and fins are broken and
+lost. The bones contain very little bony matter, are very porous, thin
+and light. At what depths Ribbon-fishes live is not known; probably
+the depths vary for different species; but although none have been
+yet obtained by means of the deep-sea dredge, they must be abundant
+at the bottom of all oceans, as dead fishes or fragments of them
+are frequently obtained. Some writers have supposed from the great
+length and narrow shape of these fishes that they have been mistaken
+for “Sea-serpents;” but as these monsters of the sea are always
+represented by those who have had the good fortune of meeting with them
+as remarkably active, it is not likely that harmless Ribbon-fishes,
+which are either dying or dead, have been the objects described as
+“Sea-serpents.”</p>
+
+  <div class="figcenter" id="fig238">
+     <img
+    class="p1"   
+    src="images/fig238.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 238.—Young Trachypterus.</p>
+  </div>
+
+<p>Young Ribbon-fishes (from two to four inches) are not rarely met with
+near the surface; they possess the most<span class="pagenum" id="Page_522">[522]</span> extraordinary development of
+fin rays observed in the whole class of fishes, some of them being
+several times longer than the body, and provided with lappet-like
+dilatations. There is no doubt that fishes with such delicate
+appendages are bred and live in depths where the water is absolutely
+quiet, as a sojourn in the disturbed water of the surface would
+deprive them at once of organs which must be of some utility for their
+preservation.</p>
+
+<p>Ribbon-fishes are divided into three genera:—</p>
+
+<p><span class="smcap">Trachypterus.</span>—In which the ventral rays are well developed,
+and composed of several more or less branched rays. Specimens of this
+genus have been taken in the Mediterranean, Atlantic, at Mauritius, and
+in the Eastern Pacific. The “Deal-fish” (<i>T. arcticus</i>) is often
+met with in the North Atlantic, and specimens are generally found after
+the equinoctial gales on the coasts of the Orkneys and North Britain.</p>
+
+<p><span class="smcap">Stylophorus.</span>—Without ventrals, and with the tail terminating
+in an exceedingly long cord-like appendage. Known from one specimen
+only, found at the beginning of this century between Cuba and
+Martinique. It is eleven inches long, and preserved in the Museum of
+the Royal College of Surgeons in London.</p>
+
+<p><i>Regalecus.</i>—Each ventral fin is reduced to a long filament,
+dilated at the extremity; caudal fin rudimentary or absent. These
+are the largest of all Ribbon-fishes, specimens being on record the
+length of which exceeded twenty feet. They have been taken in the
+Mediterranean, North and South Atlantic, Indian Ocean, and on the coast
+of New Zealand. They are frequently called “Kings of the herrings,”
+from the erroneous notion that they accompany the shoals of herrings;
+or “Oar-fishes,” from their two ventral fins, which have a dilatation
+at their extremity not unlike the blade of an oar. One or more species
+(<i>R. banksii</i>) are sometimes found on the British<span class="pagenum" id="Page_523">[523]</span> coasts, but
+they are very scarce, not more than sixteen captures having been
+recorded between the years 1759 and 1878.</p>
+
+
+<h5 class="smcap">Nineteenth Division—Acanthopterygii Notacanthiformes.</h5>
+
+<p><i>Dorsal fin short, composed of short, isolated spines, without a soft
+portion. Anal fin very long, anteriorly with many spines; ventrals
+abdominal, with more than five soft and several unarticulated rays.</i></p>
+
+<p><i>Notacanthus</i> is the most aberrant type of Acanthopterygians. Of
+the characteristics of this order the development of spines in the
+vertical fins is the only one preserved in the fishes of this genus.
+Their body is elongate, covered with very small scales; the snout
+protrudes beyond the mouth. Eyes lateral, of moderate size; dentition
+feeble. Five species are known from the Arctic Ocean, Mediterranean,
+Atlantic, and Southern Pacific. They inhabit considerable depths,
+probably from 100 to 400 fathoms, and during the “Challenger”
+expedition specimens have been obtained from an alleged depth of 1875
+fathoms.</p>
+
+
+<h4>SECOND ORDER:</h4>
+
+<p class="center smaller">ACANTHOPTERYGII PHARYNGOGNATHI.</p>
+
+<p><i>Part of the rays of the dorsal, anal, and ventral fins are
+non-articulated spines. The lower pharyngeals coalesced. Air-bladder
+without pneumatic duct.</i></p>
+
+  <div class="figcenter" id="fig239" style="max-width: 552px">
+     <img
+    class="p1"   
+    src="images/fig239.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 239.—Coalescent Pharyngeals of Scarus cretensis.
+<i>a</i>, upper; <i>b</i>, lower pharyngeals.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_524">[524]</span></p>
+
+
+<h6 class="smcap">First Family—Pomacentridæ.</h6>
+
+<p><i>Body short, compressed, covered with ctenoid scales. Dentition
+feeble; palate smooth. The lateral line does not extend to the caudal
+fin, or is interrupted. One dorsal fin, with the spinous portion as
+well developed as the soft, or more. Two, sometimes three, anal spines;
+the soft anal similar to the soft dorsal. Ventral fins thoracic, with
+one spine and five soft rays. Gills three and a half; pseudobranchiæ
+and air-bladder present. Vertebræ, twelve abdominal and fourteen
+caudal.</i></p>
+
+  <div class="figcenter" id="fig240" style="max-width: 381px">
+     <img
+    class="p1"   
+    src="images/fig240.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 240.—Dascyllus aruanus. Natural size, from the
+Indo-Pacific.</p>
+  </div>
+
+<p>The fishes of this family are marine; they resemble the Chætodonts
+with regard to their mode of life, living chiefly in the neighbourhood
+of coral formations. Like them they are beautifully coloured, the
+same patterns being sometimes reproduced in members of both families,
+proving that the development and distribution of colours is due to the
+agencies of climate, of the surroundings and of the habits of animals.
+The geographical range of the <i>Pomacentridæ</i> is co-extensive
+with that of the Chætodonts, the species being most numerous in the
+Indo-Pacific and Tropical Atlantic, a few extending northwards to the
+Mediterranean and Japan, southwards<span class="pagenum" id="Page_525">[525]</span> to the coasts of South Australia.
+They feed chiefly on small marine animals, and such as have compressed
+teeth appear to feed on the small Zoophytes covering the banks, round
+which these “Coral-fishes” abound. In a fossil state this family is
+known from a single genus only, <i>Odonteus</i>, from Monte Bolca,
+allied to <i>Heliastes</i>. The recent genera belonging to this
+family are:—<i>Amphiprion</i>, <i>Premnas</i>, <i>Dascyllus</i>,
+<i>Lepidozygus</i>, <i>Pomacentrus</i>, <i>Glyphidodon</i>,
+<i>Parma</i>, and <i>Heliastes</i>. About 120 species are known.</p>
+
+
+<h6 class="smcap">Second Family—Labridæ.</h6>
+
+<p><i>Body oblong or elongate, covered with cycloid scales. The lateral
+line extends to the caudal, or is interrupted. One dorsal fin, with the
+spinous portion as well developed as, or more than, the soft. The soft
+anal similar to the soft dorsal. Ventral fins thoracic, with one spine
+and five soft rays. Palate without teeth. Branchiostegals five or six;
+gills three and a half; pseudobranchiæ and air-bladder present. Pyloric
+appendages none; stomach without cæcal sac.</i></p>
+
+  <div class="figcenter" id="fig241" style="max-width: 275px">
+     <img
+    class="p1"   
+    src="images/fig241.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 241.—Lips of a Wrasse, <i>Labrus festivus</i>.</p>
+  </div>
+
+<p>The “Wrasses” are a large family of littoral fishes, very abundant in
+the temperate and tropical zones, but becoming scarcer towards the
+Arctic and Antarctic circles, where they disappear entirely. Many of
+them are readily recognised by their thick lips, which are sometimes
+internally folded, a peculiarity which has given to them the German
+term of “Lip-fishes.” They feed chiefly on mollusks and crustaceans,
+their dentition being admirably adapted for crushing hard substances.
+Many species have a strong curved tooth at the posterior extremity of
+the intermaxillary, for the purpose of pressing a shell against<span class="pagenum" id="Page_526">[526]</span> the
+lateral and front teeth by which it is crushed. Other Wrasses feed on
+corals, others on zoophytes; a few are herbivorous. In all Wrasses
+the upper pharyngeal bones seem to be jointed to the basi-occipital;
+but whilst in <i>Labrus</i> the basi-occipital is raised on each side
+into a large flattish condyle, fitting into a concavity of the upper
+pharyngeals, in <i>Scarus</i> the mode of articulation is reversed,
+the basi-occipital having a pair of long grooves, in which the oblong
+condyles of the upper pharyngeals slide forwards and backwards.
+Beautiful colours prevail in this family, permanent pigmentary colours
+as well as passing iridescent reflections of the scales. Some species
+remain very small, others grow to a weight of fifty pounds. The larger
+kinds especially are prized as food, the smaller less so.</p>
+
+<p>Remains of Labridæ, recognised by their united pharyngeals, which
+bear molar-like teeth, are not scarce in tertiary formations of
+France, Germany, Italy, and England. Such remains from Monte Bolca
+and the Swiss Molasse have been referred to the genus <i>Labrus</i>.
+Others, <i>Nummopalatus</i> and <i>Phyllodus</i>, are allied, but
+cannot be assigned, to one of the recent genera; the latter genus is
+first represented in cretaceous formations of Germany. Another genus,
+<i>Taurinichthys</i>, from the Miocene of France, represents the
+<i>Odacina</i> of the living fauna. <i>Egertonia</i>, from the Isle
+of Sheppey, differs so much from all recent Labroid genera that its
+pertinence to this family appears doubtful.</p>
+
+<div class="blockquot">
+
+<p>[See <i>J. Cocchi</i>, Monografia dei Pharyngodopilidæ, 1866;
+and <i>E. Sauvage</i>, Sur le genre Nummopalatus, in Bull. Soc.
+Geol. France, 1875.]</p>
+</div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Labrus.</span>—Body compressed, oblong, covered with scales
+of moderate size, in more than forty transverse series; snout
+more or less pointed; imbricate scales on the cheeks and
+opercles; none or only a few on the interoperculum. Teeth in
+the jaws conical, in a single series. Dorsal spines numerous,
+thirteen or twenty-one, none of which are prolonged; anal spines
+three. Lateral line not interrupted.</p>
+</div>
+
+<p><span class="pagenum" id="Page_527">[527]</span></p>
+
+<p>Young “Wrasses” differ from mature specimens in having the præoperculum
+serrated. The headquarters of this genus are the Mediterranean, whence
+it ranges, gradually diminishing towards the north, along all the
+shores of Europe. Nine species are known; British are the “Ballan
+Wrasse” (<i>L. maculatus</i>), and the “Striped or Red Wrasse” or
+“Cook” (<i>L. mixtus</i>). The two sexes of the latter species are very
+differently coloured; the male being generally ornamented with blue
+streaks, or a blackish band along the body, whilst the female has two
+or three large black blotches across the back of the tail.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Crenilabrus</span> are Labrus with serrated præoperculum; the
+number of their dorsal spines varies from thirteen to eighteen,
+and the scales are arranged in less than forty transverse series.</p>
+</div>
+
+<p>The range of this genus is co-extensive with <i>Labrus</i>. <i>C.
+melops</i>, the “Gold-sinny,” or “Cork-wing,” is common on the British
+coasts.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Tautoga.</span>—Body compressed, oblong, covered with small
+scales; scales on the cheek rudimentary, opercles naked. Teeth
+in the jaws conical, in double series; no posterior canine
+tooth. Dorsal spines seventeen, anal spines three. Lateral line
+not interrupted.</p>
+</div>
+
+<p>The “Tautog,” or “Black-fish,” is common on the Atlantic coasts of
+temperate North America, and much esteemed as food.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ctenolabrus.</span>—Body oblong, covered with scales of
+moderate size; imbricate scales on the cheeks and opercles.
+Teeth in the jaws in a band, with an outer series of stronger
+conical teeth; no posterior canine tooth. Dorsal spines from
+sixteen to eighteen; anal spines three. Lateral line not
+interrupted.</p>
+</div>
+
+<p>Four species, from the Mediterranean and the temperate parts of the
+North Atlantic, <i>Ct. rupestris</i> being common on the British, and
+<i>Ct. burgall</i> on the North American coasts.</p>
+
+<p><span class="pagenum" id="Page_528">[528]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acantholabrus.</span>—A Wrasse with five or six anal spines,
+and with the teeth in a band.</p>
+</div>
+
+<p>From the Mediterranean and British coasts (<i>A. palloni</i>).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Centrolabrus.</span>—Wrasses with four or five anal spines,
+and with the teeth in a single series.</p>
+</div>
+
+<p>Two species are known from Madeira and the Canary Islands, and one from
+northern Europe and Greenland. The latter is scarce on the British
+coasts, but bears a distinct name on the south coast, where it is
+called “Rock-cook.”</p>
+
+<p><span class="smcap">Lachnolaemus</span> from the West Indies, and <span class="smcap">Malacopterus</span>
+from Juan Fernandez, are Labroids, closely allied to the preceding
+North Atlantic genera.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cossyphus.</span>—Body compressed, oblong, with scales of
+moderate size; snout more or less pointed; imbricate scales on
+the cheeks and opercles; basal portion of the vertical fins
+scaly. Lateral line not interrupted. Teeth in the jaws in a
+single series; four canine teeth in each jaw anteriorly; a
+posterior canine tooth. Formula of the fins: D. 12/9–11, A. 3/12.</p>
+</div>
+
+<p>Twenty species are known from the tropical zone and coasts adjoining
+it; some, like <i>G. gouldii</i> from Tasmania, attain a length of
+three or four feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chilinus.</span>—Body compressed, oblong, covered with large
+scales; lateral line interrupted; cheeks with two series of
+scales; præoperculum entire; teeth in a single series, two
+canines in each jaw; no posterior canine tooth; lower jaw not
+produced backwards. Dorsal spines subequal in length; formula of
+the fins: D. 9–10/10–9, A. 3/8.</p>
+</div>
+
+<p>Common in the tropical Indo-Pacific, whence more than twenty species
+are known. Hybrids between the different species of this genus are not
+uncommon.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Epibulus.</span>—Closely allied to the preceding genus, but
+with a very protractile mouth, the ascending branches of the
+intermaxillaries, the mandibles, and the tympanic being much
+prolonged.</p>
+</div>
+
+<p><span class="pagenum" id="Page_529">[529]</span></p>
+
+<p>This fish (<i>E. insidiator</i>) is said to seize marine animals by
+suddenly thrusting out its mouth and engulphing those that come within
+the reach of the elongated tube. It attains a length of twelve inches,
+is common in the tropical Indo-Pacific, and varies much in coloration.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Anampses.</span>—Distinguished by its singular dentition, the
+two front teeth of each jaw being prominent, directed forwards,
+compressed, with cutting edge. D. 9/12, A. 3/12.</p>
+</div>
+
+<p>Beautifully coloured fishes from the tropical Indo-Pacific. Ten species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Platyglossus.</span>—Scales in thirty or less transverse
+series; lateral line not interrupted. A posterior canine tooth.
+Dorsal spines nine.</p>
+</div>
+
+<p>Small beautifully coloured Coral-fishes, abundant in the equatorial
+zone and the coasts adjoining it. Some eighty species are known
+(inclusive of the allied genera <i>Stethojulis</i>, <i>Leptojulis</i>,
+and <i>Pseudojulis</i>).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Novacula.</span>—Body strongly compressed, oblong, covered
+with scales of moderate size; head compressed, elevated, obtuse,
+with the supero-anterior profile more or less parabolic; head
+nearly entirely naked. Lateral line interrupted. No posterior
+canine tooth. D. 9/12, A. 3/12; the two anterior dorsal spines
+sometimes remote or separate from the others.</p>
+</div>
+
+<p>Twenty-six species are known from the tropical zone, and the warmer
+parts of the temperate zones. They are readily recognised by their
+compressed, knife-shaped body, and peculiar physiognomy; they scarcely
+exceed a length of twelve inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Julis.</span>—Scales of moderate size; lateral line not
+interrupted. Head entirely naked. Snout of moderate extent, not
+produced; no posterior canine tooth. Dorsal spines ten.</p>
+</div>
+
+<p>Co-extensive with <i>Platyglossus</i> in their geographical
+distribution, and of like beautiful coloration and similar habits. Some
+of the most common fishes of the Indo-Pacific, as <i>J. lunaris</i>,
+<i>trilobata</i>, and <i>dorsalis</i>, belong to this genus.</p>
+
+<p><span class="pagenum" id="Page_530">[530]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Coris.</span>—Scales small, in fifty or more transverse
+series; lateral line not interrupted. Head entirely naked.
+Dorsal spines nine.</p>
+</div>
+
+<p>Twenty-three species, distributed like <i>Platyglossus</i>; two reach
+the south coast of England, <i>Coris julis</i> and <i>C. giofredi</i>,
+said to be male and female of the same species. Some belong to the most
+gorgeously coloured kinds of the whole class of fishes.</p>
+
+<p>Genera allied to the preceding Labroids are—<i>Choerops</i>,
+<i>Xiphochilus</i>, <i>Semicossyphus</i>, <i>Trochocopus</i>,
+<i>Decodon</i>, <i>Pteragogus</i>, <i>Clepticus</i>,
+<i>Labrichthys</i>, <i>Labroides</i>, <i>Duymæria</i>,
+<i>Cirrhilabrus</i>, <i>Doratonotus</i>, <i>Pseudochilinus</i>,
+<i>Hemigymnus</i>, <i>Gomphosus</i>, <i>Cheilio</i>, and
+<i>Cymolutes</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pseudodax.</span>—Scales of moderate size; lateral line
+continuous; cheeks and opercles scaly. Each jaw armed with two
+pairs of broad incisors, and with a cutting lateral edge; teeth
+of the lower pharyngeal confluent, pavement-like. Dorsal spines
+eleven.</p>
+</div>
+
+<p>One species (<i>P. moluccensis</i>) from the East Indian Archipelago.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scarus.</span>—Jaws forming a sharp beak, the teeth being
+soldered together. The lower jaw projecting beyond the upper.
+A single series of scales on the cheek; dorsal spines stiff,
+pungent; the upper lip double in its whole circuit. The
+dentigerous plate of the lower pharyngeal is broader than long.</p>
+</div>
+
+<p>The fishes of this genus, and the three succeeding, are known by
+the name of “Parrot-wrasses.” Of <i>Scarus</i> one species (<i>S.
+cretensis</i>) occurs in the Mediterranean, and nine others in the
+tropical Atlantic. The first was held in high repute by the ancients,
+and Aristotle has several passages respecting its rumination. It was
+most plentiful and of the best quality in the Carpathian Sea, between
+Crete and Asia Minor, but was not unknown even in early times on the
+Italian coasts, though Columella says that it seldom passed beyond
+Sicily in his day. But in the reign of Claudius, according to Pliny,
+Optatus Elipentius brought it<span class="pagenum" id="Page_531">[531]</span> from the Troad, and introduced it into
+the sea between Ostium and Campagna. For five years all that were
+caught in the nets were thrown into the sea again, and from that
+time it was an abundant fish in that locality. In the time of Pliny
+it was considered to be the first of fishes <i>(Nunc Scaro datur
+principatus</i>); and the expense incurred by Elipentius was justified,
+in the opinion of the Roman gourmands, by the extreme delicacy of the
+fish. It was a fish, said the poets, whose very excrements the gods
+themselves were unwilling to reject. Its flesh was tender, agreeable,
+sweet, easy of digestion, and quickly assimilated; yet if it happened
+to have eaten an Aplysia, it produced violent diarrhœa. In short,
+there is no fish of which so much has been said by ancient writers. In
+the present day the Scarus of the Archipelago is considered to be a
+fish of exquisite flavour; and the Greeks still name it <i>Scaro</i>,
+and eat it with a sauce made of its liver and intestines. It feeds
+on fucus; and Valenciennes thinks that the necessity for masticating
+its vegetable diet thoroughly, and the working of it with that intent
+backwards and forwards in the mouth, may have given rise to the notion
+of its being a ruminant; and it is certain that its aliment is very
+finely divided when it reaches the stomach.</p>
+
+  <div class="figcenter" id="fig242">
+     <img
+    class="p1"   
+    src="images/fig242.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 242.—Scarichthys auritus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scarichthys.</span>—Differing from <i>Scarus</i> only in
+having flexible dorsal spines.</p>
+</div>
+
+<p>Two species from the Indo-Pacific.</p>
+
+<p><span class="pagenum" id="Page_532">[532]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Callyodon.</span>—Differing from <i>Scarichthys</i> in having
+the upper lip double posteriorly only.</p>
+</div>
+
+<p>Nine species from the tropical zone.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pseudoscarus.</span>—Jaws forming a strong beak, the teeth
+being soldered together. The upper jaw projecting beyond
+the lower. Two or more series of scales on the cheek. The
+dentigerous plate of the lower pharyngeal longer than broad.</p>
+</div>
+
+<p>This tropical genus contains by far the greatest number of Scaroid
+Wrasses, some seventy species being known, and a still greater number
+of names being introduced into the various Ichthyological works. They
+are beautifully coloured, but the colours change with age, and vary
+in an extraordinary degree in the same species. They rapidly fade
+after death, so that it is almost impossible to recognise in preserved
+specimens the species described from living individuals. Many attain
+to a rather large size, upwards of three feet in length. The majority
+are eaten, but some acquire poisonous properties from their food, which
+consists either of corals or of fucus.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Odax.</span>—The edge of each jaw is sharp, without distinct
+teeth. The dentigerous plate of the lower pharyngeal triangular,
+much broader than long. Cheeks and opercles scaly; scales of
+the body small or rather small; lateral line continuous. Snout
+conical. Dorsal spines rather numerous, flexible.</p>
+</div>
+
+  <div class="figcenter" id="fig243">
+     <img
+    class="p1"   
+    src="images/fig243.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 243.—Odax radiatus.</p>
+  </div>
+
+<p>Six species from the coasts of Australia and New Zealand. Small. The
+species figured (<i>O. radiatus</i>) is from Western Australia.</p>
+
+<p><span class="pagenum" id="Page_533">[533]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Coridodax.</span>—Jaws as in <i>Odax</i>, head naked. Scales
+of the body small; lateral line continuous. Snout of moderate
+extent. Dorsal spines numerous, flexible.</p>
+</div>
+
+<p>The “Butter-fish,” or “Kelp-fish” of the colonists of New Zealand
+(<i>C. pullus</i>), is prized as food, and attains to a weight of four
+or five pounds. It feeds on zoophytes, scraping them from the surface
+of the kelp, with its curiously formed teeth. Its bones are green, like
+those of <i>Belone</i>.</p>
+
+<p><span class="smcap">Olistherops</span>, from King George’s Sound, has scales of moderate
+size, but agrees otherwise with <i>Coridodax</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Siphonognathus.</span>—Head and body very elongate, snout
+long, as in <i>Fistularia</i>; upper jaw terminating in a long,
+pointed, skinny appendage; opercles and cheeks scaly; scales of
+moderate size; lateral line continuous. Dorsal spines numerous,
+flexible. Jaws as in <i>Odax</i>; the dentigerous plate of the
+lower pharyngeal very narrow.</p>
+</div>
+
+<p><i>S. argyrophanes</i>, from King George’s Sound, is the most aberrant
+type of Wrasses, whose principal characters are retained, but united
+with a form of the body which resembles that of a Pipe-fish.</p>
+
+
+<h6 class="smcap">Third Family—Embiotocidæ.</h6>
+
+<p><i>Body compressed, elevated or oblong, covered with cycloid scales;
+lateral line continuous. One dorsal fin, with a spinous portion, and
+with a scaly sheath along the base, which is separated by a groove from
+the other scales; anal with three spines and numerous rays; ventral
+fins thoracic, with one spine and five rays. Small teeth in the jaws,
+none on the palate. Pseudobranchiæ present. Stomach siphonal, pyloric
+appendages none. Viviparous.</i></p>
+
+<p>Marine Fishes characteristic of the fauna of the temperate North
+Pacific, the majority living on the American side, and only a few
+on the Asiatic. All are viviparous (see Fig. <a href="#fig70">70</a>, p. 159). Agassiz
+describes the development of the embryoes<span class="pagenum" id="Page_534">[534]</span> as a normal ovarian
+gestation, the sac containing the young not being the oviduct but
+the ovarian sheath, which fulfils the functions of the ovary. This
+organ presents two modes of arrangement: in one there is a series of
+triangular membranous flaps communicating with each other, between
+which the young are arranged, mostly longitudinally, the head of one
+to the tail of another, but sometimes with the bodies curved, to the
+number of eighteen or twenty; in the other, the cavity is divided by
+three membranes converging to a point, into four compartments, not
+communicating with each other except towards the genital opening, the
+young being arranged in the same longitudinal manner. The proportionate
+size of the young is very remarkable. In a female specimen 10½ inches
+long, and 4½ inches high, the young were nearly 3 inches long and 1
+inch high. Seventeen species are known, the majority of which belong to
+<i>Ditrema</i>, and one to <i>Hysterocarpus</i>. They do not attain to
+a large size, varying from three-quarters to three pounds in weight.</p>
+
+
+<h6 class="smcap">Fourth Family—Chromides.</h6>
+
+<p><i>Body elevated, oblong or elongate, scaly, the scales being generally
+ctenoid. Lateral line interrupted or nearly so. One dorsal fin, with a
+spinous portion; three or more anal spines; the soft anal similar to
+the soft dorsal. Ventral fins thoracic, with one spine and five rays.
+Teeth in the jaws small, palate smooth. Pseudobranchiæ none. Stomach
+coecal; pyloric appendages none.</i></p>
+
+<p>Freshwater-fishes of rather small size from the tropical parts of
+Africa and America; one genus from Western India. The species with
+lobate teeth, and with many circumvolutions of the intestines, are
+herbivorous, the other carnivorous.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Etroplus.</span>—Body compressed, elevated, covered with
+ctenoid scales of moderate size. Lateral line indistinct. Dorsal
+and anal<span class="pagenum" id="Page_535">[535]</span> spines numerous. Teeth compressed, lobate, in one or
+two series. Anterior prominences of the branchial arches not
+numerous, short, conical, hard. Dorsal fin not scaly.</p>
+</div>
+
+<p>Two species from Ceylon and Southern India.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chromis.</span>—Body compressed, oblong, covered with cycloid
+scales of moderate size. Dorsal spines numerous, anal spines
+three. Teeth compressed, more or less lobate, in one series.
+Anterior prominences of the branchial arches short, thin,
+lamelliform, non-serrated. Dorsal fin not scaly.</p>
+</div>
+
+<p>Some twenty species are known from the fresh waters of Africa and
+Palestine; the most celebrated is the “Bulti,” or “Bolty,” of the Nile,
+one of the few well-flavoured fishes of that river; it grows to the
+length of twenty inches. Two or three species of this genus occur in
+the Jordan and Lake of Galilee.</p>
+
+  <div class="figcenter" id="fig244" style="max-width: 664px">
+     <img
+    class="p1"   
+    src="images/fig244.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 244.—<i>Chromis andreæ</i>, from the Lake of Galilee.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hemichromis</span>, differing from <i>Chromis</i> in having
+conical teeth in one or two series.</p>
+</div>
+
+<p>Ten species, the range of which is co-extensive with that of
+<i>Chromis</i>. One species, <i>H. sacra</i>, is abundant in the Lake
+of Galilee.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Paretroplus</span>, differing from <i>Hemichromis</i> in
+having nine anal spines.</p>
+</div>
+
+<p>One species from Madagascar.</p>
+
+<p><span class="pagenum" id="Page_536">[536]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acara.</span>—Body compressed, oblong, covered with ctenoid
+scales of moderate size. Dorsal spines numerous, anal spines
+three or four; base of the soft dorsal nearly uncovered by
+scales. Teeth in a band, small, conical. Anterior prominences of
+the first branchial arch very short tubercles.</p>
+</div>
+
+<p>Some twenty species are known from the fresh waters of Tropical
+America, <i>A. bimaculata</i> being one of the most common fishes of
+that region. All are very small.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Heros.</span>—Differing from <i>Acara</i> in having more than
+four anal spines.</p>
+</div>
+
+<p>Some fifty species are known from the fresh waters of Tropical America,
+especially Central America, where almost every large lake or river is
+tenanted by one or more peculiar species. They are of rather small
+size, rarely exceeding a length of twelve inches.</p>
+
+  <div class="figcenter" id="fig245" style="max-width: 676px">
+     <img
+    class="p1"   
+    src="images/fig245.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 245.—<i>Heros salvini</i>, from Central America.</p>
+  </div>
+
+<p>Genera allied to <i>Heros</i>, and likewise from Tropical America, are
+<i>Neetroplus</i>, <i>Mesonauta</i>, <i>Petenia</i>, <i>Uaru</i>, and
+<i>Hygrogonus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cichla.</span>—Form of the body perch-like. Scales small;
+the spinous and soft portions of the dorsal fin of nearly equal
+extent, and separated by a notch; anal spines three. Each jaw
+with a broad band of villiform teeth. The outer branchial arch
+with lanceolate crenulated prominences along its concave side.
+Dorsal and anal fins scaly.</p>
+</div>
+
+<p>Four species from Brazil, Guyana, and Peru.</p>
+
+<p><span class="pagenum" id="Page_537">[537]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Crenicichla.</span>—Body low, sub-cylindrical; scales small
+or rather small. The spinous portion of the dorsal is much
+more developed than the soft, both being continuous, and not
+separated by a notch; anal spines three. Præopercular margin
+serrated. Each jaw with a band of conical teeth. The outer
+branchial arch with short tubercles. Dorsal and anal fins naked.</p>
+</div>
+
+<p>Ten species from Brazil and Guyana.</p>
+
+<p>The following genera complete the list of South American Chromides:
+<i>Chætobranchus</i>, <i>Mesops</i>, <i>Satanoperca</i>,
+<i>Geophagus</i>, <i>Symphysodon</i>, and <i>Pterophyllum</i>.</p>
+
+
+<h4>THIRD ORDER—ANACANTHINI.</h4>
+
+<p><i>Vertical and ventral fins without spinous rays. The ventral fins,
+if present, are jugular or thoracic. Air-bladder, if present, without
+pneumatic duct.</i></p>
+
+<p>These characters are common to all the members of this order, with
+the exception of a freshwater-fish from Tasmania and South Australia
+(<i>Gadopsis</i>), which has the anterior portion of the dorsal and
+anal fins formed of spines.</p>
+
+
+<h5 class="smcap">First Division—Anacanthini Gadoidei.</h5>
+
+<p><i>Head and body symmetrically formed.</i></p>
+
+
+<h6 class="smcap">First Family—Lycodidæ.</h6>
+
+<p><i>Vertical fins confluent. Ventral fin, if present, small, attached to
+the humeral arch, jugular. Gill-opening narrow, the gill-membrane being
+attached to the isthmus.</i></p>
+
+<p>Marine littoral fishes of small size, resembling Blennies, chiefly
+represented in high latitudes, but a few living within the tropical
+zone.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lycodes.</span>—Body elongate, covered with minute scales
+imbedded in the skin, or naked; lateral line more or less
+indistinct. Eye of moderate size. Ventral small, short,
+rudimentary, jugular,<span class="pagenum" id="Page_538">[538]</span> composed of several rays. Upper jaw
+overlapping the lower. Conical teeth in the jaws, on the
+vomer, and on the palatine bones. Barbel none. Five or six
+branchiostegals; gill-opening narrow, the gill-membranes being
+attached to the isthmus. Pseudobranchiæ present. Air-bladder
+none. Pyloric appendages two, or rudimentary, or entirely
+absent. No prominent anal papilla.</p>
+</div>
+
+  <div class="figcenter" id="fig246">
+     <img
+    class="p1"   
+    src="images/fig246.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 246.—Lycodes mucosus, from Northumberland Sound.</p>
+  </div>
+
+<p>Nine species are known from the Arctic Ocean, four from the southern
+extremity of the American continent.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gymnelis.</span>—Body elongate, naked. Eye of moderate
+size or rather small. Ventrals none. Vent situated at some
+distance backwards from the head. Small conical teeth in the
+jaws, on the vomer and palatine bones. Jaws equal anteriorly.
+Barbel none. Six branchiostegals; gill-opening narrow, the gill
+membranes being attached to the isthmus. Pseudobranchiæ present;
+air-bladder none. Pyloric appendages two; no prominent anal
+papilla.</p>
+</div>
+
+  <div class="figcenter" id="fig247">
+     <img
+    class="p1"   
+    src="images/fig247.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 247.—Gymnelis viridis.</p>
+  </div>
+
+<p>One species (<i>G. viridis</i>) from Greenland, the other (<i>G.
+pictus</i>) from the Straits of Magelhæn.</p>
+
+<p>The other genera belonging to this family are <i>Uronectes</i> from
+Baffin’s Bay, <i>Microdesmus</i> from Panama, <i>Blennodesmus</i>
+from the coast of North-Eastern Australia, and <i>Maynea</i> from the
+Straits of Magelhæn.</p>
+
+<p><span class="pagenum" id="Page_539">[539]</span></p>
+
+
+<h6 class="smcap">Second Family—Gadidæ.</h6>
+
+<p><i>Body more or less elongate, covered with small smooth scales. One,
+two, or three dorsal fins, occupying nearly the whole of the back; rays
+of the posterior dorsal well developed; one or two anal fins. Caudal
+free from dorsal and anal, or, if they are united, the dorsal with a
+separate anterior portion. Ventrals jugular, composed of several rays,
+or, if they are reduced to a filament, the dorsal is divided into two.
+Gill-opening wide; the gill-membranes generally not attached to the
+isthmus. Pseudobranchiæ none, or glandular, rudimentary. An air-bladder
+and pyloric appendages generally present.</i></p>
+
+<p>The family of “Cod-fishes” consists partly of littoral and surface
+species (and they form the majority), partly of deep-sea forms. The
+former are almost entirely confined to the temperate zones, extending
+beyond the Arctic Circle; the latter have, as deep-sea fishes
+generally, a much wider range, and hitherto have been found chiefly at
+considerable depths of rather low latitudes. Only two or three species
+inhabit fresh waters. They form one of the most important articles of
+food and subsistence to the fishermen in Europe and North America, and
+to whole tribes bordering upon the Arctic Ocean.</p>
+
+<p>Fossil remains are scarce. <i>Nemopteryx</i> and <i>Palæogadus</i> have
+been described from the schists of Glaris, a formation believed to have
+been the bottom of a very deep sea. In the clay of Sheppey species
+occur allied to <i>Gadus</i>, <i>Merluccius</i>, and <i>Phycis</i>;
+others, not readily determinable, have been found at Licata in Sicily
+(Miocene).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gadus.</span>—Body moderately elongate, covered with small
+scales. A separate caudal, three dorsal, and two anal fins;
+ventrals narrow, composed of six or more rays. Teeth in the
+upper jaw in a narrow band; vomerine teeth; none on the
+palatines.</p>
+</div>
+
+<p><span class="pagenum" id="Page_540">[540]</span></p>
+
+<p>Arctic and temperate zones of the Northern Hemisphere. Eighteen species
+are known, of which the following are the most important:—</p>
+
+<p><i>Gadus morrhua</i>, the common “Cod-fish”—in German called
+“Kabeljau” when fresh and old, “Dorsch” when young and fresh,
+“Stock-fish” when dried, “Labberdan” when salted—measures from two
+to four feet, and attains to a weight of one hundred pounds. On the
+British coasts and in the German Ocean it is generally of a greenish or
+brownish-olive colour, with numerous yellowish or brown spots. Farther
+northwards darker-coloured specimens, frequently without any spots,
+predominate; and on the Greenland, Iceland, and North Scandinavian
+coasts the Cod have often a large irregular black blotch on the side.
+The Cod-fish occurs between 50° and 75° lat. N., in great profusion,
+to a depth of 120 fathoms, but is not found nearer the Equator than
+40° lat. Close to the coast it is met with singly all the year round,
+but towards the spawning-time it approaches the shore in numbers,
+which happens in January in England and not before May on the American
+coasts. The English resorted to the cod-fisheries of Iceland before
+the year 1415, but since the sixteenth century most vessels go to
+the banks of Newfoundland, and almost all the preserved Cod consumed
+during Lent in the various continental countries is imported from
+across the Atlantic. At one time the Newfoundland cod-fishery rivalled
+in importance the whale-fishery and the fur trade of North America.
+Cod-liver oil is prepared from the liver on the Norwegian coast, but
+also other species of this genus contribute to this most important drug.</p>
+
+<p><i>Gadus tomcodus</i> abundantly occurs on the American coasts; it
+remains within smaller dimensions than the common Cod-fish. <i>Gadus
+æglefinus</i>, the “Haddock” (“Schell-fisch” of the Germans, “Hadot” of
+the French), is distinguished by a black lateral line and a blackish
+spot above the pectoral fin. It<span class="pagenum" id="Page_541">[541]</span> attains to a length of three feet in
+the higher latitudes, but remains smaller on more southern coasts;
+like the Cod it extends across the Atlantic. The largest specimens are
+taken on the British coast in winter, because at that time they leave
+the deep water to spawn on the coast. <i>Gadus merlangus</i>, the
+“Whiting,” with a black spot in the axil of the pectoral fin. <i>Gadus
+luscus</i>, the “Bib,” “Pout,” or “Whiting-pout,” with cross-bands
+during life, and with a black axillary spot, rarely exceeding a weight
+of five pounds. <i>Gadus fabricii</i>, a small species, but occurring
+in incredible numbers on the shores near the Arctic circle, and ranging
+to 80° lat. N. <i>Gadus pollachius</i>, the “Pollack,” without a barbel
+at the chin, and with the lower jaw projecting beyond the upper.
+<i>Gadus virens</i>, the “Coal-fish,” valuable on account of its size
+and abundance, and therefore preserved for export like the Cod.</p>
+
+<p>The fishes of the genus <i>Gadus</i> are bathymetrically succeeded by
+several genera, as <i>Gadiculus</i>, <i>Mora</i>, and <i>Strinsia</i>;
+however these do not descend to sufficiently great depths to be
+included into the deep-sea Fauna; the two following are true deep-sea
+fishes.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Halargyreus.</span>—Body elongate, covered with small scales.
+Two dorsal and two anal fins; ventrals composed of several rays.
+Jaws with a band of minute villiform teeth; vomer and palatines
+toothless. No barbel.</p>
+</div>
+
+<p>The single species known, <i>H. johnsonii</i>, proves to be a deep-sea
+fish by its organisation as well as geographical distribution.
+Originally known from a single specimen, which was obtained at Madeira,
+it has since been found off the coast of New Zealand. There is no doubt
+that it will be discovered also in intermediate seas.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Melanonus.</span>—Head and body rather compressed, covered
+with cycloid scales of moderate size, and terminating in a long
+tapering tail, without caudal. Eye of moderate size. Villiform
+teeth in the jaws, on the vomer and palatine bones. Barbel<span class="pagenum" id="Page_542">[542]</span>
+none. A short anterior dorsal, the second extending to the end
+of the tail, and the anal being of similar length. Ventrals
+composed of several rays. Bones soft and flexible.</p>
+</div>
+
+<p>This is one of the discoveries made during the expedition of the
+“Challenger.” The single specimen obtained is of a deep-black colour,
+and was dredged up at a depth of 1975 fathoms in the Antarctic Ocean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Merluccius.</span>—Body elongate, covered with very small
+scales. A separate caudal; two dorsal fins and one anal;
+ventrals well developed, composed of seven rays. Teeth in the
+jaws and on the vomer rather strong, in double or triple series.
+No barbel.</p>
+</div>
+
+<p>Two species are known of this genus, widely separated in their
+distribution. The European species, <i>M. vulgaris</i>, the “Hake,”
+is found on both sides of the Atlantic, and grows to a length of four
+feet. It is caught in great numbers, and preserved as “Stock-fish.” The
+second species <i>M. gayi</i>, is common in the Straits of Magelhæn and
+on the coast of Chili, less so in New Zealand.</p>
+
+<p>The vertebral column of this genus shows a singular modification of
+the apophyses. The neural spines of all the abdominal vertebræ are
+extremely strong, dilated, wedged into one another. The parapophyses
+of the third to sixth vertebræ are slender, styliform, whilst those of
+all the following abdominal vertebræ are very long and broad, convex on
+the upper and concave on the lower surface; the two or three anterior
+pairs are, as it were, inflated. The whole forms a strong roof for the
+air-bladder, reminding us of a similar structure in <i>Kurtus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pseudophycis.</span>—Body of moderate length, covered with
+rather small scales. A separate caudal, two dorsals, and one
+anal; ventral fins very narrow and styliform, but composed
+of several rays. Jaws with a band of small teeth; vomer and
+palatines toothless. Chin with a barbel.</p>
+</div>
+
+<p>Two species, of which <i>Ps. bachus</i> is common on the coast of New
+Zealand.</p>
+
+<p><span class="pagenum" id="Page_543">[543]</span></p>
+
+<p>Allied genera are <i>Lotella</i>, <i>Physiculus</i>, <i>Uraleptus</i>,
+and <i>Læmonema</i>, from moderate depths, obtained chiefly off Madeira
+and the Southern Temperate Zone.</p>
+
+  <div class="figcenter" id="fig248">
+     <img
+    class="p1"   
+    src="images/fig248.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 248.—Pseudophycis bachus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Phycis.</span>—Body of moderate length, covered with small
+scales. Fins more or less enveloped in loose skin. A separate
+caudal; two dorsal fins and one anal; the anterior dorsal
+composed of from eight to ten rays; ventrals reduced to a single
+long ray, bifid at its end. Small teeth in the jaws and on the
+vomer; palatine bones toothless. Chin with a barbel.</p>
+</div>
+
+<p>Six species from the temperate parts of the North Atlantic and the
+Mediterranean, one, <i>Ph. blennioides</i>, is occasionally found on
+the British coast.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Haloporphyrus.</span>—Body elongate, covered with small
+scales. A separate caudal, two dorsal fins, and one anal; the
+first dorsal with four rays; ventrals narrow, composed of six
+rays. Jaws and vomer with villiform teeth; palatine bones
+toothless. Chin with a barbel.</p>
+</div>
+
+<p>A small genus of deep-sea fishes, of which three species are known.
+They offer a striking instance of the extraordinary distribution of
+deep-sea fishes; <i>H. lepidion</i> occurs in from 100 to 600 fathoms
+in the Mediterranean and the neighbouring parts of the Atlantic, off
+the coast of Japan, and various parts of the South Atlantic; <i>H.
+australis</i> in from 55 to 70 fathoms in the Straits of Magelhæn; and
+finally <i>H. rostratus</i> in from 600 to 1375 fathoms, midway between
+the Cape of Good Hope and Kerguelen’s Land, and in the South Atlantic.</p>
+
+<p><span class="pagenum" id="Page_544">[544]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Lota.</span>—Body elongate, covered with very small scales. A
+separate caudal, two dorsal fins, and one anal; ventrals narrow,
+composed of six rays. Villiform teeth in the jaws and on the
+vomer; none on the palatines. The first dorsal with from ten to
+thirteen well-developed rays. Chin with a barbel.</p>
+</div>
+
+<p>The “Burbot,” or “Eel-pout” (<i>L. vulgaris</i>, Fig. <a href="#fig8">8</a>, p. 43),
+is a Freshwater-fish which never enters salt water. It is locally
+distributed in Central and Northern Europe and North America; it is one
+of the best Freshwater-fishes, and exceeds a length of three feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Molva.</span>—Differs from Lota in having several large teeth
+in the lower jaw and on the vomer.</p>
+</div>
+
+<p>The “Ling” (<i>M. vulgaris</i>) is a very valuable species, common on
+the northern coasts of Europe, Iceland, and Greenland; and generally
+found from three to four feet long. The larger number of the specimens
+caught are cured and dried.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Motella.</span>—Body elongate, covered with minute scales.
+A separate caudal. Two dorsal fins, the anterior of which is
+reduced to a narrow rayed fringe, more or less concealed in a
+longitudinal groove; the first ray is prolonged. One anal fin.
+Ventrals composed of from five to seven rays. A band of teeth in
+the jaws and on the vomer.</p>
+</div>
+
+<p>Eight species of “Rocklings” are known from the coasts of Europe,
+Iceland, Greenland, Japan, the Cape of Good Hope, and New Zealand. They
+are of small size, and chiefly distinguished by the number of their
+barbels. British are the Five-bearded Rockling (<i>M. mustela</i>), the
+Three-bearded Rocklings (<i>M. tricirrhata</i>, <i>macrophthalma</i>,
+and <i>maculata</i>), and the Four-bearded Rockling (<i>M.
+cimbria</i>). <i>M. macrophthalma</i> comes from a depth of from 80 to
+180 fathoms. The young are known as “Mackerel Midge” (<i>Couchia</i>),
+and sometimes met with in large numbers at some distance from the coast.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Raniceps.</span>—Head large, broad, and depressed; body
+of moderate length, covered with minute scales. A separate
+caudal.<span class="pagenum" id="Page_545">[545]</span> Two dorsal fins, the anterior of which is very short,
+rudimentary. One anal fin. Ventrals composed of six rays.
+Cardlike teeth in the jaws and on the vomer.</p>
+</div>
+
+<p>The “Trifurcated Hake,” <i>R. trifurcus</i>, not uncommon on the coasts
+of Northern Europe.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bregmaceros.</span>—Body fusiform, compressed posteriorly,
+covered with cycloid scales of moderate size. Two dorsal fins;
+the anterior reduced to a single long ray on the occiput; the
+second and the anal much depressed in the middle; ventrals very
+long, composed of five rays. Teeth small.</p>
+</div>
+
+  <div class="figcenter" id="fig249">
+     <img
+    class="p1"   
+    src="images/fig249.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 249.—Bregmaceros macclellandii.</p>
+  </div>
+
+<p>A dwarf Gadoid, the only one found at the surface between the Tropics.
+<i>B. macclellandii</i> scarcely exceeds three inches in length, is not
+uncommon in the Indian Ocean, and has found its way to New Zealand;
+specimens have been picked up in mid-ocean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Murænolepis.</span>—Body covered with lanceolate epidermoid
+productions, intersecting each other at right angles like those
+of a Freshwater-eel. Vertical fins confluent, no caudal being
+discernible; an anterior dorsal fin is represented by a single
+filamentous ray; ventral fins narrow, composed of several rays.
+A<span class="pagenum" id="Page_546">[546]</span> barbel. Jaws with a band of villiform teeth; palate toothless.</p>
+</div>
+
+<p>One species (<i>M. marmoratus</i>) from Kerguelen’s Land.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chiasmodus.</span>—Body naked; stomach and abdomen
+distensible. Two dorsal fins and one anal; a separate caudal;
+ventral fins rather narrow, with several rays. Upper and lower
+jaws with two series of large pointed teeth, some of the
+anterior being very large and movable; teeth on the palatine
+bones, but none on the vomer. Chin without barbel.</p>
+</div>
+
+<p>This Gadoid (<i>Ch. niger</i>, Fig. <a href="#fig111">111</a>, p. 311), inhabits great depths
+in the Atlantic (to 1500 fathoms). The specimen figured was taken with
+a large Scopeloid in its stomach.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Brosmius.</span>—Body moderately elongate, covered with very
+small scales. A separate caudal, one dorsal, and one anal;
+ventrals narrow, composed of five rays. Vomerine and palatine
+teeth. A barbel.</p>
+</div>
+
+<p>The “Torsk” (<i>B. brosme</i>) is confined to the northern parts of the
+temperate zone, and probably extends to the arctic circle.</p>
+
+
+<h6 class="smcap">Third Family—Ophidiidæ.</h6>
+
+<p><i>Body more or less elongate, naked, or scaly. Vertical fins generally
+united; no separate anterior dorsal or anal; dorsal occupying the
+greater portion of the back. Ventral fins rudimentary or absent,
+jugular. Gill-openings wide, the gill-membranes not attached to the
+isthmus.</i></p>
+
+<p>Marine fishes (with the exception of <i>Lucifuga</i>), partly littoral,
+partly bathybial. They may be divided into five groups.</p>
+
+<p>I. <i>Ventral fins present, attached to the humeral arch</i>:
+<span class="smcap">Brotulina</span>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Brotula.</span>—Body elongate, covered with minute scales.
+Eye of moderate size. Each ventral reduced to a single filament,
+sometimes bifid at its extremity. Teeth villiform; snout with
+barbels. One pyloric appendage.</p>
+</div>
+
+<p><span class="pagenum" id="Page_547">[547]</span></p>
+
+<p>Five species of small size from the Tropical Atlantic and Indian Ocean.</p>
+
+  <div class="figcenter" id="fig250" style="max-width: 539px">
+     <img
+    class="p1"   
+    src="images/fig250.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 250.—Lucifuga dentata, from caves in Cuba.</p>
+  </div>
+
+<p><i>Lucifuga</i> are <i>Brotula</i> organised for a subterranean life.
+The eye is absent, or quite rudimentary, and covered by the skin; the
+barbels of Brotula are replaced by numerous minute ciliæ or tubercles.
+They inhabit the subterranean waters of caves in Cuba, and never come
+to the light.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bathynectes.</span>—Body produced into a long tapering tail,
+without caudal. Mouth very wide, villiform teeth in the jaws, on
+the vomer and palatine bones. Barbel none. Ventral fins reduced
+to simple or bifid filaments, placed close together, and near to
+the humeral symphysis. Gill-membranes not united; gill-laminæ
+remarkably short. Bones of the head soft and cavernous;
+operculum with a very feeble spine above.</p>
+</div>
+
+<p>Deep-sea fishes, inhabiting depths varying from 1000 to 2500 fathoms.
+Three species are known, the largest specimen obtained being seventeen
+inches long.</p>
+
+  <div class="figcenter" id="fig251">
+     <img
+    class="p1"   
+    src="images/fig251.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 251.—Acanthonus armatus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acanthonus.</span>—Head large and thick, armed in front
+and on the opercles with strong spines; trunk very short, the
+vent being below the pectoral; tail thin, strongly compressed,
+tapering, without caudal. Eye small. Mouth very wide; villiform
+teeth in the jaws, on the vomer and palatine bones. Barbel
+none.<span class="pagenum" id="Page_548">[548]</span> Ventrals reduced to simple filaments placed close
+together on the humeral symphysis. Scales extremely small. Bones
+of the head soft.</p>
+</div>
+
+<p>Only two specimens, thirteen inches long, of this remarkable deep-sea
+form have been obtained, at a depth of 1075 fathoms, in the Indian
+Ocean.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Typhlonus.</span>—Head large, compressed, with most of the
+bones in a cartilaginous condition; the superficial bones with
+large muciferous cavities, not armed. Snout a thick protuberance
+projecting beyond the mouth, which is rather small and inferior.
+Trunk very short, the vent being below the pectoral; tail thin,
+strongly compressed, tapering, without separate caudal. Eye
+externally not visible. Villiform teeth in the jaws, on the
+vomer and palatine bones. Barbel none. Scales thin, deciduous,
+small.</p>
+</div>
+
+<p>Also of this deep-sea fish two specimens only are known, 10 inches
+long, from a depth of 2200 fathoms in the Western Pacific.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aphyonus.</span>—Head, body, and tapering tail strongly
+compressed, enveloped in a thin, scaleless, loose skin. Vent far
+behind the pectoral. Snout swollen, projecting beyond the wide
+mouth. No teeth in the upper jaw, small ones in the lower. No
+externally visible eye. Barbel none. Head covered with a system
+of wide muciferous channels, the dermal bones being almost
+membranaceous, whilst the others are in a semi-cartilaginous
+condition. Notochord persistent, but with a superficial
+indication of vertebral segments.</p>
+</div>
+
+  <div class="figcenter" id="fig252">
+     <img
+    class="p1"   
+    src="images/fig252.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 252.—Aphyonus gelatinosus.</p>
+  </div>
+
+<p>One specimen only of this most remarkable form is known; it is 5½
+inches long, and was obtained at a depth of 1400 fathoms south of New
+Guinea.</p>
+
+<p><span class="pagenum" id="Page_549">[549]</span></p>
+
+<p>Of the remaining genera belonging to this group, <i>Brotulophis</i>,
+<i>Halidesmus</i>, <i>Dinematichthys</i>, and <i>Bythites</i> are
+surface forms; <i>Sirembo</i> and <i>Pteridium</i> inhabit moderate
+depths; <i>Rhinonus</i> is a deep-sea fish.</p>
+
+<p>II. <i>Ventral fins replaced by a pair of bifid filaments (barbels)
+inserted below the glossohyal</i>: <span class="smcap">Ophidiinæ</span>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ophidium.</span>—Body elongate, compressed, covered with very
+small scales. Eye of moderate size. All the teeth small.</p>
+</div>
+
+<p>Small fishes from the Atlantic and Pacific. Seven species are known,
+differing from one another in the structure of the air-bladder (see p.
+145).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Genypterus</span> is a larger form of <i>Ophidium</i>, in
+which the outer series of teeth in the jaws and the single
+palatine series contains strong teeth.</p>
+</div>
+
+<p>Three species from the Cape of Good Hope, South Australia, New Zealand,
+and Chili are known. They grow to a length of five feet, and have an
+excellent flesh, like cod, well adapted for curing. At the Cape they
+are known by the name of “Klipvisch,” and in New Zealand as “Ling” or
+“Cloudy Bay Cod.”</p>
+
+<p>III. <i>No ventral fins whatever; vent at the throat</i>:
+<span class="smcap">Fierasferina</span>.</p>
+
+<p>These fishes (<i>Fierasfer</i> and <i>Encheliophis</i>) are of very
+small size and eel-like in shape; the ten species known are found in
+the Mediterranean, Atlantic, and Indo-Pacific. As far as is known they
+live parasitically in cavities of other marine animals, accompany
+Medusæ, and more especially penetrate into the respiratory cavities of
+Star-fishes and Holothurians. Not rarely they attempt other animals
+less suited for their habits, as, for instance, Bivalves; and cases are
+known in which they have been found imprisoned below the mantle of the
+Mollusk, or covered over with a layer of the pearly substance secreted
+by it. They are perfectly harmless to their<span class="pagenum" id="Page_550">[550]</span> host, and merely seek for
+themselves a safe habitation, feeding on the animalcules which enter
+with the water the cavity inhabited by them.</p>
+
+<p>IV. <i>No ventral fins whatever; vent remote from the head;
+gill-openings very wide, the gill-membranes not being united</i>:
+<span class="smcap">Ammodytina</span>.</p>
+
+<p>The “Sand-eels” or “Launces” (<i>Ammodytes</i>) are extremely common
+on sandy shores of Europe and North America. They live in large
+shoals, rising as with one accord to the surface, or diving to the
+bottom, where they bury themselves with incredible rapidity in the
+sand. They are much sought after for bait by fishermen, who discover
+their presence on the surface by watching the action of Porpoises
+which feed on them. These Cetaceans, when they meet with a shoal, know
+how to keep it on the surface by diving below and swimming round it,
+thus destroying large numbers of them. The most common species on the
+British coast is the Lesser Sand-eel (<i>A. tobianus</i>); the Greater
+Sand-eel (<i>A. lanceolatus</i>), which attains to a length of eighteen
+inches; <i>A. siculus</i>, from the Mediterranean, scarcer in British
+seas. Two species live on the American coasts, <i>A. americanus</i>
+and <i>A. dubius</i>; one in California, <i>A. personatus</i>.
+<i>Bleekeria</i> from Madras is the second genus of this group.</p>
+
+  <div class="figcenter" id="fig253">
+     <img
+    class="p1"   
+    src="images/fig253.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 253.—Congrogadus subducens.</p>
+  </div>
+
+<p>V. <i>No ventral fins whatever; vent remote from the head;
+gill-openings of moderate width, the gill-membranes being united below
+the throat, not attached to the isthmus</i>: <span class="smcap">Congrogadina</span>.</p>
+
+<p>Only two fishes belong to this group—<i>Congrogadus</i> from the
+Australian coasts, and <i>Haliophis</i> from the Red Sea.</p>
+
+<p><span class="pagenum" id="Page_551">[551]</span></p>
+
+
+<h6 class="smcap">Fourth Family—Macruridæ.</h6>
+
+<p><i>Body terminating in a long, compressed, tapering tail, covered with
+spiny, keeled, or striated scales. One short ante</i><i>rior<span class="pagenum" id="Page_552">[552]</span> dorsal;
+the second very long, continued to the end of the tail, and composed
+of very feeble rays; anal of an extent similar to that of the second
+dorsal; no caudal. Ventral fins thoracic or jugular, composed of
+several rays.</i></p>
+
+  <div class="figcenter" id="fig254" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig254.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 254.—Scale of Macrurus trachyrhynchus.</p>
+  </div>
+
+  <div class="figcenter" id="fig255" style="max-width: 280px">
+     <img
+    class="p1"   
+    src="images/fig255.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 255.—Scale of Macrurus cœlorhynchus.</p>
+  </div>
+
+  <div class="figcenter" id="fig256" style="max-width: 301px">
+     <img
+    class="p1"   
+    src="images/fig256.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 256.—Scale from the lateral line of Macrurus
+australis.</p>
+  </div>
+
+<p>This family, known a few years ago from a limited number of examples,
+representing a few species only, proves to be one which is distributed
+over all oceans, occurring in considerable variety and great abundance
+at depths of from 120 to 2600 fathoms. They are, in fact, Deep-sea
+Gadoids, much resembling each other in the general shape of their body,
+but differing in the form of the snout and in the structure of their
+scales. About forty species are known, of which many attain a length of
+three feet. They have been referred to the following genera:—</p>
+
+  <div class="figcenter" id="fig257">
+     <img
+    class="p1"   
+    src="images/fig257.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 257.—Macrurus australis.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Macrurus.</span>—Scales of moderate size; snout produced,
+conical; mouth inferior.</p>
+
+<p><span class="smcap">Coryphænoides.</span>—Scales of moderate size; snout obtuse,
+obliquely truncated; cleft of the mouth lateral.</p>
+
+<p><span class="smcap">Macruronus.</span>—Scales of moderate size, spiny; snout
+pointed; mouth anterior and lateral, with the lower jaw
+projecting.</p>
+
+<p><span class="smcap">Malacocephalus.</span>—Scales very small, ctenoid; snout
+short, obtuse, obliquely truncated.</p>
+
+<p><span class="smcap">Bathygadus.</span>—Scales small, cycloid; snout not
+projecting beyond the mouth; mouth wide, anterior, and lateral.</p>
+</div>
+
+<p><span class="pagenum" id="Page_553">[553]</span></p>
+
+<p><i>Ateleopus</i> from Japan and <i>Xenocephalus</i> from New Ireland
+are genera belonging to the Gadoid Anacanths, but are very imperfectly
+known.</p>
+
+
+<h5 class="smcap">Second Division—Anacanthini Pleuronectoidei.</h5>
+
+<p><i>Head and part of the body unsymmetrically formed.</i></p>
+
+<p>This division consists of one family only:</p>
+
+
+<h6 class="smcap">Pleuronectidæ.</h6>
+
+<p>The fishes of this family are called “Flat-fishes,” from their strongly
+compressed, high, and flat body; in consequence of the absence of
+an air-bladder, and of the structure of their paired fins, they are
+unable to maintain their body in a vertical position, resting and
+moving on one side of the body only. The side turned towards the
+bottom is sometimes the left, sometimes the right, colourless, and
+termed the “blind” side; that turned upwards and towards the light
+is variously, and in some tropical species even vividly, coloured.
+Both eyes are on the coloured side, on which side also the muscles
+are more strongly developed. The dorsal and anal fins are exceedingly
+long, without division. All the Flat-fishes undergo remarkable
+changes with age, which, however, are very imperfectly known and not
+yet fully understood, from the difficulty of referring larval forms
+to their respective parents. The larvæ are, singularly enough, much
+more frequently met in the open ocean than near the coast; they are
+transparent, like <i>Leptocephali</i>; perfectly symmetrical, with an
+eye on each side of the head, and swim in a vertical position like
+other fishes. The manner in which one eye is transferred from the blind
+to the coloured side is subject to discussion. Whilst some naturalists
+believe that the eye turning round its axis pushes its way through the
+yielding bones from the blind to the<span class="pagenum" id="Page_554">[554]</span> upper side, others hold that, as
+soon as the body of the fish commences to rest on one side only, the
+eye of that side, in its tendency to turn towards the light, carries
+the surrounding parts of the head with it; in fact, the whole of the
+fore-part of the head is twisted towards the coloured side, which is a
+process of but little difficulty as long as the framework of the head
+is still cartilaginous.</p>
+
+<p>Flat-fishes when adult live always on the bottom, and swim with an
+undulating motion of their body. Sometimes they rise to the surface;
+they prefer sandy bottom, and do not descend to any considerable depth.
+They occur in all seas, except in the highest latitudes and on rocky,
+precipitous coasts, becoming most numerous towards the equator; those
+of the largest size occur in the temperate zone. Some enter fresh water
+freely, and others have become entirely acclimatised in ponds and
+rivers. All are carnivorous.</p>
+
+<p>Flat-fishes were not abundant in the tertiary epoch; the only
+representative known is a species of <i>Rhombus</i> from Monte Bolca.</p>
+
+<p>The size and abundance of Flat-fishes, and the flavour of the flesh of
+the majority of the species, render this family one of the most useful
+to man; and especially on the coasts of the northern temperate zone,
+their capture is one of the most important sources of profit to the
+fishermen.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Psettodes.</span>—Mouth very wide, the maxillary being more
+than one-half of that of the head. Each jaw armed with two
+series of long, slender, curved, distant teeth, the front teeth
+of the inner series of the lower jaw being the longest, and
+received in a groove before the vomer; vomerine and palatine
+teeth. The dorsal fin commences on the nape of the neck.</p>
+</div>
+
+<p>This genus fitly heads the list of Flat-fishes, having retained more
+of symmetrical structure than the other members of the family, and,
+therefore, their eyes are as often found on the right as on the left
+side. It seems to swim, not unfrequently,<span class="pagenum" id="Page_555">[555]</span> in a vertical position. Only
+one species is known, <i>Ps. erumei</i>, common in the Indian Ocean.</p>
+
+<p>
+<span class="smcap">Hippoglossus.</span>—Eyes on the right side; mouth wide, the
+length of the maxillary being one-third of that of the head.
+Teeth in the upper jaw in a double series; the anterior of the
+upper jaw and the lateral of the lower strong. The dorsal fin
+commences above the eye.
+</p>
+
+<p>The “Holibut” (<i>H. vulgaris</i>) is the largest of all Flat-fishes,
+attaining to a length of five and six feet, and a weight of several
+hundredweights. It is found along the northern coasts of Europe, on the
+coasts of Kamtschatka and California, particularly frequenting banks
+situated at some distance from the coast, and at a depth of 50 to 120
+fathoms.</p>
+
+<p>Other genera, with nearly symmetrical mouth, in which the dorsal fin
+commences above the eye, are <i>Hippoglossoides</i> (the “Rough Dab”)
+and <i>Tephritis</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhombus.</span>—Eyes on the left side. Mouth wide, the length
+of the maxillary being more than one-third of that of the head.
+Each jaw with a band of villiform teeth, without canines;
+vomerine teeth, none on the palatines. The dorsal fin commences
+on the snout. Scales none or small.</p>
+</div>
+
+<p>Seven species from the North Atlantic and Mediterranean, of which
+the most noteworthy are the “Turbot,” <i>Rh. maximus</i>, one of the
+most valued food-fishes, and growing to a length of three feet; the
+“Turbot of the Black Sea,” <i>Rh. mæoticus</i>, the body of which is
+covered with bony, conical tubercles, which are as large as the eye;
+the “Brill,” <i>Rh. lævis</i>, represented on the North American coasts
+by <i>Rh. aquosus</i>; the “Whiff,” or “Mary-sole,” or “Sail-fluke,”
+<i>Rh. megastoma</i>; “Bloch’s Top-knot,” <i>Rh. punctatus</i>
+(described by Yarrell as <i>Rh. hirtus</i>, and often confounded with
+the following species).</p>
+
+<p><span class="smcap">Phrynorhombus</span>, differing from <i>Rhombus</i> in lacking
+vomerine teeth. The scales are very small and spiny.</p>
+
+<p>The “Top-knot” (<i>Ph. unimaculatus</i>) occurs occasionally<span class="pagenum" id="Page_556">[556]</span> on the
+south coast of England, and is more common in the Mediterranean; it is
+a small species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Arnoglossus.</span>—Mouth wide, the length of the maxillary
+being more or not much less than one-third of that of the head.
+Teeth minute, in a single series in both jaws; vomerine or
+palatine teeth none. The dorsal fin commences on the snout.
+Scales of moderate size, deciduous; lateral line with a strong
+curve above the pectoral. Eyes on the left side.</p>
+</div>
+
+<p>Seven species from European and Indian Seas. The “Scald-fish” (<i>A.
+laterna</i>) is common in the Mediterranean, and extends to the south
+coast of England; it is a small species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pseudorhombus.</span>—Mouth wide, the length of the maxillary
+being more than one-third of that of the head. Teeth in both
+jaws in a single series, of unequal size; vomerine or palatine
+teeth none. The dorsal fin commences on the snout. Scales small;
+lateral line with a strong curve anteriorly. Eyes on the left
+side. Interorbital space not concave.</p>
+</div>
+
+<p>A tropical genus with a few outlying species, represented chiefly in
+the Indo-Pacific, and also in the Atlantic. Seventeen species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhomboidichthys.</span>—Mouth of moderate width or small.
+Teeth minute, in a single or double series; vomerine or palatine
+teeth none. Eyes separated by a concave more or less broad
+space. The dorsal fin commences on the snout. Scales ciliated;
+lateral line with a strong curve anteriorly. Eyes on the left
+side.</p>
+</div>
+
+<p>A tropical genus, but also represented in the Mediterranean and on the
+coast of Japan. Sixteen species, the majority of which are prettily
+coloured and ornamented with ocellated spots; in some species the adult
+males have some of the fin-rays prolonged into filaments.</p>
+
+<p>Other genera with nearly symmetrical mouth, in which the dorsal
+fin commences before the eye, on the snout, are <i>Citharus</i>,
+<i>Anticitharus</i>, <i>Brachypleura</i>, <i>Samaris</i>,
+<i>Psettichthys</i>, <i>Citharichthys</i>, <i>Hemirhombus</i>,
+<i>Paralichthys</i>, <i>Liopsetta</i>, <i>Lophonectes</i>,
+<i>Lepidopsetta</i>, and <i>Thysanopsetta</i>.</p>
+
+<p><span class="pagenum" id="Page_557">[557]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pleuronectes.</span>—Cleft of the mouth narrow, with the
+dentition much more developed on the blind side than on the
+coloured. Teeth in a single or in a double series, of moderate
+size; palatine and vomerine teeth none. The dorsal fin commences
+above the eye. Scales very small or entirely absent. Eyes
+generally on the right side.</p>
+</div>
+
+<p>This genus is characteristic of the littoral fauna of the northern
+temperate zone, a few species ranging to the Arctic circle.
+Twenty-three species are known, of which the following are the most
+noteworthy: <i>P. platessa</i>, the “Plaice,” ranging from the coast of
+France to Iceland; <i>P. glacialis</i>, from the Arctic coasts of North
+America; <i>P. americanus</i>, the transatlantic representative of the
+Plaice; <i>P. limanda</i>, the common “Dab;” <i>P. microcephalus</i>,
+the “Smear-dab;” <i>P. cynoglossus</i>, the “Craig-fluke;” <i>P.
