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diff --git a/40005-0.txt b/40005-0.txt new file mode 100644 index 0000000..00cbca8 --- /dev/null +++ b/40005-0.txt @@ -0,0 +1,11525 @@ +*** START OF THE PROJECT GUTENBERG EBOOK 40005 *** + +Transcriber's Notes + + Mathematical Notation + + 1) _{#} for subscripted number or character and + ^{#} for superscripted number or character + Example: Carbonate Ion = CO_{3}^{--} + + 2) Whole and fractional number: 7-2/3 + + Text Emphasis + + Italic words displayed as _Text_ and bold as =Text=. + + + + +UNIVERSITY OF KANSAS PUBLICATIONS + +MUSEUM OF NATURAL HISTORY + + +Volume 13, No. 10, pp. 429-611, pls. 31-54, 24 figs. + +February 16, 1962 + + + + +North American Recent Soft-shelled Turtles + +(Family Trionychidae) + + +BY + + +ROBERT G. WEBB + + + + +UNIVERSITY OF KANSAS + +LAWRENCE + +1962 + + +UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY + +Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson + + +Volume 13, No. 10, pp. 429-611, pls. 31-54, 24 figs. + +Published February 16, 1962 + + +UNIVERSITY OF KANSAS + +Lawrence, Kansas + + +PRINTED IN + +THE STATE PRINTING PLANT + +TOPEKA, KANSAS + +1962 + +[Illustration (Union Label)] + +28-7818 + + + + + +North American Recent Soft-shelled Turtles + +(Family Trionychidae) + + +BY + + +ROBERT G. WEBB + + + + +CONTENTS + + + PAGE + + CONTENTS 431 + + INTRODUCTION 433 + Collecting Methods 434 + Materials and Procedure 437 + Acknowledgments 439 + + TAXONOMY 439 + Family Trionychidae Bell, 1828 439 + Genus _Trionyx_ Geoffroy, 1809 443 + Variation 445 + Secondary Sexual Variation 446 + Ontogenetic Variation 449 + Geographic Variation 453 + Character Analysis 460 + Composition of the Genus _Trionyx_ in North America 476 + Artificial Key to North American Species and Subspecies + of the Genus _Trionyx_ 476 + Systematic Account of Species and Subspecies 479 + _Trionyx ferox_ 479 + _Trionyx spinifer_ 486 + _Trionyx spinifer spinifer_ 489 + _Trionyx spinifer hartwegi_ 497 + _Trionyx spinifer asper_ 502 + _Trionyx spinifer emoryi_ 510 + _Trionyx spinifer guadalupensis_ 517 + _Trionyx spinifer pallidus_ 522 + _Trionyx ater_ 528 + _Trionyx muticus_ 531 + _Trionyx muticus muticus_ 534 + _Trionyx muticus calvatus_ 539 + + NATURAL HISTORY 541 + Habitat 541 + Daily and Seasonal Activity 547 + Diurnal Habits 547 + Behavior Adaptations 549 + Movement 552 + Nocturnal Habits 553 + Seasonal Occurrence 553 + Food Habits 555 + Reproduction 558 + Size of Males at Sexual Maturity 558 + Size of Females at Sexual Maturity 560 + Sexual Activity 563 + Deposition of Eggs 565 + Reproductive Potential 568 + Eggs 572 + Incubation and Hatching 573 + Age and Growth 574 + Mortality 576 + Parasites 576 + Economic Importance 577 + + EVOLUTIONARY HISTORY 578 + Distribution 578 + Relationships 579 + Fossils 582 + Phylogeny 585 + The Importance of the Study of Turtle Populations in + Relation to the History of River Systems 588 + + SUMMARY 590 + + LITERATURE CITED 594 + + + + +INTRODUCTION + + +Is it true that the greater the degree of resemblance between two +populations the shorter the time the two have been spatially isolated? +Are aquatic environments more stable than terrestrial environments? +These questions occurred to me while I was collecting turtles from river +systems of the Gulf Coast. As a general rule, each kind of turtle seemed +to occur throughout one continuous river system or large tributary, and +with no barriers to dispersal therein and with the lapse of enough time +for a population to reach its limits of dispersal, the question arose, +"Where do subspecies and zones of intergradation occur?" It seemed +logical to think that each isolated and continuous aquatic environment +would not contain more than one subspecies of the same species. In +terrestrial environments subspecies and transitions between them were +recognizable. Terrestrial habitats were continuous for longer distances +than the isolated, aquatic habitats. But, different species of turtles +prefer different kinds of aquatic habitats. Also, barriers occur in +large drainage systems, such as the Mississippi, where, in general, +the western tributaries are sluggish, turbid and shallow, and the +eastern tributaries are fast-flowing, clear and deep. But in young, +relatively small, river systems that do not traverse radically different +physiographic regions, and that show no gross ecological differences, +habitats or microhabitats that do exist probably are only partial +barriers and seem not to prevent the dispersal of most kinds of aquatic +turtles. Consequently, it seemed that study of the degree of difference +between closely related populations of turtles that occurred in one +drainage system, or in adjacent drainage systems would indicate the +length of time, respectively, that the drainage system had been +continuous or the length of time that two or more systems had been +isolated from one another. + +Rivers or series of river systems having endemic kinds of turtles or +having the most kinds of turtles that are different from those in +adjacent rivers may be the oldest geologically, or may have been +isolated the longest. Knowledge of the kinds of turtles and their +relationships and distribution could indicate chronological changes in +aquatic habitats. Of course, modifying factors such as differences +between populations of turtles in rates of evolutionary change, degrees +of vagility, rates of dispersal, and overland migrations need to be +taken into account. + +My accumulation of data on soft-shelled turtles was begun in the early +nineteen-fifties. Although American softshells have been discussed in a +revisionary manner by Agassiz (1857), Siebenrock (1924), Stejneger +(1944) and Neill (1951), the relationships of all the component +populations have not hitherto been appreciated. The present account +attempts to combine in one publication what is known concerning the +taxonomy, geographic distribution, life history, and relationships of +the Recent American species and subspecies of the genus _Trionyx_. + + +Collecting Methods + +Nocturnal collecting, by hand, from a boat that was nosed among brush +piles along the shore line of rivers (Chaney and Smith, 1950:323) in the +early 1950's on rivers of the Gulf Coast drainage east of Texas yielded +many turtles of the genus _Graptemys_ but few softshells. Chaney and +Smith (_loc. cit._) reported only one softshell among 336 turtles taken +in 21 collecting hours on July 5, 6 and 7 on the Sabine River; Cagle and +Chaney (1950:385), however, recorded 11.6 per cent softshells of 208 +turtles (collecting time not stated) taken on the Caddo Lake Spillway in +Louisiana. Using hoop-nets is probably the most efficient method for +collecting softshells considering the time and effort involved, and is +the chief method I have used. Lagler (1943a:24) mentioned the use of +watermelon rind as an effective bait. Kenneth Shain (field notes) +trapped _T. spinifer emoryi_ in hoop-nets baited with bread. I have used +chopped fresh fish with most success; canned sardines have also been +satisfactory. These baits seem to be more successful for trapping +_spinifer_ than they are for _muticus_. Hoop-nets were used to trap +turtles in Lake Texoma, Oklahoma, from June 14 to July 2, 1954. The +number of traps (usually four, rarely five) and trapping success varied +with location. Of 156 turtles, 19 (12%) were _T. spinifer_ and one was +_T. muticus_. + +Trotlines and set lines frequently catch softshells; sport fishermen +often complain of catching these turtles on hook and line. Live worms, +soft-bodied insects, small crawfish, minnows, small pieces of fish and +other kinds of meat are adequate bait. Capture depends on the skill of +attachment of the bait and the size of hook used. In my experience, +softshells (mostly _spinifer_) were taken on trotlines that were set in +lakes or the slower-moving parts of rivers a few inches below the +surface. I have records of only two _muticus_ taken on trotlines. +Goin (1948:304) stated that commercial fishermen catch softshells on +trotlines set for catfish on the bottom of river beds. Evermann and +Clark (1920:595) found softshells to be caught more often than any +other kind of turtle in traps, on set lines, and by anglers in Lake +Maxinkuckee, Indiana. Some residents of the South tell of so placing +baits that turtles are lured to tread water against an object set with +recurved hooks upon which the webbing of the forelimbs are impaled. + +Individuals of _muticus_ and _spinifer_ frequently bury themselves in +sand in shallow water and can be collected by hand by noting swirls or +disturbances on the bottom caused by a turtle withdrawing its head +(Conant, 1951:156, 159). Professional turtle collectors take them by +"noodeling" (Conant, _op. cit._:160); Lagler (1943a:22) elaborated on +the method of "noodling." P. W. Smith (1947:39) remarked that 20 or more +softshells were taken "within a few hours by probing sand bars at the +water edge" near Charleston, Illinois. From a distance I observed an +individual of _T. s. asper_ bury itself in shallow water on the Escambia +River, Florida. Small individuals of _muticus_ have been taken by hand +along the shore of Lake Texoma. Along the Flint River near Bainbridge, +Georgia, two hatchlings that were buried in sand in shallow water +emerged at my approach and scurried a few inches, then buried themselves +again. Larger turtles seem to be more wary. One that was disturbed, +emerged from the sand and swam toward deep water. + +In clear water, water-goggling may be effective in securing softshells. +Marchand (_in_ Carr, 1952:417-18) mentioned that softshells (_ferox_) +can be found buried in deep water with only the heads visible; the +turtles are not easily frightened under water and may be captured by +grasping their necks. A similar technique described by Allen and Neill +(1950:3) resulted in the capture of trionychid turtles. In clear water +of the White River, Arkansas, I collected a few softshells by hand as +they lay on the bottom. + +In shallow-water areas of large rivers, lakes and tributaries, seining +often procures softshells. Methods used in fisheries investigations such +as the application of rotenone and electric shockers, and even +dynamiting, sometimes yield soft-shelled turtles. Carr (1952:419) wrote +that numbers of _ferox_ were incapacitated by rotenone in Florida lakes, +although no other species of turtle was affected. I captured a snapping +turtle (_Chelydra serpentina_) that was immobilized by the current from +an electric shocker in a small, alga-choked tributary of Cache Creek, +Comanche County, Oklahoma; presumably turtles must come in close contact +with the electrodes to be affected (see discussion by Gunning and Lewis, +1957:52). + +The effectiveness of gill nets in trapping turtles is indicated by +information kindly supplied by Mr. Alfred Houser on gill-net operations +from July through December, 1952, under the direction of Mr. "Bud" +Oldham, a commercial fisherman. The 4-inch mesh nets were in Lake Texoma +at the mouth of Briar Creek, two miles south of Powell, Marshall County, +Oklahoma, in 25 to 30 feet of water. Eighty to 90 per cent of the +turtles secured were softshells; more were taken near shoreline than +away from shore even though the depth was about the same. An average of +only one turtle every four days was taken in July and August when the +turtles presumably are most active (Table 1). One gill-net day is +equivalent to one gill net, 200 yards long, operated for 24 hours. + + TABLE 1. The Abundance of Turtles as Revealed by Gill-net + Operations in Lake Texoma, 1952. + + ===========+==========+===========+=============== + | Gill-net | Number of | Gill-net days + MONTH | days | turtles | per turtle + -----------+----------+-----------+--------------- + July | 835 | 213 | 3.9 + August | 816 | 199 | 4.6 + September | 743 | 42 | 17.7 + October | 1661 | 82 | 20.3 + November | 1322 | 48 | 27.5 + December | 864 | 5 | 172.8 + -----------+----------+-----------+--------------- + +Dr. Virgil Dowell, while making fishery studies two miles east of +Willis, Marshall County, Oklahoma, caught, on the average, 1.5 turtles +per day. Of 75 turtles collected from July 1 through October 18, 1953, +66 were _Trionyx_ (_spinifer_ and _muticus_), five were _Graptemys_ and +four were _Pseudemys scripta_. No more than two gill nets were used +simultaneously. The nets were moved from time to time and varied in +dimensions, but those used most of the time were 200 feet long and eight +feet deep with a 3-inch mesh. + +The few captures by Houser probably resulted from long-continued +trapping in one place; the gill nets were not moved in the entire +six-month period or for some time previously. Breckenridge (1955:6) +commented on the sedentary nature of _spinifer_ (in Minnesota) and +quoted a professional turtle trapper as stating that "after a section of +a river has been trapped heavily for softshells, little success can be +expected in that area for as much as three or four years thereafter." +Both Houser's and Dowell's data indicate a higher percentage of +soft-shelled turtles collected than any other species. The number +caught probably depends, at least partly, on the food habits of the +species and is influenced by the enmeshed fish, which, serving as a food +source, attract the turtles. + + +Materials and Procedures + +In the course of this study I examined 1849 soft-shelled turtles, +including some incomplete alcoholic or dried specimens, such as those +represented only by skulls or by other osteological material. Material +was examined from each of the collections named below (except KKA), and +these are mentioned in the text by the following abbreviations: + + AMNH American Museum of Natural History + ANSP Academy of Natural Sciences, Philadelphia + BCB Bryce C. Brown, private collection, Baylor University + CM Carnegie Museum + CNHM Chicago Natural History Museum + INHS Illinois Natural History Survey, University of Illinois + KKA Kraig K. Adler, private collection, data in letter dated January 8, 1960 + KU Museum of Natural History, The University of Kansas + LSU Louisiana State University + MCZ Museum of Comparative Zoology, Harvard College + MSU The Museum, Michigan State University + NHB Naturhistorisches Museum Basel, Switzerland + OU University of Oklahoma Museum, Division of Zoology + SM Strecker Museum, Baylor University + TCWC Texas Cooperative Wildlife Collection, Texas Agricultural and Mechanical College + TNHC Texas Natural History Collection, The University of Texas + TTC Texas Technological College + TU Tulane University + UA University of Alabama + UI Museum of Natural History, The University of Illinois + UMMZ Museum of Zoology, The University of Michigan + USNM United States National Museum + WEB William E. Brode, private collection, Mississippi Southern College + WTN Wilfred T. Neill, private collection + +External measurements (listed under the section, "Variation") were +taken by the writer by means of a Vernier caliper or a steel tape. +Measurements of the skulls are in millimeters and tenths as taken by +the writer with dial calipers. Partial wrinkling of the carapace at +the edges of some specimens causes some error in measurements; +consequently, length of plastron is used as the measurement of +reference. + +Scattergrams based on external measurements were constructed. Some +demonstrate considerable ontogenetic variation. An inspection of the +scattergrams indicated regressions essentially linear in nature, but +sometimes occasioned an arbitrary separation of samples into size +groups to show ontogenetic variation; no secondary sexual differences +could be discerned. Several ratios were developed from the +measurements. The data correspond to the regression model 1A in +"Statistical Methods" (Snedecor, 1956, sec. 6.13); consequently, the +sample ratios indicate the slope of regression and are useful in +comparisons. Sample-means and their estimated standard errors are +compared graphically to show general trends in proportional +characters. Comparisons of means and standard errors indicate +statistical significance between populations if the sample-means plus +or minus twice their standard errors do not overlap, but this method +of comparison is valid only when comparing two samples (Pimentel, +1959:100). + +In the section on "Variation," general features applicable to all +kinds of soft-shelled turtles are discussed under the following +headings: secondary sexual, ontogenetic, and geographic; individual +variation is mentioned in accounts of species and subspecies. In the +section "Character Analysis" external and osteological characters +having taxonomic significance are discussed. + +Vernacular names follow, as closely as possible, those recommended by +the Committee on Herpetological Common Names (1956). The synonymy of +each monotypic species or subspecies begins with the name as given in +the original description. The second entry is the name-combination +herein applied to the taxon. Other entries are first usages, in +chronological order, of other names (synonyms) that have been applied +to the taxon in question. Next, the type is briefly discussed followed +by the "Range" defined in general geographic terms, and, when +appropriate, in terms of river drainage systems. "Diagnosis" includes +a combination of characters that facilitates quick identification. In +polytypic species, the diagnosis of a subspecies is designed only to +distinguish it from other subspecies of that species. The comments +included under the subsection entitled "Description" pertain to +individuals from an area where the taxon is most clearly +differentiated. Because osteological characters are significant only +at the specific level, they appear under the accounts of each species +(excluding _ater_). Proportional characters as given in the +"Diagnosis" are only in general terms; more specific data are set +forth in the subsection, "Description" or in the various text figures, +mostly in the section on "Variation," page 445. Proportions pertaining +to the species _muticus_ were derived only from the nominal +subspecies, and appear under the account of the species. A subsection +"Variation" under the accounts of some subspecies includes information +concerning principally individual variation and coloration; because +color is not considered to be of major taxonomic importance, color +terms are used without reference to any standard color guide. The +subsection "Remarks" follows the section on "Comparisons," and may +include comments on nomenclature, intergradation and other information +related to the distribution or taxonomy of the subspecies. + +The probable geographic range of each species and subspecies is shown +on one of the maps. Locality records of specimens that I have examined +are shown by solid circles. Additional records of occurrence +(published records or specimens otherwise not seen) are shown by +hollow circles. Localities only a short distance apart share the same +circle. + +Under the subsection "Specimens examined," a number in parentheses +following a museum number indicates the number of specimens referable +to that museum number. All localities of specimens examined are +indicated on one of the maps. The list of specimens is arranged +alphabetically by states (Canadian provinces precede states of the +United States under the account of _T. spinifer spinifer_, and Mexican +states follow those of the United States under _T. s. emoryi_), +alphabetically by counties, and within a county alphabetically by +abbreviations of museums; then, museum catalogue numbers are arranged +consecutively. Records in the literature are not included if they +refer to the same locality from which at least one specimen has been +examined, or refer to a less restricted locality that includes the +area from which at least one specimen has been examined. Localities +within a county are arranged alphabetically by author; the appropriate +reference may follow several localities. + +All generic, specific and subspecific names (but not all the different +kinds of name-combinations) that have been applied to American +soft-shelled turtles are listed in a subsection entitled "Synonymy" +under the heading "Genus Trionyx Geoffroy, 1809." + + +Acknowledgments + +Completion of this study has been made possible only by the +co-operation of those persons in charge of the collections listed +above and I am grateful to them for the privilege of examining +specimens. Also I wish to thank Dr. E. Raymond Hall for the facilities +afforded by the Museum of Natural History at the University of Kansas, +as well as for editorial assistance in the preparation of the +manuscript, and especially Dr. Henry S. Fitch under whose guidance +this research was carried out. + +In addition to various staff members, graduate students, and +individuals whose help is acknowledged at appropriate places in the +text, Dr. Rollin H. Baker, Dr. Fred R. Cagle, Mr. J. Keever Greer, Dr. +A. Byron Leonard, Dr. Carl D. Riggs, and Dr. Edward H. Taylor deserve +especial mention for aid extended in the course of this study. I am +indebted to Mr. J. C. Battersby, British Museum (Natural History), +London, for information concerning the type of _Trionyx ferox_, to Dr. +Jean Guibé, Museum d'Histoire Naturelle, Paris, for information +concerning the types of _Trionyx muticus_, _T. spinifer_ and _T. +carinatus_, and photographs of the types of _T. muticus_, _T. +spinifer_ and _T. ocellatus_, and to Dr. Lothar Forcart of the +Naturhistorisches Museum, Basel, Switzerland, for information +pertaining to a published record of _T. muticus_. + +The maps and figures are the work of Miss Lucy Jean Remple and Mrs. +Lorna Cordonnier, University of Kansas. Dr. John M. Legler, University +of Utah, prepared most of the photographs on plates 1-20; photographs +as mentioned in the preceding paragraph were received from Dr. Guibé, +one was provided through the co-operation of Roger Conant and Isabelle +Hunt Conant, another was furnished by Mr. J. Keever Greer, and the +others were taken by me. Field work was financed in part by funds +provided by the Sigma Xi-RESA Research Fund. + + + + +TAXONOMY + + +Family Trionychidae Bell, 1828 + +Recent soft-shelled turtles comprise a well-defined assemblage of the +family Trionychidae. Although the scope of this study does not involve +an assay of the relationships of the soft-shelled turtles of the Old +World, a brief résumé that includes some of the salient characteristics +of the family is included. + +_Diagnosis._--Articulation between last cervical and first dorsal +vertebrae by zygopophyses only; preplastra separated from hyoplastra +by /\-shaped epiplastron, entoplastron absent (Williams and McDowell, +1952:263-75); marginal bones absent or forming an incomplete series, +not connected with ribs that extend beyond pleural plates; claws on +only three inner digits; fourth digit having four or more phalanges; +plastron united to carapace by ligamentous tissue (Smith, 1931:147). + +_General characters._--Size large, "... some attaining probably 5 feet +in length of carapace" (Boulenger, 1890:10); body depressed; carapace +and plastron lacking horny epidermal shields, covered instead with +soft skin; snout ending in fleshy, tubate proboscis; jaws concealed by +fleshy lips; tail short; digits well-webbed; cervical vertebrae +opisthocoelous (eighth having double articulation in front); neck +elongate, cervical region equaling or exceeding length of dorsal +vertebral column; head and neck completely retractile, bending by +means of sigmoid curve in vertical plane; ear hidden; skull elongate, +having three posterior projections (median one produced by +supraoccipital and two lateral projections formed chiefly by +squamosals); temporal region emarginate posteriorly, forming wide +shallow fossa; premaxillae fused; an intermaxillary foramen; +pterygoids separated by basisphenoid that contacts palatines; vomer, +if present, not separating palatines; pelvis not fused to carapace and +plastron; plastron reduced, a median vacuity usually present; plastral +bones developing sculpturing with increase in size, forming four to +seven so-called plastral callosities; carapace with or without +prenuchal bone; nuchal overlapping or overlapped by first pleural; +neurals in continuous series or interrupted by pleurals; bony plates +of carapace sculptured; mandible having well-developed coronoid bone; +cutaneous femoral valves that conceal hind limbs present or absent; +two or three pairs of scent glands; cloacal bursae absent (Smith and +James, 1958:89); forelimbs having antebrachial scalation; body of +hyoid apparatus formed of two or three pairs of bones; penis broad, +expanded and pentifid, sulcus spermaticus quadrifid having branches in +each of four lateral projections (Hoffman, 1890:298, pl. 47, fig. 2); +aquatic, principally in fresh water; mainly carnivorous; flesh of many +species eaten. (See Boulenger, 1889:237-41; Loveridge and Williams, +1957:412; Romer, 1956:513; Smith, _op. cit._:147-54). + +_Recent distribution_ (Figure 1).--North America, from extreme +southeastern Canada and eastern United States west to Rocky Mountains +and south to northern México; introduced in southwestern United States +(Conant, 1958:69-73). Africa, from Egypt and Senegal south to Angola +and Zambesi River drainage (Loveridge and Williams, _op. +cit._:412-68); occurrence of _Trionyx triunguis_ in Syria (Boulenger, +_op. cit._:255) and coastal streams of Palestine (Schmidt and Inger, +1957:36) considered accidental by Flower (1933:753-54). Southwestern +Asia (Tigris and Euphrates River drainage) in eastern Turkey, Syria, +Iraq and northeastern Israel (Mertens and Wermuth, 1955:388). +Southeastern Asia, from Pakistan and India (Indus River drainage) and +Manchuria and adjacent Siberia (Amur River drainage) to Ceylon, Japan, +Formosa, Hainan, Luzon, Sumatra, Java, Borneo, Timor and southeastern +New Guinea (De Rooij, 1915:325-32; Okada, 1938:108; Pope, 1935:60-64; +Smith, 1931:158-79; Stejneger, 1907:514-532; Taylor, 1920:141). + +_Trionyx cartilagineus_ is questionably recorded from the Moluccas (De +Rooij, _op. cit._:330). _T. sinensis_ has been introduced on Kauai +Island, Hawaiian Islands (Brock, 1947:142; Oliver and Shaw, 1953:83), +one of the Bonin Islands (Okada, 1930:187-94), and probably Timor (De +Rooij, _op. cit._:331). All insular records east of Borneo and Java +are probably the result of introductions, except perhaps those of +_Pelochelys_ on Luzon and New Guinea (Darlington, 1957:210). + + [Illustration: FIG. 1. Geographic distribution of the family + Trionychidae.] + +_Recent genera._--According to Mertens and Wermuth (1955:387-95), there +are 21 species belonging to six genera as follows: + + _Chitra_ Gray, 1844 (1) + _Cyclanorbis_ Gray, 1854 (2) + _Cycloderma_ Peters, 1854 (2) + _Lissemys_ Smith, 1931 (1) + _Pelochelys_ Gray, 1864 (1) + _Trionyx_ Geoffroy, 1809 (14) + +_Dogania_ is considered a synonym of _Trionyx_ (Loveridge and Williams, +_op. cit._:422). + +_Geologic range._--Lower Cretaceous (possibly Upper Jurassic) to Recent +of Asia; Upper Cretaceous to Recent of North America; Paleocene (Upper +Jurassic, assuming _Trionyx primoevus_ is a trionychid) to Pleistocene +of Europe; Lower Miocene to Recent of Africa; Pleistocene to Recent in +East Indies (Loveridge and Williams, _op. cit._:412; Romer, 1945:594); +questionable trionychid fragments from Pleistocene of Australia +(Darlington, _loc. cit._). $/ + +_Remarks._--The genera _Lissemys_, _Cyclanorbis_ and _Cycloderma_ are +distinguished from _Pelochelys_, _Chitra_ and _Trionyx_ by several +characters (Loveridge and Williams, _op. cit._:414). The recognition of +two groups of genera caused Deraniyagala (1939:290) to erect two +families, Cyclanorbidae and Trionychidae. An appraisal of fossils +prompted Hummel (1929:768) to propose two corresponding subfamilies, +Cyclanorbinae and Trionychinae. Williams (1950:554) considered the two +groups as subfamilies (Lissemydinae and Trionychinae). + +Baur (1887:97) regarded the Trionychidae as constituting a separate +suborder distinct from the rest of the living turtles. Later (1891), +however, he pointed out the resemblances of the Trionychidae and +Carettochelyidae (having one living genus in New Guinea), and the +cryptodiran affinities of _Carettochelys_. Bergounioux (1932:1408) +mentioned the close resemblance of the Carettochelyidae to _Trionyx_ but +considered the former as having pleurodiran affinities, a view adopted +by Deraniyagala (_loc. cit._). Most students now consider the two +families to be closely related, and conceive of both as members of the +suborder Cryptodira (Hummel, 1929:768; Williams, _loc. cit._; Mertens +and Wermuth, 1955). + +The oldest trionychid fossil, _Trionyx primoevus_, is from marine +deposits of the Upper Jurassic (Kiméridgien) from "Cap de la Hève," and +its characters do not indicate the kind of cryptodiran ancestor from +which the family arose (Bergounioux, _op. cit._:1409; 1937:188). Lane +(1910:350) found that the entoplastron (= epiplastron) was paired in +embryos of _Trionyx_ and regarded that genus as the most primitive of +the order; he also mentioned Wiedersheim's report of rudiments of teeth +in embryos of _Trionyx_. Baur (1891:637-38) thought that the family +arose directly from the Amphichelydia, that the ancestors of the +Trionychidae closely resembled _Carettochelys_ in the structure of the +carapace and plastron, and that a progressive reduction in ossification +of those structures occurred. Nopcsa (1926:654) also wrote that the +family originated from ancestors having a well-developed plastron; he +maintained that the progressive reduction in ossification of the +plastron was a specialization for aquatic life, and that the more +primitive trionychids had the best developed bones and callosities. +Hummel (1929:772) also thought that there had been a progressive +reduction in ossification. Bergounioux (1932:1408; 1936:1088, +1952:2304), on the contrary, thought that there had been a progressive +increase in ossification of the marginal bones in both families as well +as of the plastron (1936:1088; 1937:190). Zangerl's study of the shell +elements of turtles (1939:393) indicated that _Trionyx_ was highly +specialized in having a well-developed epithecal armor (sculptured +callosities, neurals and costals), and that it occurred in most aquatic +turtles; the development in soft-shells suggested that members of the +family had maintained an aquatic mode of life over a long period of +geologic time, a view supported by Deraniyagala (1930:1066). Of interest +are Stunkard's remarks (1930:214-18) concerning several _Trionyx +spinifer_ that were obtained from a commercial supply house and found to +be infested with pronocephalid trematodes (_Opisthoporus_ [= +_Teloporia_] _aspidonectes_). The closest relatives of that trematode +(also recorded from _T. ferox_) live in marine turtles. Possibly, a +Mesozoic ancestor of marine and essentially fresh-water soft-shelled +turtles harboured ancestors of these trematodes, but possibly the +parasites may have transferred relatively recently to their present +hosts. Bergounioux (1937:190) judged the Trionychidae to be an ancient +group of marine origin. Hummel (1929:770) wrote that the Trionychidae +originated in east Asia (the region of most differentiation) in humid +climates. + +Baur (1891:634, 637) pointed out that the dorsal aspect of the skull of +the closely related _Carettochelys_ resembles the skull of the +Dermatemydidae, Staurotypidae and Kinosternidae; the close relationship +of _Carettochelys_ and the Dermatemydidae is also mentioned by +Bergounioux (1952:2304) and Hummel (1929:769). Hummel (_op. cit._:771) +thought that the Carettochelyidae and "die Chelydroiden" had a common +ancestor, and that (_op. cit._:772) the origin of the Trionychidae was +older than those two groups. Dunn (1931:109) wrote that the +Kinosternidae, Carettochelyidae and Dermatemydidae represented the same +general ancestry. Williams (1950:552) has shown the resemblance of the +cervical articulations in members of the Chelydridae (including +Staurotypinae and Kinosterninae) and the Central American family +Dermatemydidae. The consensus of opinion, then, is that the families +Trionychidae, Carettochelyidae, Chelydridae and Dermatemydidae are +relatively closely related. + + +Genus =Trionyx= Geoffroy, 1809 + + _Testudo_ Linnaeus (in part), Syst. Nat., Ed. 10, 1:197, 1758; type, + _Testudo graeca_ Linnaeus by subsequent designation (Fitzinger, + 1843:29). + + _Trionyx_ Geoffroy, Ann. Mus. Hist. Nat. Paris, 14:1, August, 1809; + type, _Trionyx aegyptiacus_ (= _Testudo triunguis_ Forskål) by + original designation. + + _Apalone_ Rafinesque, Atlan. Jour., Friend of Knowledge, + Philadelphia, 1 (No. 2, Art. 12):64, Summer, 1832; type, _Apalone + hudsonica_ (= _Trionyx spiniferus_ Lesueur) by monotypy. + + _Mesodeca_ Rafinesque, Atlan. Jour., Friend of Knowledge, + Philadelphia, 1 (No. 2, Art. 12):64, Summer, 1832; type _Mesodeca + bartrami_ (= _Testudo ferox_ Schneider) by monotypy. + + _Aspidonectes_ Wagler, Naturl. Syst. Amphib., p. 134, 1830; type, + _Aspidonectes aegyptiacus_ Wagler (= _Testudo triunguis_ Forskål) + by subsequent designation (Fitzinger, 1843:30). + + _Amyda_ Fitzinger, Ann. Wiener Mus. Naturg., 1:110, 120, 127, 1835; + type, _Amyda subplana_ Fitzinger by subsequent designation + (Fitzinger 1843:30). + + _Gymnopus_ Duméril and Bibron, Erpét. Gén., 2:472, 1835; new + (substitute) name for _Aspidonectes_ Wagler. + + _Pelodiscus_ Fitzinger, Ann. Wiener Mus. Naturg., 1:110, 120, 127, + 1835; type, _Pelodiscus sinensis_ Fitzinger by subsequent + designation (Fitzinger, 1843:30). + + _Platypeltis_ Fitzinger, Ann. Wiener Mus. Naturg., 1:109, 120, 127, + 1835; type, _Platypeltis ferox_ by subsequent designation + (Fitzinger, 1843:30). + + _Potamochelys_ Fitzinger, Syst. Rept., p. 30, 1843; type, + _Aspidonectes javanicus_ Wagler (= _Testudo cartilaginea_ + Boddaert) by original designation. + + _Tyrse_ Gray, Cat. Tort. Croc. Amphis. Brit. Mus., p. 48, 1844; + type, _Tyrse nilotica_ Gray (= _Testudo triunguis_ Forskål) by + tautonomy (_Tyrse_, a name for the Nile River). + + _Callinia_ Gray, Proc. Zool. Soc. London, p. 222, 1869; new + (substitute) name for _Aspidonectes_ of Agassiz (1857:403); type, + _Callinia spicifera_ (mispelling for _spinifera_) Gray by + subsequent designation (Stejneger, 1907:514). + + _Euamyda_ Stejneger, Bull. Mus. Comp. Zool., 94:7, 9, 12, 1944; new + (substitute) name for _Amyda mutica_ of Agassiz (1857:399); type, + _Amyda mutica_ Agassiz by monotypy. + +_Type Species._--_Trionyx aegyptiacus_ (= _Testudo triunguis_ +Forskål). + +_Diagnosis._--Cutaneous femoral valves absent; width of postorbital +arch of skull less than diameter of orbit; pterygoids usually not +contacting opisthotics; carapace lacking prenuchal bone and marginal +ossifications; nuchal bone lacking conspicuous ventral ridges; +posterior margin of nuchal overlying first pair of pleurals; lateral +parts of nuchal bone overlying second pair of ribs; neurals seven or +eight, rarely six or nine; pleurals seven or eight pairs, posterior +one or two pairs sometimes in contact medially; distinct suture +usually present between hyoplastra and hypoplastra; most laterad prong +of posteromedial process of hypoplastra inserted between bifid +anterolateral process of xiphiplastra. + +_Synonomy._--Geoffroy published a synopsis of the species he +recognized (1809) prior to his formal description of the genus +_Trionyx_ (1809a). Schweigger, nevertheless, probably was the first +person to recognize the soft-shelled turtles as a distinct group, and +he proposed for it the name _Amyda_ in an unpublished manuscript that +he sent to Geoffroy. The latter author (1809a:15) relegated the name +_Amyda_ to the synonomy of _Trionyx javanicus_ by means of the +following entry: "_Amyda javanica._ Schweigger, dans un manuscript +communique a l'Institut." Stejneger (1944:7) maintained that this +publication of Schweigger's monotypic generic name clearly established +its availability for the species congeneric with _Amyda javanica_ (= +_Testudo cartilaginea_ Boddaert, 1770). Loveridge and Williams +(1957:422) contend that this mere mention of the name _Amyda_ neither +constitutes the proposal of a new name nor validates it, and that the +first valid usage of the name _Amyda_ is that of Fitzinger (1835:120), +who later (1843:30) designated the type species as _Amyda subplana_. +The name _Amyda_ cannot date from _Oken_ (1816:348) as Volume 3 +[Zoologie] of his Lehrbuch der Naturgeschichte published in 1815-1816 +has been placed on the Official Index of Rejected and Invalid Works in +Zoological Nomenclature with the Title No. 33; see Opinion 417 +(Hemming, 1956). + +There has been considerable debate as to whether Geoffroy did or did +not designate a type species of the genus _Trionyx_ (1809a). Although +not specifically designated as the type species, _Trionyx aegyptiacus_ +(= _Testudo triunguis_ Forskål) is considered by Smith (1930:2), +Schmidt (1953:108, footnote), and Loveridge and Williams (1957:422) to +have been sufficiently indicated by Geoffroy as the type species. But +Stejneger (1944:6), H. M. Smith (1947:122), Conant and Goin +(1948:11), and Mertens and Wermuth (1955) maintained that Geoffroy did +not adequately designate a type species, and that Fitzinger (1843:30) +designated the type species as _Trionyx granosus_ (= _Lissemys +punctata_), a synonym of Geoffroy's species, _coromandelicus_. + +If Fitzinger's designation of a type species is accepted, the name +_Trionyx_ is applicable to the forms herein referred to _Lissemys_, +and _Amyda_ to the American forms. If Geoffroy's designation is +accepted, the American forms are referable to _Trionyx_, and _Amyda_ +is a synonym. + +The preceding includes only those generic names (listed in +chronological order) that have been applied to Recent American +soft-shelled turtles. Generic synonyms of the genus _Trionyx_ +applicable to Old World species are listed by Stejneger (1907:514), +Smith (1931:165), and Loveridge and Williams (1957:420-21). + +_Trionyx_ is the most widespread genus of the family; most of the +species occur in southeastern Asia. All North American soft-shelled +turtles belong to this genus. + +For quick reference, all the specific and subspecific names proposed +for soft-shelled turtles in North America are listed below in +alphabetical order (left hand column) with their nomenclatural status +as recognized in this paper. The synonyms are listed in the account of +the appropriate species or subspecies, and are discussed under the +subsection entitled "Remarks." + + _agassizi_ _Trionyx spinifer asper_ + _annulifer_ _Trionyx spinifer spinifer_ + _argus_ _Trionyx spinifer spinifer_ + _asper_ _Trionyx spinifer asper_ + _ater_ _Trionyx ater_ + _bartrami_ _Trionyx ferox_ + _emoryi_ _Trionyx spinifer emoryi_ + _calvatus_ _Trionyx muticus calvatus_ + _ferox_ _Trionyx ferox_ + _georgianus_ _Trionyx ferox_ + _georgicus_ _Trionyx ferox_ + _harlani_ _Trionyx ferox_ + _hartwegi_ _Trionyx spinifer hartwegi_ + _hudsonica_ _Trionyx spinifer spinifer_ + _mollis_ _Trionyx ferox_ + _microcephalus_ _Trionyx muticus muticus_ + _muticus_ _Trionyx muticus muticus_ + _nuchalis_ _Trionyx spinifer spinifer_ + _ocellatus_ _Trionyx spinifer spinifer_ + _olivaceus_ _Trionyx spinifer spinifer_ + _spiniferus_ _Trionyx spinifer spinifer_ + + +Variation + +Aside from qualitative variations and comparisons of patterns of +pigmentation the following external measurements (to the nearest +millimeter) were used. + +_Length of plastron_: Maximal straight-line measurement +(midventrally), from the anteriormost region of the ventral surface to +the posterior end of the plastron; this measurement includes an +anterior cartilaginous part. + +_Length of carapace_: Maximal, straight-line measurement +(middorsally), from the nuchal region to the posteriormost region of +the free edge of the carapace. + +_Width of carapace_: Maximal, straight-line measurement between the +lateral margins of the carapace. + +_Plane of greatest width of carapace_: Maximal, straight-line +measurement from the posteriormost region of the free edge of the +carapace to a point on the middorsal line at the level or plane of the +greatest width of the carapace; this measurement and the last two, of +course, include the fringing cartilaginous parts of the dorsal bony +carapace. + +_Width of head_: Maximal measurement between the lateral margins of +the head. + +_Length of snout_: Measurement from tip of snout to interorbital +region of least breadth. + +_Diameter of ocellus_: Maximal outside diameter of largest (not +conspicuously ovoid or oblong) ocellus on carapace. + +The following ratios were developed from the measurements. Reference +to these ratios will be made by the abbreviations within the +parentheses: length of carapace/length of plastron (CL/PL); length of +carapace/width of carapace (CL/CW); length of carapace/plane of width +of carapace (CL/PCW); length of plastron/width of head (PL/HW); width +of head/length of snout (HW/SL); diameter of ocellus/length of +plastron (OD/PL). + + +Secondary Sexual Variation + + +_Size_ + +In many species of turtles, females are larger than males; the +difference in size between the sexes is probably most pronounced in +aquatic emydids. The ten largest individuals of each sex were selected +to indicate the relative difference in size between the sexes of the +three American species of _Trionyx_ (excluding _ater_, Table 2). +Female soft-shelled turtles attain a larger size than males. _T. +ferox_ is the largest species; _muticus_ is the smallest. The +approximate maximal size of each sex and the difference in size +between the sexes are more correctly expressed for _spinifer_ and +_muticus_ than for _ferox_, because fewer specimens of _ferox_ were +examined; presumably the approximate maximal size of males and females +of _ferox_ is larger than is indicated in Table 2. + + TABLE 2. Secondary Sexual Difference in Maximal Size of North + American Species of the Genus Trionyx (excluding ater) Based + on the Ten Largest Specimens of Each Sex of Each Species. + The Extremes Precede the Mean (in parentheses). + + =============+============================ + SPECIES | Plastral length (cm.) + -------------+---------+------------------ + _ferox_ | males | 17.0-26.0 (20.0) + | females | 23.3-34.0 (27.9) + | | + _spinifer_ | males | 13.8-16.0 (14.4) + | females | 26.0-31.0 (28.0) + | | + _muticus_ | males | 11.8-14.0 (12.3) + | females | 17.7-21.5 (18.9) + -------------+---------+------------------ + + +_Pattern_ + +Secondary sexual differences in pattern are probably more pronounced +in soft-shelled turtles than in other species of turtles, except +perhaps for the well-known melanism and concomitant obliteration of +pattern acquired by some adult males of the _scripta_ section of the +genus _Pseudemys_. + +The difference in pattern between the sexes of American species varies +with size of the individual and with the species and subspecies. The +juvenal pattern of some individuals of _T. spinifer asper_ differs +according to sex. In the other species and subspecies, there are no +secondary sexual differences in the juvenal pattern. That pattern in +females of all species and subspecies is partly or entirely obscured +by a mottled and blotched pattern as growth proceeds. This mottled and +blotched pattern is present on females not yet sexually mature, and is +of contrasting lichenlike figures, and in other individuals is less +contrasting and a more uniform coloration. The largest males of _T. +spinifer_ retain a conspicuous juvenal pattern; in those of _muticus_ +the pattern may be well-defined or partly modified and obscured, +whereas in large males of _ferox_ the juvenal pattern is ill-defined +or absent. No male normally acquires a contrasting mottled and +blotched pattern on the carapace. The pattern on the carapace of many +large individuals of _ferox_ is not distinctive as to sex. + +On the dorsal surface of the soft parts of the body there is a +contrasting pattern in adult males and hatchlings of some forms, but +in most large females the pattern is usually reduced to a near-uniform +coloration; the pattern on adult males of _ferox_ and _muticus_ is not +contrasting and resembles that on large females. + + +_Coloration_ + +Because most specimens examined were preserved, the detection of +secondary sexual differences in coloration was difficult. There is one +difference in coloration between the sexes in the subspecies _T. s. +emoryi_. Males from the Río Grande drainage, at least those from the +Big Bend region of Texas, and southwestward in the Río Conchos into +Chihuahua, México, are bright orange on the side of head (postlabial +and postocular pale areas); an orange tinge also occurs in pale +stripes on the snout, and pale orange blotches sometimes occur on the +dorsal surfaces of limbs, especially the hind limbs. The coloration of +these areas on females is pale yellow, lacking orange. + + +_Tuberculation_ + +In all subspecies of _spinifer_ the carapace of adult males is +"sandpapery" owing to abundant, small, spiny tubercles distributed +over its surface; all females lack spiny tubercles on the surface of +the carapace. + + +_Length of Tail_ + +Elongation of the preanal region of the tail resulting in the +extension of the cloacal opening beyond the posterior edge of the +carapace occurs in males of several kinds of turtles, including +_Trionyx_, at least in those from Louisiana, Texas, and Lake Texoma, +Oklahoma (Webb, 1956:121). Probably this elongation is characteristic +of males of all American softshells. Some females of _spinifer_ and +_muticus_ that exceed the maximum size attained by males have the tip +of the tail and cloacal opening extending a short distance beyond the +posterior edge of the carapace. Some large females of _ferox_ have +more elongate tails than those of _spinifer_ and _muticus_. + + +_Width of Alveolar Surfaces of Jaws_ + +Stejneger (1944:34-36, pl. 6) commented on a series of large skulls of +_ferox_ mostly from Kissimmee, Florida, some of which had +conspicuously expanded alveolar surfaces. He suggested that the +condition was confined to large males. A scattergram (Fig. 2) based on +measurements obtained from 45 skulls of _ferox_ shows widened alveolar +surfaces of the upper jaws on some of the larger skulls. Because the +maximal size of adult males is unknown and the difference in size +between the sexes of _ferox_ is slight, such large skulls might +represent either sex. The sex had been recorded for only three of the +45 skulls; none of the three exceeded 82 millimeters in basicranial +length or had widened alveolar surfaces. Some of the larger skulls of +approximately the same size differ markedly in width of the alveolar +surfaces; this difference suggests that both sexes are included and +that the sexes may be of approximately the same maximal size. On the +other hand, the variation observed in skulls is possibly confined to +one sex. To judge from what is known of the maximal sizes of the sexes +of _spinifer_ and _muticus_ (see Table 2), skulls of _ferox_ of more +than 85 millimeters in basicranial length probably are of females. The +largest alcoholic male (dissected) of _ferox_ that I examined had a +width of head of approximately 46.5 millimeters; that measurement +corresponds to a basicranial length of 70 to 75 millimeters. The +specimen of which measurements are depicted by the uppermost symbol in +the scattergram (represented by KU 16528) was recorded as a female. +Large females of _T. s. asper_ from rivers emptying into the Atlantic +Ocean have broadened alveolar surfaces. + + [Illustration: FIG. 2. Basicranial length and greatest width of + alveolar surface of upper jaw on 45 skulls of _T. ferox_. Some + skulls (sex unknown) in which the basicranial length exceeds + 85 mm. develop widened alveolar surfaces of the jaws.] + +_Length of Claw_ + +Secondary sexual differences in length of claw on the forelimb are +pronounced in some kinds of turtles. Cahn (1937:178) stated that the +female of _Trionyx muticus_ usually has long claws on the hind feet, +while the male has long claws on the forefeet, but I am unable to +substantiate his statement. Measurements of length of the third claw +on the hind limb taken in 41 males and 45 females of _spinifer_ from +Louisiana showed no secondary sexual difference. + + +Ontogenetic Variation + + +_Pattern_ + +In all species and subspecies the juvenal pattern is replaced in +females as growth proceeds by a mottled and blotched pattern that is +contrasting or of nearly uniform coloration. The blotched pattern (of +lichenlike figures) is evident on the carapaces of most females that +have plastra so long as 8.0 centimeters. The contrasting juvenal +pattern on the dorsal surfaces of the soft parts of the body is +correspondingly modified in females, but at a size larger than 8.0 +centimeters. Size of ocelli (OD/PL) in _T. s. spinifer_ and _hartwegi_ +seems to vary ontogenetically (see section on Geographic Variation). + +Some hatchlings have blotched patterns (_T. spinifer asper_, TU +16689.2, plastral length, 3.5 cm.); the largest females examined that +did not show any evidence of mottling were two _asper_ having +plastrons 7.6 and 8.0 centimeters in length. Variation in color and +pattern probably is modified greatly by the environment (Heude _in_ +Stejneger, 1907:518, footnote d) and the physiological condition of +the individual. Smith, Nixon and Minton (1949:92) reported that a +female of _T. s. hartwegi_ developed a striking melanistic pattern in +captivity and they concluded that patterns of soft-shelled turtles may +be produced not only by conventional chromatophores, but also by other +depositions, both intra- and extracellular. TU 16170, taken from +brackish water at Delacroix Island, St. Bernard Parish, Louisiana, is +the only adult male I have seen that had a blotched pattern +(orange-brown in life) on the carapace in addition to the juvenal +pattern. One female of _muticus_, KU 48229, having a plastral length +14.5 centimeters, retained a well-defined juvenal pattern, and lacked +a mottled and blotched pattern (see Pl. 46). + + +_Tuberculation_ + +Males of the subspecies of _spinifer_ develop small, sharp tubercles +on the dorsal surface of the carapace when sexually mature. As growth +proceeds, the minute prominences along the anterior edge of the +carapace on hatchlings of both sexes of _spinifer_ change in shape to +conical projections or low, flattened, scarcely-elevated prominences, +depending on the subspecies (Fig. 8). + +Large females of _spinifer_ and _ferox_ acquire enlarged, flattened +knobs in the nuchal region and posteriorly in the center of the +carapace. + + +_Length of Tail_ + +The preanal region of the tail rapidly elongates in males of all +soft-shells when they are sexually mature. + + +_Width of Alveolar Surfaces of Jaws_ + +The alveolar surfaces of the jaws are conspicuously broadened in large +adults of _ferox_, and females of that population of _T. s. asper_ in +the Atlantic Coast drainage. + + +_Ratios_ + +Width of head increases at a rate slightly slower than does the length +of the plastron (PL/HW, Fig. 3). The change in proportions is most +pronounced at a plastral length of 7.5 to 8.0 centimeters. In +general, the head is narrowest in _muticus_ and widest in _ferox_. _T. +s. asper_ and _emoryi_ seemingly have the widest heads among the +subspecies of _spinifer_. Geographically width of head increases from +_spinifer_ and _hartwegi_ through _pallidus_ and _guadalupensis_ to +_emoryi_. _T. ater_ terminates the cline; 12 specimens, ranging in +plastral length from 9.6 to 18.4 centimeters, resemble _ferox_ and +_asper_ in having wide heads (average PL/HW of 4.93). + + [Illustration: FIG. 3. Ratio of length of plastron to width of head + (PL/HW) in some American species and subspecies of the genus + _Trionyx_. The size of each sample is given in parentheses + following an indication of the range (< = less than, > = greater + than) in length of plastron (in cm.) of each sample. The horizontal + line indicates the observed variation; the vertical line, the mean; + the white rectangle, four standard deviations; and the black + rectangle, four standard errors of the mean. There is some + ontogenetic variation in PL/HW. The head is narrowest in _muticus_ + and widest in _ferox_.] + + +The carapace increases in width more slowly than it increases in +length (CL/CW, Fig. 4). The change in proportions is most pronounced +when the carapace is 8.0 to 8.5 centimeters in length. Ontogenetically +_muticus_ varies least and _ferox_ most; large specimens of _ferox_ +have narrower carapaces than _muticus_ of corresponding size. There is +also an indication of a geographical gradient that parallels the cline +mentioned above for PL/HW. There is a gradual decrease in width of +carapace from _pallidus_ through _guadalupensis_ to _emoryi_. Of the +subspecies of _spinifer_, _emoryi_ has the narrowest carapace and +resembles _ferox_. In _T. ater_ this cline is accentuated and +terminates; 12 specimens, ranging in plastral length from 9.6 to 18.4 +centimeters, resemble _ferox_ and _emoryi_ in having narrow carapaces +(average CL/CW of 1.32). + + +_Osteological Characters_ + +Closure of the anterior, paravertebral fontanelles on the bony +carapace, and size and number of plastral callosities are subject to +ontogenetic variation (see sections entitled "Carapace" and +"Plastron"). + + [Illustration: FIG. 4. Ratio of length of carapace to width of + carapace (CL/CW) in some American species and subspecies of the + genus _Trionyx_. Symbols as in Fig. 3. There is some ontogenetic + variation in CL/CW (least in _muticus_). The carapace is + narrowest in _ferox_ and _emoryi_, and widest in _muticus_, + _pallidus_ and _asper_.] + + [Illustration: FIG. 5. Pattern on dorsal surface of snout of some + American species and subspecies of the genus _Trionyx_. Note the + gradual transition in pattern from that of _hartwegi_ (b) and + _asper_ (c) to that of _emoryi_ (h). + + a. _T. ferox_ (UMMZ 102276, × 1/3) + b. _T. spinifer hartwegi_ (KU 46742, × 3/4) + c. _T. spinifer asper_ (KU 50842, × 1) + d. _T. spinifer pallidus_ (KU 2958, × 1/2) + e. _T. spinifer pallidus_ (KU 2934, × 1/2) + f. _T. spinifer pallidus_ (KU 2947, × 1/2) + g. _T. spinifer guadalupensis_ (TU 10165, × 2/3) + h. _T. spinifer emoryi_ (KU 48218, × 2/3) + i. _T. muticus muticus_ (KU 48236, × 2/3) + ] + + +Geographic Variation + +Geographic variation occurs in _Trionyx spinifer_ and _T. muticus_. +The variant populations of _spinifer_ are segregated into six +subspecies, those of _muticus_ into two. In the subspecies of +_spinifer_ there is both group variation and clinal variation. + + +Group Variation + +The six subspecies of _spinifer_ can be separated into two groups on +the basis of the juvenal pattern. One group (subspecies _spinifer_, +_hartwegi_ and _asper_) has a pattern of dark spots or ocelli of +various sizes on the carapace, whereas the other group (subspecies +_pallidus_, _guadalupensis_ and _emoryi_) has a pattern of small white +dots or tubercles on the carapace. The two groups differ also in the +manner in which the mottled and blotched pattern first appears on the +carapace of females. Usually, contrasting lichenlike figures initially +surround the dark spots or ocelli on the carapace in females of the +_spinifer_ group (less evident in _pallidus_), whereas females of the +_emoryi_ group usually lack a contrasting pattern early in ontogeny. +In general, the two groups differ in the degree of pigmentation. The +_spinifer_ group has larger marks and more contrasting patterns on the +head and limbs, and more extensive pigmentation on the ventral surface +than members of the _emoryi_ group. _T. ater_ is more closely related +to those subspecies of the _emoryi_ group but differs in having the +ventral surface heavily speckled with black and an over-all blackish, +dorsal coloration; the underlying pattern of _ater_ resembles that of +_emoryi_. + + +Clinal Variation + +Several characters are arranged in a geographical gradient or cline. +Some characters are relatively uniform and represent a terminus in the +_spinifer_ group. Some characters change gradually and successively +through the subspecies _pallidus_ and _guadalupensis_, and terminate +in _emoryi_ and _T. ater_. Some characters of _ater_, in turn, show +affinity with _T. muticus_ and _T. ferox_. + + +_Pattern on Snout_ + +The pattern (Fig. 5) on the snout usually consists of pale, +dark-bordered stripes that form an acute angle in front of the eyes in +_spinifer_, _hartwegi_ and _asper_, but the corresponding marks form a +dark triangle the base line of which joins the anterior margins of the +orbits in _emoryi_ and usually in _guadalupensis_. In _pallidus_, the +geographic range of which is between _guadalupensis_ and _hartwegi_, +there are different patterns that are in various degrees intermediate +between those described immediately above for _hartwegi_ and +_guadalupensis_. + + +_Pattern on Side of Head_ + +The change in pattern (Fig. 6) and its contrast with the ground color +on the side of the head parallels the sequence of changes in pattern +on the snout. The pattern on the side of head contrasts with the +ground color and consists of dark markings below the eye and on the +neck, an indication of a postlabial stripe, and a pale, dark-bordered +postocular stripe that may be variously interrupted (_spinifer_ and +_hartwegi_; _asper_ usually has uninterrupted postocular and +postlabial stripes that unite on the side of the head). The pattern is +contrasting but variable in _pallidus_. _T. s. emoryi_ and usually +_guadalupensis_ have fewer dark markings, sometimes none, and an +interrupted postocular pale stripe that produces a pale blotch just +behind the eye. + + [Illustration: FIG. 6. Pattern on side of head of some American + species and subspecies of the genus _Trionyx_. Note the gradual + reduction in contrast of pattern and interruption of the postocular + stripe from that of _spinifer_ (b) to that of _emoryi_ (f). + + a. _T. ferox_ (UMMZ 102276, × 1/3) + b. _T. spinifer spinifer_ (UMMZ 54401, × 2/3) + c. _T. spinifer asper_ (KU 50843, × 2/3) + d. _T. spinifer pallidus_ (KU 50830, × 3/4) + e. _T. spinifer guadalupensis_ (SM 659, × 2/3) + f. _T. spinifer emoryi_ (KU 2922, × 3/4) + g. _T. muticus muticus_ (KU 48228, × 2/3) + h. _T. muticus calvatus_ (KU 47117, × 2/3) + ] + + [Illustration: FIG. 7. Pattern on the dorsal surface of the distal + part of the right hind limb of some American species and subspecies + of the genus _Trionyx_. Note the gradual reduction in contrast of + pattern from that of _hartwegi_ (a) to that of _emoryi_ (d). + + a. _T. spinifer hartwegi_ (KU 15932, × 3/4) + b. _T. spinifer pallidus_ (KU 40175, × 2/3) + c. _T. spinifer guadalupensis_ (TU 10165, × 3/4) + d. _T. spinifer emoryi_ (KU 3153, × 5/6) + e. _T. muticus muticus_ (KU 48228, × 3/4) + f. _T. ferox_ (UMMZ 102276, × 1/2) + ] + + [Illustration: FIG. 8. Shape of tubercles on anterior edge of + carapace in some American species and subspecies of the genus + _Trionyx_ (× 1/2). Note the gradual reduction in size of + tubercles from that of _hartwegi_ (b) to that of _muticus_ (h). + + a. _T. ferox_ (UMMZ 90010) + b. _T. spinifer hartwegi_ (KU 3346) + c. _T. spinifer pallidus_ (TU 13213) + d. _T. spinifer guadalupensis_ (TU 10160) + e. _T. spinifer emoryi_ (KU 2906) + f. _T. ater_ (KU 46906) + g. _T. muticus muticus_ (KU 48229) + h. _T. muticus muticus_ (KU 48232) + ] + +_Pattern on Dorsal Surface of Limbs_ + +A corresponding sequence of change occurs in the size of dark markings +on the dorsal surface of the limbs (Fig. 7). The hind limb usually has +larger markings than the forelimb. The change is gradual from larger +and darker markings (contrasting pattern) in _hartwegi_, _spinifer_ +and _asper_ to smaller and paler markings (non-contrasting pattern) in +_emoryi_. + + +_Tuberculation_ + +There is also a cline in tuberculation (Fig. 8) that parallels +geographically the sequence of changes in patterns mentioned +immediately above. The size of the tubercles along the anterior edge +of the carapace changes in both sexes from those that are enlarged and +equilateral or conical in shape in _spinifer_, _hartwegi_, _asper_ and +_pallidus_ to those that are scarcely elevated in _guadalupensis_, +_emoryi_ and _T. ater_. Indeed, in the three kinds mentioned last, the +tubercles are absent in some specimens. There seems to be a +corresponding reduction in the size and number of small, sharp-tipped +tubercles that cover the carapace in adult males; the carapace of _T. +ater_ is mostly smooth and has only a few small, whitish tubercles. + + [Illustration: FIG. 9. Anteroposterior position of plane of + greatest width of carapace (CL/PCW) in some American species + and subspecies of the genus _Trionyx_. Symbols as in Fig. 3. + The greatest width of carapace is midway between anterior and + posterior ends in _ferox_, _spinifer_, _hartwegi_, _asper_ and + _muticus_, and farther posterior in the other subspecies of + _spinifer_.] + + +_Ratios_ + +The clinal tendencies in PL/HW (Fig. 3) and CL/CW (Fig. 4) that +parallel those mentioned above for pattern and tuberculation have +already been mentioned under the section "Ontogenetic Variation." + +The ratio of CL/PCW (Fig. 9) was used in an effort to show further +differences in the shape of the carapace, especially the plane on the +carapace where the greatest width occurs. Figure 9 shows the greatest +width to be approximately midway between the anterior and posterior +ends in the subspecies _spinifer_, _hartwegi_ and _asper_, and in the +species _ferox_ and _muticus_ (CL/PCW of 2.00). The greatest width of +carapace is more posterior and at approximately the same plane in +_pallidus_ and _guadalupensis_, and farther posterior in _emoryi_. +Calculated ratios for 12 specimens of _T. ater_ average 2.15, a value +that suggests closer affinity with _pallidus_, _guadalupensis_ and +_emoryi_ than to the other species and subspecies. + +Comparison of the relative lengths of snout (HW/SL, Fig. 10) in +different populations of _T. spinifer_ shows a character gradient. To +facilitate a comparison utilizing large samples, the subspecies +_spinifer_ was combined with _hartwegi_, and _pallidus_ with +_guadalupensis_. The snout is longer in the subspecies _spinifer_ and +_hartwegi_ than in _emoryi_; the length of the snout of _emoryi_ +resembles that of _T. ferox_. The snout is proportionately the longest +in _T. muticus_. The average ratio of HW/SL for 12 individuals of _T. +ater_ is 1.37, and is nearer that of _pallidus_, _guadalupensis_, +_emoryi_ and _ferox_ than that of _muticus_ or the other subspecies of +_T. spinifer_. + + [Illustration: FIG. 10. Ratio of width of head to length of snout + (HW/SL) in some American species and subspecies of the genus + _Trionyx_. Symbols as in Fig. 3. Values for _spinifer_ are + combined with those of _hartwegi_, and those of _pallidus_ + with _guadalupensis_. The snout is proportionately the + longest in _muticus_.] + +Size of the ocelli increases from west to east in populations of _T. +spinifer_ in the upper Mississippi River and Great Lakes drainages. + +The ratio of OD/PL (Fig. 11) varies considerably but gradually +increases from Kansas northeastward to Michigan. The minimal diameter +of any ocellus recorded was one millimeter; solid dots on the carapace +(_hartwegi_) were also recorded as one millimeter. Larger ratios are +usually derived from measurements of larger individuals. Seemingly, +there should be a clinal tendency in ontogenetic variation paralleling +the size of ocelli and dependent on it; ontogenetic variation should +be least in western populations in which the size of ocelli does not +change appreciably with increasing size, and should be greatest in +eastern populations in which the ocelli on adult males are larger than +those on the carapace of young turtles. It is difficult to +demonstrate ontogenetic variation because specimens of corresponding +size from the same general area may have ocelli of different sizes. +The gradient in size of ocelli is also indicated by specimens from +other states. I have the subjective impression that there is least +variation in specimens from Michigan (Great Lakes-St. Lawrence River +drainage), but this is not clearly shown by Figure 11. + + [Illustration: FIG. 11. Ratio of diameter of ocellus to length of + plastron (OD/PL) in _T. spinifer_ from some states in the upper + Mississippi River and Great Lakes drainages. Symbols as in + Fig. 3. The size of the ocelli on the carapace gradually + increases from Kansas northeastward to Michigan.] + + +Character Analysis + + +_Snout_ + +The snout (Fig. 12) is tubate having terminal nostrils separated by a +vertical septum. One of the principal characters distinguishing _T. +ferox_ and _T. spinifer_ from _T. muticus_ is a lateral, whitish ridge +projecting from each side of the nasal septum (hereafter referred to +as septal ridges but often referred to in the literature as a +papilla). The shape of the end of the snout is truncate in _T. ferox_ +and _T. spinifer_, and the nostrils are larger than in _T. muticus_. +In _muticus_ the snout usually terminates somewhat obliquely, and the +nostrils tend to be slightly inferior; also, the end of the snout is +usually rounded and somewhat pointed, causing the nostrils to be +visible in lateral view. Some _T. muticus_ do not differ markedly from +_ferox_ or _spinifer_ in shape of the end of the snout. Stejneger +(1944:14) mentioned indication of a septal ridge that did not reach +the opening of the nostril in _muticus_. I have slit the outer edge of +the nostril on several specimens of _muticus_, and have not noticed an +indication of a septal ridge. + + [Illustration: FIG. 12. Shape of snout in _T. spinifer_ (left, a-d, + from KU 46907) and _T. muticus_ (right, e-h, from KU 48236). + Lateral views--a, e (× 1); anterior views--b, f (× 5); dorsal + views--c, g (× 2.5); ventral views--d, h (× 2.5).] + + +_Tuberculation_ + +Tubercles or obtuse prominences occur on the anterior edge of the +carapace (Fig. 8) or on the dorsal surface of the carapace. _Trionyx +muticus_ lacks tubercles, although some individuals show shallow, +widely spaced wrinkles that suggest prominences on the anterior edge +of the carapace. Both sexes of _T. ferox_ have prominences, resembling +flattened hemispheres, on the anterior edge of the carapace and in the +nuchal region. Large females of _ferox_ have obtuse prominences in the +center of the carapace posteriorly, some of which are often arranged +in longitudinal rows. The surface of the carapace in both sexes of _T. +ferox_ has small closely-set, blunt tubercles arranged in rows that +resemble longitudinal ridges (most evident in juveniles). + +Large females of _T. spinifer_ have obtuse prominences in the center +of the carapace posteriorly, some of which in many specimens are +arranged in longitudinal rows; I cannot discern any correlation of +number or arrangement of prominences with size in _spinifer_ or +_ferox_. The carapace in adult males of _spinifer_ bears small, sharp +tubercles that make the surface feel like sandpaper. The tubercles on +the anterior edge of the carapace in adults of both sexes vary from +round to equilateral and conical to low and flattened (see comments on +tuberculation under subsection entitled "Geographic Variation"). Some +large females of the same subspecies have tubercles on the anterior +edge of the carapace that may be conical (higher than wide) or +equilateral. The difference in shape of the tubercles seems not to be +correlated with size because one _T. s. pallidus_, 30.5 centimeters +(TU 13212) has prominent but blunted and equilateral tubercles, +whereas, another female of _pallidus_, 20.8 centimeters (TU 13210), +from the same locality has higher, conical tubercles. The blunted, +equilateral tubercles may be the result of environmental wear, or the +difference in shape of tubercles may be due to individual variation. + + +_Pattern on Carapace_ + +Two features of the pattern on the carapace are of taxonomic worth: 1) +the width and distinctness of the pale rim at the periphery of the +carapace (marginal rim), if present, and 2) the kind of pattern on the +carapace (juvenal pattern). The marginal rim is absent in females of +_T. ater_, and only faintly evident in males. The marginal rim is +obscured or absent (adult males and females) and is not separated from +the ground color of the carapace by a dark marginal line in hatchlings +of _T. ferox_. The carapace of _T. muticus_ has a marginal rim that is +usually separated from the ground color of the carapace by an +ill-defined, dark marginal line; some individuals lack the marginal +dark line. The subspecies of _T. spinifer_ have a well-defined, dark, +marginal line that separates the marginal rim from the ground color of +the carapace; _T. s. asper_ has more than one dark marginal line on +the carapace. The