+flesus</i>, the “Flounder.”</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhombosolea.</span>—Eyes on the right side, the lower in
+advance of the upper. Mouth narrower on the right side than on
+the left; teeth on the blind side only, villiform; palatine and
+vomerine teeth none. The dorsal fin commences on the foremost
+part of the snout. Only one ventral which is continuous with the
+anal. Scales very small, cycloid; lateral line straight.</p>
+</div>
+
+<p>This genus represents <i>Pleuronectes</i> in the Southern Hemisphere,
+but consists of three species only, which occur on the coasts of New
+Zealand, and are valued as food-fishes.</p>
+
+<p>Other genera, with narrow unsymmetrical mouth, in which the upper
+eye is not in advance of the lower, and which have pectoral fins,
+are <i>Parophrys</i>, <i>Psammodiscus</i>, <i>Ammotretis</i>,
+<i>Peltorhamphus</i>, <i>Nematops</i>, <i>Læops</i>, and
+<i>Poecilopsetta</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Solea.</span>—Eyes on the right side, the upper being more or
+less in advance of the lower. Cleft of the mouth narrow, twisted
+round to the left side. Villiform teeth on the blind side only;
+vomerine or palatine teeth none. The dorsal fin commences on the
+snout, and is not confluent with the caudal. Scales very small,
+ctenoid; lateral line straight.</p>
+</div>
+
+<p>“Soles” are numerously represented in all suitable localities<span class="pagenum" id="Page_558">[558]</span> within
+the temperate and tropical zones, with the exception of the southern
+parts of the southern temperate zone, in which they are absent. Some
+enter or live in fresh water. Nearly forty species are known. British
+are <i>S. vulgaris</i>, the common “Sole;” <i>S. aurantiaca</i>, the
+“Lemon-sole,” which is rather a southern species, and inhabits, on
+the south coast of England, deeper water than the common Sole; <i>S.
+variegata</i>, the “Banded Sole,” with very small pectoral fins;
+and <i>S. minuta</i>, the “Dwarf-Sole.”—Allied to <i>Solea</i> are
+<i>Pardachirus</i> and <i>Liachirus</i> from the Indian coasts.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Synaptura.</span>—Eyes on the right side, the upper in
+advance of the lower. Cleft of the mouth narrow, twisted round
+to the left side; minute teeth on the left side only. Vertical
+fins confluent. Scales small, ctenoid; lateral line straight.</p>
+</div>
+
+<p>Twenty species; with the exception of two from the Mediterranean
+and coast of Portugal, all belong to the fauna of the Indian
+Ocean.—Closely allied is <i>Aesopia</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gymnachirus.</span>—Mouth very small, toothless. Scales none,
+lateral line straight. Eyes on the right side. The dorsal fin
+commences on the snout; caudal free. Pectorals rudimentary or
+entirely absent.</p>
+</div>
+
+<p>Two species from the Tropical Atlantic.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cynoglossus.</span>—Eyes on the left side; pectorals none;
+vertical fins confluent. Scales ctenoid; lateral line on the
+left side double or triple; upper part of the snout produced
+backwards into a hook; mouth unsymmetrical, rather narrow. Teeth
+minute, on the right side only.</p>
+</div>
+
+<p>Abundant in the Indian seas, and especially on the flat sandy shores
+of China. About thirty-five species are known, which rarely exceed a
+length of eighteen inches. They are easily recognised by their long
+narrow shape (which has been compared to a dog’s tongue) and the
+peculiar form of their snout.</p>
+
+<p>To complete the list of Pleuronectoid genera, the following<span class="pagenum" id="Page_559">[559]</span> have
+to be mentioned: <i>Soleotalpa</i> and <i>Apionichthys</i>, Soles
+with rudimentary eyes; <i>Ammopleurops</i>, <i>Aphoristia</i>, and
+<i>Plagusia</i>, which are closely allied to <i>Cynoglossus</i>, the
+latter genus having the lips provided with tentacles.</p>
+
+
+<h4 class="smcap">Fourth Order—Physostomi.</h4>
+
+<p><i>All the fin-rays articulated, only the first of the dorsal and
+pectoral fins is sometimes ossified. Ventral fins, if present,
+abdominal, without spine. Air-bladder, if present, with a pneumatic
+duct (except in Scombresocidæ).</i></p>
+
+
+<h6 class="smcap">First Family—Siluridæ.</h6>
+
+<p><i>Skin naked or with osseous scutes, but without scales. Barbels
+always present; maxillary bone rudimentary, almost always forming a
+support to a maxillary barbel. Margin of the upper jaw formed by the
+intermaxillaries only. Suboperculum absent. Air-bladder generally
+present, communicating with the organ of hearing by means of the
+auditory ossicles. Adipose fin present or absent.</i></p>
+
+<p>A large family, represented by numerous genera, which exhibit a great
+variety of form and structure of the fins; they inhabit the fresh
+waters of all the temperate and tropical regions; a few enter the sea
+but keep near the coast. The first appearance of Siluroids is indicated
+by some fossil remains in tertiary deposits of the highlands of Padang
+in Sumatra, where <i>Pseudeutropius</i> and <i>Bagarius</i>, types well
+represented in the living Indian fauna, have been found. Also in North
+America spines referable to Cat-fishes have been found in tertiary
+formations.</p>
+
+<p>The skeleton of the typical Siluroids shows many peculiarities. The
+cranial cavity is not membranous on the sides,<span class="pagenum" id="Page_560">[560]</span> but closed as in the
+Cyprinidæ, by the orbitosphenoids and the ethmoid that unite with
+the prefrontals, carrying forward the cranial cavity to the nasal
+bone, without leaving a membranous septum between the orbits. But the
+supraoccipital is greatly developed, and in many the post-temporal is
+united by suture to the sides of the cranium. In numerous members of
+the family the skull is enlarged posteriorly, by dermal ossifications,
+to form a kind of helmet which spreads over the nape; the lateral
+angles of this production are formed by the suprascapulæ, augmented
+and fixed by suture, and the median part is the extension of the
+supraoccipital, which is generally very large, is connected anteriorly
+with the frontal, and passing backwards between the postfrontals, the
+parietals, the mastoids, and the suprascapulæ, goes past them all on
+to the nape. The mastoids interpose between the postfrontals and the
+parietals, so as to come in contact with the supraoccipital, and the
+parietals but little developed are pressed to the back part of the
+cranium, and in some instances wholly disappear.</p>
+
+<p>The suprascapula most frequently unites to the mastoid by an immovable
+suture, which includes the parietal when that bone is present, and
+extends even to the supraoccipital. It gives out besides two processes,
+one of them resting on the exoccipital and basi-occipital, or wedging
+itself between them, and the other going to the first vertebra;
+sometimes a plate from the exoccipital supports the same vertebra. This
+vertebra, though it presents a pretty continuous centrum beneath, is in
+reality composed of three or four coalescent vertebræ, as we ascertain
+by its diapophyses, by the circular elevations of the neural canal, and
+by the holes for the exit of the pairs of spinal nerves. There is great
+variety in the development of the various processes of the bones we
+have mentioned, and there is no less in the magnitude and connections
+of the first three interneurals.</p>
+
+<p>In general in the species which have a strong dorsal<span class="pagenum" id="Page_561">[561]</span> spine the second
+and third interneurals unite to form a single plate, the “buckler;” the
+great spine is articulated to the third interneural, and there is only
+the vestige of a spine on the second interneural in form of a small
+oval bone, forked below, whose function is to act as a bolt or fulcrum
+to the great spine when the fish wishes to use it as an offensive
+weapon. The great spine itself is joined by a ring to a second spine,
+which belongs to the third interneural. This articulation by ring
+exists in Lophius and a few other fishes not of this family.</p>
+
+<p>The first interneural does not carry a ray, and it varies much in
+the species whose helmet is continuous with the buckler, as in
+many of the Bagri and Pimelodi. In these cases the supraoccipital,
+extending backwards, conceals the first interneural, passing over it
+to touch with its point the buckler formed by the second and third
+interneurals. In other instances, as in Synodontis and Auchenipterus,
+the supraoccipital and second interneural, forking and expanding,
+inclose and join themselves to the first interneural, but leave a
+larger or smaller space in the middle of the nuchal armour which they
+contribute to form. When the point of the supraoccipital does not reach
+quite to the second interneural, the first interneural remains free
+from connection, and occasionally shows as a narrow plate interposed
+between the other two; in such a case the helmet is not continuous with
+the buckler.</p>
+
+<p>The neural spines of the coalescent centra, which form the
+apparently single first vertebra, concur also in sustaining the
+nuchal plate-armour and the first great dorsal spine. They carry the
+interneurals, are joined to them by suture, and one of them is often
+inclined towards the occiput to assist in sustaining the head; in fact,
+this part of the skeleton is constructed to give firm mutual support.</p>
+
+<p>The shoulder-girdle of the Siluroids is also formed to give<span class="pagenum" id="Page_562">[562]</span>
+resistance to the strong weapon with which it is frequently armed. The
+post-temporal, as we have said above, is often united by suture to the
+cranium, and it obtains support below by one or two processes that
+are fixed on the basioccipitals and on the diapophysis of the first
+vertebra.</p>
+
+<p>In most osseous fishes the clavicle completes the lower key of the
+scapular arch in joining its fellow by suture or synchondrosis without
+the intervention of the coracoid; but in the Siluroids the coracoid
+descends to take part in this joint, and sometimes even to occupy the
+half of the suture, which is not unfrequently constructed of very deep
+interlocking serratures. The solidity of this base of the pectoral
+spine is further augmented by the intimate union of the coracoid
+and scapula, which often extends to junction by suture, or even to
+coalescence; and these bones, moreover, give off two bony arches—the
+first a slender one, arising from the salient edge of the coracoid
+near the pectoral fin, and going to the interior face of the scapular
+that is applied to the interior surface of the ascending branch of the
+clavicle; the second and broader supplementary arch is often perforated
+by a large hole; it also emanates from the same salient edge of the
+radius, but proceeds in opposite direction to the inferior edge of the
+clavicle, a little before the insertion of the pectoral spine. The two
+arches give attachments to the muscles that move this spine; in the
+Synodontes and many Bagri the upper arch remains in a cartilaginous or
+ligamentous condition, while in Malapterurus it is the lower arch that
+does not ossify, but both are fully formed in the Siluri and many other
+Siluroids more closely allied to that typical genus. The postclavicle
+is also wanting in the Siluroids. The pterygoid and entopterygoid are
+reduced to a single bone, the symplectic is wholly wanting, and the
+palatine is merely a slender cylindrical bone. The sub-operculum is
+likewise constantly absent in all the Siluroids.</p>
+
+<p><span class="pagenum" id="Page_563">[563]</span></p>
+
+<p>The great number of different generic types has necessitated a further
+division of this family into eight subdivisions:</p>
+
+<p>I. <span class="smcap">Siluridæ Homalopteræ.</span>—<i>The dorsal and anal fins are
+very long, nearly equal in extent to the corresponding parts of the
+vertebral column.</i></p>
+
+
+<p class="center p1"><i>a</i>. <span class="smcap">Clariina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Clarias.</span>—Dorsal fin extending from the neck to the
+caudal, without adipose division. Cleft of the mouth transverse,
+anterior, of moderate width; barbels eight; one pair of nasal,
+one of maxillary, and two pairs of mandibulary barbels. Eyes
+small. Head depressed; its upper and lateral parts are osseous,
+or covered with only a very thin skin. A dendritic accessory
+branchial organ is attached to the convex side of the second and
+fourth branchial arches, and received in a cavity behind the
+gill-cavity proper. Ventrals six-rayed; only the pectoral has a
+pungent spine. Body eel-like.</p>
+</div>
+
+<p>Twenty species from Africa, the East Indies, and the intermediate parts
+of Asia; some attain to a length of six feet. They inhabit muddy and
+marshy waters; the physiological function of the accessory branchial
+organ is not known. Its skeleton is formed by a soft cartilaginous
+substance covered by mucous membrane, in which the vessels are
+imbedded. The vessels arise from branchial arteries, and return the
+blood into branchial veins. The vernacular name of the Nilotic species
+is “Carmoot.”</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Heterobranchus</span> differs from <i>Clarias</i> only in the
+structure of the dorsal fin, the posterior portion of which is
+adipose.</p>
+</div>
+
+<p>The geographical range of this genus is not quite co-extensive with
+that of <i>Clarias</i>, inasmuch as it is limited to Africa and the
+East-Indian Archipelago. Six species.</p>
+
+
+<p class="center p1"><i>b</i>. <span class="smcap">Plotosina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Plotosus.</span>—A short dorsal fin in front, with a pungent
+spine; a second long dorsal coalesces with the caudal and
+anal. Vomerine teeth molar-like. Barbels eight or ten; one
+immediately<span class="pagenum" id="Page_564">[564]</span> before the posterior nostril, which is remote from
+the anterior, the latter being quite in front of the snout.
+Cleft of the mouth transverse. Eyes small. The gill-membranes
+are not confluent with the skin of the isthmus. Ventral fins
+many-rayed. Head depressed; body elongate.</p>
+</div>
+
+  <div class="figcenter" id="fig258" style="max-width: 324px">
+     <img
+    class="p1"   
+    src="images/fig258.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 258.—Mouth of Cnidoglanis megastoma, Australia.</p>
+  </div>
+
+<p>Three species are known from brackish waters of the Indian Ocean freely
+entering the sea. <i>Plotosus anguillaris</i> is distinguished by two
+white longitudinal bands, and is one of the most generally distributed
+and common Indian fishes.—<i>Copidoglanis</i> and <i>Cnidoglanis</i>
+are two very closely allied forms, chiefly from rivers and brackish
+waters of Australia. None of these Siluroids attain to a considerable
+size. <i>Chaca</i>, from the East Indies, belongs likewise to this
+sub-family.</p>
+
+  <div class="figcenter" id="fig259">
+     <img
+    class="p1"   
+    src="images/fig259.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 259.—Cnidoglanis microcephalus.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_565">[565]</span></p>
+
+<p>II. <span class="smcap">Siluridæ Heteropteræ.</span>—<i>The rayed dorsal fin is very
+little developed, and, if it is present, it belongs to the abdominal
+portion of the vertebral column; the adipose fin is exceedingly small
+or absent. The extent of the anal is not much inferior to that of
+the caudal vertebral column. The gill-membranes overlap the isthmus,
+remaining more or less separate</i>: <span class="smcap">Silurina</span>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Saccobranchus.</span>—Adipose fin none; dorsal very short,
+without pungent spine, placed above the ventrals. Cleft of the
+mouth transverse, anterior, of moderate width; barbels eight.
+Eyes rather small. The upper and lateral parts of the head
+osseous or covered with a very thin skin. Gill-cavity with an
+accessory posterior sac, extending backwards between the muscles
+along each side of the abdominal and caudal portions of the
+vertebral column. Ventrals six-rayed.</p>
+</div>
+
+<p>Small fishes from East Indian rivers; four species are known. The
+lung-like extension of the branchial cavity receives water, and is
+surrounded by contractile transverse muscular fibres by which the water
+is expelled at intervals. The vessels of the sac take their origin in
+the last branchial artery, and pass into the aorta.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Silurus.</span>—No adipose fin; one very short dorsal,
+without pungent spine. Barbels four or six, one to each
+maxillary, and one or two to each mandible. Nostrils remote from
+each other. Head and body covered with soft skin. The eye is
+situated above the level of the angle of the mouth. The dorsal
+fin is anterior to the ventrals which are composed of more than
+eight rays. Caudal rounded.</p>
+</div>
+
+<p>This genus, of which five species are known, inhabits the temperate
+parts of Europe and Asia. The species which has given the name to the
+whole family, is the “Wels” of the Germans, <i>Silurus glanis</i>. It
+is found in the fresh waters east of the Rhine, and is, besides the
+Sturgeons, the largest of European Freshwater-fishes, and the only
+species of this family which occurs in Europe. Barbels six. It attains
+to<span class="pagenum" id="Page_566">[566]</span> a weight of 300 or 400 lbs., and the flesh, especially of smaller
+specimens, is firm, flaky, and well flavoured. Aristotle described it
+under the name of <i>Glanis</i>. Its former occurrence in Scotland has
+justly been denied. In China it is represented by a similar species,
+<i>S. asotus</i>, which, however, has four barbels only.</p>
+
+  <div class="figcenter" id="fig260">
+     <img
+    class="p1"   
+    src="images/fig260.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 260.—The “Wels,” Siluris glanis.</p>
+  </div>
+
+<p>This sub-family is well represented by various other genera in
+the fresh waters of the African as well as Indian region. African
+genera are <i>Schilbe</i> and <i>Eutropius</i>; East Indian:
+<i>Silurichthys</i>, <i>Wallago</i>, <i>Belodontichthys</i>,
+<i>Eutropiichthys</i>, <i>Cryptopterus</i>, <i>Callichrous</i>,
+<i>Hemisilurus</i>, <i>Siluranodon</i>, <i>Ailia</i>,
+<i>Schilbichthys</i>, <i>Lais</i>, <i>Pseudeutropius</i>,
+<i>Pangasius</i>, <i>Helicophagus</i>, and <i>Silondia</i>.</p>
+
+<p>III. <span class="smcap">Siluridæ Anomalopteræ.</span>—<i>Dorsal and adipose fins very
+short, the former belonging to the caudal vertebral column; anal
+very long. Ventrals in front of the dorsal. Gill-membranes entirely
+separate, overlapping the isthmus</i>: (<span class="smcap">Hypophthalmina</span>.)</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hypophthalmus.</span>—Dorsal fin with seven rays, the first
+of which is slightly spinous. The lower jaw is rather the
+longer. Barbels six, those of the mandible long. No teeth;
+intermaxillaries very feeble. Head covered with skin. Eye of
+moderate size, situated behind and below the angle of the mouth.
+Ventrals small, six-rayed.</p>
+</div>
+
+<p><span class="pagenum" id="Page_567">[567]</span></p>
+
+<p>Four species from tropical America. The second genus of this sub-family
+is <i>Helogenes</i> from the Essequibo.</p>
+
+
+<p>IV. <span class="smcap">Siluridæ Proteropteræ.</span>—<i>The rayed dorsal fin is always
+present, short, with not more than twelve short rays, and belongs to
+the abdominal portion of the vertebral column, being placed in advance
+of the ventrals. The adipose fin is always present and well developed,
+although frequently short. The extent of the anal is much inferior
+to that of the caudal vertebral column. The gill-membranes are not
+confluent with the skin of the isthmus, their posterior margin always
+remaining free even if they are united with each other. Whenever the
+nasal barbel is present it belongs to the posterior nostril.</i></p>
+
+
+<p class="center p1"><i>a.</i> <span class="smcap">Bagrina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bagrus.</span>—Adipose fin long; a short dorsal with a
+pungent spine and nine or ten soft rays; anal fin short, with
+less than twenty rays. Barbels eight. The anterior and posterior
+nostrils are remote from each other, the posterior being
+provided with a barbel. Teeth on the palate in a continuous
+band. Eyes with a free orbital margin. Caudal forked; ventrals
+six-rayed.</p>
+</div>
+
+<p>This genus consists of two species only, common in the Nile, viz.
+the “Bayad,” <i>B. bayad</i>, and <i>B. docmac</i>. Both grow to
+a large size, exceeding a length of five feet, and are eaten.
+<i>Chrysichthys</i> and <i>Clarotes</i> are two other Siluroid
+genera from African rivers, closely allied to Bagrus. Similar
+Siluroids are common in the East Indies, and have been referred
+to the following genera: <i>Macrones</i>, <i>Pseudobagrus</i>,
+<i>Liocassis</i>, <i>Bagroides</i>, <i>Bagrichthys</i>, <i>Rita</i>,
+<i>Acrochordonichthys</i>, <i>Akysis</i>.</p>
+
+
+<p class="center p1"><i>b.</i> <span class="smcap">Amiurina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Amiurus.</span>—Adipose fin of moderate length; a short
+dorsal with a pungent spine and six soft rays; anal fin of
+moderate length. Barbels eight. The anterior and posterior
+nostrils are remote from each other, the posterior being
+provided with a barbel.<span class="pagenum" id="Page_568">[568]</span> Palate edentulous. Head covered with
+skin above. Ventrals eight-rayed.</p>
+</div>
+
+<p>The “Cat-fishes” of North America, of which about a dozen different
+species are known. One species occurs in China. Allied, but smaller
+forms are <i>Hopladelus</i> and <i>Noturus</i>, likewise from North
+America.</p>
+
+
+<p class="center p1"><i>c</i>. <span class="smcap">Pimelodina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Platystoma.</span>—Adipose fin of moderate length; a short
+dorsal fin with a pungent spine and six or seven soft rays; anal
+fin rather short. Snout very long, spatulate, with the upper
+jaw more or less projecting; the upper surface of the head not
+covered by the skin. Barbels six; the anterior and posterior
+nostrils remote from each other, none with a barbel. Palate
+toothed. Caudal forked; ventrals six-rayed, inserted behind the
+dorsal.</p>
+</div>
+
+<p>Twelve species from South America, some attaining a length of
+six feet, the majority being ornamented with deep-black spots or
+bands. Allied genera from South America, likewise distinguished by
+a long spatulate snout, are <i>Sorubim</i>, <i>Hemisorubim</i>,
+and <i>Platystomatichthys</i>, whilst <i>Phractocephalus</i>,
+<i>Piramutana</i>, <i>Platynematichthys</i>, <i>Piratinga</i>,
+<i>Bagropsis</i>, and <i>Sciades</i>, have a snout of ordinary length.
+The barbels of some are of extraordinary length, and not rarely dilated
+and band-like.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pimelodus.</span>—Adipose fin well developed; dorsal fin
+short, with a more or less pungent spine and six rays; anal fin
+short. Barbels six, cylindrical or slightly compressed, none
+of them belonging to either of the nostrils, which are remote
+from each other. Palate edentulous. Ventrals six-rayed, inserted
+behind the dorsal.</p>
+</div>
+
+<p>Of all South American genera this is represented by the greatest
+number of species, more than forty being well characterised; they
+differ chiefly with regard to the length of the adipose fin and
+barbels, and the strength of the dorsal<span class="pagenum" id="Page_569">[569]</span> spine. Singularly, two
+species (<i>P. platychir</i> and <i>P. balayi</i>), are found
+in West Africa. The majority are of but moderate size and plain
+coloration.—Allied South American genera (also without teeth on the
+palate), are <i>Pirinampus</i>, <i>Conorhynchus</i>, <i>Notoglanis</i>,
+<i>Callophysus</i>, <i>Lophiosilurus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Auchenoglanis.</span>—Adipose fin rather long, dorsal short,
+with a pungent spine and seven rays; anal short. Snout produced,
+pointed, with narrow mouth. Barbels six, none of which belongs
+to either of the nostrils, which are remote from each other. The
+teeth of each jaw form a pair of small elliptic patches which
+are longer than broad; palate edentulous. Eyes of moderate size.
+Ventrals six-rayed.</p>
+</div>
+
+<p>One species, <i>Au. biscutatus</i>, from the Nile, Senegal, and other
+West African rivers.</p>
+
+
+<p class="center p1"><i>d.</i> <span class="smcap">Ariina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Arius.</span>—Adipose fin of moderate length or short; a
+short dorsal fin with a pungent spine and seven soft rays; anal
+fin rather short. Head osseous above; barbels six, four at
+the mandible, none at either of the nostrils which are close
+together. Eyes with a free orbital margin. Caudal fin forked;
+ventrals six-rayed, behind the dorsal.</p>
+</div>
+
+<p>Of all Siluroid genera this has the greatest number of species
+(about seventy), and the widest distribution, being represented in
+almost all tropical countries which are drained by large rivers;
+some of the species prefer brackish to fresh water, and a few enter
+the sea, but keep near to the coast. Some of the species are of
+small size, whilst others exceed a length of five feet. The extent
+of the armature of the neck and the dentition vary much in the
+different species, and affords two of the principal characters by
+which the species are separated.—The following genera are allied to
+<i>Arius</i>, <i>Galeichthys</i> from South Africa; <i>Genidens</i>
+and <i>Paradiplomystax</i> from Brazil; <i>Diplomystax</i> from
+Chile; <i>Aelurichthys</i> from Central and South America;
+<i>Hemipimelodus</i>, <i>Ketengus</i>, <i>Osteo</i><i>geniosus</i>,<span class="pagenum" id="Page_570">[570]</span>
+and <i>Batrachocephalus</i> from the East Indies; and
+<i>Atopochilus</i> from West Africa.</p>
+
+  <div class="figcenter" id="fig261" style="max-width: 240px">
+     <img
+    class="p1"   
+    src="images/fig261.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 261.—Arius australis, from Queensland.</p>
+  </div>
+
+<p><i>e.</i> <span class="smcap">Bagariina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bagarius.</span>—Adipose fin rather short; a short dorsal
+with one spine and six rays; anal fin of moderate length.
+Barbels eight, of which one pair stands between the anterior and
+posterior nostrils which are close together. Head naked above.
+Caudal fin deeply forked; ventrals rays six. Thorax without
+longitudinal plaits of the skin.</p>
+</div>
+
+<p><span class="pagenum" id="Page_571">[571]</span></p>
+
+<p>A large Siluroid (<i>B. bagarius</i>) from rivers of India and Java;
+exceeding a length of six feet.</p>
+
+  <div class="figcenter" id="fig262" style="max-width: 255px">
+     <img
+    class="p1"   
+    src="images/fig262.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 262.—Euglyptosternum coum, thoracic adhesive
+apparatus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Euglyptosternum.</span>—Adipose fin of moderate length; a
+short dorsal with a pungent spine and six rays; anal fin short.
+Barbels eight, of which one pair is placed between the anterior
+and posterior nostrils which are close together. Teeth on the
+palate villiform, in two separate patches. Eyes small, below the
+skin. Caudal forked; ventral rays six. Pectorals horizontal,
+with a thoracic adhesive apparatus between, which is formed by
+longitudinal plaits of the skin.</p>
+</div>
+
+<p>This fish (<i>Eu. coum</i>) inhabits the river Coic in Syria, and is
+about twelve inches long. The plaited structure on the thorax probably
+increases the capability of the fish of maintaining its position
+in the rapid current of the stream, a function which appears to be
+chiefly performed by the horizontally expanded pectoral fins. A similar
+structure is found in<span class="pagenum" id="Page_572">[572]</span> <i>Glyptosternum</i>, a genus represented by
+eight species in mountain streams of the East Indies, and differing
+from the Syrian species in lacking the teeth on the palate.</p>
+
+<p>V. <span class="smcap">Siluridæ Stenobranchiæ.</span>—<i>The rayed dorsal fin is short,
+if present, belonging to the abdominal portion of the vertebral column,
+the ventrals being inserted behind it (except in Rhinoglanis). The
+gill-membranes are confluent with the skin of the isthmus.</i></p>
+
+
+<p class="center p1"><i>a</i>. <span class="smcap">Doradina.</span></p>
+
+<p>Some of the genera have no bony shields along the lateral line,
+and a small adipose fin or none whatever; all of these are South
+American—<i>Ageniosus</i>, <i>Tetranematichthys</i>, <i>Euanemus</i>,
+<i>Auchenipterus</i>, <i>Glanidium</i>, <i>Centromochlus</i>,
+<i>Trachelyopterus</i>, <i>Cetopsis</i>, and <i>Astrophysus</i>.</p>
+
+<p>Others have a series of bony scutes along the middle of the side;
+they form the genus <i>Doras</i> with two closely allied forms,
+<i>Oxydoras</i> and <i>Rhinodoras</i>. Some twenty-five species are
+known, all from rivers of tropical America, flowing into the Atlantic.
+These fishes have excited attention by their habit of travelling,
+during the dry season, from a piece of water about to dry up, in quest
+of a pond of greater capacity. These journeys are occasionally of such
+a length that the fish spends whole nights on the way, and the bands of
+scaly travellers are sometimes so large that the Indians who happen to
+meet them, fill many baskets of the prey thus placed in their hands.
+The Indians supposed that the fish carry a supply of water with them,
+but they have no special organs, and can only do so by closing the
+gill-openings, or by retaining a little water between the plates of
+their bodies, as Hancock supposes. The same naturalist adds that they
+make regular nests, in which they cover up their eggs with care and
+defend them, male and female uniting in this parental duty until the
+eggs are hatched. The nest is constructed at<span class="pagenum" id="Page_573">[573]</span> the beginning of the
+rainy season, of leaves, and is sometimes placed in a hole scooped out
+in the beach.</p>
+
+<p>Finally, in the last genus, the lateral scutes are likewise absent,
+viz. in</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Synodontis.</span>—The adipose fin is of moderate length or
+rather long; the dorsal fin has a very strong spine and seven
+soft rays. The teeth in the lower jaw are movable, long, very
+thin at the base, and with a slightly-dilated brown apex. Mouth
+small. Barbels six, more or less fringed with a membrane or with
+filaments. Neck with broad dermal bones.</p>
+</div>
+
+<p>Synodontis is characteristic of the fauna of tropical Africa, where it
+is represented by fifteen species. Several occur in the Nile, and are
+known by the vernacular name “Schal.” Some attain a length of two feet.
+The species figured is from West Africa, and characterised by its long
+upper jaw.</p>
+
+  <div class="figcenter" id="fig263">
+     <img
+    class="p1"   
+    src="images/fig263.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 263.—Synodontis xiphias.</p>
+  </div>
+
+<p class="center p1"><i>b</i>. <span class="smcap">Rhinoglanina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhinoglanis.</span>—Two dorsal fins, both composed of rays,
+the first with a strong spine; anal rather short. Barbels six;
+anterior and posterior nostrils close together, the posterior
+very large, open. Neck with broad dermal bones. Ventrals with
+seven rays, inserted below the posterior rays of the first
+dorsal fin.</p>
+
+<p>This Siluroid is known from a single example only one and a
+half inches long, obtained at Gondokoro on the Upper Nile.
+<i>Callomystax</i> represents this type in the Ganges and Indus.</p>
+</div>
+
+<p><span class="pagenum" id="Page_574">[574]</span></p>
+
+
+<p class="center p1"><i>c</i>. <span class="smcap">Malapterurina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Malapterurus.</span>—One dorsal fin only, which is adipose
+and situated before the caudal; anal of moderate length or
+short; caudal rounded; ventrals six-rayed, inserted somewhat
+behind the middle of the body; pectorals without pungent spine.
+Barbels six: one to each maxillary and two on each side of the
+mandible. The anterior and posterior nostrils are remote from
+each other. No teeth on the palate. The entire head and body
+covered with soft skin. Eyes small. Gill-opening very narrow,
+reduced to a slit before the pectoral.</p>
+</div>
+
+<p>The “Electric Cat- or Sheath-fishes” are not uncommon in the fresh
+waters of tropical Africa; three species have been described, of which
+<i>M. electricus</i> occurs in the Nile; they grow to a length of about
+four feet. Although the first dorsal fin is absent, its position (if it
+had been developed) is indicated by a rudimentary interneural spine,
+which rests in the cleft of the neural process of the first vertebra.
+The electric organ extends over the whole body, but is thickest on the
+abdomen; it lies between two aponeurotic membranes, below the skin, and
+consists of rhomboidal cells which contain a rather firm gelatinous
+substance. The electric nerve takes its origin from the spinal chord,
+does not enter into connection with ganglia, and consists of a single
+enormously-strong primitive fibre, which distributes its branches in
+the electric organ.</p>
+
+  <div class="figcenter" id="fig264">
+     <img
+    class="p1"   
+    src="images/fig264.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 264.—Malapterurus electricus.</p>
+  </div>
+
+<p>VI. <span class="smcap">Siluridæ Proteropodes.</span>—<i>The rayed dorsal fin is always
+present and rather short; the ventrals are inserted below<span class="pagenum" id="Page_575">[575]</span> (very rarely
+in front of) the dorsal. The gill-membranes are confluent with the
+skin of the isthmus, the gill-opening being reduced to a short slit.
+Pectorals and ventrals horizontal. Vent before, or not much behind, the
+middle of the length of the body.</i></p>
+
+
+<p class="center p1"><i>a</i>. <span class="smcap">Hypostomatina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Stygogenes.</span>—Adipose fin short; dorsal and anal
+short; the outer fin-rays somewhat thickened and rough; palate
+toothless; cleft of the mouth of moderate width, with a
+maxillary barbel on each side; a short broad flap on each side
+between the nostrils, which are close together. Lower lip very
+broad, pendent. Eyes small, covered with transparent skin. Head
+covered with soft skin. Ventrals six-rayed.</p>
+</div>
+
+<p>These small Siluroids, which are called “Preñadillas” by the
+natives, together with the allied <i>Arges</i>, <i>Brontes</i>, and
+<i>Astroplebus</i>, have received some notoriety through Humboldt’s
+accounts, who adopted the popular belief that they live in subterranean
+waters within the bowels of the active volcanoes of the Andes, and
+are ejected with streams of mud and water during eruptions. Humboldt
+himself considers it very singular that they are not cooked and
+destroyed whilst they are vomited forth from craters or other openings.
+The explanation of their appearance during volcanic eruptions is, that
+they abound in the numerous lakes and torrents of the Andes, that they
+are killed by the sulphuretted gases escaping during an eruption, and
+swept down by the torrents of water issuing from the volcano.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Callichthys.</span>—Adipose fin short, supported anteriorly
+by a short movable spine; dorsal with a feeble spine and seven
+or eight rays; anal short. Teeth minute or entirely absent;
+cleft of the mouth rather narrow, with a pair of maxillary
+barbels on each side, which are united at the base. Eyes small.
+Head covered with osseous plates; body wholly protected by
+two series of large imbricate shields on each side. Ventrals
+six-rayed.</p>
+</div>
+
+<p><span class="pagenum" id="Page_576">[576]</span></p>
+
+<p>Twelve species of this genus are known; they are small, and similarly
+distributed as <i>Doras</i>, with which they have much in common as
+regards their mode of life. They likewise are able to travel over land,
+and construct nests for their ova.</p>
+
+  <div class="figcenter" id="fig265" style="max-width: 577px">
+     <img
+    class="p1"   
+    src="images/fig265.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 265.—Callichthys armatus, from the Upper Amazon.
+Natural size.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chætostomus.</span>—A short adipose fin, supported anteriorly
+by a short, compressed, curved spine; dorsal fin of moderate
+length, with from eight to ten rays, the first of which is
+simple; anal fin short; ventral six-rayed; pectoral with a
+strong spine. Head and body completely cuirassed, the lower
+parts being sometimes naked; body rather short, with four or
+five longitudinal series of large imbricate scutes on each side;
+tail not depressed. Snout produced, obtuse in front; mouth
+inferior, transverse, with a single series of generally very
+fine bent teeth in both jaws. Interoperculum very movable and
+armed with erectile spines.</p>
+</div>
+
+<p>This genus, with the allied <i>Plecostomus</i>, <i>Liposarcus</i>,
+<i>Pterygoplichthys</i>, <i>Rhinelepis</i>, <i>Acanthicus</i>, and
+<i>Xenomystus</i>, is well represented in the fresh waters of South
+America, whence about sixty species are known. The majority do not
+exceed a length of twelve inches, but some attain to more than double
+that size. In some of the species the male is provided<span class="pagenum" id="Page_577">[577]</span> with long
+bristles round the margin of the snout and interoperculum.</p>
+
+  <div class="figcenter" id="fig266" style="max-width: 264px">
+     <img
+    class="p1"   
+    src="images/fig266.jpg"
+     alt="">
+     <p class="p0 smaller">Fig. 266.—Upper and Lower side of the head of
+<i>Chætostomus heteracanthus</i>, Upper Amazons.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_578">[578]</span></p>
+
+<div class="blockquot">
+
+<p><i>Hypoptopoma.</i>—Differing from <i>Chætostomus</i> in the
+peculiar formation of the head, which is depressed, spatulate,
+the eyes being on the lateral edge of the head. The movable
+gill-covers are reduced to two bones, neither of which is armed,
+viz.—the operculum small and placed as in <i>Chætostomus</i>,
+and a second, larger one, separated from the eye by the narrow
+sub-orbital ring, and placed at the lower side of the head.</p>
+</div>
+
+  <div class="figcenter" id="fig267" style="max-width: 568px">
+     <img
+    class="p1"   
+    src="images/fig267.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 267.—<i>Hypoptopoma thoracatum</i>, Upper Amazons.
+Natural size.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Loricaria.</span>—One short dorsal fin; anal short; the outer
+ray of each fin thickened, but flexible. Head depressed, with
+the snout more or less produced and spatulate. Mouth situated
+at the lower side of the snout, remote from its extremity,
+transverse, surrounded by broad labial folds which are sometimes
+fringed; a short barbel at each corner of the mouth. Teeth
+in the jaws small, bent, with a dilated, notched apex, in a
+single<span class="pagenum" id="Page_579">[579]</span> series, sometimes absent. Head and body cuirassed; tail
+depressed, long; eye rather small or of moderate size.</p>
+</div>
+
+  <div class="figcenter" id="fig268" style="max-width: 521px">
+     <img
+    class="p1"   
+    src="images/fig268.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 268.—<i>Loricaria lanceolate</i>, Upper Amazons.
+Natural size.</p>
+  </div>
+
+<p>Small fishes from rivers of tropical America; about twenty-six species
+are known. The male of some species has a bearded or bristly snout.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Acestra</span> differs from <i>Loricaria</i> in having the
+snout much prolonged.</p>
+</div>
+
+<p><span class="pagenum" id="Page_580">[580]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sisor.</span>—Head depressed, spatulate; trunk depressed;
+tail long and thin. One short dorsal fin; anal short; ventrals
+seven-rayed. Head partially osseous, rough; a series of bony
+plates along the median line of the back; lateral line rough.
+Eyes very small. Mouth inferior, small, transverse, with
+barbels; teeth none.</p>
+</div>
+
+<p>A single species, <i>S. rhabdophorus</i>, from rivers of northern
+Bengal. Allied to this genus is <i>Erethistes</i> from Assam.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Pseudecheneis.</span>—Adipose fin of moderate length; a
+short dorsal with one spine and six rays; anal fin rather
+short. Barbels eight. Mouth small, inferior. Head depressed,
+covered with soft skin above; eyes small, superior. Caudal fin
+forked; pectorals horizontal, with a thoracic adhesive apparatus
+between, formed by transverse plaits of the skin. Ventrals
+six-rayed.</p>
+</div>
+
+<p>A very small species, inhabiting the mountain-streams of Khassya; by
+means of the adhesive apparatus it is enabled to hold on to stones,
+thus preventing the current from sweeping it away. <i>Exostoma</i> is
+a similar small Siluroid from Indian mountain-streams, but without the
+thoracic apparatus; probably its mouth performs the same function.</p>
+
+
+<p class="center p1"><i>b</i>. <span class="smcap">Aspredinina.</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aspredo.</span>—Adipose fin none; dorsal short, without
+pungent spine; anal very long, but not united with the caudal.
+Head broad, much depressed; tail very long and slender.
+Barbels not less than six, one of which is attached to each
+intermaxillary; none at the nostrils. Eyes very small. Head
+covered with soft skin; the anterior and posterior nostrils are
+remote from each other. Ventrals six-rayed.</p>
+</div>
+
+<p>Six species are known from Guyana; the largest grows to a length of
+about eighteen inches. The remarkable mode of taking care of their
+ova has been noticed above (p. 161, Fig. <a href="#fig72">72</a>). <i>Bunocephalus</i>,
+<i>Bunocephalichthys</i>, and <i>Harttia</i>, from tropical America,
+are other genera of this sub-family which remain to be mentioned.</p>
+
+<p><span class="pagenum" id="Page_581">[581]</span></p>
+
+<p>VII. <span class="smcap">Siluridæ Opisthopteræ.</span>—<i>The rayed dorsal fin is always
+present, short, and placed above or behind the middle of the length of
+the body, above or behind the ventrals which, however, are sometimes
+absent; anal short. Nostrils remote from each other; if a nasal barbel
+is present, it belongs to the anterior nostril. Lower lip not reverted.
+The gill-membranes are not confluent with the skin of the isthmus</i>:
+<span class="smcap">Nematogenyina</span> and <span class="smcap">Trichomycterina</span>.</p>
+
+<p>The genera <i>Heptapterus</i>, <i>Nematogenys</i>,
+<i>Trichomycterus</i>, <i>Eremophilus</i>, and <i>Pariodon</i>, belong
+to this sub-family. They are small South American Siluroids, the
+majority of which inhabit waters at high altitudes, up to 14,000 feet
+above the level of the sea. In the Andes they replace the Loaches of
+the Northern Hemisphere, which they resemble in appearance and habits,
+and even in coloration, offering a striking example of the fact that
+similar forms of animals are produced under similar external physical
+conditions.</p>
+
+<p>VIII. <span class="smcap">Siluridæ Branchicolæ.</span>—<i>The rayed dorsal fin is
+present, short, and placed behind the ventrals; anal short. Vent far
+behind the middle of the length of the body. Gill-membranes confluent
+with the skin of the isthmus.</i></p>
+
+<p><i>Stegophilus</i> and <i>Vandellia</i>, two genera from South America,
+comprising the smallest and least developed Siluroids. Their body is
+narrow, cylindrical, and elongate; a small barbel at each maxillary;
+the operculum and interoperculum are armed with short stiff spines. The
+natives of Brazil accuse these fishes of entering and ascending the
+urethra of persons while bathing, causing inflammation and sometimes
+death. This requires confirmation, but there is no doubt that they live
+parasitically in the gill-cavity of larger fishes (<i>Platystoma</i>),
+but probably they enter these cavities only for places of safety,
+without drawing any nourishment from their host.</p>
+
+<p><span class="pagenum" id="Page_582">[582]</span></p>
+
+
+<h6 class="smcap">Second Family—Scopelidæ.</h6>
+
+<p><i>Body naked or scaly. Margin of the upper jaw formed by the
+intermaxillary only; opercular apparatus sometimes incompletely
+developed. Barbels none. Gill-opening very wide; pseudobranchiæ well
+developed. Air-bladder none. Adipose fin present. The eggs are enclosed
+in the sacs of the ovary, and excluded by oviducts. Pyloric appendages
+few in number or absent. Intestinal tract very short.</i></p>
+
+<p>Exclusively marine, the majority being either pelagic or deep-sea
+forms. Of fossil remains the following have been referred to this
+family:—<i>Osmeroides</i>, from Mount Lebanon, which others believe
+to be a marine salmonoid; <i>Hemisaurida</i>, from Comen, allied to
+<i>Saurus</i>; <i>Parascopelus</i> and <i>Anapterus</i>, from the
+miocene of Licata, the latter genus allied to <i>Paralepis</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Saurus</span> (inclus. <i>Saurida</i>).—Body sub-cylindrical,
+rather elongate, covered with scales of moderate size; head
+oblong; cleft of the mouth very wide; intermaxillary very long,
+styliform, tapering; maxillary thin, long, closely adherent
+to the intermaxillary. Teeth card-like, some being elongate,
+slender; all can be laid downwards and inwards. Teeth on the
+tongue, and palatine bones. Eye of moderate size. Pectorals
+short; ventrals eight- or nine-rayed, inserted in advance of the
+dorsal, not far behind the pectorals. Dorsal fin nearly in the
+middle of the length of the body, with thirteen or less rays;
+adipose fin small; anal short or of moderate length; caudal
+forked.</p>
+</div>
+
+<p>Fifteen species of small size, from the shores of the tropical and
+sub-tropical zones. The species figured on p. 42, Fig. <a href="#fig5">5</a>, occurs on the
+north-west coast of Australia and in Japan.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bathysaurus.</span>—Shape of the body similar to that of
+<i>Saurus</i>, sub-cylindrical, elongate, covered with small
+scales. Head depressed, with the snout produced, flat above.
+Cleft of the mouth<span class="pagenum" id="Page_583">[583]</span> very wide, with the lower jaw projecting;
+intermaxillary very long, styliform, tapering, not movable.
+Teeth in the jaws, in broad bands, not covered by lips, curved,
+unequal in size and barbed at the end. A series of similar teeth
+runs along the whole length of each side of the palate. Eye of
+moderate size, lateral. Pectoral of moderate length. Ventral
+eight-rayed, inserted immediately behind the pectoral. Dorsal
+fin in the middle of the length of the body, with about eighteen
+rays. Adipose fin absent or present. Anal of moderate length.
+Caudal emarginate.</p>
+</div>
+
+<p>Deep-sea fishes, obtained in the Pacific at depths varying from 1100 to
+2400 fathoms. The largest example is twenty inches long. Two species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bathypterois.</span>—Shape of the body like that of an
+<i>Aulopus</i>. Head of moderate size, depressed in front, with
+the snout projecting, the large mandible very prominent beyond
+the upper jaw. Cleft of the mouth wide; maxillary developed,
+very movable, much dilated behind. Teeth in narrow villiform
+bands in the jaws. On each side of the broad vomer a small
+patch of similar teeth; none on the palatines or on the tongue.
+Eye very small. Scales cycloid, adherent, of moderate size.
+Rays of the pectoral fin much elongated, some of the upper
+being separate from the rest, and forming a distinct division.
+Ventrals abdominal, with the outer rays prolonged, eight-rayed.
+Dorsal fin inserted in the middle of the body, above or
+immediately behind the root of the ventral, of moderate length.
+Adipose fin present or absent. Anal short. Caudal forked.</p>
+</div>
+
+<p>This very singular form is one of the discoveries of the “Challenger;”
+it is widely distributed over the seas of the Southern Hemisphere, in
+depths varying from 520 to 2600 fathoms. The elongate pectoral rays
+are most probably organs of touch. Four species were discovered, the
+largest specimen being thirteen inches long.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Harpodon.</span>—Body elongate, covered with very thin,
+diaphanous, deciduous scales. Head thick, with very short snout;
+its bones are very soft, and the superficial ones are modified
+into wide muciferous cavities; the lateral canal of the body
+is also<span class="pagenum" id="Page_584">[584]</span> very wide, and a pair of pores corresponds to each
+scale of the lateral line, one being above, the other below
+the scale. Cleft of the mouth very wide; intermaxillary very
+long, styliform, tapering; maxillary absent. Teeth card-like,
+recurved, unequal in size; the largest are in the lower jaw,
+and provided with a single barb at the posterior margin of the
+point. Eye small. Ventral fins long, nine-rayed, inserted below
+the anterior dorsal rays; dorsal fin in the middle of the length
+of the body; adipose fin small; anal of moderate length; caudal
+fin three-lobed, the lateral line being continued along the
+central lobe. Centre of the vertebræ open in the middle.</p>
+</div>
+
+<p>Two species only are known of this singular genus; both are evidently
+inhabitants of considerable depths, and periodically come nearer to the
+surface. One (<i>H. nehereus</i>) is well known in the East Indies,
+being of excellent flavour. When newly taken its body is brilliantly
+phosphorescent. When salted and dry it is known under the names
+of “Bombay-ducks” or “Bummaloh,” and exported in large quantities
+from Bombay and the coast of Malabar. The second species (<i>H.
+microchir</i>) exceeds the other in length, and has been found in the
+sea off Japan.</p>
+
+  <div class="figcenter" id="fig269">
+     <img
+    class="p1"   
+    src="images/fig269.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 269.—Scopelus boops.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scopelus.</span>—Body oblong, more or less compressed,
+covered with large scales. Series of phosphorescent spots run
+along the lower side of the body, and a similar glandular
+substance sometimes occupies the front of the snout and the
+back of the tail. Cleft of the mouth very wide. Intermaxillary
+very long, styliform, tapering; maxillary well developed. Teeth
+villiform. Eye large. Ventrals eight-rayed, inserted immediately
+in front of or<span class="pagenum" id="Page_585">[585]</span> below the anterior dorsal rays. Dorsal fin
+nearly in the middle of the length of the body; adipose fin
+small; anal generally long; caudal forked. Branchiostegals from
+eight to ten.</p>
+</div>
+
+<p>The fishes of this genus are small, of truly pelagic habits, and
+distributed over all the temperate and tropical seas; they are so
+numerous that the surface-net, when used during a night of moderate
+weather, scarcely ever fails to enclose some specimens. They come to
+the surface at night only; during the day and in very rough weather
+they descend to depths where they are safe from sunlight or the
+agitation of the water. Some species never rise to the surface; indeed,
+Scopeli have been brought up in the dredge from almost any depth to
+2500 fathoms. Thirty species are known. <i>Gymnoscopelus</i> differs
+from <i>Scopelus</i> in lacking scales.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ipnops.</span>—Body elongate, sub-cylindrical, covered with
+large, thin, deciduous scales, and without phosphorescent
+organs. Head depressed, with broad, long, spatulate snout, the
+whole upper surface of which is occupied by a most peculiar
+organ of vision (or luminosity), longitudinally divided in two
+symmetrical halves. Bones of the head well ossified. Mouth wide,
+with the lower jaw projecting; maxillary dilated behind. Both
+jaws with narrow bands of villiform teeth; palate toothless.
+Pectoral and ventral fins well developed, and, owing to the
+shortness of the trunk, close together. Dorsal fin at a short
+distance behind the vent; adipose fin none; anal fin moderately
+long; caudal subtruncated. Pseudobranchiæ none.</p>
+</div>
+
+<p>This singular genus, one of the “Challenger” discoveries, is known
+from four examples, obtained at depths varying between 1600 and 2150
+fathoms, off the coast of Brazil, near Tristan d’Acunha and north of
+Celebes. All belong to one species, <i>I. murrayi</i>. The eye seems to
+have lost its function of vision and assumed that of producing light.
+The specimens are from 4 to 5½ inches long.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Paralepis.</span>—Head and body elongate, compressed, covered
+with deciduous scales. Cleft of the mouth very wide; maxillary<span class="pagenum" id="Page_586">[586]</span>
+developed, closely adherent to the intermaxillary. Teeth in
+a single series, unequal in size. Eye large. Ventrals small,
+inserted opposite or nearly opposite the dorsal. Dorsal fin
+short, on the hinder part of the body; adipose fin small; anal
+elongate, occupying the end of the tail; caudal emarginate.</p>
+</div>
+
+<p>Three species; small pelagic fishes from the Mediterranean and
+Atlantic.—<i>Sudis</i>, from the Mediterranean, has a dentition
+slightly different from that of <i>Paralepis</i>.</p>
+
+<div class="blockquot">
+
+<p>Plagyodus.—Body elongate, compressed, scaleless; snout much
+produced, with very wide cleft of the mouth. Intermaxillary very
+long and slender; maxillary thin, immovable. Teeth in the jaws
+and of the palate very unequal in size, the majority pointed
+and sharp, some very large and lanceolate. Eye large. Pectoral
+and ventral fins well developed; the rayed dorsal fin occupies
+the whole length of the back from the occiput to opposite the
+anal fin; adipose and anal fins of moderate size. Caudal forked.
+Branchiostegals six or seven.</p>
+</div>
+
+  <div class="figcenter" id="fig270">
+     <img
+    class="p1"   
+    src="images/fig270.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 270.—Plagyodus ferox.</p>
+  </div>
+
+<p>This is one of the largest and most formidable deep-sea fishes.
+One species only is well known, <i>P. ferox</i>, from Madeira and
+the sea off Tasmania; other species have been noticed from Cuba
+and the North Pacific, but it is not evident in what respects they
+differ specifically from <i>P. ferox</i>. This fish grows to a
+length of six feet, and from the stomach of one example have been
+taken several Octopods, Crustaceans,<span class="pagenum" id="Page_587">[587]</span> Ascidians, a young Brama,
+twelve young Boar-fishes, a Horse-mackerel, and one young of its own
+species. The stomach is coecal; the commencement of the intestine has
+extremely thick walls, its inner surface being cellular, like the
+lung of a reptile; a pyloric appendage is absent. All the bones are
+extremely thin, light, and flexible, containing very little earthy
+matter; singular is the development of a system of abdominal ribs,
+symmetrically arranged on both sides, and extending the whole length
+of the abdomen. Perfect specimens are rarely obtained on account of
+the want of coherence of the muscular and osseous parts, caused by the
+diminution of pressure when the fish reaches the surface of the water.
+The exact depth at which <i>Plagyodus</i> lives is not known; probably
+it never rises above a depth of 300 fathoms.</p>
+
+<p>The other less important genera belonging to this family are
+<i>Aulopus</i>, <i>Chlorophthalmus</i>, <i>Scopelosaurus</i>,
+<i>Odontostomus</i>, and <i>Nannobrachium</i>.</p>
+
+  <div class="figcenter" id="fig271" style="max-width: 365px">
+     <img
+    class="p1"   
+    src="images/fig271.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 271.—Pharyngeal bones and teeth of the Bream,
+Abramis brama.</p>
+  </div>
+
+
+<h6 class="smcap">Third Family—Cyprinidæ.</h6>
+
+<p><i>Body generally covered with scales; head naked. Margin of the upper
+jaw formed by the intermaxillaries. Belly rounded, or, if trenchant,
+without ossifications. No adipose fin. Stomach<span class="pagenum" id="Page_588">[588]</span> without blind sac.
+Pyloric appendages none. Mouth toothless; lower pharyngeal bones
+well developed, falciform, sub-parallel to the branchial arches,
+provided with teeth, which are arranged in one, two, or three series.
+Air-bladder large, divided into an anterior and posterior portion by a
+constriction, or into a right or left portion, enclosed in an osseous
+capsule. Ovarian sacs closed.</i></p>
+
+<p>The family of “Carps” is the one most numerously represented in the
+fresh waters of the Old World and of North America. Also numerous
+fossil remains are found in tertiary freshwater-formations, as in the
+limestones of Oeningen and Steinheim, in the lignites of Bonn, Stöchen,
+Bilin, and Ménat, in the marl slates and carbonaceous shales of Licata
+in Sicily, and of Padang in Sumatra, in corresponding deposits of Idaho
+in North America. The majority can be referred to existing genera:
+<i>Barbus</i>, <i>Thynnichthys</i>, <i>Gobio</i>, <i>Leuciscus</i>,
+<i>Tinca</i>, <i>Amblypharyngodon</i>, <i>Rhodeus</i>, <i>Cobitis</i>,
+<i>Acanthopsis</i>, only a few showing characters different from
+those of living genera: <i>Cyclurus</i>, <i>Hexapsephus</i>,
+<i>Mylocyprinus</i> (tertiary of North America).</p>
+
+<p>Most Carps feed on vegetable and animal substances; a few only are
+exclusive vegetable feeders. There is much less diversity of form and
+habits in this family than in the Siluroids; however, the genera are
+sufficiently numerous to demand a further subdivision of the family
+into groups.</p>
+
+<p>I. <span class="smcap">Catostomina.</span>—<i>Pharyngeal teeth in a single series,
+exceedingly numerous and closely set. Dorsal fin elongate, opposite to
+the ventrals; anal short, or of moderate length. Barbels none.</i></p>
+
+<p>These fishes are abundant in the lakes and rivers of North America,
+more than thirty species having been described, and many more
+named, by American ichthyologists. Two species are known from
+North-Eastern Asia. They are generally called “Suckers,” but their
+vernacular nomenclature is very<span class="pagenum" id="Page_589">[589]</span> arbitrary and confused. Some of
+the species which inhabit the large rivers and lakes grow to a
+length of three feet and a weight of fifteen pounds. The following
+genera may be distinguished:—<i>Catostomus</i>, “Suckers,”
+“Red-horses,” “Stone-rollers,” “White Mullets;” <i>Moxostoma</i>;
+<i>Sclerognathus</i>, “Buffaloes,” “Black Horses;” and
+<i>Carpiodes</i>, “Spear-fish,” “Sail-fish.”</p>
+
+<p>II. <span class="smcap">Cyprinina.</span>—<i>Anal fin very short, with not more than
+five or six, exceptionally seven, branched rays. Dorsal fin opposite
+ventrals. Abdomen not compressed. Lateral line running along the median
+line of the tail. Mouth frequently with barbels, never more than four
+in number. Pharyngeal teeth generally in a triple series in the Old
+World genera; in a double or single series in the North American forms,
+which are small and feebly developed. Air-bladder present, without
+osseous covering.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cyprinus.</span>—Scales large. Dorsal fin long, with a more
+or less strong serrated osseous ray; anal short. Snout rounded,
+obtuse, mouth anterior, rather narrow. Pharyngeal teeth, 3. 1.
+1.-1. 1. 3, molar-like. Barbels four.</p>
+</div>
+
+  <div class="figcenter" id="fig272">
+     <img
+    class="p1"   
+    src="images/fig272.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 272.—The Carp, Cyprinus carpio.</p>
+  </div>
+
+<p>The “Carp” (<i>C. carpio</i>, “Karpfen,” “La carpe,”) is originally
+a native of the East, and abounds in a wild state in China, where it
+has been domesticated for many centuries; thence it<span class="pagenum" id="Page_590">[590]</span> was transported
+to Germany and Sweden, and the year 1614 is assigned as the date of
+its first introduction into England. It delights in tranquil waters,
+preferring such as have a muddy bottom, and the surface partially
+shaded with plants. Its food consists of the larvæ of aquatic insects,
+minute testacea, worms, and the tender blades and shoots of plants. The
+leaves of lettuce, and other succulent plants of a similar kind, are
+said to be particularly agreeable to them, and to fatten them sooner
+than any other food. Although the Carp eats with great voracity when
+its supply of aliment is abundant, it can subsist for an astonishing
+length of time without nourishment. In the winter, when the Carps
+assemble in great numbers, and bury themselves among the mud and the
+roots of plants, they often remain for many months without eating. They
+can also be preserved alive for a considerable length of time out of
+the water, especially if care be taken to moisten them occasionally
+as they become dry. Advantage is often taken of this circumstance to
+transport them alive, by packing them among damp herbage or damp linen;
+and the operation is said to be unattended with any risk to the animal,
+especially if the precaution be taken to put a piece of bread in its
+mouth steeped in brandy!</p>
+
+<p>The fecundity of these fishes is very great, and their numbers
+consequently would soon become excessive but for the many enemies by
+which their spawn is destroyed. No fewer than 700,000 eggs have been
+found in the ovaries of a single Carp, and that, too, by no means an
+individual of the largest size. Their growth is very rapid, more so
+perhaps than that of any other Freshwater fish, and the size which they
+sometimes attain is very considerable. In certain lakes in Germany
+individuals are occasionally taken weighing thirty or forty pounds; and
+Pallas relates that they occur in the Volga five feet in length, and
+even of greater weight than the examples just alluded to. The largest
+of which we<span class="pagenum" id="Page_591">[591]</span> have any account is that mentioned by Bloch, taken near
+Frankfort-on-the-Oder, which weighed seventy pounds, and measured
+nearly nine feet in length,—a statement the accuracy of which is very
+much open to doubt.</p>
+
+<p>Like other domesticated animals the Carp is subject to variation; some
+individuals, especially when they have been bred under unfavourable
+circumstances, have a lean and low body; others are shorter and higher.
+Some have lost every trace of scales, and are called “Leather-carps;”
+others retain them along the lateral line and on the back only
+(“Spiegelkarpfen” of the Germans). Finally, in some are the fins much
+prolonged, as in certain varieties of the Gold-fish. Cross-breeds
+between the Carp and the Crucian Carp are of common occurrence.
+The Carp is much more esteemed as food in inland countries than in
+countries where the more delicate kinds of sea fishes can be obtained.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Carassius</span> differs from <i>Cyprinus</i> in lacking
+barbels; its pharyngeal teeth are compressed, in a single
+series, 4–4.</p>
+</div>
+
+<p>Two well-known species belong to this genus. The “Crucian Carp” (<i>C.
+carassius</i>, “Karausche”) is generally distributed over Central
+and Northern Europe, and extends into Italy and Siberia. It inhabits
+stagnant waters only, and is so tenacious of life that it will survive
+a lengthened sojourn in the smallest pools, where, however, it remains
+stunted; whilst in favourable localities it attains to a length of
+twelve inches. It is much subject to variation of form; very lean
+examples are commonly called “Prussian Carps.” Its usefulness consists
+in keeping ponds clean from a super-abundance of vegetable growth,
+and in serving as food for other more esteemed fishes. The second
+species is the “Gold-fish,” <i>Carassius auratus</i>. It is of very
+common occurrence in a wild state in China and the warmer parts of
+Japan, being entirely similar in colour to the Crucian Carp. In a
+domesticated<span class="pagenum" id="Page_592">[592]</span> state it loses the black or brown chromatophors, and
+becomes of a golden-yellow colour; perfect Albinos are comparatively
+scarcer. Many varieties and monstrosities have been produced during
+the long period of its domestication; the variety most highly priced
+at present being the so-called “Telescope-fish,” of which a figure is
+annexed. The Gold-fish is said to have been first brought to England
+in the year 1691, and is now distributed over nearly all the civilised
+parts of the world.</p>
+
+  <div class="figcenter" id="fig273">
+     <img
+    class="p1"   
+    src="images/fig273.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 273.—Cyprinus auratus, var.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Catla.</span>—Scales of moderate size. Dorsal fin without
+osseous ray, with more than nine branched rays, commencing
+nearly opposite to the ventrals. Snout broad, with the
+integuments very thin; there is no upper lip, the lower with a
+free continuous posterior margin. Symphysis of the mandibulary
+bones loose, with prominent tubercles. Mouth anterior. Barbels
+none. Gill-rakers very long, fine, and closely set. Pharyngeal
+teeth, 5. 3. 2.-2. 3. 5.</p>
+</div>
+
+<p>The “Catla” (<i>C. buchanani</i>), one of the largest Carps of the
+Ganges, growing to a length of more than three feet, and esteemed as
+food.</p>
+
+<p><span class="pagenum" id="Page_593">[593]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Labeo.</span>—Scales of moderate or small size. Dorsal
+fin without osseous ray, with more than nine branched rays,
+commencing somewhat in advance of the ventrals. Snout obtusely
+rounded, the skin of the maxillary region being more or less
+thickened, forming a projection beyond the mouth. Mouth
+transverse, inferior, with the lips thickened, each or one of
+them being provided with an inner transverse fold, which is
+covered with a deciduous horny substance forming a sharp edge,
+which, however, does not rest upon the bone as base, but is soft
+and movable. Barbels very small, two or four; the maxillary
+barbels more or less hidden in a groove behind the angle of the
+mouth. Anal scales not enlarged. Pharyngeal teeth uncinate, 5.
+4. 2.-2. 4. 5. Snout generally more or less covered with hollow
+tubercles.</p>
+</div>
+
+<p>About thirteen species are known from rivers of tropical Africa and the
+East Indies.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Discognathus.</span>—Scales of moderate size. Dorsal fin
+without osseous ray, with not more than nine branched rays,
+commencing somewhat in advance of the ventrals. Snout obtusely
+rounded, more or less depressed, projecting beyond the
+mouth, more or less tubercular. Mouth inferior, transverse,
+crescent-shaped; lips broad, continuous, with an inner sharp
+edge of the jaws, covered with horny substance on the lower jaw;
+upper lip more or less distinctly fringed; lower lip modified
+into a suctorial disk, with free anterior and posterior margins.
+Barbels two or four; if two, the upper are absent. Anal scales
+not enlarged. Pectoral fins horizontal. Pharyngeal teeth, 5. 4.
+2.-2. 4. 5.</p>
+</div>
+
+<p>A small fish (<i>D. lamta</i>), extremely abundant in almost all the
+mountain streams from Abyssinia and Syria to Assam.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Capoëta.</span>—Scales small, of moderate or large size.
+Dorsal fin with or without a strong osseous ray, with not
+more than nine branched rays. Snout rounded, with the mouth
+transverse and at its lower side; each mandible angularly bent
+inwards in front, the anterior mandibular edge being nearly
+straight, sharpish, and covered with a horny brown layer. No
+lower<span class="pagenum" id="Page_594">[594]</span> labial fold. Barbels two (rarely four), or entirely
+absent. Anal scales not conspicuously enlarged. Pharyngeal teeth
+compressed, truncated, 5 or 4. 3. 2–2. 3. 4 or 5.</p>
+</div>
+
+<p>Characteristic of the fauna of Western Asia; one species from
+Abyssinia. Of the fifteen species known <i>C. damascina</i> deserves to
+be specially mentioned, being abundant in the Jordan and other rivers
+of Syria and Asia Minor.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Barbus.</span>—Scales of small, moderate, or large size.
+Dorsal fin generally with the (third) longest simple ray
+ossified, enlarged, and frequently serrated; never, or only
+exceptionally, with more than nine branched rays, commencing
+opposite or nearly opposite to the root of the ventral fin. Eyes
+without adipose eyelid. Anal fin frequently very high. Mouth
+arched, without inner folds, inferior or anterior; lips without
+horny covering. Barbels short, four, two, or none. Anal scales
+not enlarged. Pharyngeal teeth 5. 4 or 3. 3 or 2.-2 or 3. 3 or
+4. 5. Snout but rarely with tubercles or pore-like grooves.</p>
+</div>
+
+<p>No other genus of Cyprinoids is composed of so many species as the
+genus of “Barbels,” about 200 being known from the tropical and
+temperate parts of the Old World; it is not represented in the New
+World. Although the species differ much from each other in the form
+of the body, number of barbels, size of the scales, strength of the
+first dorsal ray or spine, etc., the transition between the extreme
+forms is so perfect that no further generic subdivision should be
+attempted. Some attain a length of six feet, whilst others never exceed
+a length of two inches. The most noteworthy are the large Barbels of
+the Tigris (<i>B. subquincunciatus</i>, <i>B. esocinus</i>, <i>B.
+scheich</i>, <i>B. sharpeyi</i>); the common Barbel of Central Europe
+and Great Britain (<i>B. vulgaris</i>); the “Bynni” of the Nile (<i>B.
+bynni</i>); <i>B. canis</i> from the Jordan; the “Mahaseer” of the
+mountain streams of India (<i>B. mosal</i>), probably the largest of
+all species, the scales of which are sometimes as large as the palm of
+a hand. The small, large-scaled<span class="pagenum" id="Page_595">[595]</span> species are especially numerous in the
+East Indies and the fresh waters of Tropical Africa.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Thynnichthys.</span>—Scales small. Dorsal fin without an
+osseous ray, with not more than nine branched rays, commencing
+nearly opposite the ventrals. Head large, strongly compressed;
+eye without well-developed adipose membrane, in the middle of
+the depth of the head. Snout with the integuments very thin;
+there is no upper lip, and the lower jaw has a thin labial
+fold on the sides only. Mouth anterior and lateral; barbels
+none. Gill-rakers none; laminæ branchiales long, half as long
+as the post-orbital portion of the head; pseudobranchiæ none.
+Pharyngeal teeth lamelliform, with flat oblong crown, 5. 3 or 4.
+2–2. 4 or 3. 5, the teeth of the three series being wedged into
+one another.</p>
+</div>
+
+<p>Three species from the East Indies.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Oreinus.</span>—Scales very small. Dorsal fin with a strong
+osseous serrated ray, opposite to the ventrals. Snout rounded,
+with the mouth transverse, and at its lower side; mandibles
+broad, short, and flat, loosely joined together; margin of the
+jaw covered with a thick horny layer; a broad fringe-like lower
+lip, with free posterior margin. Barbels four. Vent and anal
+fin in a sheath, covered with enlarged tiled scales. Pharyngeal
+teeth pointed, more or less hooked, 5. 3. 2–2. 3. 5.</p>
+</div>
+
+<p>Three species from mountain streams of the Himalayas.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Schizothorax.</span>—Hill-barbels, with the same singular
+sheath on each side of the vent, as in the preceding genus; but
+they differ in having the mouth normally formed, with mandibles
+of the usual length and width.</p>
+</div>
+
+<p>Seventeen species are known from fresh waters of the Himalayas,
+and north of them. Other genera from the same region, and with
+the anal sheath, are <i>Ptychobarbus</i>, <i>Gymnocypris</i>,
+<i>Schizopygopsis</i>, and <i>Diptychus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gobio.</span>—Scales of moderate size; lateral line present.