marginal rim is ill-defined and blotched, or absent, +in large females of all species of _Trionyx_. + +The marginal rim is widest at the posterior end of the carapace and +lacking in the nuchal area. The width of the pale marginal rim is very +narrow, almost to the degree of being absent, in juveniles of _T. +ferox_. _T. s. emoryi_ has a pale, marginal rim that is four or five +times wider posteriorly than it is laterally, whereas posteriorly the +width of the rim in the other subspecies of _T. spinifer_ and in the +species _T. muticus_ is only two or three times wider posteriorly than +it is laterally. + +The juvenal pattern commonly consists of whitish tubercles or dots +(_T. s. emoryi_, _T. s. guadalupensis_, _T. s. pallidus_, _T. ater_), +large black ocelli (_T. s. spinifer_), small black dots and ocelli +(_T. s. hartwegi_, _T. s. asper_), large dusky spots or ocelli (_T. m. +calvatus_), or small dusky dots or short streaks and dashes (_T. m. +muticus_). Some hatchlings of _pallidus_ and _emoryi_ have a uniform +pale brown or tan carapace; hatchlings of _T. ferox_ have a +distinctive pattern (Pl. 31). Further comments and illustrations +pertaining to kind of pattern on the carapace are offered under the +accounts of species and subspecies. + + +_Pattern on Dorsal Surface of Snout (Fig. 5)_ + +_T. ferox_ has pale stripes on a dark background that unite in front +of the eyes; the dark ground color becomes paler with increasing size, +but the stripes retain thick black borders. _T. m. muticus_ has +ill-defined, pale stripes that are evident just in front of the eyes +and do not extend anteriorly to unite in front of the eyes, whereas +_T. m. calvatus_ lacks pale stripes on the snout. The kind of pattern +on the dorsal surface of the snout that is characteristic for each of +the subspecies of _T. spinifer_ has been mentioned in the discussion +of clinal variation. + + +_Pattern on Side of Head (Fig. 6)_ + +_T. ferox_ has a pale broad, postocular stripe in contact with the +orbit or not, and other pale marks on a dark background; the ground +color becomes paler with increasing size, but the stripes and other +marks retain thick black borders. _T. m. muticus_ usually has an +uninterrupted, dusky-bordered, postocular stripe, whereas _T. m. +calvatus_ (in adult males only) has pale postocular stripes with thick +blackish borders. The pattern on the side of head that is +characteristic for each subspecies of _T. spinifer_ has been mentioned +in the discussion of clinal variation. + + +_Pattern on Dorsal Surface of Limbs (Fig. 7)_ + +Young specimens of _T. ferox_ have pale marks on a blackish +background. As growth proceeds the distinctive contrasting pattern is +obliterated and eventually is replaced by a uniform grayish coloration +in large adults. The pattern on the limbs of _T. muticus_ is not +contrasting, and is almost a uniform grayish, consisting of fine, pale +markings. The clinal variation in pattern and kind of pattern on the +limbs of the subspecies of _T. spinifer_ has been mentioned in the +discussion of clinal variation. Dark markings tend to form streaks +that are coincident with the digits, and larger markings occur on the +hind limbs than on the forelimbs. + + +_Marginal Ridge_ + +The anterolateral edge of the carapace in _T. ferox_ (both sexes and +all sizes) is "folded over" into a ridge having a distinct inner +margin (Pls. 1 and 2), which is hereafter referred to as the marginal +ridge. Siebenrock (1924:184-85) referred to this ridge as a +"Hautsäume" and mentioned its occurrence in Old World species of the +genus _Trionyx_. The marginal ridge is not present in _T. muticus_, +_T. spinifer_ or _T. ater_. + + +_Ratios_ + +The means of some samples (Fig. 3) differ in regard to PL/HW, but the +ranges of variation overlap so much that little significance can be +attributed to the difference. _T. ferox_, and to a lesser extent _T. +s. emoryi_ and _T. s. asper_, have slightly larger heads than the +other forms. The width of head is proportionately the smallest in _T. +muticus_; in most individuals of it having a plastron so long as 13.0 +centimeters, the width of the head is less than 16 per cent of the +length of the plastron--a percentage that is distinctive. + +The visibly narrower carapace (CL/CW, Fig. 4), suggesting an ovoid or +oblong shape, in some large individuals of _T. ferox_ and _T. s. +emoryi_ is indicated by the large ratio in specimens that have a +plastral length of 8.0 centimeters or more. Nevertheless, the degree +of overlap of the ranges of variation is such that this ratio is of +relatively little use taxonomically. + +The greatest width of the carapace is farther posterior in _T. s. +emoryi_ than in the other forms (CL/PCW, Fig. 9). The considerable +overlap of the range of variation of this ratio for _emoryi_ with the +other forms limits its usefulness as a taxonomic character. + +The snout is proportionately shortest in _ferox_ and _T. s. emoryi_, +and longest in _muticus_ (HW/SL, Fig. 10). The most marked difference +in this ratio is between the species _muticus_ and _ferox_; the ranges +of variation of those species overlap to a degree that tends to negate +the taxonomic usefulness of this character. + +Most adults and subadults of _T. ferox_ show clearly in dorsal view +the anterolateral portions of the plastron. This condition is much +less well developed in some specimens of _T. s. emoryi_. _T. ferox_ is +extreme in the ratio CL/PL (relatively the longest plastron or +shortest carapace, Fig. 13). _T. s. asper_ has the shortest plastron +in relation to length of carapace. Calculated ratios for 12 _T. ater_ +average 1.36, a value that suggests close affinity with some +subspecies of _T. spinifer_ (_pallidus_, _guadalupensis_, _emoryi_). +Because of the degree of overlap of the ranges of variation in all +forms, little significance can be attributed to the difference in +means of _ferox_ and _asper_. + + [Illustration: FIG. 13. Ratio of length of carapace to length of + plastron (CL/PL) in some American species and subspecies of + the genus _Trionyx_. Symbols as in Fig. 3. _T. ferox_ has + proportionately the shortest carapace.] + + +_Scalation_ + +Cornified, smooth or cusplike areas occur on each limb, but their +number and arrangement are of no taxonomic value. Normally, the +anterior surface of each forelimb possesses four cornified areas for +which the term antebrachial scales is proposed (Fig. 14). Two of the +four scales occur in a more dorsal position; the lateral edge of the +proximal one is free and cusplike along a part of its length, whereas +the distal scale is smooth-edged. Two scales having their lateral +edges free and cusplike are ventral in position, and closer together +than the two dorsad scales. Size of the scales and length of the free +cusplike edges vary. Occasionally adjacent scales are fused or small +additional scales are present. The number, configuration and +arrangement of the two cornified areas on each hind limb are constant. +One of these scales is smooth-edged and occurs posteriorly on the +dorsal surface. The other scale, situated on the ventral surface +posteriorly in the region of the heel and distal to the smooth-edged +scale of the dorsal surface, has a pronounced, cusplike, free edge. + + [Illustration: FIG. 14. Dorsal surface of right forelimb showing + normal number and arrangement of antebrachial scales in American + species of the genus _Trionyx_ (_T. spinifer hartwegi_, + KU 15932, × 3/4).] + + +_Choanal Papillae_ + +This term refers to the papillate flaps of skin that project from the +lateral borders of the internal nares. Webb and Legler (1960:23) noted +their presence in softshells, and Parsons (1958) discussed their +occurrence in sea turtles of the family Cheloniidae and in the +testudinid subfamily Emydinae (1960). In preserved softshells the +choanal papillae may extend laterally and partly cover the nares, or +may be folded vertically against the lateral borders of the nares; in +the latter position the papillae are easily overlooked. To my +knowledge, choanal papillae occur in all American species and +subspecies of soft-shelled turtles. The free edge of each narial flap +shows various degrees of fimbriation. The fimbriated border is least +developed (margin nearly entire) in _T. muticus_ and most developed in +_T. ater_ and _T. ferox_. In _ater_ at least, the anteriormost +portions of the narial flaps seem wider than in the other forms and +show a greater degree of fimbriation than the posteriormost parts. The +choanal papillae are most easily observed in large specimens. + + +_Skull_ + +In general, there is less difference between the skulls of _ferox_ and +_spinifer_ than between either of those species and _muticus_ +(Stejneger, 1944:10-11). Figure 15 shows the general differences in +proportions of the skulls of _spinifer_ and _muticus_; Plate 54 shows +the skull of the holotype of _Platypeltis agassizi_ (= _T. s. asper_), +which is similar to that of _ferox_; Stejneger (_op. cit._) provided +labelled drawings of the skull of _T. spinifer_ as well as photographs +of skulls of other forms. + +The total of 159 skulls examined by me include 80 of _spinifer_, 50 of +_ferox_, and 29 of _muticus_. There are no secondary sexual +differences between skulls of corresponding size, except in +_agassizi_-form skulls mentioned under the account of _T. s. asper_, +and possibly in _ferox_. Most, and possibly all, of the skulls of +_muticus_ having a basicranial length of 40.0 millimeters or more, and +those of _spinifer_ exceeding 50.0 millimeters must represent females +(by correlation of known maximum size of males with greatest width of +head, which is, in turn, compared with the greatest width of skull and +corresponding basicranial length). + + [Illustration: FIG. 15. Skulls of _Trionyx spinifer hartwegi_ (left, + a-d, KU 2757), and _Trionyx muticus muticus_ (right, e-h, KU 1870). + Dorsal views, a (× 1/2), e (× 3/4); occipital views, b (× 5/6), + f (× 1); lateral views, c (× 1/2), g (× 3/4); ventral views, + d (× 1/2), h (× 3/4). + + a., alveolar surface of upper jaw + aq., articular surface of quadrate + ex., exoccipital + fp., fenestra postotica + fm., foramen magnum + if., intermaxillary foramen + ic., internal choana + mx., maxilla + mxb., maxillary bridge + oc., occipital condyle + op., opisthotic + ope., opisthotic-exoccipital spur + opw., opisthotic wing + pmx., premaxillaries (fused) + pt., pterygoid + q., quadrate + qj., quadratojugal + sq., squamosal + s., supraoccipital spine + tc., tympanic cavity + ] + +Measurements used include basicranial length (occipital condyle to tip +of upper jaw), greatest width (variable in position), greatest width of +alveolar surface of maxilla (taken at level immediately posterior to +anterior margin of internal choanae), greatest length of internal +choanae, and least breadth of maxillary bridge (separating internal +choanae and intermaxillary foramen). One ratio developed from the +measurements was greatest length of internal choanae/least breadth of +maxillary bridge, hereafter referred to as IC/MB. This ratio is +discussed under the account of _T. s. asper_. + + +_Greatest Width_ + +The position or level on the skull where the greatest width (Table 3) +occurs is of some diagnostic value in distinguishing the skulls of +_ferox_ from _spinifer_ and _muticus_. Skulls of _ferox_ usually are +widest at the level of the quadratojugal (immediately in front of +tympanic cavity), whereas skulls of _spinifer_ and _muticus_ usually +are widest slightly more posteriorly at a level on the squamosal +immediately behind the tympanic cavity. Occasionally the width at the +level of the quadratojugal and squamosal is the same, or the greatest +width of skull may be ventrad between the quadrates, which are +slightly flared laterally. The latter condition possibly is most +prevalent in _muticus_. + + TABLE 3. Variation in Position of Greatest Width of Skull of North + American Species of the Genus Trionyx (excluding ater). The Number + of Specimens Examined (in Parentheses) Follow the Specific Names. + + ================+================================================= + | Species + POSITION +--------------+-----------------+---------------- + | _ferox_ (36) | _spinifer_ (47) | _muticus_ (14) + ----------------+--------------+-----------------+---------------- + Squamosal | 7 (19%) | 35 (74%) | 11 (79%) + Quadratojugal | 26 (72%) | 7 (15%) | 1 (7%) + Quadrate | 2 (6%) | | 2 (14%) + Squamosal and | | | + quadratojugal | | | + of same width | 1 (3%) | 5 (11%) | + ----------------+--------------+-----------------+---------------- + + +_Supraoccipital Spine_ + +The ventral surface of the supraoccipital spine in _muticus_ lacks a +medial ridge, and gradually increases in width anteriorly, so that it +is widest proximally in the region of the roof of the foramen magnum. +In _ferox_ and _spinifer_, the ventral surface, usually having a +medial ridge, is narrow and of the same width throughout its length or +somewhat flared distally. The ventral surface of the supraoccipital +spine, which is widest proximally in _muticus_, is always narrow +proximally in _ferox_ and _spinifer_. The ventral surface of the +supraoccipital spine of one skull of _spinifer_, USNM 91311, differs +little from that of _muticus_. + + +_Foramen Magnum_ + +The shape of the foramen magnum is generally rhomboidal in _spinifer_ +and _ferox_; the ventral angle is semicircular, the lateral angles +obtuse, and the dorsal angle more acute. The shape of the foramen +magnum in _muticus_ is ovoid, higher than wide; the sides are evenly +rounded. + + +_Opisthotic-Exoccipital Spur_ + +Skulls of _spinifer_ normally have the fenestra postotica partly +restricted by a medially-slanting, descending spur from the roof of +the fenestra postotica; the spur incorporates the suture between the +exoccipital and opisthotic and includes parts of those two bones. On +one skull (KU 2824) the spur is displaced more medially and does not +incorporate the opisthotic. The descending spur contacts the pterygoid +ventrally forming a complete bony strut traversing the fenestra +postotica in some skulls (KU 2228, 2666, 2762, TU 15423, MCZ 46621, TU +15415, right side only). The fenestra postotica on skulls of _ferox_ +and especially _muticus_ is not normally restricted by an +opisthotic-exoccipital spur. + +Often the spur is reduced and indicated by a smooth projecting ridge. +Sometimes the spur or ridge is absent on skulls of _spinifer_, and I +have seen no well-developed spur on a skull of _muticus_. The +development of the spur is not due to ontogenetic variation. There is +some variation in development of the spur on either side of the skull; +two skulls of _ferox_ have the combination ridge/absent, and two of +_spinifer_ have the combinations ridge/spur and spur/absent. The +frequency (based on counts of individual skulls) and the degree of +development of the spur among the three species is indicated in Table +4. + + TABLE 4. Frequency and Degree of Development of Opisthotic + Exoccipital Spur of North American Species of the Genus Trionyx + (excluding ater). The Number of Specimens Examined (in Parentheses) + Follow the Specific Names. + + ======================+================================================= + | Species + DEVELOPMENT OF SPUR +--------------+-----------------+---------------- + | _ferox_ (43) | _spinifer_ (68) | _muticus_ (29) + ----------------------+--------------+-----------------+---------------- + spur (well-developed) | 1 (2%) | 45 (66%) | + ridge (reduced) | 7 (16%) | 20 (30%) | 1 (3%) + absent | 35 (82%) | 3 (4%) | 28 (97%) + ----------------------+--------------+-----------------+---------------- + +Loveridge and Williams (1957:415, footnote) cited Siebenrock who +mentioned a descending process of the opisthotic in _Dogania_ (= +_Trionyx_) _subplana_ and _Trionyx sinensis_. I have not seen an +ascending process of the pterygoids on skulls of American softshells +as described by Loveridge and Williams (_op. cit._:414, 429, fig. 54) +for _Lissemys_, _Cyclanorbis_, _Cycloderma_ and some _Trionyx +triunguis_. + + +_Opisthotic Wing_ + +This term refers to the laterally directed, posterior part of the +opisthotic that is visible in occipital, lateral and ventral views. In +ventral view the opisthotic wing is most easily seen and is wider in +_muticus_ than in _spinifer_ or _ferox_. In _muticus_ the distal part +is truncate, whereas in _ferox_ and _spinifer_, it is more tapered and +gently rounded, although somewhat unevenly flared medially. Also +there is more of a downward curvature (in ventral view) of the +opisthotic wing in _muticus_ than in _ferox_ or _spinifer_; +consequently the tip of the wing in _muticus_ is often just visible in +dorsal view (on lateral side of squamosal), certainly in lateral view. +The distal part or tip of the opisthotic wing is not visible in dorsal +view on skulls of _ferox_ or _spinifer_. + + +_Articular Surface of Quadrate_ + +The ventral surface of the quadrate that articulates with the mandible +is composed of a lateral condyle and a medial articular surface. The +condyle and medial articular surface are separated by a furrow. On +skulls of _ferox_ and _spinifer_ the lateral condyle, which is not +conspicuously tapered posteriorly, is slightly larger than the medial +articular surface, and the furrow is shallow. On skulls of _muticus_, +the lateral condyle is conspicuously tapered posteriorly, is slightly +smaller than the medial articular surface, and the furrow is deep. + + +_Contact of Maxillaries Above Premaxillaries_ + +The contact of the maxillaries above the premaxillaries is of +diagnostic value in distinguishing skulls of _ferox_ and _spinifer_ +from those of _muticus_. I have seen no skulls of _muticus_ on which +the maxillaries were in contact, and no skulls of _ferox_ on which the +maxillaries were separated. Stejneger (1944:19), however, reported a +skull of _muticus_ (USNM 102677) having the maxillaries in contact. +Maxillaries are in contact (sometimes just barely) in 65 of 74 skulls +of _spinifer_ (88%); the premaxillaries are separated on nine skulls +(12%). + + +_Carapace_ + +The dorsal surface of the bony carapace of American trionychids +consists of a nuchal, seven or eight pairs of pleurals, and seven or +eight, rarely nine, neurals (Fig. 16). The lateral parts of the nuchal +overlie the second pair of ribs. The distal parts of the second +through the ninth pair of ribs extend laterally beyond the lateral +edges of the pleurals. There are no marginal ossifications. The +posterior part of the bony carapace bears blunt, rounded or ovoid to +linear, prominences mostly on the last pair of pleurals principally on +large females of _spinifer_ and _ferox_; I have seen only one adult +male (stuffed, MCZ 46633) having a semblance of welts on the bony +carapace. The nuchal, pleurals and neurals are sculptured. + +As growth proceeds, the single, transversely-oriented, fontanelle of +young turtles that separates the nuchal from the first neural and +first pair of pleurals divides into two fontanelles that generally +decrease in size and finally disappear. Occasionally only one +(unilateral) large fontanelle is present (USNM 54734, _muticus_). The +largest specimens noted that retain fontanelles are a _ferox_ (USNM +029474) having a plastron 24 centimeters long, and a _spinifer_ (USNM +54731) having a plastron 20 centimeters long. The fontanelles probably +are present in some larger individuals. + + [Illustration: FIG. 16. Carapace of _Trionyx spinifer_ (a), and + sketches of posterior parts of carapaces (b-i) of three American + species, showing number and variation in arrangement of neurals and + pleurals (not to scale; seventh neural, n7, and pleural, p7). + + a. KU 2226, Lewisville, Lafayette County, Arkansas (× 1/3); + sculpturing incompletely shown. Labels: r, ribs; nu, nuchal; n, + neurals 1-7; p, pleurals 1-7. + + b. _ferox_, USNM 60496, Auburndale, Polk County, Florida. + + c. _muticus_, KU 1964, Doniphan Lake, Doniphan County, Kansas. + + d. _spinifer_, USNM 100380, Plaquemine, Iberville Parish, + Louisiana. + + e. _muticus_, TCWC 7260, Red River, 8 mi. NW Ringgold, Montague + County, in Clay County, Texas. + + f. _spinifer_, USNM 59266, Homer, Winona, Minnesota. + + g. _muticus_, KU 2840, White River, DeValls Bluff, Prairie County, + Arkansas. + + h. _muticus_, USNM 115939, Mississippi. + + i. _muticus_, USNM 54734, Mississippi River, Fairport, Muscatine + County, Iowa. + ] + +Most variation concerns the number of neurals and pairs of pleurals, and +their arrangement posteriorly (H. M. Smith, 1947:121, table; Stejneger, +1944:18). Table 5 shows the frequency of occurrence of the number of +neurals, pairs of pleurals, and the separation or contact of the seventh +pair of pleurals; figure 16 illustrates some of the configurations of +these plates posteriorly (e, g, and i not included in Table 5). The +eighth pair of pleurals is reduced or absent (Loveridge and Williams, +1957:417). Eight neurals and eight pairs of pleurals occur in all three +species. The seventh pleurals may contact each other in all three +species, and their separation has been observed only in the species +_spinifer_ and _muticus_. Seven neurals and contact of the seventh pair +of pleurals, or eight neurals and separation of the seventh pair of +pleurals from each other occurs with approximately equal frequency in +the species _muticus_. _T. ferox_ and _spinifer_ most often have seven +neurals, seven pairs of pleurals, and the seventh pair of pleurals in +contact. Stejneger (_loc. cit._) mentioned a specimen in MCZ having nine +neurals; I recorded nine neurals for USNM 54734 (Fig. 16i) for which +Stejneger (_loc. cit._) recorded eight. AMNH 57384 (_ferox_) has a small +eighth pleural on the left side only, and USNM 115939 (_muticus_) has an +eighth pleural only on the right side (Fig. 16h). Anomalous conditions +observed included: an accessory bone between the first and second +pleurals on the right side that contacts the first and second neurals in +USNM 54733, (_muticus_); only six neurals in USNM 95193 (_spinifer_); a +small accessory bony element between the first and second neurals in +AMNH 57383 (_ferox_); and, only six pleurals (second and third fused) on +the right side in USNM 54734 (_muticus_). + + TABLE 5. Frequency of Occurrence of Number of Neurals, Pairs of + Pleurals, and Separation or Contact of the Seventh Pair of + Pleurals Among Species of American Soft-shell Turtles + + ===================+=================+================================== + Number | Contact (+) or | Species + --------+----------+ separation (-) +---------+------------+----------- + | Pairs of | of seventh pair | _ferox_ | _spinifer_ | _muticus_ + Neurals | pleurals | of pleurals | (16) | (60) | (34) + --------+----------+-----------------+---------+------------+----------- + 7 | 7 | + | 9 (56%) | 50 (83%) | 13 (38%) + 7 | 8 | + | 5 (31%) | 2 (3%) | 2 (6%) + 8 | 7 | + | 2 (13%) | 3 (5%) | 3 (9%) + 8 | 8 | + | | 4 (7%) | 2 (6%) + 8 | 7 | - | | 1 (2%) | 14 (41%) + --------+----------+-----------------+---------+------------+----------- + +Ventrally, the bony carapace shows ten thoracic vertebrae, the second +through the ninth having well-developed, depressed ribs that are fused +(no sutures) to the pleurals. The ribs of the first thoracic vertebra +are represented by bony struts that extend posterolaterally and +contact the anterior borders of the second pair of ribs. The two ribs +of the ninth pair are free for most of their length and often are +broken; they are slightly shorter than the eighth pair of ribs. The +ribs of the tenth thoracic vertebra may be well-developed (KU 2219, +2666, 50856, _spinifer_, and 16528, _ferox_), but are usually broken +off and represented only by transverse processes. + + +Kyphosis + +Kyphosis (angular curvature of the vertebral column) or the +hump-backed condition in American softshell turtles has been +summarized by Nixon and Smith (1949:28). Cahn (1937:185, pl. 25e) +illustrated the condition in an individual of _T. spinifer_, and H. +M. Smith (1947:119) mentioned kyphotic softshells representing the +species _spinifer_ (subspecies _hartwegi_ and _emoryi_) and _muticus_. +Neill (1951:10) mentioned two kyphotic _T. s. asper_ and Nixon and +Smith (_loc. cit._) recorded the report of a kyphotic _T. ferox_. I +have noted the condition in four _muticus_ (subspecies _muticus_, KU +1959-60, 23230; INHS 2148) and seven _spinifer_ (CNHM 22925; +subspecies _hartwegi_, USNM 55689; subspecies _spinifer_, UMMZ 52948, +95615; subspecies _emoryi_, KU 2219, 33523, TU 16240). The smallest +kyphotic specimen, a hatchling, TU 16240, has a plastral length of 3.5 +centimeters. Kyphosis is to be expected in all kinds of softshells as +are other abnormalities, such as albinism (reported for _Lissemys_ by +D'Abreu, 1928, and partial albinism noted in _T. cartilagineus_ by +Mohr, 1929) or congenital absence of limbs (reported by Dutta, 1931, +as occurring in the genera _Trionyx_ and _Lissemys_). The cause of +kyphosis is not known. Smith (_op. cit._:120) suggested an abnormally +early fusion of the costals (= pleurals) with the ribs, and a +subsequent differential rate of growth between them and the vertebral +column as a hypothesis; Williams (1957:236) proposed that late +retraction of the yolk mass, or retraction of an excessively large +yolk mass may cause kyphosis. The cause of kyphosis may be of genetic +origin or due to some environmental damage to the vertebral column +prior to the cessation of growth. The variation in rate of growth of +the vertebral column may produce humps of different shapes and sizes. +Some of the specimens noted above (UMMZ 52948, 95615) have the +carapace only slightly arched and are considered partly kyphotic. +There seem to be degrees of kyphosis, a fact that should be taken into +account in considering the occurrence of variation in greatest depth +of shell. + + +Plastron + +The plastron is united to the carapace by ligamentous tissue and is +somewhat flexible anteriorly and posteriorly. Anteriorly the plastron +is somewhat hingelike and may contact the anteriormost edge of the +carapace. The bony elements are reduced. There is usually a median +vacuity, which is relatively smaller in larger specimens and may be +divided into two vacuities (a posteromedial and an anteromedial) by +the medial juxtaposition of the hyo-hypoplastra, especially in +_muticus_. Williams and McDowell (1952) have recommended a change in +nomenclature for some of the plastral bones on the basis of +reinterpretation of their homologies. The nine plastral bones include: +an anterior pair of preplastra (= epiplastra, _auct._); an unpaired, +median bone, representing fused epiplastra (= entoplastron, _auct._), +hereafter referred to as the epiplastron; a pair of hyoplastra; a pair +of hypoplastra; and, posteriorly, a pair of xiphiplastra (Fig. 17). + +Siebenrock's (1902) synopsis of living trionychids was based entirely +on plastral characters. He distinguished between _muticus_ and +_spinifer_ principally by the shape of the epiplastron; _T. ferox_ was +not considered different from _spinifer_. The median angle formed by +the boomerang-shaped epiplastron is obtuse and somewhat greater than +90 degrees in _muticus_ (Fig. 17a); the angle of the epiplastron in +_spinifer_ and _ferox_ is smaller than in _muticus_ and forms an +approximate right angle (Fig. 17b). Williams and McDowell (_op. +cit._:277, Pl. 1, Fig. 3) presented an illustration of the anterior +plastral elements of an adult _T. ferox_. Siebenrock provided +illustrations of the plastrons of _muticus_ (_op. cit._:823, Fig. 5) +and _spinifer_ (_op. cit._:830, Fig. 10). + + [Illustration: FIG. 17. Plastron of _Trionyx muticus_ (a) and _T. + spinifer_ (b); sculpturing of callosities incompletely shown. ep, + epiplastron; hp, hyoplastron; hyp, hypoplastron; pp, preplastron; + xp, xiphiplastron. a--KU 1868, White River, Devall's Bluff, Prairie + County, Arkansas (× 2/3); b--KU 1869, same locality (× 2/3).] + +Much importance has been credited to the fusion (no suture) or +separation (suture present) of the hypoplastra and hyoplastra. The +fusion of these bones distinguishes the genera _Lissemys_, _Cyclanorbis_ +and _Cycloderma_ from _Trionyx_, _Pelochelys_, and _Chitra_ (Siebenrock, +_op. cit._:815, 817; Loveridge and Williams, 1957:415). This character +is also one of the criteria used by Hummel (1929: 768) in his erection +of the two subfamilies Cyclanorbinae (= Lissemyinae) and Trionychinae. +In my examination of specimens this character, unfortunately, was not +given full attention. I have noted the fusion of the hypoplastra and +hyoplastra in KU 1878 (_muticus_, right side only), KU 2219 (kyphotic +_spinifer_), KU 16528 (_ferox_) and KU 60121 (_ferox_). Dr. Ernest E. +Williams informs me in a letter of November 17, 1959, that of six +specimens of _ferox_ in the MCZ, the hyoplastra are fused with the +hypoplastra in three (54689-90, 54686). I suspect that these bones in +the three American species of the genus _Trionyx_, especially in +_ferox_, fuse more often than is supposed. + +In _muticus_ the constricted part of the hyoplastron and hypoplastron is +wider anteroposteriorly than in _spinifer_ or _ferox_ (Fig. 17). + +The three American species have on the hyoplastra, hypoplastra, and +xiphiplastra well-developed callosities, which enlarge with increasing +size. The medial borders of the hyoplastral and hypoplastral callosities +in larger specimens are rounded and closely approximated, often +touching, as do the callosities of each xiphiplastron; seemingly, the +callosities are relatively larger in _muticus_ than in _spinifer_ and +_ferox_. I have seen one adult male _muticus_ (KU 41380) that lacked +median fontanelles or vacuities owing to the contact of the plastral +elements (as viewed through overlying skin, alcoholic specimen). The +bony plastron (approximately 9 cm. in maximal length) of a small +_muticus_ (KU 19460) resembles the plastron of larger individuals of +_muticus_ in having well-developed hyoplastral and hypoplastral +callosities that are closely approximated medially. Large individuals of +_muticus_ usually have small, ovoid callosities on the preplastra, and a +well-developed, angular callosity on the epiplastron (Fig. 17a). +Siebenrock (_op. cit._:823) suggests that the presence of callosities on +the preplastra and epiplastron of _muticus_ is subject to individual +variation. I can not substantiate or dispute the supposition of Baur +(1888:1122), Siebenrock (1924:193) and Stejneger (1944:12, 19) that the +callosities are larger in males of _muticus_ than in the females. Some +individuals of _spinifer_ have seven plastral callosities (KU 2842) as +does _muticus_, but the callosities on the preplastra and epiplastron +are less frequent and less well-developed in large specimens of +_spinifer_ than in _muticus_. The small epiplastral callosity in +_spinifer_ is located at the medial angle and does not extend +posterolaterally to cover the entire surface of the epiplastron as it +may in _muticus_ (Fig. 17b). The epiplastron of a _spinifer_ (KU 2826) +has a medial callosity and another on the right posterolateral +projection; three separate callosities occur on the epiplastron of MCZ +46615. The last specimen mentioned, a large, stuffed female, possesses a +round, intercalary bone that tends to occlude the posteromedial vacuity. +Seemingly, the callosity on the epiplastron appears prior to those on +the preplastra; I have not seen any plastra having callosities on the +preplastra and lacking a callosity on the epiplastron. I have not noted +callosities on the preplastra or epiplastron of specimens of _ferox_. + +The callosities on the plastral bones are sculptured; small, recently +formed callosities on the preplastra and epiplastron lack sculpturing. +The pattern of sculpturing on the plastral bones as well as that of the +carapace is generally of anastamosing ridges. I am unable to discern any +differences in pattern of sculpturing between the three American +species. Stejneger distinguished adult specimens of _ferox_ from the +other American species by the coarseness of the sculpture of the bony +callosities (1944:24) and of the bony carapace (_op. cit._:32). The +sculpturing on the plastral callosities and carapace seems to be +correlated with size; larger specimens (_ferox_) have coarser +sculpturing than do smaller specimens (_muticus_). Stejneger also +mentioned that the sculpturing on many specimens of _ferox_ is +specialized into prominent, longitudinal welts (_loc. cit._); these +welts occur also on the carapace of _spinifer_. + +On the basis of the osteological characters examined by me, _T. muticus_ +is distinguished from _spinifer_ and _ferox_ by a number of characters +(plastron and especially skull) whereas the species _spinifer_ and +_ferox_ are not easily distinguished from one another. + + +Composition of the Genus _Trionyx_ in North America + +Analysis of the characters previously mentioned and their geographic +distribution permits the recognition of ten taxa, comprising four +species and eight subspecies. Two subspecies, _T. spinifer_ pallidus +and _T. s. guadalupensis_ are described as new. The four species and +the included subspecies here recognized are: + + _Trionyx ferox_ + _Trionyx spinifer spinifer_ + _hartwegi_ + _asper_ + _emoryi_ + _guadalupensis_ + _pallidus_ + _Trionyx ater_ + _Trionyx muticus muticus_ + _calvatus_ + +The following key is designed to permit quick identification of living +individuals; therefore, ratios and osteological characters are avoided +as much as possible in favor of other characters that are the least +variable and most "typical." Because there is considerable variation +correlated with sex and size, each taxon occurs in the key in more +than one couplet. Large females having mottled and blotched patterns +will be the most difficult to identify. The characters listed should +be used in combination because one character alone may not be +sufficient; it is advisable to read both choices of each couplet. The +text, figures and illustrations should be consulted for final +identification. + + + + +ARTIFICIAL KEY TO NORTH AMERICAN SPECIES AND SUBSPECIES OF THE GENUS +TRIONYX + + 1. Septal ridges present; tubercles on anterior edge of + carapace present or absent 2 + + Septal ridges absent; anterior edge of carapace lacking + tubercles or raised prominences 19 + + 2. Plastral area a uniform dark slate or blackish; soft + parts of body blackish having large pale marks dorsally; + carapace having large black blotches, often fused along + margin, on pale background, and many well-defined + longitudinal ridges _ T. ferox_, p. 479 + + Combination of characters not as above; ventral + surface whitish, blackish flecks or blotches + sometimes present 3 + + + 3. Carapace having pattern of white dots, or black ocelli + and/or spots; carapace sometimes gritty resembling + sandpaper 4 + + Carapace uniform pale brownish or grayish, or having + mottled and blotched pattern, contrasting or not; white + dots or tubercles, black ocelli and/or spots may be + present; carapace not gritty 10 + + 4. Carapace having pattern of black ocelli and/or spots; + numerous, conspicuous whitish spots or tubercles absent 5 + + Carapace having pattern of white dots that are sometimes + surrounded by small black ocelli; small black dots may be + interspersed among larger white dots 7 + + 5. Carapace having two or more marginal lines, these often + diffuse and interrupted; black spots sometimes ocellate + or bacilliform, or interspersed among smaller black dots; + postocular and postlabial stripes usually united + _spinifer asper_, p. 502 + + Carapace having only one dark marginal line; pattern of + black ocelli or spots; postocular and postlabial stripes + usually not united 6 + + 6. Carapace having prominent ocelli, which are much larger + near the center than at the sides + _spinifer spinifer_, p. 489 + + Carapace having numerous small, dark spots, sometimes + small ocelli, which are not much larger near the center + than the sides _spinifer hartwegi_, p. 497 + + 7. White spots on anterior third of carapace; white spots + on carapace often surrounded by narrow blackish ocelli; + small black dots sometimes interspersed among white spots + _spinifer guadalupensis_, p. 517 + + White spots absent on anterior third of carapace, or + small and inconspicuous; white spots not surrounded + by narrow blackish ocelli 8 + + 8. Pale rim of carapace narrow, partly obscured; over-all + dorsal coloration (including soft parts of body) dark and + lacking pattern; few, small, white tubercles confined to + posterior third of carapace _ater_, p. 528 + + Pale rim distinct, without markings; soft parts of body + dorsally not uniformly dark; many white tubercles + usually contrasting on pale carapace 9 + + 9. White spots confined to posterior third of carapace; + ground color of carapace usually pale brown or tan, + sometimes darker; a dark, slightly curved, line + connecting anterior margins of orbits; postocular stripe + usually interrupted leaving pale, blotch behind eye; + pale rim of carapace four or five times wider + posteriorly than laterally _spinifer emoryi_, p. 510 + + Small white spots on posterior half of carapace gradually + decreasing in size anteriorly, often indistinct or absent + on anterior third of carapace; pale rim of carapace no + more than three times wider posteriorly than laterally + _spinifer pallidus_, p. 522 + + 10. Marginal ridge present; carapace having ill-defined + dark blotches on uniform grayish, lacking whitish + tubercles or well-defined black spots or ocelli; pale + rim of carapace absent; tubercles on anterior edge of + carapace resembling flattened hemispheres; anterior + parts of plastron often visible in dorsal view; + postocular stripe, if present, having thick, blackish + borders _ferox_, p. 479 + + Marginal ridge absent 11 + + 11. Carapace uniform pale brownish, lacking mottled and + blotched pattern, white dots, black ocelli or spots 12 + + Carapace having mottled and blotched pattern, + contrasting or not; white spots or tubercles, black + ocelli or spots may be present 13 + + 12. Pale rim of carapace four or five times wider + posteriorly than laterally; dark, straight or slightly + curved, line connecting anterior margins of orbits + _spinifer emoryi_, p. 510 + + Pale rim of carapace no more than three times wider + posteriorly than laterally _spinifer pallidus_, p. 522 + + 13. Rear margin of carapace usually roughened by fine + corrugations, edge often ragged; pale rim absent; + carapace having dark brown-blackish, mottled and + blotched pattern; anterior edge of carapace more or + less smooth having scarcely elevated prominences; + posterior part of plastral area and especially ventral + surface of carapace having numerous black marks + _ater_, p. 528 + + Rear margin of carapace smooth, edge entire; + usually some evidence of pale rim 14 + + 14. White, rounded tubercles or spots usually evident + posteriorly on carapace, sometimes indistinct; black + ocelli or spots lacking in center of carapace, + sometimes present at sides; shape of tubercles on + anterior edge of carapace variable 15 + + White spots or tubercles absent; margin of carapace + usually having black ocelli or spots; tubercles on + anterior edge of carapace equilateral or conical, + not low and flattened 17 + + 15. White spots often present on anterior half of carapace; + tubercles on anterior edge equilateral and wartlike, + or less elevated, not conical + _spinifer guadalupensis_, p. 517 + + White spots usually absent on anterior half of + carapace, sometimes indistinct; shape of tubercles + on anterior edge of carapace variable 16 + + 16. White spots absent on anterior half of carapace; + tubercles on anterior edge of carapace low, scarcely + elevated, never equilateral or conical; mottled and + blotched pattern often not contrasting; ground color of + carapace sometimes dark; pale rim of carapace four or + five times wider posteriorly than laterally; dark, + straight or slightly curved, line connecting anterior + margins or orbits _spinifer emoryi_, p. 510 + + White spots sometimes indistinct on carapace, or few, + small spots present on posterior half of carapace; + tubercles on anterior edge of carapace equilateral and + wartlike or conical; mottled and blotched pattern usually + contrasting; pale rim less than three times wider + posteriorly than laterally _spinifer pallidus_, p. 522 + + 17. Carapace having evidence of more than one dark marginal + line, and scattered, black spots or ocelli + _spinifer asper_, p. 502 + + Carapace having only one, dark, marginal line 18 + + 18. Carapace having small black spots, lacking large + interrupted ocelli _spinifer hartwegi_, p. 497 + + Carapace having small black spots interspersed among + larger, interrupted ocelli _spinifer spinifer_, p. 489 + + 19. Carapace having pattern of dusky spots, sometimes + short lines 20 + + Carapace lacking pattern of dark spots or lines, + having a mottled and blotched pattern 21 + + 20. Pattern of circular spots, lacking short lines or + bacilliform marks; spots sometimes slightly ocellate; + no pale stripes on snout _muticus calvatus_, p. 539 + + Pattern of dots, or dots and short lines; pale + stripes on snout, at least just in front of eyes + _muticus muticus_, p. 534 + + 21. Mottled and blotched pattern usually contrasting; + ill-defined, blackish blotch absent behind eye + _muticus muticus_, p. 534 + + Mottled and blotched pattern usually not contrasting; + ill-defined, dark blotch may be present behind eye + _muticus calvatus_, p. 539 + + + + +Systematic Account of Species and Subspecies + + +=Trionyx ferox= (Schneider) + +Florida Softshell + +Plates 31 and 32 + + _Testudo ferox_ Schneider, Naturg. Schildkr., p. 330, 1783 (based + on Pennant, Philos. Trans. London, 61 (Pt. 1, Art. 32): 268, + pl. 10 [figs. 1-3], 1772). + + _Trionyx ferox_ Schwartz, Charleston Mus. Leaflet, No. 26:17, + pls. 1-3, May, 1956. + + _Testudo mollis_ Lacépède, Hist., Nat. Quadr. Ovip. Serp., 1:137, + pl. 7, 1788. + + _Testudo_ (_ferox_?) verrucosa Schoepff, Hist. Testud., Fasc. 5 + (Plag. M):90, pl. 19, 1795. + + _Testudo bartrami_ Daudin, Hist. Nat. Rept., 2:74, pl. 18, fig. 2, + 1801. + + _Trionyx georgicus_ Geoffroy, Ann. Mus. Hist. Nat., Paris, 14:17, + August, 1809. + + _Mesodeca bartrami_ Rafinesque, Atlan. Jour., Friend Knowledge, + Philadelphia, 1 (No. 2, Art. 12):64, Summer, 1832. + + _Trionyx harlani_ Bell in Harlan, Medic. Phys. Research, p. 159, + 1835. + +_Type._--Holotype, British Museum (Natural History) 1947.3.6.17; original +number 53A, presumably that of Royal Society; stuffed adult female and skull; +obtained from the Savannah River, Georgia, by Dr. Alexander Garden. + +_Range._--Southern South Carolina, southeastern Georgia, and all of Florida +except the Keys and perhaps the western end of the panhandle (see map, Fig. +18). + +[Illustration: FIG. 18. Map of southeastern United States showing geographic distribution +of _Trionyx ferox_.] + +_Diagnosis._--Marginal ridge present; longitudinal rows of tubercles that +resemble ridges on carapace of hatchlings; plastron often extending farther +forward than carapace in adults; plastral area dark slate or gray in hatchlings; +juvenal pattern of large slate or blackish blotches (often with pale centers) +on a pale background; pale outer rim of carapace (absent on adults) narrow, +not separated from ground color of carapace by distinct, dark line. + +Size large; head wide; carapace relatively long and narrow; snout short; +greatest width of skull at level of quadratojugal; often no suture between +hypoplastra and hyoplastra; callosities on epiplastron and preplastra usually +lacking. + +_Description._--Plastral length of smallest hatchling, 2.9 centimeters (UMMZ +95613), of largest male, 26.0 centimeters (AMNH 63642), of largest female, +34.0 centimeters (UMMZ 38123). + +Septal ridges present; over-all coloration of carapace and plastron, and soft +parts of body of hatchlings slate or blackish; carapace having blackish, circular +blotches, usually fused at margin, often with pale centers on buff background +forming coarse reticulum; pale, narrow rim of carapace not separated from +ground color by dark marginal line; pale rim, coincident with marginal ridge, +absent from anteriormost nuchal region; longitudinal rows of tubercles on +carapace resembling ridges; undersurface blackish, usually having posterior part +of carapace pale with irregular blackish marks; blackish soft parts of body +dorsally having large, pale markings, most consistent of which are postocular +mark that may contact orbit, postlabial mark that curves around angle of jaws, +inverted Y on top of snout, and one or two streaks on side of neck. + +Over-all coloration of adults grayish, paler than in hatchlings; carapace gray +sometimes having slightly darker, large, irregular markings; mottled and +blotched pattern on females not contrasting; sex of many large individuals not +distinguishable on basis of pattern on carapace; pale rim of carapace obscure or +absent; soft parts of body dorsally gray or brownish on large adults of both +sexes, sometimes having slightly paler, large markings; small adult males usually +having contrasting pattern on head; surface of carapace smooth (not "sandpaper") +on adult males; undersurface whitish, throat often grayish; well-defined +marginal ridge; anterior edge of carapace laterally to region of insertion +of forelimbs studded with low, flattened tubercles resembling hemispheres, never +conical; carapace usually having blunted tubercles, best developed anteriorly +and posteriorly on midline, but sometimes linearly arranged, resembling ridges, +especially at margins; anterolateral parts of plastron often extending farther +forward than corresponding parts of carapace. + +Range in length (in cm.) of plastron of ten largest specimens of each sex +(mean follows extremes), males, 17.0-26.0, 20.0; females 23.3-34.0, 27.9; +ontogenetic variation in PL/HW, mean PL/HW of specimens having plastral +lengths 6.5 centimeters or less, 3.52, and exceeding 6.5 centimeters, 4.87; +ontogenetic variation in CL/CW, mean CL/CW of specimens having plastral +lengths 8.0 centimeters or less, 1.18, and exceeding 8.0 centimeters, 1.30; mean +CL/PCW, 2.01; mean HW/SL, 1.44; mean CL/PL, 1.26. + +Jaws of some skulls that exceed 75 millimeters in basicranial length having +expanded alveolar surfaces; greatest width of skull usually at level of quadratojugal +(72%); ventral surface of supraoccipital spine narrow proximally, usually +having medial ridge; foramen magnum rhomboidal; opisthotic-exoccipital spur +absent (82%), sometimes indicated by ridge (16%); distal part of opisthotic wing +tapered, not visible in dorsal view; lateral condyle of articular surface of quadrate +larger than medial articular surface, not tapered posteriorly; maxillaries in contact +above premaxillaries; usually a combination of seven neurals, seven pairs +of pleurals, and contact of seventh pair of pleurals (56%), often eight pairs of +pleurals (31%); angle of epiplastron forming approximate right angle; often no +suture between hypoplastra and hyoplastra; callosities on preplastra and epiplastron +usually lacking. + +_Variation._--Crenshaw and Hopkins (1955:19) stated that in specimens from +Lake Okeechobee and southward the carapace is wider relative to the width of +the head, and Neill (1951:19) quoted Allen's observations that _ferox_ from southern +Florida "average larger and darker than those collected farther north." + +Carr (1952:417) reported that the pale reticulum on the carapace is yellowish +olive, the markings on head are yellow on an olive ground color, some +markings more orange, and the plastron slate gray. Duellman and Schwartz +(1958:271) mentioned that the carapace of hatchlings is edged in orange +grading to yellow posteriorly and has a pattern of bluish-black blotches on a +dull brown background, whereas the carapace is dull brown or blackish on +adults. Neill (_op. cit._:18) wrote "that the head stripes and the marginal +ring of the 'carapace' are orange rather than yellow (yellow at the time of +hatching, however)." + +The transition from the dark coloration of hatchlings to the paler coloration +of adults is gradual and subject to individual variation. The loss of +dark color ventrally occurs first on the plastral area, then the hind limbs, forelimbs, +posterior part of carapace and last on the neck and throat. The soft +parts of the body dorsally are gray or dark gray, and do not become so pale +as the ventral surface. The smallest specimen that I have seen displaying the +dark features of the hatchlings is a male, 7.7 centimeters (UMMZ 100673); +a female, 9.5 centimeters (UMMZ 110987), is the smallest specimen having +a whitish plastral area. The change from dark to pale coloration on the ventral +surface occurs at a size of 8.0 to 9.0 centimeters. The largest specimens I +have seen having indistinct, dusky blotches of the underside of the carapace +are a female, 11.3 centimeters (UMMZ 100836), and a male, 16.0 centimeters +(UMMZ 106322). A contrasting pattern on head and limbs, and a +dark throat are still evident in a female 19.2 centimeters (UMMZ 106302). + +_Comparisons._--_Trionyx ferox_ can be distinguished from all other species +of the genus in North America by the presence of a marginal ridge, longitudinal +ridges of tubercles on the carapace of juveniles (less evident in adults), +and the unique juvenal pattern and coloration. The lack of a juvenal pattern +and a smooth surface on the carapace (not gritty like sandpaper) distinguish +adult males from those of _T. spinifer_. Most adults of both sexes can be distinguished +from _spinifer_ and _muticus_ by the extension of the plastron farther +forward than the carapace (developed to a slight degree in some specimens +of _T. s. emoryi_). Both sexes of all ages can be distinguished from _muticus_ by +the presence of knoblike tubercles on the anterior edge of the carapace, and +septal ridges. + +_T. ferox_ is the largest species in North America; the maximum size of the +plastron in adult males is approximately 26.0 centimeters (16.0 in _spinifer_) +and of adult females, 34.0 centimeters (31.0 in _spinifer_). The head is wider +in _ferox_ than in _muticus_ and most subspecies of _spinifer_ (closely approached +by _asper_, _guadalupensis_, _emoryi_ and _T. ater_). The carapace is narrower in +_ferox_ than in _muticus_ and most subspecies of _spinifer_ (closely approached by +_emoryi_ and _T. ater_). The snout is shortest in _ferox_, but almost as short in +_T. s. emoryi_ and _T. ater_. _T. ferox_ has proportionately the longest plastron in +relation to length of carapace. + +Most skulls of _ferox_ differ from those of _muticus_ and _spinifer_ in having the +greatest width at the level of the quadratojugal (as do some _T. s. asper_; see +account of that subspecies). In the skull, _ferox_ resembles _spinifer_ but differs +from _muticus_ in having the 1) ventral surface of the supraoccipital spine narrow +proximally, and usually having a medial ridge, 2) foramen magnum rhomboidal, +3) distal part of opisthotic wing tapered, 4) lateral condyle of articular +surface of quadrate not tapered posteriorly, and larger than medial articular +surface, and 5) maxillaries in contact above premaxillaries. _T. ferox_ resembles +_muticus_ but differs from most individuals of _spinifer_ in lacking a well-developed +opisthotic-exoccipital spur. _T. ferox_ resembles _spinifer_ but differs from +_muticus_ in having the epiplastron bent at approximately a right angle; _ferox_ +differs from both _muticus_ and _spinifer_ in lacking a callosity on the epiplastron +and probably in the more frequent fusion of the hyoplastra and hypoplastra. + +_Remarks._--The early taxonomic history of _Trionyx ferox_ has been discussed +in detail by Stejneger (1944:27-32), who explained that Dr. Alexander +Garden of Charleston, South Carolina, sent a description and specimen of +_T. ferox_ to Thomas Pennant, and at the same time sent another specimen with +drawings to a friend, John Ellis, in London. Pennant presented one of the +specimens and drawings and the description to the Royal Society of London +in 1771; the description was published in 1772 and included Garden's drawings. +Because two specimens were involved the possibility exists that the +description (text, drawings and type specimen) is a composite based on two +specimens. + +I have not seen the type. Garden's original description (_in_ Pennant, 1772:268-271) +leaves little doubt that the text subject is a large adult female of _ferox_ +(see especially the statements, "fore part, [of carapace] just where it covers the +head and neck, is studded full of large knobs, [and] The under, or belly plate, +... is ... extended forward two or three inches more than the back +plate, ..."). I am indebted to Mr. J. C. Battersby, British Museum (Natural +History), Department of Zoology (Reptiles), for information concerning +the type and for comparing it with the text description and three figures published +by Pennant. The carapace of the type is approximately 16 inches long, +13-1/2 inches wide, and has low, flattened, knoblike tubercles along the anterior +edge. Some inaccuracies on the part of the artist (such as five claws on both +feet on the right side of Fig. 3, and four claws on the left front foot of Fig. 2 are +evident), and slight changes in the proportions of the type would have occurred +after death and preservation. It is the opinion of Mr. Battersby that the type, +text description and three figures represent one specimen. Figures 1 and 2, +dorsal and ventral views respectively, probably represent the same specimen +from life; the neck is withdrawn and the tail tip is visible in dorsal view, but +concealed beneath the posterior edge of the carapace in ventral view. Presumably +the same specimen (probably drawn from dried and stuffed animal) +is depicted in Figure 3 (dorsal view); the neck is fully extended and a large +part of the thick, pyramidal tail is visible in dorsal view. British Museum (Natural +History) 1947.3.6.17 is considered a holotype. The three figures published +by Pennant have been duplicated by Schoepff (1795:Pl. 19) and Duméril and +Bibron (1835:482). To my knowledge, the holotype was first specifically designated +as the "(Type.)" of _T. ferox_ by Boulenger (1889:259). The skull of the +holotype is figured by Stejneger (1944:Pl. 5). + +Garden did not list a specific locality for the two specimens that he sent to +London, but did mention that the turtle was common in the Savannah and +Altamaha rivers (of Georgia), and rivers in east Florida. Boulenger (_loc. cit._) +stated that the locality of the holotype was "Georgia." Baur (1893:220) restricted +the type locality to the "Savannah river, Ga." Neill (1951:17), who +believed _T. ferox_ to be absent from the Savannah River, changed the type +locality of _ferox_ to east Florida. Schwartz (1956:8) reappraised the status of +softshells in Georgia and Florida and reëstablished the Savannah River (at +Savannah), Georgia, as the type locality of _T. ferox_. + +Pennant failed to use binomial nomenclature when he published the type +description of Garden. The first name-combination (_Testudo ferox_) was proposed +by Schneider (1783:220). + +Lacépède (1788:137, Pl. 7) referred to Garden's description in Pennant +only as "The Molle" but on a folded paper chart entitled "Table Méthodique +des Quadrupèdes ovipares," which is inserted after an introduction of 17 pages, +listed _T. mollis_; this name is again listed on another folded chart, entitled +"Synopsis methodica Quadrupedum oviparorum," which is inserted between +pages 618 and 619 under the genus _Testudo_. The illustration (Pl. 7) was +taken from Pennant (Duméril and Bibron, _loc. cit._). The type locality has +been designated "(following Stejneger, 1944) as eastern Florida" by Schmidt +(1953:108). + +Bartram failed to use a binomial name with his description of "the great +soft shelled tortoise," which appeared in his _Travels_ (1791:177-179, Pl. 4 and +unnumbered plate between pages 282 and 283) and two editions of a French +translation (1799 and 1801, 1:307); see Harper (1940). Recently, Bartram's +_Travels_ has been placed on the Official Index of Rejected and Invalid Works +in Zoological Nomenclature, Opinion 447 (see Hemming, 1957). Bartram's +description of a soft-shelled turtle has provided the basis for the proposal of +at least three name-combinations. The first was _Testudo_ (_ferox?_) _verrucosa_ +proposed in 1795 by Schoepff; it appeared simultaneously in _The Historia +Testudinum_ and in a German translation, _Naturgeschichte der Schildkröten_ +(see Mittleman, 1944:245). Stejneger (1944:26) listed the type locality as +eastern Florida. Daudin (1801:74), also referring to Bartram's description +in his _Voyage_ (French translation), proposed the name _Testudo bartrami_; +Harper (_op. cit._:717) restricted the type locality of _T. bartrami_ from "Halfway +pond," east Florida, to southwestern Putnam County between Palatka +and Gainesville, Florida. Rafinesque (1832:64-65), relying on the authenticity +of the illustrations in Bartram's _Travels_ that depict a soft-shelled turtle +having five claws on each of the hind feet, tubercles on the sides of the head +and neck, and ten scales in the middle of the carapace (presumably inaccuracies +or a composite on the part of the artist), referred to Bartram's description as +a new genus, _Mesodeca bartrami_, a name which Boulenger (1889:245, footnote) +referred to as "mythical." Geoffroy (1809a:18-19) considered Bartram's +description the basis for the recognition of a second species of _Chelys_ (binomial +nomenclature not employed), and Duméril and Bibron (_loc. cit._) suggested +that the description was based partly on a "Chelyde Matamata." +The descriptive comments of Bartram are not clearly applicable to _Testudo +ferox_ Schneider; _Trionyx ferox_, however, is the only species of soft-shelled +turtle known to occur in the region of Bartram's observations (east Florida), +and the type locality was restricted to Putnam County, Florida, by Harper. +The name-combinations, _Testudo___ (_ferox?_) _verrucosa_ Schoepff, _Testudo bartrami_ +Daudin, and _Mesodeca bartrami_ Rafinesque are junior synonyms of _Testudo +ferox_ Schneider. + +Schweigger (1812:285) referred _ferox_ to the genus _Trionyx_ following the +description of that genus by Geoffroy in 1809. _Testudo ferox_ was listed as a +synonym by Geoffroy in the description of _Trionyx georgicus_ (1809a:17); +Duméril and Bibron (1835:432) mentioned that the specific characters of +_georgicus_ were taken from Pennant. The name _Trionyx georgianus_ presumably +appears for this taxon in Geoffroy's earlier-published synopsis (1809:367). +_T. georgicus_ was listed as occurring in rivers of Georgia and the Carolinas; +the type locality was restricted by Schmidt (_op. cit._:109) to the Savannah +River, Georgia. The two specific names _georgicus_ and _georgianus_ are regarded +as substitute names and junior synonyms of _T. ferox_. + +Geoffroy (1809a:14-15) also described _Trionyx carinatus_, a name-combination +that hitherto has been considered a synonym of _Trionyx ferox_. There +is no indication from the description that _carinatus_ is applicable to _ferox_. +Most comments pertain to a description of the bony carapace and plastron, +which Geoffroy depicts in Plate 4. It is a young specimen judging from the +small and isolated preneural; the seventh pair of pleurals is unusual in being +fused (no middorsal suture), and the neurals seem large in proportion to +the size of the pleurals. The anterior border of the carapace is described +as having tubercles. Geoffroy listed _Testudo membranacea_ and _Testudo +rostrata_ as synonyms of _carinatus_. Fitzinger (1835:127) listed _T. membranacea_, +_T. rostrata_ and _T. carinatus_ as synonyms of _Trionyx javanicus_ +(= _T. cartilagineus_), which was also described by Geoffroy (_op. cit._:15). +Duméril and Bibron (_op. cit._:478, 482) considered _carinatus_ to be the young +of _spinifer_ (_ferox_ as synonym). Gray (1844:48), however, referred _T. membranacea_ +and _T. rostrata_ to the synonymy of _T. javanicus_, but considered _T. +carinatus_ to be a synonym of _T. ferox_ (_op. cit._:50), an interpretation followed +by all subsequent authors. _Trionyx carinatus_ is questionably listed as a +synonym of _ferox_ by Stejneger (1944:27). Duméril and Bibron (_op. cit._:482) +wrote that the young type of _carinatus_ is in the museum at Paris. Dr. Jean +Guibé informs me in letter of September 24, 1959, that the type of Geoffroy's +_T. carinatus_ cannot be found in the Natural History Museum at Paris. For +the present, _T. carinatus_ is considered a _nomen dubium_. According to Stejneger +(1944:27), _Trionyx brongniarti_ Schweigger is a substitute name for +_T. carinatus_. + +I am unable to add anything to Stejneger's (_op. cit._:32) account of _Trionyx +harlani_; the mention of its occurrence in east Florida indicates that it is indistinguishable +from _Testudo ferox_ Schneider. + +_T. ferox_ was considered to be indistinguishable from Lesueur's _Trionyx +spiniferus_ (described in 1827), until Agassiz (1857:401) pointed out the +differences between the two species. However, Agassiz (_op. cit._:402, Pl. 6, Fig. +3) regarded juveniles of _T. spinifer asper_ as the young of _ferox_. Consequently, +the geographic range of _ferox_, as envisioned by Agassiz, extended from +Georgia and Florida west to Louisiana. Neill (1951:15) considered all +American forms conspecific. Crenshaw and Hopkins (1955) and Schwartz +(1956) demonstrated that _ferox_ is a distinct species. + +Fitzinger (1843:30) designated the species _ferox_ as the type species of +his genus _Platypeltis_ as follows: "Platypeltis. Fitz. Am[erica]. _Platypelt. +ferox_. Fitz. Typus." If populations of soft-shelled turtles that are referable +to _Testudo ferox_ Schneider are considered to comprise a distinct genus by +future workers, _Platypeltis_ Fitzinger, 1835, is available as a generic name with +_Testudo ferox_ Schneider, 1783, as the type species (by subsequent designation). + +_Trionyx ferox_ in the northern part of its range is sympatric with _T. spinifer +asper_. In the region of overlap, the two species are nearly always ecologically +isolated; _ferox_ inhabits lentic waters, whereas _T. s. asper_ is partial to lotic +waters (Crenshaw and Hopkins, _op. cit._:16). There is no evidence of intergradation +or hybridization. + +Many characters of _Trionyx ferox_ that are lacking in other North American +forms are shared with some Asiatic softshells, such as the large size, longitudinal +rows of tubercles that resemble ridges on the carapace, and the marginal +ridge. It is thought that, of the living softshells in North America, _ferox_ is +more closely allied to Old World forms of the genus than to _muticus_ or _spinifer_. + +Carr (1940:107) recorded _ferox_ from Okaloosa County, Florida, in the western +end of the panhandle, whereas Crenshaw and Hopkins (1955:16) list the +known westward extent of range as Leon and Wakulla counties. AMNH 6933 +from west of the Apalachicola drainage in Washington County, Florida, tends +to substantiate Carr's record, which is not included on the distribution map. + +_Specimens examined._--Total 144, as follows: FLORIDA: _Alachua_: UMMZ +64178, 100969; USNM 10545, 10704, "near" Gainesville; UMMZ 56599, Levy +Lake. _Brevard_: AMNH 12878, Canaveral. _Broward_: UMMZ 109441, Hugh +Taylor Birch State Park; USNM 109548, 22 mi. WNW, 6 mi. SSE Fort Lauderdale. +_Collier_: USNM 86828, Tamiami Trail, "near" Birdon. _Dade_: AMNH +50936, UMMZ 10183, 110981, Miami; USNM 84079, 86942, 15 mi. from (west) +Miami, Tamiami Trail; UMMZ 111371, 19 mi. W, 1.3 mi. S Miami; UI 28984, +35 mi. W. (Miami) Tamiami Trail; AMNH 69932-33, UMMZ 101582, 101584, +104024, 40-45 mi. W Miami, Tamiami Trail. _Glades_: UMMZ 100836, mouth of +Kissimmee River. _Hendry_: UMMZ 106302, 10.2 mi. SE Devil's Garden; +UMMZ 106303-04, 106321-22, 30 mi. S Clewiston, near Devil's Garden. +_Hernando_: TU 13624, 0.5 mi. S Citrus Co. line on US Hwy. 19. _Highland_: +AMNH 65537, 71618, Archbold Biol. Stat., Lake Placid; AMNH 65622, Hicoria. +_Hillsborough_: TU 13960, Hillsborough River, _ca._ 20 mi. NE Tampa; USNM +51184, Tampa; USNM 71156, Plant City. _Indian River_: USNM 55316, Vero +Beach; USNM 59318, Sebastian. _Lake_: UMMZ 36072, USNM 20189, 029210, +029339, 38123, Eustis; UMMZ 76754-56, Lake Griffin. _Lee_: UMMZ 102276, +14 mi. SE Punta Gorda. _Leon_: CNHM 33701, USNM 95767, Lake Iamonia; +USNM 103736, Silver Lake. _Marion_: AMNH 8294-95, UMMZ 95613 (4), +USNM 52476-83, 100902-04, Eureka; AMNH 63642, near Salt Springs. _Martin_: +TNHC 1292, 8.4 mi. N Port Mayaca. _Okeechobee_: AMNH 57379-84, Lake +Okeechobee; AMNH 5931-32, Kissimmee Prairie. _Orange_: USNM 51421, +56805, Orlando; KU 16528. _Osceola_: USNM 029448, 029450-64, 029467-68, +029470, 029474-75, Kissimmee. _Palm Beach_: UMMZ 54101, Palm Beach; +USNM 73199, Delray Beach. _Pinellas_: USNM 51417-20, St. Petersburg. _Polk_: +AMNH 25543, Lakeland; UMMZ 112380, 6.7 mi. S Lake Wales; USNM 60496, +60532, 60534, 61083-87, Auburndale. _Putnam_: USNM 4373, 7651, Palatka; +USNM 26035, ponds "near" Welaka. _Sarasota_: USNM 61352, Lake Myakka. +_Sumpter_: UMMZ 71791, Bushnell. _Volusia_: UMMZ 100673, Lake Helen. +_Washington_: AMNH 6933, Washington. _County unknown_: AMNH 4758; +USNM 8899, St. John's River: USNM 59727-28, Lake Okeechobee, "near" +mouth Taylor's Creek; USNM 84080. + +GEORGIA: _Baker_: SM 2083, USNM 029619, 38980-81, 70398, Mimsville. +_Berrien_: USNM 62217, Banks Mill Pond. _Charlton_: AMNH 69934, Okefinokee +Swamp, SW Billy's Island; UMMZ 90010, east edge Okefinokee Swamp; USNM +84603, Okefinokee Swamp, Chesser's Island. _Irwin_: USNM 56804. _Lowndes_: +UMMZ 67706, 10 mi. S Valdosta. _McIntosh_: USNM 19621, Darien. + +SOUTH CAROLINA: _Charleston_: USNM 9670, Charleston. + +NO DATA: AMNH 22750; USNM 71608-09. + +_Records in the literature._--FLORIDA: _Alachua_: 10 mi. ENE Gainesville +(Schwartz, 1956:18). _Brevard_: Merritt Island (Neill, 1958:6). _Broward_: +Fort Lauderdale (Schwartz, _op. cit._:19). _Charlotte_: (Carr, 1940:107). _Clay_: +Green Cove Springs (Brimley, 1910:18); St. John's River (Crenshaw and Hopkins, +1955:21); Doctor's Inlet (Schwartz, _op. cit._:18). _Collier_: Royal Palm +Hammock (Crenshaw and Hopkins, _op. cit._:20); 11.2 mi. E Monroe Station +(Schwartz, _op. cit._: 19). _Columbia_: (Carr, _loc. cit._). _Dade_: Paradise Key +(Schwartz, _loc. cit._); Homestead (eggs, Stejneger, 1944:43). _Duval_: 4-10 +mi. S Jacksonville (Deckert, 1918:31). _Glades_: _ca._ 8 mi. SW Okeechobee +State Park. _Lake_: Alexander Springs (Schwartz, _op. cit._:18). _Lee_: 18 mi. +S Fort Myers (Conant, 1930:63); 6 mi. SE Fort Myers (Hamilton, 1947:209). +_Levy_: Gulf Hammock (Schwartz, _loc. cit._); Brownson (Stejneger, _op. cit._:42). +_Monroe_ and _Okaloosa_ (Carr, _loc. cit._). _Okeechobee_: 6 mi. E Kissimmee River; +state hwy. 78 "near" Okeechobee-Glades co. line. _Palm Beach_: SW part of +Lake Okeechobee, near Clewiston; Milton Island Cove (Schwartz, _loc. cit._). +_Pasco_: mouth Pithlachascotee River (Neill, _op. cit._:26). _Pinellas_: Belleair +(Brimley, _loc. cit._); Seminole (Conant, _loc. cit._); 5 mi. E Clearwater (Schwartz, +_op. cit._:19); Gulf Port (Stejneger, _op. cit._:43). _Polk_: Lake Shipp, near +Winter Haven (Telford, 1952:185). _Sarasota_: 15 mi. E Sarasota (Conant, +_loc. cit._); Venice (Conant, _op. cit._:61). _Taylor_: "near" Foley. _Wakulla_: +"near" Crawfordville (Crenshaw and Hopkins, _op. cit._:15). + +GEORGIA: _Baker_: 5 mi. NW Newton, 5 mi. W Newton, 4 mi. N Newton. +_Ben Hill_: 6 mi. E Fitzgerald (Crenshaw and Hopkins, 1955:15). _Bulloch_: 14 +mi. SE Statesboro (Schwartz, 1956:19). _Decatur_: "near" Bainbridge (Crenshaw +and Hopkins, _loc. cit._). _Emanuel_: "near" Midville. _Evans_: 8 mi. NE +Manassas, Tattnall County. _Ware_: Laura Walker State Park (Schwartz, _loc. +cit._). _Wilcox_: 3 mi. SE Forest Glen (Crenshaw and Hopkins, _op. cit._:19). + +SOUTH CAROLINA: _Beaufort_: 7 mi. NE Gardens Corner (Schwartz, 1956:19). +_Chatham_: Savannah River at Savannah (Schwartz, _op. cit._:8-9). _Colleton_: 5 +mi. from Whitehall, Combahee River (Schwartz, _op. cit._:19). + + +=Trionyx spinifer= Lesueur + +Spiny Softshell + +_Range._--In Canada, southern Ontario and Quebec; in the United States, +northwestern Vermont and western New York south to northern Florida, east +to central Montana, eastern Wyoming and Colorado, and New Mexico; introduced +into the Colorado River system of California, Nevada, Arizona and New +Mexico; in México, the northern part of the states of Tamaulipas, Nuevo León, +Coahuila, and eastern Chihuahua (see map, Fig. 19). + +_Diagnosis._--Juvenal pattern uniform tan or brownish lacking markings, having +whitish dots or spots, or having well-defined, blackish ocelli or spots; surface +of carapace "sandpapery" in adult males; conical projections (in some subspecies) +along anterior edge of carapace in large