+Dorsal fin short, without spine. Mouth inferior; mandible not
+projecting beyond the upper jaw when the mouth is open; both<span class="pagenum" id="Page_596">[596]</span>
+jaws with simple lips; a small but very distinct barbel at the
+angle of the mouth, quite at the extremity of the maxillary.
+Gill-rakers very short; pseudobranchiæ. Pharyngeal teeth, 5. 3
+or 2.—2 or 3. 5, hooked at the end.</p>
+</div>
+
+<p>The “Gudgeons” are small fishes of clear fresh waters of Europe;
+they are, like the barbels, animal feeders. In Eastern Asia they
+are represented by two closely allied genera, <i>Ladislavia</i> and
+<i>Pseudogobio</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ceratichthys.</span>—Scales of moderate or small size;
+lateral line present. Dorsal fin short, without spine, not or
+but slightly in advance of the ventrals. Mouth subinferior; the
+lower jaw does not project beyond the upper when the mouth is
+open; intermaxillaries protractile from below the maxillaries;
+both jaws with thickish lips; a small barbel at the angle of the
+mouth, quite at the extremity of the maxillary. Gill-rakers very
+short and few in number: pseudobranchiæ. Pharyngeal teeth 4–4.
+hooked at the end (sometimes 4, 1—1. 4).</p>
+</div>
+
+<p>About ten species are known from North America; they are small, and
+called “Chub” in the United States. <i>C. biguttatus</i> is, perhaps,
+the most widely-diffused Freshwater-fish in the United States, and
+common everywhere. Breeding males have generally a red spot on each
+side of the head.</p>
+
+<p>Other similar genera from the fresh waters of North America, and
+generally called “Minnows,” are <i>Pimephales</i> (the “Black
+Head”), <i>Hyborhynchus</i>, <i>Hybognathus</i>, <i>Campostoma</i>
+(the “Stone-lugger”), <i>Ericymba</i>, <i>Cochlognathus</i>,
+<i>Exoglossum</i> (the “Stone Toter” or “Cut-lips”), and
+<i>Rhinichthys</i> (the “Long-nosed Dace”).</p>
+
+<p>The remaining Old World genera belonging to the group <i>Cyprinina</i>
+are <i>Cirrhina</i>, <i>Dangila</i>, <i>Osteochilus</i>,
+<i>Barynotus</i>, <i>Tylognathus</i>, <i>Abrostomus</i>,
+<i>Crossochilus</i>, <i>Epalzeorhynchus</i>, <i>Barbichthys</i>,
+<i>Amblyrhynchichthys</i>, <i>Albulichthys</i>, <i>Aulopyge</i>,
+<i>Bungia</i>, and <i>Pseudorasbora</i>.</p>
+
+<p>III. <span class="smcap">Rohteichthyina.</span>—<i>Anal fin very short, with not more<span class="pagenum" id="Page_597">[597]</span>
+than six branched rays. Dorsal fin behind ventrals. Abdomen compressed.
+Lateral line running along the median line of the tail. Mouth without
+barbels. Pharyngeal teeth in a triple series.</i></p>
+
+<p>One genus and species only, <i>Rohteichthys microlepis</i>, from Borneo
+and Sumatra.</p>
+
+<p>IV. <span class="smcap">Leptobarbina.</span>—<i>Anal fin very short, with not more
+than six branched rays. Dorsal fin opposite to ventrals. Abdomen not
+compressed. Lateral line running in the lower half of the tail. Barbels
+present, not more than four in number. Pharyngeal teeth in a triple
+series.</i></p>
+
+<p>One genus and species only, <i>Leptobarbus hoevenii</i>, from Borneo
+and Sumatra.</p>
+
+<p>V. <span class="smcap">Rasborina.</span>—<i>Anal fin very short, with not more than six
+branched rays. Dorsal fin inserted behind the origin of the ventrals.
+Abdomen not compressed. Lateral line running along the lower half
+of the tail, if complete. Mouth sometimes with barbels, which are
+nevermore than four in number. Pharyngeal teeth in a triple, or single
+series. Air-bladder present, without osseous covering.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rasbora.</span>—Scales large, or of moderate size, there
+being generally four and a half longitudinal series of scales
+between the origin of the dorsal fin and the lateral line, and
+one between the lateral line and the ventral. Lateral line
+curved downwards. Dorsal fin with seven or eight branched rays,
+not extending to above the anal, which is seven-rayed. Mouth
+of moderate width, extending to the front margin of the orbit,
+with the lower jaw slightly prominent, and provided with three
+prominences in front, fitting into grooves of the upper jaw;
+barbels none, in one species two. Gill-rakers short, lanceolate.
+Pseudobranchiæ. Pharyngeal teeth in three series, uncinate.</p>
+</div>
+
+<p>Thirteen species of small size from the East Indian Continent and
+Archipelago, and from rivers on the east coast of Africa.</p>
+
+<p><span class="pagenum" id="Page_598">[598]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Amblypharyngodon.</span>—Scales small; lateral line
+incomplete. Dorsal fin without an osseous ray, with not more
+than nine branched rays, commencing a little behind the origin
+of the ventrals. Head of moderate size, strongly compressed;
+eye without adipose membrane; snout with the integuments very
+thin; there is no upper lip, and the lower jaw has a short
+labial fold on the sides only. Mouth anterior, somewhat directed
+upwards, with the lower jaw prominent. Barbels none. Gill-rakers
+extremely short; pseudobranchiæ. Pharyngeal teeth molar-like,
+with their crowns concave, 3. 2. 1.—1. 2. 3. Intestinal tract
+narrow, with numerous convolutions.</p>
+</div>
+
+<p>Three species of small size from the Continent of India.</p>
+
+<p>To the same group belong <i>Luciosoma</i>, <i>Nuria</i>, and
+<i>Aphyocypris</i>, from the same geographical region.</p>
+
+<p>VI. <span class="smcap">Semiplotina.</span>—<i>Anal fin short, with seven branched rays,
+not extending forwards to below the dorsal. Dorsal fin elongate, with
+an osseous ray. Lateral line running along the middle of the tail.
+Mouth sometimes with barbels.</i></p>
+
+<p>Two genera: <i>Cyprinion</i>, from Syria and Persia, and
+<i>Semiplotus</i> from Assam.</p>
+
+<p>VII. <span class="smcap">Xenocypridina.</span>—<i>Anal fin rather short, with seven or
+more branched rays, not extending forwards to below the dorsal fin.
+Dorsal short, with an osseous ray. Lateral line running along the
+middle of the tail. Mouth sometimes with barbels. Pharyngeal teeth in a
+triple or double series.</i></p>
+
+<p>Three genera: <i>Xenocypris</i> and <i>Paracanthobrama</i> from China;
+and <i>Mystacoleucus</i> from Sumatra.</p>
+
+<p>VIII. <span class="smcap">Leuciscina.</span>—<i>Anal fin short or of moderate length,
+with from eight to eleven branched rays, not extending forwards to
+below the dorsal. Dorsal fin short, without osseous ray. Lateral line,
+if complete, running along, or nearly in, the middle of the tail. Mouth
+generally without barbels. Pharyngeal teeth in a single or double
+series.</i></p>
+
+<p><span class="pagenum" id="Page_599">[599]</span></p><div class="blockquot">
+
+<p><span class="smcap">Leuciscus.</span>—Body covered with imbricate scales. Dorsal
+fin commencing opposite, rarely behind, the ventrals. Anal fin
+generally with from nine to eleven, rarely with eight (in small
+species only), and still more rarely with fourteen rays. Mouth
+without structural peculiarities; lower jaw not trenchant;
+barbels none. Pseudobranchiæ. Pharyngeal teeth conical or
+compressed, in a single or double series. Intestinal tract
+short, with only a few convolutions.</p>
+</div>
+
+<p>The numerous species of this genus are comprised under the name of
+“White-fish;” they are equally abundant in the northern temperate
+zone of both hemispheres, about forty species being known from the
+Old World, and about fifty from the New. The most noteworthy species
+of the former Fauna are the “Roach” (<i>L. rutilus</i>, see Fig. <a href="#fig21">21</a>,
+p. 50), common all over Europe north of the Alps; the “Chub” (<i>L.
+cephalus</i>), extending into Northern Italy and Asia Minor; the
+“Dace” (<i>L. leuciscus</i>), a companion of the Roach; the “Id” or
+“Nerfling” (<i>L. idus</i>), from the central and northern parts
+of Continental Europe, domesticated in some localities of Germany,
+in this condition assuming the golden hue of semi-albinism, like
+a Gold-fish, and then called the “Orfe;” the “Rudd,” or “Red-eye”
+(<i>L. erythrophthalmus</i>), distributed all over Europe and Asia
+Minor, and distinguished by its scarlet lower fins; the “Minnow”
+(<i>L. phoxinus</i>), abundant everywhere in Europe, and growing
+to a length of seven inches in favourable localities. The North
+American species are much less perfectly known; the smaller ones are
+termed “Minnows,” the larger “Shiner” or “Dace.” The most common are
+<i>L. cornutus</i> (Red-fin, Red Dace); <i>L. neogæus</i>, a minnow
+resembling the European species, but with incomplete lateral line;
+<i>L. hudsonius</i>, the “Spawn-eater” or “Smelt.”</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Tinca.</span>—Scales small, deeply embedded in the thick
+skin; lateral line complete. Dorsal fin short, its origin being
+opposite the ventral fin; anal short; caudal subtruncated.
+Mouth anterior; jaws with the lips moderately developed; a
+barbel at the angle of the mouth. Gill-rakers short, lanceolate;
+pseudobranchiæ<span class="pagenum" id="Page_600">[600]</span> rudimentary. Pharyngeal teeth 4 or 5.-5,
+cuneiform, slightly hooked at the end.</p>
+</div>
+
+  <div class="figcenter" id="fig274">
+     <img
+    class="p1"   
+    src="images/fig274.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 274.—The Tench (Tinca tinca).</p>
+  </div>
+
+<p>Only one species of “Tench” is known (<i>T. tinca</i>), found all over
+Europe in stagnant waters with soft bottom. The “Golden Tench” is only
+a variety of colour, an incipient albinism like the Gold-fish and Id.
+Like most other Carps of this group it passes the winter in a state of
+torpidity, during which it ceases to feed. It is extremely prolific,
+297,000 ova having been counted in one female; its spawn is of a
+greenish colour.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Leucosomus.</span>—Scales of moderate or small size; lateral
+line present. Dorsal fin commencing opposite, or nearly
+opposite, to the ventral. Anal fin short. Mouth anterior or
+sub-anterior; intermaxillaries protractile. A very small barbel
+at the extremity of the maxillary. Lower jaw with rounded
+margin, and with the labial folds well developed laterally.
+Gill-rakers short; pseudobranchiæ. Pharyngeal teeth in a double
+series.</p>
+</div>
+
+<p>A North American genus, to which belong some of the most common species
+of the United States. <i>L. pulchellus</i> (the “Fall-fish,” “Dace,”
+or “Roach”), one of the largest White-fishes of the Eastern States,
+attaining to a length of 18 inches, and abundant in the rapids of the
+larger rivers. <i>L. corporalis</i> (the “Chub”), common everywhere
+from New England to the Missouri region.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chondrostoma.</span>—Scales of moderate size or small.
+Lateral<span class="pagenum" id="Page_601">[601]</span> line terminating in the median line of the depth of the
+tail. Dorsal fin with not more than nine branched rays, inserted
+above the root of the ventrals. Anal fin rather elongate, with
+ten or more rays. Mouth inferior, transverse, lower jaw with a
+cutting edge, covered with a brown horny layer. Barbels none.
+Gill-rakers short, fine; pseudobranchiæ. Pharyngeal teeth 5 or
+6 or 7.-7 or 6 or 5, knife-shaped, not denticulated. Peritoneum
+black.</p>
+</div>
+
+<p>Seven species from the Continent of Europe and Western Asia.</p>
+
+<p>Other Old World genera belonging to the <i>Leuciscina</i> are
+<i>Myloleucus</i>, <i>Ctenopharyngodon</i>, and <i>Paraphoxinus</i>;
+from North America: <i>Mylopharodon</i>, <i>Meda</i>, <i>Orthodon</i>,
+and <i>Acrochilus</i>.</p>
+
+<p>IX. <span class="smcap">Rhodeina.</span>—<i>Anal fin of moderate length, with from nine
+to twelve branched rays, extending forwards to below the dorsal. Dorsal
+fin short, or of moderate length. Lateral line, if complete, running
+along or nearly in the middle of the tail. Mouth with very small, or
+without any barbels. Pharyngeal teeth in a single series.</i></p>
+
+<p>Very small roach-like fishes inhabiting chiefly Eastern Asia and
+Japan, one species (<i>Rh. amarus</i>) advancing into Central Europe.
+The thirteen species known have been distributed among four genera,
+<i>Achilognathus</i>, <i>Acanthorhodeus</i>, <i>Rhodeus</i>, and
+<i>Pseudoperilampus</i>. In the females a long external urogenital tube
+is developed annually during the spawning season. The European species
+is known in Germany by the name of “Bitterling.”</p>
+
+<p>X. <span class="smcap">Danionina.</span>—<i>Anal fin of moderate length or elongate,
+with not less, and generally more, than eight branched rays. Lateral
+line running along the lower half of the tail. Mouth with small, or
+without any, barbels. Abdomen not trenchant. Pharyngeal teeth in a
+triple or double series.</i></p>
+
+<p>Small fishes from the East Indian Continent, Ceylon, the East Asiatic
+Islands, and a few from East African Rivers,<span class="pagenum" id="Page_602">[602]</span> The genera belonging to
+this group are <i>Danio</i>, <i>Pteropsarion</i>, <i>Aspidoparia</i>,
+<i>Barilius</i>, <i>Bola</i>, <i>Scharca</i>, <i>Opsariichthys</i>,
+<i>Squaliobarbus</i>, and <i>Ochetobus</i>: altogether about forty
+species.</p>
+
+<p>XI. <span class="smcap">Hypophthalmichthyina.</span>—<i>Anal fin elongate. Lateral
+line running nearly along the median line of the tail. Mouth without
+barbels. Abdomen not trenchant. No dorsal spine. Pharyngeal teeth in a
+single series.</i></p>
+
+<p>One genus (<i>Hypophthalmichthys</i>) with two species from China.</p>
+
+<p>XII. <span class="smcap">Abramidina.</span>—<i>Anal fin elongate. Abdomen, or part of
+the abdomen, compressed.</i></p>
+
+  <div class="figcenter" id="fig275">
+     <img
+    class="p1"   
+    src="images/fig275.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 275.—The Bream ( Abramis brama).</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Abramis.</span>—Body much compressed, elevated, or oblong.
+Scales of moderate size. Lateral line present, running in the
+lower half of the tail. Dorsal fin short, with spine, opposite
+to the space between ventrals and anals. Lower jaw generally
+shorter, and rarely longer than the upper. Both jaws with simple
+lips, the lower labial fold being interrupted at the symphysis
+of the mandible. Upper jaw protractile. Gill-rakers rather
+short; pseudobranchiæ. The attachment of the branchial membrane
+to the isthmus takes place at some distance behind the vertical
+from the orbit. Pharyngeal teeth in one or two series, with a
+notch near the extremity. Belly behind the ventrals compressed
+into an edge, the scales not extending across it.</p>
+</div>
+
+<p>The “Breams” are represented in the temperate parts of<span class="pagenum" id="Page_603">[603]</span> both northern
+hemispheres; in Europe there occur the “Common Bream,” <i>A. brama</i>;
+the “Zope,” <i>A. ballerus</i>; <i>A. sapa</i>; the “Zärthe,” <i>A.
+vimba</i>; <i>A. elongatus</i>; the “White Bream,” <i>A. blicca</i>;
+<i>A. bipunctatus</i>. Of these <i>A. brama</i> and <i>A. blicca</i>
+are British; the former being one of the most common fishes, and
+sometimes attaining to a length of two feet. Crosses between these two
+species, and even with other Cyprinoids, are not rare. Of the American
+species <i>A. americanus</i> (“Shiner,” “Bream”) is common and widely
+distributed; like the European Bream it lives chiefly in stagnant
+waters or streams with a slow current.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Aspius.</span>—Body oblong; scales of moderate size; lateral
+line complete, terminating nearly in the middle of the depth of
+the tail. Dorsal fin short, without spine, opposite to the space
+between the ventrals and anal; anal fin elongate, with thirteen
+or more rays. Lower jaw more or less conspicuously projecting
+beyond the upper. Lips thin, simple, the lower labial fold being
+at the symphysis; upper jaw but little protractile. Gill-rakers
+short and widely set; pseudobranchiæ. The attachment of the
+branchial membrane to the isthmus takes place below the hind
+margin of the orbit. Pharyngeal teeth hooked, 5. 3.-3 or 2. 5 or
+4. Belly behind the ventrals compressed, the scales covering the
+edge.</p>
+</div>
+
+<p>Four species from Eastern Europe to China.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Alburnus.</span>—Body more or less elongate; scales of
+moderate size; lateral line present, running below the median
+line of the tail. Dorsal fin short, without spine, opposite to
+the space between ventrals and anal; anal fin elongate, with
+more than thirteen rays. Lower jaw more or less conspicuously
+projecting beyond the upper. Lips thin, simple, the lower labial
+fold being interrupted at the symphysis of the mandible. Upper
+jaw protractile. Gill-rakers slender, lanceolate, closely set;
+pseudobranchiæ. The attachment of the branchial membrane to
+the isthmus takes place below the hind margin of the orbit.
+Pharyngeal teeth in two series, hooked. Belly behind the
+ventrals compressed into an edge, the scales not extending
+across it.</p>
+</div>
+
+<p><span class="pagenum" id="Page_604">[604]</span></p>
+
+<p>“Bleak” are numerous in Europe and Western Asia, fifteen species being
+known. The common Bleak (<i>A. alburnus</i>) is found north of the
+Alps only, and represented by another species (<i>A. alburnellus</i>,
+“Alborella,” or “Avola”) in Italy.</p>
+
+<p>Of the other genera referred to this group, <i>Leucaspius</i> and
+<i>Pelecus</i> belong to the European Fauna; <i>Pelotrophus</i> is
+East African; all the others occur in the East Indies or the temperate
+parts of Asia, viz. <i>Rasborichthys</i>, <i>Elopichthys</i>,
+<i>Acanthobrama</i> (Western Asia), <i>Osteobrama</i>,
+<i>Chanodichthys</i>, <i>Hemiculter</i>, <i>Smiliogaster</i>,
+<i>Toxabramis</i>, <i>Culter</i>, <i>Eustira</i>, <i>Chela</i>,
+<i>Pseudolabuca</i>, and <i>Cachius</i>.</p>
+
+<p>XIII. <span class="smcap">Homalopterina.</span>—<i>Dorsal and anal fins short, the
+former opposite to ventrals. Pectoral and ventral fins horizontal, the
+former with the outer rays simple. Barbels six or none. Air-bladder
+absent. Pharyngeal teeth in a single series, from ten to sixteen in
+number.</i></p>
+
+<p>Inhabitants of hill-streams in the East Indies; they are of small size
+and abundant where they occur. Thirteen species are known belonging to
+the genera <i>Homaloptera</i>, <i>Gastromyzon</i>, <i>Crossostoma</i>,
+and <i>Psilorhynchus</i>.</p>
+
+<p>XIV. <span class="smcap">Cobitidina.</span>—<i>Mouth surrounded by six or more barbels.
+Dorsal fin short or of moderate length; anal fin short. Scales small,
+rudimentary, or entirely absent. Pharyngeal teeth in a single series,
+in moderate number. Air-bladder partly or entirely enclosed in a bony
+capsule. Pseudobranchiæ none</i>: Loaches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Misgurnus.</span>—Body elongate, compressed. No sub-orbital
+spine. Ten or twelve barbels, four belonging to the mandible.
+Dorsal fin opposite to the ventrals; caudal rounded.</p>
+</div>
+
+<p>Four species from Europe and Asia. <i>M. fossilis</i> is the largest
+of European Loaches, growing to a length of ten inches; it occurs in
+stagnant waters of eastern and southern<span class="pagenum" id="Page_605">[605]</span> Germany and northern Asia.
+In China and Japan it is replaced by an equally large species, <i>M.
+anguillicaudatus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Nemachilus.</span>—No erectile sub-orbital spine. Six
+barbels, none at the mandible. Dorsal fin opposite to the
+ventrals.</p>
+</div>
+
+<p>The greater number of Loaches belong to this genus; about fifty species
+are known from Europe and temperate Asia; such species as extend
+into tropical parts inhabit streams of high altitudes. Loaches are
+partial to fast-running streams with stony bottom, and exclusively
+animal feeders. In spite of their small size they are esteemed as food
+where they occur in sufficient abundance. The British species, <i>N.
+barbatulus</i>, is found all over Europe except Denmark and Scandinavia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cobitis.</span>—Body more or less compressed, elongate; back
+not arched. A small, erectile, bifid sub-orbital spine below
+the eye. Six barbels only on the upper jaw. Dorsal fin inserted
+opposite to ventrals. Caudal rounded or truncate.</p>
+</div>
+
+<p>Only three species are known, of which <i>C. tænia</i> occurs in
+Europe. It is scarce and very local in Great Britain.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Botia.</span>—Body compressed, oblong; back more or less
+arched. Eyes with a free circular eyelid; an erectile bifid
+sub-orbital spine. Six barbels on the upper jaw, sometimes two
+others at the mandibulary symphysis. Dorsal fin commencing
+in advance of the root of the ventrals; caudal fin forked.
+Air-bladder consisting of two divisions: the anterior enclosed
+in a partly osseous capsule, the posterior free, floating in the
+abdominal cavity.</p>
+</div>
+
+  <div class="figcenter" id="fig276" style="max-width: 308px">
+     <img
+    class="p1"   
+    src="images/fig276.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 276.—Botia rostrata. From Bengal.</p>
+  </div>
+
+<p>This genus is more tropical than any of the preceding, and the majority
+of the species (eight in number) are finely coloured. The more elevated
+form of their body, and the imperfect ossification of the capsules of
+the air-bladder, the divisions of which are not side<span class="pagenum" id="Page_606">[606]</span> by side, but
+placed in the longitudinal axis of the body, indicate likewise that
+this genus is more adapted for still waters of the plains than for the
+currents of hill-streams.</p>
+
+<p>Other genera from tropical India are <i>Lepidocephalichthys</i>,
+<i>Acanthopsis</i>, <i>Oreonectes</i> (hills near Hong-Kong),
+<i>Paramisgurnus</i> (Yan-tse-Kiang), <i>Lepidocephalus</i>,
+<i>Acanthophthalmus</i>, and <i>Apua</i>.</p>
+
+
+<h6 class="smcap">Fourth Family—Kneriidæ.</h6>
+
+<p><i>Body scaly, head naked. Margin of the upper jaw formed by the
+intermaxillaries. Dorsal and anal fins short, the former belonging
+to the abdominal portion of the vertebral column. Teeth none, either
+in the mouth or pharynx. Barbels none. Stomach siphonal; no pyloric
+appendages. Pseudobranchiæ none. Branchiostegals three; air-bladder
+long, not divided. Ovaries closed.</i></p>
+
+<p>Small loach-like fishes from fresh waters of tropical Africa; two
+species only, <i>Kneria angolensis</i> and <i>K. spekii</i>, are known.</p>
+
+
+<h6 class="smcap">Fifth Family—Characinidæ.</h6>
+
+<p><i>Body covered with scales, head naked; barbels none. Margin of the
+upper jaw formed by the intermaxillaries in the middle and by the
+maxillaries laterally. Generally a small adipose fin behind the dorsal.
+Pyloric appendages more or less numerous; air-bladder transversely
+divided into two portions, and communicating with the organ of hearing
+by means of the auditory ossicles. Pseudobranchiæ none.</i></p>
+
+<p>The fishes of this family are confined to the fresh waters of Africa,
+and especially of tropical America, where they replace the Cyprinoids,
+with which family, however, they have but little in common as far as
+their structural characteristics are concerned. Their co-existence
+in Africa with<span class="pagenum" id="Page_607">[607]</span> Cyprinoids proves only that that continent is nearer
+to the original centre, from which the distribution of Cyprinoids
+commenced than tropical America. The family includes herbivorous as
+well as strictly carnivorous forms; some are toothless, whilst others
+possess a most formidable dentition. The family contains so many
+diversified forms as to render a subdivision into groups necessary.
+They have not yet been obtained in fossiliferous strata.</p>
+
+<p>I. <span class="smcap">Erythrinina.</span>—<i>Adipose fin absent.</i></p>
+
+<p>The sixteen species of this group belong to the fauna of tropical
+America, and are referred to the genera <i>Macrodon</i>,
+<i>Erythrinus</i>, <i>Lebiasina</i>, <i>Nannostomus</i>,
+<i>Pyrrhulina</i>, and <i>Corynopoma</i>.</p>
+
+<p>II. <span class="smcap">Curimatina.</span>—<i>A short dorsal and an adipose fin;
+dentition imperfect. Tropical America.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Curimatus.</span>—Dorsal fin placed nearly in the middle of
+the body; anal rather short or of moderate length; ventrals
+below the dorsal. Body oblong or elevated, with the belly
+rounded or flattened before the ventrals. Cleft of the mouth
+transverse, lips none, margins of the jaws trenchant. No teeth
+whatever. Intestinal tract very long and narrow.</p>
+</div>
+
+<p>About twenty species are known, of rather small size.</p>
+
+<p>The other genera of this group have teeth, but they are either
+rudimentary or absent in some part of the jaws: <i>Prochilodus</i>,
+<i>Cænotropus</i>, <i>Hemiodus</i>, <i>Saccodon</i>, <i>Parodon</i>.</p>
+
+<p>III. <span class="smcap">Citharinina.</span>—<i>A rather long dorsal and an adipose fin;
+minute labial teeth. Tropical Africa.</i></p>
+
+<p>One genus only, <i>Citharinus</i>, with two species, is known. Common
+in the Nile, attaining to a length of three feet.</p>
+
+<p>IV. <span class="smcap">Anastomatina.</span>—<i>A short dorsal and an adipose fin; teeth
+in both jaws well developed; the gill-membranes grown to<span class="pagenum" id="Page_608">[608]</span> the isthmus;
+nasal openings remote from each other. Tropical America.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Leporinus.</span>—Dorsal fin placed nearly in the middle
+of the length of the body; anal short; ventrals below the
+dorsal. Body oblong, covered with scales of moderate size;
+belly rounded. Cleft of the mouth small, with the lips well
+developed; teeth in the intermaxillary and mandible, few in
+number, flattened, with the apex more or less truncated, and not
+serrated; the middle pair of teeth is the longest in both jaws;
+palate toothless.</p>
+</div>
+
+<p>This genus is generally distributed in the rivers east of the
+Andes; about twenty species are known, some of which, like <i>L.
+frederici</i>, <i>L. megalepis</i>, are very common. They are well
+marked by black bands or spots, and rarely grow to a length of two
+feet, being generally much smaller.—The other genera belonging to this
+group are <i>Anastomus</i> and <i>Rhytiodus</i>.</p>
+
+<p>V. <span class="smcap">Nannocharacina.</span>—<i>A short dorsal and an adipose fin;
+teeth in both jaws well developed; notched incisors. The gill-membranes
+are grown to the isthmus. Nostrils close together.</i></p>
+
+<p>One genus, <i>Nannocharax</i>, with two species only, from the Nile and
+Gaboon; very small.</p>
+
+<p>VI. <span class="smcap">Tetragonopterina.</span>—<i>A short dorsal and an adipose
+fin; the teeth in both jaws well developed, compressed, notched, or
+denticulated; the gill-membranes free from the isthmus, and the nasal
+openings close together. South America and Tropical Africa.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Alestes.</span>—The dorsal fin is placed in the middle of
+the length of the body, above or behind the ventrals; anal fin
+rather long. Body oblong, covered with scales of moderate or
+large size; belly rounded. Cleft of the mouth rather small.
+Maxillary teeth none; intermaxillary teeth in two series; those
+of the front series more or less compressed, more or less
+distinctly tricuspid; the teeth of the hinder series are broad,
+molar-like, each armed with several pointed tubercles. Teeth in
+the lower jaw in two series; those in the front series laterally
+compressed,<span class="pagenum" id="Page_609">[609]</span> broader behind than in front; the hinder series is
+composed of two conical teeth. All the teeth are strong, few in
+number.</p>
+</div>
+
+<p>Fourteen species from Tropical Africa; several inhabit the Nile, of
+which the “Raches” (<i>A. dentex</i> and <i>A. kotschyi</i>) are the
+most common.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Tetragonopterus.</span>—The dorsal fin is placed in the
+middle of the length of the body, above or immediately behind
+the ventrals; anal fin long. Body oblong or elevated, covered
+with scales of moderate size; belly rounded. Cleft of the mouth
+of moderate width. Anterior teeth strong, lateral teeth small.
+Intermaxillary and mandibulary teeth subequal in size, with
+a compressed and notched crown, the former in a double, the
+latter in a single series; maxillary with a few teeth near its
+articulation, rarely with the entire edge denticulated.</p>
+</div>
+
+<p>Of all the genera of this family <i>Tetragonopterus</i> is represented
+by the greatest number of species; about fifty are known. Some of them
+seem to have a very wide range, whilst others are merely local. All are
+of small size, rarely exceeding a length of eight inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chirodon.</span>—Dorsal fin placed in the middle of the
+length of the body, behind the ventrals; anal long or of
+moderate length. Body oblong, covered with scales of moderate
+size; lateral line not continued to the tail. Belly rounded
+before the ventrals. Cleft of the mouth narrow, maxillary short.
+A single series of small serrated teeth in the intermaxillary
+and mandibulary; maxillary teeth none.</p>
+</div>
+
+  <div class="figcenter" id="fig277">
+     <img
+    class="p1"   
+    src="images/fig277.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 277.—Chirodon alburnus.</p>
+  </div>
+
+<p>Three species of small size from various parts of South America; the
+species figured is represented of the natural size, and comes from the
+Upper Amazons.</p>
+
+<p><span class="pagenum" id="Page_610">[610]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Megalobrycon.</span>—Dorsal fin placed in middle of the
+length of the body, immediately behind the ventrals. Anal long.
+Abdomen rounded in front of, and somewhat compressed behind, the
+ventrals. Cleft of the mouth of moderate width. Teeth notched,
+in a triple series in the intermaxillary, and in a single in the
+maxillary and mandible; no other teeth behind the mandibulary
+teeth or on the palate. Scales of moderate size, with the free
+portion striated.</p>
+</div>
+
+<p>One species from the Upper Amazons (<i>M. cephalus</i>). Specimens more
+than one foot long have been obtained.</p>
+
+  <div class="figcenter" id="fig278" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig278.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 278.—Megalobrycon cephalus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gastropelecus.</span>—Dorsal fin placed behind the middle
+of the length of the body, above the anal; anal long;
+pectoral long; ventrals very small or rudimentary. Body
+strongly compressed, with the thoracic region dilated into a
+sub-semicircular disk. Scales of moderate size. Lateral line
+descending obliquely backwards towards the origin of the anal
+fin. The lower profile compressed into an acute ridge. Cleft
+of the mouth of moderate width; teeth compressed, tricuspid,
+in one or two series in the intermaxillary, and in a single in
+the mandible; maxillary with a few minute conical teeth; palate
+toothless.</p>
+</div>
+
+<p>Three specimens of this singular form are known from Brazil and the
+Guyanas; they are of very small size.</p>
+
+<p>The majority of the other genera belonging to this group are
+South American, viz. Piabucina, Scissor, <i>Pseudochalceus</i>,
+<i>Aphyocharax</i>, <i>Chalceus</i>, <i>Brycon</i>,
+<i>Chalcinopsis</i>, <i>Bryconops</i>, <i>Creagrutus</i>,
+<i>Chalcinus</i>, <i>Piabuca</i>, <i>Paragoniates</i>, and
+<i>Agoniates</i>; two only are African, viz. <i>Nannæthiops</i>,
+which represents the South American <i>Tetragonopterus</i>, and
+<i>Bryconæthiops</i>, which is allied to Brycon.</p>
+
+<p>VII. <span class="smcap">Hydrocyonina.</span>—<i>A short dorsal and an adipose fin</i>;<span class="pagenum" id="Page_611">[611]</span>
+<i>teeth in both jaws well developed and conical; gill membranes free
+from the isthmus; nasal openings close together. South America and
+Tropical Africa. Fishes of prey.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hydrocyon.</span>—The dorsal fin is in the middle of the
+length of the body, above the ventrals; anal of moderate length.
+Body oblong, compressed, covered with scales of moderate size;
+belly rounded. Cleft of the mouth wide, without lips; the
+intermaxillaries and mandibles are armed with strong pointed
+teeth, widely set and few in number; they are received in
+notches of the opposite jaw, and visible externally when the
+mouth is closed. Palate toothless. Cheeks covered with the
+enlarged sub-orbital bones. Orbit with an anterior and posterior
+adipose eyelid. Intestinal tract short.</p>
+</div>
+
+<p>Four species from Tropical Africa; two occur in the Nile, <i>H.
+forskalii</i> being abundant, and well known by the names “Kelb el
+bahr” and “Kelb el moyeh.” Their formidable dentition renders them most
+destructive to other fishes; they grow to a length of four feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cynodon.</span>—Dorsal fin placed behind, or nearly in, the
+middle of the length of the body, behind the ventrals; anal
+long. Head and body compressed, oblong, the latter covered
+with very small scales; belly compressed, keeled. Teeth in the
+intermaxillary, maxillary, and mandible in a single series,
+conical, widely set, of unequal size; a pair of very large
+canine teeth anteriorly in the lower jaw, received in two
+grooves on the palate; palate with patches of minute granulated
+teeth. The outer branchial arch without gill-rakers, but with
+very short tubercles.</p>
+</div>
+
+<p>Four species from Brazil and the Guyanas; they are as formidable fishes
+of prey as the preceding, and grow to the same size.</p>
+
+<p>With the exception of <i>Sarcodaces</i>, all the remaining
+genera of this group belong to the fauna of Tropical America,
+viz. <i>Anacyrtus</i>, <i>Hystricodon</i>, <i>Salminus</i>,
+<i>Oligosarcus</i>, <i>Xiphorhamphus</i>, and <i>Xiphostoma</i>.</p>
+
+<p><span class="pagenum" id="Page_612">[612]</span></p>
+
+<p>VIII. <span class="smcap">Distichodontina.</span>—<i>Dorsal fin rather elongate; adipose
+fin present. Gill-membranes attached to the isthmus; belly rounded.
+Tropical Africa.</i></p>
+
+<p>The species, ten in number, belong to one genus only
+(<i>Distichodus</i>), well known on the Nile under the name of
+“Nefasch.” They grow to a considerable size, being sometimes four feet
+long and one and a half foot deep. They are used as food.</p>
+
+<p>IX. <span class="smcap">Ichthyborina.</span>—<i>An adipose fin; number of dorsal rays
+increased (12–17); gill-membranes free from the isthmus. Belly rounded;
+canine teeth. Tropical Africa.</i></p>
+
+<p>Two genera only: <i>Ichthyborus</i> from the Nile, and <i>Phago</i>
+from West Africa. Small fishes of very rare occurrence.</p>
+
+<p>X. <span class="smcap">Crenuchina.</span>—<i>Dorsal fin rather elongate; an adipose
+fin. Gill-membranes free from the isthmus, with the belly rounded, and
+without canine teeth.</i></p>
+
+<p>This small group is represented in the Essequibo by a single species,
+<i>Crenuchus spilurus</i>, and by another in West Africa, <i>Xenocharax
+spilurus</i>.</p>
+
+<p>XI. <span class="smcap">Serrasalmonina.</span>—<i>Dorsal fin rather elongate; an adipose
+fin. Gill-membranes free from the isthmus; belly serrated. Tropical
+America.</i></p>
+
+<p>Although the fishes of this family do not attain any considerable size,
+the largest scarcely exceeding two feet in length, their voracity,
+fearlessness, and number renders them a perfect pest in many rivers
+of tropical America. In all, the teeth are strong, short, sharp,
+sometimes lobed incisors, arranged in one or more series; by means
+of them they cut off a mouthful of flesh as with a pair of scissors;
+and any animal falling into the water where these fishes abound is
+immediately attacked and cut in pieces in an incredibly short time.
+They assail persons entering the water, inflicting dangerous wounds
+before the victims are able to make their escape.<span class="pagenum" id="Page_613">[613]</span> In some localities
+it is scarcely possible to catch fishes with the hook and line, as the
+fish hooked is immediately attacked by the “Caribe” (as these fishes
+are called), and torn to pieces before it can be withdrawn from the
+water. The Caribes themselves are rarely hooked, as they snap the
+hook or cut the line. The smell of blood is said to attract at once
+thousands of these fishes to a spot. They are most abundant in the
+Brazils and Guyanas; some forty species are known, and referred to
+the genera <i>Mylesinus</i>, <i>Serrasalmo</i>, <i>Myletes</i>, and
+<i>Catoprion</i>.</p>
+
+  <div class="figcenter" id="fig279" style="max-width: 474px">
+     <img
+    class="p1"   
+    src="images/fig279.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 279.—Serrasalmo scapularis, from the Essequibo.</p>
+  </div>
+
+
+<h6 class="smcap">Sixth Family—Cyprinodontidæ.</h6>
+
+<p><i>Head and body covered with scales; barbels none. Margin of the upper
+jaw formed by the intermaxillaries only. Teeth in both jaws; upper
+and lower pharyngeals with cardiform teeth. Adipose fin none; dorsal
+fin situated on the hinder half of the body. Stomach without blind
+sac; pyloric appendages none. Pseudobranchiæ none; air-bladder simple,
+without ossicula auditus.</i></p>
+
+<p>Small fishes, inhabiting fresh, brackish, and salt water of Southern
+Europe, Africa, Asia, and America. The majority<span class="pagenum" id="Page_614">[614]</span> are viviparous; and to
+facilitate copulation the anal fin of the adult male of many species
+is modified into a copulatory organ, which is probably (partially at
+least) introduced into the vulva of the female; but it is uncertain
+whether it serves to conduct the semen, or merely to give the male
+a firmer hold of the female during the act. Also secondary sexual
+differences are developed in the Cyprinodonts; the males are always
+the smaller, sometimes several times smaller than the females, quite
+diminutive; and they are perhaps the smallest fishes in existence. The
+fins generally are more developed in the males, and the coloration is
+frequently different also. Some species are carnivorous; others live
+on the organic substances mixed with mud. Fossil remains have been
+found in tertiary strata, all apparently referable to the existing
+genus <i>Cyprinodon</i>; they occur near Aix in Provence, in the marl
+of Gesso, St. Angelo, in the Brown coal near Bonn, near Frankfort,
+and in the freshwater-chalk of Oeningen. In the latter locality a
+<i>Poecilia</i> occurs likewise.</p>
+
+<p>The genera can be divided into two groups:</p>
+
+<p>I. <span class="smcap">Cyprinodontidæ Carnivoræ.</span>—<i>The bones of each ramus of
+the mandible are firmly united; intestinal tract short, or but little
+convoluted. Carnivorous or insectivorous.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cyprinodon.</span>—Cleft of the mouth small, developed
+laterally and horizontally. Snout short. Teeth of moderate size,
+incisor-like, notched, in a single series. Scales rather large.
+Origin of the anal fin behind that of the dorsal in both sexes,
+both fins being larger in the male than in the female. Anal not
+modified into a sexual organ.</p>
+</div>
+
+<p>Seven species occur in the Mediterranean region, all of which seem
+able to live in briny springs or pools, the water of which contains a
+much greater percentage of salts than sea-water, as the brine-springs
+near the Dead Sea or in the Sahara. They are as little affected by
+the high temperature of some of these springs (91°), for instance
+of that at Sidi<span class="pagenum" id="Page_615">[615]</span> Ohkbar in the Sahara. Like other fishes living in
+limited localities or concealing themselves in mud, Cyprinodonts lose
+sometimes their ventral fins; such specimens have been described as
+<i>Tellia</i>. The species of the New World are less known than those
+of the Old, but not less numerous.</p>
+
+<p>Allied to Cyprinodon are <i>Fitzroyia</i> from Monte Video, and
+<i>Characodon</i> from Central America.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Haplochilus.</span>—Snout flat, both jaws being much
+depressed, and armed with a narrow band of villiform teeth. Body
+oblong, depressed anteriorly, compressed posteriorly. Dorsal fin
+short, commencing behind the origin of the anal, which is more
+or less elongate.</p>
+</div>
+
+<p>Twenty species from the East Indies, tropical Africa, and temperate and
+tropical America.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Fundulus.</span>—Cleft of the mouth of moderate width,
+developed laterally and horizontally. Snout of moderate length.
+Teeth in a narrow band, those of the outer series being largest,
+conical. Scales of moderate size. Dorsal fin commencing before
+or opposite the origin of the anal. Sexes not differentiated.</p>
+</div>
+
+<p>“Killifish,” abundant in the New World, where about twenty species have
+been found; <i>F. heteroclitus</i>, <i>majalis</i>, <i>diaphanus</i>,
+being common on the Atlantic coast of the United States; from the
+Old World two species only are known, viz. <i>F. hispanicus</i>
+from Spain, and <i>F. orthonotus</i> from the east coast of Africa.
+Allied to <i>Fundulus</i> are the South American <i>Limnurgus</i>,
+<i>Lucania</i>, <i>Rivulus</i>, and <i>Cynolebias</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Orestias.</span>—Ventral fins none. Cleft of the mouth
+of moderate width, directed upwards, with the lower jaw
+prominent, and with the upper protractile. Both jaws with a
+narrow band Of small conical teeth. Scales rather small or
+of moderate size, those on the head and upper part of the
+trunk frequently enlarged, plate-like, and granulated. Dorsal
+and anal fins moderately developed, opposite to each other.
+Sexes not differentiated by modification of the anal fin. The
+gill-membranes of<span class="pagenum" id="Page_616">[616]</span> both sides are united for a short distance,
+and not attached to the isthmus.</p>
+</div>
+
+<p>Inhabitants of Lake Titicaca and other elevated sheets of water on the
+Cordilleras of Peru and Bolivia, between the 14th and 19th degrees of
+latitude, at an elevation of 13,000 and 14,000 feet above the level
+of the sea. Singularly, the fishes of this outlying genus attain to a
+greater size than any other members of this family, being about eight
+inches long and comparatively bulky. They are considered a delicacy.
+Six species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Jenynsia.</span>—Cleft of the mouth small, developed
+laterally and horizontally; snout not produced. Both jaws with a
+series of tricuspid teeth of moderate size. Scales of moderate
+size. The origin of the anal fin is, in both sexes, behind that
+of the dorsal, although the anal of the male is modified into
+an intromittent organ, in which scarcely any of the rays remain
+distinct.</p>
+</div>
+
+<p>One species from Maldonado.</p>
+
+  <div class="figcenter" id="fig280" style="max-width: 643px">
+     <img
+    class="p1"   
+    src="images/fig280.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 280.—Gambusia punctata, from Cuba. A. Male; B. Female.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gambusia.</span>—Cleft of the mouth developed laterally and
+horizontally. Snout not produced, with the lower jaw more or
+less prominent. Both jaws with a band of teeth, those of the
+outer series being strongest and conical. Scales rather large.
+Origin of the anal fin more or less in advance of that of the
+dorsal. Anal fin of the male modified into an intromittent organ
+and much advanced.</p>
+</div>
+
+<p><span class="pagenum" id="Page_617">[617]</span></p>
+
+<p>Eight species from the West Indies and the southern parts
+of South America.—Allied genera are the Central American
+<i>Pseudoxiphophorus</i> and <i>Belonesox</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Anableps.</span>—Head broad and depressed, with the
+supraorbital part very much raised. Body elongate, depressed
+anteriorly and compressed posteriorly. Cleft of the mouth
+horizontal, of moderate width, the mandible being short; upper
+jaw protractile. Both jaws armed with a band of villiform teeth,
+those of the outer series being largest and somewhat movable.
+The integuments of the eye are divided into an upper and lower
+portion by a dark-coloured transverse band of the conjunctiva;
+also the pupil is completely divided into two by a pair of lobes
+projecting from each side of the iris. Scales rather small or of
+moderate size. Dorsal and anal fins short, the former behind the
+latter. The anal fin of the male is modified into a thick and
+long scaly conical organ with an orifice at its extremity.</p>
+</div>
+
+<p>Three species from tropical America. They are the longest Cyprinodonts,
+attaining to the length of nearly twelve inches. Their peculiar habit
+of swimming with part of the head out of the water has been noticed
+above (p. 113).</p>
+
+<p>II. <span class="smcap">Cyprinodontidæ Limnophagæ.</span>—<i>The bones of each ramus of
+the mandible are but loosely joined; intestinal tract with numerous
+circumvolutions. Sexes differentiated. Mud-eating. Tropical America.</i></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Poecilia.</span>—Cleft of the mouth small, transverse;
+mandible very short. Both jaws with a narrow band of minute
+teeth. Scales rather large. Origin of the anal fin generally
+nearly opposite to that of the dorsal fin in the female, but
+in the male it is modified into an intromittent organ and much
+advanced. Dorsal fin short, with not more than eleven rays.</p>
+</div>
+
+<p>Sixteen species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Mollienesia.</span>—Differing from <i>Poecilia</i> in having
+a larger dorsal fin, with twelve or more rays.</p>
+</div>
+
+<p>Five species. The males are most beautifully coloured, and their dorsal
+fin is much enlarged. In one species (<i>M.<span class="pagenum" id="Page_618">[618]</span> hellerii</i>), besides,
+the lower caudal rays of the mature male are prolonged into a long,
+sword-shaped, generally black and yellow appendage.</p>
+
+<p>Two other genera belong to this group: <i>Platypoecilus</i> and
+<i>Girardinus</i>.</p>
+
+
+<h6 class="smcap">Seventh Family—Heteropygii.</h6>
+
+<p><i>Head naked; body covered with very small scales; barbels none.
+Margin of the upper jaw formed, by the intermaxillaries. Villiform
+teeth in the jaws and on the palate. Adipose fin none. Dorsal fin
+belonging to the caudal portion of the vertebral column, opposite to
+the anal. Ventral fins rudimentary or absent. Vent situated before the
+pectorals. Stomach coecal; pyloric appendages present. Pseudobranchiæ
+none; air-bladder deeply notched anteriorly.</i></p>
+
+<p>To this small family, which is closely allied to the Cyprinodonts and
+Umbridæ, belongs the famous Blind Fish of the Mammoth Cave in Kentucky,
+<i>Amblyopsis spelæus</i>. It is destitute of external eyes, and the
+body is colourless; although the eyes, with the optic nerve, are quite
+rudimentary, the optic lobes are as much developed as in fishes with
+perfect eyes. The loss of vision is compensated by the acuteness of
+its sense of hearing, as well as by a great number of tactile papillæ,
+arranged on transverse ridges on the head, and provided with nervous
+filaments coming from the fifth pair. The ovary is single, and the
+fish is viviparous, like the Cyprinodonts. It seems to occur in all
+the subterranean rivers that flow through the great limestone region
+underlying the carboniferous rocks in the central portion of the United
+States. As in <i>Cyprinodon</i>, so in this genus, specimens occur
+without ventral fins; they have been called <i>Typhlichthys</i>. The
+largest size to which <i>Amblyopsis</i> grows is five inches.</p>
+
+<p><i>Chologaster</i> is closely allied, but provided with small<span class="pagenum" id="Page_619">[619]</span> external
+eyes; its body is coloured, but it is destitute of ventrals. It was
+found once in a rice field in South Carolina.</p>
+
+<div class="blockquot">
+
+<p>[See Tellkampf, Müll. Arch. 1844, p. 381; Packard and Putnam,
+“The Mammoth Cave and its Inhabitants.” Salem. 1872. 8<sup>o</sup>.]</p>
+</div>
+
+
+<h6 class="smcap">Eighth Family—Umbridæ.</h6>
+
+<p><i>Head and body covered with scales; barbels none. Margin of the upper
+jaw formed by the intermaxillaries mesially, and by the maxillaries
+laterally. Adipose fin none; the dorsal fin belongs partly to the
+abdominal portion of the vertebral column. Stomach siphonal; pyloric
+appendages none; pseudobranchiæ glandular, hidden; air-bladder
+simple.</i></p>
+
+<p>Two small species only are known: <i>Umbra krameri</i> from Austria
+and Hungary, and <i>Umbra limi</i>, locally distributed in the United
+States; called “Hunds-fish” in Germany, “Dog-fish” or “Mud-fish” in
+America.</p>
+
+
+<h6 class="smcap">Ninth Family—Scombresocidæ.</h6>
+
+<p><i>Body covered with scales; a series of keeled scales along each side
+of the belly. Margin of the upper jaw formed by the intermaxillaries
+mesially, and by the maxillaries laterally. Lower pharyngeals united
+into a single bone. Dorsal fin opposite the anal, belonging to the
+caudal portion of the vertebral column. Adipose fin none. Air-bladder
+generally present, simple, sometimes cellular, without pneumatic
+duct. Pseudobranchiæ hidden, glandular. Stomach not distinct from the
+intestine, which is quite straight, without appendages.</i></p>
+
+<p>The fishes of this family are chiefly marine, some living in the open
+ocean, whilst others have become acclimatised in fresh water; many of
+the latter are viviparous, all the marine forms being oviparous. They
+are found in all the temperate and tropical zones. Carnivorous.</p>
+
+<p>This family is represented in the strata of Monte Bolca by rare
+remains of a fish named <i>Holosteus</i>, allied to <i>Belone</i> or<span class="pagenum" id="Page_620">[620]</span>
+<i>Scombresox</i>, and by a species of <i>Belone</i> in the miocene of
+Licata.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Belone.</span>—Both jaws are prolonged into a long slender
+beak. All the dorsal and anal rays connected by membrane.</p>
+</div>
+
+<p>The long upper jaw of the “Gar-pike” is formed by the intermaxillaries,
+which are united by a longitudinal suture. Both jaws are beset with
+asperities, and with a series of longer, conical-pointed, widely-set
+teeth. Skimming along the surface of the water, the Gar-pike seize
+with these long jaws small fish as a bird would seize them with its
+beak; but their gullet is narrow, so that they can swallow small fish
+only. They swim with an undulating motion of the body; although they
+are in constant activity, their progress through the water is much
+slower than that of the Mackerels, the shoals of which sometimes
+appear simultaneously with them on our coasts. Young specimens are
+frequently met in the open ocean; when very young their jaws are not
+prolonged, and during growth the lower jaw is much in advance of the
+upper, so that these young fishes resemble a <i>Hemirhamphus</i>. About
+fifty species are known from tropical and temperate seas, <i>Belone
+belone</i> being a common fish on the British coast. Its bones, like
+those of all its congeners, are green; and therefore the fish, although
+good eating, is disliked by many persons. Some species attain a length
+of five feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Scombresox.</span>—Both jaws are prolonged into a long
+slender beak. A number of detached finlets behind the dorsal and
+anal fins.</p>
+</div>
+
+<p>The “Saury” or “Skipper” resemble the Gar-pike, but the teeth in the
+jaws are minute; they seem to feed chiefly on soft pelagic animals. In
+their habits they are still more pelagic; and the young, in which the
+beak is still undeveloped, are met with everywhere in the open ocean,
+in the<span class="pagenum" id="Page_621">[621]</span> Atlantic as well as in the Pacific. The European species,
+<i>Sc. saurus</i>, is not rare on the British coast; four other species
+have been described, closely allied to <i>Sc. saurus</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hemirhamphus.</span>—The lower jaw only is prolonged into a
+long slender beak.</p>
+</div>
+
+<p>In the young both jaws are short; the upper is never prolonged, the
+intermaxillaries forming a triangular, more or less convex, plate.
+The “Half-beaks” are common between and near the tropics; some forty
+species are known, none of which attain to the same length as the
+Gar-pike, scarcely ever exceeding a length of two feet. Some of the
+tropical species live in fresh water only; they are of small size and
+viviparous.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Arrhamphus.</span>—Mouth formed as in <i>Hemirhamphus</i>,
+except that the lower jaw is not produced into a beak. Pectoral
+fins of moderate length.</p>
+</div>
+
+<p>One species (<i>A. sclerolepis</i>) from the coast of Queensland
+(not New Zealand); it may be regarded as a <i>Hemirhamphus</i>, with
+retarded development of the lower jaw.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Exocoetus.</span>—Jaws short, intermaxillaries and
+maxillaries separate. Teeth minute, rudimental, and sometimes
+absent. Body moderately oblong, covered with rather large
+scales. Pectorals very long, an organ of flying.</p>
+</div>
+
+  <div class="figcenter" id="fig281">
+     <img
+    class="p1"   
+    src="images/fig281.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 281.—Flying Fish; Exocoetus callopterus.</p>
+  </div>
+
+<p>Forty-four different kinds of “Flying-fishes” are known from tropical
+and sub-tropical seas; some have a very wide range, whilst others seem
+to remain within one particular<span class="pagenum" id="Page_622">[622]</span> part of the ocean; thus, the species
+figured, <i>E. callopterus</i>, has been hitherto found on the Pacific
+side of the isthmus of Panama only. Their usual length is about 10 or
+12 inches, but specimens of 18 inches have been caught. They always
+live in shoals, and their numbers at certain times and localities are
+immense; thus, at Barbadoes many boats engage in their capture, as
+they are excellent eating. The pectorals are in the various species of
+unequal length; in some they extend to the anal fin only; in others
+(and these are the best fliers) to the caudal. A few have curious,
+barbel-like appendages at the lower jaw, which may disappear with age
+or be persistent throughout life. The literature on the subject of
+Flying-fishes is very extensive, and great diversity of opinion exists
+among observers as regards the mode and power of their flight; but
+the most reliable agree that the fishes do not leave the water for
+the purpose of catching insects (!), and that they are unable to move
+their fins in the manner of a bat or bird, or to change voluntarily the
+direction of their flight, or to fly beyond a very limited distance.
+The most recent enquiries are those of K. Möbius (“Die Bewegungen
+der Fliegenden Fische durch die Luft,” Leip. 1878, 8vo), the chief
+results of which may be summed up thus: Flying-fish are more frequently
+observed in rough weather and in a disturbed sea than during calm; they
+dart out of the water when pursued by their enemies, or frightened
+by an approaching vessel, but frequently also without any apparent
+cause, as is also observed in many other fishes; and they rise without
+regard to the direction of the wind or waves. The fins are kept quietly
+distended, without any motion, except an occasional vibration caused
+by the air whenever the surface of the wing is parallel with the
+current of the wind. Their flight is rapid, but gradually decreasing
+in velocity, greatly exceeding that of a ship going 10 miles an hour,
+and a distance of 500 feet. Generally, it<span class="pagenum" id="Page_623">[623]</span> is longer when the fishes
+fly against than with or at an angle to the wind. Any vertical or
+horizontal deviation from a straight line is not caused at the will of
+the fish, but by currents of the air; thus they retain a horizontally
+straight course when flying with or against the wind, but are carried
+towards the right or left whenever the direction of the wind is at an
+angle with that of their flight. However, it sometimes happens that
+the fish during its flight immerses its caudal fin in the water, and
+by a stroke of its tail turns towards the right or left. In a calm the
+line of their flight is always also vertically straight, or rather
+parabolic, like the course of a projectile, but it may become undulated
+in a rough sea, when they are flying against the course of the waves;
+they then frequently overtop each wave, being carried over it by the
+pressure of the disturbed air. Flying-fishes often fall on board of
+vessels, but this never happens during a calm, or from the lee side,
+but during a breeze only, and from the weather side. In daytime they
+avoid a ship, flying away from it; but during the night, when they
+are unable to see, they frequently fly against the weather-board,
+where they are caught by the current of air, and carried upwards to a
+height of 20 feet above the surface of the water, while, under ordinary
+circumstances, they keep close to it. All these observations point
+clearly to the fact that any deflection from a straight course is due
+to external circumstances, and not to voluntary action on the part of
+the fish.</p>
+
+
+<h6 class="smcap">Tenth Family—Esocidæ.</h6>
+
+<p><i>Body covered with scales; barbels none. Margin of the upper jaw
+formed by the intermaxillaries mesially, and by the maxillaries
+laterally. Adipose fin none; the dorsal fin belongs to the caudal
+portion of the vertebral column. Stomach without blind sac; pyloric
+appendages none. Pseudobranchiæ glandular, hidden; air-bladder simple;
+gill-opening very wide.</i></p>
+
+<p><span class="pagenum" id="Page_624">[624]</span></p>
+
+<p>This family includes one genus only, <i>Esox</i>, the “Pikes,”
+inhabitants of the fresh waters of the temperate parts of Europe, Asia,
+and America. The European species, <i>E. lucius</i>, inhabits all three
+continents, but the North American waters harbour five, or perhaps
+more, other species, of which the “Muskellunge,” or “Maskinonge” (<i>E.
+estor</i>) of the Great Lakes attains to the same large size as the
+common Pike. The other species are generally called “Pickerell” in the
+United States.</p>
+
+  <div class="figcenter" id="fig282">
+     <img
+    class="p1"   
+    src="images/fig282.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 282.—The Pike. (Esox lucius.)</p>
+  </div>
+
+<p>Fossil Pike, belonging to the existing genus, have been found in the
+freshwater-chalk of Oeningen, and in the diluvial marl of Silesia.
+Remains of the common Pike occur in abundance in quaternary deposits.</p>
+
+
+<h6 class="smcap">Eleventh Family—Galaxiidæ.</h6>
+
+<p><i>Body naked, barbels none. Margin of the upper jaw chiefly formed
+by the intermaxillaries, which are short, and continued by a thick
+lip, behind which are the maxillaries. Belly rounded; adipose fin
+none; dorsal opposite to anal. Pyloric appendages in small number.
+Air-bladder large, simple; pseudobranchiæ none. The ova fall into the
+cavity of the abdomen before exclusion.</i></p>
+
+<p>Small freshwater fishes of the southern hemisphere, belonging to
+two genera, <i>Galaxias</i> and <i>Neochanna</i>. Of the<span class="pagenum" id="Page_625">[625]</span> former
+genus five species are found in New Zealand, where this type is most
+developed, three in New South Wales, two in Tasmania, and four in the
+southern extremity of South America. Their native name in New Zealand
+is “Kokopu,” and they were dignified with the name of “Trout” by the
+settlers before the introduction of true Salmonidæ. They rarely exceed
+a length of eight inches. <i>Neochanna</i> is a degraded form of
+<i>Galaxias</i>, from which it differs by the absence of ventral fins.
+This fish has hitherto been found only in burrows, which it excavates
+in clay or consolidated mud, at a distance from water.</p>
+
+  <div class="figcenter" id="fig283" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig283.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 283.—Galaxias truttaceus, from Tasmania.</p>
+  </div>
+
+
+<h6 class="smcap">Twelfth Family—Mormyridæ.</h6>
+
+<p><i>Body and tail scaly; head scaleless; barbels none. The margin of
+the upper jaw is formed in the middle by the intermaxillaries, which
+coalesce into a single bone, and laterally by the maxillaries. Sub-
+and inter-operculum present, the latter very small. On each side of
+the single parietal bone a cavity leading into the interior of the
+skull, and covered with a thin bony lamella. All the fins are well
+developed, in</i> Mormyrus; <i>or caudal, anal, and ventral fins are
+absent, in</i> Gymnarchus. <i>No adipose fin. Pseudobranchiæ none;
+gill-openings reduced to a short slit. Air-bladder simple. Two coeca
+pylorica behind the stomach.</i></p>
+
+<p>This family is characteristic of the freshwater fauna of tropical
+Africa. Of <i>Mormyrus</i> (including <i>Hyperopisus</i> and<span class="pagenum" id="Page_626">[626]</span>
+<i>Mormyrops</i>), fifty-one species are known, of which eleven occur
+in the Nile. Some attain a length of three or four feet, others remain
+small. Their flesh is said to have an excellent flavour. The species
+figured (and probably other allied species) was an object of veneration
+to the ancient Egyptians, and, therefore, frequently occurs in their
+emblematic inscriptions. They abstained from eating it because it was
+one of three different kinds of fishes accused of having devoured a
+member of the body of Osiris, which, therefore, Isis was unable to
+recover when she collected the rest of the scattered members of her
+husband.</p>
+
+  <div class="figcenter" id="fig284">
+     <img
+    class="p1"   
+    src="images/fig284.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 284.—Mormyrus oxyrhynchus.</p>
+  </div>
+
+<p>The <i>Mormyri</i> possess a singular organ on each side of the tail,
+without electric functions, but evidently representing a transitional
+condition from muscular substance to an electric organ. It is an oblong
+capsule divided into numerous compartments by vertical transverse
+septa, and containing a gelatinous substance. The <i>Mormyri</i> differ
+much with regard to the extent of the dorsal and anal fins, the former
+sometimes occupying the greater portion of the length of the back,
+sometimes being much shorter and limited to the tail. In some the snout
+is short and obtuse, in others long and decurved, with or without
+appendage.</p>
+
+<p>Of <i>Gymnarchus</i> one species only is known, <i>G. niloticus</i>,
+which occurs in the Nile and West African rivers, and attains a
+length of six feet. The form of its body is eel-like, and each jaw
+is armed with a series of incisor-like teeth.<span class="pagenum" id="Page_627">[627]</span> Like <i>Mormyrus</i>,
+<i>Gymnarchus</i> possesses a pseudo-electric organ, thickest on the
+tail, tapering in front, and extending nearly to the head. It consists
+of four membranaceous tubes intimately connected with the surrounding
+muscles, and containing prismatic bodies arranged in the manner
+of a paternoster. The air-bladder of Gymnarchus is cellular, very
+extensible, and communicates with the dorsal side of the œsophagus by a
+duct possessing a sphincter.</p>
+
+<div class="blockquot">
+
+<p>[See <i>Erdl</i>, Münchner Gelehrte Anzeigen, 1846, xxiii., and
+<i>Hyrtl</i>, Denkschr. Akad. Wiss. Wien. 1856. xii.]</p>
+</div>
+
+
+<h6 class="smcap">Thirteenth Family—Sternoptychidæ.</h6>
+
+<p><i>Body naked, or with very thin deciduous scales; barbels none. Margin
+of the upper jaw formed by the maxillary and intermaxillary, both
+of which are toothed; opercular apparatus not completely developed.
+Gill-opening very wide; pseudobranchiæ present or absent; air-bladder
+simple, if present. Adipose fin present, but generally rudimentary.
+Series of phosphorescent bodies along the lower parts. The eggs are
+enclosed in the sacs of the ovarium, and excluded by oviducts.</i></p>
+
+<p>Pelagic and Deep-sea fishes of small size.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sternoptyx.</span>—Trunk much elevated and compressed, with
+the trunk of the tail very short. Body covered with a silvery
+pigment, without regular scales; series of phosphorescent spots
+run along the lower side of the head, body, and tail. Cleft
+of the mouth wide, vertical, with the lower jaw prominent.
+Jaws armed with small teeth. Eyes rather large, and although
+lateral, directed upwards and placed close together. Ventral
+fins very small. A series of imbricate scutes runs along the
+abdomen, forming a kind of serrature. The dorsal fin is short,
+and occupies about the middle of the length of the fish; it
+is preceded by the first commencement of the formation of a
+spinous dorsal, several neural spines being prolonged beyond the
+dorsal muscle forming a triangular osseous plate. Adipose fin
+rudimentary; anal short; caudal forked.</p>
+</div>
+
+<p><span class="pagenum" id="Page_628">[628]</span></p>
+
+<p>These small fishes are now and then picked up in the Mediterranean and
+Atlantic. According to the dredging-records of the “Challenger,” they
+and the allied genera <i>Argyropelecus</i> and <i>Polyipnus</i> would
+descend to depths of respectively 1100 and 2500 fathoms; but the form
+of their body and their whole organisation render this statement very
+improbable; they most likely live at a small depth during the daytime,
+coming to the surface at night, like many <i>Scopelus</i>.</p>
+
+<p><i>Coccia</i> and <i>Maurolicus</i> are two other genera allied to the
+preceding.</p>
+
+  <div class="figcenter" id="fig285">
+     <img
+    class="p1"   
+    src="images/fig285.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 285.—Chauliodus sloanii.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chauliodus</span>.—Body elongate, compressed, covered with
+exceedingly thin and deciduous scales; series of luminous
+(phosphorescent) spots run along the lower side of the head,
+body, and tail. Head much compressed and elevated, with the
+bones thin, but ossified, and with the opercular portion very
+narrow, the interoperculum being rudimentary. Cleft of the
+mouth exceedingly wide, the intermaxillary forming one half
+of the upper jaw. Each intermaxillary with four long canine
+teeth; edge of the maxillary finely denticulated; mandible with
+pointed, widely set teeth, the anterior of which are exceedingly
+long; none of the large teeth are received within the mouth.
+Palatine with a single series of small pointed teeth; no teeth
+on the tongue. Eye of moderate size. Pectoral and ventral fins
+well developed. Dorsal fin anteriorly on the trunk, before the
+ventrals; adipose fin small, sometimes fimbriated; anal short,
+rather close to the caudal, which is forked. Gill-opening
+very wide, the outer branchial arch extending forward to
+behind the symphysis of the lower jaw; it has no gill-rakers.
+Branchiostegals numerous.</p>
+</div>
+
+<p><span class="pagenum" id="Page_629">[629]</span></p>
+
+<p>This genus, of which one species only (<i>Ch. sloanii</i>) is known, is
+generally distributed over the great depths of the oceans, and does not
+appear to be scarce; it attains to a length of 12 inches, and must be
+one of the most formidable fishes of prey of the deep-sea.</p>
+
+<p>Allied genera are <i>Gonostoma</i>, <i>Photichthys</i>, and
+<i>Diplophos</i>, all of which have the teeth of much smaller size.</p>
+
+
+<h6 class="smcap">Fourteenth Family—Stomiatidæ.</h6>
+
+<p><i>Skin naked, or with exceedingly delicate scales; a hyoid barbel.
+Margin of the upper jaw formed by the intermaxillary and maxillary
+which are both toothed; opercular apparatus but little developed.
+Gill-opening very wide; pseudobranchiæ none. The eggs are enclosed in
+the sacs of the ovarium, and excluded by oviducts.</i></p>
+
+<p>Deep-sea fishes, descending to the greatest depths, characterised by
+their barbel and their formidable dentition.</p>
+
+  <div class="figcenter" id="fig286" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig286.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 286.—<i>Astronesthes niger.</i> The white spots in
+front of the eye are phosphorescent organs.</p>
+  </div>
+
+<p>Some have two dorsal fins, the posterior of which is adipose; they
+belong to the genus <i>Astronesthes</i>, are the smallest of the
+family, and frequently met with in the Atlantic.</p>
+
+<p>The others—viz. <i>Stomias</i>, <i>Echiostoma</i>, <i>Malacosteus</i>,
+and <i>Bathyophis</i>, lack the adipose fin, the rayed dorsal being
+opposite to the anal. Of these the one longest known is</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Stomias.</span>—Body elongate, compressed, covered with
+exceedingly<span class="pagenum" id="Page_630">[630]</span> fine and deciduous scales, which are scarcely
+imbricate, lying in subhexagonal impressions; vent situated at
+no great distance from the caudal fin. Head compressed, with the
+snout very short, and with the cleft of the mouth very wide.
+Teeth pointed, unequal in size, those of the intermaxillaries
+and of the mandible being the longest; maxillary finely
+denticulated; vomer with a pair of fangs; palatine bones and
+tongue with smaller pointed teeth. Eye of moderate size.
+Opercular portion of the head narrow. A fleshy barbel in the
+centre of the hyoid region. Dorsal opposite the anal, close
+to the caudal; pectoral and ventral fins feeble, the latter
+inserted behind the middle of the length of the body. Series of
+phosphorescent dots run along the lower side of the head, body,
+and tail. Gill-opening very wide. Pyloric appendages none.</p>
+</div>
+
+<p>Three species are known; beside specimens which were found floating on
+the surface, others have been dredged from depths varying between 450
+and 1800 fathoms.</p>
+
+
+<h6 class="smcap">Fifteenth Family—Salmonidæ.</h6>
+
+<p><i>Body generally covered with scales; head naked; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally. Belly rounded. A small adipose fin behind
+the dorsal. Pyloric appendages generally numerous, rarely absent.
+Air-bladder large, simple; pseudobranchiæ present. The ova fall into
+the cavity of the abdomen before exclusion.</i></p>
+
+<p>Inhabitants of the sea and freshwater; the majority of the marine
+genera are deep-sea forms. The freshwater forms are peculiar to the
+temperate and arctic zones of the Northern Hemisphere, one occurring
+in New Zealand; many freshwater species periodically or occasionally
+descending to the sea. One of the most valuable families of the class
+of fishes. No fossils of the freshwater forms are known; but of the
+marine genera, <i>Osmerus</i> occurs in the greensand of Ibbenbusen,
+and in the schists of Glaris and Licata; a species of<span class="pagenum" id="Page_631">[631]</span> <i>Mallotus</i>,
+indistinguishable from the living <i>M. villosus</i>, occurs abundantly
+in nodules of clay of unknown geological age in Greenland. Other
+genera, as <i>Osmeroides</i>, <i>Acrognathus</i>, and <i>Aulolepis</i>,
+from the chalk of Lewes, belong to the same fauna as species of Beryx,
+and were probably deep-sea Salmonoids.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Salmo.</span>—Body covered with small scales. Cleft of the
+mouth wide, the maxillary extending to below or beyond the eye.
+Dentition well developed; conical teeth in the jaw bones, on the
+vomer and palatines, and on the tongue, none on the pterygoid
+bones. Anal short, with less than fourteen rays. Pyloric
+appendages numerous; ova large. Young specimens with dark
+cross-bands (Parr-marks).</p>
+</div>
+
+<p>We know of no other group of fishes which offers so many difficulties
+to the ichthyologist with regard to the distinction of the species
+as well as to certain points in their life-history, as this genus,
+although this may be partly due to the unusual attention which has been
+given to their study, and which has revealed an almost greater amount
+of unexplained facts than of satisfactory solutions of the questions
+raised. The almost infinite variations of these fishes are dependent on
+age, sex and sexual development, food, and the properties of the water.
+Some of the species interbreed, and the hybrids mix again with one of
+the parent species, thus producing an offspring more or less similar
+to the pure breed. The <i>coloration</i> is, first of all, subject
+to variation; and consequently this character but rarely assists in
+distinguishing a species, there being not one which would show in all
+stages of development the same kind of coloration. The young of all
+the species are <i>barred</i>; and this is so constantly the case
+that it may be used as a generic or even as a family character, not
+being peculiar to <i>Salmo</i> alone, but also to <i>Thymallus</i>
+and probably to <i>Coregonus</i>. The number of bars is not quite
+constant, but the migratory Trout have two (and even three) more
+than the River-Trout. In some waters River-trout<span class="pagenum" id="Page_632">[632]</span> remain small, and
+frequently retain the Parr-marks all their lifetime; at certain seasons
+a new coat of scales overlays the Parr-marks, rendering them invisible
+for a time; but they reappear in time, or are distinct as soon as the
+scales are removed. When the Salmones have passed this “Parr” state,
+the coloration becomes much diversified. The males, especially during
+and immediately after the spawning time, are more intensely coloured
+and variegated than the females; specimens which have not attained to
+maturity retaining a brighter silvery colour, and being more similar to
+the female fish. Food appears to have less influence on the coloration
+of the outer parts than on that of the flesh; thus the more variegated
+specimens are frequently out of condition, whilst well-fed individuals
+with pinkish flesh are of a more uniform though bright coloration.
+Chemistry has not supplied us yet with an analysis of the substance
+which gives the pink colour to the flesh of many Salmonoids; but
+there is little doubt that it is identical with, and produced by, the
+red pigments of many salt- and freshwater Crustaceans, which form a
+favourite food of these fishes. The water has a marked influence on
+the colours; Trout with intense ocellated spots are generally found in
+clear rapid rivers, and in small open Alpine pools; in the large lakes
+with pebbly bottom the fish are bright silvery, and the ocellated spots
+are mixed with or replaced by X-shaped black spots; in pools or parts
+of lakes with muddy or peaty bottom, the trout are of a darker colour
+generally, and when enclosed in caves or holes, they may assume an
+almost uniform blackish coloration.</p>
+
+<p>The change of scales (that is, the rapid reproduction of the worn
+part of the scales) coincides in the migratory species with their
+sojourn in the sea. The renovated scales give them a bright silvery
+appearance, most of the spots disappearing or being overlaid and hidden
+by the silvery scales. Now, some of the species, like <i>S. fario</i>,
+inhabit all the different<span class="pagenum" id="Page_633">[633]</span> waters indicated, even brackish water, and,
+in consequence, we find a great variation of colour in one and the
+same species; others are more restricted in their habitat, like <i>S.
+salar</i>, <i>S. ferox</i>, etc., and, therefore, their coloration may
+be more precisely defined.</p>
+
+<p>With regard to <i>size</i> the various species do not present an
+equal amount of variation. Size appears to depend on the abundance of
+food and the extent of the water. Thus, the Salmon and the different
+kinds of great Lake-trout do not appear to vary considerably in size,
+because they find the same conditions in all the localities inhabited
+by them. A widely spread species, however, like <i>S. fario</i>, when
+it inhabits a small mountain pool with scanty food, may never exceed a
+weight of eight ounces, whilst in a large lake or river, where it finds
+an abundance and variety of food, it attains to a weight of fourteen
+or sixteen pounds. Such large River-trout are frequently named and
+described as Salmon-trout, Bull-trout, etc. Further, in Salmones, as
+in the majority of fishes and tailed Batrachians, there is an innate
+diversity of growth in individuals hatched from the same spawn. Some
+grow rapidly and normally, others more slowly, and some remain dwarfed
+and stationary at a certain stage of development.</p>
+
+<p>The <i>proportions of the various parts of the body</i> to one another
+vary exceedingly in one and the same species. Beside the usual changes
+from the young to the sexually mature form observed in all fishes,
+the snout undergoes an extraordinary amount of alteration of shape.
+In the mature male the intermaxillaries and the mandible are produced
+in various degrees, and the latter is frequently more or less bent
+upwards. Hence the males have the snout much more pointed and produced,
+and the entire head longer, than the females; with the intermaxillary
+bone the teeth, with which it is armed, are also enlarged, sometimes to
+four times the size of those of the females. And if this development of
+the<span class="pagenum" id="Page_634">[634]</span> front part of the head happens to be going on while the individual
+is able to obtain only a scanty supply of food, the usual proportions
+of the head and trunk are so altered that the species is very difficult
+to recognise. Barren male fish approach the females in the proportions
+of the head and body, but hybrid fishes do not differ in this respect
+from their parents. The abundance or scarcity of food, and the
+disposition or indisposition of the Salmonoids to feed, are other
+causes affecting the growth or fulness of the various parts of the
+body. In well-fed fishes the head is proportionally not only smaller
+but also shorter, and <i>vice versa</i>.</p>
+
+<p>The <i>fins</i> vary to a certain degree. The variation in the
+number of the rays is inconsiderable and of no value for specific
+distinction. The caudal fin undergoes considerable changes of form
+with age, and dependency upon the sexual development. Young specimens
+of all species have this fin more or less deeply excised, so that the
+young of a species which has the caudal emarginate throughout life,
+is distinguished by a deeper incision of the fin, from the young of a
+species which has it truncate in the adult state. As the individuals of
+a species do not all attain to maturity at the same age and at the same
+size, and as mature individuals generally have the caudal less deeply
+excised than immature ones of the same age and size, it is evident that
+the variations in the form of the caudal are considerable and numerous,
+and that it is a very misleading character if due regard be not paid to
+the age and sexual development of the fish. Further, species inhabiting
+rapid streams as well as still waters show considerable variations in
+the form and length of all the fins; those individuals which live in
+rapid streams, being in almost constant motion and wearing off the
+delicate extremities of the fins, have the fin-rays comparatively
+shorter and stouter, and the fins of a more rounded form, particularly
+at the corners, than individuals inhabiting ponds or lakes. Moreover,<span class="pagenum" id="Page_635">[635]</span>
+one and the same individual may pass a part of its life in a lake, and
+enter a river at certain periods, thus changing the form of its fins
+almost periodically.</p>
+
+<p>Finally, to complete our enumeration of these variable characters, we
+must mention that in old males, during and after the spawning-season,
+the <i>skin</i> on the back becomes thickened and spongy, so that the
+scales are quite invisible, being imbedded in the skin.</p>
+
+<hr class="tb">
+
+<p>After this cursory review of variable characters we pass on to those
+which are more constant, not subject to ready modification by external
+circumstances; and which, therefore, ought to be noticed in every
+description of a species of Salmo.</p>
+
+<p>1. <i>The form of the præoperculum of the adult fish.</i> The
+præoperculum is composed of a vertical (posterior) and horizontal
+(lower) part (limb), both meeting at a more or less rounded angle. The
+development of the lower limb is a very constant character; in some
+species (as in the Salmon) it is long, in others (<i>S. ferox</i>,
+<i>S. brachypoma</i>) exceedingly short. The adjoining woodcuts will
+readily show this difference.</p>
+
+  <div class="figcenter" id="fig287" style="max-width: 235px">
+     <img
+    class="p1"   
+    src="images/fig287.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 287.—Præoperculum of A. Salmo salar; B. Salmo
+brachypoma.</p>
+  </div>
+
+<p>In young specimens of all Salmonoids the præoperculum has a very short
+lower limb; but whilst in some species it lengthens with age, its
+development in a horizontal direction is arrested in others.</p>
+
+<p><span class="pagenum" id="Page_636">[636]</span></p>
+
+<p>2. <i>The width and strength of the maxillary of the adult
+fish.</i>—To show this character in two distinct species, we have
+given woodcuts of the maxillaries of females (12 inches long) of <i>S.
+fario</i> and <i>S. levenensis</i> of the same size.</p>
+
+  <div class="figcenter" id="fig288" style="max-width: 480px">
+     <img
+    class="p1"   
+    src="images/fig288.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 288.—Maxillary of A. Salmo fario; B. Salmo
+levenensis.</p>
+  </div>
+
+<p>In young specimens of all Salmonoids the maxillary is comparatively
+shorter and broader, somewhat resembling that of <i>Coregonus</i>; yet
+this bone offers a valuable character for the determination of the
+young of some species; for instance, in a young <i>S. cambricus</i>
+it extends scarcely to below the centre of the eye, whilst in <i>S.
+fario</i> of the same size it reaches to, or even beyond, this point.</p>
+
+  <div class="figcenter" id="fig289" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig289.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 289.—Vomerine teeth of Salmo salar (Salmon). A.
+Side view. B. Lower view.</p>
+  </div>
+
+<p>3. <i>The size of the teeth, those of the intermaxillaries excepted.</i></p>
+
+<p>4. <i>The arrangement, and the permanence or deciduousness of the
+vomerine teeth.</i>—In some species the vomer is normally armed with
+a double or single series throughout life, although, of course, some
+of the teeth are frequently accidentally lost; in others, these teeth
+disappear gradually with age, the hinder ones first, so that finally
+the anterior only remain. In order to ascertain the arrangement of
+the teeth, it is necessary to remove the gengiva. Frequently the
+teeth stand in a distinctly double or single series, or they are
+placed alternately; but frequent irregularities occur which render<span class="pagenum" id="Page_637">[637]</span>
+the character vague, or even unsafe, so that some zoologists have
+rejected it entirely as unreliable. However, when a greater number of
+individuals really belonging to the same species are examined, a pretty
+safe conclusion may be arrived at as regards the arrangement of the
+teeth.</p>
+
+  <div class="figcenter" id="fig290" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig290.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 290.—Vomerine teeth of Salmo fario, lower view.</p>
+  </div>
+
+  <div class="figcenter" id="fig291" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig291.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 291.—Vomerine teeth of a Charr, side view.</p>
+  </div>
+
+<p>5. <i>The form of the caudal fin</i> in specimens of a given size, age,
+and sexual development.</p>
+
+<p>6. <i>A great development of the pectoral fins</i>, when constant in
+individuals from the same locality.</p>
+
+<p>7. <i>The size of the scales</i>, as indicated by the number of
+transverse rows above the lateral line: one of the most constant
+characters.</p>
+
+<p>8. <i>The number of vertebræ.</i>—Considering the great number of
+vertebræ in Salmonoids the constancy of this character is truly
+surprising. An excess or a diminution of the normal number by two, is
+of rare occurrence, and generally to be explained by the fact that
+one vertebra has been abnormally divided into two, two such vertebræ
+being considerably smaller than the others; or, on the other hand,
+that two have merged into one centrum, which is then unusually large,
+and provided with two neural spines. We have seen one case only, in
+which three vertebræ were united. The number of vertebræ can be easily
+ascertained in specimens destined for preservation in spirits, by an
+incision made along one side of the fish, a little above the lateral
+line.</p>
+
+<p>9. <i>The number of pyloric appendages.</i>—There can be no doubt that
+this character may materially assist in fixing a species. We shall see
+that in some species it varies from 30 to 50; but in others, as in the
+Salmon and Charr, it has been<span class="pagenum" id="Page_638">[638]</span> found very constant (see Fig. <a href="#fig56">56</a>, p.
+131). If unexpected variations occur, their cause may be found in a
+partial confluence of the cæca, as we have observed that specimens of
+<i>S. levenensis</i> (a species normally with from 70 to 90 cæca), had
+those appendages of unusual width when the normal number was diminished.</p>
+
+<hr class="tb">
+
+<p>We have mentioned above that many points in the <i>life-history</i> of
+the Salmonoids still remain very obscure:—</p>
+
+<p>1. Johnson, a correspondent of Willughby (“Hist. Pisc.,” p. 194), had
+already expressed his belief that the different Salmonoids interbreed;
+and this view has since been shared by many who have observed these
+fishes in nature. Hybrids between the Sewin (<i>S. cambricus</i>) and
+the River Trout (<i>S. fario</i>) were numerous in the Rhymney and
+other rivers of South Wales, before Salmonoids were almost exterminated
+by the pollutions allowed to pass into those streams, and so variable
+in their characters that the passage from one species to the other
+could be demonstrated in an almost unbroken series, which might induce
+some naturalists to regard both species as identical. Abundant evidence
+of a similar character has accumulated, showing the frequent occurrence
+of hybrids between <i>S. fario</i> and <i>S. trutta</i>; hybrids
+between <i>S. fario</i> and species of Charr have been abundantly bred
+by continental pisciculturists. In some rivers the conditions appear
+to be more favourable to hybridism than in others, in which hybrids
+are of comparatively rare occurrence. Hybrids between the Salmon and
+some other species are very scarce everywhere. The hybrids are sexually
+as much developed as the pure breed, but nothing whatever is known of
+their further propagation and progeny.</p>
+
+<p>2. Siebold has shown that some individuals of every species are not
+sexually developed, and that such individuals differ also externally
+from those normally developed. However,<span class="pagenum" id="Page_639">[639]</span> he appears to have gone too
+far when he stated that this state of sterility extends over the whole
+existence of such individuals, and that, therefore, the external
+peculiarities also remain permanent throughout life. According to
+Widegren this sterility is merely a temporary immaturity, and a part of
+the individuals arrive at a full sexual development at a later or much
+later period than others. To this we may add that many Salmonoids cease
+to propagate their species after a certain age, and that all so called
+overgrown individuals (that is, specimens much exceeding the usual size
+of the species) are barren. Externally they retain the normal specific
+characters.</p>
+
+<p>The Salmon offers a most remarkable instance of irregularity as
+regards the age at which the individuals arrive at maturity. Shaw
+has demonstrated, in the most conclusive manner, that those small
+Salmonoids, which are generally called Parr, are the offspring of the
+Salmon, and that many males, from 7 to 8 inches long, have their sexual
+organs fully developed, and that their milt has all the impregnating
+properties of the seminal fluid of a much older and larger fish. That
+this Parr is not a distinct species—as has been again maintained by
+Couch—is further proved by the circumstance that these sexually mature
+Parr are absolutely identical in their zoological characters with the
+immature Parr, which are undoubtedly young Salmon, and that no Parr
+has ever been found with mature ova. But whether these Parr produce
+normal Salmon, impregnating the ova of female salmon, or mingle with
+the River-trout, or whether they continue to grow and propagate their
+species as fully developed Salmon, are questions which remain to be
+answered. We may only add that, as far as we know, barren old Salmon
+are extremely scarce.</p>
+
+<p>3. The question whether any of the migratory species can be retained
+by artificial means in fresh water, and finally accommodate themselves
+to a permanent sojourn therein,<span class="pagenum" id="Page_640">[640]</span> must be negatived for the present.
+Several instances of successful experiments made for this purpose
+have been brought forward; but all these accounts are open to serious
+doubts, inasmuch as they do not afford us sufficient proof that
+the young fish introduced into ponds were really young migratory
+Salmonoids, or that the full-grown specimens were identical with those
+introduced, and not hybrids or non-migratory Trout of a somewhat
+altered appearance in consequence of the change of their locality.
+We have seen the experiment tried at two places in South Wales, and
+in both cases the Salmon and the pure Sewin died when not allowed to
+return to the sea. On the other hand, hybrid fishes from the Sewin and
+the Trout survived the experiment, and continued to grow in a pond
+perfectly shut up from communication with the sea. In that locality
+neither those hybrids nor the trout spawn.</p>
+
+<p>4. Although the majority of the mature individuals of a migratory
+species ascend a river at a certain fixed time before the commencement
+of spawning, others enter the freshwater at a much earlier period,
+either singly or in small troops; and many appear to return to the sea
+before they reascend at the time of the regular immigration. It is
+not improbable that one and the same individual may change the salt-
+or freshwater several times in the year. However, this is the case in
+certain rivers only, for instance, in those falling into the Moray
+Firth; in others one immigration only is known to occur. The cause of
+the irregular ascents previous to the autumnal ascents is unknown. A
+part, at least, of the hybrid fishes retain the migratory instinct; but
+it is not known whether sterile individuals accompany the others in
+their migrations.</p>
+
+<p>5. It is said that the migratory species invariably return to the river
+in which they are bred. Experiments have shown that this is normally
+the case; but a small proportion<span class="pagenum" id="Page_641">[641]</span> appear to stray so far away from
+their native place as to be unable to find their way back. Almost every
+year Salmon and Sea-trout in the Grilse-state make their appearance at
+the mouth of the Thames (where the migrating Salmonoids have become
+extinct for many years), ready to reascend and to restock this river as
+soon as its poisoned water shall be sufficiently purified to allow them
+a passage.</p>
+
+<p>6. There has been much dispute about the time required for the growth
+of Salmonoids. The numerous and apparently contradictory observations
+tend to show that there is a great amount of variation even among
+individuals of the same origin living under the same circumstances,
+some of them growing much more quickly than others, and being ready to
+descend to the sea twelve months before their brethren. The cause of
+this irregularity is not explained. On the other hand, when we consider
+the fibrous condition of the Salmonoid skeleton, which is much less
+solid, and more wanting in calcareous substance, than that of the
+majority of Teleosteous fishes, we shall be quite prepared to adopt the
+truth of the observation that the young Salmonoids return to the fresh
+water, after a few months sojourn in the sea, and after having feasted
+on nourishing Crustaceans, Sand-eels, etc., with their former weight in
+ounces increased to pounds.</p>
+
+<p>7. Liability to variation in form indicates that an animal can adapt
+itself to a variety of circumstances; therefore, such species as show
+the greatest pliability in this respect, are those which most recommend
+themselves for domestication and acclimatisation within certain
+climatic limits. Thus, the River-trout or Sea-trout were very proper
+subjects for those eminently successful attempts to establish them in
+similar latitudes of the Southern Hemisphere, whilst the attempt of
+transferring them into the low hill-streams of India ended (as could be
+foreseen) in a total failure. Those two species must<span class="pagenum" id="Page_642">[642]</span> now be considered
+to be fully acclimatised in Tasmania and New Zealand, and with but
+little protection may be expected to hold their own in the freshwaters
+of those colonies. Whether the acclimatisation of the Salmon will be
+in the end equally and permanently successful, remains to be seen.
+The true <i>S. salar</i> is not subject to variation, and is very
+sensitive to any change of external conditions, and to every kind of
+interference with its economy. The fourth species, with which attempts
+of acclimatisation in Southern Australia have been made, is a migratory
+Salmon from the Sacramento river in California. This experiment is
+still in progress, and believed to be promising of success. It will be
+a most curious problem to ascertain, how much the original characters
+and habits of those species will be affected by their transference to
+so distant a part of the globe. At present it would be too hazardous
+to offer an opinion on this point, especially as it is a fact that
+numerous cross-breeds have been introduced into, and reared in,
+Tasmania, which must more or less interfere with the characters of the
+pure breeds.</p>
+
+<p>It is apparent, from the foregoing remarks, that the distinction
+of the various species of Salmonidæ is a matter of considerable
+difficulty, and that there is scope for great diversity of opinion.
+At any rate it is only by a close, long-continued study, and constant
+comparison of specimens of various ages and from various localities,
+that one is enabled to find a guide through the labyrinth of confusing
+variations. However, it is a significant fact that the very same
+characters by which we are enabled to distinguish European species
+occur again, though in an exaggerated form, in American Salmonoids
+(which everybody will admit to be of distinct species), and therefore
+our faith in them necessarily becomes strengthened. In accordance with
+acknowledged principles in zoology, forms which differ from their
+congeners by a combination of two or more of constant characters, are
+to be<span class="pagenum" id="Page_643">[643]</span> distinguished under distinct specific names. Most likely they
+have been derived, at a not very remote period, from common ancestors,
+but the question of their specific distinctness is no more affected
+by this consideration than the question whether <i>Salmo</i> and
+<i>Coregonus</i> are distinct genera. Whenever the zoologist observes
+two forms distinguished by peculiarities of organisation, such as
+cannot be conceived to be the effects of an external or internal cause,
+disappearing with the disappearance of that cause, and which forms
+have been propagated and are being propagated uniformly through all
+the generations within the limits of our observations, and are yet
+most probably to be propagated during the existence of mankind, he is
+obliged to describe these forms as distinct, and they will commonly be
+called species.</p>
+
+<p>The species of the genus <i>Salmo</i> are inhabitants of the temperate
+and arctic zones of the Northern Hemisphere; the species are most
+abundant in the northern parts of the temperate zone, becoming scarcer
+beyond the Arctic circle, and in the warmer parts towards the south.
+The southernmost points in which Salmones are found, are, on the
+American continent, the rivers falling into the head of the Californian
+Gulf, and in the Old World the mountain rivers of the Atlas and Hindu
+Kush. The Salmones from those localities are migratory Trout in the New
+World, non-migratory and small in the Old. Those species which range
+to the highest latitudes (lat. 82°) belong to the division of Charr, a
+group which generally are more intolerant of a moderate temperature,
+than real Trout. The genus is subdivided into</p>
+
+<div class="blockquot">
+
+<p><i>a. Salmones</i>—Salmon and Trout—with teeth on the body of
+the vomer as well as its head (see Figs. <a href="#fig289">289</a> and <a href="#fig290">290</a>).</p>
+
+<p><i>b. Salvelini</i>—Charr—with teeth on the head of the vomer
+only (see Fig. <a href="#fig291">291</a>).</p>
+</div>
+
+  <div class="figcenter" id="fig292" style="max-width: 256px">
+     <img
+    class="p1"   
+    src="images/fig292.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 292.—Salmo brachypoma.</p>
+  </div>
+
+<p>Of the host of species (the majority of which is unfortunately<span class="pagenum" id="Page_644">[644]</span> very
+insufficiently characterised) we enumerate the following:—<a id="FNanchor_45" href="#Footnote_45" class="fnanchor">[45]</a></p>
+
+
+<p class="center p1"><i>a.</i> <span class="smcap">Salmones.</span></p>
+
+<div class="blockquot">
+
+<p>1. <i>S. salar</i> (Salmon; Lachs or Salm; Saumon) (Fig. <a href="#fig6">6</a>,
+p. 43). The Salmon can generally be readily recognised, but
+there are instances in which the identification of specimens is
+doubtful, and in which the following characters (besides others)
+will be of great assistance. The tail is covered with relatively
+large scales, there being constantly eleven, or sometimes twelve
+in a transverse series running from behind the adipose fin
+forwards to the lateral line, whilst there are from thirteen to
+fifteen in the different kinds of Sea-trout and River-trout. The
+number of pyloric appendages (see Fig. <a href="#fig56">56</a>, p. 131) is great,
+generally between 60 and 70, more rarely falling to 53 or rising
+to 77. The body of the vomer is armed with a single series of
+small teeth, which at an early age are gradually lost from
+behind towards the front, so that half-grown and old individuals
+have only a few (1–4) left. The Salmon inhabits temperate Europe
+southwards to 43° N. lat., and is not found in any of the rivers
+falling into the Mediterranean. In the New World its southern
+boundary is 41° N. lat.</p>
+
+<p>2. <i>S. trutta</i> (Sea-trout, Salmon-trout).<a id="FNanchor_46" href="#Footnote_46" class="fnanchor">[46]</a>—Especially
+numerous in North Britain.</p>
+
+<p>3. <i>S. cambricus</i> (Sewin).—Wales, South of England,
+Ireland, Norway, and Denmark.</p>
+
+<p>4. <i>S. fario</i> (Common River-trout).</p>
+
+<p>5. <i>S. macrostigma</i> (Algeria).</p>
+
+<p>6. <i>S. lemanus</i> (Lake of Geneva).</p>
+
+<p>7. <i>S. brachypoma.</i>—A migratory species from the rivers
+Forth, Tweed, and Ouse.</p>
+
+<p>8. <i>S. gallivensis</i> (Galway Sea-trout).</p>
+
+<p><span class="pagenum" id="Page_645">[645]</span></p>
+
+<p>9. <i>S. orcadensis.</i>—A non-migratory trout from Lough
+Stennis, in the Orkney Islands.</p>
+
+<p>10. <i>S. ferox.</i>—The great Lake-trout of North Britain,
+Wales, and Ireland.</p>
+
+<p>11. <i>S. stomachicus</i> (the Gillaroo of Ireland).</p>
+
+<p>12. <i>S. nigripinnis</i> from mountain-pools of Wales.</p>
+
+<p>13. <i>S. levenensis</i> (Lochleven Trout).</p>
+
+<p>14. <i>S. oxi</i> from the rivers of the Hindu Kush.</p>
+
+<p>15. <i>S. purpuratus</i> from the Pacific coast of Asia and
+North America.</p>
+
+<p>16. <i>S. macrostoma.</i>—Japan.</p>
+
+<p>17. <i>S. namaycush.</i>—The great Lake-trout of North America.</p>
+</div>
+
+
+<p class="center p1"><i>b.</i> <span class="smcap">Salvelini</span>: Charr.</p>
+
+<div class="blockquot">
+
+<p>1. <i>S. umbla.</i>—The “Ombre chevalier” of the Swiss lakes.</p>
+
+<p>2. <i>S. salvelinus.</i>—The “Sælbling” of the Alpine lakes of
+Bavaria and Austria.</p>
+
+<p>3. <i>S. alpinus.</i>—The common Northern Charr, growing to a
+length of four feet, and migratory.</p>
+
+<p>4. <i>S. killinensis.</i>—The Loch Killin Charr,
+Inverness-shire.</p>
+
+<p>5. <i>S. willughbii.</i>—The Loch Windermere Charr.</p>
+
+<p>6. <i>S. perisii.</i>—The “Torgoch” of Wales.</p>
+
+<p>7. <i>S. grayi.</i>—The “Freshwater Herring” of Lough Melvin,
+Ireland.</p>
+
+<p><span class="pagenum" id="Page_646">[646]</span></p>
+
+<p>8. <i>S. colii.</i>—Charr of Loughs Eske and Dan.</p>
+
+<p>9. <i>S. hucho.</i>—The “Huchen” of the Danube, growing to the
+size of the Salmon.</p>
+
+<p>10. <i>S. alipes</i> from lakes in Boothia Felix and Greenland.</p>
+
+<p>11. <i>S. arcturus.</i>—The most northern species from 82° lat.</p>
+
+<p>12. <i>S. fontinalis.</i>—The common “Brook-trout” of the
+United States.</p>
+
+<p>13. <i>S. oquassa.</i>—A lake species from the State of Maine.</p>
+</div>
+
+<p><i>Oncorhynchus</i> differs from <i>Salmo</i> only in the increased
+number of anal rays, which are more than fourteen. All the species
+are migratory, ascending American and Asiatic rivers flowing into the
+Pacific. The Californian Salmon (<i>O. quinnat?</i>) belongs to this
+genus.</p>
+
+<p>Other allied genera are <i>Brachymystax</i> and <i>Luciotrutta</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Plecoglossus.</span>—Body covered with very small scales.
+Cleft of the mouth wide; maxillary long. Dentition feeble;
+intermaxillaries with a few small, conical, pointed teeth; the
+teeth of the maxillaries and mandibles are broad, truncated,
+lamellated and serrated, movable, seated in a fold of the skin.
+The mandibles terminate each in a small knob, and are not
+jointed at the symphysis. The mucous membrane in the interior of
+the mouth—between the terminal halves of the mandibles—forms a
+peculiar organ, being raised into folds, with a pair of pouches
+in front and a single one behind. Tongue very small, with minute
+teeth, its apical part being toothless; palate apparently
+without teeth.</p>
+</div>
+
+<p>A small aberrant form of Freshwater-Salmonoids abundantly found in
+Japan and the Island of Formosa.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Osmerus.</span>—Body covered with scales of moderate size.
+Cleft of the mouth wide; maxillary long, extending to, or
+nearly to, the hind margin of the orbit. Dentition strong;
+intermaxillary and maxillary teeth small, much smaller than
+those of the mandible. Vomer with a transverse series of teeth,
+several of which are large, fang-like; a series of conical teeth
+along the palatine and pterygoid bones. Tongue with very strong
+fang-like teeth anteriorly, and with several longitudinal series
+of smaller ones posteriorly. Pectoral fins moderately developed.
+Pyloric appendages very short, in small number; ova small.</p>
+</div>
+
+<p><span class="pagenum" id="Page_647">[647]</span></p>
+
+<p>The “Smelt” (<i>O. eperlanus</i>) is common on many places of the
+coasts of Northern Europe and America. In the sea it grows to a length
+of eight inches; but, singularly, it frequently migrates from the sea
+into rivers and lakes, where its growth is very much retarded. That
+this habit is one of very old date, is evident from the fact that
+this small freshwater form occurs, and is fully acclimatised in lakes
+which have now no open communication with the sea. And still more
+singularly, this same habit, with the same result, has been observed in
+the Smelt of New Zealand (<i>Retropinna richardsonii</i>). The Smelt
+is considered a delicacy in Europe, as well as in America, where the
+same species occurs. Two other allied genera, <i>Hypomesus</i> and
+<i>Thaleichthys</i>, are found on the Pacific coast of North America,
+the latter being caught in immense numbers, and known by the name
+“Eulachon” and “Oulachan;” it is so fat, that it is equally used as
+food and as candle.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Mallotus.</span>—Body covered with minute scales, which are
+somewhat larger along the lateral line and along each side
+of the belly; in mature males these scales become elongate,
+lanceolate, densely tiled, with free projecting points, forming
+villous bands. Cleft of the mouth wide; maxillary very thin,
+lamelliform, extending to below the middle of the eye. Lower jaw
+the longer, partly received between the maxillaries. Dentition
+very feeble; the teeth forming single series; only the teeth on
+the tongue are somewhat larger and disposed in an elliptical
+patch. Pectoral fins large, horizontal, with broad base. Pyloric
+appendages very short, in small number; ova small.</p>
+</div>
+
+<p>The “Capelin” (<i>M. villosus</i>) is found on the Arctic coasts of
+America and of Kamtschatka. It is caught in immense numbers by the
+natives, who consume it fresh, or dry it for use in the winter. Its
+length does not exceed nine inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Coregonus.</span>—Body covered with scales of moderate size.
+Cleft of the mouth small; maxillary broad, short or of moderate
+length, not extending behind the orbit. Teeth, if present,<span class="pagenum" id="Page_648">[648]</span>
+extremely minute and deciduous. Dorsal fin of moderate length;
+caudal deeply forked. Ova small.</p>
+</div>
+
+  <div class="figcenter" id="fig293">
+     <img
+    class="p1"   
+    src="images/fig293.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 293.—Coregonus oxyrhynchus.</p>
+  </div>
+
+  <div class="figcenter" id="fig294" style="max-width: 288px">
+     <img
+    class="p1"   
+    src="images/fig294.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 294.—Head of Coregonus oxyrhynchus.</p>
+  </div>
+
+<p>The majority of the species, of which more than forty are known, are
+lacustrine species; and comparatively few are subject to periodical
+migrations to the sea, like <i>Salmo</i>. They are confined to the
+northern parts of temperate Europe, Asia, and North America. Their
+distribution is local, but sometimes three and more species are found
+in the same lake. They abound in every lake and river of the northern
+parts of North America, and are known by the name of “White-fish.”<span class="pagenum" id="Page_649">[649]</span>
+They are of vital importance to some tribes of the native population.
+The European <i>C. oxyrhynchus</i> is as much a marine as a freshwater
+species. In the British Islands several small species occur, viz. <i>C.
+clupeoides</i>, the “Gwyniad,” “Schelly,” or “Powen” from the great
+lakes; <i>C. vandesius</i>, the “Vendace” of Lochmaben; and <i>C.
+pollan</i>, the “Pollan” of the Irish lakes. The latter is brought in
+quantities to Belfast market during the season, that is, at the time
+when it rises from the depths of Lough Neagh to deposit its spawn near
+the shore. Thomson says that in September 1834 some 17,000 were taken
+there at three or four draughts of the net. Some of the species of the
+continent of Europe and America attain to a much larger size than the
+British species, viz. to a length of two feet.</p>
+
+  <div class="figcenter" id="fig295" style="max-width: 293px">
+     <img
+    class="p1"   
+    src="images/fig295.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 295.—Coregonus clupeoides.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Thymallus.</span>—Principally distinguished from
+<i>Coregonus</i> by its long many-rayed dorsal fin.</p>
+</div>
+
+<p>“Graylings”—five species, inhabiting clear streams of the north of
+Europe, Asia, and North America. The best known<span class="pagenum" id="Page_650">[650]</span> are the “Poisson bleu”
+of the Canadian voyageurs (<i>Th. signifer</i>), and the European
+Grayling (<i>T. vulgaris</i>).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Salanx.</span>—Body elongate, compressed, naked or covered
+with small, exceedingly fine, deciduous scales. Head elongate
+and much depressed, terminating in a long, flat, pointed snout.
+Eye small. Cleft of the mouth wide; jaws and palatine bones with
+conical teeth, some of the intermaxillaries and mandibles being
+enlarged; no teeth on the vomer; tongue with a single series of
+curved teeth. Dorsal fin placed far behind the ventrals, but in
+front of the anal; anal long; adipose fin small; caudal forked.
+Pseudobranchiæ well developed; air-bladder none. The entire
+alimentary canal straight, without bend; pyloric appendages
+none. Ova small.</p>
+</div>
+
+<p>This small, transparent, or whitish fish <i>(S. chinensis</i>) is well
+known at Canton and other places of the coast of China as “White-bait,”
+and considered a delicacy. It is evidently a fish which lives at a
+considerable depth in the sea, and approaches the coast only at certain
+seasons.</p>
+
+<p>Finally, this family is represented in the deep sea by three genera,
+<i>Argentina</i>, <i>Microstoma</i>, and <i>Bathylagus</i>, of which
+the two former live at moderate depths, and have been known for a long
+time, whilst the last was discovered during the “Challenger” expedition
+in the Atlantic and Antarctic Oceans at depths of 1950 and 2040
+fathoms. As <i>Argentina</i> is sometimes found in the North Atlantic,
+and even near the British coasts, we give its principal characters.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Argentina.</span>—Scales rather large; cleft of the mouth
+small; intermaxillaries and maxillaries very short, not
+extending to below the orbit. Eye large. Jaws without teeth; an
+arched series of minute teeth across the head of the vomer and
+on the fore part of the palatines; tongue armed with a series of
+small curved teeth on each side. Dorsal fin short, in advance
+of the ventrals; caudal deeply forked. Pseudobranchiæ well
+developed. Pyloric appendages in moderate numbers. Ova small.</p>
+</div>
+
+<p>Four species are known, of which <i>A. silus</i> and <i>A.
+hebridica</i><span class="pagenum" id="Page_651">[651]</span> have been found occasionally on the North British, and,
+more frequently, on the Norwegian coast. The other species are from the
+Mediterranean. Attaining to a length of 18 inches.</p>
+
+
+<h6 class="smcap">Sixteenth Family—Percopsidæ.</h6>
+
+<p><i>Body covered with ctenoid scales; head naked. Margin of the upper
+jaw formed by the intermaxillaries only; opercular apparatus complete.
+Barbels none. Gill-openings wide. Adipose fin present.</i></p>
+
+<p>One genus and species only (<i>Percopsis guttatus</i>); interesting as
+having the general characters of Salmonoids, but the mouth and scales
+of a Percoid. Freshwaters of the northern United States.</p>
+
+
+<h6 class="smcap">Seventeenth Family—Haplochitonidæ.</h6>
+
+<p><i>Body naked or scaly (cycloid). Margin of the upper jaw formed
+by the intermaxillary; opercular apparatus complete. Barbels none.
+Gill-opening wide; pseudobranchiæ. Air-bladder simple. Adipose fin
+present. Ovaries laminated; the eggs fall into the cavity of the
+abdomen, there being no oviduct. Pyloric appendages none.</i></p>
+
+  <div class="figcenter" id="fig296" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig296.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 296.—Prototroctes oxyrhynchus, New Zealand.</p>
+  </div>
+
+<p>Freshwater-fishes which represent the Salmonoids in the southern
+hemisphere. Two genera only are known. <i>Haplochiton</i> (Fig. <a href="#fig104">104</a>,
+p. 250) abundant in lakes and the streams<span class="pagenum" id="Page_652">[652]</span> falling into the Straits of
+Magelhæn and in the rivers of Chile and the Falkland Islands. It has
+the general appearance of a Trout, but is naked. <i>Prototroctes</i>,
+with the habit of a <i>Coregonus</i>, scaly, and provided with minute
+teeth; one species (<i>P. maræna</i>) is common in South Australia, the
+other (<i>P. oxyrhynchus</i>) in New Zealand. The settlers in these
+colonies call them Grayling; the Maori name of the second species is
+“Upokororo.”</p>
+
+
+<h6 class="smcap">Eighteenth Family—Gonorhynchidæ.</h6>
+
+<p><i>Head and body entirely covered with spiny scales; mouth with
+barbels. Margin of the upper jaw formed by the intermaxillary, which,
+although short, is continued downwards as a thick lip, situated in
+front of the maxillary. Adipose fin none; the dorsal fin is opposite to
+the ventrals, and short, like the anal. Stomach simple, without blind
+sac; pyloric appendages in small number. Pseudobranchiæ; air-bladder
+absent. Gill-openings narrow.</i></p>
+
+  <div class="figcenter" id="fig297">
+     <img
+    class="p1"   
+    src="images/fig297.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 297.—Gonorhynchus greyi.</p>
+  </div>
+
+  <div class="figcenter" id="fig298" style="max-width: 224px">
+     <img
+    class="p1"   
+    src="images/fig298.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 298.—Scale of Gonorhynchus greyi.</p>
+  </div>
+
+<p>One genus and species only (<i>Gonorhynchus greyi</i>) is known; it
+is a semi-pelagic fish, not very rare off the Cape of Good Hope, and
+in the Australian and Japanese seas. From 12 to 18 inches<span class="pagenum" id="Page_653">[653]</span> long. The
+colonists in New Zealand name it “Sand-eel,” as it frequents bays with
+sandy bottom. It is eaten.</p>
+
+
+<h6 class="smcap">Nineteenth Family—Hyodontidæ.</h6>
+
+<p><i>Body covered with cycloid scales; head naked; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally, the latter being articulated to the end of the
+former. Opercular apparatus complete. Adipose fin none; the dorsal
+fin belongs to the caudal portion of the vertebral column. Stomach
+horseshoe-shaped, without blind sac; intestine short; one pyloric
+appendage. Pseudobranchiæ none; air-bladder simple. Gill-openings wide.
+The ova fall into the abdominal cavity before exclusion.</i></p>
+
+<p>One genus and species only (<i>Hyodon tergisus</i>) is known, generally
+called “Moon-eye.” It is abundant in the western streams and great
+lakes of North America. From 12 to 18 inches long.</p>
+
+
+<h6 class="smcap">Twentieth Family—Pantodontidæ.</h6>
+
+<p><i>Body covered with large cycloid scales; sides of the head osseous.
+Margin of the upper jaw formed by the single intermaxillary mesially,
+and by the maxillaries laterally. The dorsal fin belongs to the caudal
+portion of the vertebral column, is short, opposite and similar to the
+anal. Gill-openings wide; gill-covers consisting of a præoperculum
+and operculum only. Branchiostegals numerous. Pseudobranchiæ none;
+air-bladder simple. Stomach without coecal sac; one pyloric appendage.
+Sexual organs with a duct.</i></p>
+
+<p>A small freshwater-fish (<i>Pantodon buchholzi</i>), singularly alike
+to a Cyprinodont, from the west coast of Africa.</p>
+
+
+<h6 class="smcap">Twenty-first Family—Osteoglossidæ.</h6>
+
+<p><i>Body covered with large hard scales, composed of pieces like<span class="pagenum" id="Page_654">[654]</span>
+mosaic. Head scaleless; its integuments nearly entirely replaced by
+bone; lateral line composed of wide openings of the mucus-duct. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally. The dorsal fin belongs to the caudal portion of
+the vertebral column, is opposite and very similar to the anal fin;
+both approximate to the rounded caudal (with which they are abnormally
+confluent). Gill-openings wide; pseudobranchiæ none; air-bladder simple
+or cellular. Stomach without coecal sac; pyloric appendages two.</i></p>
+
+<p>Large freshwater-fishes of the tropics, whose singular geographical
+distribution has been noticed above (p. 223).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Osteoglossum.</span>—Cleft of the mouth very wide, oblique,
+with the lower jaw prominent. A pair of barbels at the lower
+jaw. Abdomen trenchant. Bands of rasp-like teeth on the vomer,
+palatine and pterygoid bones, on the tongue and hyoid. Pectoral
+fins elongate.</p>
+</div>
+
+<p><i>O. bicirrhosum</i> from Brazil and Guyana, <i>O. formosum</i> from
+Borneo and Sumatra, <i>O. leichardti</i> from Queensland.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Arapaima.</span>—Cleft of the mouth wide, with the lower jaw
+prominent; barbels none. Abdomen rounded. Jaws with an outer
+series of small conical teeth; broad bands of rasp-like teeth
+on the vomer, palatines, pterygoids, sphenoid, os linguale, and
+hyoid. Pectoral fins of moderate length.</p>
+</div>
+
+  <div class="figcenter" id="fig299">
+     <img
+    class="p1"   
+    src="images/fig299.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 299.—Arapaima gigas.</p>
+  </div>
+
+<p>The largest freshwater Teleostean known, exceeding a length of 15 feet
+and a weight of 400 pounds. It is common in the large rivers of Brazil
+and the Guyanas, and esteemed as an article of food. When salted it is
+exported in large quantities from the inland fisheries to the seaports.</p>
+
+<p><span class="pagenum" id="Page_655">[655]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Heterotis.</span>—Cleft of the mouth rather small, with the
+jaws subequal; barbels none. A single series of small teeth in
+the jaws; pterygoids and hyoid with a patch of small conical
+teeth; none on the vomer or palatines.</p>
+</div>
+
+<p>This fish (<i>H. niloticus</i>), which is not uncommon in the Upper
+Nile and the West African rivers, exhibits several anatomical
+peculiarities. The fourth branchial arch supports a spiral accessory
+organ, the function of which is still unexplained. The air-bladder
+is cellular, and the stomach consists of a membranous and a muscular
+portion.</p>
+
+
+<h6 class="smcap">Twenty-Second Family—Clupeidæ.</h6>
+
+<p><i>Body covered with scales; head naked; barbels none. Abdomen
+frequently compressed into a serrated edge. Margin of the upper jaw
+formed by the intermaxillaries mesially, and by the maxillaries
+laterally; maxillaries composed of at least three movable pieces.
+Opercular apparatus complete. Adipose fin none. Dorsal not elongate;
+anal sometimes very long. Stomach with a blind sac; pyloric appendages
+numerous. Gill-apparatus much developed, the gill-openings being
+generally very wide. Pseudobranchiæ generally present. Air-bladder more
+or less simple.</i></p>
+
+<p>The family of “Herrings” is probably unsurpassed by any other in
+the number of individuals, although others comprise a much greater
+variety of species. The Herrings are principally coast-fishes, or,
+at least, do not go far from the shore; none belong to the deep-sea
+fauna; scarcely any have pelagic habits, but many enter or live in
+fresh waters communicating with the sea. They are spread over all
+the temperate and tropical zones. Fossil remains of Herrings are
+numerous, but the pertinence of some of the genera to this family
+is open to serious doubts, as the remains are too fragmentary to
+allow of determining whether they belong to Salmonoids or Clupeoids.
+Therefore, Agassiz comprised both<span class="pagenum" id="Page_656">[656]</span> families in one—<i>Halecidæ</i>.
+Many of the remains belong to recent genera, which are readily
+recognised, as <i>Clupea</i>, <i>Engraulis</i> and <i>Chanos</i>,
+principally from the schists of Glaris and Licata, from Monte
+Bolca and the Lebanon. Others, like <i>Thrissopater</i>, from the
+Gault at Folkestone, <i>Leptosomus</i>, <i>Opisthopteryx</i>,
+<i>Spaniodon</i>, from the chalk and tertiary formations, can be
+readily associated with recent genera. But the majority do not show
+an apparent affinity to the present fauna. Thus, <i>Halec</i> from
+the chalk of Bohemia, <i>Platinx</i> and <i>Coelogaster</i> from
+Monte Bolca, <i>Rhinellus</i> from Monte Bolca and Mount Lebanon,
+<i>Scombroclupea</i>, with finlets behind the anal, from the Lebanon
+and Comen, and <i>Crossognathus</i> from tertiary Swiss formations,
+allied to <i>Megalops</i>, <i>Spathodactylus</i> from the same
+locality, and <i>Chirocentrites</i> from Mount Lebanon, etc. Finally,
+a genus recently discovered in tertiary formations of Northern Italy,
+<i>Hemitrichas</i>, has been classed with the Clupeoids, from which,
+however, it differs by having two short dorsal fins, so that it must
+be considered, without doubt, to be the representative of a distinct
+family.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Engraulis</span> (including <span class="smcap">Cetengraulis</span>).—Scales
+large or of moderate size. Snout more or less conical,
+projecting beyond the lower jaw. Teeth small or rudimentary.
+Intermaxillaries very small, hidden; maxillary long, attached
+to the cheek by a scarcely distensible membrane. Anal fin of
+moderate or great length. Branchiostegals short, from nine to
+fourteen in number.</p>
+</div>
+
+<p>Not less than forty-three different species of “Anchovies” are known
+from temperate and tropical seas. They exhibit marked differences in
+the length of their maxillary bone, which sometimes does not reach
+the gill-opening, whilst in other species it extends far beyond it;
+and in the number of their anal rays, which varies from 20 to 80.
+Some have the upper pectoral ray prolonged into a filament, thus
+leading towards the succeeding genus, <i>Coilia</i>. The majority
+are recognised, besides, by their peculiar structure, by a broad<span class="pagenum" id="Page_657">[657]</span>
+silvery, lateral band, similar to that observed in the Atherines. The
+most celebrated Anchovy is <i>E. encrasicholus</i>, very plentiful
+in the Mediterranean, but rarely wandering northwards. It is the
+species which, preserved in salt, is exported to all parts of the
+world, although similarly lucrative fisheries of Anchovies might be
+established in Tasmania where the same species occurs, in Chile, China,
+Japan, California, at Buenos Ayres, each of which countries possesses
+Anchovies by no means inferior to the Mediterranean species.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Coilia.</span>—Body terminating in a long tapering tail.
+Scales of moderate size. Snout and jaws as in <i>Engraulis</i>.
+Anal fin exceedingly long, confluent with the caudal. The two or
+three upper pectoral rays are much prolonged, and their branches
+form four, six, or seven filaments.</p>
+</div>
+
+  <div class="figcenter" id="fig300">
+     <img
+    class="p1"   
+    src="images/fig300.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 300.—Coilia clupeoides.</p>
+  </div>
+
+<p>Ten species from Indian and Chinese seas.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chatoëssus.</span>—Body compressed; abdomen serrated. Scales
+of moderate size. Snout obtuse, or obtusely conical, more or
+less projecting beyond the cleft of the mouth, which is narrow,
+more or less transverse. Maxillary joined to the ethmoid, its
+upper portion being behind the intermaxillary. Teeth none.
+Anal fin rather long; dorsal opposite to the ventrals, or to
+the space between ventrals and anal. Gill-membranes entirely
+separate; branchial arches forming two angles, one pointing
+forward and the other backwards; the fourth branchial arch with
+an accessory organ; branchiostegals of moderate length, five or
+six in number.</p>
+</div>
+
+<p>Ten species from the coasts, brackish and fresh waters of<span class="pagenum" id="Page_658">[658]</span> Central
+America (one species ranges to New York), Australia, the East Indies,
+and Japan.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Clupea.</span>—Body compressed, with the abdomen serrated,
+the serrature extending forwards to the thorax. Scales of
+moderate or large, rarely of small size. Upper jaw not
+projecting beyond the lower. Cleft of the mouth of moderate
+width. Teeth, if present, rudimentary and deciduous. Anal fin of
+moderate extent, with less than thirty rays; dorsal fin opposite
+to the ventrals. Caudal forked.</p>
+</div>
+
+<p>This genus comprises more than sixty different species, the
+geographical distribution of which coincides with that of the family.
+The majority are of greater or less utility to man, but a few tropical
+species (<i>C. thrissa</i>, <i>C. venenosa</i>, and others) acquire,
+probably from their food, highly poisonous properties, so as to
+endanger the life of persons eating them. The most noteworthy species
+are—</p>
+
+<p>1. <i>C. harengus</i> (the “Herring”).—It is readily recognised by
+having an ovate patch of very small teeth on the vomer. D. 17–20. A.
+16–18. L. lat. 53–59. Vert. 56. Gill-cover smooth, without radiating
+ridges. It inhabits, in incredible numbers, the German Ocean, the
+northern parts of the Atlantic, and the seas north of Asia. The Herring
+of the Atlantic coasts of North America is identical with that of
+Europe. A second species has been supposed to exist on the British
+coast (<i>C. leachii</i>), but it comprises only individuals of a
+smaller size, the produce of an early or late spawn. Also the so-called
+“White-bait” is not a distinct species, but consists chiefly of the fry
+or the young of herrings, and is obtained “in perfection” at localities
+where these small fishes find an abundance of food, as in the estuary
+of the Thames.</p>
+
+<div class="blockquot">
+
+<p>[Separate accounts on the Herring may be found in Cuvier
+and Valenciennes, “Hist. nat. des Poissons,” vol. xx.; J.
+M. Mitchell, “The Herring, its Natural History and National
+Importance,” Edinb. 1864, 8vo; P. Neucrantz, “De Harengo,”
+Lübeck, 1654; J. S. Dodd, “Essay towards a Natural History
+of the Herring,” Lond. 1768, 8vo; Bock, “Versuch einer
+vollstændigen Natur-und Handels-Geschichte des Hærings,”
+Königsberg, 1769, 8vo.]</p>
+</div>
+
+<p><span class="pagenum" id="Page_659">[659]</span></p>
+
+<p>2. <i>C. mirabilis.</i>—The Herring of the North Pacific.</p>
+
+<p>3. <i>C. sprattus.</i>—The “Sprat.” Without vomerine teeth. D. 15–18.
+A. 17–20. L. lat. 47–48. Vert. 47–49. Gill-cover, smooth, without
+radiating ridges. Abundant on the Atlantic coasts of Europe.</p>
+
+<p>4. <i>C. thrissa.</i>—One of the most common West Indian fishes,
+distinguished by the last dorsal ray being prolonged into a filament.
+Hyrtl has discovered a small accessory branchial organ in this species.</p>
+
+<p>5. <i>C. alosa.</i>—The “Shad” or “Allice Shad,” with very fine and
+long gill-rakers, from 60 to 80 on the horizontal part of the outer
+branchial arch, and with one or more black lateral blotches. Coasts of
+Europe, ascending rivers.</p>
+
+<p>6. <i>C. finta.</i>—The “Shad” or “Twaite Shad,” with stout osseous
+gill-rakers, from 21 to 27 on the horizontal part of the outer
+branchial arch, and spotted like the preceding species. Coasts of
+Europe, ascending rivers, and found in abundance in the Nile.</p>
+
+<p>7. <i>C. menhaden.</i>—The “Mossbanker,” common on the Atlantic coasts
+of the United States. The economic value of this fish is surpassed
+in America only by that of the Gadoids, and derived chiefly from its
+use as bait for other fishes, and from the oil extracted from it, the
+annual yield of the latter exceeding that of the whale (from American
+Fisheries). The refuse of the oil factories supplies a material of much
+value for artificial manures.</p>
+
+<div class="blockquot">
+
+<p>[See G. Brown Goode, “The Natural and Economical History of the
+American Menhaden,” in U.S. Commission of Fish and Fisheries,
+Part V., Washington, 1879, 8vo.]</p>
+</div>
+
+<p>8. <i>C. sapidissima.</i>—The American Shad, abundant, and an
+important food-fish on the Atlantic coasts of North America. Spawns in
+fresh water.</p>
+
+<p>9. <i>C. mattowocca.</i>—The “Gaspereau” or “Ale-wife,” common on the
+Atlantic coasts of North America, ascending into<span class="pagenum" id="Page_660">[660]</span> freshwater in early
+spring, and spawning in ponds and lakes.</p>
+
+<p>10. <i>C. pilchardus.</i>—The “Pilchard” or the “Sardine,” equally
+abundant in the British Channel, on the coast of Portugal, and in
+the Mediterranean, and readily recognised by radiating ridges on the
+operculum, descending towards the sub-operculum.</p>
+
+<p>11. <i>C. sagax.</i>—Representing the Pilchard in the Pacific, and
+found in equally large shoals on the coasts of California, Chile, New
+Zealand, and Japan.</p>
+
+<p>12. <i>C. toli.</i>—The subject of a very extensive fishery on the
+coast of Sumatra for the sake of its roes, which are salted and
+exported to China, the dried fish themselves being sent into the
+interior of the island. The fish is called “Trubu” by the Malays,
+about 18 inches long, and it is said that between fourteen and fifteen
+millions are caught annually.</p>
+
+<p>13. <i>C. scombrina.</i>—The “Oil-Sardine” of the eastern coast of the
+Indian Peninsula.</p>
+
+<hr class="tb">
+
+<p>Other, but less important genera of Clupeoids with serrated abdomen,
+are <i>Clupeoides</i>, <i>Pellonula</i>, <i>Clupeichthys</i>,
+<i>Pellona</i>, <i>Pristigaster</i>, and <i>Chirocentrodon</i> (these
+three last with very small or without any ventral fins).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Albula.</span>—Body oblong, moderately compressed; abdomen
+flat. Scales of moderate size, adherent; lateral line
+distinct. Eyes covered with a broad annular adipose membrane.
+Snout pointed, the upper jaw projecting beyond the lower.
+Mouth inferior, of moderate width, with villiform teeth;
+intermaxillary juxtaposed to the upper anterior edge of the
+maxillary. Dorsal fin opposite to the ventrals; anal fin shorter
+than dorsal. Gill-membranes entirely separate, with numerous
+branchiostegals.</p>
+</div>
+
+<p>One species only (<i>A. conorhynchus</i>), ranging over all tropical
+and sub-tropical seas, and very common in many localities<span class="pagenum" id="Page_661">[661]</span> near the
+coasts. It grows to a length of from two to three feet, and is not
+valued as food.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Elops.</span>—Body rather elongate, moderately compressed;
+abdomen flat. Scales small, adherent; lateral line distinct. A
+narrow osseous lamella, attached to the mandibulary symphysis,
+covers the part between the mandibles. Snout pointed; mouth
+wide, anterior; intermaxillary short, maxillary forming the
+lateral part of the mouth. Bands of villiform teeth in the jaws,
+on the vomer, palatine and pterygoid bones, on the tongue, and
+on the base of the skull. Dorsal fin opposite to ventrals; anal
+rather shorter than dorsal. Gill-membranes entirely separate,
+with very numerous branchiostegals.</p>
+</div>
+
+<p>Two species, of which one, <i>E. saurus</i>, is, like the preceding
+fish, spread over all tropical and sub-tropical seas; it exceeds a
+length of three feet, and is not esteemed as food.</p>
+
+  <div class="figcenter" id="fig301">
+     <img
+    class="p1"   
+    src="images/fig301.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 301.—Elops saurus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Megalops.</span>—Body oblong, compressed, abdomen flat.
+Scales large, adherent; lateral line distinct. A narrow osseous
+lamella, attached to the mandibulary symphysis, between the
+mandibles. Snout obtusely conical; mouth anterior, lower jaw
+prominent; intermaxillary short; maxillary forming the lateral
+part of the mouth. Bands of villiform teeth in the jaws, on
+the vomer, palatine and pterygoid bones, on the tongue and on
+the base of the skull. Dorsal fin opposite to, or immediately
+behind, the ventrals; anal rather larger than dorsal.
+Gill-membranes entirely separate, with numerous branchiostegals.
+Pseudobranchiæ none.</p>
+</div>
+
+<p>Two species, one belonging to the Indo-Pacific (<i>M. cyprinoides</i>),
+the other to the Atlantic (<i>M. thrissoides</i>); they are the largest
+fishes of this family, exceeding a length of five<span class="pagenum" id="Page_662">[662]</span> feet, and excellent
+eating. Young specimens enter freely fresh waters.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chanos.</span>—Body oblong, compressed; abdomen flat.
+Scales small, striated, adherent; lateral line distinct. Snout
+depressed; mouth small, anterior, transverse, the lower jaw with
+a small symphysial tubercle. Intermaxillary in juxtaposition
+to the upper anterior edge of maxillary. Teeth none. Dorsal
+fin opposite to the ventrals; anal small, shorter than dorsal;
+caudal deeply forked. Gill-membranes entirely united below, and
+free from the isthmus. Branchiostegals four, long. An accessory
+branchial organ in a cavity behind the gill-cavity proper.
+Air-bladder divided by a constriction into an anterior and
+posterior portion. Mucous membrane of the œsophagus raised in a
+spiral fold. Intestine with many convolutions.</p>
+</div>
+
+<p>Two species from the Indo-Pacific, of which <i>Ch. salmoneus</i> is
+extremely common; it enters fresh waters, and exceeds a length of four
+feet; its flesh is highly esteemed. The accessory branchial organ and
+the skeleton have been described by <i>Müller</i>, “Bau und Grenzen der
+Ganoiden,” p. 75; and by <i>Hyrtl</i>, “Denkschr. Ak. Wiss. Wien.” xxi.
+1883, p. 1.</p>
+
+  <div class="figcenter" id="fig302">
+     <img
+    class="p1"   
+    src="images/fig302.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 302.—Chanos salmoneus.</p>
+  </div>
+
+<hr class="tb">
+
+<p>The remaining genera belonging to this family are <i>Spratelloides</i>,
+<i>Dussumieria</i>, and <i>Etrumeus</i>, which together form a small
+group, distinguished by an anterior and lateral mouth, by the upper jaw
+not overlapping the lower, by a rounded abdomen, and by lacking the
+gular plate of some of the preceding genera.</p>
+
+<p><span class="pagenum" id="Page_663">[663]</span></p>
+
+
+<h6 class="smcap">Twenty-third Family—Bathythrissidæ.</h6>
+
+<p><i>Body oblong, with rounded abdomen, covered with cycloid scales;
+head naked; barbels none. Margin of the upper jaw formed by the
+intermaxillaries mesially, and by the maxillaries laterally. Opercular
+apparatus complete. Adipose fin none; dorsal fin much elongate, many
+rayed; anal fin short. Stomach with a blind sac; pyloric appendages
+numerous. Gill-apparatus well developed; pseudobranchiæ; gill-openings
+wide; an air-bladder. Ova very small; ovaries without duct.</i></p>
+
+<p>One genus and species only (<i>Bathythrissa dorsalis</i>) from deep
+water (350 fathoms) off the coast of Japan. This remarkable fish has
+the appearance of a <i>Coregonus</i>, and attains to a length of two
+feet. Nothing is known of its osteology, but possibly a fossil genus
+from the Gyps of Montmartre; <i>Notæus</i>, which has also a long
+dorsal fin, may prove to belong to the same family.</p>
+
+
+<h6 class="smcap">Twenty-fourth Family—Chirocentridæ.</h6>
+
+<p><i>Body covered with thin, deciduous scales; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by
+the maxillaries laterally, both bones being firmly united, in
+juxtaposition. Opercular apparatus complete. Adipose fin none; the
+dorsal fin belongs to the caudal portion of the vertebral column.
+Stomach with a blind sac; intestine short, the mucous membrane
+forming a spiral fold; pyloric appendages none. Pseudobranchiæ none;
+air-bladder incompletely divided into cells; gill-opening wide.</i></p>
+
+<p>One genus and species only (<i>Chirocentrus dorab</i>) is known,
+which is common in the Indian Ocean, and attains to a length of about
+three feet; it is not esteemed as food. Remains of fishes similar to
+<i>Chirocentrus</i> are found in the marl slates of Padang, in Sumatra.</p>
+
+<p><span class="pagenum" id="Page_664">[664]</span></p>
+
+
+<h6 class="smcap">Twenty-fifth Family—Alepocephalidæ.</h6>
+
+<p><i>Body with or without scales; head naked; barbels none. Margin of the
+upper jaw formed by the intermaxillaries and maxillaries, the former
+being placed along the upper anterior edge of the latter. Opercular
+apparatus complete. Adipose fin none; the dorsal fin belongs to the
+caudal portion of the vertebral column. Stomach curved, without blind
+sac; pyloric appendages in moderate number. Pseudobranchiæ; air-bladder
+absent. Gill-openings very wide.</i></p>
+
+<p>Before the voyage of the “Challenger” one species only of this family
+was known, <i>Alepocephalus rostratus</i>, a rare fish from the
+Mediterranean; now, four genera with seven species are known, and
+there is no doubt that this family is one of the most characteristic,
+and will prove to be one of the most generally distributed
+forms, of the deep-sea. Their vertical range varies between 345
+(<i>Xenodermichthys</i>) and 2150 (<i>Bathytroctes</i>) fathoms. They
+approach the Salmonoids, but lack invariably the adipose fin. Their
+dentition is very feeble; their eye large; bones thin. Coloration black.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Alepocephalus</span> has thin cycloid scales; a mouth of
+moderate width, and no teeth on the maxillary.</p>
+
+<p><span class="smcap">Bathytroctes</span> has cycloid scales, a wide mouth, and
+teeth on the maxillary as well as intermaxillary.</p>
+
+<p><span class="smcap">Platytroctes</span> has small keeled scales and no ventrals.</p>
+
+<p><span class="smcap">Xenodermichthys</span> with fine nodules instead of scales.</p>
+</div>
+
+
+<h6 class="smcap">Twenty-sixth Family—Notopteridæ.</h6>
+
+<p><i>Head and body scaly; barbels none. Margin of the upper jaw formed
+by the intermaxillaries mesially, and by the maxillaries laterally.
+Opercular apparatus incomplete. Tail prolonged, tapering. Adipose fin
+none. Dorsal short, belonging to the caudal portion of the vertebral
+column; anal very long. Stomach without blind sac; two pyloric
+appendages. Pseudo</i><i>branchiae<span class="pagenum" id="Page_665">[665]</span> none; air-bladder present, divided
+in the interior. The ova fall into the cavity of the abdomen before
+exclusion. On each side a parieto-mastoid cavity leading into the
+interior of the skull.</i></p>
+
+<p>One genus only (<i>Notopterus</i>) with five species which inhabit
+fresh waters of the East Indies and West Africa. Well-preserved remains
+of this genus occur in the marl slates of Padang, in Sumatra. Their
+air-bladder is divided into several compartments, and terminates in two
+horns anteriorly and posteriorly, the anterior horns being in direct
+connection with the auditory organ.</p>
+
+
+<h6 class="smcap">Twenty-seventh Family—Halosauridæ.</h6>
+
+<p><i>Body covered with cycloid scales; head scaly; barbels none. Margin
+of the upper jaw formed by the intermaxillaries mesially, and by the
+maxillaries laterally. Opercular apparatus incomplete. Adipose fin
+none. The short dorsal belongs to the abdominal part of the vertebral
+column; anal very long. Stomach with a blind sac; intestine short;
+pyloric appendages in moderate number. Pseudobranchiæ none. Air-bladder
+large, simple; gill-openings wide. Ovaries closed.</i></p>
+
+<p>The only genus belonging to this family was discovered by the Madeiran
+ichthyologist Johnson, in 1863; but since then the naturalists of the
+“Challenger” expedition have added four other species, showing that
+this type is a deep-sea form and widely distributed; the specimens were
+dredged in depths varying from 560 to 2750 fathoms.</p>
+
+
+<h6 class="smcap">Twenty-eighth Family—Hoplopleuridæ.</h6>
+
+<p><i>Body generally with four series of subtriangular scutes, and with
+intermediate scale-like smaller ones. One (?) dorsal only; head long,
+with the jaws produced.</i></p>
+
+<p><span class="pagenum" id="Page_666">[666]</span></p>
+
+<p><i>Extinct</i>; developed in the chalk and extending into tertiary
+formations: <i>Dercetis</i> (with the upper jaw longest),
+<i>Leptotrachelus</i>, <i>Pelargorhynchus</i>, <i>Plinthophorus</i>,
+<i>Saurorhamphus</i> (with the lower jaw longest), <i>Eurypholis</i>;
+<i>Ischyrocephalus</i> (?). The latter genus, from cretaceous
+formations of Westphalia, is said to have two dorsal fins.</p>
+
+
+<h6 class="smcap">Twenty-ninth Family—Gymnotidæ.</h6>
+
+<p><i>Head scaleless; barbels none. Body elongate, eel-shaped. Margin
+of the upper jaw formed in the middle by the intermaxillaries, and
+laterally by the maxillaries. Dorsal fin absent or reduced to an
+adipose strip; caudal generally absent, the tail terminating in a
+point. Anal fin exceedingly long. Ventrals none. Extremity of the
+tapering tail capable of being reproduced. Vent situated at, or at a
+short distance behind, the throat. Humeral arch attached to the skull.