females; contrasting pattern of +blackish marks on pale background (in some subspecies) on dorsal surface of +limbs of adult males. + +Opisthotic-exoccipital spur well-developed; epiplastral callosity, when present, +not covering entire surface. + +_Description._--Septal ridges present; external and proportional characteristics +variable (see accounts of subspecies); range in length of plastron (cm.) of ten +largest specimens of each sex (mean follows extremes), males, 13.8-16.0, 14.4; +females, 26.0-31.0, 28.0. + +[Illustration: FIG. 19. Geographic distribution of _Trionyx spinifer_. + +Guide to subspecies: + + 1. _T. s. spinifer_ + 2. _T. s. hartwegi_ + 3. _T. s. asper_ + 4. _T. s. pallidus_ + 5. _T. s. guadalupensis_ + 6. _T. s. emoryi_ +] + +Greatest width of skull usually at level of squamosal (74%); foramen +magnum rhomboidal; ventral surface of supraoccipital spine narrow +proximally, usually having medial ridge; opisthotic-exoccipital spur +well-developed (66%); distal part of opisthotic wing tapered, not +visible in dorsal view; lateral condyle of articular surface of +quadrate larger than medial articular surface, not tapered +posteriorly; maxillaries in contact above premaxillaries (88%); +usually a combination of seven neurals, seven pairs of pleurals and +contact of seventh pair of pleurals (83%); angle of epiplastron +approximately 90 degrees; callosities when present on epiplastron not +covering entire surface; hyo-hypoplastral suture usually present. + +_Comparisons._--_Trionyx spinifer_ can be distinguished from _T. +ferox_ and _T. muticus_ by the presence of any one of the characters +mentioned in the "Diagnosis." Both sexes and all sizes of _T. +spinifer_ resemble _ferox_ but differ from _muticus_ in having septal +ridges. Most individuals of _T. spinifer_ (except some large females) +resemble _muticus_ but differ from _ferox_ and large females of _ater_ +in having a pale outer rim that is separated from the ground color of +the carapace by a distinct (_spinifer_) or dusky (_muticus_) dark +line. Large females of the subspecies _spinifer_, _hartwegi_, _asper_ +and _pallidus_ may have enlarged conical projections along the +anterior edge of the carapace and, unless these projections are +considerably worn, are readily distinguished from large females of +_ferox_ (flattened, knoblike prominences), and _muticus_ and _ater_ +(smooth surface, no prominences). Large females of the subspecies +_guadalupensis_ and _emoryi_ resemble _muticus_ and _ater_, and to +some extent _ferox_, in having low, scarcely elevated prominences +along the anterior edge of the carapace. Some females of _emoryi_ +resemble _ferox_ in that the plastron extends farther forward than the +carapace. + +_T. spinifer_ is intermediate in size between _ferox_ (larger) and +_muticus_ (smaller); the maximum size of the plastron in adult males +is approximately 16.0 centimeters (14.0, _muticus_; 26.0, _ferox_), +and of females, 31.0 centimeters (21.5, _muticus_; 32.5, _ferox_). The +head for all subspecies of _spinifer_ is proportionately narrower than +in _ferox_ but wider than in _muticus_. + +In the skull, _spinifer_ more closely resembles _ferox_ than +_muticus_, but differs from both _ferox_ and _muticus_ in usually +having a well-developed opisthotic-exoccipital spur. Skulls of +_spinifer_ resemble those of _muticus_ but differ from those of +_ferox_ in being widest at the level of the squamosal. Skulls of +_spinifer_ resemble those of _ferox_ but differ from those of +_muticus_ in having the 1) ventral surface of the supraoccipital spine +narrow proximally, and usually having a medial ridge, 2) foramen +magnum rhomboidal, 3) distal part of opisthotic wing tapered, 4) +lateral condyle of articular surface of quadrate not tapered +posteriorly, and larger than medial articular surface, and 5) +maxillaries in contact above premaxillaries. _T. spinifer_ resembles +_ferox_ but differs from _muticus_ in having the epiplastron bent at +an approximate right angle. _T. spinifer_ differs from _ferox_ in +having an epiplastral callosity, and from _muticus_ in that the +callosity does not cover the entire surface of the epiplastron. The +hyo-hypoplastral suture is present more often in _spinifer_ and +_muticus_ than in _ferox_. + +_Remarks._--Gray (1869:221) proposed the generic name _Callinia_ as a +new name for _Aspidonectes_ as understood by Agassiz (1857:403). Gray +referred _Trionyx spiciferus_ (= _spiniferus_) Lesueur to _Callinia_. +Stejneger (1907:514) designated _Trionyx spiniferus_ Lesueur as the +type species of _Callinia_. If _Trionyx spiniferus_ Lesueur is +considered to be generically distinct from other soft-shelled turtles, +_Callinia_ Gray, 1869, is available as a generic name with _Trionyx +spiniferus_ Lesueur, 1827, as the type species by subsequent +designation. + +_Geographic variation._--_T. spinifer_ is the most variable and +widespread species of the genus in North America. Size of ocelli on the +carapace decreases from east to west on turtles inhabiting waterways of +the Upper Mississippi River drainage. The most impressive gradient, +geographically oriented from western Louisiana to southwestern Texas is +seen in each of several features: decrease in size of tubercles on the +anterior edge of the carapace, reduction in contrast of pattern on the +dorsal surface of limbs and side of head, change in pattern on the +dorsal surface of the snout, and increase in the size of white spots on +the carapace. But the gradient in size of white spots is reversed in _T. +s. emoryi_, which has small white spots on the carapace. Some of the +characters at the western terminus of this geographical gradient are +shared with _T. ater_ and _muticus_. Those subspecies comprising the +_emoryi_ group also show proportional characters that correspond closely +with those of _T. ferox_. + +On the basis of tuberculation and pattern on carapace, side of head, +dorsal surface of limbs and snout, _Trionyx spinifer_ may be divided +into six subspecies. + + +=Trionyx spinifer spinifer= Lesueur + +Eastern Spiny Softshell + +Plates 33, 34, and 52 + + _Trionyx spiniferus_ Lesueur, Mém. Mus. Hist. Nat. Paris, 15:258, + pl. 6, December, 1827. + + _T[rionyx] s[pinifer] spinifer_ Schwartz, Charleston Mus. Leaflet, + No. 26:11, May, 1956. + + _Trionyx ocellatus_ Lesueur, Mém. Mus. Hist. Nat. Paris, 15:261, + December, 1827. + + _Apalone hudsonica_ Rafinesque, Atlan. Jour., Friend Knowledge, + Philadelphia, 1(No. 2, Art. 12):64, Summer, 1832. + + _Trionyx annulifer_ Wied-Neuwied, Riese Nord-Amerika, 1(pt. 3):140, + 1838. + + _Tyrse argus_ Gray, Cat. Tort. Croc. Amphis. Brit. Mus., p. 48, + 1844. + + _Aspidonectes nuchalis_ Agassiz, Contr. Nat. Hist. United States, + 1(pt. 2):406, 1857. + + _?G[ymnopus] olivaceus_ Wied-Neuwied, Nova Acta Acad. + Leopold.-Carol., 32:55, pl. 5, 1865. + +_Type._--Lectotype, Museum d'Histoire Naturelle, Paris, No. 8808; +large stuffed female obtained by C. A. Lesueur from the Wabash River, +New Harmony, Posey County, Indiana (Pl. 52). + +_Range._--Northeastern United States and extreme southeastern Canada +in tributaries flowing into the Mississippi River from the east, and +the St. Lawrence River drainage; extreme southern Quebec and Ontario, +Canada, east through southern Great Lakes region to Wisconsin, and +south through New York, western Pennsylvania and Illinois to Tennessee +and western Virginia (see map, Fig. 19). + +_Diagnosis._--Juvenal pattern of large, thick-bordered black ocelli, +often 9-10 millimeters in diameter in center of carapace on adult +males, and 2-3 millimeters in diameter on hatchlings (mean OD/PL, +Michigan, .066); only one dark marginal line separating pale rim of +carapace from dorsal ground color. + +_Description._--Plastral length of smallest hatchling, 2.7 centimeters +(UMMZ 89950, INHS 3143); of largest male, 14.5 centimeters (UMMZ +72512); of largest female, 31.0 centimeters (UMMZ 40866). + +Carapace olive, having large ocelli in center but smaller ocelli or +spots at sides; ocelli often interrupted; pale rim of carapace not +four or five times wider posteriorly than laterally, separated from +darker ground color of carapace by one dark marginal line; large +females often having remnants of ocelli at sides of carapace on +mottled and blotched background; pattern on snout of pale, +dark-bordered stripes that unite forming acute angle in front of eyes; +well-defined dark markings in subocular and postlabial region; pattern +contrasting with ground color on side of head; postlabial stripe +interrupted, diffuse; pale postocular stripe having blackish borders +interrupted, not uniting with postlabial stripe; dorsal surface of +soft parts of body having contrasting pattern, largest blackish marks +on hind limbs; elongate tail of adult males having pale dorsolateral +bands with well-defined lower blackish borders; underparts whitish, +often having blackish marks, except in center of plastral area; dark +marks on webbing of limbs, palms and soles; dark streaks often +coincident with digits; small conical tubercles on anterior edge of +carapace on adult males; conical or equilateral tubercles on anterior +edge of carapace of large females; accessory knoblike tubercles in +nuchal region and in middle of carapace posteriorly on large females. + +Ontogenetic variation in PL/HW, mean PL/HW of specimens having +plastral lengths 7.0 centimeters or less, 4.09, and exceeding 7.0 +centimeters, 5.50; ontogenetic variation in CL/CW, mean CL/CW of +specimens having plastral lengths 8.5 centimeters or less, 1.12, and +exceeding 8.5 centimeters, 1.21; mean CL/PCW, 2.02; mean HW/SL, 1.30 +(including subspecies _hartwegi_); mean CL/PL, 1.39. + +_Variation._--Variant individuals include: UMMZ 72512, an adult male, +having some ocelli seven millimeters in diameter that are almost solid +spots; UMMZ 89659 having postocular and postlabial stripes connected +on right side of head; UMMZ 95615, 52948, 54402 having inner dark +borders of pale stripes on snout represented by short dashes and dots +(a ragged line connecting anterior margins of orbits on 54402); UMMZ +52948, 89659 having interrupted, black marginal lines on carapace with +ends of some segments oriented inward and overlapping portion of +adjacent segments; UMMZ 81699, female having plastral length of 19.0 +centimeters, lacking conspicuous tubercles on anterior edge of +carapace; UI 2403, CNHM 92204 having extensive dark mottling and +marbling on throat and neck, undersurface of limbs and posterior +portion of carapace. + +_Comparisons._--_T. s. spinifer_ can be distinguished from all other +subspecies of _T. spinifer_ by the presence of large black ocelli +(diameter 9-10 mm. on adult males, 2-3 mm. on hatchlings) in +combination with only one dark marginal line. _T. s. spinifer_ +resembles _asper_ in having ocelli or dots on the carapace but differs +from _asper_ in having only one dark marginal line and larger ocelli. +_T. s. spinifer_ differs from _hartwegi_ only in the large size of the +ocelli. _T. s. spinifer_ resembles _hartwegi_ and _asper_ but differs +from _pallidus_, _guadalupensis_ and _emoryi_ in having blackish spots +and ocelli on the carapace and lacking whitish dots. _T. s. spinifer_ +resembles _hartwegi_, _asper_, and _pallidus_ and differs from +_guadalupensis_ and _emoryi_ in having conical or knoblike tubercles +on the anterior edge of the carapace on large females. + +_T. s. spinifer_ differs from the subspecies _asper_, _guadalupensis_ +and _emoryi_ in having a relatively narrower head, and from _emoryi_ +in having a relatively wider carapace. _T. s. spinifer_ resembles +_hartwegi_ and _asper_ but differs from the other subspecies in having +the carapace widest at a plane approximately one-half way back on the +carapace. The subspecies _spinifer_ and _hartwegi_ have longer snouts +than _pallidus_, _guadalupensis_, and _emoryi_. _T. s. spinifer_ +differs from _asper_ but resembles all the other subspecies in having +a relatively longer plastron. + +_Remarks._--Lesueur's description of _Trionyx spiniferus_ +(1827:258-261, Pl. 6) seems to be based mostly, if not entirely, on a +large female (length of carapace, 13 inches), which was "Le plus grand +des individus observes ..." (_op. cit._:258); an accompanying +illustration depicting the dorsal surface of the bony carapace is +unusual in lacking neurals (Pl. 6, E). Duméril and Bibron (1835:481) +mentioned eight or nine additional specimens that Lesueur sent to the +Museum of Natural History in Paris. Dr. Jean Guibé informed me under +letter dated September 24, 1959, that a larger stuffed female, bearing +catalog number 8808 is regarded as the holotype, and that there are +seven additional specimens (1949, 4143, 8807, 8809-12) in the museum +at Paris. All turtles were obtained by Lesueur from the Wabash River. +To my knowledge no specimen that was available to Lesueur has been +specifically designated as a type. Because the description seems to be +based on one specimen, undoubtedly No. 8808, this specimen has been +regarded as the holotype. However, Lesueur referred to several +specimens and did not mention a type in the original description; +consequently I prefer to regard No. 8808 as a lectotype. + +Lesueur also described _Trionyx ocellatus_ (_op. cit._:261-263) as a +variety of _T. spiniferus_ having ocelli, or parts thereof, on the +carapace and mentioned three specimens. The total number of specimens +that were available to Lesueur is unknown. One young alcoholic +specimen having ocelli is in the British Museum (Natural History) +(Gray, 1855:69). The same letter from Dr. Guibé stated that a specimen +in the Museum of Natural History, Paris, No. 6957, having a carapace +17 centimeters in length, conforms to the characters of _ocellatus_ as +mentioned by Lesueur, and was obtained from the Wabash River by +Lesueur. Two of the specimens mentioned by Lesueur (_loc. cit._) are +stated to be females. No. 6957 is an adult male and clearly shows the +juvenal pattern; it is regarded as the lectotype of _T. ocellatus_ +Lesueur, a name-combination, which is a synonym, based on a secondary +sexual difference in pattern. + +Rafinesque (1832:64) described a soft-shelled turtle from "the River +Hudson between the falls of Hadley, Glen and Baker, and further up to +the source" as _Apalone hudsonica_. The most outstanding +characteristic was the presence of five claws on the digits of each +limb. Rafinesque's recording of this characteristic was perhaps +influenced by the illustration of a softshell in Bartram's _Travels_ +that showed each limb with five, clawed digits. Perhaps this was the +basis for Boulenger (1889:245, footnote) regarding _Apalone_ as +"mythical." The large, yellowish, black-bordered spots, one behind and +one in front of the eye presumably represent segments of the +postocular stripe and the stripe on the snout; Rafinesque described +the carapace as "entire ... the margin is yellowish unspotted, then +comes a circular black line ..." and having "many round spots +occulated and clouded by having a brown margin, with grey dots +within." Except for five claws, the description is applicable to a +softshell and referable to _T. s. spinifer_. To my knowledge, the only +other records of the occurrence of soft-shelled turtles in the Hudson +river drainage are those of Eights (_in_ Bishop, 1923:120, Mohawk +River at Cohoes), and DeKay (1842:7, Mohawk River and Hudson River +near Albany); presumably these records are the basis for the comments +of Holbrook (_in_ Bishop, _loc. cit._), and symbolized as an isolated +locality by Conant (1958:318, map 35). The type locality of _Apalone +hudsonica_ is herein restricted to the Hudson River, near Baker's +Falls, Saratoga County, New York. + +Gray (1844:48) proposed the name _Tyrse argus_ for a specimen reported +to have come from Sierra Leone, West Africa; later (1855:68), he +referred the species to the genus _Trionyx_. After comparison with a +specimen of _T. spiniferus_ Lesueur, Gray (1864:89) was "doubtful +whether there must not have been some confusion about the habitat of +the specimen [which formed the basis of the description of _Tyrse +argus_], and whether it is not more probably a North American +species." The same author (1869:222; 1870:109) listed _Tyrse argus_ as +a synonym of _Callinia spinifera_ (= _Trionyx spiniferus_ Lesueur). + +Agassiz (_op. cit._:406-07) described _Aspidonectes nuchalis_ on the +basis of three adults from the Cumberland River and a number of young +from the headwaters of the Tennessee River. Boulenger (1889:245, +footnote 2) suggested that the status of _A. nuchalis_ required +further investigation. The species was not generally recognized after +the turn of the century. Barbour and Loveridge (1929:226) listed MCZ +1908 (one of the juveniles) and 1623-25 as cotypes. Stejneger +(1944:52) showed that _nuchalis_ was not distinguishable from _T. s. +spinifer_, and (_op. cit._:49) listed MCZ 1623-25 as cotypes. Schmidt +(1953:110) restricted the type locality to the Cumberland River, near +Nashville, Tennessee. + +Agassiz (_loc. cit._) mentioned that _nuchalis_ "differs strikingly +from Asp. spinifer in the much more elongated form of the male, and in +the great development of the marginal spines and of the tubercles upon +the carapace, ... But the most prominent specific character consists +in the marked depressions on either side of the blunt median keel, and +also in the triangular dilation of that keel behind the front margin +of the carapace." These characters seem to be of no taxonomic worth. I +have seen three syntypes (MCZ 1623-25) that undoubtedly correspond to +the three adult specimens mentioned by Agassiz. All are females, +measuring 19.5, 22.0, and 19.0 centimeters, respectively, in plastral +length, and lack a contrasting mottled pattern on the carapace; the +juvenal pattern is obscured, except for blackish spots at the edge of +the carapace on MCZ 1625, and parts of an ocellus on MCZ 1624. The +dorsal surfaces of the limbs are boldly marked. MCZ 1623, showing the +diagnostic feature mentioned by Agassiz, is photographed by Stejneger +(_op. cit._:Pls. 14, 15), and may be regarded as the lectotype of +_Aspidonectes nuchalis_ Agassiz. MCZ 1908 is one of the young syntypes +mentioned by Agassiz, and is referable to _spinifer_. The juvenal +pattern consists of spots and ocelli; the plastron measures 3.1 +centimeters in length, and the carapace 4.2 centimeters. + +Wied-Neuwied (1865:55-57, Pl. 5) described the species _?G_[_ymnopus_] +_olivaceus_, but was uncertain whether his interpretation was based on +a species, a variety or a secondary sexual difference. Wied-Neuwied +mentioned that Lesueur had already named this soft-shelled turtle as +_Trionyx ocellatus_, and agreed with Lesueur that those turtles having +occulated spots on the carapace were distinguishable from _T. +spiniferus_ and _T. muticus_. But because Duméril and Bibron in their +_Erpétologie Général_ failed to recognize _T. ocellatus_, Wied-Neuwied +felt obliged to bring it to the attention of his American colleagues +and he renamed it. Wied-Neuwied also stated, in the context of a +synonym, "Beschreibung einer Reise in Nord-America Bd. I., pag. 140." +This comment presumably refers to his earlier description of _T. +annulifer_ (1838:140); seemingly Wied-Neuwied considered _T. +annulifer_ and _G. olivacea_ as conspecific, although there is no +mention of _annulifer_ in the text proper. Stejneger (_op. cit._:49) +designated the type locality of _T. annulifer_ as the Ohio River at +Pittsburgh, Pennsylvania, and of _Gymnopus olivacea_ as New Harmony, +Wabash River, Illinois (_lapsus_ for Indiana). + +_Trionyx spiniferus_ was questionably considered distinct from _T. +ferox_ by Lesueur who listed "Testudo ferox Gm. Tortue de Pennant?" +and "Trionyx georgicus Geoffr.?" as synonyms. Subsequently, most +authors considered _T. spiniferus_ synonymous with _T. ferox_ until +Agassiz (1857) pointed out differences between the two species. + +The average size of the ocelli on the carapace of the subspecies +_spinifer_ decreases westward toward the Mississippi River; ocelli of +different sizes occur on different individuals from the same state and +presumably from the same population. For example, INHS 2281, plastron +9.9 centimeters in length, from Effingham County, Illinois, has some +ocelli eight millimeters in diameter, whereas a larger male from the +same locality, UI 1322, plastron 11.6 centimeters in length, has the +largest ocelli only five millimeters in diameter. For convenience, all +softshells having locality data from states east of the Mississippi +River are referred to _spinifer_, recognizing that intergradation +occurs with _hartwegi_ over a broad area paralleling the Mississippi +River. The type locality of _spinifer_ is in an area where most +turtles do not have the larger ocelli (diameter of seven to ten mm. on +adult males); however, some individuals from the Wabash River (UMMZ +63523, adult male, plastron 11.5 cm. in length, ocelli diameter seven +mm.) agree with more "typical" _spinifer_ to the east. Intergradation +with _asper_ possibly occurs in that part of the Tennessee River in +eastern Tennessee as exemplified by UMMZ 59198. + +Published reports indicate that _T. s. spinifer_ is not abundant in +some of the northeasterly parts of its geographic range. Adams and +Clark (1958:10) wrote that few softshells at Long Point on the +Canadian side of Lake Erie are "ever collected and the area's game +keepers report ... (none) ... seen in recent years. They also tell of +recurrent severe stormy winters in which the muddy bottom of the +marshland was repeatedly churned up and frozen. Such climatic +conditions could easily destroy a large part of the _Trionyx_ +population overwintering in the mud bottom." Wright (1919:8) reported +that softshells are "rarely seen" in bays on the New York side of Lake +Ontario, and Babcock (1938:53) wrote that _spinifer_ "is not common in +Lake Champlain." + +_T. s. spinifer_ probably extended its geographic range into the +Hudson River drainage of New York _via_ the Erie Canal (connected +Buffalo and Albany) after its completion in the early 1800's (DeKay, +1842:7). Now, the New York Barge Canal (essentially the Erie Canal, +but with minor changes in course and the addition of several spurs) +provides an avenue for dispersal of _spinifer_ to the Hudson River +drainage, Lake Ontario and intervening waterways in New York (Mertens, +1928:199). Netting (1944:86-87), however, suggested that _spinifer_ +occupied Lake Champlain, the Finger Lakes, Mohawk River and upper +Hudson in the late stages of the formation of the Great Lakes. + +A publication not seen by me is that of Mansueti and Wallace (1960). +Its title suggests that _Trionyx_ occurs in Maryland. + +The unsuccessful introduction of _T. s. spinifer_ in the Delaware +drainage in New Jersey has been discussed by Fowler (1907:213), who +wrote that they were found as early as the late 1860's and were +introduced when young presumably to stock aquaria. Records of +occurrence include Cooper's Creek, Camden County (Stone, 1906:168); +Woodbury, Gloucester County (Cope, 1894:889); and Paulins Kill at +Hainesburg, Warren County (Johnson, 1894:889). + +Surface (1908:122) believed that soft-shelled turtles "have doubtless +been introduced into the eastern part of Pennsylvania through the +canal from the Western and Central part of New York," and Roddy (_in_ +Neill, 1951:21) suggested that the species may be found in the +Susquehanna River. Babcock (1919:420) mentioned a young specimen of +_spinifer_ in the collection of the Boston Society of Natural History +that was obtained "in White River, Vermont," a tributary of the +Connecticut River of the Atlantic Coast drainage; seemingly this +record has not been accepted and the species is not established. To my +knowledge, populations of _T. s. spinifer_ do not occur in rivers of +the Atlantic Coast drainage, except probably the Hudson-Mohawk +drainage. + +Stockwell (1878:401) wrote that _spinifer_ was found "as high as +Athabasca." Presumably Stockwell referred to Lake Athabaska in +northern Alberta and Saskatchewan, Canada, a region where soft-shelled +turtles are unknown; see also the comments by Stejneger (1944:52). + +_Specimens examined._--Total 250 as follows: ALABAMA: _Morgan_: UMMZ +99578, "near" Decatur. + +ILLINOIS: _Adams_: INHS 2150, Quincy. _Bond_: INHS 8345, Greenville. +_Carroll_: CNHM 42116, Ordnance School Proving Ground. _Cass_: INHS +2151, Beardstown. _Champaign_: INHS 2273, 2311, 2413, 3142, "near" +Seymour; INHS 4229, Champaign; INHS 6163, Sidney. _Christian_: INHS +1560, Pana. _Coles_: INHS 1968-69, 2 mi. W Charleston. _Cumberland_: +INHS 2282, Greenup. _De Witt_: INHS 7674, Farmer City. _Effingham_: UI +1322, 2281, 19365, "near" Effingham. _Fulton_: INHS 5531, 2 mi. NE +Bluff City, Schyler County; UI 23449, Liverpool; UI 24611, Spoon +River, 18 mi. NW Canton. _Hancock_: USNM 53522, 59277, "near" +Hamilton. _Iroquois_: INHS 6869-70, 2.5 mi. N Crescent City. +_Jackson_: TU 1369 (12), Elkville. _Kane_: CNHM 42400, Aurora. +_Kankakee_: CNHM 324, Momence. _Kendall_: UI 2411, Plano. _Logan_: +INHS 7171-72, 6 mi. N Lincoln. _Madison_: USNM 60571. _Macoupin_: UI +2401-02, Beaver Dam Lake. _Mason_: CNHM 346, 470, INHS 1122, 1559, +5756-58, UI 42, 2404, Havana, Lake Chautauqua. _Mercer_: CNHM 3220, +New Boston. _Morgan_: CNHM 2067 (2), 3290, 3303-04, 3306, INHS 2152, +2154, 5132-37, USNM 54747, Meredosia. _Moultrie_: INHS 8989, 2 mi. NW +Lovington. _Peoria_: UI 2406-10, Peoria. _Pope_: INHS 5505, Lake +Glendale. _Putnam_: UMMZ 81604-14, 5 mi. N Henry, Marshall County. +_Schuyler_: UI 2405, "near" Ripley, Brown County. _Scott_: INHS 2149, +2153, Naples. _Union_: CNHM 18623, 6 mi. SW Jonesboro. _Vermilion_: +INHS 3142, Muncie; INHS (1 untagged); UI 1970, 3209, Danville; UI +2403, 1.5 mi. E Oakwood; UI 16265, Kickapoo State Park. _Wabash_: USNM +12061, Mt. Carmel. _Winnebago_: INHS 7185, Kishwaukee Forest Preserve; +INHS 7294, 1/2 mi. S Shirland. _County unknown_: USNM 7661. + +INDIANA: _Bartholomew_: UMMZ 61060, 10 mi. W Columbus. _Carroll_: USNM +42905-06, Burlington. _Clark_: UMMZ 110599, 14-mile Creek, 3 mi. NW +Charleston. _Decatur_: UMMZ 55416, 3 mi. S Westport. _Elkhart_: UMMZ +105598, Elkhart River, south of Goshen. _Gibson_: UMMZ 89744, Foot's +Pond. _Johnson_: UMMZ 108062, 2 mi. S Trafalgar. _Knox_: USNM 22711, +Vincennes. _Kosciusko_: AMNH 8379, UMMZ 84287 (5), Winona Lake; UMMZ +110235, Wawasee Lake. _Lake_: CNHM 11019, 11021-24, Crown Point. +_Marion_: UMMZ 103393, Ravenswood; UMMZ 110236, 1 mi. N Lawrence. +_Marshall_: CNHM 39299; USNM 33495, Yellow River north of Burr Oak; +USNM 33496-501, 35404, 42583-84, Lake Maxinkuckee. _Wells_: UMMZ +63523, Wabash River, Bluffton. _County unknown_ (Lagrange or +Marshall): USNM 50670, Twin Lakes. + +KENTUCKY: _Casey_: UMMZ 112252, trib. of Green River, south of +Yosemite. _Green_: UMMZ 116718, Little Barren River, 1.5 mi. E Monroe, +Hart County. _Rockcastle_: UMMZ 98767, Rockcastle River, 5 mi. above +Livingston. + +MICHIGAN: _Allegan_: UMMZ 42112, Kalamazoo River. _Barry_: UMMZ 53874, +Thornapple River, 3 mi. NW Hastings. _Bay_: UMMZ 74670. _Branch_: UMMZ +95615, 1 mi. S Kinderhook; UMMZ 70748, Hog Creek. _Calhoun_: UMMZ +89950 (3); UMMZ 79133, near Battle Creek. _Cass_: UMMZ 40866-67, +53005, Diamond Lake; UMMZ 40868, 52948, Long Lake. _Jackson_: UMMZ +72494. _Kalamazoo_: UMMZ 42130, 80534, Kalamazoo; UMMZ 90506, Gull +Lake; UMMZ 92599, Kellogg Bird Sanctuary. _Lenawee_: UMMZ 72457, +Devil's Lake; UMMZ 74662, Wolf Lake Park. _Livingston_: UMMZ 54401, +76190, Portage Lake. _Monroe_: UMMZ 44604-06, USNM 51213, "near" +Monroe. _Newaygo_: UMMZ 63469. _Oakland_: UMMZ 64363, Hay's Creek; +UMMZ 96539, Clinton River. _Ottawa_: UMMZ 81699. _St. Joseph_: UMMZ +38876, 38889, "near" White Pigeon; UMMZ 96537, Corey Lake. _Van +Buren_: UMMZ 90003, Wolf River, west of Kalamazoo, Kalamazoo County. +_Washtenaw_: SM 2035, 2038, 2105, UMMZ 39847, 96538, "near" Ann Arbor; +UMMZ 35765, 35769, 74518 (2), Portage Lake; UMMZ 54402-03, Little +Lake; UMMZ 89659, Huron River, Dexter; UMMZ 110583-85. _County +unknown_ (Washtenaw or Livingston): UMMZ 54400, Huron River near +Portage Lake. + +MISSISSIPPI: _Adams_: MCZ 46615, UMMZ 76446, "near" Natchez; MCZ +46621, 46633, USNM 01084, 01086, Washington. _Coahoma_: AMNH 5289, +5285-86, Moon Lake. _Lafayette_: MCZ 37173, Oxford; USNM 7650, +Abbeville? (reported from Abbeville, South Carolina by Pickens, +1927:113; see discussion by Stejneger, 1944:50, and my comments on +page 509 beyond). _LeFlore_: USNM 73668-69, Greenwood. _Madison_: USNM +95192, Big Black River. _Washington_: USNM 115980, Deer Creek. +_Yazoo_: UMMZ 86669, Panther Creek west of Yazoo City; UMMZ 83304, +Yazoo City. + +NEW YORK: _Monroe_: CNHM 92001-02, Genesee River, Rochester. _Wayne_: +AMNH 69931, CNHM 92004, Sodus Bay. + +OHIO: _Athens_: UMMZ 111793, east branch Shade Creek. _Franklin_: USNM +26290. _Lucas_: USNM 51214, Toledo. _Pike_: UMMZ 99309, Morgan's Fork, +Sunfish Creek. _Warren_: AMNH 4763, Little Miami River, 3 mi. below +Morrow. _County unknown_: USNM 21128-29, Cuyahoga River. + +TENNESSEE: _Benton_: UMMZ 113036, Eagle Creek, 1/2 mi. E Holliday. +_Bradley_: UMMZ 59197, west branch of Chestnee Creek, 7 mi. E +Cleveland. _Claiborne_: USNM 86677, 5 mi. SE Cumberland Gap, Powell +River. _Davidson_: MCZ 1623-25, Cumberland River near Nashville +(restricted locality); USNM 7165-67, Nashville. _Decatur_: KU 3000, +Perryville. _Hamilton_: USNM 131861, Chattanooga. _Monroe_: TU 16058, +Little Tennessee River, 10 mi. N Madisonville. _Obion_: UMMZ 53199, +USNM 102911, Reelfoot Lake. _Overton_: UMMZ 69561 (2), Wirmingham. +_Sevier_: TU 16132, UMMZ 86735, USNM 86681-82, near Sevierville; UMMZ +86734, Walden Creek "near" Gatlinburg. _County unknown_: MCZ 1908, +headwaters of Tennessee River. + +VIRGINIA: _Smythe_: USNM 101386, Holston River, Seven Mile Ford. + +WEST VIRGINIA: _McDowell_: USNM 33767, Dry Fork, Perryville (county +questionable, perhaps Randolph County). + +WISCONSIN: _Chippewa_: CNHM 8223, Lake Wissota, mouth of Yellow River, +Anson Twp. _Polk_: UMMZ 72511-12, St. Croix River "near" Never's Dam. +_County unknown_: CNHM 15971, Eau Claire River. + +_Records in the literature._--ONTARIO: _Carleton_: Ottawa +(questionable record). _Essex_: Point Pelee. _Haldimand_: Dunville. +_Kent_: Lake St. Clair. _Norfolk_: Long Point. _Oxford_: Beachville. +_Wentworth_: Hamilton Bay (Logier and Toner, 1955:51). + +QUEBEC: _Iberville_: Richelieu River at Iberville (Logier and Toner, +1955:51). + +ALABAMA: _Lawrence_: Courtland (Stejneger, 1944:53). + +ILLINOIS: _Boone_: Belvidere. _Bureau_: Bureau. _Cass_: Chandlerville. +_Clay_: Louisville (Cahn, 1937:189). _Cook_: Lake Michigan (Kennicott +_in_ Stejneger, 1944:44); Evanston (Necker, 1939:10); Chicago (Schmidt +and Necker, 1935:76). _Crawford_: Robinson. _Douglas_: northern part +of county (P. W. Smith, 1947:39). _Fayette_: Vandalia. _Fulton_: +Ellisville (Cahn, _loc. cit._). _Grundy_: Morris (Stille and Edgren, +1948:201). _Jackson_: Jacob (Cagle, 1942:158). _Jersey_: Grafton +(Cahn, _loc. cit._). _Kane_: Batavia; Dundee Game Farm (Stille and +Edgren, _loc. cit._). _Kankakee_: Kankakee River near Altort (Necker, +_loc. cit._). _Lake_: Fox Lake. _LaSalle_: Streator (Cahn, _loc. +cit._). _Lawrence_: (Hahn _in_ Stejneger, 1944:44). _Lee_: symbol on +map (Cahn, _loc. cit._). _McHenry_: McHenry (Stille and Edgren, _loc. +cit._). _Macon_: Decatur. _Macoupin_: Carlinville (Cahn, _loc. cit._). +_Ogle_: Oregon (Garman _in_ Cahn, _loc. cit._). _Randolph_: Chester, +Reily Lake. _Rock Island_: Barstow, Hillsdale, Rock Island (Cahn, +_loc. cit._). _Saline_: Horseshoe Lake (Stein, 1954:312). +_Stephenson_: Freeport (Cahn, _loc. cit._). _Union_: Bluff Lake +(Garman _in_ Cahn, _loc. cit._). _Whiteside_: Sterling, symbol on map +(Cahn, _loc. cit._). _Williamson_: Marion (Cagle, 1942:158). +_Winnebago_: Rockton; symbol in western part of county (Cahn, _loc. +cit._). _County unknown_: Fox River (Yarrow, 1882:29). + +INDIANA: _Brown_: 1 mi. below Helmsburg (Myers, 1927:339). _Clay_: Eel +River (Kirsch _in_ Stejneger, 1944:45). _Franklin_: (Hughes _in_ +Stejneger, _loc. cit._). _Jasper_: Jasper-Pulaski Game Preserve +(Swanson, 1939:690). _Jefferson_: Madison (Myers, _loc. cit._). +_Marion_: Irvington (Stejneger, _op. cit._:55). _Marshall_: 2 mi. NW +Culver (KKA). _Monroe_: Bloomington (McLain _in_ Stejneger, _op. +cit._:45). _Newton_: Lake Village (Stille and Edgren, _loc. cit._). +_Posey_: Wabash River at New Harmony (Lesueur, 1827:257). _Starke_: +Grant (Stille and Edgren, _loc. cit._). _Steuben_: Fish Creek "near" +Hamilton (Stejneger, _op. cit._:53). _County unknown_ (Knox or +Starke): USNM 72387, Knox (Stejneger, _op. cit._:55); "White Water +valley," east-central part of state (Butler, 1894:224). USNM 8359 (= +_Trionyx spinifer asper_) has been erroneously recorded from Madison, +Indiana, by Yarrow (1882:29) and Hay (1892:145); see discussion by +Cahn (1937:200) and Stejneger, (_op. cit._:73, 75). + +KENTUCKY: _Edmonson_: Green River, Mammoth Cave National Park +(Hibbard, 1936:281). _Fleming_: Fox Creek (Welter and Carr, 1939:130). +_Jefferson_: (Funkhouser, 1925:71). _Morgan_: (Stejneger, 1944:54). +_County unknown_: Ohio and Pond rivers (Funkhouser, _loc. cit._). + +MICHIGAN: _Berrien_: mouth of St. Joseph River at St. Joseph (Lagler, +1943:303). _Eaton_: Brookfield; Olivet (Clark _in_ Ruthven, Thompson +and Thompson, 1912:133). _Genesee_: (Miles _in_ Ruthven, Thompson and +Thompson, _loc. cit._). _Iosco_: (Lagler, 1943:283, symbol on map). +_Kent_: (Lagler, _loc. cit._). _Montcalm_: (Clark _in_ Ruthven, +Thompson and Thompson, _loc. cit._). _Muskegon_: Muskegon River "near" +Muskegon (Lagler, _op. cit._:303). _Van Buren_: Reynolds Lake, 2.5 mi. +E Lawrence (Edgren, 1942:180). + +MISSISSIPPI: _De Soto_: Lake Cormorant (Stejneger, 1944:55). _Holmes_: +Thornton (Cook, 1946:185). _Humphreys_: Belzoni (Stejneger, _loc. +cit._). _Sunflower_: _Warren_: Vicksburg, Eagle Lake (Cook, _loc. +cit._). _Washington_: Lake Washington (Smith and List, 1955:125); +Greenville (Stejneger, _loc. cit._). + +NEW YORK: _Albany_: Hudson River at Albany (DeKay, 1842:7); Mohawk +River at Cohoes (Eights _in_ Bishop, 1923:120). _Cattaraugus_: +Allegheny River and Red House Lake in Allegheny State Park (Eaton, +1945:115). _Chautauqua_: Lake Chautauqua (DeKay, _loc. cit._). +_Monroe_: Braddocks Bay and Long Pond on Lake Ontario (Wright, +1919:8). _Saratoga_: Hudson River near Baker's Falls (restricted +locality, Rafinesque, 1832:64). _County unknown_: Lake Cayuga; Mohawk +River (DeKay, _loc. cit._). + +OHIO (Conant, 1951:158-59, 264, except records from Allen, Geauga and +Noble counties): _Allen_: Sugar Creek, 6 mi. N Lima (Adler and Dennis, +1960:27). _Ashland_: Long Lake, Lake Twp.; Black Fork, Sec. 27, Green +Twp. _Athens_: Hocking River "near" Athens; "near" Fisher, Alexander +Twp. _Auglaize_: Pusheta Creek, west of Wapakoneta. _Brown_: White Oak +Creek, 1 mi. N Higginsport. _Butler_: Oxford. _Champaign_: Mad River, +4 mi. SW Urbana. _Coshocton_: Walhouding River, below dam. _Defiance_: +Auglaize River, Shawnee Scout Camp, Defiance Twp. _Erie_: Huron; +Sandusky. _Fairfield_: Buckeye Lake. _Franklin_: Alum Creek, +Westerville; Columbus. _Geauga_: Chardon Twp. (Wood, 1959:8). +_Greene_: Huffman Dam. _Hamilton_: Harrison; mouth of Miami River. +_Hardin_: "near" Hepburn. _Henry_: Maumee River, east of Napoleon; +Maumee River "near" Texas; Maumee River, 3 mi. W Texas. _Highland_: +Little Brush Creek, 2 mi. N Sinking Spring. _Huron_: Huron River +"near" Monroeville. _Jackson_: Canter's Cove, Jackson Twp.; Jackson +Lake. _Knox_: Brinkhaven. _Lake_: east branch Chagrin River, Kirtland; +Grand River, 4 mi. E Painesville. _Lawrence_: Pine Creek, Elizabeth +Twp. _Logan_: Miami River, "near" Indian Lake. _Lorain_: Oberlin. +_Lucas_: Lake Erie at Reno Beach, Jerusalem Twp.; Lake Erie, 1/2 mi. +offshore from mouth of Crane Creek; Maumee River at Maumee; Swan +Creek, W of Toledo; "near" Waterville; Swan Creek "near" Whitehorse. +_Madison_: London. _Medina_: Hinckley Lake. _Meigs_: Shade River, +below Darwin. _Miami_: Miami River, above Troy. _Monroe_: Cranenest +Fork, Green Twp. _Montgomery_: Mad River, Dayton; Miami River, Dayton; +Stillwater River, Dayton. _Morrow_: Kokosing River, Franklin Twp. +_Noble_: Jct. Sharon Twp. 1 and St. Rt. 78. (Adler and Dennis, +1960:27). _Ottawa_: East Harbour, Catawba Island. _Pike_: Chenoweth +Fork, Sunfish Twp.; Scioto River, Camp Creek Twp. _Ross_: Paint Creek +near Bainbridge. _Vinton_: Lake Hope; Lake Alma. _Warren_: Fort +Ancient. _Washington_: Dam No. 2, Muskingum River, "near" Marietta. +_Williams_: 1 mi. S Blakesley; St. Joseph River "near" Blakesley; West +Branch, St. Joseph River, Sec. 8, Bridgewater Twp.; Edgerton. _Wood_: +Grand Rapids; Grassy Creek, Rossford; Haskins; Maumee River opposite +Toledo. + +PENNSYLVANIA: _Allegheny_: Monongahela River above McKeesport +(Atkinson, 1901:154); Ohio River at Pittsburgh (Wied-Neuwied _in_ +Stejneger, 1944:44, 49). _Armstrong_: (Swanson, 1952:165). _Clarion_: +Clarion River "near" Clarion (Allen, 1955:228); Foxburg (= Foxbury?, +Boulenger, 1889:260). _Crawford_: _Elk_: _Erie_: Edinboro Lake. +_Forest_: (Swanson, _loc. cit._). _Indiana_: Plum Creek; Crooked Creek +(Netting _in_ Stejneger, 1944:48). _McKean_: (Swanson, _loc. cit._). +_Somerset_: Stoyestown (Surface, 1908:122). _Warren_: _Venango_: +Allegheny River south of Franklin (Swanson, _loc. cit._). + +TENNESSEE: _Chester_: South Fork, Forked Deer River just E Henderson +(Endsley, 1954:40). _Clay_: Mill Creek, 3 mi. from Butler's Landing; +Obey River above mouth of Wolf River at Lilydale; mouth of Wolf River +(Shoup, Peyton and Gentry, 1941:75); Iron Creek "near" Willow Grove +(Stejneger, 1944:56). _Fentress_: _Jackson_: (Gentry, 1941:332). +_Lake_: Reelfoot Lake (Parker, 1948:29). _Obion_: Walnut Log (Parker, +1937:85); east shore of Reelfoot Lake, Samburg (Rhoads, 1895:386). +_Overton_: Medlock Branch, tributary of West Fork Obey River north of +Allred (Shoup, Peyton and Gentry, _loc. cit._). _Roane_: 2 mi. S +Kingston (Stejneger, 1944:55). + +VERMONT: _Chittenden_: Lake Champlain, mouth of Winooski River; "near" +Burlington; Milton (= Minton) (Babcock, 1919:420). _Franklin_: Swanton +(Stejneger, 1944:55). + +WEST VIRGINIA: _Randolph_: Tygart River at Elkins (Green, 1937:116). + +WISCONSIN: _Burnett_: _Crawford_: (Pope and Dickinson, 1928:83). +_Dane_: Lake Wingra, Madison (Noland, 1951:54). _Grant_: (Pope and +Dickinson, _loc. cit._). _Green Lake_: Berlin (AMNH 6840-41, listed in +card file March 2, 1959). _Jefferson_: Lake Mills (Dickinson, +1950:75). _La Crosse_: West Salem (Pope, 1930:281). _Oneida_: _Pepin_: +(Pope and Dickinson, _loc. cit._). _Racine_: Eagle Lake (Edgren, +1944:498); Burlington; Rochester (Stille and Edgren, 1948:201). +_Sheboygan_: Sheboygan (KKA). _Trempealeau_: _Vernon_: "near" Viroqua +(Pope, _loc. cit._). _Walworth_: Lake Beulah (Dickinson, _loc. cit._). +_Washburn_: (Pope and Dickinson, _loc. cit._). _Waukesha_: Lac La +Belle (Cahn, 1929:8). _Winnebago_: Wolfe River (Dickinson, _loc. +cit._). + + +=Trionyx spinifer hartwegi= (Conant and Goin) + +Western Spiny Softshell + +Plates 35 and 36 + + _Amyda spinifera hartwegi_ Conant and Goin, Occas. Papers Mus. + Zool. Univ. Mich., No. 510:1, pl. 1, map 1, June 15, 1948. + + _T[rionyx] s[pinifer] hartwegi_ Schwartz, Charleston Mus. Leaflet, + No. 26:11, May, 1956. + +_Type._--Holotype, UMMZ 95365; alcoholic adult male; obtained at +Wichita, Sedgwick County, Kansas, in May, 1945, by Robert Young. + +_Range._--Central United States in tributaries flowing into the +Mississippi River from the west, except the Red River drainage; +eastern Montana, North Dakota, and southern Minnesota south to eastern +Colorado, northern Oklahoma and Arkansas (see map, Fig. 19). + +_Diagnosis._--Juvenal pattern of small ocelli, rarely as large as two +millimeters in diameter, or usually solid black dots that are not +much larger in center of carapace than at sides (mean OD/PL, Kansas, +.022); only one dark marginal line separating pale rim of carapace +from dorsal ground color. + +_Description._--Plastral length of smallest hatchling, 2.8 centimeters +(USNM 9928); of largest male, 13.1 centimeters (USNM 55687); of +largest female, 25.5 centimeters (KU 2283). + +Carapace olive, having small ocelli or black spots that are not much +larger in the center of the carapace than at the sides; pale rim of +carapace separated from darker ground color by one dark marginal line +and not four or five times wider posteriorly than laterally; large +females often having black dots at sides of carapace on mottled and +blotched pattern; pattern on snout of pale, dark-bordered stripes that +unite forming acute angle in front of eyes; well-defined dark markings +in subocular and postlabial region; pattern contrasting with ground +color on side of head; postlabial stripe broken, interrupted; pale +postocular stripe having blackish borders interrupted, not joining +with postlabial stripes; dorsal surface of soft parts of body having +contrasting pattern, largest blackish marks on hind limbs; elongate +tail of males having pale dorsolateral bands with well-defined, lower, +blackish borders; patterns on soft parts of body usually obscured or +absent on large females; underparts whitish, often having blackish +marks, except in center of plastral area; dark marks on webbing of +limbs, palms and soles; dark streaks often coincident with digits; +tubercles along anterior edge of carapace small and conical on adult +males, and conical or knoblike on large females; accessory, knoblike +tubercles in nuchal region and in middle of carapace posteriorly on +large females. + +Ontogenetic variation in PL/HW, mean PL/HW of specimens having +plastral lengths 7.0 centimeters or less, 4.24, and exceeding 7.0 +centimeters, 5.33; ontogenetic variation in CL/CW, mean CL/CW of +specimens having plastral lengths 8.5 centimeters or less, 1.12, and +exceeding 8.5 centimeters, 1.19; mean CL/PCW, 2.00; mean SL/HW, 1.30 +(including subspecies _spinifer_); mean CL/PL, 1.38. + +_Variation._--Variants include: CNHM 8949, UMMZ 72511 and TU 14591 +having ocelli approximately 4 millimeters in diameter that are almost +solid spots; KU 17728 having pale stripes on snout that lack black, +inner borders; TTC 719 (female, plastral length 20.7 cm.), having +distinct pattern on snout; USNM 14535, 17823, 55684, and 123446 (from +different localities) having markings confined to margins of carapace +(Stejneger, 1944:66, suggested that USNM 17823 probably came from +Texas); UMMZ 92667 (female, plastral length 6.7 cm.) lacking pattern +on carapace. + +_Comparisons._--_T. s. hartwegi_ can be distinguished from all other +subspecies of _T. spinifer_ by the presence of small dots and ocelli +on the carapace that are all of approximately the same size in +combination with only one dark marginal line. _T. s. hartwegi_ +resembles _asper_ in having small blackish ocelli or dots on the +carapace but differs from _asper_ in having only one dark marginal +line. _T. s. hartwegi_ differs from _spinifer_ only in the small size +of the ocelli. _T. s. hartwegi_ resembles _spinifer_ and _asper_, but +differs from _pallidus_, _guadalupensis_ and _emoryi_ in having +blackish spots and ocelli on the carapace and lacking small whitish +spots. _T. s. hartwegi_ resembles _spinifer_, _asper_ and _pallidus_ +but differs from _guadalupensis_ and _emoryi_ in having conical or +knoblike tubercles on the anterior edge of the carapace on large +females. + +_T. s. hartwegi_ differs from the subspecies _asper_, _guadalupensis_ +and _emoryi_ in having a narrower head, and from _emoryi_ in having a +wider carapace. _T. s. hartwegi_ resembles _spinifer_ and _asper_ but +differs from the other subspecies in having the carapace widest at a +plane approximately one-half way back on the carapace. _T. s. +hartwegi_ and _spinifer_ have longer snouts than do _pallidus_ and +_guadalupensis_ or _emoryi_. _T. s. hartwegi_ differs from _asper_ but +resembles the other subspecies in having a relatively longer plastron. + +_Remarks._--The validity of _T. s. hartwegi_ has never been +questioned. It intergrades with _spinifer_ over a broad area +paralleling the Mississippi River. For convenience, specimens +occurring west of the Mississippi River are referred to the subspecies +_hartwegi_. Figure 8 shows much variation in size of ocelli on +different individuals from the same state. For example, UMMZ 92667, +plastral length 6.7 centimeters has a uniform pale brown carapace +lacking any dark marks, whereas UMMZ 92652, plastral length 5.9 +centimeters has some ocelli three millimeters in diameter on the +carapace. Both are from Iowa. One specimen from Kansas, KU 1954 +(Doniphan County, plastral length 11.8 cm.), has ocelli four +millimeters in diameter, and USNM 7648 captured farther west at Fort +Laramie, Wyoming, an adult male having a plastral length of 11.0 +centimeters, has some ocelli five millimeters in diameter on the +carapace. TTC 1090, an adult male from the panhandle of Texas has some +ocelli so much as 5.5 millimeters in diameter. The size of the ocelli +seemingly varies in the same local population. + +Specimens of _T. spinifer_ in the lower Mississippi Valley are +intergrades. Most individuals have small black dots on the carapace; +some have small ocelli (TU 7216, 7501, 11912, 12123-24) interspersed +with black dots (TU 5863), others have black dots confined to the edge +of the carapace (TU 157, 4539, 7105), and still others have no pattern +on the carapace (TU 7506, 13698.1, 10087.6). Two large males (TU +11580, 13025) have large ocelli (approximately five mm. in diameter) +that have nearly black centers. In general, there is more dark +pigmentation than farther north; some specimens have extensive +pigmentation on the ventral surface of the carapace and soft parts of +the body (TU 156, 5648). The dorsal surface of the limbs, especially +the hind limbs, have a bold, black marbling and may be almost +completely black (TU 5484, 5597). Many females, not exceeding plastral +lengths of 7.0 centimeters, have a pale blotched pattern of lichenlike +figures or have ill-defined black dots on the carapace (TU 10087, +13698.13, 13753.15). + +Localities of specimens of _T. spinifer_ occurring in the Mississippi +River drainage in Mississippi are arbitrarily listed under the account +of the subspecies _spinifer_, whereas those in Louisiana (excluding +_pallidus_) are listed under the account of _hartwegi_. + +Neither Over (1943) nor Wheeler (1947:169) record _T. s. hartwegi_, +respectively, from South Dakota or North Dakota; records from the +Missouri River drainage in Montana suggest the occurrence of the +species in that drainage in North and South Dakota. + +_Specimens examined._--Total, 392 as follows: ARKANSAS: _Clay_: UMMZ +70735 (2), 7 mi. S St. Francis. _Crawford_: USNM 95352, Lee Creek, 7 +mi. NW Natural Dam. _Drew_: CNHM 40785. _Lafayette_: KU 2225-29, 2944 +(one of three specimens bearing last catalog number), 2963 (one of +three specimens bearing this catalog number), 2964 (one of two +specimens bearing this catalog number), Lewisville (see remarks under +the account of the subspecies _pallidus_). _Lawrence_: CNHM 8949; +CNHM 12598-600, 12602-04, TU 5855, UI 2413, Imboden; UI 2412, Black +River at Powhatan. _Marion_: TU 14591 (6), White River at Cotter. +_Prairie_: KU 1867, 1869, 1879, 1949-51, 2280-83, 2285-91 (2 specimens +bear catalog number 2287), 2307, 2761-62, 2666, 2826, 2842, 3346-47, +White River at DeValls Bluff. _Pulaski_: UMMZ 96540, Little Rock. +_Saline_: USNM 17823, Saline River at Benton. _Searcy_: UMMZ 92755, +Little Red River, 1.5 mi. SE Leslie. _Yell_: TU 14565, Petit Jean +Creek, 10 mi. N Casa. _County unknown_: CNHM 28566-67, Ouachita River. + +IOWA: _Allamakee_: UMMZ 72556-58, 92642-49, Mississippi River "near" +Lansing. _Appanoose_: UMMZ 92667, Chariton River, 4.3 mi. N. +Centerville. _Decatur_: UMMZ 92651, Grand River, 3.5 mi. WSW Decatur. +_Dickinson_: UMMZ 55249, Milford; UMMZ 92655, Spirit Lake Twp. +_Hamilton_: USNM 9928, Webster City. _Hardin_: UMMZ 92650, Eldora. +_Louisa_: UMMZ 92654, Muscatine Slough, 12 mi. SW Muscatine, Muscatine +County. _Muscatine_: INHS 7675, 5.5 mi. SE Muscatine; USNM 54730-32, +Fairport. _Scott_: CNHM 433, Davenport; UMMZ 92656, Steamboat Slough, +2 mi. N Princeton. _Story_: UMMZ 92653, Squaw Creek at Ames. +_Washington_: UMMZ 92652, English River, 2 mi. E Riverside. + +KANSAS: _Anderson_: KU 52286-87, 3-1/4 mi. E, 1/2 mi. N Colony. +_Atchison_: UMMZ 66939-41, Atchison. _Barber_: KU 17728, 4.5 mi. S Sun +City; KU 41379, 41742, 6 mi. N, 3.5 mi. E Sharon; USNM 100580, +Medicine River, 1 mi. S Lake City. _Cherokee_: KU 1323, Galena. +_Comanche_: KU 18385, 3-4 mi. SE Arrington. _Cowley_: UMMZ 75963, USNM +90441-44, 91022, 100529-30, "near" Winfield. _Doniphan_: KU 1943, +1952-54, Doniphan Lake. _Douglas_: KU 1955-56, Wakarusa River; KU +40176-77, Kansas River at Lawrence. _Franklin_: KU 3290. _Hamilton_: +KU 2990, Syracuse. _Harper_: KU 18159, 1 mi. N Harper. _Kingman_: USNM +95261, 2 mi. E Calista. _Labette_: KU 3339. _Lane_: KU 3738-41, +Pendennis. _Logan_: KU 16531, Smoky Hill River, 3 mi. SW Elkader. +_Meade_: KU 40210, Crooked Creek, 12.5 mi. S, 1-1/4 mi. W Meade. +_Montgomery_: KU 3731-32, Independence; KU 50856, Cherryvale Lake. +_Neosho_: UMMZ 69294, Caneville Creek, 32 mi. N. Parsons, Labette +County. _Osage_: KU 3294-96, Appanoose Creek. _Pratt_: KU 15931-32, +15934, State Fish Hatchery "near" Pratt. _Riley_: KU 48239, McDowell +Creek, WSW Manhattan; UMMZ 64434, "near" Manhattan. _Russell_: KU +3289. _Sedgwick_: UMMZ 95363-65, Wichita. _Shawnee_: USNM 123446, +Kansas River at Topeka. _Stafford_: KU 3758, Little Salt Marsh; KU +41743, 13.5 mi. N, 6 mi. E Stafford. _Trego_: KU 2757, 3769, Smoky +Hill River, 10 mi. N (NNE) Utica, Ness County; KU 51517, Saline River, +5 mi. N, 1/2 mi. E Wakeeney. _Wilson_: KU 56744-45, Verdigris River, 1 +mi. S Altoona. _Woodson_: KU 55295, Neosho River, 1/2 mi. E, 1-1/2 mi. +S Neosho Falls. _County unknown_: USNM 51529. + +LOUISIANA: _Catahoula_: TU 12629, Ouachita River, 4 mi. N +Harrisonburg. _Claiborne_: TU 13080, Caney Lake "near" Summerfield. +_Concordia_: KU 50849, Tensas River at Clayton; TU 16524 (3), USNM +012349, Lake Concordia; USNM 99865, Red River "near" Shaw. _East +Carrol_: TU 827-30, 905, 5644-45, Lake Providence. _Grant_: TU 12735, +Big Creek at Fishville, "near" Pollock. _Jefferson_: TU 5592-98, 7184, +10741, 10171, Mahogany Pond. _Lafourche_: TU 7105, 7132, 7216, 7501, +7505-07, 10087 (14), 11828-29, 11912, 11983 (2), 12123-28, 13502, +13679 (8), 13753 (22), 13766.2, Bayou Lafourche at Raceland. +_Morehouse_: USNM 11631 (2), Mer Rouge. _Natchitoches_: USNM 100420, +Cane River "near" Natchitoches. _Orleans_: TU 16169 (3), Audubon Park, +New Orleans; USNM 029310, "near" New Orleans. _Ouachita_: TU 12916, +12954, 12970-71, 13019, 13025, Bartholomew Bayou at Sterlington; TU +5988, Monroe. _Pointe Coupee_: TU 153, 156-59, 165, 5484, 5513, +5518-19, 5646, 5648, 5651, USNM 100202-12, False River at New Roads. +_Rapides_: TU 14040, Red River at Rapides. _Richland_: OU 25082. _St. +Bernard_: TU 16170, Delacroix Island. _St. Charles_: TU 4539, 4579, +5224, 5990, 11928 (12), 13698 (16), Bayou Gauche between Paradis and +Des Allemands; TU 5863, 11580, Bonnet Carre Spillway at Norco. +_Tensas_: TU 5762, Lake St. Joseph near Newellton. _Union_: USNM +138946, Meridian Creek, 1 mi. E Conway; USNM 138947, Ouachita River, +Alabama Landing. _Parish unknown_: MCZ 1622, Lake St. John (Concordia +or Tensas Parish); USNM 029266, Louisiana? + +MINNESOTA: _Hennepin_: AMNH 4759-60, Fort Snelling. _Lesueur_: KU +46742-43, Waterville, Lake Tetonka. _Winona_: USNM 59263-66, Homer. + +MISSOURI: _Carter_: UMMZ 70737, "near" Van Buren. _Chariton_: UI +17509, Triplett. _Franklin_: USNM 55689. _Gasconade_: UMMZ 95900, +Bourbeuse Creek, 8 mi. S Owensville. _Jefferson_: USNM 95405, Glaize +Creek. _Lewis_: USNM 59279-80, Canton. _Miller_: UMMZ 91929, Barren +Fork Tavern Creek, 5 mi. NW Iowna. _Newton_: UMMZ 82822, Shoal Creek, +12 mi. W Momit. _Phelps_: UMMZ 91930, Bourbeuse River, 10 mi. N St. +James. _Reynolds_: CNHM 35392, Black River at Warner Bay Spring; USNM +55688. _Ripley_: UMMZ 90435. _Shannon_: INHS 6223, Alley Spring State +Park. _St. Charles_: USNM 93089-94, Dardenne Creek, St. Peters. _St. +Louis_: USNM 55685-87, Mississippi River at St. Louis. _Stone_: USNM +55684. _Washington_: USNM 55690. _Wayne_: UI 16554, Sam A. Baker State +Park; UMMZ 95879, St. Francis River at Lodi. _County unknown_ (Wayne +or Butler): UMMZ 83264, Clark National Forest, St. Francis River. + +MONTANA: _Big Horn_: USNM 54421, Crow Agency. _Roosevelt_: USNM 58, +Fort Union (locality reads "Yellowstone, Fort Union"; probably the +Yellowstone River near Fort Union). _Wheatland_: UMMZ 92005, +Musselshell River near Shawmut. _Yellowstone_: USNM 14535, Custer. + +OKLAHOMA: _Alfalfa_: OU 9316, 2 mi. S Cherokee. _Cleveland_: OU 22973, +Norman. _Delaware_: UMMZ 81476, Spavinaw. _LeFlore_: OU 16802, 1.5 mi. +E Zoe. _Osage_: UMMZ 89628, Big Hominy Creek. _Pottawatomie_: OU +25175, 5 mi. SW Shawnee. _Rogers_: OU 7317, Verdigris River, 5 mi. W +Claremore; UMMZ 81473-74, near Garnett, Tulsa County; UMMZ 81475, 4 +mi. NE Inola. _Sequoyah_: OU 9008, 2 mi. NE Gore; TU 13885, Little +Vian Creek, 1 mi. E Vian. _Texas_: OU 5005, 5 mi. SE Guymon. _Tulsa_: +TU 17061, Bird Creek "near" Skiatook, Osage County. _Woods_: CHNM +11809, Waynoka; OU 9432, 2.5 mi. W Waynoka; OU 9579, 9581-82, 1 mi. S +Waynoka. + +TEXAS: _Hansford_: TTC 719, 10 mi. S, 2 mi. W Gruver. _Hutchinson_: +TTC 1090, Carson Creek, Turkey Track Ranch. + +WYOMING: _Goshen_: USNM 7648, Fort Laramie. _Weston_: UMMZ 78080, +Beaver Creek. + +NO DATA: CNHM 21687-88, 22925. SM 142 (locality of Waco, McLennan +County, Texas, believed in error). USNM 7649, 11625, 19622-23, 36412 +(Illinois River). + +_Records in the literature._--ARKANSAS: _Benton_: (Dowling, 1957:37). +_Chicot_: Lake Chicot. _Clark_: Terre Noir Creek, 13 mi. W +Arkadelphia. _Garland_: Ouachita River, Mountain Pine (Conant and +Goin, 1948:7). _Hempstead_: _Jefferson_: (Dowling, _loc. cit._). +_Lawrence_: Black Rock (Dellinger and Black, 1938:46). _Madison_: +_Scott_: _St. Francis_: (Dowling, _loc. cit._). _Washington_: near +Greenland (Dellinger and Black, _loc. cit._). + +COLORADO: _Boulder_: Boulder Creek, E Boulder; Boulder Creek, 6 mi. S +and 1 mi. E Longmont. _Larimer_: Cache la Poudre River. _Logan_: 8 mi. +NE Sterling. _Morgan_: Platte River "near" Fort Morgan. _Otero_: +Purgatoire River at Higbee. _Prowers_: Arkansas River at Lamar. +_Weld_: Poudre River "near" Greeley; Evans. _Yuma_: Bonny Dam, +Republican River (Maslin, 1959:24-25). + +IOWA: _Dickinson_: Little Sioux River, Okoboji Twp. (Blanchard, +1923:24). _Story_: Skunk River, 5 mi. NNE Ames (Conant and Goin, +1948:9). + +KANSAS: _Allen_: Petrolia (KKA). _Barber_: 7 mi. S Sun City. _Butler_: +3 mi. SE Augusta (Burt and Hoyle, 1934:198). _Chase_: 10 mi. SW Olpe; +7 mi. SW Saffordville (Breukelman and Smith, 1946:112). _Cherokee_: +tributary of Spring River, 1 mi. N Riverton (Hall and Smith, +1947:451). _Coffey_: (Smith, 1956:160, symbol on map). _Cowley_: 11 +mi. SE Winfield (Stejneger, 1944:55). _Crawford_: Pittsburg (Hall and +Smith, _loc. cit._). _Doniphan_: "near" Geary (Linsdale, 1927:81). +_Elk_: (Smith, _loc. cit._). _Ellis_: Big Creek (Brennan, 1934:190); +Ellis (Conant and Goin, 1948:2). _Franklin_: Middle Creek, SE part of +county (Gloyd, 1928:135). _Greenwood_: (Stejneger, _op. cit._:54). +_Leavenworth_: Missouri River "near" Fort Leavenworth (Brumwell, +1951:208). _Lyon_: 5 mi. E Emporia (Breukelman and Smith, _loc. +cit._). _Marion_: (Smith, _loc. cit._). _Meade_: Meade County State +Park, _ca._ 13 mi. SW Meade (Tihen and Sprague, 1939:505). _Ness_: +5.5 mi. NW Ness (Breukelman and Smith, _loc. cit._). _Osage_: Marais +des Cygnes River; Long and Jordan Creeks (Clarke, 1958:21). _Reno_: 6 +mi. E Turon. _Sedgwick_: 2 mi. NE Cheney (Burt, 1935:321). _Sheridan_: +State Lake 7 mi. NE Quinter, Gove County (Breukelman and Smith, _loc. +cit._). _Wabaunsee_: Dragoon Creek at Harveyville (Clarke, 1956:215). +_Wallace_: (Burt, 1933:208). _Wilson_: Fall River, 1/2 mi. S Neodesha +(Clarke, _loc. cit._). + +MINNESOTA: _Anoka_: _Benton_: _Chisago_: (Breckenridge, 1944:184, +symbols on map). _Crow Wing_: (Breckenridge, _op. cit._:185). +_Dakota_: (Hedrick and Holmes, 1956:126). _Goodhue_: (Breckenridge, +_op. cit._:184, symbol on map). _Hennepin_: Minneapolis; Lake +Minnetonka (Breckenridge, _op. cit._:187); 5 mi. N. Minneapolis +(Breckenridge, 1955:5). _Houston_: Root River near Hokah. _Lesueur_: +Lake Washington (Hedrick and Holmes, _loc. cit._). _Meeker_: Swan Lake +(Breckenridge, 1957:232). _Pine_: (Breckenridge, 1944:185). _Ramsey_: +_Rice_: _Sherburne_: _Stearns_: (Breckenridge, _op. cit._:184, symbols +on map). _Washington_: just north of Stillwater (Hedrick and Holmes, +_loc. cit._). _Winona_: Winona (Breckenridge, _op. cit._:187). _Yellow +Medicine_: (Breckenridge, _op. cit._:185). _County unknown_ (Goodhue +or Wabasha): Lake Pepin (Breckenridge, _op. cit._:184). + +MISSOURI: _Boone_: east of Ashland (Henning, 1938:92). _Jackson_: +Missouri River "near" Atherton (Anderson, 1942:219). _Jefferson_: +Mississippi River "near" mouth Glaize Creek at Sulphur Springs; Glaize +Creek at Barnhart (Boyer and Heinze, 1934:199). _St. Clair_: Osage +River "near" Osceola. _Vernon_: Marmaton River, 7 mi. N Moundville +(Conant and Goin, 1948:9). + +MONTANA: Yellowstone River (Conant and Goin, 1948:9). + +NEBRASKA: _Adams_: 1 mi. N Ayr (Hudson, 1942:101). _Dawson_: 2 mi. SE +Gothenburg (Gehlbach and Collette, 1959:142). _Franklin_: 2 mi. SW +Naponee. _Gage_: 1 mi. W Barnston. _Hitchcock_: 3 mi. E Stratton. +_Holt_: Elkhorn River "near" Atkinson. _Lancaster_: Lincoln (Hudson, +_loc. cit._). _Lincoln_: 1 mi. S Sutherland (Gehlbach and Collette, +_loc. cit._). _Red Willow_: 14 mi. NW McCook. _Richardson_: 2 mi. S +Rulo. _Wheeler_: 2 mi. W Ericson (Hudson, _loc. cit._). + +OKLAHOMA: _LeFlore_: Wister (Conant and Goin, 1948:9); Shady Pointe +(KKA); Poteau River, 6.5 mi. W Heavener (Trowbridge, 1937:301). +_Tulsa_: Arkansas River "near" Tulsa (Force, 1930:38). + +WYOMING: _Goshen_: Platte River (Conant and Goin, 1948:10). + + +=Trionyx spinifer asper= (Agassiz) + +Gulf Coast Spiny Softshell + +Plates 37 and 38 + + _Aspidonectes asper_ Agassiz, Contr. Nat. Hist. United States, + 1(Pt. 2):405; 2(Pt. 3):pl. 6, fig. 3, 1857. + + _Trionyx spinifer asper_ Schwartz, Charleston Mus. Leaflet, + No. 26:17, pls. 1-3, map 2, May, 1956. + + _Platypeltis agassizii_ Baur, Amer. Nat., 22:1121, 1888. + +_Type._--Lectotype, MCZ 1597; alcoholic female; locality designated as +Pearl River, Columbus, Marion County, Mississippi; received from Mr. +Winthrop Sargent of Natchez, Mississippi. + +_Range._--Southeastern United States except peninsular Florida from +the Florida Parishes of Louisiana east to southern North Carolina; +Gulf Coast drainage including that of Lake Pontchartrain, Louisiana, +eastward to the Apalachicola River system, and Atlantic Coast drainage +including that of the Altamaha River in Georgia northward to the Pee +Dee River drainage in South Carolina (see map, Fig 19). + +_Diagnosis._--Juvenal pattern of black ocelli and spots, and two or +more black, interrupted, lines paralleling rear margin of carapace; +pale postocular and postlabial stripes often united on side of head; +length of plastron short. + +_Description._--Plastral length of smallest hatchling, 2.9 centimeters +(USNM 134244); of largest male, 13.2 centimeters (TU 17117); of +largest female, 27.0 centimeters (TU 13474). + +Blackish marginal rings on carapace number two, three or four +posteriorly, but decrease in number anteriorly; segments of marginal +rings may extend to nuchal region; marginal rings increasingly +interrupted inwardly; pattern of hatchlings having well-defined +marginal rings that are not extensively interrupted (often males), or +having marginal rings broken into small segments or series of dots, +and pale outer margin of carapace marked by ill-defined, hazy, inner +border (often females); conspicuous marginal rings often lacking on +hatchling females; pale rim of carapace not four or five times wider +posteriorly than laterally; carapace having blackish dots, spots, +small ocelli or a combination thereof; marks on carapace of slightly +varying sizes, some occasionally barlike (usually males); some +hatchling females showing pale, irregular blotching on carapace, often +characterized by small lichenlike figures superimposed on blackish +dots. + +Striping on snout variable; pale, dark-bordered stripes usually unite +in front of eyes and form right or acute angle; medial dark borders of +pale stripes on snout not joined anteriorly, broken into segments or +dots, reduced to single median line, united to form straight line +connecting anterior margins of orbits (usually with slight medial +indentation), or absent; pale postocular and postlabial stripes often +joined, relationship variable and on either side of head; side of head +with or without dark markings, sometimes a pale subocular blotch +bordered below by a dark line; pattern on dorsal portions of soft +parts of body contrasting, less so on limbs of hatchlings; pattern of +irregular dark marks, dark streaks usually coincident with digits; +longitudinal streaks often occur on neck; elongate tail of adult males +usually having well-defined, dorsolateral, pale bands with dark lower +border more diffuse than upper border. + +Underparts whitish often with dusky markings on rear of carapace or in +region of bridge; blackish marks often on webbing and portions of +soles and palms, and chin and throat. + +Small conical tubercles along anterior edge of carapace on adult +males; remnants of juvenal pattern usually present on carapace of +large females; conical or knoblike tubercles on anterior edge of +carapace of large females; accessory knoblike tubercles in nuchal +region (a paravertebral pair usually most prominent), and posteriorly +in middle of carapace on large females. + +Ontogenetic variation in PL/HW, mean PL/HW of specimens having +plastral lengths 7.0 centimeters or less, 3.87, and exceeding 7.0 +centimeters, 4.94; ontogenetic variation in CL/CW, mean CL/CW of +specimens having plastral lengths 8.5 centimeters or less, 1.11, and +exceeding 8.5 centimeters, 1.16; mean CL/PCW, 1.71; mean CL/PL, 1.45. + +_Variation._--The sex of some hatchlings can be distinguished by the +pattern on the carapace (see Plate 37 for different patterns), but the +sex of many hatchlings cannot be distinguished on the basis of +pattern. + +In the early stages of this study, I thought that the pattern on the +carapace differed in eastern and western populations, and that the +zone of intergradation was in Alabama. Adult males from the +Tombigbee-Alabama river drainage and westward were noted to have +blackish spots (some slightly ocellate) intermixed with few, if any, +smaller blackish dots, whereas the adult males from east of the +Tombigbee-Alabama river drainage had many small, black dots intermixed +with slightly larger, mostly ocellate marks (see Plate 38, left, top +and bottom, for contrast); also, hatchlings from western populations +were never observed to have four marginal rings. On the basis of +pattern, I would have thought that the individual having many ocelli, +that lacks correct locality data and that is photographed by Stejneger +(1944:Pl. 26), came from Georgia or South Carolina; but, the pattern +(_op. cit._:Pl. 27) of a specimen, probably an adult male, from South +Carolina, resembles the pattern on adult males from Louisiana. The +differences noted above are probably due to individual variation +rather than geographic variation. + +Color notes taken from life of a freshly-killed adult male (TU 16071, +Louisiana) are: carapace olive, spots blackish, outer rim buff; top of +head olive, postocular and postlabial stripes yellow with blackish +borders, stripes on snout buff with blackish borders; dorsal ground +color of soft parts of body pale olive-green, larger marks blackish, +ground color laterally toward juncture of pattern and immaculate +undersurface, and toward insertions of neck and limbs becoming +yellowish; webbing on hind limbs having reddish tinge; dorsolateral +bands on tail yellow with blackish borders; undersurface whitish; chin +and throat olive-green with blackish marks; becoming buff then whitish +posteriorly. + + [Illustration: FIG. 20. Basicranial length and ratio of greatest + diameter of internal choanae to least width of maxillary + bridge (IC/MB) on 30 skulls of _T. ferox_ (open circles), + 26 of _T. spinifer_ (crosses), and 12 of the _agassizi_-form + (solid circles; half shaded circle represents holotype of + _agassizi_). Skulls of the _agassizi_-form tend to have + slightly smaller internal choanae than those of _spinifer_ + or _ferox_.] + +Occasional specimens have only one definite dark line paralleling the +rear margin of the carapace. Schwartz (1956:16) reported that +Charleston Museum No. 55.159.26 has only one solid line at the margin +of the carapace, and I received an adult male (KU 47120) reported to +have come from the Pearl River that is aberrant in not having more +than one dark marginal line. USNM 95191, a large stuffed female from +the Pearl River is mentioned by Stejneger (1944:59, Pl. 17) as having +marks that "assume the form of short lines parallel with the +submarginal ring"; I examined this specimen and noted that it had only +one dark marginal line. Stejneger (_op. cit._:64) mentioned another +from the Pearl River drainage, and Crenshaw and Hopkins (1955:20) +wrote that some individuals from Georgia have only one dark marginal +line. Presumably MCZ 1606 (now in the Albany Museum) recorded by +Stejneger (_op. cit._:52) as _Amyda s. spinifer_ from Columbus, +Georgia, is another specimen. + + [Illustration: FIG. 21. Basicranial length and greatest width of + alveolar surface of maxilla on 52 skulls of _T. spinifer_ (open + circles) and 11 of the _agassizi_-form (solid circles; half shaded + circle represents holotype of _agassizi_). Most skulls of the + _agassizi_-form that exceed 43 mm. in basicranial length have a + more expanded, alveolar surface of the maxilla than skulls of + _spinifer_ of approximately the same size. All skulls exceeding + 50 mm. are those of females.] + +Some skulls of soft-shelled turtles from streams of the Atlantic Coast +drainage, including the skull of the holotype of _Platypeltis_ (= +_Trionyx_) _agassizi_ Baur (MCZ 37172, Pl. 54), show at least two +differences from other skulls of _asper_ and from those of other +subspecies of _T. spinifer_. Figure 20 shows that skulls of _agassizi_ +tend to have slightly smaller internal choanae (ratio IC/MB) than +those of _T. spinifer_ and _T. ferox_; there is seemingly little +difference between skulls of _ferox_ and _spinifer_, and little, if +any, ontogenetic variation. Figure 21 shows that most skulls of the +_agassizi_-form that exceed 43.0 millimeters have a more expanded, +alveolar surface of the maxilla than skulls of _spinifer_ of +approximately the same size; most skulls exceeding a basicranial +length of 43.0 millimeters, and certainly all skulls exceeding 50.0 +millimeters are those of females. Stejneger (1944:Pl. 30) also has +provided photographs of a skull of the _agassizi_-form. It is of +interest that of the 12 _agassizi_-form skulls (MCZ 37172; USNM 8708, +029034, 51981, 66859, 71681, 91282, 91310-11, 92521, 92583-84) that I +examined some resemble _ferox_ (Neill, 1951:9) in having the alveolar +surfaces of the jaws broadened, and the greatest width at the level of +the quadratojugal (Table 3, Plate 54); also, the localities of all 12 +skulls are within the geographic range of _ferox_. Skulls of _ferox_, +however, have conspicuously broadened alveolar surfaces of the jaws +only when they exceed in length the largest skulls of _agassizi_. The +differences of skulls of the _agassizi_-form possibly reflect +isolation in the Atlantic Coast drainage, and an adaptation in feeding +habits. So far as I can ascertain, individuals occurring in rivers of +the Atlantic Coast drainage in Georgia and South Carolina (referable +to _agassizi_) do not differ consistently in external characters from +individuals of _T. s. asper_ that occur westward in the Apalachicola +drainage. + +_Comparisons._--_Trionyx s. asper_ can be distinguished from all other +subspecies of _T. spinifer_ by usually having more than one black line +paralleling the rear margin of the carapace. This character and the +frequent fusion of the postlabial and postocular stripes on the side of +the head distinguish _asper_ from _spinifer_ and _hartwegi_. _T. s. +asper_ differs from _pallidus_, _guadalupensis_ and _emoryi_ in having +blackish spots and ocelli on the carapace, and lacking whitish dots or +tubercles. _T. s. asper_ resembles _spinifer_, _hartwegi_ and _pallidus_ +but differs from _guadalupensis_ and _emoryi_ in having conical +tubercles along the anterior edge of the carapace in large