+Ribs well developed. Gill-openings rather narrow. Air-bladder present,
+double. Stomach with a cæcal sac and pyloric appendages. Ovaries with
+oviducts.</i></p>
+
+<p>Eel-like freshwater fishes from Tropical America.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sternarchus.</span>—Tail terminating in a distinct small
+caudal fin. Teeth small. A rudimentary dorsal fin is indicated
+by an adipose band fitting into a groove on the back of the
+tail; it is easily detached, so as to appear as a thong-like
+appendage fixed in front. Branchiostegals four.</p>
+</div>
+
+<p>Eight species, some have the snout compressed and of moderate length,
+like <i>St. Bonapartii</i> from the River Amazons; others have it
+produced into a long tube, as St. oxyrhynchus from the Essequibo.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Rhamphichthys.</span>—Caudal fin none; teeth none; no trace
+of a dorsal fin. No free orbital margin.</p>
+</div>
+
+<p>Six species, of which, again, some have a tubiform snout, whilst in the
+others it is short.</p>
+
+<p><span class="pagenum" id="Page_667">[667]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Sternopygus.</span>—Caudal fin none; no trace of a dorsal
+fin. Both jaws with small villiform teeth; similar teeth on each
+side of the palate. Body scaly.</p>
+</div>
+
+<p>Four species, very common, and growing to a length of 30 inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Carapus.</span>—Caudal fin none; no trace of a dorsal fin. A
+series of conical teeth in each jaw. Anterior nostrils, wide in
+the upper lip. Body scaly.</p>
+</div>
+
+<p>One species (<i>C. fasciatus</i>) extremely common, and found all over
+tropical America, east of the Andes, from 18 to 24 inches long.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gymnotus.</span>—Caudal and dorsal fins absent; anal
+extending to the end of the tail. Scales none. Teeth conical, in
+a single series. Eyes exceedingly small.</p>
+</div>
+
+<p>The “Electric Eel” is the most powerful of electric fishes, growing to
+a length of six feet, and extremely abundant in certain localities of
+Brazil and the Guyanas. The electric organ consists of two pairs of
+longitudinal bodies, situated immediately below the skin, above the
+muscles; one pair on the back of the tail, and the other pair along
+the anal fin. Each fasciculus is composed of flat partitions or septa,
+with transverse divisions between them. The outer edge of the septa
+appear in nearly parallel lines in the direction of the longitudinal
+axis of the body, and consist of thin membranes, which are easily torn;
+they serve the same purpose as the columns in the analogous organ
+of the Torpedo, making the walls or abutments for the perpendicular
+and transverse dissepiments, which are exceedingly numerous, and so
+closely aggregated as to seem almost in contact. The minute prismatic
+cells, intercepted between these two sorts of plates, contain a
+gelatinous matter; the septa are about one-thirtieth of an inch from
+each other, and one inch in length contains a series of 240 cells,
+giving an enormous surface to the electric organs. The whole apparatus
+is supplied with more than 200 nerves,<span class="pagenum" id="Page_668">[668]</span> which are the continuations of
+the rami anteriores of the spinal nerves. In their course they give out
+branches to the muscles of the back, and to the skin of the animal.
+In the Gymnotus, as in the Torpedo, the nerves supplying the electric
+organs are much larger than those bestowed on any part for the purposes
+of sensation or movement.</p>
+
+<p>The graphic description by Humboldt of the capture of Electric Eels
+by horses driven into the water, which would receive the electric
+discharges and thus exhaust the fishes, seems to rest either on the
+imagination of some person who told it to the great traveller or on
+some isolated incident. Recent travellers have not been able to verify
+it even in the same parts of the country where the practice was said to
+exist.</p>
+
+
+<h6 class="smcap">Thirtieth Family—Symbranchidæ.</h6>
+
+<p><i>Body elongate, naked or covered with minute scales; barbels none.
+Margin of the upper jaw formed by the intermaxillaries only, the well
+developed maxillaries lying behind and parallel to them. Paired fins
+none. Vertical fins rudimentary, reduced to more or less distinct
+cutaneous folds. Vent situated at a, great distance behind the head.
+Ribs present. Gill-openings confluent into one slit situated on the
+ventral surface. Air-bladder none. Stomach without cæcal sac or pyloric
+appendages. Ovaries with oviducts.</i></p>
+
+<p>The fishes of this family consist of freshwater-fishes from tropical
+America and Asia, which, however, enter also brackish water; and of a
+truly marine genus from Australia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Amphipnous.</span>—Vent in the posterior half of the body,
+which is covered with minute scales longitudinally arranged.</p>
+</div>
+
+<p>A common fish (<i>A. cuchia</i>) in Bengal, remarkable for its
+singular respiratory apparatus. It has only three branchial arches,
+with rudimentary branchial laminæ, and with very narrow slits between
+the arches. To supplement this insufficient<span class="pagenum" id="Page_669">[669]</span> respiratory apparatus, a
+lung-like sac is developed on each side of the body behind the head,
+opening between the hyoid and first branchial arch. The interior of the
+sac is abundantly provided with blood-vessels, the arterial coming from
+the branchial arteries, whilst those issuing from it unite to form the
+aorta. <i>A. cuchia</i> approaches the Eels in having the humeral arch
+not attached to the skull.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Monopterus.</span>—Vent in the posterior half of the body,
+which is naked. Three branchial arches with rudimentary gills,
+but without breathing sac.</p>
+</div>
+
+<p>One species (<i>M. javanicus</i>), which is extremely common in the
+East Indian Archipelago and in the eastern parts of the Continent.
+Upwards of three feet long.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Symbranchus.</span>—Vent in the posterior half of the body,
+which is naked. Four branchial arches with well developed gills.</p>
+</div>
+
+<p>Three species, of which one (<i>S. marmoratus</i>) is extremely common
+in tropical America, and the other (<i>S. bengalensis</i>) not less so
+in the East Indies.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Chilobranchus.</span>—Vent in the anterior half of the length
+of the body, which is naked. Vertical fins reduced to a simple
+cutaneous fold, without rays.</p>
+</div>
+
+<p>A small fish (<i>Ch. dorsalis</i>) from North Western Australia and
+Tasmania.</p>
+
+
+<h6 class="smcap">Thirty-First Family—Murænidæ.</h6>
+
+<p><i>Body elongate, cylindrical or “band-shaped, naked or with
+rudimentary scales. Vent situated at a great distance from the head.
+Ventral fins none. Vertical fins, if present, confluent, or separated
+by the projecting tip of the tail. Sides of the upper jaw formed by the
+tooth-bearing maxillaries, the fore part by the intermaxillary, which
+is more or less coalescent with the vomer and ethmoid. Humeral arch not
+attached to the skull. Stomach with a blind sac; no pyloric appendages.
+Organs of reproduction without efferent ducts.</i></p>
+
+<p><span class="pagenum" id="Page_670">[670]</span></p>
+
+<p>The “Eels” are spread over almost all fresh waters and seas of the
+temperate and tropical zones; some descend to the greatest depths
+of the oceans. The young of some have a limited pelagic existence.
+(<i>Leptocephali</i>, see p. 179.) At Monte Bolca fossil remains
+are very numerous, belonging to recent genera, <i>Anguilla</i>,
+<i>Sphagebranchus</i>, and <i>Ophichthys</i>; even larval Leptocephales
+have been preserved. <i>Anguilla</i> has been found also in the chalk
+of Aix and Oeningen.</p>
+
+<p>In the majority of the species the branchial openings in the pharynx
+are wide slits (<i>Murænidæ platyschistæ</i>); in others, the true
+Murænæ, (<i>Murænidæ engyschistæ</i>) they are narrow.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Nemichthys.</span>—Exceedingly elongate, band-shaped; tail
+tapering into a point. Vent approximate to the pectorals,
+but the abdominal cavity extending far behind the vent. Jaws
+produced into a long slender bill, the upper part being formed
+by the vomer and intermaxillaries. The inner surface of the
+bill covered with small tooth-like asperities. Eye large. The
+nostrils of each side are close together, in a hollow before the
+eye. Gill-openings wide, nearly confluent. Pectoral and vertical
+fins well developed.</p>
+</div>
+
+<p>This very singular type is a deep-sea form, occurring at depths of from
+500 to 2500 fathoms. The two species known have hitherto been found in
+the Atlantic only.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Cyema.</span>—This genus combines the form of the snout
+of <i>Nemichthys</i>, with the soft and shorter body of a
+<i>Leptocephalus</i>; but the gill-openings are very narrow
+and close together on the abdominal surface. Vent in about the
+middle of the length of the body; vertical fins well developed,
+confined to, and surrounding, the tail. Pectoral fins well
+developed. Eye very small.</p>
+</div>
+
+<p>Known from two specimens only, 4½ inches long, dredged in depths of
+1500 and 1800 fathoms in the Pacific and Antarctic Oceans.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Saccopharynx.</span>—Deep-sea Congers, with the muscular
+system very feebly developed, with the bones very thin, soft,
+and<span class="pagenum" id="Page_671">[671]</span> wanting in inorganic matter. Head and gape enormous. Snout
+very short, pointed, flexible, like an appendage overlapping
+the gape. Maxillary and mandibulary bones very thin, slender,
+arched, armed with one or two series of long, slender, curved,
+widely set teeth, their points being directed inwards; palate
+toothless. Gill-openings wide, at some distance from the head,
+at the lower part of the sides; gills very narrow, free, and
+exposed. Trunk of moderate length. Stomach distensible in
+an extraordinary degree. Vent at the end of the trunk. Tail
+band-like, exceedingly long, tapering in a very fine filament.
+Pectoral small, present. Dorsal and anal fins rudimentary.</p>
+</div>
+
+<p>This is another extraordinary form of Deep-sea Eels; the muscular
+system, except on the head, is very feebly developed; the bones
+are as thin, soft, and wanting in inorganic matter, as in the
+<i>Trachypteridæ</i>. This fish is known from three specimens only,
+which have been found floating on the surface of the North Atlantic,
+with their stomachs much distended, having swallowed some other fish,
+the weight of which many times exceeded that of their destroyer. It
+attains to the length of several feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Synaphobranchus.</span>—Gill-openings ventral, united
+into a longitudinal slit between the pectoral fins, separate
+internally. Pectoral and vertical fins well developed. Nostrils
+lateral, the anterior subtubular, the posterior round, before
+the lower half of the eye. Cleft of the mouth very wide; teeth
+small; body scaly. Stomach very distensible.</p>
+</div>
+
+<p>Deep-sea Congers, with well-developed muscular system, spread over
+all oceans, and occurring in depths of from 345 to 2000 fathoms. Four
+species are known. Probably attaining to the same length as the Conger.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Anguilla.</span>—Small scales imbedded in the skin. Upper jaw
+not projecting beyond the lower. Teeth small, forming bands.
+Gill-openings narrow, at the base of the pectoral fins. The
+dorsal fin commences at a considerable distance from the occiput.</p>
+</div>
+
+<p>Some twenty-five species of “Eels” are known from the freshwaters and
+coasts of the temperate and tropical zones;<span class="pagenum" id="Page_672">[672]</span> none have been found in
+South America or the west coast of North America and West Africa.
+The following are the most noteworthy:—The common European species
+(<i>A. anguilla</i>) is spread over Europe to 64° 30´ lat. N., and all
+round the Mediterranean area, but is not found either in the Danube
+or in the Black and Caspian Seas; it extends across the Atlantic to
+North America. The form of the snout varies much, and some naturalists
+have believed that specimens with a broad and obtuse snout were
+specifically distinct from those with pointed snout. However, every
+degree of breadth of the snout may be observed; and a much safer
+way of recognizing this species, and distinguishing it from other
+European Eels, is the forward position of the dorsal fin; the distance
+between the commencement of the dorsal and anal fins being as long as,
+or somewhat longer than, the head. Eels grow generally to a length
+of about three feet, but the capture of much larger examples is on
+record. Their mode of propagation is still unknown. So much only is
+certain that they do not spawn in fresh water, that many full-grown
+individuals, but not all, descend rivers during the winter months, and
+that some of them at least must spawn in brackish water or in deep
+water in the sea; for in the course of the summer young individuals
+from three to five inches long ascend rivers in incredible numbers,
+overcoming all obstacles, ascending vertical walls or floodgates,
+entering every larger and smaller tributary, and making their way
+even over terra firma to waters shut off from all communication
+with rivers. Such immigrations have been long known by the name of
+“<i>Eel-fairs</i>.” The majority of the Eels which migrate to the sea
+appear to return to fresh water, but not in a body, but irregularly,
+and throughout the warmer part of the year. No naturalist has ever
+observed these fishes in the act of spawning, or found mature ova; and
+the organs of reproduction of individuals caught in fresh water are
+so little developed and so much alike, that<span class="pagenum" id="Page_673">[673]</span> the female organ can be
+distinguished from the male only with the aid of a microscope.</p>
+
+<p>The second species found in Great Britain, on the coasts of Europe
+generally, in China, New Zealand, and the West Indies, is (<i>A.
+latirostris</i>) the “Grig” or “Glut,” which prefers the neighbourhood
+of the sea to distant inland-waters, and in which the dorsal fin begins
+farther backwards, the distance between the commencement of the dorsal
+and anal fins being shorter than the head; its snout seems to be always
+broad. On the American side of the Atlantic other species, beside <i>A.
+anguilla</i> are found in abundance: <i>A. bostoniensis</i>, <i>A.
+texana</i>. The largest Eels occur in lakes of the islands of the
+Indo-Pacific, and they play a conspicuous part in the mythology of the
+South-Sea Islanders and Maories; individuals of from eight to ten feet
+in length have been seen, and referred to several species, as <i>A.
+mauritiana</i>, <i>fidjiensis</i>, <i>obscura</i>, <i>aneitensis</i>,
+etc.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Conger.</span>—Scaleless. Cleft of the mouth wide, extending
+at least to below the middle of the eye. Maxillary and
+mandibulary teeth arranged in series, one of which contains
+teeth of equal size, and so closely set as to form a cutting
+edge. No canine teeth. Vomerine band of teeth short. Pectoral
+and vertical fins well developed, the dorsal commencing behind
+the root of the pectoral. Gill-openings large, approximate to
+the abdomen. The posterior nostril opposite to the upper or
+middle part of the orbit, the anterior in a tube. Eyes well
+developed.</p>
+</div>
+
+<p>The “Congers” are marine Eels; the best known species (<i>C.
+conger</i>) seems to be almost cosmopolitan, and is plentiful all round
+Europe, at St. Helena, in Japan, and Tasmania. It attains to a length
+of eight feet, and thrives and grows rapidly even in confinement,
+which is not the case with the freshwater Eel. Three other species are
+known, of which <i>C. marginatus</i> from the Indian Ocean, is the most
+common. <i>Leptocephalus morrisii</i> is an abnormal larval condition
+of the Conger.</p>
+
+<p><span class="pagenum" id="Page_674">[674]</span></p>
+
+<p>Genera allied to <i>Conger</i> are <i>Poeciloconger</i>,
+<i>Congromurcæna</i>, <i>Uroconger</i>, and <i>Heteroconger</i>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Murænesox.</span>—Scaleless. Snout produced. Jaws with
+several series of small closely set teeth, anteriorly with
+canines; vomer with several long series of teeth, the middle
+of which is formed by large conical or compressed teeth.
+Gill-openings wide, approximate to the abdomen. Pectoral and
+vertical fins well developed, the dorsal beginning above the
+gill-opening. Two pairs of nostrils, the posterior opposite to
+the upper part or middle of the eye.</p>
+</div>
+
+<p>Four species from tropical seas, <i>M. cinereus</i> being very common
+in the Indian Ocean, and attaining to a length of six feet.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Nettastoma.</span>—Scaleless. Snout much produced, depressed.
+Jaws and vomer with bands of card-like teeth, those along
+the median line of the vomer being somewhat the larger.
+Vertical fins well developed; pectorals none. Gill-openings
+of moderate width, open. Nostrils on the upper surface of the
+head, valvular; the anterior near to the end of the snout, the
+posterior above the anterior angle of the eye.</p>
+</div>
+
+<p>This genus lives at some depth, the Japanese species (<i>N.
+parviceps</i>) having been obtained at 345 fathoms. <i>N. melanurum</i>
+from the Mediterranean, seems to inhabit a similar depth.
+<i>Hyoprorus</i> is its Leptocephalid form.</p>
+
+<p>Genera allied to <i>Murcænesox</i> are <i>Saurenchelys</i>,
+<i>Oxyconger</i>, <i>Hoplunnis</i>, and <i>Neoconger</i>; in all these
+the nostrils have a superior or lateral position. In other genera the
+nostrils perforate the upper lip, as in <i>Myrus</i>, <i>Myrophis</i>,
+<i>Paramyrus</i>, <i>Chilorhinus</i>, <i>Murænichthys</i>, and
+<i>Ophichthys</i>, the last genus deserving of particular mention on
+account of its great range and common occurrence.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Ophichthys.</span>—Nostrils labial; extremity of the tail
+free, not surrounded by a fin.</p>
+</div>
+
+<p>More than eighty species are known, many of which are<span class="pagenum" id="Page_675">[675]</span> abundant on the
+coasts of the tropical and sub-tropical zones. They do not attain to
+a large size, but many must be extremely voracious and destructive to
+other fishes, if we draw an inference from the formidable dentition
+with which their jaws and palate is armed. Other species have much
+more feeble, and some even obtuse teeth, better adapted for seizing
+Crustaceans than vigorous and slippery fishes. Some have rudimentary
+pectoral fins or lack them altogether. Many are highly ornamented with
+bands or spots, the coloration being apparently very constant in the
+several species.</p>
+
+  <div class="figcenter" id="fig303" style="max-width: 301px">
+     <img
+    class="p1"   
+    src="images/fig303.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 303.—Ophichthys crocodilinus, from the Indo-Pacific.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Moringua.</span>—Body scaleless, cylindrical, with the
+trunk much longer than the tail. Pectorals none or small;
+vertical fins but little developed, limited to the tail.
+Posterior nostrils in front of the small eye. Cleft of the mouth
+narrow; teeth uniserial. Heart placed far behind the branchiæ.
+Gill-openings rather narrow, inferior.</p>
+</div>
+
+<p>Six species from freshwaters, brackish water, and the coasts of India
+to the Fiji Islands.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Muræna.</span>—Scaleless. Teeth well developed. Gill-openings
+and clefts between the branchial arches narrow. Pectoral fins
+none; dorsal and anal fins well developed. Two nostrils on each
+side of the upper surface of the snout; the posterior a narrow
+round foramen, with or without tube; the anterior in a tube.</p>
+</div>
+
+<p><span class="pagenum" id="Page_676">[676]</span></p>
+
+  <div class="figcenter" id="fig304" style="max-width: 251px">
+     <img
+    class="p1"   
+    src="images/fig304.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 304.—Head of a Muræna.</p>
+  </div>
+
+  <div class="figcenter" id="fig305" style="max-width: 750px">
+     <img
+    class="p1"   
+    src="images/fig305.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 305.—Muræna pavonina, from Southern Seas.</p>
+  </div>
+
+<p>The Murænas are as abundantly represented in the tropical
+and sub-tropical zones, and have nearly the same range, as
+<i>Ophichthys</i>. The number of species known exceeds eighty. The
+majority are armed with formidable pointed teeth, well suited for
+seizing other fish on which they prey. Large specimens thus armed
+readily attack persons in and out of the water; and as some species
+attain a length of some six or eight feet, they are justly feared by
+fishermen. The minority of species have obtuse and molar-like teeth,
+their food consisting chiefly of Crustaceans and other hard-shelled
+animals. Most of the Murænas are beautifully coloured and spotted, some
+in a regular and constant manner, whilst in others the pattern varies
+in a most irregular fashion: they have quite the appearance of snakes.
+The Muræna of the<span class="pagenum" id="Page_677">[677]</span> Ancient Romans is <i>Muræna helena</i>, which is not
+confined to the Mediterranean, but also found in the Indian Ocean and
+on the coast of Australia. Its skin is of a rich brown, beautifully
+marked with large yellowish spots, each of which contains smaller brown
+spots.</p>
+
+  <div class="figcenter" id="fig306" style="max-width: 569px">
+     <img
+    class="p1"   
+    src="images/fig306.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 306.—Muræna picta, from the Indo-Pacific.</p>
+  </div>
+
+<p><i>Gymnomuræna</i> differs from <i>Muræna</i> in having the fins
+reduced to a short rudiment near the end of the tail. Six species are
+known growing to a length of eight feet.</p>
+
+  <div class="figcenter" id="fig307">
+     <img
+    class="p1"   
+    src="images/fig307.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 307.—Gymnomuræna vittata, from Cuba.</p>
+  </div>
+
+<p><i>Myroconger</i> and <i>Enchelycore</i> belong to the same sub-family<span class="pagenum" id="Page_678">[678]</span>
+as <i>Muræna</i>, but the former is provided with pectoral fins, and in
+the latter the posterior nostril is a long slit, and not round as in
+the other genera.</p>
+
+
+<h4>FIFTH ORDER—LOPHOBRANCHII.</h4>
+
+<p><i>The gills are not laminated, but composed of small rounded lobes
+attached to the branchial arches. Gill-cover reduced to a large simple
+plate. Air-bladder simple, without pneumatic duct. A dermal skeleton
+composed of numerous pieces arranged in segments, replaces more or less
+soft integuments. Muscular system not much developed. Snout prolonged.
+Mouth terminal, small, toothless, formed as in Acanthopterygians.</i></p>
+
+  <div class="figcenter" id="fig308">
+     <img
+    class="p1"   
+    src="images/fig308.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 308.—Gills of Hippocampus abdominalis.</p>
+  </div>
+
+
+<h6 class="smcap">First Family—Solenostomidæ.</h6>
+
+<p><i>Gill-openings wide. Two dorsal fins, the rays of the anterior not
+articulated. All the other fins well developed.</i></p>
+
+<p>One living genus only is known, which was preceded in the tertiary
+epoch by <i>Solenorhynchus</i> (Monte Postale).</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Solenostoma.</span>—Snout produced into a long tube. Body
+compressed, with very short tail. All parts covered with
+thin skin, below which there is a dermal skeleton formed by
+large star-like ossifications. The soft dorsal and anal fins
+on elevated bases; caudal fin long. Ventral fins inserted
+opposite to the<span class="pagenum" id="Page_679">[679]</span> anterior dorsal, close together, seven-rayed;
+they are free in the male, but in the female their inner side
+coalesces with the integuments of the body, a large pouch for
+the reception of the eggs being formed thereby. Air-bladder
+and pseudobranchiæ absent. Branchiostegals four, very thin.
+Intestinal tract very simple, with a stomachic dilatation,
+without pyloric appendages. Ova very small.</p>
+</div>
+
+<p>The dermal skeleton of this singular type is formed by star-like
+ossifications, four in each horizontal and vertical series on the side
+of the fore part of the trunk; each consists of four or three radiating
+branches by which it joins the neighbouring bones; on the hind part
+of the trunk and tail the series are diminished to two. The dorsal
+and abdominal profiles in front of the fins are protected by similar
+bones. The vertebral column is composed of eighteen abdominal and
+fifteen caudal vertebræ, the vertebræ gradually decreasing in length
+backwards, so that the shortness of the tail is caused not only by
+the smaller number of vertebræ, but also by their much lesser length.
+Neural and hæmal spines are developed. The pelvis consists of two pairs
+of cartilaginous laminæ, the convex margin of the anterior fitting
+into an angle of a dermal bone which separates the pelvis from the
+well-ossified humeral arch.</p>
+
+<p>The singular provision for the retention and protection of the eggs has
+been described above (p. 162, figs. 73 and 74), and we have only to
+repeat here that it is the female which takes care of the progeny, and
+not the male as in the following family. Two or three small species are
+known from the Indian Ocean; they are beautifully marked, especially
+the male, which also appears to be of smaller size in this genus than
+the female.</p>
+
+
+<h6 class="smcap">Second Family—Syngnathidæ.</h6>
+
+<p><i>Gill-openings reduced to a very small opening near the upper
+posterior angle of the gill-cover. One soft dorsal fin; no<span class="pagenum" id="Page_680">[680]</span> ventrals,
+and, sometimes, one or more of the other fins are also absent.</i></p>
+
+<p>Small marine fishes, which are abundant on such parts of the coasts
+of the tropical and temperate zones as offer by their vegetation
+shelter to these defenceless creatures. They are bad swimmers (the
+dorsal fin being the principal organ of locomotion), and frequently
+and resistlessly carried by currents into the open ocean or to distant
+coasts. All enter brackish water, some fresh water. The strata of Monte
+Bolca and Licata (Sicily) have, yielded evidence of their existence
+in the tertiary epochs; beside species of <i>Siphonostoma</i> and
+<i>Syngnathus</i> (<i>Pseudosyngnathus</i>), remains of an extinct
+genus, <i>Calamostoma</i>, allied to <i>Hippocampus</i>, but with a
+distinct caudal fin, have been found. On their propagation see p. 163,
+Fig. <a href="#fig76">76</a>.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">A. Syngnathina.</span>—The tail is not prehensile, and
+generally provided with a caudal fin.—<i>Pipe-Fishes.</i></p>
+
+<p><span class="smcap">Siphonostoma.</span>—Body with distinct ridges, the upper
+caudal ridge continuous with the lateral line, but not with
+the dorsal ridge of the trunk. Pectoral and caudal fins well
+developed; dorsal fin of moderate length, opposite to the
+vent. Humeral bones movable, not united into a “breast-ring.”
+Males with an egg-pouch on the tail, the eggs being covered by
+cutaneous folds.</p>
+</div>
+
+<p>Two species, of which <i>S. typhle</i> is common on the British, and
+generally distributed on the European coasts.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Syngnathus.</span>—Body with the ridges more or less
+distinct, the dorsal ridge of the trunk not being continuous
+with that of the tail. Pectoral fins well developed; caudal
+present. Dorsal fin opposite or near to the vent. Humeral
+bones firmly united into the breast-ring. Egg-pouch as in
+<i>Siphonostoma</i>.</p>
+</div>
+
+<p>The distribution of this genus nearly coincides with that of the
+family, some fifty species being known. <i>S. acus</i>, the great
+Pipe-fish (see Fig. <a href="#fig75">75</a>, p. 163), is one of the most common European
+fishes, extending across the Atlantic and<span class="pagenum" id="Page_681">[681]</span> southwards to the Cape
+of Good Hope; it attains a length of 18 inches. Another very common
+species, frequently met at sea, and spread over nearly all the tropical
+and sub-tropical seas, is <i>S. pelagicus</i>, agreeably marked with
+alternate brown and silvery cross-bars.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Doryichthys.</span>—Body with the ridges well developed.
+Pectoral and caudal fins present. Dorsal fin long or of moderate
+length, opposite to the vent. Humeral bones firmly united. Males
+with the lower ridges of the abdomen dilated, the dilated parts
+forming a broad groove for the reception of the ova.</p>
+</div>
+
+<p>In these Pipe-fishes the ova are not received in a completely closed
+pouch, but glued on to the surface of the abdomen. Twenty species from
+tropical seas.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Nerophis.</span>—Body smooth, rounded, with scarcely any
+of the ridges distinct. Pectoral fin none, caudal absent or
+rudimentary, the tail tapering into a point. Dorsal fin of
+moderate length, opposite to the vent. The ova are attached to
+the soft integument of the abdomen of the male, and are not
+covered by lateral folds of the skin.</p>
+</div>
+
+<p>Seven species from the European seas and the Atlantic. <i>N.
+æquoreus</i> (Ocean Pipe-fish), <i>N. ophidion</i> (Straight-nosed
+Pipe-fish), and <i>N. lumbriciformis</i> (Little Pipe-fish), are common
+on the British coasts.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Protocampus.</span>—The whole dermal skeleton is covered with
+skin. A broad cutaneous fold runs along the back in front and
+behind the dorsal; a similar fold along the abdomen. Pectoral
+fin none; caudal very small.</p>
+</div>
+
+<p>The single species of this remarkable genus, <i>P. hymenolomus</i>,
+occurs in the Falkland Islands. It may be regarded as an embryonal form
+of <i>Nerophis</i>, the median skin-folds being evidently remains of
+the fringe which surrounds the body of the embryo.</p>
+
+<p>The other genera belonging to this group are, <i>Icthyocampus</i>,
+<i>Nannocampus</i>, <i>Urocampus</i>, <i>Leptoichthys</i>,
+<i>Coelonotus</i>, and <i>Stigmatophora</i>.</p>
+
+<p><span class="pagenum" id="Page_682">[682]</span></p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hippocampina.</span>—The tail is prehensile, and invariably
+without caudal fin.—<i>Sea-horses.</i></p>
+</div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Gastrotokeus.</span>—Body depressed, the lateral line running
+along the margin of the abdomen. Shields smooth. Tail shorter
+than the body. Pectoral fins. No pouch is developed for the ova,
+which are imbedded in the soft integument of the abdomen of the
+male.</p>
+</div>
+
+<p><i>Gastrotokeus biaculeatus</i>, very common in the Indian Ocean to the
+coasts of Australia.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Solenognathus.</span>—Body compressed, deeper than broad.
+Shields hard, rugose, with round or oval interannular plates;
+and without elongate processes. Tail shorter than the body.
+Pectoral fins.</p>
+</div>
+
+<p>Three species, from the Chinese and Australian Seas; they are the
+largest of Lophobranchs, <i>S. hardwickii</i>, attaining to a length of
+nearly two feet.</p>
+
+  <div class="figcenter" id="fig309" style="max-width: 536px">
+     <img
+    class="p1"   
+    src="images/fig309.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 309.—Phyllopteryx eques.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Phyllopteryx.</span>—Body compressed, or as broad as deep.
+Shields smooth, but some or all of them are provided with
+prominent spines or processes on the edges of the body; some
+of the processes with cutaneous filaments. A pair of spines on
+the upper side of the snout and above the orbit. Tail about as
+long as the body. Pectoral fins. The ova are imbedded in soft
+membrane<span class="pagenum" id="Page_683">[683]</span> on the lower side of the tail, without a pouch being
+developed.</p>
+</div>
+
+<p>Three species from the coasts of Australia. The protective resemblances
+with which many Lophobranchs are furnished, attain to the highest
+degree of development in the fishes of this genus. Not only their
+colour closely assimilates that of the particular kind of seaweed which
+they frequent, but the appendages of their spines seem to be merely
+part of the fucus to which they are attached. They attain a length of
+12 inches.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Hippocampus.</span>—Trunk compressed, more or less elevated.
+Shields with more or less prominent tubercles or spines. Occiput
+compressed into a crest, terminating at its supero-posterior
+corner in a prominent knob (coronet). Pectoral fins. The males
+carry the eggs in a sac at the base of the tail, opening near
+the vent.</p>
+</div>
+
+<p>A singular resemblance of the head and fore part of the body to that
+of a horse, has given to these fishes the name of “Sea-horses.”
+They are abundant between and near the tropics, becoming scarcer
+in higher latitudes. Some twenty species are known, some of which
+have a wide geographical range, as they are often carried to
+great distances with floating objects to which they happen to
+be attached.—<i>Acentronura</i> is a genus closely allied to
+<i>Hippocampus</i>.</p>
+
+
+<h4>SIXTH ORDER—PLECTOGNATHI.</h4>
+
+<p><i>Teleosteous fishes with rough scales, or with ossifications of the
+cutis in the form of scutes or spines; skin sometimes entirely naked.
+Skeleton incompletely ossified, with the vertebræ in small number.
+Gills pectinate; a narrow gill-opening in front of the pectoral fins.
+Mouth narrow; the bones of the upper jaw generally firmly united. A
+soft dorsal fin, belonging to the caudal portion of the vertebral
+column, opposite to the anal; sometimes elements of a spinous dorsal
+besides. Ventral fin none, or reduced to spines. Air-bladder without
+pneumatic duct.</i></p>
+
+<p><span class="pagenum" id="Page_684">[684]</span></p>
+
+
+<h6 class="smcap">First Family—Sclerodermi.</h6>
+
+<p><i>Snout somewhat produced; jaws armed with distinct teeth in small
+number. Skin with scutes or rough. The elements of a spinous dorsal and
+ventral fins generally present.</i></p>
+
+<p>Marine fishes of moderate or small size, very common in the tropical
+zone, but scarcer in higher latitudes. They have been found in
+three localities of tertiary strata, viz., at Monte Bolca, where a
+species of <i>Ostracion</i> occurs, and in the Schists of Glaris,
+from which two genera have been described, <i>Acanthoderma</i>
+and <i>Acanthopleurus</i>, closely allied to <i>Balistes</i> and
+<i>Triacanthus</i>. <i>Glyptocephalus</i> from the Isle of Sheppey
+has the skull of a Balistes, but its body is covered with tubercles
+arranged in regular series. The Scleroderms may be divided into three
+very natural groups:—</p>
+
+<div class="blockquot">
+
+<p>A. <span class="smcap">Triacanthina.</span>—The skin is covered with small,
+rough, scale-like scutes. A spinous dorsal fin with from four to
+six spines. A pair of strong, movable ventral spines, joined to
+the pelvic bone.</p>
+</div>
+
+<p>To this group belong the genera <i>Triacanthodes</i>, <i>Hollardia</i>,
+and <i>Triacanthus</i>, represented by five species, of which
+<i>Triacanthus brevirostris</i> from the Indian Ocean is the most
+common.</p>
+
+<div class="blockquot">
+
+<p>B. <span class="smcap">Balistina.</span>—Body compressed, covered with movable
+scutes or rough. Spinous dorsal reduced to one, two, or three
+spines. Ventral fins reduced to a single pelvic prominence, or
+entirely absent.</p>
+</div>
+
+<p>To this group belong the genera <i>Balistes</i>, <i>Monacanthus</i>,
+and <i>Anacanthus</i>, the last genus being distinguished by a barbel
+at the lower jaw.</p>
+
+  <div class="figcenter" id="fig310">
+     <img
+    class="p1"   
+    src="images/fig310.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 310.—Balistes vidua.</p>
+  </div>
+
+<p><i>Balistes</i>, or the “File-fishes” proper, inhabit the tropical
+and sub-tropical seas; shoals of young are not rarely met with in
+mid-ocean. Some thirty species are known, many attaining a length
+exceeding two feet; but the majority are much<span class="pagenum" id="Page_685">[685]</span> smaller, and frequently
+beautifully and symmetrically marked. Both jaws are armed with eight
+strong incisor-like and obliquely truncated teeth, by which these
+fishes are enabled to break off pieces of corals on which they feed,
+or to chisel a hole into the hard shell of Mollusca, in order to
+extract the soft parts. They destroy an immense number of Mollusks,
+thus becoming most injurious to the pearl-fisheries. The first of their
+three dorsal spines is very strong, roughened in front like a file,
+and hollowed out behind to receive the second much smaller spine,
+which, besides, has a projection in front, at its base, fitting into
+a notch of the first. Thus these two spines can only be raised or
+depressed simultaneously, and the first cannot be forced down, unless
+the second has been previously depressed. The latter has been compared
+to a trigger, hence a second name, “Trigger-fish,” has been given to
+these fishes. Some species are armed with a series of short spines or
+tubercles on each side of the tail. Two species (<i>B. maculatus</i>
+and <i>B. capriscus</i>), common in the Atlantic, sometimes wander to
+the British coasts.</p>
+
+<p>The <i>Monacanthus</i> are similarly distributed as the
+<i>Balistes</i>, and still more abundant, some fifty species being
+known. Their dentition is very similar, but they possess one dorsal
+spine only, and their rough scales are so small as to give a<span class="pagenum" id="Page_686">[686]</span> velvety
+appearance to the skin (Figs. <a href="#fig17">17</a> and <a href="#fig18">18</a>, p. 48). Adult males of some of
+the species possess a peculiar armature on each side of the tail, which
+in females is much less developed or entirely absent. This armature may
+consist either in simple spines arranged in rows, or in the development
+of the minute spines of the scales into long stiff bristles, so that
+the patch on each side of the tail looks like a brush.</p>
+
+<div class="blockquot">
+
+<p>C. <span class="smcap">Ostraciontina.</span>—The integuments of the body form
+a hard continuous carapace, consisting of hexagonal scutes
+juxtaposed in mosaic-fashion. A spinous dorsal and ventral fins
+are absent; but sometimes indicated by protuberances.</p>
+</div>
+
+<p>The “Coffer-fishes” (<i>Ostracion</i>) are too well known to require
+a lengthened description. Only the snout, the bases of the fins, and
+the hind part of the tail are covered with soft skin, so as to admit
+of free action of the muscles moving these parts. The mouth is small,
+the maxillary and intermaxillary bones coalescent, each jaw being armed
+with a single series of small slender teeth. The short dorsal fin is
+opposite to the equally short anal. The vertebral column consists of
+fourteen vertebræ only, of which the five last are extremely short,
+the anterior elongate. Ribs none. The carapaces of some species are
+three-ridged, of others four- and five-ridged, of some provided with
+long spines. Twenty-two species from tropical and sub-tropical seas are
+known.</p>
+
+
+<h6 class="smcap">Second Family—Gymnodontes.</h6>
+
+<p><i>Body more or less shortened. The bones of the upper and lower
+jaw are confluent, forming a beak with a trenchant edge, without
+teeth, with or without median suture. A soft dorsal, caudal and anal
+are developed, approximate. No spinous dorsal. Pectoral fins; no
+ventrals.</i></p>
+
+<p>Marine fishes of moderate or small size from tropical and sub-tropical
+seas. A few species live in fresh water. Fossil remains of
+<i>Diodon</i> are not scarce at Monte Bolca and Licata;<span class="pagenum" id="Page_687">[687]</span> a distinct
+genus, <i>Enneodon</i>, has been described from Monte Postale. The
+Gymnodonts may be divided into three groups:</p>
+
+<div class="blockquot">
+
+<p>A. <span class="smcap">Triodontina.</span>—Tail rather long, with a separate
+caudal fin. Abdomen dilatable into a very large, compressed,
+pendent sac, the lower part of which is merely a flap of skin,
+into which the air does not penetrate, the sac being capable
+of being expanded by the very long pelvic bone. The upper jaw
+divided by a median suture, the lower simple.</p>
+</div>
+
+<p>A single genus and species (<i>Triodon bursarius</i>) from the Indian
+Ocean.</p>
+
+<div class="blockquot">
+
+<p>B. <span class="smcap">Tetrodontina.</span>—Tail and caudal fin distinct. Part of
+the œsophagus much distensible, and capable of being filled with
+air. No pelvic bone.</p>
+</div>
+
+<p>“Globe-fishes” have a short, thick, cylindrical body, with well
+developed fins. It is covered with thick scaleless skin, in which,
+however, spines are imbedded of various sizes. The spines are very
+small, and but partially distributed over the body in some species,
+whilst in others they are very large, and occupy equally every part
+of the body. These fishes have the power of inflating their body by
+filling their distensible œsophagus with air, and thus assume a more or
+less globular form. The skin is, then, stretched to its utmost extent,
+and the spines protrude and form a more or less formidable defensive
+armour, as in a hedgehog; therefore they are frequently called
+“Sea-hedgehogs.” A fish thus blown out turns over and floats belly
+upwards, driving before the wind and waves. However, it is probable
+that the spines are a protection not only when the fish is on the
+surface and able to take in air, but also when it is under water. Some
+Diodonts, at any rate, are able to erect the spines about the head by
+means of cutaneous muscles; and, perhaps, all fill their stomach with
+water instead of air, for the same purpose and with the same effect. In
+some Diodonts the spines are fixed, erect, not movable. The Gymnodonts
+generally, when taken,<span class="pagenum" id="Page_688">[688]</span> produce a sound, doubtless by the expulsion
+of air from the œsophagus. Their vertebral column consists of a small
+number of vertebræ, from 20 to 29, and their spinal chord is extremely
+short. All these fishes have a bad reputation, and they are never
+eaten; indeed, some of them are highly poisonous, and have caused long
+continued illness and death. Singularly, the poisonous properties of
+these fishes vary much as regards intensity, only certain individuals
+of a species, or individuals from a certain locality, or caught at a
+certain time of the year, being dangerous. Therefore it is probable
+that they acquire their poisonous quality from their food, which
+consists in corals and hard-shelled Mollusks and Crustaceans. Their
+sharp beaks, with broad masticating posterior surface, are admirably
+adapted for breaking off branchlets of coral-stocks, and for crushing
+hard substances.</p>
+
+  <div class="figcenter" id="fig311" style="max-width: 255px">
+     <img
+    class="p1"   
+    src="images/fig311.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 311.—Jaws of Tetrodon.</p>
+  </div>
+
+  <div class="figcenter" id="fig312">
+     <img
+    class="p1"   
+    src="images/fig312.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 312.—Tetrodon margaritatus.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Tetrodon</span> (including <i>Xenopterus</i>).—Both the upper
+and lower jaws are divided into two by a mesial suture.</p>
+</div>
+
+<p>Extremely numerous in tropical and sub-tropical zones, more than
+sixty species being known. In some of the species the dermal
+spines are extremely small, and may be absent altogether. Many are
+highly ornamented with spots or bands. A few species live in large
+rivers—thus <i>T. psittacus</i> from Brazil; <i>T. fahaka</i>, a fish
+well known to travellers on the Nile, and likewise abundant in West
+African rivers; <i>T. fluvi</i><i>atilis</i><span class="pagenum" id="Page_689">[689]</span> from brackish water and
+rivers of the East Indies. The species figured is one of the smallest,
+about six inches long, and common in the Indo-Pacific.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Diodon.</span>—Jaws without mesial suture, so that there is
+only one undivided dental plate above and one below.</p>
+</div>
+
+<p>In these fishes, as well as in some closely allied genera, the dermal
+spines are much more developed than in the Tetrodonts; in some the
+spines are erectile, as in <i>Diodon</i>, <i>Atopomycterus</i>,
+<i>Trichodiodon</i>, and <i>Trichocyclus</i>; in others they are stiff
+and immovable, as in <i>Chilomycterus</i> and <i>Dicotylichthys</i>.
+Seventeen species are known, of which <i>Diodon hystrix</i> is the most
+common as it is the largest, growing to a length of two feet. It is
+spread over the Tropical Atlantic as well as Indo-Pacific, as is also a
+smaller, but almost equally common species, <i>Diodon maculatus</i>.</p>
+
+  <div class="figcenter" id="fig313">
+     <img
+    class="p1"   
+    src="images/fig313.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 313.—Diodon maculatus.</p>
+  </div>
+
+  <div class="figcenter" id="fig314">
+     <img
+    class="p1"   
+    src="images/fig314.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 314.—Diodon maculatus, inflated.</p>
+  </div>
+
+<p><span class="pagenum" id="Page_690">[690]</span></p>
+
+<div class="blockquot">
+
+<p>C. <span class="smcap">Molina.</span>—Body compressed, very short; tail extremely
+short, truncate. Vertical fins confluent. No pelvic bone.</p>
+</div>
+
+<p>The “Sun-fishes” (<i>Orthagoriscus</i>) are pelagic fishes, found in
+every part of the oceans within the tropical and temperate zones.
+The singular shape of their body and the remarkable changes which
+they undergo with age, have been noticed above (p. 175, Figs. <a href="#fig93">93</a>,
+<a href="#fig97">94</a>). Their jaws are undivided in the middle, comparatively feeble,
+but well adapted for masticating their food, which consists of small
+pelagic Crustaceans. Two species are known. The common Sun-fish,
+<i>O. mola</i>, which attains to a very large size, measuring seven
+or eight feet, and weighing as many hundredweights. It has a rough,
+minutely granulated skin. It frequently approaches the southern coasts
+of England and the coasts of Ireland, and is seen basking in calm
+weather on the surface. The second species, <i>O. truncatus</i>, is
+distinguished by its smooth, tessellated skin, and one of the scarcest
+fishes in collections. The shortness of the vertebral column of the
+Sun-fishes, in which the number of caudal vertebra is reduced to seven,
+the total number being seventeen, and the still more reduced length of
+the spinal chord have been noticed above (p. 96).</p>
+
+<p><span class="pagenum" id="Page_691">[691]</span></p>
+
+
+<h3>THIRD SUB-CLASS—CYCLOSTOMATA.</h3>
+
+<p><i>Skeleton cartilaginous and notochordal, without ribs and without
+real jaws. Skull not separate from the vertebral column. No limbs.
+Gills in the form of fixed sacs, without branchial arches, six or seven
+in number on each side. One nasal aperture only. Heart without bulbus
+arteriosus. Mouth anterior, surrounded by a circular or subcircular
+lip, suctorial. Alimentary canal straight, simple, without coecal
+appendages, pancreas or spleen. Generative outlet peritoneal. Vertical
+fins rayed.</i></p>
+
+<p>The Cyclostomes are most probably a very ancient type. Unfortunately
+the organs of these creatures are too soft to be preserved, with the
+exception of the horny denticles with which the mouth of some of them
+is armed. And, indeed, dental plates, which are very similar to those
+of <i>Myxine</i>, are not uncommon in certain strata of Devonian and
+Silurian age (see p. 193). The fishes belonging to this sub-class may
+be divided into two families—</p>
+
+
+<h6 class="smcap">First Family—Petromyzontidæ.</h6>
+
+<p><i>Body eel-shaped, naked. Subject to a metamorphosis; in the perfect
+stage with a suctorial mouth armed with teeth, simple or multicuspid,
+horny, sitting on a soft papilla. Maxillary, mandibulary, lingual, and
+suctorial teeth may be distinguished. Eyes present (in mature animals).
+External nasal aperture in the middle of the upper side of the head.
+The nasal duct terminates without perforating the palate. Seven
+branchial<span class="pagenum" id="Page_692">[692]</span> sacs and apertures on each side behind the head; the inner
+branchial ducts terminate in a separate common tube. Intestine with a
+spiral valve. Eggs small. The larvæ without teeth, and with a single
+continuous vertical fin.</i></p>
+
+<p>“Lampreys” are found in the rivers and on the coasts of the temperate
+regions of the northern and southern hemispheres. Their habits are but
+incompletely known, but so much is certain that at least some of them
+ascend rivers periodically, for the purpose of spawning, and that the
+young pass several years in rivers, whilst they undergo a metamorphosis
+(see p. 170). They feed on other fishes, to which they suck themselves
+fast, scraping off the flesh with their teeth. Whilst thus engaged they
+are carried about by their victim; Salmon have been captured in the
+middle course of the Rhine with the Marine Lamprey attached to them.</p>
+
+  <div class="figcenter" id="fig315" style="max-width: 268px">
+     <img
+    class="p1"   
+    src="images/fig315.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 315.—Mouth of Larva of Petromyzon branchialis.</p>
+  </div>
+
+  <div class="figcenter" id="fig316" style="max-width: 289px">
+     <img
+    class="p1"   
+    src="images/fig316.jpg"
+     alt="">
+     <p class="p0 p-left hangingindent smaller">Fig. 316.—Mouth of Petromyzon fluviatilis. <i>mx</i>,
+Maxillary tooth; <i>md</i>, Mandibulary tooth; <i>l</i>, Lingual tooth;
+<i>s</i>, Suctorial teeth.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Petromyzon.</span>—Dorsal fins two, the posterior continuous
+with the caudal. The maxillary dentition consists of two teeth
+placed close together, or of a transverse bicuspid ridge;
+lingual teeth serrated.</p>
+</div>
+
+<p>The Lampreys belonging to this genus are found in the northern
+hemisphere only; the British species are the Sea-Lamprey (<i>P.
+marinus</i>), exceeding a length of three feet, and not uncommon on the
+European and North American coasts; the River-Lamprey or Lampern (<i>P.
+fluviatilis</i>), ascending in<span class="pagenum" id="Page_693">[693]</span> large numbers the rivers of Europe,
+North America, and Japan, and scarcely attaining a length of two feet;
+the “Pride” or “Sand-Piper” or Small Lampern (<i>P. branchialis</i>),
+scarcely twelve inches long, the larva of which has been long known
+under the name of <i>Ammocoetes</i>.</p>
+
+<p><i>Ichthyomyzon</i> from the western coasts of North America is said to
+have a tricuspid maxillary tooth.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Mordacia.</span>—Dorsal fins two, the posterior continuous
+with the caudal. The maxillary dentition consists of two
+triangular groups, each with three conical acute cusps; two
+pairs of serrated lingual teeth.</p>
+</div>
+
+  <div class="figcenter" id="fig317" style="max-width: 436px">
+     <img
+    class="p1"   
+    src="images/fig317.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 317.—Mouth of Mordacia mordax, closed and opened.</p>
+  </div>
+
+<p>A Lamprey <i>(M. mordax</i>) from the coasts of Chile and Tasmania.
+This fish seems to be provided sometimes with a gular sac, like the
+following.<a id="FNanchor_47" href="#Footnote_47" class="fnanchor">[47]</a></p>
+
+  <div class="figcenter" id="fig318">
+     <img
+    class="p1"   
+    src="images/fig318.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 318.—Mordacia mordax.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Geotria.</span>—Dorsal fins two, the posterior separate from
+the<span class="pagenum" id="Page_694">[694]</span> caudal. Maxillary lamina with four sharp flat lobes; a pair
+of long pointed lingual teeth.</p>
+</div>
+
+<p>Two species, one from Chile and one from South Australia. They grow
+to a length of two feet, and in some specimens the skin of the throat
+is much expanded, forming a large pouch. Its physiological function
+is not known. The cavity is in the subcutaneous cellular tissue, and
+does not communicate with the buccal or branchial cavities. Probably
+it is developed with age, and absent in young individuals. In all
+the localities in which these Extra-european Lampreys are found,
+<i>Ammocoetes</i> forms occur, so that there is little doubt that they
+undergo a similar metamorphosis as <i>P. branchialis</i>.</p>
+
+
+<h6 class="smcap">Second Family—myxinidæ.</h6>
+
+<p><i>Body eel-shaped, naked. The single nasal aperture is above the
+mouth, quite at the extremity of the head, which is provided with four
+pairs of barbels. Mouth without lips. Nasal duct without cartilaginous
+rings, penetrating the palate. One median tooth on the palate, and
+two comb-like series of teeth on the tongue</i> (see Fig. <a href="#fig101">101</a>).
+<i>Branchial apertures at a great distance from the head; the inner
+branchial ducts lead into the œsophagus. A series of mucous sacs along
+each side of the abdomen. Intestine without spiral valve. Eggs large,
+with a horny case provided with threads for adhesion.</i></p>
+
+  <div class="figcenter" id="fig319" style="max-width: 250px">
+     <img
+    class="p1"   
+    src="images/fig319.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 319.—Ovum of Myxine glutinosa, enlarged.</p>
+  </div>
+
+<p>The fishes of this family are known by the names of “Hag-Fish,”
+“Glutinous Hag,” or “Borer;” they are marine fishes with a similar
+distribution as the Gadidæ, being most plentiful in the higher
+latitudes of the temperate zones of the northern and southern
+hemispheres. They are frequently found buried<span class="pagenum" id="Page_695">[695]</span> in the abdominal cavity
+of other fishes, especially Gadoids, into which they penetrate to feed
+on their flesh. They secrete a thick glutinous slime in incredible
+quantities, and are therefore considered by fishermen a great nuisance,
+seriously damaging the fisheries and interfering with the fishing in
+localities where they abound. <i>Myxine</i> descends to a depth of
+345 fathoms, and is generally met with in the Norwegian Fjords at 70
+fathoms, sometimes in great abundance.</p>
+
+<div class="blockquot">
+
+<p><span class="smcap">Myxine</span>.—One external branchial aperture only on each
+side of the abdomen, leading by six ducts to six branchial sacs.</p>
+</div>
+
+<p>Three species from the North Atlantic, Japan, and Magelhæn’s Straits.</p>
+
+  <div class="figcenter" id="fig320" style="max-width: 650px">
+     <img
+    class="p1"   
+    src="images/fig320.jpg"
+     alt="">
+     <p class="p0 p-left hangingindent smaller">Fig. 320.—Myxine australis. A, Lower aspect of head;
+<i>a</i>, Nasal aperture; <i>b</i>, Mouth; <i>g</i>, Branchial
+aperture; <i>v</i>, Vent.</p>
+  </div>
+
+<div class="blockquot">
+
+<p><span class="smcap">Bdellostoma</span>.—Six or more external branchial apertures
+on each side, each leading by a separate duct to a branchial sac.</p>
+</div>
+
+<p>Two species from the South Pacific.</p>
+
+<p><span class="pagenum" id="Page_696">[696]</span></p>
+
+
+<h3>FOURTH SUB-CLASS—LEPTOCARDII.</h3>
+
+
+<p><i>Skeleton membrano-cartilaginous and notochordal, ribless. No brain.
+Pulsating sinuses in place of a heart. Blood colourless. Respiratory
+cavity confluent with the abdominal cavity; branchial clefts in great
+number, the water being expelled by an opening in front of the vent.
+Jaws none.</i></p>
+
+<p>This sub-class is represented by a single family (<i>Cirrostomi</i>)
+and by a single genus (<i>Branchiostoma</i>);<a id="FNanchor_48" href="#Footnote_48" class="fnanchor">[48]</a> it is the lowest in
+the scale of fishes, and lacks so many characteristics, not only of
+this class, but of the vertebrata generally, that Hæckel, with good
+reason, separates it into a separate class, that of <i>Acrania</i>. The
+various parts of its organisation have been duly noticed in the first
+part of this work.</p>
+
+<p>The “Lancelet” (<i>Branchiostoma lanceolatum</i>, see Fig. <a href="#fig28">28</a>, p. 63),
+seems to be almost cosmopolitan within the temperate and tropical
+zones. Its small size, its transparency, and the rapidity with which it
+is able to bury itself in the sand, are the causes why it escapes so
+readily observation, even at localities where it is known to be common.
+Shallow, sandy parts of the coasts seem to be the places on which it
+may be looked for. It has been found on many localities of the British,
+and generally European coasts, in North America, the West Indies,
+Brazil, Peru, Tasmania, Australia, and Borneo. It rarely exceeds
+a length of three inches. A smaller species, in which the dorsal
+fringe is distinctly higher and rayed, and in which the caudal fringe
+is absent, has been described under the name of <i>Epigionichthys
+pulchellus</i>; it was found in Moreton Bay.</p>
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_697">[697]</span></p>
+
+<h2>APPENDIX.</h2>
+</div>
+
+<p class="center smaller">DIRECTIONS FOR COLLECTING AND PRESERVING FISHES.</p>
+
+
+<p>Whenever practicable fishes ought to be preserved in spirits.</p>
+
+<p>To insure success in preserving specimens the best and strongest
+spirits should be procured, which, if necessary, can be reduced to
+the strength required during the journey with water or weaker spirit.
+Travellers frequently have great difficulties in procuring spirits
+during their journey, and therefore it is advisable, especially during
+sea voyages, that the traveller should take a sufficient quantity
+with him. Pure spirits of wine is best. Methylated spirits may be
+recommended on account of their cheapness; however, specimens do not
+keep equally well in this fluid, and very valuable objects, or such as
+are destined for minute anatomical examination, should always be kept
+in pure spirits of wine. If the collector has exhausted his supply of
+spirits he may use arrack, cognac, or rum, provided that the fluids
+contain a sufficient quantity of alcohol. Generally speaking, spirits
+which, without being previously heated, can be ignited by a match or
+taper, may be used for the purposes of conservation. The best method
+to test the strength of the spirits is the use of a hydrometer. It
+is immersed in the fluid to be measured, and the deeper it sinks the
+stronger is the spirit. On its scale the number 0 signifies what is
+called proof spirit, the lowest degree of strength which can be used
+for the conservation of fish for any length of time. Spirits, in which
+specimens are packed permanently, should be from 40 to 60 above proof.
+If the hydrometers are made of glass they are easily broken, and
+therefore the traveller had better provide himself with three or four
+of them, their cost being very trifling. Further, the collector<span class="pagenum" id="Page_698">[698]</span> will
+find a small distilling apparatus very useful. By its means he is able
+not only to distil weak and deteriorated spirits or any other fluid
+containing alcohol, but also, in case of necessity, to prepare a small
+quantity of drinkable spirits.</p>
+
+<p>Of collecting vessels we mention first those which the collector
+requires for daily use. Most convenient are four-sided boxes made of
+zinc, 18 in. high, 12 in. broad, and 5 in. wide. They have a round
+opening at the top of 4 in. diameter, which can be closed by a strong
+cover of zinc of 5 in. diameter, the cover being screwed into a raised
+rim round the opening. In order to render the cover air-tight, an
+indiarubber ring is fixed below its margin. Each of these zinc boxes
+fits into a wooden case, the lid of which is provided with hinges and
+fastenings, and which on each side has a handle of leather or rope, so
+that the box can be easily shifted from one place to another. These
+boxes are in fact made from the pattern of the ammunition cases used
+in the British army, and extremely convenient, because a pair can be
+easily carried strapped over the shoulders of a man or across the
+back of a mule. The collector requires at least two, still better
+four or six, of these boxes. All those specimens which are received
+during the day are deposited in them, in order to allow them to be
+thoroughly penetrated by the spirit, which must be renewed from time
+to time. They remain there for some time under the supervision of the
+collector, and are left in these boxes until they are hardened and
+fit for final packing. Of course, other more simple vessels can be
+used and substituted for the collecting boxes. For instance, common
+earthenware vessels, closed by a cork or an indiarubber covering,
+provided they have a wide mouth at the top, which can be closed so
+that the spirit does not evaporate, and which permits of the specimens
+being inspected at any moment without trouble. Vessels in which the
+objects are permanently packed for the home journey are zinc boxes of
+various sizes, closely fitting into wooden cases. Too large a size
+should be avoided, because the objects themselves may suffer from the
+superimposed weight, and the risk of injury to the case increases with
+its size. It should hold no more than 18 cubic feet at most, and what,
+in accordance with the size of the specimens, has to be added in length
+should be deducted in depth or breadth.<span class="pagenum" id="Page_699">[699]</span> The most convenient cases,
+but not sufficient for all specimens, are boxes 2 feet in length, 1½
+foot broad, and 1 foot deep. The traveller may provide himself with
+such cases ready made, packing in them other articles which he wants
+during his journey; or he may find it more convenient to take with him
+only the zinc plates cut to the several sizes, and join them into boxes
+when they are actually required. The requisite wooden cases can be
+procured without much difficulty almost everywhere. No collector should
+be without the apparatus and materials for soldering, and he should be
+well acquainted with their use. Also a pair of scissors to cut the zinc
+plates are useful.</p>
+
+<p>Wooden casks are not suitable for the packing of specimens preserved
+in spirits, at least not in tropical climates. They should be used in
+cases of necessity only, or for packing of the largest examples, or for
+objects preserved in salt or brine.</p>
+
+<p>Very small and delicate specimens should never be packed together with
+larger ones, but separately, in small bottles.</p>
+
+<p><i>Mode of preserving.</i>—All fishes, with the exception of very
+large ones (broad kinds exceeding 3–4 feet in length; eel-like kinds
+more than 6 feet long), should be preserved in spirits. A deep cut
+should be made in the abdomen between the pectoral fins, another in
+front of the vent, and one or two more, according to the length of
+the fish, along the middle line of the abdomen. These cuts are made
+partly to remove the fluid and easily decomposing contents of the
+intestinal tract, partly to allow the spirit quickly to penetrate into
+the interior. In large fleshy fishes several deep incisions should
+be made with the scalpel into the thickest parts of the dorsal and
+caudal muscles, to give ready entrance to the spirits. The specimens
+are then placed in one of the provisional boxes, in order to extract,
+by means of the spirit, the water of which fishes contain a large
+quantity. After a few days (in hot climates after 24 or 48 hours) the
+specimens are transferred into a second box with stronger spirits, and
+left therein for several days. A similar third and, in hot climates
+sometimes a fourth, transfer is necessary. This depends entirely on
+the condition of the specimens. If, after ten or fourteen days of
+such treatment the specimens are firm and in good condition, they may
+be left in the spirits last used until they are<span class="pagenum" id="Page_700">[700]</span> finally packed. But
+if they should be soft, very flexible, and discharge a discoloured
+bloody mucus, they must be put back in spirits at least 20° over proof.
+Specimens showing distinct signs of decomposition should be thrown
+away, as they imperil all other specimens in the same vessel. Neither
+should any specimen in which decomposition has commenced when found, be
+received for the collecting boxes, unless it be of a very rare species,
+when the attempt may be made to preserve it separately in the strongest
+spirits available. The fresher the specimens to be preserved are, the
+better is the chance of keeping them in a perfect condition. Specimens
+which have lost their scales, or are otherwise much injured, should not
+be kept. Herring-like fishes, and others with deciduous scales, are
+better wrapped in thin paper or linen before being placed in spirits.</p>
+
+<p>The spirits used during this all-important process of preservation
+loses, of course, gradually in strength. As long as it keeps 10° under
+proof it may still be used for the first stage of preservation, but
+weaker spirits should be re-distilled; or, if the collector cannot do
+this, it should be at least filtered through powdered charcoal before
+it is mixed with stronger spirits. Many collectors are satisfied with
+removing the thick sediment collected at the bottom of the vessel,
+and use their spirits over and over again without removing from it by
+filtration the decomposing matter with which it has been impregnated,
+and which entirely neutralises the preserving property of the spirits.
+The result is generally the loss of the collection on its journey
+home. The collector can easily detect the vitiated character of his
+spirits by its bad smell. He must frequently examine his specimens; and
+attention to the rules given, with a little practice and perseverance,
+after the possible failure of the first trial, will soon insure to
+him the safety of his collected treasures. The trouble of collecting
+specimens in spirits is infinitely less than that of preserving skins
+or dry specimens of any kind.</p>
+
+<p>When a sufficient number of well-preserved examples have been brought
+together, they should be sent home by the earliest opportunity. Each
+specimen should be wrapped separately in a piece of linen, or at least
+soft paper; the specimens are then packed as close as herrings in the
+zinc case, so that no free space<span class="pagenum" id="Page_701">[701]</span> is left either at the top or on the
+sides. When the case is full, the lid is soldered on, with a round
+hole about half an inch in diameter near one of the corners. This hole
+is left in order to pour the spirit through it into the case. Care is
+taken to drive out the air which may remain between the specimens,
+and to surround them completely with spirits, until the case is quite
+full. Finally, the hole is closed by a small square lid of tin being
+soldered over it. In order to see whether the case keeps in the spirit
+perfectly, it is turned upside down and left over night. When all is
+found to be securely fastened, the zinc case is placed into the wooden
+box and ready for transport.</p>
+
+<p>Now and then it happens in tropical climates that collectors are unable
+to keep fishes from decomposition even in the strongest spirits without
+being able to detect the cause. In such cases a remedy will be found in
+mixing a small quantity of arsenic or sublimate with the spirits; but
+the collector ought to inform his correspondent, or the recipient of
+the collection, of this admixture having been made.</p>
+
+<p>In former times fishes of every kind, even those of small size, were
+preserved dry as flat skins or stuffed. Specimens thus prepared admit
+of a very superficial examination only, and therefore this method of
+conservation has been abandoned in all larger museums, and should be
+employed exceptionally only, for instance on long voyages overland,
+during which, owing to the difficulty of transport, neither spirits
+nor vessels can be carried. To make up as much as possible for the
+imperfection of such specimens, the collector ought to sketch the
+fish before it is skinned, and to colour the sketch if the species
+is ornamented with colours likely to disappear in the dry example.
+Collectors who have the requisite time and skill, ought to accompany
+their collections with drawings coloured from the living fishes; but
+at the same time it must be remembered that, valuable as such drawings
+are if accompanied by the originals from which they were made, they can
+never replace the latter, and possess a subordinate scientific value
+only.</p>
+
+<p>Very large fishes can be preserved as skins only; and collectors are
+strongly recommended to prepare in this manner the largest examples
+obtainable, although it will entail some trouble<span class="pagenum" id="Page_702">[702]</span> and expense. So
+very few large examples are exhibited in museums, the majority of the
+species being known from the young stage only, that the collector will
+find himself amply recompensed by attending to these desiderata.</p>
+
+<p>Scaly fishes are skinned thus: with a strong pair of scissors an
+incision is made along the median line of the abdomen from the foremost
+part of the throat, passing on one side of the base of the ventral
+and anal fins, to the root of the caudal fin, the cut being continued
+upwards to the back of the tail close to the base of the caudal. The
+skin of one side of the fish is then severed with the scalpel from the
+underlying muscles to the median line of the back; the bones which
+support the dorsal and caudal are cut through, so that these fins
+remain attached to the skin. The removal of the skin of the opposite
+side is easy. More difficult is the preparation of the head and
+scapulary region; the two halves of the scapular arch which have been
+severed from each other by the first incision are pressed towards the
+right and left, and the spine is severed behind the head, so that now
+only the head and shoulder bones remain attached to the skin. These
+parts have to be cleaned from the inside, all soft parts, the branchial
+and hyoid apparatus, and all smaller bones, being cut away with the
+scissors or scraped off with the scalpel. In many fishes, which
+are provided with a characteristic dental apparatus in the pharynx
+(Labroids, Cyprinoids), the pharyngeal bones ought to be preserved,
+and tied with a thread to the specimen. The skin being now prepared so
+far, its entire inner surface as well as the inner side of the head are
+rubbed with arsenical soap; cotton-wool, or some other soft material is
+inserted into any cavities or hollows, and finally a thin layer of the
+same material is placed between the two flaps of the skin. The specimen
+is then dried under a slight weight to keep it from shrinking.</p>
+
+<p>The scales of some fishes, as for instance of many kinds of herrings,
+are so delicate and deciduous that the mere handling causes them to rub
+off easily. Such fishes may be covered with thin paper (tissue-paper
+is the best), which is allowed to dry on them before skinning. There
+is no need for removing the paper before the specimen has reached its
+destination.</p>
+
+<p><span class="pagenum" id="Page_703">[703]</span></p>
+
+<p>Scaleless Fishes, as Siluroids and Sturgeons, are skinned in the same
+manner, but the skin can be rolled up over the head; such skins can
+also be preserved in spirits, in which case the traveller may save to
+himself the trouble of cleaning the head.</p>
+
+<p>Some Sharks are known to attain to a length of 30 feet, and some Rays
+to a width of 20 feet. The preservation of such gigantic specimens is
+much to be recommended, and although the difficulties of preserving
+fishes increase with their size, the operation is facilitated, because
+the skins of all Sharks and Rays can easily be preserved in salt and
+strong brine. Sharks are skinned much in the same way as ordinary
+fishes. In Rays an incision is made not only from the snout to the end
+of the fleshy part of the tail, but also a second across the widest
+part of the body. When the skin is removed from the fish, it is placed
+into a cask with strong brine mixed with alum, the head occupying the
+upper part of the cask; this is necessary, because this part is most
+likely to show signs of decomposition, and therefore most requires
+supervision. When the preserving fluid has become decidedly weaker from
+the extracted blood and water, it is thrown away and replaced by fresh
+brine. After a week’s or fortnight’s soaking the skin is taken out of
+the cask to allow the fluid to drain off; its inner side is covered
+with a thin layer of salt, and after being rolled up (the head being
+inside) it is packed in a cask, the bottom of which is covered with
+salt; all the interstices and the top are likewise filled with salt.
+The cask must be perfectly water-tight.</p>
+
+<p>Of all larger examples of which the skin is prepared, the measurements
+should be taken before skinning so as to guide the taxidermist in
+stuffing and mounting the specimens.</p>
+
+<p>Skeletons of large osseous fishes are as valuable as their skins. To
+preserve them it is only necessary to remove the soft parts of the
+abdominal cavity and the larger masses of muscle, the bones being left
+in their natural continuity. The remaining flesh is allowed to dry on
+the bones, and can be removed by proper maceration at home. The fins
+ought to be as carefully attended to as in a skin, and of scaly fishes
+so much of the external skin ought to be preserved as is necessary
+for the determination of the species, as otherwise it is generally
+impossible to determine more than the genus.</p>
+
+<p><span class="pagenum" id="Page_704">[704]</span></p>
+
+<p>A few remarks may be added as regards those Faunæ, which promise most
+results to the explorer, with some hints as to desirable information on
+the life and economic value of fishes.</p>
+
+<p>It is surprising to find how small the number is of the freshwater
+faunæ which may be regarded as well explored; the rivers of Central
+Europe, the Lower Nile, the lower and middle course of the Ganges,
+and the lower part of the Amazons are almost the only fresh waters
+in which collections made without discrimination would not reward
+the naturalist. The oceanic areas are much better known; yet almost
+everywhere novel forms can be discovered and new observations
+made. Most promising and partly quite unknown are the following
+districts:—the Arctic Ocean, all coasts south of 38° lat. S., the
+Cape of Good Hope, the Persian Gulf, the coasts of Australia (with the
+exception of Tasmania, New South Wales, and New Zealand), many of the
+little-visited groups of Pacific islands, the coasts of north-eastern
+Asia north of 35° lat. N., and the western coasts of North and South
+America.</p>
+
+<p>No opportunity should be lost to obtain <i>pelagic</i> forms,
+especially the young larva-like stages of development abounding on the
+surface of the open ocean. They can be obtained without difficulty by
+means of a small narrow meshed net dragged behind the ship. The sac
+of the net is about 3 feet deep, and fastened to a strong brass-ring
+2 or 2½ feet in diameter. The net is suspended by three lines passing
+into the strong main line. It can only be used when the vessel moves
+very slowly, its speed not exceeding three knots an hour, or when a
+current passes the ship whilst at anchor. To keep the net in a vertical
+position the ring can be weighted at one point of its circumference;
+and by using heavier weights two or three drag-nets can be used
+simultaneously at different depths. This kind of fishing should be
+tried at night as well as day, as many fishes come to the surface only
+after sunset. The net must not be left long in the water, from 5 to 20
+minutes only, as delicate objects would be sure to be destroyed by the
+force of the water passing through the meshes.</p>
+
+<p>Objects found floating on the surface, as wood, baskets, seaweed,
+etc., deserve the attention of the travellers, as they are generally
+surrounded by small fishes or other marine animals.</p>
+
+<p><span class="pagenum" id="Page_705">[705]</span></p>
+
+<p>It is of the greatest importance to note the longitude and latitude at
+which the objects were collected in the open ocean.</p>
+
+<p>Fishing in great depths by means of the dredge, can be practised
+only from vessels specially fitted out for the purpose; and the
+success which attended the “Challenger,” and North American Deep-sea
+explorations, has developed Deep-sea fishing into such a speciality
+that the requisite information can be gathered better by consulting the
+reports of those expeditions than from a general account, such as could
+be given in the present work.</p>
+
+<p>Fishes offer an extraordinary variety with regard to their habits,
+growth, etc., so that it is impossible to enumerate in detail the
+points of interest to which the travellers should pay particular
+attention. However, the following hints may be useful.</p>
+
+<p>Above all, detailed accounts are desirable of all fishes forming
+important articles of trade, or capable of becoming more generally
+useful than they are at present. Therefore, deserving of special
+attention are the Sturgeons, Gadoids, Thyrsites and Chilodactylus,
+Salmonoids, Clupeoids. Wherever these fishes are found in sufficient
+abundance, new sources may be opened to trade.</p>
+
+<p>Exact observations should be made on the fishes the flesh of which is
+poisonous either constantly or at certain times and certain localities;
+the cause of the poisonous qualities as well as the nature of the
+poison should be ascertained. Likewise the poison of fishes provided
+with special poison-organs requires to be experimentally examined,
+especially with regard to its effects on other fishes and animals
+generally.</p>
+
+<p>All observations directed to sex, mode of propagation, and development,
+will have special interest: thus those relating to secondary sexual
+characters, hermaphroditism, numeric proportion of the sexes, time of
+spawning and migration, mode of spawning, construction of nests, care
+of progeny, change of form during growth, etc.</p>
+
+<p>If the collector is unable to preserve the largest individuals of a
+species that may come under his observation he should note at least
+their measurements. There are but few species of fishes of which the
+limit of growth is known.</p>
+
+<p>The history of Parasitic Fishes is almost unknown, and any<span class="pagenum" id="Page_706">[706]</span>
+observations with regard to their relation to their host as well as to
+their early life will prove to be valuable; nothing is known of the
+propagation of fishes even so common as Echeneis and Fierasfer, much
+less of the parasitic Freshwater Siluroids.</p>
+
+<p>The temperature of the blood of the larger freshwater and marine
+species should be exactly measured.</p>
+
+<p>Many pelagic and deep-sea fishes are provided with peculiar small
+round organs of a mother-of-pearl colour, distributed in series along
+the side of the body, especially along the abdomen. Some zoologists
+consider these organs as accessory eyes, others (and it appears to
+us with better reason) as luminous organs. They deserve an accurate
+microscopic examination made on fresh specimens; and their function
+should be ascertained from observation of the living fishes, especially
+also with regard to the question, whether or not the luminosity (if
+such be their function) is subject to the will of the fish.</p>
+
+  <div class="figcenter" id="fig321" style="max-width: 700px">
+     <img
+    class="p1"   
+    src="images/fig321.jpg"
+     alt="">
+     <p class="p0 center smaller">Fig. 321.—Scopelus boops, a pelagic fish, with luminous
+organs.</p>
+  </div>
+
+<hr class="chap x-ebookmaker-drop">
+
+<div class="chapter">
+<p><span class="pagenum" id="Page_707">[707]</span></p>
+
+<h2 id="INDEX">INDEX.</h2>
+</div>
+
+  <div class="figcenter">
+    <img
+    class="p0" 
+    src="images/a003_deco.jpg"
+    alt="">
+  </div>
+
+<ul>
+  <li>Abdominal Cavity,
+    <a href="#Page_123">123</a></li>
+
+  <li>Abdominal fins,
+    <a href="#Page_42">42</a></li>
+
+  <li>Abramis,
+    <a href="#Page_602">602</a></li>
+
+  <li>Abrostomus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Acanthaphritis,
+    <a href="#Page_466">466</a></li>
+
+  <li>Acanthias,
+    <a href="#Page_331">331</a></li>
+
+  <li>Acanthicus,
+    <a href="#Page_576">576</a></li>
+
+  <li>Acanthobrama,
+    <a href="#Page_604">604</a></li>
+
+  <li>Acanthoclinus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Acanthodes,
+    <a href="#Page_355">355</a></li>
+
+  <li>Acanthodini,
+    <a href="#Page_355">355</a></li>
+
+  <li>Acantholabrus,
+    <a href="#Page_528">528</a></li>
+
+  <li>Acanthonus,
+    <a href="#Page_547">547</a></li>
+
+  <li>Acanthophthalmus,
+    <a href="#Page_606">606</a></li>
+
+  <li>Acanthopsis,
+    <a href="#Page_606">606</a></li>
+
+  <li>Acanthopterygiau,
+    <a href="#Page_41">41</a></li>
+
+  <li>Acanthopterygii,
+    <a href="#Page_374">374</a></li>
+
+  <li>Acanthorhodeus,
+    <a href="#Page_601">601</a></li>
+
+  <li>Acanthurus,
+    <a href="#Page_438">438</a>,
+    <a href="#Page_439">439</a></li>
+
+  <li>Acanus,
+    <a href="#Page_421">421</a></li>
+
+  <li>Acara,
+    <a href="#Page_536">536</a></li>
+
+  <li>Acclimatisation,
+    <a href="#Page_185">185</a></li>
+
+  <li>Acentronura,
+    <a href="#Page_683">683</a></li>
+
+  <li>Acerina,
+    <a href="#Page_378">378</a></li>
+
+  <li>Acestra,
+    <a href="#Page_579">579</a></li>
+
+  <li>Achilognathus,
+    <a href="#Page_601">601</a></li>
+
+  <li>Acipenser,
+    <a href="#Page_361">361</a></li>
+
+  <li>Acipenseridæ,
+    <a href="#Page_360">360</a></li>
+
+  <li>Acrochilus,
+    <a href="#Page_601">601</a></li>
+
+  <li>Acrochordonichthys,
+    <a href="#Page_567">567</a></li>
+
+  <li>Acrodus,
+    <a href="#Page_330">330</a></li>
+
+  <li>Acrogaster,
+    <a href="#Page_421">421</a></li>
+
+  <li>Acrognathus,
+    <a href="#Page_631">631</a></li>
+
+  <li>Acrolepis,
+    <a href="#Page_370">370</a></li>
+
+  <li>Acronuridæ,
+    <a href="#Page_438">438</a></li>
+
+  <li>Acronurus,
+    <a href="#Page_439">439</a></li>
+
+  <li>Acropoma,
+    <a href="#Page_395">395</a></li>
+
+  <li>Acyprinoid division,
+    <a href="#Page_218">218</a></li>
+
+  <li>Adipose eyelid,
+    <a href="#Page_113">113</a></li>
+
+  <li>Adipose fin,
+    <a href="#Page_42">42</a></li>
+
+  <li>Aegæonichthys,
+    <a href="#Page_476">476</a></li>
+
+  <li>Aellopos,
+    <a href="#Page_325">325</a></li>
+
+  <li>Aelurichthys,
+    <a href="#Page_569">569</a></li>
+
+  <li>Aesopia,
+    <a href="#Page_558">558</a></li>
+
+  <li>Aëtobatis,
+    <a href="#Page_345">345</a></li>
+
+  <li>African region,
+    <a href="#Page_227">227</a></li>
+
+  <li>Agassiz,
+    <a href="#Page_20">20</a>,
+    <a href="#Page_31">31</a>,
+    <a href="#Page_32">32</a></li>
+
+  <li>Ageniosus,
+    <a href="#Page_572">572</a></li>
+
+  <li>Agnus,
+    <a href="#Page_463">463</a></li>
+
+  <li>Agoniates,
+    <a href="#Page_610">610</a></li>
+
+  <li>Agonostoma,
+    <a href="#Page_504">504</a></li>
+
+  <li>Agonus,
+    <a href="#Page_480">480</a></li>
+
+  <li>Agrammus,
+    <a href="#Page_491">491</a></li>
+
+  <li>Agriopus,
+    <a href="#Page_416">416</a></li>
+
+  <li>Ailia,
+    <a href="#Page_566">566</a></li>
+
+  <li>Aipichthys,
+    <a href="#Page_441">441</a></li>
+
+  <li>Air-bladder,
+    <a href="#Page_142">142</a></li>
+
+  <li>Akysis,
+    <a href="#Page_567">567</a></li>
+
+  <li>Albacore,
+    <a href="#Page_458">458</a></li>
+
+  <li>Albinism,
+    <a href="#Page_183">183</a></li>
+
+  <li>Alborella,
+    <a href="#Page_604">604</a></li>
+
+  <li>Albula,
+    <a href="#Page_660">660</a></li>
+
+  <li>Albulichthys,
+    <a href="#Page_596">596</a></li>
+
+  <li>Alburnus,
+    <a href="#Page_603">603</a></li>
+
+  <li>Alepocephalus,
+    <a href="#Page_664">664</a></li>
+
+  <li>Alestes,
+    <a href="#Page_608">608</a></li>
+
+  <li>Ale-wife,
+    <a href="#Page_659">659</a></li>
+
+  <li>Alisphenoid,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_88">88</a></li>
+
+  <li>Allice Shad,
+    <a href="#Page_659">659</a></li>
+
+  <li>Alopecias,
+    <a href="#Page_322">322</a></li>
+
+  <li>Ambassis,
+    <a href="#Page_393">393</a></li>
+
+  <li>Amblyopsis,
+    <a href="#Page_618">618</a></li>
+
+  <li>Amblyopus,
+    <a href="#Page_489">489</a></li>
+
+  <li>Amblypharyngodon,
+    <a href="#Page_598">598</a></li>
+
+  <li>Amblypterus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Amblyrhynchichthys,
+    <a href="#Page_596">596</a></li>
+
+  <li>Amia,
+    <a href="#Page_372">372</a></li>
+
+  <li>Amioidei,
+    <a href="#Page_370">370</a></li>
+
+  <li>Amiurus,
+    <a href="#Page_567">567</a></li>
+
+  <li>Ammocoetes,
+    <a href="#Page_693">693</a></li>
+
+  <li>Ammodytes,
+    <a href="#Page_550">550</a></li>
+
+  <li>Ammopleurops,
+    <a href="#Page_559">559</a></li>
+
+  <li>Ammotretis,
+    <a href="#Page_557">557</a></li>
+
+  <li>Amphioxus,
+    <a href="#Page_696">696</a></li>
+
+  <li>Amphipnous,
+    <a href="#Page_668">668</a></li>
+
+  <li>Amphiprion,
+    <a href="#Page_525">525</a></li>
+
+  <li>Amphisile,
+    <a href="#Page_509">509</a></li>
+
+  <li>Amphistium,
+    <a href="#Page_442">442</a></li>
+
+  <li>Anabas,
+    <a href="#Page_516">516</a></li>
+
+  <li>Anableps,
+    <a href="#Page_617">617</a></li>
+
+  <li>Anacanthini,
+    <a href="#Page_537">537</a></li>
+
+  <li>Anacanthus,
+    <a href="#Page_684">684</a></li>
+
+  <li>Anacyrtus,
+    <a href="#Page_611">611</a></li>
+
+  <li>Anal fin,
+    <a href="#Page_40">40</a>,
+    <a href="#Page_42">42</a></li>
+
+  <li>Anampses,
+    <a href="#Page_529">529</a></li>
+
+  <li>Anapterus,
+    <a href="#Page_582">582</a></li>
+
+  <li>Anarrhichas,
+    <a href="#Page_492">492</a></li>
+
+  <li>Anastomus,
+    <a href="#Page_608">608</a></li>
+
+  <li>Anchovy,
+    <a href="#Page_656">656</a></li>
+
+  <li>Ancistrodon,
+    <a href="#Page_319">319</a></li>
+
+  <li>Ancylodon,
+    <a href="#Page_430">430</a></li>
+
+  <li>Anema,
+    <a href="#Page_463">463</a></li>
+
+  <li>Anenchelum,
+    <a href="#Page_433">433</a></li>
+
+  <li>Angel-fish,
+    <a href="#Page_334">334</a></li>
+
+  <li>Angler,
+    <a href="#Page_470">470</a></li>
+
+  <li>Anguilla,
+    <a href="#Page_671">671</a></li>
+
+  <li>Angular bone,
+    <a href="#Page_54">54</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Anomalops,
+    <a href="#Page_449">449</a></li>
+
+  <li>Anoplogaster,
+    <a href="#Page_422">422</a></li>
+
+  <li>Antarctic ocean,
+    <a href="#Page_289">289</a></li>
+
+  <li>Antennarius,
+    <a href="#Page_473">473</a></li>
+
+  <li>Anthias,
+    <a href="#Page_380">380</a></li>
+
+  <li>Anticitharus,
+    <a href="#Page_556">556</a></li>
+
+  <li>Antigonia,
+    <a href="#Page_449">449</a></li>
+
+  <li>Aphanopus,
+    <a href="#Page_434">434</a></li>
+
+  <li>Aphareus,
+    <a href="#Page_390">390</a></li>
+
+  <li>Aphoristia,
+    <a href="#Page_559">559</a></li>
+
+  <li>Aphredoderus,
+    <a href="#Page_396">396</a></li>
+
+  <li>Aphritis,
+    <a href="#Page_466">466</a></li>
+
+  <li>Aphyocharax,
+    <a href="#Page_610">610</a></li>
+
+  <li>Aphyocypris,
+    <a href="#Page_598">598</a></li>
+
+  <li>Aphyonus,
+    <a href="#Page_548">548</a></li>
+
+  <li>Apionichthys,
+    <a href="#Page_559">559</a></li>
+
+  <li>Apistus,
+    <a href="#Page_415">415</a></li>
+
+  <li>Aploactis,
+    <a href="#Page_417">417</a></li>
+
+  <li>Apocryptes,
+    <a href="#Page_487">487</a></li>
+
+  <li>Apodichthys,
+    <a href="#Page_496">496</a></li>
+
+  <li>Apogon,
+    <a href="#Page_394">394</a></li>
+
+  <li>Apophyses,
+    <a href="#Page_51">51</a></li>
+
+  <li>Appendices pyloricæ,
+    <a href="#Page_131">131</a></li>
+
+  <li>Aprion,
+    <a href="#Page_397">397</a></li>
+
+  <li>Apsilus,
+    <a href="#Page_397">397</a></li>
+
+  <li>Apua,
+    <a href="#Page_606">606</a></li>
+
+  <li>Arapaima,
+    <a href="#Page_654">654</a></li>
+
+  <li>Archæus,
+    <a href="#Page_442">442</a></li>
+
+  <li>Archipterygium,
+    <a href="#Page_74">74</a></li>
+
+  <li>Arctic ocean,
+    <a href="#Page_261">261</a></li>
+
+  <li>Arctic zone,
+    <a href="#Page_241">241</a></li>
+
+  <li>Argentina,
+    <a href="#Page_650">650</a></li>
+
+  <li>Arges,
+    <a href="#Page_575">575</a></li>
+
+  <li>Argyropelecus,
+    <a href="#Page_628">628</a></li>
+
+  <li>Argyriosus,
+    <a href="#Page_443">443</a></li>
+
+  <li>Aristotle,
+    <a href="#Page_1">1</a></li>
+
+  <li>Arius,
+    <a href="#Page_569">569</a></li>
+
+  <li>Arnoglossus,
+    <a href="#Page_556">556</a></li>
+
+  <li>Arrhamphus,
+    <a href="#Page_621">621</a></li>
+
+  <li>Arripis,
+    <a href="#Page_393">393</a></li>
+
+  <li>Artedi,
+    <a href="#Page_9">9</a></li>
+
+  <li>Artedius,
+    <a href="#Page_480">480</a></li>
+
+  <li>Arthropterus,
+    <a href="#Page_342">342</a></li>
+
+  <li>Articulary bone,
+    <a href="#Page_54">54</a>,
+    <a href="#Page_90">90</a></li>
+
+  <li>Articulated rays,
+    <a href="#Page_40">40</a></li>
+
+  <li>Asima,
+    <a href="#Page_405">405</a></li>
+
+  <li>Aspidoparia,
+    <a href="#Page_602">602</a></li>
+
+  <li>Aspidophoroides,
+    <a href="#Page_480">480</a></li>
+
+  <li>Aspidorhynchidæ,
+    <a href="#Page_369">369</a></li>
+
+  <li>Aspius,
+    <a href="#Page_603">603</a></li>
+
+  <li>Aspredo,
+    <a href="#Page_580">580</a></li>
+
+  <li>Aspro,
+    <a href="#Page_379">379</a></li>
+
+  <li>Astracanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Astrape,
+    <a href="#Page_340">340</a></li>
+
+  <li>Astrolepis,
+    <a href="#Page_354">354</a></li>
+
+  <li>Astronesthes,
+    <a href="#Page_629">629</a></li>
+
+  <li>Astrophysus,
+    <a href="#Page_572">572</a></li>
+
+  <li>Astroplebus,
+    <a href="#Page_575">575</a></li>
+
+  <li>Astroptychius,
+    <a href="#Page_314">314</a></li>
+
+  <li>Ateleopus,
+    <a href="#Page_553">553</a></li>
+
+  <li>Atherina,
+    <a href="#Page_500">500</a></li>
+
+  <li>Atherinichthys,
+    <a href="#Page_501">501</a></li>
+
+  <li>Atlantic, tropical,
+    <a href="#Page_278">278</a></li>
+
+  <li>Atlantic, northern,
+    <a href="#Page_262">262</a></li>
+
+  <li>Atopochilus,
+    <a href="#Page_570">570</a></li>
+
+  <li>Atopomycterus,
+    <a href="#Page_689">689</a></li>
+
+  <li>Atypichthys,
+    <a href="#Page_402">402</a></li>
+
+  <li>Auchenaspis,
+    <a href="#Page_354">354</a></li>
+
+  <li>Auchenipterus,
+    <a href="#Page_572">572</a></li>
+
+  <li>Auchenoglanis,
+    <a href="#Page_569">569</a></li>
+
+  <li>Aulacocephalus,
+    <a href="#Page_383">383</a></li>
+
+  <li>Aulolepis,
+    <a href="#Page_631">631</a></li>
+
+  <li>Aulichthys,
+    <a href="#Page_508">508</a></li>
+
+  <li>Auliscops,
+    <a href="#Page_507">507</a>,
+    <a href="#Page_508">508</a></li>
+
+  <li>Aulopus,
+    <a href="#Page_587">587</a></li>
+
+  <li>Aulopyge,
+    <a href="#Page_596">596</a></li>
+
+  <li>Aulorhynchus,
+    <a href="#Page_508">508</a></li>
+
+  <li>Aulostoma,
+    <a href="#Page_507">507</a>,
+    <a href="#Page_508">508</a></li>
+
+  <li>Ausonia,
+    <a href="#Page_455">455</a></li>
+
+  <li>Ausonius,
+    <a href="#Page_3">3</a></li>
+
+  <li>Autochthont,
+    <a href="#Page_214">214</a></li>
+
+  <li>Autostylic skull,
+    <a href="#Page_71">71</a></li>
+
+  <li>Auxis,
+    <a href="#Page_459">459</a></li>
+
+  <li>Avola,
+    <a href="#Page_604">604</a></li>
+</ul>
+
+<ul>
+  <li>Badis,
+    <a href="#Page_418">418</a></li>
+
+  <li>Baer,
+    <a href="#Page_32">32</a></li>
+
+  <li>Bagarius,
+    <a href="#Page_570">570</a></li>
+
+  <li>Bagrichthys,
+    <a href="#Page_567">567</a></li>
+
+  <li>Bagroides,
+    <a href="#Page_567">567</a></li>
+
+  <li>Bagropsis,
+    <a href="#Page_568">568</a></li>
+
+  <li>Bagrus,
+    <a href="#Page_567">567</a></li>
+
+  <li>Baird,
+    <a href="#Page_29">29</a></li>
+
+  <li>Bakker,
+    <a href="#Page_32">32</a></li>
+
+  <li>Balfour,
+    <a href="#Page_32">32</a>,
+    <a href="#Page_33">33</a></li>
+
+  <li>Balistes,
+    <a href="#Page_684">684</a></li>
+
+  <li>Ballan Wrasse,
+    <a href="#Page_527">527</a></li>
+
+  <li>Band-fish,
+    <a href="#Page_490">490</a></li>
+
+  <li>Barbel,
+    <a href="#Page_594">594</a></li>
+
+  <li>Barbels,
+    <a href="#Page_37">37</a></li>
+
+  <li>Barbichthys,
+    <a href="#Page_596">596</a></li>
+
+  <li>Barbus,
+    <a href="#Page_594">594</a></li>
+
+  <li>Barilius,
+    <a href="#Page_602">602</a></li>
+
+  <li>Barracuda,
+    <a href="#Page_437">437</a>,
+    <a href="#Page_499">499</a></li>
+
+  <li>Barramunda,
+    <a href="#Page_357">357</a></li>
+
+  <li>Barynotus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Basibranchial,
+    <a href="#Page_58">58</a></li>
+
+  <li>Basihyal,
+    <a href="#Page_58">58</a></li>
+
+  <li>Basioccipital,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_87">87</a></li>
+
+  <li>Basisphenoid,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Basking shark,
+    <a href="#Page_322">322</a></li>
+
+  <li>Bass,
+    <a href="#Page_376">376</a></li>
+
+  <li>Bastard Dorey,
+    <a href="#Page_388">388</a></li>
+
+  <li>Bathydraco,
+    <a href="#Page_465">465</a></li>
+
+  <li>Bathygadus,
+    <a href="#Page_552">552</a></li>
+
+  <li>Bathylagus,
+    <a href="#Page_650">650</a></li>
+
+  <li>Bathynectes,
+    <a href="#Page_547">547</a></li>
+
+  <li>Bathyophis,
+    <a href="#Page_629">629</a></li>
+
+  <li>Bathypterois,
+    <a href="#Page_583">583</a></li>
+
+  <li>Bathysaurus,
+    <a href="#Page_582">582</a></li>
+
+  <li>Bathythrissa,
+    <a href="#Page_668">668</a></li>
+
+  <li>Bathytroctes,
+    <a href="#Page_664">664</a></li>
+
+  <li>Batoidei,
+    <a href="#Page_335">335</a></li>
+
+  <li>Batrachocephalus,
+    <a href="#Page_570">570</a></li>
+
+  <li>Batrachus,
+    <a href="#Page_467">467</a></li>
+
+  <li>Bayad,
+    <a href="#Page_567">567</a></li>
+
+  <li>Bdellostoma,
+    <a href="#Page_695">695</a></li>
+
+  <li>Becker,
+    <a href="#Page_408">408</a></li>
+
+  <li>Bellows-fish,
+    <a href="#Page_509">509</a></li>
+
+  <li>Belodontichthys,
+    <a href="#Page_566">566</a></li>
+
+  <li>Belon,
+    <a href="#Page_3">3</a></li>
+
+  <li>Belone,
+    <a href="#Page_620">620</a></li>
+
+  <li>Belonesox,
+    <a href="#Page_617">617</a></li>
+
+  <li>Belonostomus,
+    <a href="#Page_369">369</a></li>
+
+  <li>Bembras,
+    <a href="#Page_480">480</a></li>
+
+  <li>Benedenius,
+    <a href="#Page_370">370</a></li>
+
+  <li>Benthophilus,
+    <a href="#Page_489">489</a></li>
+
+  <li>Berycidæ,
+    <a href="#Page_420">420</a></li>
+
+  <li>Berycopsis,
+    <a href="#Page_421">421</a></li>
+
+  <li>Beryx,
+    <a href="#Page_422">422</a></li>
+
+  <li>Betta,
+    <a href="#Page_518">518</a></li>
+
+  <li>Bib,
+    <a href="#Page_541">541</a></li>
+
+  <li>Bichir,
+    <a href="#Page_364">364</a></li>
+
+  <li>Bitterling,
+    <a href="#Page_601">601</a></li>
+
+  <li>Black Bass,
+    <a href="#Page_393">393</a></li>
+
+  <li>Black-fish,
+    <a href="#Page_452">452</a>,
+    <a href="#Page_527">527</a></li>
+
+  <li>Black Head,
+    <a href="#Page_596">596</a></li>
+
+  <li>Black Horses,
+    <a href="#Page_589">589</a></li>
+
+  <li>Black Sea-bream,
+    <a href="#Page_406">406</a></li>
+
+  <li>Blanchard,
+    <a href="#Page_28">28</a></li>
+
+  <li>Bleak,
+    <a href="#Page_604">604</a></li>
+
+  <li>Bleeker,
+    <a href="#Page_30">30</a></li>
+
+  <li>Bleekeria,
+    <a href="#Page_550">550</a></li>
+
+  <li>Blenniidæ,
+    <a href="#Page_492">492</a></li>
+
+  <li>Blenniops,
+    <a href="#Page_496">496</a></li>
+
+  <li>Blennius,
+    <a href="#Page_493">493</a></li>
+
+  <li>Blennodesmus,
+    <a href="#Page_538">538</a></li>
+
+  <li>Blennophis,
+    <a href="#Page_498">498</a></li>
+
+  <li>Blenny,
+    <a href="#Page_492">492</a></li>
+
+  <li>Blepsias,
+    <a href="#Page_480">480</a></li>
+
+  <li>Blind fish,
+    <a href="#Page_618">618</a></li>
+
+  <li>Bloch,
+    <a href="#Page_13">13</a></li>
+
+  <li>Blood-corpuscles,
+    <a href="#Page_150">150</a></li>
+
+  <li>Blue-fish,
+    <a href="#Page_447">447</a></li>
+
+  <li>Boar-fish,
+    <a href="#Page_388">388</a>,
+    <a href="#Page_449">449</a></li>
+
+  <li>Bocage,
+    <a href="#Page_28">28</a></li>
+
+  <li>Bocourt,
+    <a href="#Page_31">31</a></li>
+
+  <li>Bola,
+    <a href="#Page_602">602</a></li>
+
+  <li>Boleophthalmus,
+    <a href="#Page_487">487</a></li>
+
+  <li>Boleosoma,
+    <a href="#Page_379">379</a></li>
+
+  <li>Bolty,
+    <a href="#Page_535">535</a></li>
+
+  <li>Bombay-duck,
+    <a href="#Page_584">584</a></li>
+
+  <li>Bonaparte,
+    <a href="#Page_28">28</a></li>
+
+  <li>Bonelli,
+    <a href="#Page_7">7</a></li>
+
+  <li>Bonito,
+    <a href="#Page_458">458</a></li>
+
+  <li>Bony Pike,
+    <a href="#Page_367">367</a></li>
+
+  <li>Borer,
+    <a href="#Page_694">694</a></li>
+
+  <li>Botia,
+    <a href="#Page_605">605</a></li>
+
+  <li>Bovichthys,
+    <a href="#Page_465">465</a></li>
+
+  <li>Bow-fin,
+    <a href="#Page_372">372</a></li>
+
+  <li>Box,
+    <a href="#Page_406">406</a></li>
+
+  <li>Brachionichthys,
+    <a href="#Page_474">474</a></li>
+
+  <li>Brachymystax,
+    <a href="#Page_646">646</a></li>
+
+  <li>Brachypleura,
+    <a href="#Page_556">556</a></li>
+
+  <li>Brackish water fishes,
+    <a href="#Page_250">250</a></li>
+
+  <li>Brain,
+    <a href="#Page_97">97</a></li>
+
+  <li>Brama,
+    <a href="#Page_454">454</a></li>
+
+  <li>Branched rays,
+    <a href="#Page_40">40</a></li>
+
+  <li>Branchiæ,
+    <a href="#Page_136">136</a></li>
+
+  <li>Branchial arches,
+    <a href="#Page_58">58</a></li>
+
+  <li>Branchiostegals,
+    <a href="#Page_39">39</a>,
+    <a href="#Page_58">58</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Branchiostoma,
+    <a href="#Page_696">696</a></li>
+
+  <li>Bream,
+    <a href="#Page_602">602</a></li>
+
+  <li>Bregmaceros,
+    <a href="#Page_545">545</a></li>
+
+  <li>Brill,
+    <a href="#Page_555">555</a></li>
+
+  <li>British district,
+    <a href="#Page_263">263</a></li>
+
+  <li>Brontes,
+    <a href="#Page_575">575</a></li>
+
+  <li>Brook-trout,
+    <a href="#Page_646">646</a></li>
+
+  <li>Brosmius,
+    <a href="#Page_546">546</a></li>
+
+  <li>Brotula,
+    <a href="#Page_546">546</a></li>
+
+  <li>Brotulophis,
+    <a href="#Page_549">549</a></li>
+
+  <li>Brünnich,
+    <a href="#Page_13">13</a></li>
+
+  <li>Brycon,
+    <a href="#Page_610">610</a></li>
+
+  <li>Bryconæthiops,
+    <a href="#Page_610">610</a></li>
+
+  <li>Bryconops,
+    <a href="#Page_610">610</a></li>
+
+  <li>Bryttus,
+    <a href="#Page_396">396</a></li>
+
+  <li>Buccal cavity,
+    <a href="#Page_123">123</a></li>
+
+  <li>Bulbus aortæ,
+    <a href="#Page_152">152</a></li>
+
+  <li>Bull-head,
+    <a href="#Page_476">476</a></li>
+
+  <li>Bull-trout,
+    <a href="#Page_644">644</a></li>
+
+  <li>Bulti,
+    <a href="#Page_535">535</a></li>
+
+  <li>Buffaloe,
+    <a href="#Page_589">589</a></li>
+
+  <li>Bummaloh,
+    <a href="#Page_584">584</a></li>
+
+  <li>Bungia,
+    <a href="#Page_596">596</a></li>
+
+  <li>Bunocephalichthys,
+    <a href="#Page_580">580</a></li>
+
+  <li>Bunocephalus,
+    <a href="#Page_580">580</a></li>
+
+  <li>Bunocottus,
+    <a href="#Page_480">480</a></li>
+
+  <li>Burbot,
+    <a href="#Page_544">544</a></li>
+
+  <li>Bursa entiana,
+    <a href="#Page_128">128</a></li>
+
+  <li>Burton Skate,
+    <a href="#Page_341">341</a></li>
+
+  <li>Butter-fish,
+    <a href="#Page_496">496</a>,
+    <a href="#Page_533">533</a></li>
+
+  <li>Bynni,
+    <a href="#Page_594">594</a></li>
+
+  <li>Bythites,
+    <a href="#Page_549">549</a></li>
+</ul>
+
+<ul>
+  <li>Cachius,
+    <a href="#Page_604">604</a></li>
+
+  <li>Cænotropus,
+    <a href="#Page_607">607</a></li>
+
+  <li>Cæsio,
+    <a href="#Page_390">390</a></li>
+
+  <li>Calamoichthys,
+    <a href="#Page_364">364</a></li>
+
+  <li>Californian district,
+    <a href="#Page_271">271</a></li>
+
+  <li>Calamostoma,
+    <a href="#Page_680">680</a></li>
+
+  <li>Callanthias,
+    <a href="#Page_381">381</a></li>
+
+  <li>Callichrous,
+    <a href="#Page_566">566</a></li>
+
+  <li>Callichthys,
+    <a href="#Page_575">575</a></li>
+
+  <li>Callionymus,
+    <a href="#Page_489">489</a></li>
+
+  <li>Callipteryx,
+    <a href="#Page_462">462</a></li>
+
+  <li>Callomystax,
+    <a href="#Page_573">573</a></li>
+
+  <li>Callophysus,
+    <a href="#Page_569">569</a></li>
+
+  <li>Callorhynchus,
+    <a href="#Page_350">350</a></li>
+
+  <li>Callyodon,
+    <a href="#Page_532">532</a></li>
+
+  <li>Camper,
+    <a href="#Page_16">16</a></li>
+
+  <li>Campostoma,
+    <a href="#Page_596">596</a></li>
+
+  <li>Cantharina,
+    <a href="#Page_405">405</a></li>
+
+  <li>Cantharus,
+    <a href="#Page_405">405</a></li>
+
+  <li>Cantor,
+    <a href="#Page_30">30</a></li>
+
+  <li>Capelin,
+    <a href="#Page_647">647</a></li>
+
+  <li>Capello,
+    <a href="#Page_28">28</a></li>
+
+  <li>Cape of Good Hope,
+    <a href="#Page_283">283</a></li>
+
+  <li>Capitodus,
+    <a href="#Page_405">405</a></li>
+
+  <li>Capoëta,
+    <a href="#Page_593">593</a></li>
+
+  <li>Capros,
+    <a href="#Page_449">449</a></li>
+
+  <li>Carangidæ,
+    <a href="#Page_440">440</a></li>
+
+  <li>Carangopsis,
+    <a href="#Page_442">442</a></li>
+
+  <li>Caranx,
+    <a href="#Page_442">442</a></li>
+
+  <li>Carapus,
+    <a href="#Page_667">667</a></li>
+
+  <li>Carassius,
+    <a href="#Page_591">591</a></li>
+
+  <li>Carboniferous fishes,
+    <a href="#Page_196">196</a></li>
+
+  <li>Carcharias,
+    <a href="#Page_316">316</a></li>
+
+  <li>Carchariidæ,
+    <a href="#Page_316">316</a></li>
+
+  <li>Carcharodon,
+    <a href="#Page_320">320</a></li>
+
+  <li>Carcharopsis,
+    <a href="#Page_319">319</a></li>
+
+  <li>Cardlike teeth,
+    <a href="#Page_126">126</a></li>
+
+  <li>Caribe,
+    <a href="#Page_613">613</a></li>
+
+  <li>Carmoot,
+    <a href="#Page_563">563</a></li>
+
+  <li>Carp,
+    <a href="#Page_589">589</a></li>
+
+  <li>Carpals,
+    <a href="#Page_59">59</a></li>
+
+  <li>Carpiodes,
+    <a href="#Page_589">589</a></li>
+
+  <li>Cartilage-bones,
+    <a href="#Page_87">87</a></li>
+
+  <li>Castelnau,
+    <a href="#Page_31">31</a></li>
+
+  <li>Cataphracti,
+    <a href="#Page_480">480</a></li>
+
+  <li>Cat-fishes,
+    <a href="#Page_568">568</a></li>
+
+  <li>Catla,
+    <a href="#Page_592">592</a></li>
+
+  <li>Catopra,
+    <a href="#Page_418">418</a></li>
+
+  <li>Catoprion,
+    <a href="#Page_613">613</a></li>
+
+  <li>Catostomus,
+    <a href="#Page_589">589</a></li>
+
+  <li>Caturidæ,
+    <a href="#Page_371">371</a></li>
+
+  <li>Caudal fin,
+    <a href="#Page_40">40</a></li>
+
+  <li>Cebidichthys,
+    <a href="#Page_498">498</a></li>
+
+  <li>Central American district,
+    <a href="#Page_279">279</a></li>
+
+  <li>Centrarchus,
+    <a href="#Page_396">396</a></li>
+
+  <li>Centridermichthys,
+    <a href="#Page_477">477</a></li>
+
+  <li>Centrina,
+    <a href="#Page_331">331</a></li>
+
+  <li>Centriscus,
+    <a href="#Page_509">509</a></li>
+
+  <li>Centrolabrus,
+    <a href="#Page_528">528</a></li>
+
+  <li>Ceutrolepis,
+    <a href="#Page_370">370</a></li>
+
+  <li>Centrolophus,
+    <a href="#Page_452">452</a></li>
+
+  <li>Centromochlus,
+    <a href="#Page_572">572</a></li>
+
+  <li>Centronotus,
+    <a href="#Page_496">496</a></li>
+
+  <li>Centrophorus,
+    <a href="#Page_331">331</a></li>
+
+  <li>Centropogon,
+    <a href="#Page_417">417</a></li>
+
+  <li>Centropomus,
+    <a href="#Page_379">379</a></li>
+
+  <li>Ceutropristis,
+    <a href="#Page_380">380</a></li>
+
+  <li>Centroscyllium,
+    <a href="#Page_332">332</a></li>
+
+  <li>Centrum,
+    <a href="#Page_51">51</a></li>
+
+  <li>Cephalacanthus,
+    <a href="#Page_482">482</a></li>
+
+  <li>Cephalaspis,
+    <a href="#Page_353">353</a></li>
+
+  <li>Cephaloptera,
+    <a href="#Page_347">347</a></li>
+
+  <li>Cephenoplosus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Cepola,
+    <a href="#Page_490">490</a></li>
+
+  <li>Ceratias,
+    <a href="#Page_472">472</a></li>
+
+  <li>Ceratichthys,
+    <a href="#Page_596">596</a></li>
+
+  <li>Ceratobranchial,
+    <a href="#Page_58">58</a></li>
+
+  <li>Ceratodus,
+    <a href="#Page_357">357</a></li>
+
+  <li>Ceratohyal,
+    <a href="#Page_58">58</a></li>
+
+  <li>Ceratoptera,
+    <a href="#Page_347">347</a></li>
+
+  <li>Cerebellum,
+    <a href="#Page_97">97</a></li>
+
+  <li>Cestracion,
+    <a href="#Page_330">330</a></li>
+
+  <li>Cestraciontidæ,
+    <a href="#Page_328">328</a></li>
+
+  <li>Cetengraulis,
+    <a href="#Page_656">656</a></li>
+
+  <li>Cetopsis,
+    <a href="#Page_572">572</a></li>
+
+  <li>Chaca,
+    <a href="#Page_564">564</a></li>
+
+  <li>Chad,
+    <a href="#Page_408">408</a></li>
+
+  <li>Chænichthys,
+    <a href="#Page_466">466</a></li>
+
+  <li>Chætobranchus,
+    <a href="#Page_537">537</a></li>
+
+  <li>Chætodon,
+    <a href="#Page_398">398</a></li>
+
+  <li>Chætopterus,
+    <a href="#Page_390">390</a></li>
+
+  <li>Chætostomus,
+    <a href="#Page_576">576</a></li>
+
+  <li>Chalceus,
+    <a href="#Page_610">610</a></li>
+
+  <li>Chalcinopsis,
+    <a href="#Page_610">610</a></li>
+
+  <li>Chalcinus,
+    <a href="#Page_610">610</a></li>
+
+  <li>Champsodon,
+    <a href="#Page_464">464</a></li>
+
+  <li>Channa,
+    <a href="#Page_513">513</a></li>
+
+  <li>Chanodichthys,
+    <a href="#Page_604">604</a></li>
+
+  <li>Chanos,
+    <a href="#Page_662">662</a></li>
+
+  <li>Characinidæ,
+    <a href="#Page_606">606</a></li>
+
+  <li>Characodon,
+    <a href="#Page_615">615</a></li>
+
+  <li>Charr,
+    <a href="#Page_645">645</a></li>
+
+  <li>Chasmodes,
+    <a href="#Page_494">494</a></li>
+
+  <li>Chatoëssus,
+    <a href="#Page_657">657</a></li>
+
+  <li>Chauliodus,
+    <a href="#Page_628">628</a></li>
+
+  <li>Chaunax,
+    <a href="#Page_474">474</a></li>
+
+  <li>Cheilio,
+    <a href="#Page_530">530</a></li>
+
+  <li>Chela,
+    <a href="#Page_604">604</a></li>
+
+  <li>Chelmo,
+    <a href="#Page_399">399</a></li>
+
+  <li>Chiasmodus,
+    <a href="#Page_546">546</a></li>
+
+  <li>Chilian district,
+    <a href="#Page_288">288</a></li>
+
+  <li>Chilinus,
+    <a href="#Page_528">528</a></li>
+
+  <li>Chilobranchus,
+    <a href="#Page_669">669</a></li>
+
+  <li>Chilodactylus,
+    <a href="#Page_411">411</a></li>
+
+  <li>Chilodipterus,
+    <a href="#Page_395">395</a></li>
+
+  <li>Chilomycterus,
+    <a href="#Page_689">689</a></li>
+
+  <li>Chilorhinus,
+    <a href="#Page_674">674</a></li>
+
+  <li>Chiloscyllium,
+    <a href="#Page_326">326</a>,
+    <a href="#Page_327">327</a></li>
+
+  <li>Chimæra,
+    <a href="#Page_349">349</a></li>
+
+  <li>Chimæridæ,
+    <a href="#Page_348">348</a></li>
+
+  <li>Chimarrhichthys,
+    <a href="#Page_466">466</a></li>
+
+  <li>Chiracanthus,
+    <a href="#Page_355">355</a></li>
+
+  <li>Chirocentrites,
+    <a href="#Page_656">656</a></li>
+
+  <li>Chirocentrodon,
+    <a href="#Page_660">660</a></li>
+
+  <li>Chirocentrus,
+    <a href="#Page_663">663</a></li>
+
+  <li>Chirodon,
+    <a href="#Page_609">609</a></li>
+
+  <li>Chirodus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Chirolepis,
+    <a href="#Page_370">370</a></li>
+
+  <li>Chironemus,
+    <a href="#Page_411">411</a></li>
+
+  <li>Chirus,
+    <a href="#Page_491">491</a></li>
+
+  <li>Chlorophthalmus,
+    <a href="#Page_587">587</a></li>
+
+  <li>Chœrops,
+    <a href="#Page_530">530</a></li>
+
+  <li>Chologaster,
+    <a href="#Page_618">618</a></li>
+
+  <li>Chomatodus,
+    <a href="#Page_329">329</a></li>
+
+  <li>Chondropterygii,
+    <a href="#Page_313">313</a></li>
+
+  <li>Chondrostei,
+    <a href="#Page_360">360</a></li>
+
+  <li>Chondrosteus,
+    <a href="#Page_363">363</a></li>
+
+  <li>Chondrostoma,
+    <a href="#Page_600">600</a></li>
+
+  <li>Chorda dorsalis,
+    <a href="#Page_63">63</a></li>
+
+  <li>Chorinemus,
+    <a href="#Page_446">446</a></li>
+
+  <li>Chorismodactylus,
+    <a href="#Page_417">417</a></li>
+
+  <li>Chorisochismus,
+    <a href="#Page_512">512</a></li>
+
+  <li>Chromatophors,
+    <a href="#Page_183">183</a></li>
+
+  <li>Chromides,
+    <a href="#Page_534">534</a></li>
+
+  <li>Chromis,
+    <a href="#Page_535">535</a></li>
+
+  <li>Chrysichthys,
+    <a href="#Page_567">567</a></li>
+
+  <li>Chrysophrys,
+    <a href="#Page_409">409</a></li>
+
+  <li>Chub,
+    <a href="#Page_596">596</a>,
+    <a href="#Page_599">599</a>,
+    <a href="#Page_600">600</a></li>
+
+  <li>Cichla,
+    <a href="#Page_536">536</a></li>
+
+  <li>Cichlops,
+    <a href="#Page_466">466</a></li>
+
+  <li>Circulation, organs of,
+    <a href="#Page_150">150</a></li>
+
+  <li>Cirrhilabrus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Cirrhina,
+    <a href="#Page_596">596</a></li>
+
+  <li>Cirrhites,
+    <a href="#Page_411">411</a></li>
+
+  <li>Cirrhitidæ,
+    <a href="#Page_410">410</a></li>
+
+  <li>Cirrostomi,
+    <a href="#Page_696">696</a></li>
+
+  <li>Citharichthys,
+    <a href="#Page_556">556</a></li>
+
+  <li>Citharinus,
+    <a href="#Page_607">607</a></li>
+
+  <li>Citharus,
+    <a href="#Page_556">556</a></li>
+
+  <li>Cladacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Cladodus,
+    <a href="#Page_328">328</a></li>
+
+  <li>Clarias,
+    <a href="#Page_563">563</a></li>
+
+  <li>Clarotes,
+    <a href="#Page_567">567</a></li>
+
+  <li>Claspers,
+    <a href="#Page_167">167</a></li>
+
+  <li>Clavicula,
+    <a href="#Page_59">59</a>,
+    <a href="#Page_92">92</a></li>
+
+  <li>Clepticus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Climbing Perch,
+    <a href="#Page_516">516</a></li>
+
+  <li>Clinus,
+    <a href="#Page_495">495</a></li>
+
+  <li>Cloudy Bay cod,
+    <a href="#Page_549">549</a></li>
+
+  <li>Clupea,
+    <a href="#Page_658">658</a></li>
+
+  <li>Clupeichthys,
+    <a href="#Page_660">660</a></li>
+
+  <li>Clupeoides,
+    <a href="#Page_660">660</a></li>
+
+  <li>Cnidoglanis,
+    <a href="#Page_564">564</a></li>
+
+  <li>Coal-fish,
+    <a href="#Page_541">541</a></li>
+
+  <li>Cobitis,
+    <a href="#Page_605">605</a></li>
+
+  <li>Coccia,
+    <a href="#Page_628">628</a></li>
+
+  <li>Coccosteus,
+    <a href="#Page_351">351</a></li>
+
+  <li>Cochlognathus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Cochliodus,
+    <a href="#Page_329">329</a></li>
+
+  <li>Cock-and-hen Paddle,
+    <a href="#Page_484">484</a></li>
+
+  <li>Cod-fishes,
+    <a href="#Page_539">539</a></li>
+
+  <li>Cœcal stomach,
+    <a href="#Page_130">130</a></li>
+
+  <li>Coelacanthidæ,
+    <a href="#Page_365">365</a></li>
+
+  <li>Coelodus,
+    <a href="#Page_367">367</a></li>
+
+  <li>Coelogaster,
+    <a href="#Page_656">656</a></li>
+
+  <li>Coelonotus,
+    <a href="#Page_681">681</a></li>
+
+  <li>Coelorhynchus,
+    <a href="#Page_433">433</a></li>
+
+  <li>Coffer-fish,
+    <a href="#Page_686">686</a></li>
+
+  <li>Coilia,
+    <a href="#Page_657">657</a></li>
+
+  <li>Collichthys,
+    <a href="#Page_430">430</a></li>
+
+  <li>Commerson,
+    <a href="#Page_13">13</a></li>
+
+  <li>Conger,
+    <a href="#Page_673">673</a></li>
+
+  <li>Congrogadina,
+    <a href="#Page_550">550</a></li>
+
+  <li>Congromuræna,
+    <a href="#Page_674">674</a></li>
+
+  <li>Conodon,
+    <a href="#Page_386">386</a></li>
+
+  <li>Conodonts,
+    <a href="#Page_193">193</a></li>
+
+  <li>Conodus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Conorhynchus,
+    <a href="#Page_569">569</a></li>
+
+  <li>Conus arteriosus,
+    <a href="#Page_151">151</a></li>
+
+  <li>Cook,
+    <a href="#Page_527">527</a></li>
+
+  <li>Copidoglanis,
+    <a href="#Page_564">564</a></li>
+
+  <li>Coracoid,
+    <a href="#Page_59">59</a>,
+    <a href="#Page_92">92</a></li>
+
+  <li>Coral-fishes,
+    <a href="#Page_397">397</a>,
+    <a href="#Page_525">525</a></li>
+
+  <li>Corax,
+    <a href="#Page_317">317</a></li>
+
+  <li>Coregonus,
+    <a href="#Page_647">647</a></li>
+
+  <li>Coridodax,
+    <a href="#Page_533">533</a></li>
+
+  <li>Coris,
+    <a href="#Page_530">530</a></li>
+
+  <li>Cork-wing,
+    <a href="#Page_527">527</a></li>
+
+  <li>Cornide,
+    <a href="#Page_13">13</a></li>
+
+  <li>Corpora quadrigemina,
+    <a href="#Page_103">103</a></li>
+
+  <li>Corpora restiformia,
+    <a href="#Page_99">99</a></li>
+
+  <li>Corpora striata,
+    <a href="#Page_100">100</a></li>
+
+  <li>Corvina,
+    <a href="#Page_430">430</a></li>
+
+  <li>Corvo,
+    <a href="#Page_429">429</a></li>
+
+  <li>Corynopoma,
+    <a href="#Page_607">607</a></li>
+
+  <li>Coryphæna,
+    <a href="#Page_452">452</a></li>
+
+  <li>Coryphænoides,
+    <a href="#Page_552">552</a></li>
+
+  <li>Cosmolepis,
+    <a href="#Page_370">370</a></li>
+
+  <li>Cosmoptychius,
+    <a href="#Page_370">370</a></li>
+
+  <li>Cossyphus,
+    <a href="#Page_528">528</a></li>
+
+  <li>Costa,
+    <a href="#Page_28">28</a></li>
+
+  <li>Cottoperca,
+    <a href="#Page_466">466</a></li>
+
+  <li>Cottus,
+    <a href="#Page_476">476</a></li>
+
+  <li>Cotylis,
+    <a href="#Page_512">512</a></li>
+
+  <li>Couch,
+    <a href="#Page_27">27</a></li>
+
+  <li>Couchia,
+    <a href="#Page_544">544</a></li>
+
+  <li>Craig-fluke,
+    <a href="#Page_557">557</a></li>
+
+  <li>Creagrutus,
+    <a href="#Page_610">610</a></li>
+
+  <li>Cremnobates,
+    <a href="#Page_495">495</a></li>
+
+  <li>Crenicichla,
+    <a href="#Page_537">537</a></li>
+
+  <li>Crenidens,
+    <a href="#Page_406">406</a></li>
+
+  <li>Crenilabrus,
+    <a href="#Page_527">527</a></li>
+
+  <li>Crenuchus,
+    <a href="#Page_612">612</a></li>
+
+  <li>Crepidogaster,
+    <a href="#Page_513">513</a></li>
+
+  <li>Cretaceous fishes,
+    <a href="#Page_199">199</a></li>
+
+  <li>Cricacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Cristiceps,
+    <a href="#Page_495">495</a></li>
+
+  <li>Crossochilus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Crossognathus,
+    <a href="#Page_656">656</a></li>
+
+  <li>Crossorhinus,
+    <a href="#Page_328">328</a></li>
+
+  <li>Crossostoma,
+    <a href="#Page_604">604</a></li>
+
+  <li>Crucian carp,
+    <a href="#Page_591">591</a></li>
+
+  <li>Crura cerebri,
+    <a href="#Page_98">98</a></li>
+
+  <li>Cryptacanthodes,
+    <a href="#Page_496">496</a></li>
+
+  <li>Cryptopterus,
+    <a href="#Page_566">566</a></li>
+
+  <li>Ctenododipteridæ,
+    <a href="#Page_359">359</a></li>
+
+  <li>Ctenodus,
+    <a href="#Page_359">359</a></li>
+
+  <li>Ctenoid scales,
+    <a href="#Page_46">46</a></li>
+
+  <li>Ctenolabrus,
+    <a href="#Page_527">527</a></li>
+
+  <li>Ctenopharyngodon,
+    <a href="#Page_601">601</a></li>
+
+  <li>Ctenopoma,
+    <a href="#Page_516">516</a></li>
+
+  <li>Ctenoptychius,
+    <a href="#Page_329">329</a></li>
+
+  <li>Cubiceps,
+    <a href="#Page_456">456</a></li>
+
+  <li>Culter,
+    <a href="#Page_604">604</a></li>
+
+  <li>Curimatus,
+    <a href="#Page_607">607</a></li>
+
+  <li>Cut-lips,
+    <a href="#Page_596">596</a></li>
+
+  <li>Cuvier,
+    <a href="#Page_17">17</a></li>
+
+  <li>Cyathaspis,
+    <a href="#Page_354">354</a></li>
+
+  <li>Cybium,
+    <a href="#Page_459">459</a></li>
+
+  <li>Cyclobatis,
+    <a href="#Page_340">340</a></li>
+
+  <li>Cycloid scales,
+    <a href="#Page_46">46</a></li>
+
+  <li>Cyclopoma,
+    <a href="#Page_375">375</a></li>
+
+  <li>Cyclopterus,
+    <a href="#Page_484">484</a></li>
+
+  <li>Cycloptychius,
+    <a href="#Page_370">370</a></li>
+
+  <li>Cyclostomata,
+    <a href="#Page_691">691</a></li>
+
+  <li>Cyclurus,
+    <a href="#Page_588">588</a></li>
+
+  <li>Cyema,
+    <a href="#Page_670">670</a></li>
+
+  <li>Cymolutes,
+    <a href="#Page_530">530</a></li>
+
+  <li>Cynodon,
+    <a href="#Page_611">611</a></li>
+
+  <li>Cynoglossus,
+    <a href="#Page_558">558</a></li>
+
+  <li>Cynolebias,
+    <a href="#Page_615">615</a></li>
+
+  <li>Cyprinidæ,
+    <a href="#Page_587">587</a></li>
+
+  <li>Cyprinion,
+    <a href="#Page_598">598</a></li>
+
+  <li>Cyprinodon,
+    <a href="#Page_614">614</a></li>
+
+  <li>Cyprinoid division,
+    <a href="#Page_217">217</a></li>
+
+  <li>Cyprinus,
+    <a href="#Page_589">589</a></li>
+
+  <li>Cyttidæ,
+    <a href="#Page_450">450</a></li>
+
+  <li>Cyttus,
+    <a href="#Page_451">451</a></li>
+</ul>
+
+<ul>
+  <li>Dab,
+    <a href="#Page_557">557</a></li>
+
+  <li>Dace,
+    <a href="#Page_599">599</a>,
+    <a href="#Page_600">600</a></li>
+
+  <li>Dactylopterus,
+    <a href="#Page_481">481</a></li>
+
+  <li>Dactyloscopus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Dangila,
+    <a href="#Page_596">596</a></li>
+
+  <li>Danio,
+    <a href="#Page_602">602</a></li>
+
+  <li>Dascyllus,
+    <a href="#Page_525">525</a></li>
+
+  <li>Datnioides,
+    <a href="#Page_397">397</a></li>
+
+  <li>Daurade,
+    <a href="#Page_409">409</a></li>
+
+  <li>Day,
+    <a href="#Page_30">30</a></li>
+
+  <li>Deal-fish,
+    <a href="#Page_522">522</a></li>
+
+  <li>Decodon,
+    <a href="#Page_530">530</a></li>
+
+  <li>Deep-sea fishes,
+    <a href="#Page_296">296</a></li>
+
+  <li>Dekay,
+    <a href="#Page_29">29</a></li>
+
+  <li>Dendrodus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Dentary,
+    <a href="#Page_54">54</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Dentex,
+    <a href="#Page_389">389</a></li>
+
+  <li>Dercetis,
+    <a href="#Page_666">666</a></li>
+
+  <li>Dermal spines,
+    <a href="#Page_53">53</a></li>
+
+  <li>Dermoskeleton,
+    <a href="#Page_85">85</a></li>
+
+  <li>Devil-fishes,
+    <a href="#Page_344">344</a></li>
+
+  <li>Devonian fishes,
+    <a href="#Page_193">193</a>,
+    <a href="#Page_194">194</a></li>
+
+  <li>Diagramma,
+    <a href="#Page_386">386</a></li>
+
+  <li>Diana,
+    <a href="#Page_455">455</a></li>
+
+  <li>Dibranchus,
+    <a href="#Page_475">475</a></li>
+
+  <li>Dicerobatis,
+    <a href="#Page_347">347</a></li>
+
+  <li>Dicotylichthys,
+    <a href="#Page_689">689</a></li>
+
+  <li>Dicrotus,
+    <a href="#Page_437">437</a></li>
+
+  <li>Dictyosoma,
+    <a href="#Page_498">498</a></li>
+
+  <li>Didymaspis,
+    <a href="#Page_354">354</a></li>
+
+  <li>Digestion, organs of,
+    <a href="#Page_121">121</a></li>
+
+  <li>Dimeracanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Dinematichthys,
+    <a href="#Page_549">549</a></li>
+
+  <li>Dinichthys,
+    <a href="#Page_352">352</a></li>
+
+  <li>Diodon,
+    <a href="#Page_689">689</a></li>
+
+  <li>Dioecious,
+    <a href="#Page_157">157</a></li>
+
+  <li>Diplocrepis,
+    <a href="#Page_513">513</a></li>
+
+  <li>Diplomystax,
+    <a href="#Page_569">569</a></li>
+
+  <li>Diplophos,
+    <a href="#Page_629">629</a></li>
+
+  <li>Diploprion,
+    <a href="#Page_383">383</a></li>
+
+  <li>Diplopterus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Dipnoi,
+    <a href="#Page_355">355</a></li>
+
+  <li>Dipterodon,
+    <a href="#Page_406">406</a></li>
+
+  <li>Dipterus,
+    <a href="#Page_359">359</a></li>
+
+  <li>Diptychus,
+    <a href="#Page_595">595</a></li>
+
+  <li>Diretmus,
+    <a href="#Page_449">449</a></li>
+
+  <li>Discoboli,
+    <a href="#Page_483">483</a></li>
+
+  <li>Discognathus,
+    <a href="#Page_593">593</a></li>
+
+  <li>Discopyge,
+    <a href="#Page_340">340</a></li>
+
+  <li>Distichodus,
+    <a href="#Page_612">612</a></li>
+
+  <li>Ditrema,
+    <a href="#Page_534">534</a></li>
+
+  <li>Dog-fishes,
+    <a href="#Page_325">325</a>,
+    <a href="#Page_619">619</a></li>
+
+  <li>Doliichthys,
+    <a href="#Page_487">487</a></li>
+
+  <li>Dolphins,
+    <a href="#Page_453">453</a></li>
+
+  <li>Domesticated fishes,
+    <a href="#Page_185">185</a></li>
+
+  <li>Domine,
+    <a href="#Page_436">436</a></li>
+
+  <li>Donovan,
+    <a href="#Page_17">17</a></li>
+
+  <li>Doras,
+    <a href="#Page_572">572</a></li>
+
+  <li>Doratonotus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Dorsal fin,
+    <a href="#Page_40">40</a></li>
+
+  <li>Dorsch,
+    <a href="#Page_540">540</a></li>
+
+  <li>Dory,
+    <a href="#Page_450">450</a></li>
+
+  <li>Doryichthys,
+    <a href="#Page_681">681</a></li>
+
+  <li>Doydixodon,
+    <a href="#Page_406">406</a></li>
+
+  <li>Dragonet,
+    <a href="#Page_489">489</a></li>
+
+  <li>Drepane,
+    <a href="#Page_402">402</a></li>
+
+  <li>Drepanephorus,
+    <a href="#Page_331">331</a></li>
+
+  <li>Drum,
+    <a href="#Page_427">427</a></li>
+
+  <li>Ductor,
+    <a href="#Page_442">442</a></li>
+
+  <li>Ductus choledochus,
+    <a href="#Page_133">133</a></li>
+
+  <li>Ductus cysticus,
+    <a href="#Page_133">133</a></li>
+
+  <li>Duhamel,
+    <a href="#Page_13">13</a></li>
+
+  <li>Dules,
+    <a href="#Page_384">384</a></li>
+
+  <li>Duméril,
+    <a href="#Page_33">33</a></li>
+
+  <li>Dussumieria,
+    <a href="#Page_662">662</a></li>
+
+  <li>Duverney,
+    <a href="#Page_7">7</a></li>
+
+  <li>Duymæria,
+    <a href="#Page_530">530</a></li>
+</ul>
+
+<ul>
+  <li>Eagle-Rays,
+    <a href="#Page_344">344</a></li>
+
+  <li>Ear,
+    <a href="#Page_116">116</a></li>
+
+  <li>Echeneis,
+    <a href="#Page_460">460</a></li>
+
+  <li>Echinorhinus,
+    <a href="#Page_333">333</a></li>
+
+  <li>Echiostoma,
+    <a href="#Page_629">629</a></li>
+
+  <li>Ectopterygoid,
+    <a href="#Page_90">90</a></li>
+
+  <li>Edaphodon,
+    <a href="#Page_349">349</a></li>
+
+  <li>Eel,
+    <a href="#Page_671">671</a></li>
+
+  <li>Eel-pout,
+    <a href="#Page_544">544</a></li>
+
+  <li>Egertonia,
+    <a href="#Page_526">526</a></li>
+
+  <li>Elacate,
+    <a href="#Page_460">460</a></li>
+
+  <li>Elasmodus,
+    <a href="#Page_349">349</a></li>
+
+  <li>Elasmognathus,
+    <a href="#Page_349">349</a></li>
+
+  <li>Electric Eel,
+    <a href="#Page_667">667</a></li>
+
+  <li>Electric organs,
+    <a href="#Page_94">94</a></li>
+
+  <li>Electric Rays,
+    <a href="#Page_339">339</a></li>
+
+  <li>Electric Sheath-fish,
+    <a href="#Page_574">574</a></li>
+
+  <li>Eleotris,
+    <a href="#Page_488">488</a></li>
+
+  <li>Elonichthys,
+    <a href="#Page_370">370</a></li>
+
+  <li>Elopichthys,
+    <a href="#Page_604">604</a></li>
+
+  <li>Elops,
+    <a href="#Page_661">661</a></li>
+
+  <li>Embiotocidæ,
+    <a href="#Page_533">533</a></li>
+
+  <li>Encheliophis,
+    <a href="#Page_549">549</a></li>
+
+  <li>Enchelycore,
+    <a href="#Page_677">677</a></li>
+
+  <li>Enchodus,
+    <a href="#Page_433">433</a></li>
+
+  <li>Endoskeleton,
+    <a href="#Page_85">85</a></li>
+
+  <li>Engraulis,
+    <a href="#Page_656">656</a></li>
+
+  <li>Enneodon,
+    <a href="#Page_687">687</a></li>
+
+  <li>Enoplosus,
+    <a href="#Page_380">380</a></li>
+
+  <li>Entopterygoid,
+    <a href="#Page_55">55</a>,
+    <a href="#Page_90">90</a></li>
+
+  <li>Epalzeorhynchus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Ephippus,
+    <a href="#Page_402">402</a></li>
+
+  <li>Epibranchial,
+    <a href="#Page_59">59</a></li>
+
+  <li>Epibulus,
+    <a href="#Page_528">528</a></li>
+
+  <li>Epicoracoid,
+    <a href="#Page_59">59</a></li>
+
+  <li>Epididymis,
+    <a href="#Page_167">167</a></li>
+
+  <li>Epigionichthys,
+    <a href="#Page_696">696</a></li>
+
+  <li>Epihyal,
+    <a href="#Page_58">58</a></li>
+
+  <li>Epinnula,
+    <a href="#Page_436">436</a></li>
+
+  <li>Epioticum,
+    <a href="#Page_88">88</a></li>
+
+  <li>Epiphysis,
+    <a href="#Page_98">98</a></li>
+
+  <li>Epitympanic,
+    <a href="#Page_55">55</a></li>
+
+  <li>Equatorial zone,
+    <a href="#Page_218">218</a>,
+    <a href="#Page_272">272</a></li>
+
+  <li>Eques,
+    <a href="#Page_431">431</a></li>
+
+  <li>Equula,
+    <a href="#Page_449">449</a></li>
+
+  <li>Eremophilus,
+    <a href="#Page_581">581</a></li>
+
+  <li>Erethistes,
+    <a href="#Page_580">580</a></li>
+
+  <li>Ericymba,
+    <a href="#Page_596">596</a></li>
+
+  <li>Erythrichthys,
+    <a href="#Page_391">391</a></li>
+
+  <li>Erythrinus,
+    <a href="#Page_607">607</a></li>
+
+  <li>Escholar,
+    <a href="#Page_437">437</a></li>
+
+  <li>Esox,
+    <a href="#Page_624">624</a></li>
+
+  <li>Etelis,
+    <a href="#Page_397">397</a></li>
+
+  <li>Etheostomatidæ,
+    <a href="#Page_379">379</a></li>
+
+  <li>Ethmoid,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Etroplus,
+    <a href="#Page_534">534</a></li>
+
+  <li>Etrumeus,
+    <a href="#Page_662">662</a></li>
+
+  <li>Euanemus,
+    <a href="#Page_572">572</a></li>
+
+  <li>Euctenogobius,
+    <a href="#Page_487">487</a></li>
+
+  <li>Euglyptosternum,
+    <a href="#Page_571">571</a></li>
+
+  <li>Eugnathus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Eulachon,
+    <a href="#Page_647">647</a></li>
+
+  <li>Eulepidotus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Euoxymetopon,
+    <a href="#Page_434">434</a></li>
+
+  <li>Euprotomicrus,
+    <a href="#Page_334">334</a></li>
+
+  <li>Europo-Asiatic region,
+    <a href="#Page_243">243</a></li>
+
+  <li>Eurynotus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Eurypholis,
+    <a href="#Page_666">666</a></li>
+
+  <li>Eurysomus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Eustira,
+    <a href="#Page_604">604</a></li>
+
+  <li>Eutropiichthys,
+    <a href="#Page_566">566</a></li>
+
+  <li>Eutropius,
+    <a href="#Page_566">566</a></li>
+
+  <li>Evorthodus,
+    <a href="#Page_487">487</a></li>
+
+  <li>Exoccipital,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_87">87</a></li>
+
+  <li>Exocoetus,
+    <a href="#Page_621">621</a></li>
+
+  <li>Exoglossum,
+    <a href="#Page_596">596</a></li>
+
+  <li>Exostoma,
+    <a href="#Page_580">580</a></li>
+
+  <li>Eye,
+    <a href="#Page_36">36</a>,
+    <a href="#Page_111">111</a></li>
+</ul>
+
+
+<ul>
+  <li>Fabricius,
+    <a href="#Page_13">13</a></li>
+
+  <li>Fall-fish,
+    <a href="#Page_600">600</a></li>
+
+  <li>Fierasfer,
+    <a href="#Page_549">549</a></li>
+
+  <li>Fighting-fish,
+    <a href="#Page_519">519</a></li>
+
+  <li>File-fishes,
+    <a href="#Page_684">684</a></li>
+
+  <li>Fins,
+    <a href="#Page_40">40</a></li>
+
+  <li>Fishing-Frog,
+    <a href="#Page_470">470</a></li>
+
+  <li>Fistularia,
+    <a href="#Page_507">507</a>,
+    <a href="#Page_508">508</a></li>
+
+  <li>Fitzroyia,
+    <a href="#Page_615">615</a></li>
+
+  <li>Flat-fishes,
+    <a href="#Page_553">553</a></li>
+
+  <li>Flounder,
+    <a href="#Page_557">557</a></li>
+
+  <li>Flute-mouth,
+    <a href="#Page_507">507</a></li>
+
+  <li>Flying-fish,
+    <a href="#Page_621">621</a></li>
+
+  <li>Flying Gurnard,
+    <a href="#Page_482">482</a></li>
+
+  <li>Forskal,
+    <a href="#Page_13">13</a></li>
+
+  <li>Forster,
+    <a href="#Page_13">13</a></li>
+
+  <li>Freshwater-fishes,
+    <a href="#Page_208">208</a></li>
+
+  <li>Freshwater-Herring,
+    <a href="#Page_645">645</a></li>
+
+  <li>Fries and Ekström,
+    <a href="#Page_27">27</a></li>
+
+  <li>Frog-fish,
+    <a href="#Page_470">470</a></li>
+
+  <li>Frontal bone,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Frost-fish,
+    <a href="#Page_436">436</a></li>
+
+  <li>Fuegian sub-region,
+    <a href="#Page_248">248</a></li>
+
+  <li>Fundulus,
+    <a href="#Page_615">615</a></li>
+</ul>
+
+<ul>
+  <li>Gadiculus,
+    <a href="#Page_541">541</a></li>
+
+  <li>Gadidæ,
+    <a href="#Page_539">539</a></li>
+
+  <li>Gadopsis,
+    <a href="#Page_537">537</a></li>
+
+  <li>Gadus,
+    <a href="#Page_539">539</a></li>
+
+  <li>Galapagoes district,
+    <a href="#Page_280">280</a></li>
+
+  <li>Galaxias,
+    <a href="#Page_624">624</a></li>
+
+  <li>Galeichthys,
+    <a href="#Page_569">569</a></li>
+
+  <li>Galeocerdo,
+    <a href="#Page_317">317</a></li>
+
+  <li>Galeoides,
+    <a href="#Page_425">425</a></li>
+
+  <li>Galeus,
+    <a href="#Page_318">318</a></li>
+
+  <li>Gallo,
+    <a href="#Page_451">451</a></li>
+
+  <li>Gambusia,
+    <a href="#Page_616">616</a></li>
+
+  <li>Ganodus,
+    <a href="#Page_349">349</a></li>
+
+  <li>Ganoidei,
+    <a href="#Page_350">350</a></li>
+
+  <li>Ganoid scales,
+    <a href="#Page_47">47</a></li>
+
+  <li>Gar-pike,
+    <a href="#Page_367">367</a>,
+    <a href="#Page_620">620</a></li>
+
+  <li>Gaspereau,
+    <a href="#Page_659">659</a></li>
+
+  <li>Gastrochisma,
+    <a href="#Page_455">455</a></li>
+
+  <li>Gastrocnemus,
+    <a href="#Page_452">452</a></li>
+
+  <li>Gastromyzon,
+    <a href="#Page_604">604</a></li>
+
+  <li>Gastropelecus,
+    <a href="#Page_610">610</a></li>
+
+  <li>Gastrosteus,
+    <a href="#Page_505">505</a></li>
+
+  <li>Gastrotokeus,
+    <a href="#Page_682">682</a></li>
+
+  <li>Gazza,
+    <a href="#Page_450">450</a></li>
+
+  <li>Gegenbaur,
+    <a href="#Page_32">32</a></li>
+
+  <li>Gempylus,
+    <a href="#Page_437">437</a></li>
+
+  <li>Genidens,
+    <a href="#Page_569">569</a></li>
+
+  <li>Genyoroge,
+    <a href="#Page_384">384</a></li>
+
+  <li>Genypterus,
+    <a href="#Page_549">549</a></li>
+
+  <li>Geoffroy,
+    <a href="#Page_33">33</a></li>
+
+  <li>Geophagus,
+    <a href="#Page_537">537</a></li>
+
+  <li>Geotria,
+    <a href="#Page_693">693</a></li>
+
+  <li>Gerres,
+    <a href="#Page_388">388</a></li>
+
+  <li>Gillaroo,
+    <a href="#Page_645">645</a></li>
+
+  <li>Gill-cover,
+    <a href="#Page_38">38</a></li>
+
+  <li>Gill-opening,
+    <a href="#Page_38">38</a></li>
+
+  <li>Gill-rakers,
+    <a href="#Page_59">59</a>,
+    <a href="#Page_139">139</a></li>
+
+  <li>Gills,
+    <a href="#Page_136">136</a></li>
+
+  <li>Gilthead,
+    <a href="#Page_409">409</a></li>
+
+  <li>Ginglymostoma,
+    <a href="#Page_326">326</a></li>
+
+  <li>Girardinus,
+    <a href="#Page_618">618</a></li>
+
+  <li>Girella,
+    <a href="#Page_406">406</a></li>
+
+  <li>Glanidium,
+    <a href="#Page_572">572</a></li>
+
+  <li>Glanis,
+    <a href="#Page_566">566</a></li>
+
+  <li>Glaucosoma,
+    <a href="#Page_384">384</a></li>
+
+  <li>Globe-fish,
+    <a href="#Page_687">687</a></li>
+
+  <li>Glossohyal,
+    <a href="#Page_58">58</a></li>
+
+  <li>Glottis,
+    <a href="#Page_149">149</a></li>
+
+  <li>Glut,
+    <a href="#Page_673">673</a></li>
+
+  <li>Glutinous hag,
+    <a href="#Page_694">694</a></li>
+
+  <li>Glyphidodon,
+    <a href="#Page_525">525</a></li>
+
+  <li>Glyptauchen,
+    <a href="#Page_415">415</a></li>
+
+  <li>Glyptolæmus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Glyptolepis,
+    <a href="#Page_365">365</a></li>
+
+  <li>Glyptopomus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Glyptosternum,
+    <a href="#Page_572">572</a></li>
+
+  <li>Gmelin,
+    <a href="#Page_13">13</a></li>
+
+  <li>Gobiesocidæ,
+    <a href="#Page_510">510</a></li>
+
+  <li>Gobiesox,
+    <a href="#Page_513">513</a></li>
+
+  <li>Gobio,
+    <a href="#Page_595">595</a></li>
+
+  <li>Gobiodon,
+    <a href="#Page_487">487</a></li>
+
+  <li>Gobiosoma,
+    <a href="#Page_487">487</a></li>
+
+  <li>Gobius,
+    <a href="#Page_486">486</a></li>
+
+  <li>Goby,
+    <a href="#Page_486">486</a></li>
+
+  <li>Gold-fish,
+    <a href="#Page_591">591</a></li>
+
+  <li>Gold-Sinny,
+    <a href="#Page_527">527</a></li>
+
+  <li>Gomphodus,
+    <a href="#Page_319">319</a></li>
+
+  <li>Gomphosus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Gonatodus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Goniognathus,
+    <a href="#Page_452">452</a></li>
+
+  <li>Gonorhynchus,
+    <a href="#Page_652">652</a></li>
+
+  <li>Gonostoma,
+    <a href="#Page_629">629</a></li>
+
+  <li>Gourami,
+    <a href="#Page_517">517</a></li>
+
+  <li>Grammistes,
+    <a href="#Page_382">382</a></li>
+
+  <li>Granular teeth,
+    <a href="#Page_126">126</a></li>
+
+  <li>Graphiurus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Grayling,
+    <a href="#Page_649">649</a></li>
+
+  <li>Greenland Shark,
+    <a href="#Page_333">333</a></li>
+
+  <li>Grey Mullet,
+    <a href="#Page_501">501</a></li>
+
+  <li>Grig,
+    <a href="#Page_673">673</a></li>
+
+  <li>Gronow,
+    <a href="#Page_12">12</a></li>
+
+  <li>Growler,
+    <a href="#Page_393">393</a></li>
+
+  <li>Growth of Fishes,
+    <a href="#Page_170">170</a></li>
+
+  <li>Grystes,
+    <a href="#Page_392">392</a></li>
+
+  <li>Gudgeon,
+    <a href="#Page_596">596</a></li>
+
+  <li>Gular plates,
+    <a href="#Page_80">80</a></li>
+
+  <li>Güldenstedt,
+    <a href="#Page_13">13</a></li>
+
+  <li>Gunellichthys,
+    <a href="#Page_498">498</a></li>
+
+  <li>Gunnel-fish,
+    <a href="#Page_496">496</a></li>
+
+  <li>Günther,
+    <a href="#Page_27">27</a>,
+    <a href="#Page_30">30</a></li>
+
+  <li>Gurnard,
+    <a href="#Page_479">479</a></li>
+
+  <li>Gwyniad,
+    <a href="#Page_649">649</a></li>
+
+  <li>Gymnachirus,
+    <a href="#Page_558">558</a></li>
+
+  <li>Gymnarchus,
+    <a href="#Page_626">626</a></li>
+
+  <li>Gymnelis,
+    <a href="#Page_538">538</a></li>
+
+  <li>Gymnocrotaphus,
+    <a href="#Page_406">406</a></li>
+
+  <li>Gymnocypris,
+    <a href="#Page_595">595</a></li>
+
+  <li>Gymnomuræna,
+    <a href="#Page_677">677</a></li>
+
+  <li>Gynmoscopelus,
+    <a href="#Page_585">585</a></li>
+
+  <li>Gymnotus,
+    <a href="#Page_667">667</a></li>
+
+  <li>Gyracanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Gyrodus,
+    <a href="#Page_367">367</a></li>
+
+  <li>Gyropristis,
+    <a href="#Page_314">314</a></li>
+
+  <li>Gyroptychius,
+    <a href="#Page_365">365</a></li>
+</ul>
+
+<ul>
+  <li>Haddock,
+    <a href="#Page_540">540</a></li>
+
+  <li>Hadot,
+    <a href="#Page_540">540</a></li>
+
+  <li>Hæmal arches,
+    <a href="#Page_86">86</a></li>
+
+  <li>Hæmal spine,
+    <a href="#Page_52">52</a></li>
+
+  <li>Hæmapophyses,
+    <a href="#Page_51">51</a></li>
+
+  <li>Hæmulon,
+    <a href="#Page_386">386</a></li>
+
+  <li>Hag-fish,
+    <a href="#Page_694">694</a></li>
+
+  <li>Hair-tail,
+    <a href="#Page_436">436</a></li>
+
+  <li>Hake,
+    <a href="#Page_542">542</a></li>
+
+  <li>Halargyreus,
+    <a href="#Page_541">541</a></li>
+
+  <li>Halec,
+    <a href="#Page_656">656</a></li>
+
+  <li>Halecidæ,
+    <a href="#Page_656">656</a></li>
+
+  <li>Half-beak,
+    <a href="#Page_621">621</a></li>
+
+  <li>Halidesmus,
+    <a href="#Page_549">549</a></li>
+
+  <li>Halieutæa,
+    <a href="#Page_475">475</a></li>
+
+  <li>Halieutichthys,
+    <a href="#Page_475">475</a></li>
+
+  <li>Haliophis,
+    <a href="#Page_550">550</a></li>
+
+  <li>Haller,
+    <a href="#Page_16">16</a></li>
+
+  <li>Haloporphyrus,
+    <a href="#Page_543">543</a></li>
+
+  <li>Halosauridæ,
+    <a href="#Page_665">665</a></li>
+
+  <li>Hamilton,
+    <a href="#Page_17">17</a></li>
+
+  <li>Hammerhead,
+    <a href="#Page_318">318</a></li>
+
+  <li>Hapalogenys,
+    <a href="#Page_386">386</a></li>
+
+  <li>Haplochilus,
+    <a href="#Page_615">615</a></li>
+
+  <li>Haplochiton,
+    <a href="#Page_651">651</a></li>
+
+  <li>Haplodactylina,
+    <a href="#Page_406">406</a></li>
+
+  <li>Hapuku,
+    <a href="#Page_392">392</a></li>
+
+  <li>Harpagifer,
+    <a href="#Page_467">467</a></li>
+
+  <li>Harpodon,
+    <a href="#Page_583">583</a></li>
+
+  <li>Harttia,
+    <a href="#Page_580">580</a></li>
+
+  <li>Hasse,
+    <a href="#Page_32">32</a></li>
+
+  <li>Hasselquist,
+    <a href="#Page_13">13</a></li>
+
+  <li>Hausen,
+    <a href="#Page_361">361</a></li>
+
+  <li>Head,
+    <a href="#Page_36">36</a></li>
+
+  <li>Heart,
+    <a href="#Page_150">150</a></li>
+
+  <li>Heckel,
+    <a href="#Page_28">28</a></li>
+
+  <li>Hector,
+    <a href="#Page_32">32</a></li>
+
+  <li>Heliastes,
+    <a href="#Page_525">525</a></li>
+
+  <li>Helicophagus,
+    <a href="#Page_566">566</a></li>
+
+  <li>Heliodus,
+    <a href="#Page_359">359</a></li>
+
+  <li>Helmichthys,
+    <a href="#Page_180">180</a></li>
+
+  <li>Helogenes,
+    <a href="#Page_567">567</a></li>
+
+  <li>Helotes,
+    <a href="#Page_385">385</a></li>
+
+  <li>Hemerocœtes,
+    <a href="#Page_491">491</a></li>
+
+  <li>Hemichromis,
+    <a href="#Page_535">535</a></li>
+
+  <li>Hemiculter,
+    <a href="#Page_604">604</a></li>
+
+  <li>Hemigaleus,
+    <a href="#Page_319">319</a></li>
+
+  <li>Hemigymnus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Hemilepidotus,
+    <a href="#Page_480">480</a></li>
+
+  <li>Hemiodus,
+    <a href="#Page_607">607</a></li>
+
+  <li>Hemipimelodus,
+    <a href="#Page_569">569</a></li>
+
+  <li>Hemipristis,
+    <a href="#Page_317">317</a></li>
+
+  <li>Hemirhamphus,
+    <a href="#Page_621">621</a></li>
+
+  <li>Hemirhombus,
+    <a href="#Page_556">556</a></li>
+
+  <li>Hemirhynchus,
+    <a href="#Page_437">437</a></li>
+
+  <li>Hemisaurida,
+    <a href="#Page_582">582</a></li>
+
+  <li>Hemisilurus,
+    <a href="#Page_566">566</a></li>
+
+  <li>Hemisorubim,
+    <a href="#Page_568">568</a></li>
+
+  <li>Hemithyrsites,
+    <a href="#Page_434">434</a></li>
+
+  <li>Hemitrichas,
+    <a href="#Page_656">656</a></li>
+
+  <li>Hemitripterus,
+    <a href="#Page_417">417</a></li>
+
+  <li>Heniochus,
+    <a href="#Page_399">399</a></li>
+
+  <li>Heptanchus,
+    <a href="#Page_325">325</a></li>
+
+  <li>Heptapterus,
+    <a href="#Page_581">581</a></li>
+
+  <li>Hermaphroditism,
+    <a href="#Page_157">157</a></li>
+
+  <li>Heros,
+    <a href="#Page_536">536</a></li>
+
+  <li>Herring,
+    <a href="#Page_658">658</a></li>
+
+  <li>Heteracanth,
+    <a href="#Page_41">41</a></li>
+
+  <li>Heterobranchus,
+    <a href="#Page_563">563</a></li>
+
+  <li>Heterocercy,
+    <a href="#Page_80">80</a></li>
+
+  <li>Heteroconger,
+    <a href="#Page_674">674</a></li>
+
+  <li>Heterognathodon,
+    <a href="#Page_389">389</a></li>
+
+  <li>Heterolepidotidæ,
+    <a href="#Page_491">491</a></li>
+
+  <li>Heteropygii,
+    <a href="#Page_618">618</a></li>
+
+  <li>Heterostichus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Heterotis,
+    <a href="#Page_655">655</a></li>
+
+  <li>Hexanchus,
+    <a href="#Page_325">325</a></li>
+
+  <li>Hexapsephus,
+    <a href="#Page_588">588</a></li>
+
+  <li>Himantolophus,
+    <a href="#Page_472">472</a></li>
+
+  <li>Hippocampus,
+    <a href="#Page_683">683</a></li>
+
+  <li>Hippoglossoides,
+    <a href="#Page_555">555</a></li>
+
+  <li>Hippoglossus,
+    <a href="#Page_555">555</a></li>
+
+  <li>Histiophorus,
+    <a href="#Page_431">431</a></li>
+
+  <li>Histiopterus,
+    <a href="#Page_387">387</a></li>
+
+  <li>Holacanthus,
+    <a href="#Page_400">400</a></li>
+
+  <li>Holibut,
+    <a href="#Page_555">555</a></li>
+
+  <li>Hollardia,
+    <a href="#Page_684">684</a></li>
+
+  <li>Holocentrum,
+    <a href="#Page_423">423</a></li>
+
+  <li>Holocephala,
+    <a href="#Page_348">348</a></li>
+
+  <li>Holophagus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Holoptychidæ,
+    <a href="#Page_365">365</a></li>
+
+  <li>Holosteus,
+    <a href="#Page_619">619</a></li>
+
+  <li>Homacanth,
+    <a href="#Page_41">41</a></li>
+
+  <li>Homaloptera,
+    <a href="#Page_604">604</a></li>
+
+  <li>Hombron et Jacquinot,
+    <a href="#Page_27">27</a></li>
+
+  <li>Homelyn Ray,
+    <a href="#Page_341">341</a></li>
+
+  <li>Homocanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Homocercy,
+    <a href="#Page_83">83</a></li>
+
+  <li>Homoeolepis,
+    <a href="#Page_366">366</a></li>
+
+  <li>Homonotus,
+    <a href="#Page_421">421</a></li>
+
+  <li>Hopladelus,
+    <a href="#Page_568">568</a></li>
+
+  <li>Hoplichthys,
+    <a href="#Page_478">478</a></li>
+
+  <li>Hoplognathus,
+    <a href="#Page_410">410</a></li>
+
+  <li>Hoplopleuridæ,
+    <a href="#Page_665">665</a></li>
+
+  <li>Hoplopteryx,
+    <a href="#Page_421">421</a></li>
+
+  <li>Hoplopygus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Hoplostethus,
+    <a href="#Page_421">421</a></li>
+
+  <li>Hoplunnis,
+    <a href="#Page_674">674</a></li>
+
+  <li>Horse-mackerel,
+    <a href="#Page_442">442</a></li>
+
+  <li>Hounds,
+    <a href="#Page_319">319</a></li>
+
+  <li>Huchen,
+    <a href="#Page_645">645</a></li>
+
+  <li>Humeral arch,
+    <a href="#Page_59">59</a></li>
+
+  <li>Hunds-fish,
+    <a href="#Page_619">619</a></li>
+
+  <li>Hunter,
+    <a href="#Page_16">16</a></li>
+
+  <li>Huro,
+    <a href="#Page_393">393</a></li>
+
+  <li>Hutton,
+    <a href="#Page_32">32</a></li>
+
+  <li>Huxley,
+    <a href="#Page_33">33</a></li>
+
+  <li>Hybernation,
+    <a href="#Page_188">188</a></li>
+
+  <li>Hybodontidæ,
+    <a href="#Page_328">328</a></li>
+
+  <li>Hybognathus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Hyborhynchus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Hybridism,
+    <a href="#Page_178">178</a></li>
+
+  <li>Hydrocyon,
+    <a href="#Page_611">611</a></li>
+
+  <li>Hygrogonus,
+    <a href="#Page_536">536</a></li>
+
+  <li>Hyodon,
+    <a href="#Page_653">653</a></li>
+
+  <li>Hyoid arch,
+    <a href="#Page_58">58</a></li>
+
+  <li>Hyomandibular,
+    <a href="#Page_55">55</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Hyoprorus,
+    <a href="#Page_674">674</a></li>
+
+  <li>Hyoptopoma,
+    <a href="#Page_578">578</a></li>
+
+  <li>Hyostylic skull,
+    <a href="#Page_74">74</a></li>
+
+  <li>Hypamia,
+    <a href="#Page_372">372</a></li>
+
+  <li>Hyperoglyphe,
+    <a href="#Page_387">387</a></li>
+
+  <li>Hyperopisus,
+    <a href="#Page_625">625</a></li>
+
+  <li>Hypnos,
+    <a href="#Page_340">340</a></li>
+
+  <li>Hypobranchial,
+    <a href="#Page_58">58</a></li>
+
+  <li>Hypomessus,
+    <a href="#Page_647">647</a></li>
+
+  <li>Hypophthalmichthys,
+    <a href="#Page_602">602</a></li>
+
+  <li>Hypophthalmus,
+    <a href="#Page_566">566</a></li>
+
+  <li>Hypophysis,
+    <a href="#Page_98">98</a></li>
+
+  <li>Hypotympanic,
+    <a href="#Page_55">55</a></li>
+
+  <li>Hypsinotus,
+    <a href="#Page_402">402</a></li>
+
+  <li>Hypsodon,
+    <a href="#Page_500">500</a></li>
+
+  <li>Hypural,
+    <a href="#Page_53">53</a>,
+    <a href="#Page_84">84</a></li>
+
+  <li>Hyrtl,
+    <a href="#Page_32">32</a></li>
+
+  <li>Hysterocarpus,
+    <a href="#Page_534">534</a></li>
+
+  <li>Hystricodon,
+    <a href="#Page_611">611</a></li>
+</ul>
+
+<ul>
+  <li>Icelus,
+    <a href="#Page_477">477</a></li>
+
+  <li>Ichthyborus,
+    <a href="#Page_612">612</a></li>
+
+  <li>Ichthyocampus,
+    <a href="#Page_681">681</a></li>
+
+  <li>Ichthyodorulites,
+    <a href="#Page_194">194</a></li>
+
+  <li>Ichthyomyzon,
+    <a href="#Page_693">693</a></li>
+
+  <li>Id,
+    <a href="#Page_599">599</a></li>
+
+  <li>Ikan sumpit,
+    <a href="#Page_403">403</a></li>
+
+  <li>Impregnation, artificial,
+    <a href="#Page_186">186</a></li>
+
+  <li>Indian region,
+    <a href="#Page_220">220</a></li>
+
+  <li>Indo-Pacific ocean,
+    <a href="#Page_278">278</a></li>
+
+  <li>Infraorbital,
+    <a href="#Page_54">54</a></li>
+
+  <li>Infundibulum,
+    <a href="#Page_98">98</a></li>
+
+  <li>Interhæmals,
+    <a href="#Page_53">53</a></li>
+
+  <li>Intermaxillary,
+    <a href="#Page_53">53</a></li>
+
+  <li>Interneurals,
+    <a href="#Page_53">53</a></li>
+
+  <li>Interoperculum,
+    <a href="#Page_38">38</a>,
+    <a href="#Page_55">55</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Intestine,
+    <a href="#Page_127">127</a></li>
+
+  <li>Ipnops,
+    <a href="#Page_585">585</a></li>
+
+  <li>Ischyodus,
+    <a href="#Page_349">349</a></li>
+
+  <li>Ischyrocephalus,
+    <a href="#Page_666">666</a></li>
+
+  <li>Isistius,
+    <a href="#Page_334">334</a></li>
+
+  <li>Isthmus,
+    <a href="#Page_39">39</a>,
+    <a href="#Page_58">58</a></li>
+
+  <li>Isurus,
+    <a href="#Page_457">457</a></li>
+</ul>
+
+<ul>
+  <li>Japanese District,
+    <a href="#Page_270">270</a></li>
+
+  <li>Jenyns,
+    <a href="#Page_27">27</a></li>
+
+  <li>Jenynsia,
+    <a href="#Page_616">616</a></li>
+
+  <li>John Dory,
+    <a href="#Page_451">451</a></li>
+
+  <li>Jugular fins,
+    <a href="#Page_42">42</a></li>
+
+  <li>Julis,
+    <a href="#Page_529">529</a></li>
+</ul>
+
+<ul>
+  <li>Kabeljau,
+    <a href="#Page_540">540</a></li>
+
+  <li>Kalm,
+    <a href="#Page_13">13</a></li>
+
+  <li>Kamtschatkan district,
+    <a href="#Page_269">269</a></li>
+
+  <li>Karausche,
+    <a href="#Page_591">591</a></li>
+
+  <li>Karpfen,
+    <a href="#Page_589">589</a></li>
+
+  <li>Kathetostoma,
+    <a href="#Page_463">463</a></li>
+
+  <li>Kaup,
+    <a href="#Page_33">33</a></li>
+
+  <li>Kelb el bahr,
+    <a href="#Page_611">611</a></li>
+
+  <li>Kelb el moyeh,
+    <a href="#Page_611">611</a></li>
+
+  <li>Kelp-fish,
+    <a href="#Page_533">533</a></li>
+
+  <li>Keris,
+    <a href="#Page_440">440</a></li>
+
+  <li>Ketengus,
+    <a href="#Page_569">569</a></li>
+
+  <li>Kidney,
+    <a href="#Page_155">155</a></li>
+
+  <li>King of the herrings,
+    <a href="#Page_522">522</a></li>
+
+  <li>Klein,
+    <a href="#Page_12">12</a></li>
+
+  <li>Klipvisch,
+    <a href="#Page_549">549</a></li>
+
+  <li>Klunzinger,
+    <a href="#Page_30">30</a></li>
+
+  <li>Kner,
+    <a href="#Page_27">27</a>,
+    <a href="#Page_28">28</a></li>
+
+  <li>Kneria,
+    <a href="#Page_606">606</a></li>
+
+  <li>Kokopu,
+    <a href="#Page_625">625</a></li>
+
+  <li>Kölliker,
+    <a href="#Page_32">32</a></li>
+
+  <li>Kovalevsky,
+    <a href="#Page_33">33</a></li>
+
+  <li>Kröyer,
+    <a href="#Page_27">27</a></li>
+
+  <li>Kurtus,
+    <a href="#Page_425">425</a></li>
+</ul>
+
+<ul>
+  <li>Labberdan,
+    <a href="#Page_540">540</a></li>
+
+  <li>Labeo,
+    <a href="#Page_593">593</a></li>
+
+  <li>Labials,
+    <a href="#Page_64">64</a>,
+    <a href="#Page_69">69</a></li>
+
+  <li>Labrax,
+    <a href="#Page_376">376</a></li>
+
+  <li>Labrichthys,
+    <a href="#Page_530">530</a></li>
+
+  <li>Labridæ,
+    <a href="#Page_525">525</a></li>
+
+  <li>Labroides,
+    <a href="#Page_530">530</a></li>
+
+  <li>Labrus,
+    <a href="#Page_526">526</a></li>
+
+  <li>Labyrinthici,
+    <a href="#Page_514">514</a></li>
+
+  <li>Lachnolæmus,
+    <a href="#Page_528">528</a></li>
+
+  <li>Lachs,
+    <a href="#Page_644">644</a></li>
+
+  <li>Lacépède,
+    <a href="#Page_15">15</a></li>
+
+  <li>Lactarius,
+    <a href="#Page_450">450</a></li>
+
+  <li>Ladislavia,
+    <a href="#Page_596">596</a></li>
+
+  <li>Læmargus,
+    <a href="#Page_333">333</a></li>
+
+  <li>Læmonema,
+    <a href="#Page_543">543</a></li>
+
+  <li>Læops,
+    <a href="#Page_557">557</a></li>
+
+  <li>Lais,
+    <a href="#Page_566">566</a></li>
+
+  <li>Laminæ branchiales,
+    <a href="#Page_136">136</a></li>
+
+  <li>Lamna,
+    <a href="#Page_320">320</a></li>
+
+  <li>Lamnidæ,
+    <a href="#Page_319">319</a></li>
+
+  <li>Lampern,
+    <a href="#Page_692">692</a></li>
+
+  <li>Lampris,
+    <a href="#Page_454">454</a></li>
+
+  <li>Lamprey,
+    <a href="#Page_692">692</a></li>
+
+  <li>Lancelet,
+    <a href="#Page_696">696</a></li>
+
+  <li>Lanioperca,
+    <a href="#Page_397">397</a></li>
+
+  <li>Larimus,
+    <a href="#Page_431">431</a></li>
+
+  <li>Lateral line,
+    <a href="#Page_48">48</a></li>
+
+  <li>Lates,
+    <a href="#Page_377">377</a></li>
+
+  <li>Latilus,
+    <a href="#Page_466">466</a></li>
+
+  <li>Latris,
+    <a href="#Page_412">412</a></li>
+
+  <li>Latrunculus,
+    <a href="#Page_486">486</a></li>
+
+  <li>Launce,
+    <a href="#Page_550">550</a></li>
+
+  <li>Leather-carp,
+    <a href="#Page_591">591</a></li>
+
+  <li>Lebiasina,
+    <a href="#Page_607">607</a></li>
+
+  <li>Lemon-sole,
+    <a href="#Page_558">558</a></li>
+
+  <li>Lentipes,
+    <a href="#Page_487">487</a></li>
+
+  <li>Lepadogaster,
+    <a href="#Page_513">513</a></li>
+
+  <li>Lepidoblennius,
+    <a href="#Page_498">498</a></li>
+
+  <li>Lepidocephalichthys,
+    <a href="#Page_606">606</a></li>
+
+  <li>Lepidocephalus,
+    <a href="#Page_606">606</a></li>
+
+  <li>Lepidocottus,
+    <a href="#Page_476">476</a></li>
+
+  <li>Lepidopsetta,
+    <a href="#Page_556">556</a></li>
+
+  <li>Lepidopus,
+    <a href="#Page_435">435</a></li>
+
+  <li>Lepidosiren,
+    <a href="#Page_355">355</a></li>
+
+  <li>Lepidosteidæ,
+    <a href="#Page_367">367</a></li>
+
+  <li>Lepidotrigla,
+    <a href="#Page_479">479</a></li>
+
+  <li>Lepidotus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Lepidozygus,
+    <a href="#Page_525">525</a></li>
+
+  <li>Leporinus,
+    <a href="#Page_608">608</a></li>
+
+  <li>Lepracanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Leptacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Leptobarbus,
+    <a href="#Page_597">597</a></li>
+
+  <li>Leptocarcharias,
+    <a href="#Page_319">319</a></li>
+
+  <li>Leptocardii,
+    <a href="#Page_696">696</a></li>
+
+  <li>Leptocephali,
+    <a href="#Page_179">179</a></li>
+
+  <li>Leptoichthys,
+    <a href="#Page_681">681</a></li>
+
+  <li>Leptojulis,
+    <a href="#Page_529">529</a></li>
+
+  <li>Leptolepidæ,
+    <a href="#Page_371">371</a></li>
+
+  <li>Leptopterygius,
+    <a href="#Page_513">513</a></li>
+
+  <li>Leptoscopus,
+    <a href="#Page_463">463</a></li>
+
+  <li>Leptosomus,
+    <a href="#Page_656">656</a></li>
+
+  <li>Leptotrachelus,
+    <a href="#Page_666">666</a></li>
+
+  <li>Lesson,
+    <a href="#Page_26">26</a></li>
+
+  <li>Lethrinus,
+    <a href="#Page_407">407</a></li>
+
+  <li>Leucaspius,
+    <a href="#Page_604">604</a></li>
+
+  <li>Leuciscus,
+    <a href="#Page_598">598</a></li>
+
+  <li>Leucosomus,
+    <a href="#Page_600">600</a></li>
+
+  <li>Liacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Liachirus,
+    <a href="#Page_558">558</a></li>
+
+  <li>Liassic fishes,
+    <a href="#Page_198">198</a></li>
+
+  <li>Lichia,
+    <a href="#Page_446">446</a></li>
+
+  <li>Ligamentum longitudinale,
+    <a href="#Page_72">72</a></li>
+
+  <li>Limnurgus,
+    <a href="#Page_615">615</a></li>
+
+  <li>Ling,
+    <a href="#Page_544">544</a>,
+    <a href="#Page_549">549</a></li>
+
+  <li>Linnæus,
+    <a href="#Page_10">10</a></li>
+
+  <li>Liocassis,
+    <a href="#Page_567">567</a></li>
+
+  <li>Liopsetta,
+    <a href="#Page_556">556</a></li>
+
+  <li>Lioscorpius,
+    <a href="#Page_415">415</a></li>
+
+  <li>Liparis,
+    <a href="#Page_485">485</a></li>
+
+  <li>Liposarcus,
+    <a href="#Page_576">576</a></li>
+
+  <li>Liver,
+    <a href="#Page_132">132</a></li>
+
+  <li>Loach,
+    <a href="#Page_604">604</a></li>
+
+  <li>Lobotes,
+    <a href="#Page_387">387</a></li>
+
+  <li>Lonchurus,
+    <a href="#Page_431">431</a></li>
+
+  <li>Lophiogobius,
+    <a href="#Page_487">487</a></li>
+
+  <li>Lophiosilurus,
+    <a href="#Page_569">569</a></li>
+
+  <li>Lophiostomus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Lophius,
+    <a href="#Page_470">470</a></li>
+
+  <li>Lophobranchii,
+    <a href="#Page_678">678</a></li>
+
+  <li>Lophonectes,
+    <a href="#Page_556">556</a></li>
+
+  <li>Loricaria,
+    <a href="#Page_578">578</a></li>
+
+  <li>Lota,
+    <a href="#Page_544">544</a></li>
+
+  <li>Lotella,
+    <a href="#Page_543">543</a></li>
+
+  <li>Loxodon,
+    <a href="#Page_319">319</a></li>
+
+  <li>Lucania,
+    <a href="#Page_615">615</a></li>
+
+  <li>Lucifuga,
+    <a href="#Page_547">547</a></li>
+
+  <li>Luciocephalidæ,
+    <a href="#Page_519">519</a></li>
+
+  <li>Luciogobius,
+    <a href="#Page_489">489</a></li>
+
+  <li>Lucioperca,
+    <a href="#Page_378">378</a></li>
+
+  <li>Luciosoma,
+    <a href="#Page_598">598</a></li>
+
+  <li>Luciotrutta,
+    <a href="#Page_646">646</a></li>
+
+  <li>Lump-sucker,
+    <a href="#Page_484">484</a></li>
+
+  <li>Lütken,
+    <a href="#Page_32">32</a></li>
+
+  <li>Lycodes,
+    <a href="#Page_537">537</a></li>
+</ul>
+
+<ul>
+  <li>Mackerel,
+    <a href="#Page_456">456</a>,
+    <a href="#Page_457">457</a></li>
+
+  <li>Mackerel Midge,
+    <a href="#Page_544">544</a></li>
+
+  <li>Macrodon,
+    <a href="#Page_607">607</a></li>
+
+  <li>Macrolepis,
+    <a href="#Page_421">421</a></li>
+
+  <li>Macrones,
+    <a href="#Page_567">567</a></li>
+
+  <li>Macropoma,
+    <a href="#Page_365">365</a></li>
+
+  <li>Macropus,
+    <a href="#Page_517">517</a></li>
+
+  <li>Macrosemius,
+    <a href="#Page_368">368</a></li>
+
+  <li>Macruridæ,
+    <a href="#Page_557">557</a></li>
+
+  <li>Macruronus,
+    <a href="#Page_552">552</a></li>
+
+  <li>Macrurus,
+    <a href="#Page_552">552</a></li>
+
+  <li>Mæna,
+    <a href="#Page_390">390</a></li>
+
+  <li>Mahaseer,
+    <a href="#Page_594">594</a></li>
+
+  <li>Malacanthus,
+    <a href="#Page_467">467</a></li>
+
+  <li>Malacocephalus,
+    <a href="#Page_552">552</a></li>
+
+  <li>Malacopterus,
+    <a href="#Page_528">528</a></li>
+
+  <li>Malacopterygian,
+    <a href="#Page_41">41</a></li>
+
+  <li>Malacosteus,
+    <a href="#Page_629">629</a></li>
+
+  <li>Malapterurus,
+    <a href="#Page_574">574</a></li>
+
+  <li>Mallotus,
+    <a href="#Page_647">647</a></li>
+
+  <li>Malpighi,
+    <a href="#Page_7">7</a></li>
+
+  <li>Malpighian corpuscle,
+    <a href="#Page_155">155</a></li>
+
+  <li>Malthe,
+    <a href="#Page_475">475</a></li>
+
+  <li>Mandible,
+    <a href="#Page_54">54</a></li>
+
+  <li>Margrav,
+    <a href="#Page_7">7</a></li>
+
+  <li>Marine fishes,
+    <a href="#Page_254">254</a></li>
+
+  <li>Mary sole,
+    <a href="#Page_555">555</a></li>
+
+  <li>Maskinonge,
+    <a href="#Page_624">624</a></li>
+
+  <li>Mastacembelus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Mastoid,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_88">88</a></li>
+
+  <li>Maurolicus,
+    <a href="#Page_628">628</a></li>
+
+  <li>Maynea,
+    <a href="#Page_538">538</a></li>
+
+  <li>Maxillary,
+    <a href="#Page_53">53</a>,
+    <a href="#Page_90">90</a></li>
+
+  <li>Meagre,
+    <a href="#Page_427">427</a></li>
+
+  <li>Meckel’s cartilage,
+    <a href="#Page_54">54</a></li>
+
+  <li>Meda,
+    <a href="#Page_601">601</a></li>
+
+  <li>Mediterranean district,
+    <a href="#Page_264">264</a></li>
+
+  <li>Medulla oblongata,
+    <a href="#Page_98">98</a></li>
+
+  <li>Megalichthys,
+    <a href="#Page_365">365</a></li>
+
+  <li>Megalobrycon,
+    <a href="#Page_610">610</a></li>
+
+  <li>Megalops,
+    <a href="#Page_661">661</a></li>
+
+  <li>Meidinger,
+    <a href="#Page_13">13</a></li>
+
+  <li>Melamphaes,
+    <a href="#Page_423">423</a></li>
+
+  <li>Melanocetus,
+    <a href="#Page_473">473</a></li>
+
+  <li>Melanonus,
+    <a href="#Page_541">541</a></li>
+
+  <li>Membrane-bones,
+    <a href="#Page_75">75</a>,
+    <a href="#Page_84">84</a></li>
+
+  <li>Mendosoma,
+    <a href="#Page_412">412</a></li>
+
+  <li>Mene,
+    <a href="#Page_455">455</a></li>
+
+  <li>Menhaden,
+    <a href="#Page_659">659</a></li>
+
+  <li>Merluccius,
+    <a href="#Page_542">542</a></li>
+
+  <li>Mesencephalon,
+    <a href="#Page_97">97</a></li>
+
+  <li>Mesoarium,
+    <a href="#Page_158">158</a></li>
+
+  <li>Mesodon,
+    <a href="#Page_367">367</a></li>
+
+  <li>Mesogaster,
+    <a href="#Page_500">500</a></li>
+
+  <li>Mesolepis,
+    <a href="#Page_370">370</a></li>
+
+  <li>Mesonauta,
+    <a href="#Page_536">536</a></li>
+
+  <li>Mesoprion,
+    <a href="#Page_384">384</a></li>
+
+  <li>Mesops,
+    <a href="#Page_537">537</a></li>
+
+  <li>Mesopterygium,
+    <a href="#Page_70">70</a></li>
+
+  <li>Mesotympanic,
+    <a href="#Page_55">55</a></li>
+
+  <li>Mesturus,
+    <a href="#Page_367">367</a></li>
+
+  <li>Metacarpals,
+    <a href="#Page_59">59</a></li>
+
+  <li>Metamorphosis,
+    <a href="#Page_170">170</a></li>
+
+  <li>Metapterygium,
+    <a href="#Page_70">70</a></li>
+
+  <li>Metapterygoid,
+    <a href="#Page_55">55</a>,
+    <a href="#Page_90">90</a></li>
+
+  <li>Metencephalon,
+    <a href="#Page_97">97</a></li>
+
+  <li>Micracanthus,
+    <a href="#Page_519">519</a></li>
+
+  <li>Microconodus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Microdesmus,
+    <a href="#Page_538">538</a></li>
+
+  <li>Microdon,
+    <a href="#Page_367">367</a></li>
+
+  <li>Micropogon,
+    <a href="#Page_428">428</a></li>
+
+  <li>Micropteryx,
+    <a href="#Page_443">443</a></li>
+
+  <li>Micropus,
+    <a href="#Page_416">416</a></li>
+
+  <li>Microstoma,
+    <a href="#Page_650">650</a></li>
+
+  <li>Miller’s-thumb,
+    <a href="#Page_476">476</a></li>
+
+  <li>Minnow,
+    <a href="#Page_596">596</a>,
+    <a href="#Page_599">599</a></li>
+
+  <li>Minous,
+    <a href="#Page_417">417</a></li>
+
+  <li>Misgurnus,
+    <a href="#Page_604">604</a></li>
+
+  <li>Mishcup,
+    <a href="#Page_408">408</a></li>
+
+  <li>Mitchell,
+    <a href="#Page_17">17</a></li>
+
+  <li>Mixogamous,
+    <a href="#Page_177">177</a></li>
+
+  <li>Mollienesia,
+    <a href="#Page_617">617</a></li>
+
+  <li>Molva,
+    <a href="#Page_544">544</a></li>
+
+  <li>Monacanthus,
+    <a href="#Page_684">684</a></li>
+
+  <li>Monk-fish,
+    <a href="#Page_334">334</a></li>
+
+  <li>Monocentris,
+    <a href="#Page_421">421</a></li>
+
+  <li>Monocirrhus,
+    <a href="#Page_418">418</a></li>
+
+  <li>Monopterus,
+    <a href="#Page_669">669</a></li>
+
+  <li>Moon-eye,
+    <a href="#Page_653">653</a></li>
+
+  <li>Mora,
+    <a href="#Page_541">541</a></li>
+
+  <li>Mordacia,
+    <a href="#Page_693">693</a></li>
+
+  <li>Moringua,
+    <a href="#Page_675">675</a></li>
+
+  <li>Mormyrops,
+    <a href="#Page_626">626</a></li>
+
+  <li>Mormyrus,
+    <a href="#Page_625">625</a></li>
+
+  <li>Mossbanker,
+    <a href="#Page_659">659</a></li>
+
+  <li>Motella,
+    <a href="#Page_544">544</a></li>
+
+  <li>Mouth,
+    <a href="#Page_37">37</a>,
+    <a href="#Page_123">123</a></li>
+
+  <li>Moxostoma,
+    <a href="#Page_589">589</a></li>
+
+  <li>Mud-fish,
+    <a href="#Page_372">372</a>,
+    <a href="#Page_619">619</a></li>
+
+  <li>Mugil,
+    <a href="#Page_501">501</a></li>
+
+  <li>Müller, H.,
+    <a href="#Page_33">33</a></li>
+
+  <li>Müller, J.,
+    <a href="#Page_22">22</a>,
+    <a href="#Page_32">32</a>,
+    <a href="#Page_33">33</a></li>
+
+  <li>Müller, O. F.,
+    <a href="#Page_13">13</a></li>
+
+  <li>Müller, W.,
+    <a href="#Page_33">33</a></li>
+
+  <li>Mullidæ,
+    <a href="#Page_403">403</a></li>
+
+  <li>Mulloides,
+    <a href="#Page_404">404</a></li>
+
+  <li>Mullus,
+    <a href="#Page_404">404</a></li>
+
+  <li>Munro,
+    <a href="#Page_16">16</a></li>
+
+  <li>Muræna,
+    <a href="#Page_675">675</a></li>
+
+  <li>Murænesox,
+    <a href="#Page_674">674</a></li>
+
+  <li>Murænichthys,
+    <a href="#Page_674">674</a></li>
+
+  <li>Murænolepis,
+    <a href="#Page_545">545</a></li>
+
+  <li>Murray-Cod,
+    <a href="#Page_392">392</a></li>
+
+  <li>Muscles,
+    <a href="#Page_93">93</a></li>
+
+  <li>Muskellunge,
+    <a href="#Page_624">624</a></li>
+
+  <li>Mustelus,
+    <a href="#Page_318">318</a></li>
+
+  <li>Mylesinus,
+    <a href="#Page_613">613</a></li>
+
+  <li>Myletes,
+    <a href="#Page_613">613</a></li>
+
+  <li>Myliobatis,
+    <a href="#Page_344">344</a></li>
+
+  <li>Mylocyprinus,
+    <a href="#Page_588">588</a></li>
+
+  <li>Myloleucus,
+    <a href="#Page_601">601</a></li>
+
+  <li>Mylopharodon,
+    <a href="#Page_601">601</a></li>
+
+  <li>Myology,
+    <a href="#Page_93">93</a></li>
+
+  <li>Myriacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Myriodon,
+    <a href="#Page_383">383</a></li>
+
+  <li>Myriolepis,
+    <a href="#Page_370">370</a></li>
+
+  <li>Myripristis,
+    <a href="#Page_423">423</a></li>
+
+  <li>Myroconger,
+    <a href="#Page_677">677</a></li>
+
+  <li>Myrophis,
+    <a href="#Page_674">674</a></li>
+
+  <li>Myrus,
+    <a href="#Page_674">674</a></li>
+
+  <li>Mystacoleucus,
+    <a href="#Page_598">598</a></li>
+
+  <li>Myxine,
+    <a href="#Page_695">695</a></li>
+
+  <li>Myxodes,
+    <a href="#Page_498">498</a></li>
+
+  <li>Myxus,
+    <a href="#Page_504">504</a></li>
+</ul>
+
+<ul>
+  <li>Nandus,
+    <a href="#Page_418">418</a></li>
+
+  <li>Nannœthiops,
+    <a href="#Page_610">610</a></li>
+
+  <li>Nannobrachium,
+    <a href="#Page_587">587</a></li>
+
+  <li>Nannocampus,
+    <a href="#Page_681">681</a></li>
+
+  <li>Nannocharax,
+    <a href="#Page_608">608</a></li>
+
+  <li>Nannostomus,
+    <a href="#Page_607">607</a></li>
+
+  <li>Narcine,
+    <a href="#Page_340">340</a></li>
+
+  <li>Naseus,
+    <a href="#Page_438">438</a>,
+    <a href="#Page_440">440</a></li>
+
+  <li>Nauclerus,
+    <a href="#Page_446">446</a></li>
+
+  <li>Naucrates,
+    <a href="#Page_444">444</a></li>
+
+  <li>Nautichthys,
+    <a href="#Page_480">480</a></li>
+
+  <li>Nealotus,
+    <a href="#Page_434">434</a></li>
+
+  <li>Nearctic region,
+    <a href="#Page_246">246</a></li>
+
+  <li>Nebris,
+    <a href="#Page_431">431</a></li>
+
+  <li>Nebrius,
+    <a href="#Page_326">326</a></li>
+
+  <li>Neetroplus,
+    <a href="#Page_536">536</a></li>
+
+  <li>Nefasch,
+    <a href="#Page_612">612</a></li>
+
+  <li>Nemacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Nemachilus,
+    <a href="#Page_605">605</a></li>
+
+  <li>Nemadactylus,
+    <a href="#Page_412">412</a></li>
+
+  <li>Nematogenys,
+    <a href="#Page_581">581</a></li>
+
+  <li>Nematops,
+    <a href="#Page_557">557</a></li>
+
+  <li>Nematoptychius,
+    <a href="#Page_370">370</a></li>
+
+  <li>Nemichthys,
+    <a href="#Page_670">670</a></li>
+
+  <li>Nemophis,
+    <a href="#Page_498">498</a></li>
+
+  <li>Nemopteryx,
+    <a href="#Page_434">434</a>,
+    <a href="#Page_539">539</a></li>
+
+  <li>Neochanna,
+    <a href="#Page_624">624</a></li>
+
+  <li>Neoclinus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Neoconger,
+    <a href="#Page_674">674</a></li>
+
+  <li>Neophrynichthys,
+    <a href="#Page_469">469</a></li>
+
+  <li>Neotropical region,
+    <a href="#Page_233">233</a></li>
+
+  <li>Nerfling,
+    <a href="#Page_599">599</a></li>
+
+  <li>Nerophis,
+    <a href="#Page_681">681</a></li>
+
+  <li>Nerves,
+    <a href="#Page_103">103</a></li>
+
+  <li>Nesiarchus,
+    <a href="#Page_434">434</a></li>
+
+  <li>Nettastoma,
+    <a href="#Page_674">674</a></li>
+
+  <li>Neural arches,
+    <a href="#Page_85">85</a></li>
+
+  <li>Neural spine,
+    <a href="#Page_52">52</a></li>
+
+  <li>Neurapophyses,
+    <a href="#Page_51">51</a></li>
+
+  <li>Neurology,
+    <a href="#Page_96">96</a></li>
+
+  <li>Neuroskeleton,
+    <a href="#Page_85">85</a></li>
+
+  <li>New Zealand sub-region,
+    <a href="#Page_248">248</a></li>
+
+  <li>Nictitating membrane,
+    <a href="#Page_113">113</a></li>
+
+  <li>Nilsson,
+    <a href="#Page_27">27</a></li>
+
+  <li>Niphon,
+    <a href="#Page_397">397</a></li>
+
+  <li>Nomeidæ,
+    <a href="#Page_455">455</a></li>
+
+  <li>Nomeus,
+    <a href="#Page_456">456</a></li>
+
+  <li>Nonnat,
+    <a href="#Page_501">501</a></li>
+
+  <li>Nordmann,
+    <a href="#Page_28">28</a></li>
+
+  <li>North American district,
+    <a href="#Page_266">266</a></li>
+
+  <li>North American region,
+    <a href="#Page_246">246</a></li>
+
+  <li>North Atlantic,
+    <a href="#Page_262">262</a></li>
+
+  <li>Northern temperate zone,
+    <a href="#Page_262">262</a></li>
+
+  <li>Northern zone,
+    <a href="#Page_240">240</a></li>
+
+  <li>North Pacific,
+    <a href="#Page_268">268</a></li>
+
+  <li>Nostrils,
+    <a href="#Page_37">37</a>,
+    <a href="#Page_109">109</a></li>
+
+  <li>Notacanthus,
+    <a href="#Page_523">523</a></li>
+
+  <li>Notidanus,
+    <a href="#Page_325">325</a></li>
+
+  <li>Notochord,
+    <a href="#Page_63">63</a></li>
+
+  <li>Notoglanis,
+    <a href="#Page_569">569</a></li>
+
+  <li>Notograptus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Notopterus,
+    <a href="#Page_665">665</a></li>
+
+  <li>Notothenia,
+    <a href="#Page_466">466</a></li>
+
+  <li>Noturus,
+    <a href="#Page_568">568</a></li>
+
+  <li>Novacula,
+    <a href="#Page_529">529</a></li>
+
+  <li>Nummopalatus,
+    <a href="#Page_526">526</a></li>
+
+  <li>Nuria,
+    <a href="#Page_598">598</a></li>
+
+  <li>Nutrition, organs of,
+    <a href="#Page_121">121</a></li>
+</ul>
+
+<ul>
+  <li>Oar-Fish,
+    <a href="#Page_522">522</a></li>
+
+  <li>Oblata,
+    <a href="#Page_406">406</a></li>
+
+  <li>Occipital,
+    <a href="#Page_56">56</a></li>
+
+  <li>Ochetobius,
+    <a href="#Page_602">602</a></li>
+
+  <li>Odax,
+    <a href="#Page_532">532</a></li>
+
+  <li>Odontaspis,
+    <a href="#Page_321">321</a></li>
+
+  <li>Odonteus,
+    <a href="#Page_525">525</a></li>
+
+  <li>Odontostomus,
+    <a href="#Page_587">587</a></li>
+
+  <li>Oil-sardine,
+    <a href="#Page_660">660</a></li>
+
+  <li>Old Red Sandstone,
+    <a href="#Page_194">194</a></li>
+
+  <li>Old wife,
+    <a href="#Page_406">406</a></li>
+
+  <li>Olfactory lobes,
+    <a href="#Page_97">97</a></li>
+
+  <li>Olfactory organ,
+    <a href="#Page_109">109</a></li>
+
+  <li>Oligorus,
+    <a href="#Page_392">392</a></li>
+
+  <li>Oligosarcus,
+    <a href="#Page_611">611</a></li>
+
+  <li>Olistherops,
+    <a href="#Page_533">533</a></li>
+
+  <li>Ombre,
+    <a href="#Page_429">429</a></li>
+
+  <li>Ombre chevalier,
+    <a href="#Page_645">645</a></li>
+
+  <li>Omentum,
+    <a href="#Page_132">132</a></li>
+
+  <li>Onchus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Oncorhynchus,
+    <a href="#Page_646">646</a></li>
+
+  <li>Oneirodes,
+    <a href="#Page_473">473</a></li>
+
+  <li>Oolithic fishes,
+    <a href="#Page_199">199</a></li>
+
+  <li>Opercular gill,
+    <a href="#Page_138">138</a></li>
+
+  <li>Operculum,
+    <a href="#Page_38">38</a>,
+    <a href="#Page_54">54</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Ophichthys,
+    <a href="#Page_674">674</a></li>
+
+  <li>Ophidiidæ,
+    <a href="#Page_546">546</a></li>
+
+  <li>Ophidium,
+    <a href="#Page_549">549</a></li>
+
+  <li>Ophiocephalidæ,
+    <a href="#Page_513">513</a></li>
+
+  <li>Ophiodon,
+    <a href="#Page_491">491</a></li>
+
+  <li>Ophiopsis,
+    <a href="#Page_368">368</a></li>
+
+  <li>Opisthognathus,
+    <a href="#Page_466">466</a></li>
+
+  <li>Opisthopteryx,
+    <a href="#Page_656">656</a></li>
+
+  <li>Opisthoticum,
+    <a href="#Page_88">88</a></li>
+
+  <li>Opsariichthys,
+    <a href="#Page_602">602</a></li>
+
+  <li>Optic lobes,
+    <a href="#Page_97">97</a></li>
+
+  <li>Oracanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Orbitosphenoid,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_88">88</a></li>
+
+  <li>Oreinus,
+    <a href="#Page_595">595</a></li>
+
+  <li>Oreonectes,
+    <a href="#Page_606">606</a></li>
+
+  <li>Orestias,
+    <a href="#Page_615">615</a></li>
+
+  <li>Orfe,
+    <a href="#Page_599">599</a></li>
+
+  <li>Orthacanthus,
+    <a href="#Page_334">334</a></li>
+
+  <li>Orthagoriscus,
+    <a href="#Page_690">690</a></li>
+
+  <li>Orthodon,
+    <a href="#Page_601">601</a></li>
+
+  <li>Orthostomus,
+    <a href="#Page_489">489</a></li>
+
+  <li>Osbeck,
+    <a href="#Page_13">13</a></li>
+
+  <li>Osmeroides,
+    <a href="#Page_582">582</a>,
+    <a href="#Page_631">631</a></li>
+
+  <li>Osmerus,
+    <a href="#Page_646">646</a></li>
+
+  <li>Os operculare,
+    <a href="#Page_91">91</a></li>
+
+  <li>Osphromenus,
+    <a href="#Page_517">517</a></li>
+
+  <li>Osteobrama,
+    <a href="#Page_604">604</a></li>
+
+  <li>Osteochilus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Osteogeniosus,
+    <a href="#Page_569">569</a></li>
+
+  <li>Osteoglossum,
+    <a href="#Page_654">654</a></li>
+
+  <li>Osteolepis,
+    <a href="#Page_365">365</a></li>
+
+  <li>Ostracion,
+    <a href="#Page_686">686</a></li>
+
+  <li>Os transversum,
+    <a href="#Page_56">56</a></li>
+
+  <li>Otolith,
+    <a href="#Page_116">116</a></li>
+
+  <li>Otolithus,
+    <a href="#Page_430">430</a></li>
+
+  <li>Oulachon,
+    <a href="#Page_647">647</a></li>
+
+  <li>Ovaries,
+    <a href="#Page_158">158</a>,
+    <a href="#Page_166">166</a></li>
+
+  <li>Ovum,
+    <a href="#Page_158">158</a>,
+    <a href="#Page_159">159</a>,
+    <a href="#Page_167">167</a></li>
+
+  <li>Owen,
+    <a href="#Page_33">33</a></li>
+
+  <li>Oxuderces,
+    <a href="#Page_489">489</a></li>
+
+  <li>Oxyconger,
+    <a href="#Page_674">674</a></li>
+
+  <li>Oxydoras,
+    <a href="#Page_572">572</a></li>
+
+  <li>Oxygnathus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Oxymetopon,
+    <a href="#Page_489">489</a></li>
+
+  <li>Oxyrhina,
+    <a href="#Page_320">320</a></li>
+
+  <li>Oxytes,
+    <a href="#Page_319">319</a></li>
+</ul>
+
+<ul>
+  <li>Pachycormus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Pachymetopon,
+    <a href="#Page_406">406</a></li>
+
+  <li>Pachyurus,
+    <a href="#Page_430">430</a></li>
+
+  <li>Pagellus,
+    <a href="#Page_408">408</a></li>
+
+  <li>Pagrus,
+    <a href="#Page_408">408</a></li>
+
+  <li>Paired fins,
+    <a href="#Page_42">42</a></li>
+
+  <li>Palæarctic region,
+    <a href="#Page_243">243</a></li>
+
+  <li>Palæichthyes,
+    <a href="#Page_312">312</a></li>
+
+  <li>Palæogadus,
+    <a href="#Page_539">539</a></li>
+
+  <li>Palæoniscidæ,
+    <a href="#Page_369">369</a></li>
+
+  <li>Palæorhynchus,
+    <a href="#Page_437">437</a></li>
+
+  <li>Palæeoscyllium,
+    <a href="#Page_326">326</a></li>
+
+  <li>Palæospinax,
+    <a href="#Page_330">330</a></li>
+
+  <li>Palatine,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_90">90</a></li>
+
+  <li>Palatine arch,
+    <a href="#Page_55">55</a></li>
+
+  <li>Palimphyes,
+    <a href="#Page_457">457</a></li>
+
+  <li>Pallas,
+    <a href="#Page_13">13</a></li>
+
+  <li>Pammelas,
+    <a href="#Page_447">447</a></li>
+
+  <li>Pancreas,
+    <a href="#Page_133">133</a></li>
+
+  <li>Pangasius,
+    <a href="#Page_566">566</a></li>
+
+  <li>Pantodon,
+    <a href="#Page_653">653</a></li>
+
+  <li>Papilla urogenitalis,
+    <a href="#Page_156">156</a></li>
+
+  <li>Paracanthobrama,
+    <a href="#Page_598">598</a></li>
+
+  <li>Paradiplomystax,
+    <a href="#Page_569">569</a></li>
+
+  <li>Paradise-fish,
+    <a href="#Page_517">517</a></li>
+
+  <li>Paragoniates,
+    <a href="#Page_610">610</a></li>
+
+  <li>Paralepis,
+    <a href="#Page_585">585</a></li>
+
+  <li>Paralichthys,
+    <a href="#Page_556">556</a></li>
+
+  <li>Paramisgurnus,
+    <a href="#Page_606">606</a></li>
+
+  <li>Paramyrus,
+    <a href="#Page_674">674</a></li>
+
+  <li>Paraperca,
+    <a href="#Page_375">375</a></li>
+
+  <li>Paraphoxinus,
+    <a href="#Page_601">601</a></li>
+
+  <li>Parapophyses,
+    <a href="#Page_51">51</a></li>
+
+  <li>Parascopelus,
+    <a href="#Page_582">582</a></li>
+
+  <li>Parascyllium,
+    <a href="#Page_326">326</a></li>
+
+  <li>Parasphenoid,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Pardachirus,
+    <a href="#Page_558">558</a></li>
+
+  <li>Paretroplus,
+    <a href="#Page_535">535</a></li>
+
+  <li>Parietals,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Pariodon,
+    <a href="#Page_581">581</a></li>
+
+  <li>Parker,
+    <a href="#Page_32">32</a></li>
+
+  <li>Parma,
+    <a href="#Page_525">525</a></li>
+
+  <li>Parnell,
+    <a href="#Page_27">27</a></li>
+
+  <li>Paroccipital,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_88">88</a></li>
+
+  <li>Parodon,
+    <a href="#Page_607">607</a></li>
+
+  <li>Parophrys,
+    <a href="#Page_557">557</a></li>
+
+  <li>Paropsis,
+    <a href="#Page_450">450</a></li>
+
+  <li>Parra,
+    <a href="#Page_13">13</a></li>
+
+  <li>Parr-marks,
+    <a href="#Page_631">631</a></li>
+
+  <li>Parrot-wrasses,
+    <a href="#Page_530">530</a></li>
+
+  <li>Patæcus,
+    <a href="#Page_497">497</a></li>
+
+  <li>Patagonian district,
+    <a href="#Page_289">289</a></li>
+
+  <li>Peal,
+    <a href="#Page_644">644</a></li>
+
+  <li>Pectoral arch,
+    <a href="#Page_92">92</a></li>
+
+  <li>Pectoral fins,
+    <a href="#Page_42">42</a></li>
+
+  <li>Pediculati,
+    <a href="#Page_469">469</a></li>
+
+  <li>Pegasus,
+    <a href="#Page_482">482</a></li>
+
+  <li>Pelagic fishes,
+    <a href="#Page_292">292</a></li>
+
+  <li>Pelamys,
+    <a href="#Page_459">459</a></li>
+
+  <li>Pelargorhynchus,
+    <a href="#Page_666">666</a></li>
+
+  <li>Pelecus,
+    <a href="#Page_604">604</a></li>
+
+  <li>Pelerin,
+    <a href="#Page_322">322</a></li>
+
+  <li>Pellona,
+    <a href="#Page_660">660</a></li>
+
+  <li>Pellonula,
+    <a href="#Page_660">660</a></li>
+
+  <li>Pelor,
+    <a href="#Page_417">417</a></li>
+
+  <li>Pelotrophus,
+    <a href="#Page_604">604</a></li>
+
+  <li>Peltorhamphus,
+    <a href="#Page_557">557</a></li>
+
+  <li>Pempheris,
+    <a href="#Page_425">425</a></li>
+
+  <li>Pennant,
+    <a href="#Page_13">13</a></li>
+
+  <li>Pentaceros,
+    <a href="#Page_397">397</a></li>
+
+  <li>Pentanemus,
+    <a href="#Page_425">425</a></li>
+
+  <li>Pentapus,
+    <a href="#Page_390">390</a></li>
+
+  <li>Pentaroge,
+    <a href="#Page_417">417</a></li>
+
+  <li>Perca,
+    <a href="#Page_375">375</a></li>
+
+  <li>Percalabrax,
+    <a href="#Page_378">378</a></li>
+
+  <li>Perch,
+    <a href="#Page_375">375</a></li>
+
+  <li>Percichthys,
+    <a href="#Page_376">376</a></li>
+
+  <li>Percidæ,
+    <a href="#Page_375">375</a></li>
+
+  <li>Percilia,
+    <a href="#Page_397">397</a></li>
+
+  <li>Percis,
+    <a href="#Page_464">464</a></li>
+
+  <li>Percophis,
+    <a href="#Page_466">466</a></li>
+
+  <li>Percopsis,
+    <a href="#Page_651">651</a></li>
+
+  <li>Periophthalmus,
+    <a href="#Page_487">487</a></li>
+
+  <li>Peristethus,
+    <a href="#Page_481">481</a></li>
+
+  <li>Permian fishes,
+    <a href="#Page_197">197</a></li>
+
+  <li>Peruvian district,
+    <a href="#Page_280">280</a></li>
+
+  <li>Pesce Rey,
+    <a href="#Page_501">501</a></li>
+
+  <li>Petalopteryx,
+    <a href="#Page_480">480</a></li>
+
+  <li>Petenia,
+    <a href="#Page_536">536</a></li>
+
+  <li>Peters,
+    <a href="#Page_31">31</a></li>
+
+  <li>Petrodus,
+    <a href="#Page_329">329</a></li>
+
+  <li>Petromyzon,
+    <a href="#Page_692">692</a></li>
+
+  <li>Petrosal,
+    <a href="#Page_56">56</a></li>
+
+  <li>Petroscirtes,
+    <a href="#Page_494">494</a></li>
+
+  <li>Phaneropleuridæ,
+    <a href="#Page_360">360</a></li>
+
+  <li>Pharyngeal bones,
+    <a href="#Page_58">58</a></li>
+
+  <li>Pharyngognathi,
+    <a href="#Page_523">523</a></li>
+
+  <li>Pholidichthys,
+    <a href="#Page_498">498</a></li>
+
+  <li>Pholidophorus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Photichthys,
+    <a href="#Page_629">629</a></li>
+
+  <li>Phractocephalus,
+    <a href="#Page_568">568</a></li>
+
+  <li>Phrynorhombus,
+    <a href="#Page_555">555</a></li>
+
+  <li>Phycis,
+    <a href="#Page_543">543</a></li>
+
+  <li>Phyllodus,
+    <a href="#Page_526">526</a></li>
+
+  <li>Phyllopteryx,
+    <a href="#Page_682">682</a></li>
+
+  <li>Physiculus,
+    <a href="#Page_543">543</a></li>
+
+  <li>Physostomi,
+    <a href="#Page_559">559</a></li>
+
+  <li>Piabuca,
+    <a href="#Page_610">610</a></li>
+
+  <li>Piabucina,
+    <a href="#Page_610">610</a></li>
+
+  <li>Pickerell,
+    <a href="#Page_624">624</a></li>
+
+  <li>Pike,
+    <a href="#Page_624">624</a></li>
+
+  <li>Pike-perch,
+    <a href="#Page_378">378</a></li>
+
+  <li>Pilchard,
+    <a href="#Page_660">660</a></li>
+
+  <li>Pileoma,
+    <a href="#Page_379">379</a></li>
+
+  <li>Pilot-fish,
+    <a href="#Page_444">444</a></li>
+
+  <li>Pimelepterus,
+    <a href="#Page_410">410</a></li>
+
+  <li>Pimelodus,
+    <a href="#Page_568">568</a></li>
+
+  <li>Pimephales,
+    <a href="#Page_596">596</a></li>
+
+  <li>Pinguipes,
+    <a href="#Page_466">466</a></li>
+
+  <li>Pipe-fishes,
+    <a href="#Page_680">680</a></li>
+
+  <li>Piramutana,
+    <a href="#Page_568">568</a></li>
+
+  <li>Piratinga,
+    <a href="#Page_568">568</a></li>
+
+  <li>Pirinampus,
+    <a href="#Page_569">569</a></li>
+
+  <li>Piso,
+    <a href="#Page_7">7</a></li>
+
+  <li>Pituitary gland,
+    <a href="#Page_98">98</a></li>
+
+  <li>Placodermi,
+    <a href="#Page_351">351</a></li>
+
+  <li>Placoid scales,
+    <a href="#Page_48">48</a></li>
+
+  <li>Plagiostomata,
+    <a href="#Page_313">313</a></li>
+
+  <li>Plagiotremus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Plagusia,
+    <a href="#Page_559">559</a></li>
+
+  <li>Plagyodus,
+    <a href="#Page_586">586</a></li>
+
+  <li>Plaice,
+    <a href="#Page_557">557</a></li>
+
+  <li>Pla-kat,
+    <a href="#Page_519">519</a></li>
+
+  <li>Platax,
+    <a href="#Page_448">448</a></li>
+
+  <li>Platinx,
+    <a href="#Page_656">656</a></li>
+
+  <li>Platycephalus,
+    <a href="#Page_477">477</a></li>
+
+  <li>Platycornus,
+    <a href="#Page_421">421</a></li>
+
+  <li>Platyglossus,
+    <a href="#Page_529">529</a></li>
+
+  <li>Platynematichthys,
+    <a href="#Page_566">566</a></li>
+
+  <li>Platypoecilus,
+    <a href="#Page_618">618</a></li>
+
+  <li>Platyptera,
+    <a href="#Page_489">489</a></li>
+
+  <li>Platyrhina,
+    <a href="#Page_342">342</a></li>
+
+  <li>Platysomidæ,
+    <a href="#Page_370">370</a></li>
+
+  <li>Platystethus,
+    <a href="#Page_450">450</a></li>
+
+  <li>Platystoma,
+    <a href="#Page_568">568</a></li>
+
+  <li>Platystomatichthys,
+    <a href="#Page_568">568</a></li>
+
+  <li>Platytroctes,
+    <a href="#Page_664">664</a></li>
+
+  <li>Playfair,
+    <a href="#Page_29">29</a></li>
+
+  <li>Plecoglossus,
+    <a href="#Page_646">646</a></li>
+
+  <li>Plecostomus,
+    <a href="#Page_576">576</a></li>
+
+  <li>Plectropoma,
+    <a href="#Page_382">382</a></li>
+
+  <li>Plesiops,
+    <a href="#Page_418">418</a></li>
+
+  <li>Pleurapophyses,
+    <a href="#Page_52">52</a></li>
+
+  <li>Pleurolepidæ,
+    <a href="#Page_366">366</a></li>
+
+  <li>Pleuronectes,
+    <a href="#Page_557">557</a></li>
+
+  <li>Pleuronectidæ,
+    <a href="#Page_553">553</a></li>
+
+  <li>Pleuropholis,
+    <a href="#Page_368">368</a></li>
+
+  <li>Plinthophorus,
+    <a href="#Page_666">666</a></li>
+
+  <li>Plionemus,
+    <a href="#Page_442">442</a></li>
+
+  <li>Plotosus,
+    <a href="#Page_563">563</a></li>
+
+  <li>Podabrus,
+    <a href="#Page_480">480</a></li>
+
+  <li>Podocys,
+    <a href="#Page_421">421</a></li>
+
+  <li>Poecilia,
+    <a href="#Page_617">617</a></li>
+
+  <li>Poeciloconger,
+    <a href="#Page_674">674</a></li>
+
+  <li>Poecilopsetta,
+    <a href="#Page_557">557</a></li>
+
+  <li>Poey, F.,
+    <a href="#Page_31">31</a></li>
+
+  <li>Pogonias,
+    <a href="#Page_427">427</a></li>
+
+  <li>Poisonous fishes,
+    <a href="#Page_189">189</a></li>
+
+  <li>Poisson bleu,
+    <a href="#Page_650">650</a></li>
+
+  <li>Pollack,
+    <a href="#Page_541">541</a></li>
+
+  <li>Pollan,
+    <a href="#Page_649">649</a></li>
+
+  <li>Polyacanthus,
+    <a href="#Page_516">516</a></li>
+
+  <li>Polycaulus,
+    <a href="#Page_480">480</a></li>
+
+  <li>Polycentrus,
+    <a href="#Page_418">418</a></li>
+
+  <li>Polyipnus,
+    <a href="#Page_628">628</a></li>
+
+  <li>Polymixia,
+    <a href="#Page_423">423</a></li>
+
+  <li>Polynemus,
+    <a href="#Page_425">425</a></li>
+
+  <li>Polyodontidæ,
+    <a href="#Page_362">362</a></li>
+
+  <li>Polyprion,
+    <a href="#Page_382">382</a></li>
+
+  <li>Polypteroidei,
+    <a href="#Page_363">363</a></li>
+
+  <li>Polypterus,
+    <a href="#Page_364">364</a></li>
+
+  <li>Polyrhizodus,
+    <a href="#Page_330">330</a></li>
+
+  <li>Pomacanthus,
+    <a href="#Page_401">401</a></li>
+
+  <li>Pomacentrus,
+    <a href="#Page_525">525</a></li>
+
+  <li>Pomatomus,
+    <a href="#Page_395">395</a></li>
+
+  <li>Pomotis,
+    <a href="#Page_396">396</a></li>
+
+  <li>Pompilus,
+    <a href="#Page_444">444</a></li>
+
+  <li>Pope,
+    <a href="#Page_378">378</a></li>
+
+  <li>Porbeagle,
+    <a href="#Page_320">320</a></li>
+
+  <li>Porgy,
+    <a href="#Page_408">408</a></li>
+
+  <li>Porichthys,
+    <a href="#Page_468">468</a></li>
+
+  <li>Portheus,
+    <a href="#Page_500">500</a></li>
+
+  <li>Porthmeus,
+    <a href="#Page_446">446</a></li>
+
+  <li>Port Jackson Shark,
+    <a href="#Page_330">330</a></li>
+
+  <li>Porus abdominalis,
+    <a href="#Page_123">123</a></li>
+
+  <li>Porus genitalis,
+    <a href="#Page_123">123</a>,
+    <a href="#Page_158">158</a></li>
+
+  <li>Postclavicula,
+    <a href="#Page_59">59</a>,
+    <a href="#Page_92">92</a></li>
+
+  <li>Postfrontal bone,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Post-pliocene fishes,
+    <a href="#Page_201">201</a></li>
+
+  <li>Post-temporal,
+    <a href="#Page_59">59</a>,
+    <a href="#Page_92">92</a></li>
+
+  <li>Pout,
+    <a href="#Page_541">541</a></li>
+
+  <li>Powen,
+    <a href="#Page_649">649</a></li>
+
+  <li>Præoperculum,
+    <a href="#Page_38">38</a>,
+    <a href="#Page_54">54</a>,
+    <a href="#Page_90">90</a></li>
+
+  <li>Præorbital,
+    <a href="#Page_54">54</a></li>
+
+  <li>Prefrontal,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Premaxillary,
+    <a href="#Page_53">53</a>,
+    <a href="#Page_90">90</a></li>
+
+  <li>Premnas,
+    <a href="#Page_525">525</a></li>
+
+  <li>Preñadillas,
+    <a href="#Page_575">575</a></li>
+
+  <li>Pretympanic,
+    <a href="#Page_55">55</a></li>
+
+  <li>Priacanthus,
+    <a href="#Page_395">395</a></li>
+
+  <li>Pride,
+    <a href="#Page_693">693</a></li>
+
+  <li>Prionotus,
+    <a href="#Page_479">479</a></li>
+
+  <li>Prionurus,
+    <a href="#Page_440">440</a></li>
+
+  <li>Pristacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Pristidæ,
+    <a href="#Page_336">336</a></li>
+
+  <li>Pristigaster,
+    <a href="#Page_660">660</a></li>
+
+  <li>Pristiophorus,
+    <a href="#Page_335">335</a></li>
+
+  <li>Pristipoma,
+    <a href="#Page_385">385</a></li>
+
+  <li>Pristis,
+    <a href="#Page_337">337</a></li>
+
+  <li>Pristiurus,
+    <a href="#Page_326">326</a></li>
+
+  <li>Prochilodus,
+    <a href="#Page_607">607</a></li>
+
+  <li>Prooticum,
+    <a href="#Page_88">88</a></li>
+
+  <li>Propterus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Propterygium,
+    <a href="#Page_70">70</a></li>
+
+  <li>Prosencephalon,
+    <a href="#Page_97">97</a></li>
+
+  <li>Prosopodasys,
+    <a href="#Page_417">417</a></li>
+
+  <li>Protamia,
+    <a href="#Page_372">372</a></li>
+
+  <li>Protocampus,
+    <a href="#Page_681">681</a></li>
+
+  <li>Protopterus,
+    <a href="#Page_356">356</a></li>
+
+  <li>Protosphyræna,
+    <a href="#Page_500">500</a></li>
+
+  <li>Prototroctes,
+    <a href="#Page_652">652</a></li>
+
+  <li>Prussian carp,
+    <a href="#Page_591">591</a></li>
+
+  <li>Psaliodus,
+    <a href="#Page_349">349</a></li>
+
+  <li>Psammobatis,
+    <a href="#Page_342">342</a></li>
+
+  <li>Psammodiscus,
+    <a href="#Page_557">557</a></li>
+
+  <li>Psammodus,
+    <a href="#Page_329">329</a></li>
+
+  <li>Psammoperca,
+    <a href="#Page_378">378</a></li>
+
+  <li>Psenes,
+    <a href="#Page_456">456</a></li>
+
+  <li>Psephurus,
+    <a href="#Page_363">363</a></li>
+
+  <li>Psettichthys,
+    <a href="#Page_556">556</a></li>
+
+  <li>Psettodes,
+    <a href="#Page_554">554</a></li>
+
+  <li>Psettus,
+    <a href="#Page_447">447</a></li>
+
+  <li>Pseudecheneis,
+    <a href="#Page_580">580</a></li>
+
+  <li>Pseudeutropius,
+    <a href="#Page_566">566</a></li>
+
+  <li>Pseudobagrus,
+    <a href="#Page_567">567</a></li>
+
+  <li>Pseudoberyx,
+    <a href="#Page_421">421</a></li>
+
+  <li>Pseudoblennius,
+    <a href="#Page_498">498</a></li>
+
+  <li>Pseudobranchiæ,
+    <a href="#Page_140">140</a></li>
+
+  <li>Pseudochalceus,
+    <a href="#Page_610">610</a></li>
+
+  <li>Pseudochilinus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Pseudochromis,
+    <a href="#Page_466">466</a></li>
+
+  <li>Pseudodax,
+    <a href="#Page_530">530</a></li>
+
+  <li>Pseudoeleginus,
+    <a href="#Page_462">462</a></li>
+
+  <li>Pseudogobio,
+    <a href="#Page_596">596</a></li>
+
+  <li>Pseudojulis,
+    <a href="#Page_529">529</a></li>
+
+  <li>Pseudolabuca,
+    <a href="#Page_604">604</a></li>
+
+  <li>Pseudoperilampus,
+    <a href="#Page_601">601</a></li>
+
+  <li>Pseudophycis,
+    <a href="#Page_542">542</a></li>
+
+  <li>Pseudoplesiops,
+    <a href="#Page_466">466</a></li>
+
+  <li>Pseudorasbora,
+    <a href="#Page_596">596</a></li>
+
+  <li>Pseudorhombus,
+    <a href="#Page_556">556</a></li>
+
+  <li>Pseudoscarus,
+    <a href="#Page_532">532</a></li>
+
+  <li>Pseudosyngnathus,
+    <a href="#Page_680">680</a></li>
+
+  <li>Pseudovomer,
+    <a href="#Page_442">442</a></li>
+
+  <li>Pseudoxiphophorus,
+    <a href="#Page_617">617</a></li>
+
+  <li>Psilorhynchus,
+    <a href="#Page_604">604</a></li>
+
+  <li>Psychrolutes,
+    <a href="#Page_469">469</a></li>
+
+  <li>Pteraclis,
+    <a href="#Page_455">455</a></li>
+
+  <li>Pteragogus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Pteraspis,
+    <a href="#Page_354">354</a></li>
+
+  <li>Pterichthys,
+    <a href="#Page_351">351</a></li>
+
+  <li>Pteroplatea,
+    <a href="#Page_344">344</a></li>
+
+  <li>Pteridium,
+    <a href="#Page_549">549</a></li>
+
+  <li>Pterois,
+    <a href="#Page_415">415</a></li>
+
+  <li>Pterophyllum,
+    <a href="#Page_537">537</a></li>
+
+  <li>Pteropsarion,
+    <a href="#Page_602">602</a></li>
+
+  <li>Pterygocephalus,
+    <a href="#Page_492">492</a></li>
+
+  <li>Pterygoid,
+    <a href="#Page_56">56</a></li>
+
+  <li>Pterygoplichthys,
+    <a href="#Page_576">576</a></li>
+
+  <li>Ptychacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Ptychobarbus,
+    <a href="#Page_595">595</a></li>
+
+  <li>Ptychodus,
+    <a href="#Page_330">330</a></li>
+
+  <li>Ptycholepis,
+    <a href="#Page_368">368</a></li>
+
+  <li>Ptyonotus,
+    <a href="#Page_480">480</a></li>
+
+  <li>Pycnodontidæ,
+    <a href="#Page_366">366</a></li>
+
+  <li>Pygopterus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Pyloric appendages,
+    <a href="#Page_131">131</a></li>
+
+  <li>Pyrrhulina,
+    <a href="#Page_607">607</a></li>
+</ul>
+
+ <ul>
+  <li>Quadrate Bone,
+    <a href="#Page_55">55</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Quoy et Gaimard,
+    <a href="#Page_26">26</a></li>
+</ul>
+
+<ul>
+  <li>Radius,
+    <a href="#Page_59">59</a></li>
+
+  <li>Raja,
+    <a href="#Page_340">340</a></li>
+
+  <li>Raniceps,
+    <a href="#Page_544">544</a></li>
+
+  <li>Rasbora,
+    <a href="#Page_597">597</a></li>
+
+  <li>Rasborichthys,
+    <a href="#Page_604">604</a></li>
+
+  <li>Rathke,
+    <a href="#Page_32">32</a></li>
+
+  <li>Ray,
+    <a href="#Page_8">8</a></li>
+
+  <li>Rays of fins,
+    <a href="#Page_40">40</a></li>
+
+  <li>Rays,
+    <a href="#Page_335">335</a>,
+    <a href="#Page_341">341</a></li>
+
+  <li>Red bodies,
+    <a href="#Page_147">147</a></li>
+
+  <li>Red-dace,
+    <a href="#Page_599">599</a></li>
+
+  <li>Red-eye,
+    <a href="#Page_599">599</a></li>
+
+  <li>Red-fin,
+    <a href="#Page_599">599</a></li>
+
+  <li>Red-horse,
+    <a href="#Page_589">589</a></li>
+
+  <li>Red mullet,
+    <a href="#Page_404">404</a></li>
+
+  <li>Regalecus,
+    <a href="#Page_522">522</a></li>
+
+  <li>Reproduction of lost parts,
+    <a href="#Page_188">188</a></li>
+
+  <li>Reproduction, organs of,
+    <a href="#Page_157">157</a></li>
+
+  <li>Respiration, organs of,
+    <a href="#Page_135">135</a></li>
+
+  <li>Rete mirabile,
+    <a href="#Page_147">147</a></li>
+
+  <li>Retropinna,
+    <a href="#Page_647">647</a></li>
+
+  <li>Retzius,
+    <a href="#Page_32">32</a></li>
+
+  <li>Rhabdolepis,
+    <a href="#Page_370">370</a></li>
+
+  <li>Rhacolepis,
+    <a href="#Page_421">421</a></li>
+
+  <li>Rhadinichthys,
+    <a href="#Page_370">370</a></li>
+
+  <li>Rhamphichthys,
+    <a href="#Page_666">666</a></li>
+
+  <li>Rhamphocottus,
+    <a href="#Page_480">480</a></li>
+
+  <li>Rhamphosus,
+    <a href="#Page_507">507</a></li>
+
+  <li>Rhina,
+    <a href="#Page_334">334</a></li>
+
+  <li>Rhinelepis,
+    <a href="#Page_576">576</a></li>
+
+  <li>Rhinellus,
+    <a href="#Page_656">656</a></li>
+
+  <li>Rhinichthys,
+    <a href="#Page_596">596</a></li>
+
+  <li>Rhinobatus,
+    <a href="#Page_338">338</a></li>
+
+  <li>Rhinodon,
+    <a href="#Page_323">323</a></li>
+
+  <li>Rhinodoras,
+    <a href="#Page_572">572</a></li>
+
+  <li>Rhinoglanis,
+    <a href="#Page_573">573</a></li>
+
+  <li>Rhinonus,
+    <a href="#Page_549">549</a></li>
+
+  <li>Rhinoptera,
+    <a href="#Page_346">346</a></li>
+
+  <li>Rhizodus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Rhodeus,
+    <a href="#Page_601">601</a></li>
+
+  <li>Rhomboidichthys,
+    <a href="#Page_556">556</a></li>
+
+  <li>Rhombosolea,
+    <a href="#Page_557">557</a></li>
+
+  <li>Rhombus,
+    <a href="#Page_555">555</a></li>
+
+  <li>Rhynchichthys,
+    <a href="#Page_424">424</a></li>
+
+  <li>Rhynchobatus,
+    <a href="#Page_337">337</a></li>
+
+  <li>Rhynchobdella,
+    <a href="#Page_498">498</a></li>
+
+  <li>Rhynchodus,
+    <a href="#Page_349">349</a></li>
+
+  <li>Rhypticus,
+    <a href="#Page_383">383</a></li>
+
+  <li>Rhytiodus,
+    <a href="#Page_608">608</a></li>
+
+  <li>Rib,
+    <a href="#Page_52">52</a></li>
+
+  <li>Ribbon-fishes,
+    <a href="#Page_520">520</a></li>
+
+  <li>Richardson,
+    <a href="#Page_27">27</a>,
+    <a href="#Page_28">28</a></li>
+
+  <li>Risso,
+    <a href="#Page_17">17</a></li>
+
+  <li>Rita,
+    <a href="#Page_567">567</a></li>
+
+  <li>Rivulus,
+    <a href="#Page_615">615</a></li>
+
+  <li>Roach,
+    <a href="#Page_599">599</a>,
+    <a href="#Page_600">600</a></li>
+
+  <li>Rock-cook,
+    <a href="#Page_528">528</a></li>
+
+  <li>Rockling,
+    <a href="#Page_544">544</a></li>
+
+  <li>Rohteichthys,
+    <a href="#Page_597">597</a></li>
+
+  <li>Rondelet,
+    <a href="#Page_5">5</a></li>
+
+  <li>Rosenthal,
+    <a href="#Page_32">32</a></li>
+
+  <li>Rough Dab,
+    <a href="#Page_555">555</a></li>
+
+  <li>Rudd,
+    <a href="#Page_599">599</a></li>
+
+  <li>Rüppell,
+    <a href="#Page_29">29</a></li>
+
+  <li>Russel,
+    <a href="#Page_16">16</a></li>
+</ul>
+
+<ul>
+  <li>Saccarius,
+    <a href="#Page_474">474</a></li>
+
+  <li>Saccobranchus,
+    <a href="#Page_565">565</a></li>
+
+  <li>Saccodon,
+    <a href="#Page_607">607</a></li>
+
+  <li>Saccopharynx,
+    <a href="#Page_670">670</a></li>
+
+  <li>Sælbling,
+    <a href="#Page_645">645</a></li>
+
+  <li>Sail-fish,
+    <a href="#Page_589">589</a></li>
+
+  <li>Sail-fluke,
+    <a href="#Page_555">555</a></li>
+
+  <li>Salanx,
+    <a href="#Page_650">650</a></li>
+
+  <li>Salarias,
+    <a href="#Page_494">494</a></li>
+
+  <li>Salivary glands,
+    <a href="#Page_124">124</a></li>
+
+  <li>Salminus,
+    <a href="#Page_611">611</a></li>
+
+  <li>Salmo,
+    <a href="#Page_631">631</a></li>
+
+  <li>Salmon,
+    <a href="#Page_644">644</a></li>
+
+  <li>Salmon-trout,
+    <a href="#Page_644">644</a></li>
+
+  <li>Salvelini,
+    <a href="#Page_645">645</a></li>
+
+  <li>Salviani,
+    <a href="#Page_5">5</a></li>
+
+  <li>Samaris,
+    <a href="#Page_556">556</a></li>
+
+  <li>Sand-eel,
+    <a href="#Page_550">550</a></li>
+
+  <li>Sand-piper,
+    <a href="#Page_693">693</a></li>
+
+  <li>Sandy Ray,
+    <a href="#Page_341">341</a></li>
+
+  <li>Sar,
+    <a href="#Page_406">406</a></li>
+
+  <li>Saragu,
+    <a href="#Page_406">406</a></li>
+
+  <li>Sarcodaces,
+    <a href="#Page_611">611</a></li>
+
+  <li>Sardine,
+    <a href="#Page_660">660</a></li>
+
+  <li>Sargina,
+    <a href="#Page_406">406</a></li>
+
+  <li>Sargo,
+    <a href="#Page_406">406</a></li>
+
+  <li>Sargodon,
+    <a href="#Page_405">405</a></li>
+
+  <li>Sargus,
+    <a href="#Page_406">406</a></li>
+
+  <li>Satanoperca,
+    <a href="#Page_537">537</a></li>
+
+  <li>Saurenchelys,
+    <a href="#Page_674">674</a></li>
+
+  <li>Saurichthys,
+    <a href="#Page_365">365</a></li>
+
+  <li>Saurida,
+    <a href="#Page_582">582</a></li>
+
+  <li>Sauridæ,
+    <a href="#Page_368">368</a></li>
+
+  <li>Saurocephalus,
+    <a href="#Page_500">500</a></li>
+
+  <li>Saurodipteridæ,
+    <a href="#Page_355">355</a></li>
+
+  <li>Saurodontidæ,
+    <a href="#Page_500">500</a></li>
+
+  <li>Saurorhamphus,
+    <a href="#Page_666">666</a></li>
+
+  <li>Saurus,
+    <a href="#Page_582">582</a></li>
+
+  <li>Saury,
+    <a href="#Page_620">620</a></li>
+
+  <li>Saw-fishes,
+    <a href="#Page_337">337</a></li>
+
+  <li>Scabbard-fish,
+    <a href="#Page_435">435</a></li>
+
+  <li>Scald-fish,
+    <a href="#Page_556">556</a></li>
+
+  <li>Scales,
+    <a href="#Page_45">45</a></li>
+
+  <li>Scaphaspis,
+    <a href="#Page_354">354</a></li>
+
+  <li>Scaphirhynchus,
+    <a href="#Page_362">362</a></li>
+
+  <li>Scapula,
+    <a href="#Page_59">59</a>,
+    <a href="#Page_92">92</a></li>
+
+  <li>Scapular arch,
+    <a href="#Page_59">59</a></li>
+
+  <li>Scarichthys,
+    <a href="#Page_531">531</a></li>
+
+  <li>Scarus,
+    <a href="#Page_526">526</a>,
+    <a href="#Page_530">530</a></li>
+
+  <li>Scatharus,
+    <a href="#Page_406">406</a></li>
+
+  <li>Scatophagus,
+    <a href="#Page_401">401</a></li>
+
+  <li>Schacra,
+    <a href="#Page_602">602</a></li>
+
+  <li>Schal,
+    <a href="#Page_573">573</a></li>
+
+  <li>Schedophilus,
+    <a href="#Page_455">455</a></li>
+
+  <li>Schell-fisch,
+    <a href="#Page_540">540</a></li>
+
+  <li>Schelly,
+    <a href="#Page_649">649</a></li>
+
+  <li>Schilbe,
+    <a href="#Page_566">566</a></li>
+
+  <li>Schilbichthys,
+    <a href="#Page_566">566</a></li>
+
+  <li>Schizopygopsis,
+    <a href="#Page_595">595</a></li>
+
+  <li>Schizothorax,
+    <a href="#Page_595">595</a></li>
+
+  <li>Schlegel,
+    <a href="#Page_29">29</a></li>
+
+  <li>Schneider,
+    <a href="#Page_15">15</a></li>
+
+  <li>Schultze,
+    <a href="#Page_33">33</a></li>
+
+  <li>Sciades,
+    <a href="#Page_568">568</a></li>
+
+  <li>Sciæna,
+    <a href="#Page_429">429</a></li>
+
+  <li>Sciænidæ,
+    <a href="#Page_426">426</a></li>
+
+  <li>Scissor,
+    <a href="#Page_610">610</a></li>
+
+  <li>Sclerodermi,
+    <a href="#Page_684">684</a></li>
+
+  <li>Sclerognathus,
+    <a href="#Page_589">589</a></li>
+
+  <li>Scolopsis,
+    <a href="#Page_389">389</a></li>
+
+  <li>Scomber,
+    <a href="#Page_457">457</a></li>
+
+  <li>Scombresox,
+    <a href="#Page_620">620</a></li>
+
+  <li>Scombridæ,
+    <a href="#Page_456">456</a></li>
+
+  <li>Scombroclupea,
+    <a href="#Page_656">656</a></li>
+
+  <li>Scombrops,
+    <a href="#Page_395">395</a></li>
+
+  <li>Scopelidæ,
+    <a href="#Page_582">582</a></li>
+
+  <li>Scopelosaurus,
+    <a href="#Page_587">587</a></li>
+
+  <li>Scopelus,
+    <a href="#Page_584">584</a></li>
+
+  <li>Scorpæna,
+    <a href="#Page_444">444</a></li>
+
+  <li>Scorpænichthys,
+    <a href="#Page_480">480</a></li>
+
+  <li>Scorpænidæ,
+    <a href="#Page_412">412</a></li>
+
+  <li>Scorpis,
+    <a href="#Page_402">402</a></li>
+
+  <li>Scup,
+    <a href="#Page_408">408</a></li>
+
+  <li>Scylliodus,
+    <a href="#Page_326">326</a></li>
+
+  <li>Scyllium,
+    <a href="#Page_325">325</a></li>
+
+  <li>Scymnus,
+    <a href="#Page_332">332</a></li>
+
+  <li>Sea-bat,
+    <a href="#Page_448">448</a></li>
+
+  <li>Sea-bream,
+    <a href="#Page_405">405</a>,
+    <a href="#Page_408">408</a></li>
+
+  <li>Sea-cat,
+    <a href="#Page_493">493</a></li>
+
+  <li>Sea-devil,
+    <a href="#Page_344">344</a>,
+    <a href="#Page_470">470</a></li>
+
+  <li>Sea-hedgehog,
+    <a href="#Page_687">687</a></li>
+
+  <li>Sea-horses,
+    <a href="#Page_682">682</a></li>
+
+  <li>Sea-perch,
+    <a href="#Page_381">381</a></li>
+
+  <li>Sea-serpents,
+    <a href="#Page_521">521</a></li>
+
+  <li>Sea-trout,
+    <a href="#Page_644">644</a></li>
+
+  <li>Sea-wolf,
+    <a href="#Page_493">493</a></li>
+
+  <li>Seba,
+    <a href="#Page_9">9</a></li>
+
+  <li>Sebastes,
+    <a href="#Page_413">413</a></li>
+
+  <li>Secondary sexual characters,
+    <a href="#Page_176">176</a></li>
+
+  <li>Seingo,
+    <a href="#Page_378">378</a></li>
+
+  <li>Selache,
+    <a href="#Page_322">322</a></li>
+
+  <li>Selachoidei,
+    <a href="#Page_314">314</a></li>
+
+  <li>Semicossyphus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Semionotus,
+    <a href="#Page_368">368</a></li>
+
+  <li>Semiophorus,
+    <a href="#Page_441">441</a>,
+    <a href="#Page_442">442</a></li>
+
+  <li>Semiplotus,
+    <a href="#Page_598">598</a></li>
+
+  <li>Seriola,
+    <a href="#Page_444">444</a></li>
+
+  <li>Seriolella,
+    <a href="#Page_444">444</a>,
+    <a href="#Page_450">450</a></li>
+
+  <li>Seriolichthys,
+    <a href="#Page_444">444</a></li>
+
+  <li>Serranus,
+    <a href="#Page_381">381</a></li>
+
+  <li>Serrasalmo,
+    <a href="#Page_613">613</a></li>
+
+  <li>Setiform teeth,
+    <a href="#Page_126">126</a></li>
+
+  <li>Sewin,
+    <a href="#Page_644">644</a></li>
+
+  <li>Sexual characters,
+    <a href="#Page_176">176</a></li>
+
+  <li>Shad,
+    <a href="#Page_659">659</a></li>
+
+  <li>Shagreen,
+    <a href="#Page_315">315</a></li>
+
+  <li>Shagreen Skate,
+    <a href="#Page_341">341</a></li>
+
+  <li>Sharks,
+    <a href="#Page_314">314</a></li>
+
+  <li>Shark’s fins,
+    <a href="#Page_315">315</a></li>
+
+  <li>Sheep’s head,
+    <a href="#Page_406">406</a></li>
+
+  <li>Shiner,
+    <a href="#Page_599">599</a>,
+    <a href="#Page_603">603</a></li>
+
+  <li>Shore-fishes,
+    <a href="#Page_257">257</a></li>
+
+  <li>Sicyases,
+    <a href="#Page_513">513</a></li>
+
+  <li>Sicydium,
+    <a href="#Page_487">487</a></li>
+
+  <li>Siebold,
+    <a href="#Page_28">28</a></li>
+
+  <li>Sillago,
+    <a href="#Page_464">464</a></li>
+
+  <li>Silondia,
+    <a href="#Page_566">566</a></li>
+
+  <li>Siluranodon,
+    <a href="#Page_566">566</a></li>
+
+  <li>Silurian fishes,
+    <a href="#Page_193">193</a></li>
+
+  <li>Silurichthys,
+    <a href="#Page_566">566</a></li>
+
+  <li>Siluridæ,
+    <a href="#Page_559">559</a></li>
+
+  <li>Siluris,
+    <a href="#Page_565">565</a></li>
+
+  <li>Siniperca,
+    <a href="#Page_376">376</a></li>
+
+  <li>Sinus rhomboidalis,
+    <a href="#Page_99">99</a></li>
+
+  <li>Siphagonus,
+    <a href="#Page_481">481</a></li>
+
+  <li>Siphonal stomach,
+    <a href="#Page_130">130</a></li>
+
+  <li>Siphonognathus,
+    <a href="#Page_533">533</a></li>
+
+  <li>Siphonostoma,
+    <a href="#Page_680">680</a></li>
+
+  <li>Sirembo,
+    <a href="#Page_549">549</a></li>
+
+  <li>Sirenidæ,
+    <a href="#Page_355">355</a></li>
+
+  <li>Sisor,
+    <a href="#Page_580">580</a></li>
+
+  <li>Skate,
+    <a href="#Page_341">341</a></li>
+
+  <li>Skeleton of—</li>
+  <li class="i1">Amia,
+    <a href="#Page_82">82</a></li>
+  <li class="i1">Amphioxus,
+    <a href="#Page_63">63</a></li>
+  <li class="i1">Chondropterygians,
+    <a href="#Page_66">66</a></li>
+  <li class="i1">Chondrostei,
+    <a href="#Page_74">74</a></li>
+  <li class="i1">Cyclostomes,
+    <a href="#Page_64">64</a></li>
+  <li class="i1">Dipnoi,
+    <a href="#Page_71">71</a></li>
+  <li class="i1">Ganoids,
+    <a href="#Page_71">71</a></li>
+  <li class="i1">Lepidosteus,
+    <a href="#Page_80">80</a></li>
+  <li class="i1">Polypterus,
+    <a href="#Page_77">77</a></li>
+  <li class="i1">Teleostei,
+    <a href="#Page_83">83</a></li>
+
+  <li>Skin,
+    <a href="#Page_45">45</a></li>
+
+  <li>Skip-jack,
+    <a href="#Page_447">447</a></li>
+
+  <li>Skipper,
+    <a href="#Page_620">620</a></li>
+
+  <li>Skull,
+    <a href="#Page_51">51</a>,
+    <a href="#Page_85">85</a></li>
+
+  <li>Skulpin,
+    <a href="#Page_489">489</a></li>
+
+  <li>Smaris,
+    <a href="#Page_390">390</a></li>
+
+  <li>Smear-dab,
+    <a href="#Page_557">557</a></li>
+
+  <li>Smelt,
+    <a href="#Page_647">647</a></li>
+
+  <li>Smerdis,
+    <a href="#Page_375">375</a></li>
+
+  <li>Smiliogaster,
+    <a href="#Page_604">604</a></li>
+
+  <li>Snapper,
+    <a href="#Page_408">408</a></li>
+
+  <li>Snock,
+    <a href="#Page_437">437</a></li>
+
+  <li>Snout,
+    <a href="#Page_37">37</a></li>
+
+  <li>Solander,
+    <a href="#Page_13">13</a></li>
+
+  <li>Sole,
+    <a href="#Page_557">557</a></li>
+
+  <li>Solea,
+    <a href="#Page_557">557</a></li>
+
+  <li>Solenognathus,
+    <a href="#Page_682">682</a></li>
+
+  <li>Solenorhynchus,
+    <a href="#Page_678">678</a></li>
+
+  <li>Solenostoma,
+    <a href="#Page_678">678</a></li>
+
+  <li>Soleotalpa,
+    <a href="#Page_559">559</a></li>
+
+  <li>Sonnerat,
+    <a href="#Page_13">13</a></li>
+
+  <li>Soricidens,
+    <a href="#Page_405">405</a></li>
+
+  <li>Sorubim,
+    <a href="#Page_568">568</a></li>
+
+  <li>South Australian district,
+    <a href="#Page_283">283</a></li>
+
+  <li>Southern temperate zone,
+    <a href="#Page_281">281</a></li>
+
+  <li>Southern zone,
+    <a href="#Page_248">248</a></li>
+
+  <li>Spaniodon,
+    <a href="#Page_656">656</a></li>
+
+  <li>Sparidæ,
+    <a href="#Page_405">405</a></li>
+
+  <li>Sparnodus,
+    <a href="#Page_405">405</a></li>
+
+  <li>Sparoid scales,
+    <a href="#Page_46">46</a></li>
+
+  <li>Spathobatis,
+    <a href="#Page_338">338</a></li>
+
+  <li>Spathodactylus,
+    <a href="#Page_656">656</a></li>
+
+  <li>Spatularia,
+    <a href="#Page_362">362</a></li>
+
+  <li>Spawn-eater,
+    <a href="#Page_599">599</a></li>
+
+  <li>Spear-fish,
+    <a href="#Page_589">589</a></li>
+
+  <li>Sphærodon,
+    <a href="#Page_408">408</a></li>
+
+  <li>Sphærodontidæ,
+    <a href="#Page_368">368</a></li>
+
+  <li>Sphenacanthus,
+    <a href="#Page_314">314</a></li>
+
+  <li>Sphenocephalus,
+    <a href="#Page_421">421</a></li>
+
+  <li>Sphenodus,
+    <a href="#Page_319">319</a></li>
+
+  <li>Sphenoid,
+    <a href="#Page_57">57</a></li>
+
+  <li>Sphenoideum anterius,
+    <a href="#Page_89">89</a></li>
+
+  <li>Sphyræna,
+    <a href="#Page_499">499</a></li>
+
+  <li>Sphyrænodus,
+    <a href="#Page_500">500</a></li>
+
+  <li>Spiegel-Karpfen,
+    <a href="#Page_591">591</a></li>
+
+  <li>Spinacidæ,
+    <a href="#Page_330">330</a></li>
+
+  <li>Spinal chord,
+    <a href="#Page_96">96</a></li>
+
+  <li>Spinal column,
+    <a href="#Page_51">51</a></li>
+
+  <li>Spinax,
+    <a href="#Page_332">332</a></li>
+
+  <li>Spines of fins,
+    <a href="#Page_40">40</a></li>
+
+  <li>Spiracles,
+    <a href="#Page_138">138</a></li>
+
+  <li>Spiral valve,
+    <a href="#Page_128">128</a></li>
+
+  <li>Spirobranchus,
+    <a href="#Page_516">516</a></li>
+
+  <li>Splanchnoskeleton,
+    <a href="#Page_85">85</a></li>
+
+  <li>Spleen,
+    <a href="#Page_133">133</a></li>
+
+  <li>Splenial,
+    <a href="#Page_54">54</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Sprat,
+    <a href="#Page_659">659</a></li>
+
+  <li>Spratelloides,
+    <a href="#Page_662">662</a></li>
+
+  <li>Squaliobarbus,
+    <a href="#Page_602">602</a></li>
+
+  <li>Squaloraja,
+    <a href="#Page_335">335</a></li>
+
+  <li>Squamipinnes,
+    <a href="#Page_397">397</a></li>
+
+  <li>Squamosal,
+    <a href="#Page_88">88</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Stannius,
+    <a href="#Page_32">32</a>,
+    <a href="#Page_33">33</a></li>
+
+  <li>Stare-gazer,
+    <a href="#Page_462">462</a></li>
+
+  <li>Starry Ray,
+    <a href="#Page_341">341</a></li>
+
+  <li>Stegophilus,
+    <a href="#Page_581">581</a></li>
+
+  <li>Stegostoma,
+    <a href="#Page_326">326</a></li>
+
+  <li>Steindachner,
+    <a href="#Page_28">28</a></li>
+
+  <li>Steller,
+    <a href="#Page_13">13</a></li>
+
+  <li>Stenostoma,
+    <a href="#Page_421">421</a></li>
+
+  <li>Sterlet,
+    <a href="#Page_361">361</a></li>
+
+  <li>Sternarchus,
+    <a href="#Page_666">666</a></li>
+
+  <li>Sternoptyx,
+    <a href="#Page_627">627</a></li>
+
+  <li>Sternopygus,
+    <a href="#Page_667">667</a></li>
+
+  <li>Stethojulis,
+    <a href="#Page_529">529</a></li>
+
+  <li>Stichæopsis,
+    <a href="#Page_498">498</a></li>
+
+  <li>Stichæus,
+    <a href="#Page_495">495</a></li>
+
+  <li>Sticharium,
+    <a href="#Page_498">498</a></li>
+
+  <li>Stickleback,
+    <a href="#Page_505">505</a></li>
+
+  <li>Stigmatophora,
+    <a href="#Page_681">681</a></li>
+
+  <li>Sting Rays,
+    <a href="#Page_342">342</a></li>
+
+  <li>Stock-fish,
+    <a href="#Page_540">540</a>,
+    <a href="#Page_542">542</a></li>
+
+  <li>Stomach,
+    <a href="#Page_127">127</a></li>
+
+  <li>Stomias,
+    <a href="#Page_629">629</a></li>
+
+  <li>Stone-bass,
+    <a href="#Page_382">382</a></li>
+
+  <li>Stone-lugger,
+    <a href="#Page_596">596</a></li>
+
+  <li>Stone-roller,
+    <a href="#Page_589">589</a></li>
+
+  <li>Stone Toter,
+    <a href="#Page_596">596</a></li>
+
+  <li>Storer,
+    <a href="#Page_29">29</a></li>
+
+  <li>Strepsodus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Strinsia,
+    <a href="#Page_541">541</a></li>
+
+  <li>Stromateus,
+    <a href="#Page_452">452</a></li>
+
+  <li>Strophodus,
+    <a href="#Page_330">330</a></li>
+
+  <li>Sturgeons,
+    <a href="#Page_361">361</a></li>
+
+  <li>Stygogenes,
+    <a href="#Page_575">575</a></li>
+
+  <li>Stylodontidæ,
+    <a href="#Page_368">368</a></li>
+
+  <li>Stylohyal,
+    <a href="#Page_58">58</a></li>
+
+  <li>Stylophorus,
+    <a href="#Page_522">522</a></li>
+
+  <li>Suboperculum,
+    <a href="#Page_38">38</a>,
+    <a href="#Page_55">55</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Suborbital,
+    <a href="#Page_91">91</a></li>
+
+  <li>Sucker,
+    <a href="#Page_588">588</a></li>
+
+  <li>Sucking-fish,
+    <a href="#Page_460">460</a></li>
+
+  <li>Sudis,
+    <a href="#Page_586">586</a></li>
+
+  <li>Sun-fishes,
+    <a href="#Page_396">396</a>,
+    <a href="#Page_454">454</a>,
+    <a href="#Page_690">690</a></li>
+
+  <li>Supraclavicula,
+    <a href="#Page_59">59</a>,
+    <a href="#Page_92">92</a></li>
+
+  <li>Supraoccipital,
+    <a href="#Page_56">56</a>,
+    <a href="#Page_87">87</a></li>
+
+  <li>Supraorbital,
+    <a href="#Page_89">89</a></li>
+
+  <li>Suprascapula,
+    <a href="#Page_59">59</a></li>
+
+  <li>Supratemporal,
+    <a href="#Page_91">91</a></li>
+
+  <li>Surgeon,
+    <a href="#Page_439">439</a></li>
+
+  <li>Suspensorium of mandible,
+    <a href="#Page_55">55</a></li>
+
+  <li>Swammerdam,
+    <a href="#Page_7">7</a></li>
+
+  <li>Sword-fish,
+    <a href="#Page_431">431</a></li>
+
+  <li>Symbranchus,
+    <a href="#Page_669">669</a></li>
+
+  <li>Sympathic nerves,
+    <a href="#Page_108">108</a></li>
+
+  <li>Symphorus,
+    <a href="#Page_390">390</a></li>
+
+  <li>Symphysis,
+    <a href="#Page_54">54</a></li>
+
+  <li>Symphysodon,
+    <a href="#Page_537">537</a></li>
+
+  <li>Symplectic,
+    <a href="#Page_55">55</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Sympterygia,
+    <a href="#Page_342">342</a></li>
+
+  <li>Synagris,
+    <a href="#Page_390">390</a></li>
+
+  <li>Synanceia,
+    <a href="#Page_416">416</a></li>
+
+  <li>Synaphobranchus,
+    <a href="#Page_671">671</a></li>
+
+  <li>Synaptura,
+    <a href="#Page_558">558</a></li>
+
+  <li>Syngnathus,
+    <a href="#Page_680">680</a></li>
+
+  <li>Synodontis,
+    <a href="#Page_573">573</a></li>
+</ul>
+
+<ul>
+  <li>Taenianotus,
+    <a href="#Page_417">417</a></li>
+
+  <li>Taeniura,
+    <a href="#Page_343">343</a></li>
+
+  <li>Taractes,
+    <a href="#Page_454">454</a></li>
+
+  <li>Tasmanian sub-region,
+    <a href="#Page_248">248</a></li>
+
+  <li>Taste, organ of,
+    <a href="#Page_119">119</a></li>
+
+  <li>Taurinichthys,
+    <a href="#Page_526">526</a></li>
+
+  <li>Tautoga,
+    <a href="#Page_527">527</a></li>
+
+  <li>Teeth,
+    <a href="#Page_121">121</a>,
+    <a href="#Page_124">124</a></li>
+
+  <li>Teleostei,
+    <a href="#Page_373">373</a></li>
+
+  <li>Telescope-fish,
+    <a href="#Page_592">592</a></li>
+
+  <li>Tellia,
+    <a href="#Page_615">615</a></li>
+
+  <li>Temera,
+    <a href="#Page_340">340</a></li>
+
+  <li>Temnodon,
+    <a href="#Page_446">446</a></li>
+
+  <li>Tenacity of life,
+    <a href="#Page_186">186</a></li>
+
+  <li>Tench,
+    <a href="#Page_600">600</a></li>
+
+  <li>Tephraeops,
+    <a href="#Page_406">406</a></li>
+
+  <li>Tephritis,
+    <a href="#Page_555">555</a></li>
+
+  <li>Tertiary fishes,
+    <a href="#Page_200">200</a></li>
+
+  <li>Testicles,
+    <a href="#Page_162">162</a>,
+    <a href="#Page_167">167</a></li>
+
+  <li>Tetragonolepis,
+    <a href="#Page_368">368</a></li>
+
+  <li>Tetragonopterus,
+    <a href="#Page_609">609</a></li>
+
+  <li>Tetragonurus,
+    <a href="#Page_501">501</a></li>
+
+  <li>Tetranematichthys,
+    <a href="#Page_572">572</a></li>
+
+  <li>Tetraroge,
+    <a href="#Page_417">417</a></li>
+
+  <li>Tetrodon,
+    <a href="#Page_688">688</a></li>
+
+  <li>Teuthididæ,
+    <a href="#Page_418">418</a></li>
+
+  <li>Teuthis,
+    <a href="#Page_419">419</a></li>
+
+  <li>Thalassophryne,
+    <a href="#Page_468">468</a></li>
+
+  <li>Thalassorhinus,
+    <a href="#Page_319">319</a></li>
+
+  <li>Thaleichthys,
+    <a href="#Page_647">647</a></li>
+
+  <li>Thaumas,
+    <a href="#Page_334">334</a></li>
+
+  <li>Thectodus,
+    <a href="#Page_330">330</a></li>
+
+  <li>Therapon,
+    <a href="#Page_385">385</a></li>
+
+  <li>Tholichthys,
+    <a href="#Page_172">172</a></li>
+
+  <li>Thoracic fins,
+    <a href="#Page_42">42</a></li>
+
+  <li>Thornback,
+    <a href="#Page_341">341</a></li>
+
+  <li>Thrissonotus,
+    <a href="#Page_370">370</a></li>
+
+  <li>Thrissopater,
+    <a href="#Page_656">656</a></li>
+
+  <li>Thrissops,
+    <a href="#Page_371">371</a></li>
+
+  <li>Thunberg,
+    <a href="#Page_13">13</a></li>
+
+  <li>Thymallus,
+    <a href="#Page_649">649</a></li>
+
+  <li>Thynnichthys,
+    <a href="#Page_595">595</a></li>
+
+  <li>Thynnus,
+    <a href="#Page_457">457</a></li>
+
+  <li>Thyrsites,
+    <a href="#Page_436">436</a></li>
+
+  <li>Thysanopsetta,
+    <a href="#Page_556">556</a></li>
+
+  <li>Tiger-shark,
+    <a href="#Page_327">327</a></li>
+
+  <li>Tilurus,
+    <a href="#Page_180">180</a></li>
+
+  <li>Tinca,
+    <a href="#Page_599">599</a></li>
+
+  <li>Tongue,
+    <a href="#Page_124">124</a></li>
+
+  <li>Tope,
+    <a href="#Page_318">318</a></li>
+
+  <li>Top-knot,
+    <a href="#Page_555">555</a></li>
+
+  <li>Torgoch,
+    <a href="#Page_645">645</a></li>
+
+  <li>Torpedinidæ,
+    <a href="#Page_338">338</a></li>
+
+  <li>Torpedo,
+    <a href="#Page_339">339</a></li>
+
+  <li>Torsk,
+    <a href="#Page_546">546</a></li>
+
+  <li>Touch, organ of,
+    <a href="#Page_120">120</a></li>
+
+  <li>Toxabramis,
+    <a href="#Page_604">604</a></li>
+
+  <li>Toxotes,
+    <a href="#Page_403">403</a></li>
+
+  <li>Trachelochismus,
+    <a href="#Page_513">513</a></li>
+
+  <li>Trachelyopterus,
+    <a href="#Page_572">572</a></li>
+
+  <li>Trachichthys,
+    <a href="#Page_422">422</a></li>
+
+  <li>Trachinidæ,
+    <a href="#Page_462">462</a></li>
+
+  <li>Trachinops,
+    <a href="#Page_418">418</a></li>
+
+  <li>Trachinopsis,
+    <a href="#Page_462">462</a></li>
+
+  <li>Trachinus,
+    <a href="#Page_463">463</a></li>
+
+  <li>Trachurus,
+    <a href="#Page_442">442</a></li>
+
+  <li>Trachynotus,
+    <a href="#Page_447">447</a></li>
+
+  <li>Trachypterus,
+    <a href="#Page_522">522</a></li>
+
+  <li>Transverse line,
+    <a href="#Page_50">50</a></li>
+
+  <li>Triacanthodes,
+    <a href="#Page_684">684</a></li>
+
+  <li>Triacanthus,
+    <a href="#Page_684">684</a></li>
+
+  <li>Triacis,
+    <a href="#Page_319">319</a></li>
+
+  <li>Triænodon,
+    <a href="#Page_319">319</a></li>
+
+  <li>Triænophorichthys,
+    <a href="#Page_487">487</a></li>
+
+  <li>Triassic fishes,
+    <a href="#Page_197">197</a></li>
+
+  <li>Trichiurichthys,
+    <a href="#Page_434">434</a></li>
+
+  <li>Trichiuridæ,
+    <a href="#Page_433">433</a></li>
+
+  <li>Trichiurus,
+    <a href="#Page_436">436</a></li>
+
+  <li>Trichocyclus,
+    <a href="#Page_689">689</a></li>
+
+  <li>Trichodiodon,
+    <a href="#Page_689">689</a></li>
+
+  <li>Trichodon,
+    <a href="#Page_466">466</a></li>
+
+  <li>Trichogaster,
+    <a href="#Page_518">518</a></li>
+
+  <li>Trichomycterus,
+    <a href="#Page_581">581</a></li>
+
+  <li>Trichonotus,
+    <a href="#Page_490">490</a></li>
+
+  <li>Trichopleura,
+    <a href="#Page_417">417</a></li>
+
+  <li>Trifurcated Hake,
+    <a href="#Page_545">545</a></li>
+
+  <li>Trigla,
+    <a href="#Page_478">478</a></li>
+
+  <li>Triglops,
+    <a href="#Page_480">480</a></li>
+
+  <li>Trigorhina,
+    <a href="#Page_338">338</a></li>
+
+  <li>Triodon,
+    <a href="#Page_687">687</a></li>
+
+  <li>Tripterodon,
+    <a href="#Page_406">406</a></li>
+
+  <li>Tripterygium,
+    <a href="#Page_495">495</a></li>
+
+  <li>Tristichopterus,
+    <a href="#Page_365">365</a></li>
+
+  <li>Tristychius,
+    <a href="#Page_314">314</a></li>
+
+  <li>Trochocopus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Tropical American region,
+    <a href="#Page_233">233</a></li>
+
+  <li>Trout,
+    <a href="#Page_644">644</a></li>
+
+  <li>Trubu,
+    <a href="#Page_660">660</a></li>
+
+  <li>Trumpeter,
+    <a href="#Page_412">412</a></li>
+
+  <li>Trumpet-fish,
+    <a href="#Page_509">509</a></li>
+
+  <li>Trunk,
+    <a href="#Page_39">39</a></li>
+
+  <li>Trygon,
+    <a href="#Page_343">343</a></li>
+
+  <li>Trygonidæ,
+    <a href="#Page_342">342</a></li>
+
+  <li>Trygonorhina,
+    <a href="#Page_338">338</a></li>
+
+  <li>Trypauchen,
+    <a href="#Page_489">489</a></li>
+
+  <li>Tunny,
+    <a href="#Page_458">458</a></li>
+
+  <li>Turbinal,
+    <a href="#Page_57">57</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Turbot,
+    <a href="#Page_555">555</a></li>
+
+  <li>Twaite Shad,
+    <a href="#Page_659">659</a></li>
+
+  <li>Tyellina,
+    <a href="#Page_326">326</a></li>
+
+  <li>Tylognathus,
+    <a href="#Page_596">596</a></li>
+
+  <li>Typhlichthys,
+    <a href="#Page_618">618</a></li>
+
+  <li>Typhlonus,
+    <a href="#Page_548">548</a></li>
+</ul>
+
+<ul>
+  <li>Uaru,
+    <a href="#Page_536">536</a></li>
+
+  <li>Ulna,
+    <a href="#Page_59">59</a></li>
+
+  <li>Umbra,
+    <a href="#Page_429">429</a>,
+    <a href="#Page_619">619</a></li>
+
+  <li>Umbrina,
+    <a href="#Page_428">428</a></li>
+
+  <li>Umbrine,
+    <a href="#Page_429">429</a></li>
+
+  <li>Undina,
+    <a href="#Page_365">365</a></li>
+
+  <li>Upeneichthys,
+    <a href="#Page_404">404</a></li>
+
+  <li>Upeneoides,
+    <a href="#Page_404">404</a></li>
+
+  <li>Upeneus,
+    <a href="#Page_404">404</a></li>
+
+  <li>Upokororo,
+    <a href="#Page_652">652</a></li>
+
+  <li>Uraleptus,
+    <a href="#Page_543">543</a></li>
+
+  <li>Uranoscopus,
+    <a href="#Page_462">462</a></li>
+
+  <li>Urinary organs,
+    <a href="#Page_155">155</a></li>
+
+  <li>Urocampus,
+    <a href="#Page_681">681</a></li>
+
+  <li>Urocentrus,
+    <a href="#Page_498">498</a></li>
+
+  <li>Uroconger,
+    <a href="#Page_674">674</a></li>
+
+  <li>Urogymnus,
+    <a href="#Page_343">343</a></li>
+
+  <li>Urohyal,
+    <a href="#Page_58">58</a>,
+    <a href="#Page_91">91</a></li>
+
+  <li>Urolophus,
+    <a href="#Page_343">343</a></li>
+
+  <li>Uronectes,
+    <a href="#Page_538">538</a></li>
+
+  <li>Uronemus,
+    <a href="#Page_360">360</a></li>
+
+  <li>Urosphen,
+    <a href="#Page_507">507</a></li>
+
+  <li>Urosthenes,
+    <a href="#Page_370">370</a></li>
+
+  <li>Useful fishes,
+    <a href="#Page_189">189</a></li>
+</ul>
+
+<ul>
+  <li>Vaillant,
+    <a href="#Page_31">31</a></li>
+
+  <li>Valenciennes,
+    <a href="#Page_18">18</a></li>
+
+  <li>Vandellia,
+    <a href="#Page_581">581</a></li>
+
+  <li>Velifer,
+    <a href="#Page_397">397</a></li>
+
+  <li>Vendace,
+    <a href="#Page_649">649</a></li>
+
+  <li>Ventral fins,
+    <a href="#Page_42">42</a></li>
+
+  <li>Vertebral column,
+    <a href="#Page_51">51</a></li>
+
+  <li>Vertical fins,
+    <a href="#Page_40">40</a></li>
+
+  <li>Villiform teeth,
+    <a href="#Page_126">126</a></li>
+
+  <li>Viviparous Blenny,
+    <a href="#Page_497">497</a></li>
+
+  <li>Vogt,
+    <a href="#Page_32">32</a></li>
+
+  <li>Vomer (bone),
+    <a href="#Page_56">56</a>,
+    <a href="#Page_89">89</a></li>
+
+  <li>Vomer (gen.),
+    <a href="#Page_441">441</a></li>
+
+  <li>Vulsus,
+    <a href="#Page_489">489</a></li>
+</ul>
+
+<ul>
+  <li>Wallago,
+    <a href="#Page_566">566</a></li>
+
+  <li>Wardichthys,
+    <a href="#Page_370">370</a></li>
+
+  <li>Weever,
+    <a href="#Page_464">464</a></li>
+
+  <li>Wels,
+    <a href="#Page_565">565</a></li>
+
+  <li>Whiff,
+    <a href="#Page_555">555</a></li>
+
+  <li>White-bait,
+    <a href="#Page_658">658</a></li>
+
+  <li>White-fish,
+    <a href="#Page_599">599</a>,
+    <a href="#Page_648">648</a></li>
+
+  <li>Whiting,
+    <a href="#Page_541">541</a></li>
+
+  <li>Whiting-pout,
+    <a href="#Page_541">541</a></li>
+
+  <li>Willughby,
+    <a href="#Page_8">8</a></li>
+
+  <li>Wrasses,
+    <a href="#Page_525">525</a></li>
+</ul>
+
+<ul>
+  <li>Xenocephalus,
+    <a href="#Page_553">553</a></li>
+
+  <li>Xenocharax,
+    <a href="#Page_612">612</a></li>
+
+  <li>Xenocypris,
+    <a href="#Page_598">598</a></li>
+
+  <li>Xenodermichthys,
+    <a href="#Page_664">664</a></li>
+
+  <li>Xenomystus,
+    <a href="#Page_576">576</a></li>
+
+  <li>Xenopterus,
+    <a href="#Page_688">688</a></li>
+
+  <li>Xiphias,
+    <a href="#Page_431">431</a></li>
+
+  <li>Xiphidion,
+    <a href="#Page_496">496</a></li>
+
+  <li>Xiphiidæ,
+    <a href="#Page_431">431</a></li>
+
+  <li>Xiphochilus,
+    <a href="#Page_530">530</a></li>
+
+  <li>Xiphopterus,
+    <a href="#Page_434">434</a></li>
+
+  <li>Xiphorhampus,
+    <a href="#Page_611">611</a></li>
+
+  <li>Xiphostoma,
+    <a href="#Page_611">611</a></li>
+</ul>
+
+<ul>
+  <li>Yarrell,
+    <a href="#Page_27">27</a></li>
+
+  <li>Yellow-tail,
+    <a href="#Page_444">444</a></li>
+</ul> 
+
+<ul>
+  <li>Zanchus,
+    <a href="#Page_449">449</a></li>
+
+  <li>Zaniolepis,
+    <a href="#Page_491">491</a></li>
+
+  <li>Zärthe,
+    <a href="#Page_603">603</a></li>
+
+  <li>Zebra-Shark,
+    <a href="#Page_327">327</a></li>
+
+  <li>Zeus,
+    <a href="#Page_451">451</a></li>
+
+  <li>Zoarces,
+    <a href="#Page_497">497</a></li>
+
+  <li>Zope,
+    <a href="#Page_603">603</a></li>
+
+  <li>Zuzuki,
+    <a href="#Page_378">378</a></li>
+
+  <li>Zygaena,
+    <a href="#Page_318">318</a></li>
+
+  <li>Zygapophyses,
+    <a href="#Page_52">52</a></li>
+
+  <li>Zygobatis,
+    <a href="#Page_346">346</a></li>
+</ul>
+
+<p class="center sm p2">THE END.</p>
+
+
+<p class="center xs p2"><i>Printed by</i> <span class="smcap">R. &amp; R. Clark</span>, <i>Edinburgh</i>.</p>
+
+
+<div class="footnotes"><h2>FOOTNOTES:</h2>
+
+<div class="footnote">
+
+<p><a id="Footnote_1" href="#FNanchor_1" class="label">[1]</a> From ιχθυς, fish, and λογος, doctrine or treatise.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_2" href="#FNanchor_2" class="label">[2]</a> Down to this period the history of Ichthyology is fully
+treated in the first volume of Cuvier and Valenciennes “Hist. nat. d.
+Poiss.”</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_3" href="#FNanchor_3" class="label">[3]</a> Description of Ceratodus. “Phil. Trans.,” 1871, ii.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_4" href="#FNanchor_4" class="label">[4]</a> In the formula generally preceding the description of a
+fish, “L. lat. 40,” would express that the scales between the head and
+caudal fin are arranged in 40 transverse series; and probably, that
+the lateral line is composed of the same number of scales. “L. transv.
+8/5” would express that there are eight longitudinal series of scales
+between the median line of the back and the lateral line, and five
+between the lateral line and the middle of the abdomen.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_5" href="#FNanchor_5" class="label">[5]</a> Pterotic of Parker.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_6" href="#FNanchor_6" class="label">[6]</a> <i>C. Hasse</i> has studied the modifications of the
+texture of the vertebræ and the structure of the Chondropterygian
+skeleton generally, and shown that they correspond in the main to the
+natural groups of the system, and, consequently, that they offer a
+valuable guide in the determination of fossil remains.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_7" href="#FNanchor_7" class="label">[7]</a> The Ganoids formed at former epochs the largest and most
+important order of fishes, many of the fossil forms being known from
+very imperfect remains only. It is quite possible that not a few of
+the latter, in which nothing whatever of the (probably very soft)
+endoskeleton has been preserved, should have to be assigned to some
+other order lower in the scale of organisation than the Ganoids (for
+instance, the <i>Cephalaspidæ</i>).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_8" href="#FNanchor_8" class="label">[8]</a> As first proposed by Huxley.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_9" href="#FNanchor_9" class="label">[9]</a> Stannius (pp. 60, 65) doubts the pure origin of these two
+bones from membranous tissue, and is inclined to consider them as “the
+extreme end of the abortive axial system.”</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_10" href="#FNanchor_10" class="label">[10]</a> Parker’s nomenclature is adopted here.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_11" href="#FNanchor_11" class="label">[11]</a> According to <i>Langerhans</i> “Untersuchungen über
+Petromyzon planeri” (Freiburg, 1873) an optic chiasma exists in that
+species.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_12" href="#FNanchor_12" class="label">[12]</a> This nerve is not shown in the figure of the brain of the
+Perch (Fig. 41), as reproduced above from Cuvier.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_13" href="#FNanchor_13" class="label">[13]</a> Müller considers a nerve rising jointly with the Vagus in
+Petromyzon to be this nerve (Fig. 45, <i>hy</i>).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_14" href="#FNanchor_14" class="label">[14]</a> On the development and structure of the dentition
+of <i>Scarina</i>, see <i>Boas</i>, “Die Zähne der Scaroiden,” in
+Zeitschr. f. Wiss. Zoolog. xxxii. (1878).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_15" href="#FNanchor_15" class="label">[15]</a> This applies to individuals only growing up under normal
+conditions. Dr. H. A. Meyer has made observations on young Herrings.
+Individuals living in the sea had attained at the end of the third
+month a length of 45 to 50 millimetres, whilst those reared from
+artificially-impregnated ova were only from 30 to 35 millimetres long.
+When the latter had been supplied with more abundant food, they grew
+proportionally more rapidly in the following months, so that at the end
+of the fifth month they had reached the same length as their brethren
+in the sea, viz. a length of 65 to 70 millimetres.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_16" href="#FNanchor_16" class="label">[16]</a> Ray Lankester considers it to be a portion of the
+long denticulated cornua of a genus <i>Eukeraspis</i> allied to
+<i>Cephalaspis</i>.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_17" href="#FNanchor_17" class="label">[17]</a> Ekström, Fische in den Scheeren von Mörkö.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_18" href="#FNanchor_18" class="label">[18]</a> Will probably be found.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_19" href="#FNanchor_19" class="label">[19]</a> We distinguish these sub-regions, because their
+distinction is justified by other classes of animals; as regards
+freshwater fishes their distinctness is even less than that between
+Europe and Northern Asia.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_20" href="#FNanchor_20" class="label">[20]</a> Martens (Preuss. Exped. Ostas. Zool. i. p. 356), has
+already drawn attention that a Barbel, said to have been obtained by
+Ida Pfeiffer in Amboyna (Günth. Fish. vii. p. 123), cannot have come
+from that locality.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_21" href="#FNanchor_21" class="label">[21]</a> In the following and succeeding lists, those forms which
+are peculiar to and exclusively characteristic of, the region, are
+printed in italics; the other regions, in which the non-peculiar forms
+occur, are mentioned within brackets [].</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_22" href="#FNanchor_22" class="label">[22]</a> Lates calcarifer in India as well as Australia.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_23" href="#FNanchor_23" class="label">[23]</a> One species (<i>Arius thalassinus</i>) found in Indian
+and African rivers.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_24" href="#FNanchor_24" class="label">[24]</a> This species extends from India into East Africa.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_25" href="#FNanchor_25" class="label">[25]</a> We have left out from these considerations the Ariina and
+Cyprinodonts, which can pass with impunity through salt water, and are
+spread over much larger areas.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_26" href="#FNanchor_26" class="label">[26]</a> Cope has discovered in a tertiary freshwater-deposit at
+Idaho an extinct genus of this group, <i>Diastichus</i>. He considers
+this interesting fact to be strongly suggestive of continuity of
+territory of Asia and North America.—“Proc. Am. Phil. Soc. 1873,” p.
+55.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_27" href="#FNanchor_27" class="label">[27]</a> Leidy describes a Siluroid (<i>Pimelodus</i>) from
+tertiary deposits of Wyoming Territory. “Contrib. to the Extinct Vert.
+Fauna of the Western Territ. 1873,” p. 193.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_28" href="#FNanchor_28" class="label">[28]</a> The genera peculiar to the Equatorial zone are printed in
+italics.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_29" href="#FNanchor_29" class="label">[29]</a> Number of species uncertain.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_30" href="#FNanchor_30" class="label">[30]</a> See p. 151, Fig. 67.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_31" href="#FNanchor_31" class="label">[31]</a> See p. 128, Fig. 55.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_32" href="#FNanchor_32" class="label">[32]</a> See p. 104.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_33" href="#FNanchor_33" class="label">[33]</a> See p. 167, Figs. 79, 81.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_34" href="#FNanchor_34" class="label">[34]</a> See p. 136, Fig. 58.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_35" href="#FNanchor_35" class="label">[35]</a> See p. 167, Fig. 78.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_36" href="#FNanchor_36" class="label">[36]</a> The cartilaginous jaws of Sharks shrink at least a third
+in drying, and, therefore, cannot be kept at full stretch without
+tearing.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_37" href="#FNanchor_37" class="label">[37]</a> This exception is a Ray obtained during the “Challenger”
+expedition, and said to have been dredged in 565 fathoms.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_38" href="#FNanchor_38" class="label">[38]</a> See pp. 73 and 74, Figs. 35 and 36.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_39" href="#FNanchor_39" class="label">[39]</a> For other illustrations see p. 73, Fig. 35 (palatal view
+of head); p. 74, Fig. 36 (pectoral skeleton); p. 141, Fig. 60 (gills);
+p. 148, Fig. 65 (lung); p. 151, Fig. 67 (heart); p. 134, Fig. 57
+(intestine); p. 165, Fig. 77 (ovary).</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_40" href="#FNanchor_40" class="label">[40]</a> See p. 97, Fig. 41; and p. 152, Fig. 68.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_41" href="#FNanchor_41" class="label">[41]</a> The Acanthopterygians do not form a perfectly natural
+group, some heterogeneous elements being mixed up with it. Neither are
+the characters, by which it is circumscribed, absolutely distinctive.
+In some forms (certain Blennioids) the structure of the fins is
+almost the same as in Anacanths; there are some Acanthopterygians, as
+<i>Gerres</i>, <i>Pogonias</i>, which possess coalesced pharyngeals;
+and, finally, the presence or absence of a pneumatic duct loses much of
+its value as a taxonomic character when we consider that probably in
+all fishes a communication between pharynx and air-bladder exists at an
+early stage of development.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_42" href="#FNanchor_42" class="label">[42]</a> In this instance, one may entertain reasonable doubts as
+to the usefulness of the Pilot to the Shark.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_43" href="#FNanchor_43" class="label">[43]</a> Mackerel, like other marine fishes, birds, and mammals
+of prey, follow the shoals of young and adult Clupeoids in their
+periodical migrations; on the British coasts it is principally the fry
+of the Pilchard and Sprat which wanders from the open sea towards the
+coast, and guides the movements of the Mackerel.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_44" href="#FNanchor_44" class="label">[44]</a> The systematic affinities of these extinct genera
+are very obscure. Cope places them, with others (for instance
+<i>Protosphyræna</i>, which has a sword-like prolongation of the
+ethmoid), in a distinct family, <i>Saurodontidæ</i>: see “Vertebrata of
+the Cretaceous Formations of the West,” 1875.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_45" href="#FNanchor_45" class="label">[45]</a> For specific characters and detailed descriptions we
+refer to Günther, “Catal. of Fishes,” vol. vi.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_46" href="#FNanchor_46" class="label">[46]</a> The names “Bull-trout” and “Peal” are not attributable
+to definite species. We have examined specimens of <i>S. salar</i>,
+<i>S. trutta</i>, and <i>S. cambricus</i> and <i>S. fario</i>, to which
+the name “Bull-trout” had been given; and that of “Peal” is given
+indiscriminately to Salmon-grilse and to <i>S. cambricus</i>.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_47" href="#FNanchor_47" class="label">[47]</a> Fig. 317 is taken from a specimen in which the horny
+covers of the dentition were lost, hence it does not represent
+accurately the shape of the teeth.</p>
+
+</div>
+
+<div class="footnote">
+
+<p><a id="Footnote_48" href="#FNanchor_48" class="label">[48]</a> This name is two years older than <i>Amphioxus</i>.</p>
+
+</div>
+</div>
+
+
+<p class="transnote">Transcriber’s Notes:<br>
+<br>
+<br>1. Obvious printers’, punctuation and spelling errors have been
+corrected silently.<br>
+<br>
+<br>2. Where hyphenation is in doubt, it has been retained as in the
+original.<br>
+<br>
+3. Some hyphenated and non-hyphenated versions of the same words have
+been retained as in the original.</p>
+
+
+<div style='text-align:center'>*** END OF THE PROJECT GUTENBERG EBOOK AN INTRODUCTION TO THE STUDY OF FISHES ***</div>
+</body>
+</html>
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author	nfenwick <nfenwick@pglaf.org>	2025-01-17 13:23:57 -0800
committer	nfenwick <nfenwick@pglaf.org>	2025-01-17 13:23:57 -0800
commit	566758a49b2a78fdc30bda14439c1cfccc88f3eb (patch)
tree	399e96cffc6d05590c575d09d80f576a8af9fc15