females. For +additional differences see accounts of other subspecies. + +Of the subspecies of _T. spinifer_, _asper_ has a proportionately wide +head that is closely approached in the subspecies _guadalupensis_ and +_emoryi_; _T. s. asper_ differs from _guadalupensis_ and _emoryi_ in +having a wider carapace, and resembles _hartwegi_ and _spinifer_, but +differs from the other subspecies in having the carapace widest at a +plane approximately one-half way back on the carapace. _T. s. asper_ +differs from the other subspecies in having the shortest plastron. + +_Remarks._--Stejneger (1944:72-74) has discussed the history of Baur's +_Platypeltis agassizi_. Briefly, Agassiz's description of _Platypeltis +ferox_ wherein he (1857:402) states that "The young ferox [Pl. 6, fig. +3] has two or three concentric black lines separating the pale margin +...," was applicable to _T. s. asper_. Agassiz mentioned also that the +young of his _Aspidonectes asper_ (_op. cit._:406) "as in Platypeltis +ferox, ... has ... two or three black lines separating the pale rim of +the posterior margin, ..."; however, _A. asper_ was distinguished +chiefly by the "... prominent warts of the bony plates (_loc. cit._)." +Because the description of the pattern of _ferox_ resembled that of +_asper_, the validity of _asper_ was not agreed upon by all workers. +Boulenger (1889:245, footnote 1) referred to _asper_ as a species that +required "... further investigation." + +Baur (1888:1121) realized that Agassiz's description of _ferox_ was not +that of _Testudo ferox_ Schneider, and regarded the description of +Agassiz as applying to a new species, which he named _Platypeltis +agassizii_; Baur (_op. cit._:1122) also recognized _asper_, referring it +to the genus _Aspidonectes_. Baur designated a specimen from Georgia +(the only individual seen by him) as the type of _agassizi_ (Stejneger, +_op. cit._:73, footnote); this specimen is now MCZ 37172. Five years +later (1893:218), Baur discussed generic relationships of trionychids, +seemingly only on the basis of skulls (holotype of _agassizi_ not +mentioned), and referred _agassizi_ to the resurrected genus +_Pelodiscus_ Fitzinger, 1835, which was distinguished from the other two +American genera that Baur recognized (_Platypeltis_ and _Amyda_) by +having the "Posterior nares reduced in size by the inner and posterior +extension of the maxillaries." Baur also transferred _asper_ to the +genus _Platypeltis_, and restricted the type locality of that species to +"Lake Concordia, La." (_op. cit._:220); the type locality of _agassizi_ +was restricted to "Western Georgia" (_loc. cit._). + +The name-combination, _Pelodiscus agassizi_, was not generally accepted. +Hay (1892:144) and Siebenrock (1924:188) referred _agassizi_ to the +genus _Trionyx_. Hay regarded _agassizi_ as a full species (see +discussion by Stejneger, 1944:73), whereas Siebenrock considered it a +subspecies of _spiniferus_; both authors regarded _asper_ as a synonym +of _agassizi_. Neither _asper_ nor _agassizi_ was mentioned in the first +three editions of the Check List of North American Amphibians and +Reptiles (Stejneger and Barbour, 1917, 1923, 1933); the same authors in +the fourth (1939:171, 172) and fifth editions (1943:212, 213) listed +_agassizi_ as a full species, and _asper_ as a subspecies of +_spinifera_. Stejneger (1944) used the same arrangement as set forth in +the fourth and fifth editions of the Check List, and distinguished +_agassizi_ on the basis of cranial characters, namely, the small size of +the internal choanae, the greater width of the alveolar surface of the +lower jaw, and the position of the suture between the palatine and +basisphenoid relative to the posterior edge of the temporal fossa. Neill +(1951:9) regarded the peculiarities of the _agassizi_-type skull as +inconstant, but recognized _agassizi_ (and _asper_) as a subspecies of +_ferox_. Crenshaw and Hopkins (1955) showed that _asper_ did not +intergrade with _ferox_. Schwartz showed that _agassizi_ did not +intergrade with _ferox_, and regarded _agassizi_ as a synonym of _T. s. +asper_ (1956:17), but stated that _agassizi_ possessed "wider crushing +surfaces on the maxillae than does _T. s. asper_, even when skulls of +the same size and sex are compared" (_op. cit._:9). + +The holotype of _Platypeltis agassizi_ (MCZ 37172) is a dried adult +female consisting of shell, skull and limb bones; the carapace is +approximately 300 millimeters long (Schwartz, _loc. cit._). I have +examined only the skull of MCZ 37172 (Plate 54), and it is the largest +of 12 _agassizi_-type skulls I have seen. The basicranial length is 72.5 +millimeters, and the greatest width, which occurs at the level of the +quadratojugals, is 52.9 millimeters. The _agassizi_-type skulls have +been discussed under the subsection on variation. + +The type locality of _T. s. asper_, Lake Concordia, Louisiana (lower +Mississippi River drainage) as restricted by Baur (1893:220), is in an +area of intergradation of three subspecies of _Trionyx spinifer_ where +most individuals are not typical of _asper_. The syntypes, the +designation of MCZ 1597 as a lectotype, and Pearl River, Columbus, +Marion County, Mississippi, as the type locality have been discussed +elsewhere (Webb, 1960). + +The range of _T. s. asper_ overlaps that of _T. ferox_ in Georgia and +South Carolina. The two species remain distinct in the area of overlap +of their geographic ranges (Crenshaw and Hopkins, 1955:16; Schwartz, +_op. cit._:5). _Trionyx s. asper_ intergrades with _T. s. hartwegi_ and +_T. s. spinifer_ in the lower Mississippi Valley (Conant and Goin, +1948:11). + +However, there are few specimens available that indicate intergradation +of _asper_ with the _spinifer-hartwegi_ complex in the lower Mississippi +River drainage; this may be due to the fact that _asper_ inhabits +waterways that do not drain into the Mississippi River. Perhaps +intergradation is more prevalent than the morphological basis that I +have relied upon indicates; in any event, there are few specimens that +have more than one dark marginal line (which is the only character that +is unique for _asper_) from the lower Mississippi drainage. A young male +(TU 11928.9) from Bayou Gauche between Paradis and Des Allemands, St. +Charles Parish, Louisiana, has a pattern on the carapace resembling that +of _asper_; several other small softshells (TU) are available from the +same locality but none shows more than one dark marginal line. Another +specimen (USNM 95192), a young female from a barrow pit of the Big Black +River (Mississippi River drainage), Madison County, Mississippi, +resembles _asper_ in having more than one marginal ring. Of three large +females from Moon Lake, an ox-bow of the Mississippi River in Coatopa +County, Mississippi (AMNH 5285-86, 5289), only 5289 shows evidence of +two marginal lines. USNM 73669 (Greenwood, LeFlore County, Mississippi) +also indicates intergradation in that the spots tend to be linear just +inside the dark marginal line, but the specimen more closely resembles +the _hartwegi-spinifer_ complex rather than _asper_. + +There seems to be little adumbration of the dark marginal lines of +_asper_ in populations from the lower Mississippi River drainage. +Blackish spots and ocelli vary in size and there are many kinds of +pattern on the carapace. Soft-shelled turtles inhabiting the Mississippi +River and its tributaries in Louisiana and Mississippi certainly +represent an intergrading population of _spinifer_ and _hartwegi_, and, +to a lesser extent, of _asper_. Soft-shelled turtles inhabiting the +Pearl River drainage and rivers that drain into Lake Pontchartrain +immediately adjacent to the east are predominantly _asper_. + +Specimens having localities from the Pearl River and Lake Pontchartrain +drainages are listed under the account of _asper_ and are referred to +that subspecies on the distribution map; specimens from the Mississippi +drainage in Mississippi are referred to _spinifer_. + +One specimen (UMMZ 59198, Bradley County, Tennessee), from the Tennessee +River drainage where _T. s. spinifer_ occurs, deviates markedly from +_spinifer_ and suggests intergradation. UMMZ 59198, plastral length 4.8 +centimeters, has ocelli in the center of the carapace only two +millimeters in diameter, a distinct but interrupted, second marginal +ring consisting of spots, and the pale postlabial and postocular stripes +in contact on both sides of the head. + +_Specimens examined._--Total 110, as follows: ALABAMA: _Barbour_: UMMZ +113038, Chattahoochee River, Eufala. _Cherokee_: ANSP 24592, "near" +center of Terrapin Creek. _Conecuh_: UMMZ 70736, Murder Creek, +Castleberry. _Escambia_: TU 15823, Escambia River, 1 mi. N Sardine; UMMZ +70734, Escambia River at Flomaton. _Henry_: TU 15630, 3 mi. NW jct. Echo +Farm Rd. and Rt. 136 on Echo Farm Rd. _Lowndes_: UMMZ 67759, Pintlalla +Creek. _Mobile_: MCZ 1608 (2), 1608A, Mobile. _Sumpter_: USNM 83996, 3 +mi. SE Coatopa. _Tuscaloosa_: TU 14673 (5), Black Warrior River, 17.5 +mi. SSW Tuscaloosa; UA 52-1085, Cottondale. _Walker_: KU 50843, 50851, +TU 17137, Mulberry Fork, Black Warrior River, 9 mi. E Jasper. + +FLORIDA: _Calhoun_: KU 50837-38, Chipola River, 4 mi. N Scott's Ferry; +TU 16689 (4), Chipola River "near" Blountstown. _Escambia_: TU 13474, +15869 (3), 16584, Escambia River, 1.2 mi. E Century. _Okaloosa_: TU +15661, Blackwater River, 4.3 mi. NW Baker on Route 4. _Santa Rosa_: AMNH +44621, Blackwater River, Milton. _Walton_: UMMZ 110421, Pond Creek, 4 +mi. SW Florala, Covington County, Alabama. + +GEORGIA: _Baker_: TU 15889 (3), USNM 134243-48, Flint River "near" +Newton; USNM 30822. _Baldwin_: USNM 8708, Milledgeville. _Bryan_: TU +15090, Canouche River, 2.3 mi. W Groveland. _Chatham_: USNM 51981, +92583-84, Savannah. _Chattooga_: UMMZ 113037, tributary of Chattooga +River, Lyerly. _Decatur_: KU 50839-42, Flint River, 1.5 mi. S +Bainbridge. _Fulton_: UMMZ 53037, Roswell. _Lincoln_: USNM 91282-83, +above Price Island, Savannah River. _Murray_: UMMZ 59196, 9 mi. N Spring +Place. _Pulaski_: TU 14882, Ocmulgee River, 4.3 mi. SE Hawkinsville. +_Richmond_: USNM 66859, Augusta. _Whitfield_: UMMZ 74209, Cohulla Creek, +Prater's Mill "near" Dalton. _County unknown_: MCZ 37172; UMMZ 109864, +Flint River at mouth of Dry Creek; USNM 029034. + +LOUISIANA: _East Baton Rouge_: LSU 11, 1643-44, City Park Lake in Baton +Rouge; TU 17237, Amite River "near" Baton Rouge. _St. Tammany_: TU 6356, +headwater creek of Bayou Lacombe; TU 16071, USNM 66147, mouth of +Tchefuncta Creek in Lake Pontchartrain. _Tangipahoa_: TU 13623, 3.1 mi. +W Hammond; USNM 68054, Robert. _Washington_: KU 50840, 50846, TU 17117, +Pearl River at Varnado. _Parish unknown_ (East Baton Rouge or +Tangipahoa): UMMZ 95614, Manchac. + +MISSISSIPPI: _Chickasaw_: USNM 115981, Chookatonkchie Creek. _Clarke_: +USNM 79350-51, 1 mi. W Melvin, Choctaw County, Alabama; USNM 100805, +Enterprise. _Forrest_: WEB 55-586, 1 mi. S Hattiesburg. _Hancock_: AMNH +46780; WEB 54-651, Hickory Creek "near" Kiln. _Lauderdale_: UMMZ 74681, +9 mi. W Meridian; UMMZ 90130, Lake Juanita, 15 mi. W Meridian. +_Lawrence_: KU 47120, TU 17307.1, Pearl River, 9 mi. S Monticello; USNM +7653-54, Pearl River at Monticello. _Lee_: CM 31904, Verona; USNM +115979, Cower's Area near Guntown. _Madison_: USNM 95191, 95193-94, +Pearl River. _Marion_: MCZ 1597, Pearl River at Columbus (designated +type locality). _Pearl River_: CM 21100, Pearl River, 20 mi. W +Poplarville; TU 14362, Hobolochito Creek, 1 mi. N Picayune. _Perry_: WEB +55-580, Beaver Dam Creek, 1 mi. N Richton. _Walthall_: KU 50844, Bogue +Chitto River, Dillon. + +SOUTH CAROLINA: _Abbeville_: USNM 7650, Abbeville? (reported by Pickens, +1927:113; locality considered in error by Stejneger, 1944:50; USNM 7650 +having only one dark marginal line paralleling rear margin of carapace +is possibly an aberrant specimen--see page 495 of present account). +_Greenwood_: USNM 71681, 73668, Greenwood. _McCormick_: USNM 91310-12, +Savannah River, 5 mi. W Plum Branch; USNM 92521, near Parksville. +_Richland_: AMNH 70724-25, Broad River, Columbia. + +NO DATA: USNM 8359 (erroneously reported from Madison, Indiana by +Yarrow, 1882:29 and Hay, 1892:145; see discussion by Cahn, 1937:200, and +Stejneger, 1944:73-75); USNM 131859. + +_Records in the literature._--ALABAMA: _Coffee_: Elba (KKA). _Marengo_: +Tombigbee River near Demopolis. _Mobile_: Fig Island (Löding, 1922:47). + +FLORIDA: _Jackson_: Chattahoochee River, 8 mi. SE Butler. _Leon_: +Ochlocknee River, NW of Tallahassee (Goin, 1948:304). + +GEORGIA: _Bartow_: Etowah River below Allatoona Dam, _ca._ 4 mi. ESE +Cartersville (Crenshaw and Hopkins, 1955:15). _Berrien_: (Knepton, +1956:324). _Emanuel_: Ogeeche River (Schwartz, 1956:19). _Fulton_: Nancy +Creek, Atlanta (Dunston, 1960:278). _Gwinnett_: _Irwin_: (Knepton, _loc. +cit._). _Jenkins_: Ogeeche River near Buckland Creek jct., 2.5 mi. S +Millen. _Liberty_: Camp Stewart, 4 mi. N Hinesville. _Morgan_: Lake +Rutledge (Schwartz, _loc. cit._). _Muscogee_: Columbus (Stejneger, +1944:52). _Wayne_: Altamaha River, 5 mi. N Mt. Pleasant (Schwartz, _loc. +cit._). _Wilcox_: Ocmulgee River, 3-4 mi. SSE Abbeville (Crenshaw and +Hopkins, _op cit._:16, footnote; Schwartz, _loc. cit._). + +MISSISSIPPI: _George_: Whiskey Creek (Cook, 1946:185). _Harrison_: near +Biloxi. _Jackson_: Pascagoula Swamp, _ca._ 40 mi. E. Biloxi (Corrington, +1927:101). _Jones_: Eastabuchie. _Lee_: Cain Creek Bottom. _Lincoln_: +Old Brook Creek. _Lowndes_: Tombigbee River, Camp Henry Pratt and +Columbus; Lake Park, Columbus. _Pearl River_: 21 mi. SW Poplarville; 10 +mi. W Poplarville; 4 mi. W Poplarville. _Wayne_: Trigg Area (Cook, _loc. +cit._). + +NORTH CAROLINA: _Mecklenburg_: Catawba River near Charlotte (Schwartz, +1956:20). + +SOUTH CAROLINA: _Aiken_: Savannah River, 10 mi. SW Jackson. _Allendale_: +Savannah River, Fennell Hill, 2 mi. S US 301. _Anderson_: Pendleton. +_Bamberg_: South Edisto River, Cannon's Bridge, 5 mi. from Bamberg. +_Berkeley_: 2.5 mi. W Pinopolis. _Charleston_: Charleston. _Clarendon_: +Upper Lake Marion at US 301; Lake Marion, 13 mi. SW Manning; 3.3 mi. S +Jordan; 6.3 mi. S Jordan; Wyboo Creek, 8.5 mi. from Manning. _Colleton_: +Edisto River (Schwartz, 1956:19-20). _Darlington_: Pee Dee River, +Society Hill (Stejneger, 1944:72). _Dorchester_: Edisto River, 17 mi. +from Summerville; Edisto River, 14 mi. W Summerville; Edisto River, 2.5 +mi. S Hart's Bluff. _Fairfield_: 1 mi. N Peak, Newberry County. +_Georgetown_: North Santee River, 1 mi. above US 17. _McCormick_: Little +River near McCormick; Little River, 3 mi. NE Mt. Carmel. _Laurens_: +Enoree River, 3 mi. S Cashville, Spartanburg County; Enoree River, 9.4 +mi. N Clinton. _Orangeburg_: Edisto River, Orangeburg. _Saluda_: +Batesburg; Lake Murray; Little Saluda River; 5 mi. from Saluda. _County +unknown_: Upper Lake Santee (Schwartz, _loc. cit._). + + + +=Trionyx spinifer emoryi= (Agassiz) + +Texas Spiny Softshell + +Plates 43, 44 + + _Aspidonectes emoryi_ Agassiz (in part), Contr. Nat. Hist. United + States, Vol. 1, Pt. 2, p. 407; Vol. 2, Pt. 3, pl. 6, figs. 4-5, + 1857. + + _T[rionyx] s[pinifer] emoryi_ Schwartz, Charleston Mus. Leaflet, + No. 26, p. 11, 1956. + +_Type._--Lectotype, USNM 7855; alcoholic (sex undetermined); obtained +from the Río Grande near Brownsville, Texas, in the course of the +Mexican Boundary Survey under the command of Colonel Wm. H. Emory. + +_Range._--Southwestern United States and northern México; the Río +Grande drainage in Texas, New Mexico and northern México; the Río San +Fernando and Río Purificación drainages in northeastern México; the +Colorado River drainage in Arizona, New Mexico, and southern Nevada +(see map, Fig. 19). + +_Diagnosis._--Juvenal pattern of white dots, not encircled with dusky +or blackish ocelli, confined to posterior third of carapace; pale rim +of carapace conspicuously widened, four to five times wider +posteriorly than laterally; a dark triangle in front of eyes, base +line connecting anterior margins of orbits; pale postocular stripe +interrupted leaving conspicuous pale, usually dark-bordered, blotch +just behind eye. + +_Description._--Plastral length of smallest hatchling, 2.5 centimeters +(USNM 7632); of largest male, 13.0 centimeters (KU 2914, 3125, 3150); +of largest female, 22.0 centimeters (TNHC 8023, 8104). + +Carapace pale brownish or tan, lacking whitish dots on anterior half; +whitish dots confined to posterior third of carapace, sometimes +lacking posteriorly, especially on juveniles; small, blackish dots +rarely occurring on surface of carapace, usually confined to margins +when present; pale rim of carapace four to five times wider +posteriorly than laterally. + +Pattern on snout rarely variable, consisting of pale stripes extending +forward from eyes that have only their outer borders darkened and a +straight or slightly curved, dark line that connects anterior margins +of orbits; few, if any, dark markings in subocular and postlabial +region; pattern on side of head having few contrasting marks, often of +nearly uniform coloration; postocular stripe usually interrupted; +anterior segment of postocular stripe just behind eye usually +dark-bordered; posterior segment usually not dark-bordered or sharply +distinguished from background; pattern on dorsal parts of soft parts +of body contrasting, of relatively small dark marks; dark streaks +often coincident with digits. + +Underparts whitish, occasionally having blackish dots or smudges on +posterior part of carapace, in region of bridge, or on lateral parts +of chin and throat; few dark marks often on webbing of limbs and on +palms and soles. + +Small, flattened or wartlike, tubercles that occasionally have sharp +tips along anterior edge of carapace on adult males; tubercles +flattened, scarcely elevated, never conical along anterior edge of +carapace on large females; whitish, knoblike tubercles often present +posteriorly in middle of carapace and in nuchal region on large +females; mottled and blotched pattern sometimes contrasting on +carapace of large females; whitish dots of juvenal pattern often +visible through overlying blotched pattern of large females. + +Ontogenetic variation in PL/HW, mean PL/HW of specimens having +plastral lengths 7.0 centimeters or less, 3.68, and exceeding 7.0 +centimeters, 5.19; ontogenetic variation in CL/CW, mean CL/CW of +specimens having plastral lengths 8.5 centimeters or less, 1.17, and +exceeding 8.5 centimeters, 1.27; mean CL/PCW, 2.18; mean HW/SL, 1.43; +mean CL/PL, 1.37. + +_Variation._--Ten topotypes (six males, three females, one juvenile) +from Brownsville, Texas (BCB 7465-73, 7564), have the following +characteristics: pale rim widened posteriorly as described above; +females (plastral lengths 9.8, 10.2 and 11.7 cm.) having blackish +marks in pale rim, which are absent in males of corresponding size; +interrupted postocular stripe with pale blotch behind eye; postocular +pale blotch having blackish borders or not; dark triangular mark on +snout in front of eyes; white dots present only on posterior third of +carapace; carapace of females grayish, blotched pattern not +contrasting; carapace of males paler, greenish-gray; undersurface +immaculate except 7468 and 7472 that have blackish flecks at bridge +and, on 7472, blackish marks that extend posteriorly onto ventral +surface of carapace; tubercles along anterior edge of carapace +flattened and rounded in adult males, more knoblike in females; +largest specimen, BCB 7472, female, plastron 11.7 centimeters long. + +_T. s. emoryi_ varies more than any other subspecies of _Trionyx +spinifer_. A large series of males and females (KU) from the Salt +River (Colorado River drainage), near Phoenix, Arizona, is +characterized by many adult males having indistinct white dots on +posterior half of carapace; blotching on carapace of females of +contrasting lichenlike figures, but usually non-contrasting and pale +brownish or tan; pale rim of carapace distinct from ground color of +carapace in largest female (KU 2905, plastron 21.5 cm. in length), but +having dark or dusky markings: dark interorbital stripe often lacking. +AMNH 58370 (Nevada) and UMMZ 92006 (Arizona) also have the dark line +connecting the anterior margins of the orbits interrupted; seemingly +the dark interorbital line is most often interrupted in those +softshells inhabiting the Colorado River system of Nevada and Arizona. + +Other variant individuals are: TU 14453.2, 14462 and 3696 having the +plastron extending slightly farther forward than the carapace, thus +resembling _T. ferox_; UMMZ 54021 and CNHM 39999, hatchlings, lacking +distinct whitish dots on posterior half of carapace; UI 43509 and KU +39991 having stained (brown or blackish) claws; and, CNHM 6810, an +adult male, lacking a spinose (sandpapery) carapace. I am unable to +discern geographic variation in these or other characters. + +The ground color of the carapace on some individuals from the Pecos +River (TU, Terrell County, Texas) is grayish and in contrast with the +pale rim (Pl. 44). UI 43509 from the Río Florida, La Cruz, Chihuahua, +a female, has a dark brownish carapace with little evidence of a +blotched pattern except on the pale rim of the carapace. A female and +adult male from the Río Sabinas, Coahuila (MSU 905-06), also show +considerable darkening on the dorsal surfaces; the pale rim is evident +but not in sharp contrast to the coloration of the carapace. Notes +taken on the freshly-killed Sabinas individuals are: male--carapace +olive-gray; dorsal surface of soft parts of body olive-green to +grayish, a bright yellow suffusion on limbs and neck; female--carapace +and soft parts of body dark olive, laterally pale yellow; the plastron +extends slightly farther forward than the carapace in both sexes. + +Notes on coloration (judged to be the most common or "normal" type) +of living _emoryi_ from the Río Mesquites, central Coahuila, are: +Adult male (KU 53753)--pale rim butterscotch yellow; marginal line +blackish; whitish dots on pale brown or tan carapace; soft parts of +body olive or olive-green, slightly darker on head and paler +(yellowish) on hind limbs; pale areas on side of head pale yellow, +having tint of orange on neck; ventral surface white, yellow laterally +on neck. Adult female (KU 53754)--carapace having contrasting blotched +and mottled pattern of pale browns and tans; soft parts of body olive +brown, darker brown blotching on head; dorsal surface of limbs +olive-green having pale areas lemon yellow and webbing butterscotch +yellow; side of neck and head, chin and throat pale lemon yellow; +ventral surface white having slight red tinge to groin and soft parts +posteriorly; underside of carapace near edge pale yellow. + +Softshells from the Río Grande in the Big Bend region of Texas, and +the Río Conchos in Chihuahua differ from other specimens of _emoryi_. +Fifteen adult males, KU 51187-201 (no females in sample), were taken +from the mouth of the Río San Pedro at Meoquí, Chihuahua (see KU +51194, Pl. 44). They are noteworthy because of a conspicuous orange or +orange-yellow on the side of the head. Another relatively consistent +character is the blackish tip of snout (excepting 51199), although the +degree (palest on 51190) and extent of pigmentation posteriorly on the +snout is variable. Eleven males, KU 51175-85, from approximately 100 +miles northeastward in the Río Conchos near Ojinaga, Chihuahua, also +have the bright orange on the side of the head; the tip of the snout +is not blackish, although in some it is slightly darkened. Three +females, KU 51174, 51186 (from Ojinaga) and 51173 (from 8 mi. S, 16 +mi. W Ojinaga), lack the orange on the side of the head; KU 51186 has +a plastral length of 8.0 centimeters, whereas the other two females +have the same plastral length of 16.5 centimeters (larger than any +male). Nineteen adult males, KU 51965-72, 51980-90, from the Río +Grande near Lajitas also have the orangish coloration on the side of +the head, whereas twenty females, KU 51954-64, 51973-79, 51991-92 +(three smaller than largest male) lack the coloration. The tip of the +snout is not blackish on any turtle in the series from Lajitas. The +smallest female, from Lajitas, having a plastral length of 6.9 +centimeters, has a mottled carapace. + +The orange of males is most conspicuous in the pale postocular and +postlabial areas; the stripes of the snout (distally) and the color of +the neck at its juncture with the immaculate ventral surface are +orange-yellow. The orange coloration is confined to males (all +examined were sexually mature) and is probably not of seasonal +occurrence (see comments under secondary sexual variation). I have not +noticed this coloration in other males of the subspecies _emoryi_; +however, long-preserved males might be expected to lack the orange +color; the specimens mentioned above were initially preserved in +alcohol. KU 51179 (plastral length 8.2 cm., from Ojinaga) is the +smallest sexually mature male of the species _spinifer_ that I have +seen. Another character of note is the generally greater development +of the plastral callosities (resembling _muticus_) than in other +subspecies of _spinifer_ or specimens of _emoryi_; three small adult +males (KU 51177, 51990, 51987, plastral length 9.3, 9.9 and 9.1 cm., +respectively) have large hyoplastral and hypoplastral callosities that +appear to touch medially, and callosities on the epiplastron and both +preplastra. + +On July 8, 1953, an adult male of _T. spinifer_ was removed from a +hoop-net set in the Río Purificación at Padilla, Tamaulipas, México. I +was particularly impressed by the lack of whitish dots on the dark +carapace; the following notes were taken from the freshly-killed +specimen: carapace a uniform dark olive, lacking white dots and having +a yellowish rim widest posteriorly; tubercles on anterior edge of +carapace only slightly raised, inconspicuous; top of head olive with +few dots and streaks; a well-defined yellowish postocular stripe not +conspicuously interrupted; sharp contrast between dark olive on side +of head and pale ventral coloration; yellowish-orange ventrolaterally +on head; an uninterrupted slightly-curved line connecting the anterior +margins of the orbits; carapace pear-shaped; underparts whitish, +lacking markings. This specimen has since been destroyed. The only +other specimen I have seen from this locality is a hatchling (UMMZ +69412, Pl. 43), which has a pale brownish or tan carapace that lacks +whitish dots; it resembles _emoryi_ in other characters. Although the +absence of whitish dots is not distinctive, its combination with the +uniform dark olive carapace in adult males and the fact that the Río +Purificación is an isolated drainage system, suggests that +soft-shelled turtles from that river system may warrant further +taxonomic study. + +_Comparisons._--From all other subspecies of _spinifer_, _T. s. +emoryi_ can be distinguished by having a pale rim on the carapace that +is four to five times wider posteriorly than it is laterally. This +character, unique for _emoryi_, combined with patterns on the snout, +side of head and carapace that are subject to little variation, permit +ready identification of the subspecies _emoryi_. _T. s. emoryi_ +resembles _pallidus_, and _guadalupensis_ and differs from _spinifer_, +_hartwegi_ and _asper_ in having whitish tubercles or dots on the +carapace. _T. s. emoryi_ resembles _guadalupensis_ but differs from +_pallidus_, _spinifer_, _hartwegi_ and _asper_ in lacking conical +tubercles along the anterior edge of the carapace on large females. +For additional differences see accounts of other subspecies. + +Some populations of _T. s. emoryi_ resemble _T. muticus_ in the size +at which sexual maturity is attained and in the development of the +plastral callosities. _T. s. emoryi_ has a wide head that resembles +that of _T. ferox_, _T. ater_, _T. s. asper_ and _T. s. +guadalupensis_; _T. s. emoryi_ also resembles _T. ferox_ and _T. ater_ +but differs from the other subspecies of _T. spinifer_ and _T. +muticus_ in having a narrower carapace. _T. s. emoryi_ resembles _T. +s. guadalupensis_, _T. s. pallidus_ and _T. ater_, and differs from +the other subspecies of _spinifer_ and _T. muticus_, in having the +carapace widest farther posteriorly than one-half way back on the +carapace. _T. s. emoryi_ resembles _T. ferox_ in having the shortest +length of snout of the subspecies of _spinifer_. The plastron is +shorter than in _T. ferox_, longer than in _T. s. asper_, and about +the same length as in _T. muticus_ and the other subspecies of _T. +spinifer_. + +_Remarks._--Agassiz (1857, 1:407-08) did not designate a holotype in +the original description of _Aspidonectes emoryi_; specimens are +mentioned from the lower Río Grande of Texas, near Brownsville, and a +stream of the Río Brazos drainage in Williamson County, Texas. The +description is applicable to _T. s. emoryi_ as herein restricted, +except for the statement that the white tubercles of young specimens +are "encircled by faint black lines"; that statement is presumably +based on the juveniles from Williamson County. _T. s. emoryi_ does not +occur in Williamson County, Texas. Barbour and Loveridge (1929:225) +listed MCZ 1909-10 and 1627 as cotypes. Stejneger (1944:65) mentioned +MCZ 1909, 1913 and USNM 7855 as cotypes; the legend for Plate 20 (_op. +cit._) refers to a drawing that "corresponds fairly closely with the +type (MCZ 1910) collected at Brownsville, Texas, by Col. Emory." + +The syntypic series consists of seven specimens--MCZ 1627 (two +specimens) from Williamson County, Texas; MCZ 1909 (three specimens) +and 1910 from Brownsville, Texas; and USNM 7855 from Brownsville, +Texas. The listing of number 1913 by Stejneger is considered a +_lapsus_ for 1910 as MCZ 1913 is catalogued as a _Graptemys +geographica_ (in letter dated November 17, 1959 from Dr. Ernest E. +Williams). Stejneger's reference to MCZ 1910 as the type is considered +unintentional and an inadequate designation of a lectotype. + +In the "remarks" column of the USNM museum catalog, number 7855 is +referred to as "Ag. Type." USNM 7855 is here designated as lectotype +of _Trionyx spinifer emoryi_. The lectotype is a young specimen +(female?) that is not easily sexed by external characters; the +plastron measures (in centimeters) 6.3 in length, the carapace 8.2 in +length and 7.0 in width, and the head 1.4 in width. The carapace is +pale brown having inconspicuous whitish dots posteriorly and a pale +rim that is approximately 6.8 times wider posteriorly (4.1 mm.) than +it is laterally (0.6 mm.). The slightly curved dark line connecting +the anterior margins of the orbits is dimmer than the dark lines that +extend forward from the eyes. The pale postocular stripes having +blackish, dotted borders are interrupted; there are no other markings +on the side of the head. The ventral surface is immaculate except for +a few dark dots on the right side of the carapace; the ground color is +pale brown or tan, but the upper layer of skin can be scraped away +revealing an underlying pale lavender-cream ground color. The +tubercles along the anterior edge of the carapace resemble small +rounded warts. + +MCZ 1910 is an adult male _T. s. emoryi_ having a plastron 10.7 +centimeters in length. The carapace is pale brown having a relatively +smooth anterior edge, inconspicuous whitish tubercles posteriorly, and +a pale rim five times wider posteriorly than laterally; the pattern on +the head resembles that of _emoryi_. + +Each of three hatchlings of _T. s. emoryi_, 3.4, 3.5 and 3.9 +centimeters in plastral length, bears an MCZ catalogue number of 1909. +The carapaces are dark tan or gray having pale rims 3.7, 5.2 and 5.2 +times wider posteriorly than laterally, and white dots absent or +obscure posteriorly; two specimens have small blackish dots +paralleling the pale rim posteriorly. The patterns on the heads are +referable to _emoryi_. + +The two juvenal syntypes (5.2 and 6.1 cm. in plastral length) from +Williamson County, Texas, are both catalogued as MCZ 1627, but only +one of these bears a catalogue number. The two softshells are not +_emoryi_, and are more nearly like _T. s. guadalupensis_ than _T. s. +pallidus_. Actually, they are from an area of intergradation between +those subspecies (see comments concerning intergradation under the +accounts of the subspecies _pallidus_ and _guadalupensis_). White +spots occur on the carapaces anteriorly and posteriorly, the larger +(more posterior) of which are encircled with dusky ocelli. The +carapace of the small specimen (bearing no number) is brown having a +few, small black specks intermixed with the white spots. The carapace +of the large specimen is pale lavender and has a more obscure pattern +than the other specimen. + +After Agassiz's description, _emoryi_ was accepted as a distinct +species. Neill (1951:15) suggested that _emoryi_ was subspecifically +related to _T. ferox_. Crenshaw and Hopkins (1955) and Schwartz +(1956), however, demonstrated that _ferox_ was a distinct species; +_emoryi_ has since been considered a subspecies of _T. spinifer_. + +Two specimens having blackish dots on the carapace, indicate +relationship with _T. s. guadalupensis_. USNM 7638, a hatchling, has +large whitish dots surrounded by blackish dots confined to the +posterior half of the carapace, and the locality for this specimen is +merely Río Bravo (= Río Grande). CNHM 47366, a hatchling from Sierra +de las Palmas (Sierra de Santa Rosa, La Palma), Coahuila, has a few, +small, blackish dots, irregularly spaced, on the anterior half of the +carapace, but other dots more evenly distributed on the posterior half +where they are intermixed with whitish dots. The drawing of the dorsal +view of a hatchling _emoryi_ (Agassiz, 1857:Pl. 6, Fig. 4) shows a +sprinkling of blackish dots on the anterior half of the carapace. A +hatchling from Eagle Pass (USNM 116578) does not have a noticeably +widened pale rim posteriorly on the carapace, and is not +distinguishable from _pallidus_. See account of _T. s. guadalupensis_ +for further comments on intergradation. + +A soft-shelled turtle that was obtained in the Sacramento River by +three fishermen, near Sacramento, California, was named _Aspidonectes +californiana_ by Rivers (1889:233). A comparison (with _Aspidonectes +spinifer_ and _A. emoryi_) of certain features of the skull was +largely prepared by Baur and included in the description (_op. +cit._:234-35); seemingly, the most trenchant character of the skull of +_californiana_ was the enlarged alveolar surfaces of the jaws. This +feature prompted Baur (1893:220) to refer _californiana_ to the genus +_Pelodiscus_, which also included _agassizi_ (skulls also having jaws +with enlarged alveolar surfaces) and several Old World species. Van +Denburgh (1917) discussed the origin of the specimen that formed the +basis of River's description and concluded that it was brought over +from China. Siebenrock (1924:192) and Mertens and Wermuth (1955:389) +listed _Aspidonectes californiana_ as a synonym of _emoryi_. River's +description is not that of _emoryi_; the enlarged alveolar surfaces of +the jaws, and the dark carapace having tubercular ridges suggest a +resemblance to _T. ferox_. The papillae on the neck are not found in +any American species. Miller (1946:46, footnote 2) believed that "it +obviously was introduced, apparently from China," and cited Pope +(1935:61), who declared the specimen to represent _Trionyx sinensis_. + +Schmidt (1924:64) first reported the occurrence of _T. s. emoryi_ west +of the continental divide in Arizona and suggested that it was highly +probable that the species had been introduced near Phoenix in recent +years. Cowles and Bogert (1936:42) mentioned a species of softshell +occurring in the Boulder Dam region and presumed the species to be +native to Asia and introduced by the Chinese. Linsdale and Gressitt +(1937:222) determined the status of the species in the Colorado River +drainage as _T. s. emoryi_. The discussions by Dill (1944:179-81) and +Miller (1946:46) indicate that _emoryi_ was introduced into the Gila +River (Colorado River drainage) in western New Mexico near the turn of +the century. + +_T. s. emoryi_ and _T. ater_ are the only kinds of softshells +occurring in México. The colloquial name for soft-shelled turtles in +México is "tortuga blanca." This name is also used in reference to the +Central American river turtle, _Dermatemys mawei_, which occurs on the +east coast of México as far north as Veracruz. + +_Specimens examined._--Total 275, as follows: ARIZONA: _Maricopa_: +CNHM 4768, KU 2214-19, 2803, 2824, 2837, 2903-07, 2909-16 (2914, 2 +specimens), 2918-29, 3118-27, 3129, 3147-56, USNM 71627, Salt River, +Phoenix. _Pinal_: UI 37713, Gila River, 6 mi. E Winkleman; UMMZ +92006-07, Gila River, 1/2 mi. below Coolidge Dam; UMMZ 105824, San +Pedro River about 1 mi. above confluence with Gila River. + +NEVADA: _Clark_: AMNH 58370, Boulder City boat landing, Lake Mead; TU +15802, Virgin River, Mesquite. + +NEW MEXICO: _Eddy_: KU 15938, Carlsbad; KU 48217-18, Black River +Village. _Grant_: AMNH 79911, Gila River, 8 mi. NE Cliff. + +TEXAS: _Brewster_: CNHM 39999, Tornillo Creek near jct. with Río +Grande; KU 51954-92, Lajitas; TCWC 4291, UMMZ 66471, USNM 45545, +103678, Boquillas; INHS 7975, UMMZ 114360, Hot Springs. _Cameron_: BCB +7564-73, CNHM 5339-40, 6810, MCZ 1909 (3), 1910, TU 11479-80, +11561-62, UMMZ 54021, 105209-13 (Brownsville Lake), USNM 7642, 7644, +7855, Brownsville; BCB 5121, 3 mi. S Harlington. _El Paso_: UMMZ +85085, El Paso; USNM 7641, 7701, El Paso del Norte. _Hudspeth_: USNM +20846, Fort Hancock on Río Grande. _Kinney_: CNHM 26090, Río Pinto W +of Bracketville; USNM 26426-36, Fort Clark. _Loving_: TTC 1143, Red +Bluff Lake just below dam on Pecos River. _Maverick_: TU 3696-97, UMMZ +116578, Eagle Pass. _Presidio_: TTC 628 (2), 632 (2), 3 mi. WNW +Lajitas, Brewster County. _Terrell_: TNHC 7997, 8022-23, Chandler +Ranch, 30 mi. S Sheffield, Pecos County; TNHC 8104, Dunlap Ranch, 25 +mi. SE Sheffield, Pecos County; TU 14453 (7), 14462 (2), 15415, 15423, +15586, Pecos River near jct. with Independence Creek; USNM 104240, +Pecos River "near" Dryden. _Val Verde_: TTC 113, Pecos River. _Webb_: +TNHC 19788, 42 mi. NW Laredo; USNM 109078-79, Laredo. _Zapata_: UI +19332, "near" Zapata. _County unknown_: MCZ 1628, USNM 7635-36, 7854; +USNM 7637-38, Río Bravo (= Río Grande). + +CHIHUAHUA: KU 51173, 8 mi. S, 16 mi. W Ojinaga; KU 51174-86, 1 mi. NW +Ojinaga; KU 51187-201, Río Conchos at mouth of Río San Pedro near +Meoquí; UI 43508-09, Río Florida, La Cruz. + +COAHUILA: CNHM 26054, Sta. Helena Canyon of Río Grande; CNHM 28846, +"near" Músquis; CNHM 55657, Río Alamos, Rcho. de la Gacha; CNHM 47366, +Sierra de Santa Rosa, La Palma; CNHM 47367, 55661, Cuatro Ciénegas; +CNHM 55658-60, Rcho. de los Borregos near Juarez; KU 33523, La Presa +Don Martín; KU 39991, 39993, 8 mi. N, 2 mi. W Piedras Negras; KU +39992, 2 mi. W Jiménez; KU 46907, 16 km. S Cuatro Ciénegas; KU +46913-16, 10 km. S Cuatro Ciénegas; KU 53752-54, Río Mesquites, 8 mi. +W Nadadores; KU 53757, 8.5 mi. SW Cuatro Ciénegas; MSU 905-06, Río +Sabinas, 1 mi. E Sabinas. + +NUEVO LEON: CNHM 1874, 2191, Rodriguez; UMMZ 69411, Río Conchos, 9 mi. +N Linares. + +TAMAULIPAS: CM 3037, Nuevo Laredo. UMMZ 7614-20, 7622-25, 7628, 7630, +7632-33, Matamoros; UMMZ 69412, Río Purificación, N of Ciudad +Victoria. + +NO DATA: MCZ 1629 (2), NHB 1032. + +_Records in the literature._--ARIZONA: _Greenlee_: Gila River, Duncan +(Miller, 1946:46); "near" Sheldon (Dill, 1944:180). _Mohave_: Pierce's +Ferry just below lower end of Grand Canyon (Cowles and Bogert, +1936:42); 1.5 mi. upstream (Virgin River) from Mesquite, Clarke +County, Nevada (Hardy and Lamoreaux, 1945:168); Lake Havasu on +Colorado River (Dill, 1944:180). _Yuma_: Colorado River at Headgate +Rock Dam (Dill, _op. cit._:179). + +CALIFORNIA: _Imperial_: California Lakes (Cowles and Bogert, 1936:42); +Palo Verde; Colorado River at Laguna Dam (Dill, 1944:180). + +NEVADA: _Clark_: observed just north of Black Canyon (Cowles and +Bogert, _loc. cit._); Colorado River, 6 mi. N California line +(Linsdale, 1940:255). + +NEW MEXICO: _Chaves_: Bitter Lakes Wildlife Refuge, 12 mi. NE Roswell +(Bundy, 1951:314). _Dona Ana_: Río Grande near Mesilla Dam (Little and +Keller, 1937:221). + +TEXAS: _Brewster_: Río Grande at Castolon (Minton, 1959:38). _Val +Verde_: mouth of Devil's River (Brown, 1950:250). + +BAJA CALIFORNIA: Colorado River delta, 7 mi. E Cerro Prieto; Imperial +Irrigation District, Alamo Canal, 15 mi. S Internat'l Boundary and +Salfatana Canal, 1 mi. N Black Butte (Linsdale and Gressitt, +1937:222). + +COAHUILA: San Juan (Schmidt and Owens, 1944:103). + +Hitherto, soft-shelled turtles of the species _Trionyx spinifer_ from +the southern and southwestern United States having a pattern of white +dots on the carapace have been relegated to the subspecies _emoryi_, +but my examination of soft-shelled turtles from Texas has indicated +that _T. s. emoryi_ as previously conceived, is a composite of three +subspecies. It is necessary, therefore, to recognize two new +subspecies. + + +=Trionyx spinifer guadalupensis= new subspecies + +Guadalupe Spiny Softshell + +Plates 41 and 42 + +_Holotype._--UMMZ 89926, alcoholic adult male; obtained 15 miles +northeast Tilden, McMullen County, Texas (Pl. 41, bottom, left). + +_Paratypes._--Forty-two specimens: ANSP 16717 (hatchling), no data; +USNM 78515-16 (hatchlings), Colleto Creek, Victoria County, Texas; TU +10143-45, 10148, 10150-59, 10161-65 (adult males), TU 10176, 10833 +(immature males), TU 10147, 10149, 10155 (immature females), TU 10160 +(adult female), Guadalupe River, 9 miles southeast Kerrville, Kerr +County, Texas; UMMZ 89915-21, 89924-27 (adult males), UMMZ 89922-23 +(immature females), same locality as holotype; UMMZ 92752 (immature +female), San Antonio River, 3 miles west-northwest Goliad, Victoria +County, Texas. + +_Description of holotype._--Carapace nearly circular, widest at level +of posterior border of hypoplastra; margin entire; dorsal surface +"sandpapery" to touch; pale rim separated from ground color of +carapace by well-defined, blackish line that is wavy and narrowly +interrupted posteriorly and anteriorly; pale rim approximately 1.8 +times wider posteriorly (5.4 mm.) than laterally (3.0 mm.); pale rim +increasingly narrower anteriorly, absent in nuchal region; tubercles +in nuchal region low, scarcely elevated, lacking sharp tips; ground +color of carapace olive having pattern of whitish spots and small +tubercles; most whitish tubercles inconspicuous pinpoints; other small +tubercles in center of whitish spots, mostly approximately 2 +millimeters in diameter; largest white spot 3.4 millimeters in +diameter; most white spots surrounded by blackish ocelli or parts +thereof; whitish spots distributed over entire surface of carapace; +certain features of bony carapace evident through overlying skin; +carapace highest in region of second and third neurals, forming +obtuse, gently sloping, vertebral, keel; undersurface of carapace +butterscotch yellow, lacking markings; maximum length, 16.5 +centimeters; greatest width, 13.5 centimeters. + +Plastral surface butterscotch yellow, lacking markings, extending +slightly farther forward than carapace; anterior and posterior lobes +rounded; anterior lobe slightly truncate; certain features of bony +elements of plastron visible through overlying skin; maximum length of +plastron, 12.0 centimeters. + +Head, extended to posterior level of eyes, terminating in flexible +snout; septal ridges projecting into each rounded nostril; jaws +closed, each covered by fleshy lips except anteriorly where horny +portions exposed; dark triangular mark in front of eyes, base line +connecting anterior margins of orbits forming series of dots; pale +stripes extending forward from eyes having faint inner, blackish +borders; eyelids partly open having blackish dots; pale subocular +blotch on right side of head having border of black dots. + +Forefeet and hind feet well-webbed having five digits each; each limb +having nails on first three digits; each forelimb with four +antebrachial scales, three of these having free edge; each hind limb +with two horny scales, one smooth on posterodorsal surface and other +with free edge on posteroventral surface; pattern toward insertion of +forelimbs indistinct. + +Tail terminating in flexible point; penis exposed; cloacal opening +extending beyond posterior edge of carapace; tail olive above bordered +by blackish marks; few black dots laterally on left side. + +Undersurface of soft parts of body buff, lacking markings; few dark +marks posteriorly on webbing of limbs, encroaching on soles and palms. + +_Range._--Southcentral Texas in the drainage systems of the Nueces and +Guadalupe-San Antonio rivers; the Colorado River drainage in Texas is +inhabited by a population that more closely resembles _guadalupensis_ +than _pallidus_. See comments under subsection entitled "Remarks" and +Fig. 19. + +_Diagnosis._--Juvenal pattern of white dots that are conspicuous on +anterior half of carapace, and usually as large as those on posterior +half; white dots, sometimes 3 millimeters in diameter, encircled with +blackish ocelli in adult males. + +_Description._--Plastral length of smallest hatchling, 3.3 centimeters +(ANSP 16717); of largest male, 13.5 centimeters (TU 10162); of largest +female, 22.0 centimeters (TU 10160). + +Hatchlings having white dots on anterior half of carapace; white dots +anteriorly nearly as large as those posteriorly, encircled with +blackish ocelli, and conspicuous on dark background (ANSP 16717, Pl. +41; USNM 78515-16; Stebbins, 1954:181, Pl. 26B), or smaller than those +posteriorly, not encircled with dusky ocelli, and inconspicuous on +pale background (TNHC 1446); pale rim of carapace less than four times +as wide posteriorly as laterally. + +Adult males resembling holotype; size of white tubercles on carapace +variable; most, if not all, tubercles surrounded by narrow blackish +ocelli, or parts thereof; largest white tubercles or dots in most +specimens exceeding one millimeter and in some specimens three +millimeters in diameter (TU 10163); white dots often slightly elongate +(UMMZ 89917, 89920, 89926; TU 10152, 10145); juvenal pattern of white +dots seemingly more contrasting in _guadalupensis_, owing to dark +ground color of carapace, than in _pallidus_ or _emoryi_ that have +pale brown or tan carapaces; small tubercles along anterior edge of +carapace rounded, obtuse, wartlike, never conical; sharp tips often +lacking (TU 10153). + +Large females often having whitish spots on anterior half of carapace +(TU 10160, Pl. 42, upper, right; 10142); carapace dark having +ill-defined mottled and blotched pattern; tubercles along anterior +edge of carapace low, rounded, rarely equilateral, never conical; +small blackish dots rarely on surface of carapace (UMMZ 89923). + +Pattern on side of head and snout of little diagnostic value; +postocular stripe usually interrupted, but configuration variable, +consisting of pale anterior, dark-bordered segment (just behind eye); +posterior segment of postocular stripe usually less well-defined and +generally blending with adjacent ground color; pale postocular stripe +sometimes uninterrupted and dark-bordered throughout its length (TU +10157, 10159, 10176); pattern on dorsal surface of snout variable; +pattern usually consisting of uninterrupted dark line (slightly curved +anteriorly) connecting anterior margins of orbits (TU 10161, 10164, +10159, 10143), or dark line interrupted (TU 10153, 10154, 10176), +absent (TU 10163), or present in addition to dark inner borders of +pale stripes that extend anteriorly from eyes (TU 10149, 10162); +small, often fine, dark markings, on dorsal surface of limbs, +especially forelimbs; ventral surface of plastron and soft parts of +body usually whitish, lacking markings; small blackish spots +occasionally in region of bridge (TU 10149); dark marks occurring on +webbing of limbs and often encroaching on soles and palms. + +Ontogenetic variation in PL/HW, mean PL/HW of specimens having +plastral lengths 7.0 centimeters or less, 3.83, and exceeding 7.0 +centimeters, 5.18; ontogenetic variation in CL/CW, mean CL/CW of +specimens having plastron lengths 8.5 centimeters or less, 1.14, and +exceeding 8.5 centimeters, 1.22; mean CL/PCW, 2.11; mean HW/SL, 1.38 +(including subspecies _pallidus_); mean CL/PL, 1.37. + +_Variation._--Two hatchlings (ANSP 13447, Bexar County; TNHC 1446, +McMullen County) more closely resemble _pallidus_ than +_guadalupensis_. + +Some individuals from the Colorado River drainage have features +suggesting those that are characteristic of _pallidus_. Large females +have obtuse, knoblike somewhat triangular-shaped tubercles along the +anterior edge of the carapace, which are never conelike (TU 14439-40, +10187, 16036.1; BCB 6010). The tubercles along the anterior edge of +the carapace are more elevated than in turtles from drainage systems +west of the Colorado. Whitish spots are usually absent anteriorly on +the carapace, but may be evident through the mottled pattern of large +females (BCB 6010, plastral length, 19.7 cm.). The pale postocular +stripe is usually interrupted, whereas the dark line connecting the +anterior margins of the orbits is usually not interrupted; the two +characters last mentioned show alliance with _guadalupensis_. + +The carapace of hatchlings from the Colorado River is pale having +whitish dots, smaller anteriorly than posteriorly, which may be +encircled with dusky ocelli (TNHC 20257) or not (ANSP 11889, BCB 5055, +SM 3282). Many hatchlings are not distinguishable from _pallidus_ +(TCWC 7262, TNHC 4975, SM 4924, 6106). I have not seen hatchlings from +the Colorado River that resemble ANSP 16717. + +The pattern on the carapace of adult males from the Colorado River +drainage resembles that of _guadalupensis_ (Pl. 41, bottom, right) but +the whitish dots are usually smaller and may not be encircled with +blackish ocelli (BCB 4066, TU 14485). An adult male (TU 14476) from +the South Fork of the Llano River has whitish dots three millimeters +in diameter and encircled with blackish ocelli (_guadalupensis_), +whereas another adult male (USNM 83690) from a tributary of the +Colorado, the South Concho River, resembles _pallidus_. + +Eight specimens from the San Saba River (TU 14419 [6 specimens], +14439-40), that range in plastral length from 6.8 to 17.0 centimeters +are impressive because of the dark brownish coloration on the +carapace. The smallest individual, which is also the only male in the +series, is paler. The mottled and blotched pattern on the females is +therefore not contrasting; the largest females have elevated whitish +prominences in the center of the carapace posteriorly. An immature +male (UMMZ 70348) from the South Concho River also has a dark brown +carapace, and lacks white dots. The dark coloration of the carapace of +these specimens recalls the TU series of _T. s. emoryi_ from the Pecos +River, Terrell County, Texas. + +Color notes taken from a freshly-killed adult female from the Llano +River, two miles west Llano (TU 16036.1, Pl. 42), are: pattern on +carapace of dark olive or blackish marks that form an irregular +reticulum or marbling on a paler background that varies from brownish +to buff and has an orange or reddish tinge in some areas; small +whitish spots posteriorly; pale rim yellowish, evident only at sides +of carapace; dorsal surface of soft parts of body olive-green, +becoming paler with yellowish tinge toward insertions of limbs and +neck; no contrasting pattern on limbs or neck and head; yellowish on +sides of body; ventral surface whitish lacking dark marks, yellowish +at region of bridge, axillary region and on neck; chin olive-yellow. + +_Comparisons._--_T. s. guadalupensis_ can be distinguished from all +other subspecies of _T. spinifer_ in having: (1) large white dots, +sometimes three millimeters in diameter, on a dark background usually +surrounded with blackish ocelli and conspicuous on the anterior half +of the carapace (some as large as those on posterior half) in adult +males, and (2) whitish dots on the anterior half of the carapace, in +hatchlings, that are often encircled with dark ocelli. _T. s. +guadalupensis_ resembles _pallidus_ and _emoryi_ in having white +tubercles or dots on the carapace and therein differs from _spinifer_, +_hartwegi_ and _asper_. _T. s. guadalupensis_ resembles _pallidus_ but +differs from _emoryi_ in having a pale rim that is less than four +times wider posteriorly than laterally. _T. s. guadalupensis_ +resembles _emoryi_ but differs from _pallidus_, _spinifer_, _hartwegi_ +and _asper_ in having along the anterior edge of the carapace +tubercles that are flattened or wartlike prominences often lacking +sharp tips in adult males; these tubercles are never conical in large +females. + +_T. s. guadalupensis_ has a wide head, a feature shared with the +subspecies _asper_ and _emoryi_, but differs from _emoryi_ in having a +wider carapace. _T. s. guadalupensis_ resembles _emoryi_ and +_pallidus_ but differs from the other subspecies in having the +carapace widest farther posterior than one-half the length of the +carapace. The length of snout in _pallidus_ and _guadalupensis_ is +shorter than in _spinifer_ and _hartwegi_ but is longer than in +_emoryi_. _T. s. guadalupensis_ differs from _asper_ but resembles the +other subspecies in having a relatively long plastron. + +_Remarks._--Some individuals of _guadalupensis_ have characteristics +that are applicable to _emoryi_. TNHC 12352 (Llano River) a hatchling, +has conspicuous white dots confined to the posterior third of the +carapace; the pale rim, however, is not widened posteriorly. TU 10156 +(Guadalupe River) has a conspicuously widened pale rim on the carapace +that is approximately 3.4 times wider posteriorly (8.5 mm.) than +laterally (2.5 mm.). + +_T. s. guadalupensis_ more closely resembles _pallidus_ than _emoryi_. +Turtles living in rivers that drain into the Gulf of Mexico east of +the Guadalupe-San Antonio river system successively show increasing +resemblance to _pallidus_ from west to east. + +The expression of intergradation between _guadalupensis_ and +_pallidus_ is of a clinal nature that involves parallel changes in the +pattern on the snout, side of head, limbs (to a lesser degree), +tuberculation along the anterior edge of the carapace, size of whitish +tubercles or dots, and the distinctness of the blackish ocelli that +surround the whitish dots on the carapace. These characters form a +well-marked gradation or cline that extends over a considerable area. +There is, however, no continuous environmental gradient because the +populations are relatively isolated by occupying adjacent drainage +systems. The sharpest break in the gradation of characters mentioned +above occurs between the Colorado River and Brazos River drainages. +The population of softshells in the Colorado River drainage is +actually an intergradient one, but more closely resembles +_guadalupensis_, whereas the population in the Brazos River drainage +more closely resembles _pallidus_. For convenience the turtles +inhabiting the Colorado River drainage are referred to _guadalupensis_ +and those in the Brazos River drainage to _pallidus_. Some individuals +from farther west than the Colorado River drainage will resemble +_pallidus_, and a few individuals from father east than the Brazos +River drainage will resemble _guadalupensis_. + +The gradation of some of the characters mentioned above terminates in +the subspecies _emoryi_. It, however, has characters not found in +_pallidus_ or _guadalupensis_, and is more distinct from either of +those subspecies than either is from each other; the difference in +characters as well as the break in the gradient of characters between +_guadalupensis_ in the Nueces River drainage and _emoryi_ in the Río +Grande drainage is greater than that between _guadalupensis_ in the +Colorado and _pallidus_ in the Brazos River drainages. + +I have refrained from designating individuals between these three +subspecies (_emoryi_, _guadalupensis_ and _pallidus_) as "intergrades" +on the distribution maps, and only mention (in text) those individuals +whose characters show a decided tendency toward the adjacent +subspecies. For further comments on intergradation see the account of +_T. s. pallidus_. + +_Specimens examined._--Total 97, as follows: TEXAS: _Bandera_: KU +50834, Hondo Creek, 4 mi. W Bandera; TNHC 797-98, 7 mi. SW Medina. +_Bexar_: ANSP 13447, Helotes; MCZ 4587; USNM 10789, 71009, San +Antonio. _Borden_: BCB 4066, 7 mi. N Vincent. _Brown_: TNHC 7262, 1 +mi. E Brownwood. _Comal_: USNM 7700, New Braunfels. _Dawson_: TNHC +21594-95, 10 mi. E Lamesa. _Frio_: USNM 7747, Río Seco. _Gillespie_: +TU 10185, 10187, 10205, Beaver Creek, "near" Doss. _Hays_: AMNH +29950-52, San Marcos. _Kerr_: SM 2553, headwaters Turtle Creek; TU +10142-45, 10147-65, 10176, 10833, Guadalupe River, 9 mi. SE Kerrville. +_Kimble_: BCB 5052-55, 6010, 3 mi. SE Telegraph; TU 14476, South Fork +Llano River, 1.5 mi. SE Telegraph; TU 14485, Llano River, 10 mi. W +Junction. _Lavaca_: SM 2554-55, 2559, 3 mi. NNE Hope. _Llano_: TNHC +12352, TU 16036 (2), Llano River, 2 mi. W Llano. _McMullen_: TNHC +1446, 10 mi. W Simmons, Live Oak County; UMMZ 89915-27, 15 mi. NE +Tilden. _Matagorda_: ANSP 11889, Matagorda. _San Saba_: SM 6106; TU +14419 (6), 14439-40, San Saba River, 11 mi. NNW San Saba. _Tom Green_: +SM 3282, UMMZ 70348, USNM 83690, South Concho River at Christoval. +_Travis_: SM 659-60, 8.5 mi. from mouth of Onion Creek in Colorado +River near Austin; SM 4924, Onion Creek; TNHC 4975, Upper Bull Creek; +TNHC 20257, Marshall Ford Dam. _Victoria_: CM 3118, Black Bayou; UMMZ +92752, San Antonio River, 3 mi. WSW Goliad; USNM 78515-17, Colleto +Creek, Guadalupe River. _County unknown_: ANSP 16717; TNHC 1404. + +_Records in the literature._--TEXAS: _Bandera_: 24 mi. WNW Medina +(Brown, 1950:250). _Burnet_: Colorado River (Strecker, 1909:8). +_Gillespie_: 20 mi. N Harper (Brown, _loc. cit._). _Kendall_: Cibolo +Creek at Boerne (Strecker, 1926:8). _Kerr_: Guadalupe River, 3 mi. +above Kerrville (TCWC 474, listed in card file). _Mason_: 12 mi. NE +Mason (TCWC 3303, listed in card file). _Matagorda_: Bay City (Brown, +_loc. cit._). _Real_: (Stejneger, 1944:66). _Wilson_: Cibolo River, 30 +or 40 mi. N Sutherland Springs (Strecker, 1935:23). + + +=Trionyx spinifer pallidus= new subspecies + +Pallid Spiny Softshell + +Plates 39 and 40 + +_Holotype._--TU 484, alcoholic adult male; obtained from Lake Caddo, +Caddo Parish, Louisiana on June 27, 1947, by Fred R. Cagle and party +(Pl. 39, lower, left). + +_Paratypes._--Forty-two specimens: TU 481, 490, 678 (hatchlings), TU +381, 472, 488 (immature males), TU 475, 478, 486, 1232, 1291, 10170 +(adult males), TU 399, 487 (immature females), TU 469 (adult female), +Caddo Lake, Caddo Parish, Louisiana; TU 15818 (immature male), TU +15819 (adult male), Cross Lake, Caddo Parish, Louisiana; TU 1253, +13211 (adult males), TU 13266 (immature female), Sabine River, 8 miles +southwest Merryville, Beauregard Parish, Louisiana; TU 13281-82 (adult +males), TU 13280, 13265 (immature females), TU 13303-04, 13306 (adult +females), Sabine River, 8 miles southwest Negreet, Sabine Parish, +Louisiana; SM 2375 (adult male), Wallace Bayou, De Soto Parish, +Louisiana; TU 1122 (adult male), Lacassine Refuge, Louisiana; UMMZ +92754 (adult male), 5 miles west Iowa, Calcasieu Parish, Louisiana; KU +40174-76, OU 27297 (adult males), OU 27290 (immature female), Lake +Texoma, 2 mi. E Willis, Marshall County, Oklahoma; KU 50832 +(hatchling), mouth of Caney Creek, 4 miles southwest Kingston, +Marshall County, Oklahoma; CNHM 15474 (immature female), Kiowa County, +Oklahoma; KU 2966-67 (immature females), KU 2934, 2947 (adult males), +KU 2973 (adult female) Lewisville, Lafayette County, Arkansas. + +_Description of holotype._--Carapace circular, widest at level of +posterior edge of hyoplastra; margin entire; dorsal surface +"sandpapery" to touch; pale rim separated from ground color of +carapace by well-defined, slightly ragged, blackish line; pale rim +approximately 2.1 times wider posteriorly (4.7 mm.) than it is +laterally (2.2 mm.); pale rim increasingly narrower anteriorly, absent +in nuchal region; tubercles along anterior edge of carapace triangular +with sharp tips becoming flattened and inconspicuous at level of +insertions of arms; ground color of carapace brownish having pattern +of small whitish tubercles; most whitish tubercles inconspicuous, of +pinpoint size, giving surface of carapace "sandpapery" effect; largest +white tubercles posteriorly, approximately 1.2 millimeters in +diameter; whitish tubercles smaller anteriorly, largest approximately +0.6 millimeters in diameter; whitish tubercles tend to form two +parallel lines coincident with longitudinal sutures of neurals +posteriorly in center of carapace; certain features of bony carapace +evident through overlying skin; carapace highest in region of third +and fourth neurals, forming obtuse, gently sloping, vertebral keel; +undersurface of rear margin of carapace whitish having pinkish tinge +and no markings; maximum length, 16.8 centimeters; greatest width, +14.3 centimeters. + +Plastral surface extending slightly farther forward than carapace, +whitish having pinkish tinge and no dark markings; anterior and +posterior lobes rounded, posterior lobe more acutely; certain features +of bony elements of plastron visible through overlying skin; maximum +length, 12.2 centimeters. + +Head extended, terminating in flexible snout; septal ridges projecting +into each rounded nostril; tip of snout darkened; jaws open, each +covered by fleshy lips except anteriorly where horny portions exposed; +dark triangular mark in front of eyes, base line uninterrupted, +slightly curved anteriorly, connecting anterior margins of orbits; +eyelids having blackish dots, especially upper, closing eyes; small +blackish dots on dorsal surface of head; pale postocular stripe +dark-bordered, interrupted; pale portion of stripe traversed by black +line; pale subocular blotch margined by broken blackish border; side +of head having contrasting blackish marks on pale background; +postlabial stripe having lower blackish border on right side of head; +chin with ill-defined marks, not contrasting on grayish background; +well-defined, ragged black line on side of neck separating dorsal +coloration from immaculate ventral coloration; small dark dots on +dorsal surface of neck; dorsal surface of head and neck olive or +brownish, becoming paler laterally and toward insertion of neck; +maximum width of head, 2.1 centimeters. + +Forefeet and hind feet well-webbed each having five digits; each limb +having nails on first three digits; each forelimb with four +antebrachial scales, three of which have free edge; each hind limb +with two horny scales, one smooth on posterodorsal surface and other +with free edge on posteroventral surface; contrasting pattern of +blackish marks, mostly roundish, on pale background of grayish-white. + +Tail terminating in flexible point; penis partly exposed; cloacal +opening extending beyond posterior edge of carapace; tail having +dorsal grayish band flanked by interrupted blackish lines; dark marks +encroaching ventrally at tip of tail. + +Undersurface of soft parts of body whitish, with pinkish tinge; dark +marks lacking on soles, present on webbing and palms; dark marks +arranged in linear fashion coincident with digits. + +_Range._--Southern Oklahoma, eastern Texas, extreme southwestern +Arkansas, and the western half of Louisiana; Red River drainage and +rivers that drain into the Gulf of Mexico east of the Brazos River +drainage in Texas and west of the Atchafalaya River drainage in +Louisiana. The Brazos River drainage is inhabited by a population that +more closely resembles _pallidus_ than _guadalupensis_ (see comments +under subsection entitled "Remarks"; see map, Fig. 19). + +_Diagnosis._--Juvenal pattern of white dots that are usually absent or +inconspicuous, but sometimes distinct and small, on anterior third of +carapace, and not surrounded with dark ocelli; white dots often absent +on posterior half of carapace of hatchlings; white spots, rarely as +large as two millimeters in diameter, not encircled with black ocelli +on adult males; pale rim of carapace less than four times wider +posteriorly than laterally. + +_Description._--Plastral length of smallest hatchling, 3.3 centimeters +(KU 50832); of largest male, 16.0 centimeters (SM 2375); of largest +female, 30.5 centimeters (TU 13213). + +Surface of carapace in hatchlings uniform pale brown or tan; small +white tubercles absent or inconspicuous on anterior half of carapace, +but evident on posterior half of carapace, sometimes well-defined (TU +481), but usually inconspicuous (TU 678, 490); pale rim of carapace +less than four times wider posteriorly than laterally. + +Adult males resembling description of holotype; small whitish +tubercles or dots rarely two millimeters in diameter on posterior half +of carapace, smaller and usually inconspicuous on anterior half of +carapace (TU 13281, 486); well-defined whitish tubercles occasionally +on anterior half of carapace (KU 40174); white tubercles not +surrounded with black ocelli; pattern of white dots seemingly less +contrasting in _pallidus_ than in _guadalupensis_, owing to pale brown +or tan carapace; small tubercles along anterior edge of carapace +equilateral or conical having sharp tips. + +Large females usually having pale brown carapaces with slightly +contrasting, brownish, mottled and blotched, patterns; white +prominences often evident posteriorly and anteriorly in middle of +carapace and in nuchal region; tubercles along anterior edge of +carapace equilateral or conical in shape. + +Pattern on side of head and snout variable and of no diagnostic value; +postocular stripe uninterrupted having dark borders (UMMZ 92754), or +interrupted having pale segment behind eye (TU 13282); other +variations in pattern shown on TU 10170 and 15818; pale stripes on +snout having dark inner borders that join and form acute angle (TU +381), or lacking dark inner borders and having uninterrupted dark line +connecting anterior margins of orbits (TU 13280); other variations in +pattern on snout shown on TU 1232, 1291 and 15819; specimens +representing illustrations of variation in pattern on snout (Fig. 5 d, +e, f) all from same locality, Lewisville, Lafayette County, Arkansas; +contrasting pattern on side of head of dark marks on pale background; +contrasting pattern of dark marks on dorsal surface of limbs; markings +on hind limbs generally larger than those on forelimbs; small or fine +markings of some specimens reducing contrast in pattern (TU 478, 488); +carapace sometimes having few small blackish dots confined to margin +(CNHM 15474, TU 487, 1253, 13266); ventral surface of plastron and +soft parts of body whitish and usually lacking dark markings; small +blackish marks often occurring on flap of carapace, in region of +bridge, or on chin and throat (TU 399, 469, 475, 472, 13281). + +Ontogenetic variation in PL/HW, mean PL/HW of specimens having +plastral lengths 7.0 centimeters or less, 4.15, and exceeding 7.0 +centimeters, 5.32; ontogenetic variation in CL/CW, mean CL/CW of +specimens having plastral lengths 8.5 centimeters or less, 1.10, and +exceeding 8.5 centimeters, 1.14; mean CL/PCW, 2.12; mean HW/SL, 1.38 +(including subspecies _guadalupensis_); mean CL/PL, 1.36. + +_Variation._--In 1953, I casually glanced at a hatchling softshell +from the Calcasieu River drainage in the private collection of Mr. +Wilfred T. Neill; the specimen was considered by Neill (1951:15) as +"... an intergradient one (with the _hartwegi-spinifer_ population in +the lower Mississippi drainage)." The hatchling does deviate from +"typical" _pallidus_ in having darkish flecks posteriorly on the +carapace. + +I have seen only one adult male (USNM 94457) from the Sabine River +drainage (Orange County, Texas) that shows characteristics of +_guadalupensis_ (white dots on carapace encircled with small black +ocelli); another adult male (USNM 94456) from the same locality +resembles _pallidus_. Those two USNM specimens were mentioned by Neill +(1951:13) as indicating intergradation with "... the mixed +_spinifera-hartwegi-asper_ populations of Louisiana." + +Two adult males (SM 2889, Pl. 40, bottom, left, and TCWC 471, Trinity +River drainage) have blackish ocelli surrounding the white dots on the +posterior part of the carapace; two large females (TU 14402, Pl. 40, +bottom, right, plastral length, 17.5 cm., and TU 14417 plastral +length, 21.3 cm., both from the Trinity River) have contrasting +mottled and blotched patterns with white dots visible on the carapace. +These turtles show alliance with _guadalupensis_. + +Some individuals from the Brazos River drainage have features +suggesting those that are characteristic of _guadalupensis_. +Hatchlings may have large white dots on the anterior half of the +carapace (USNM 55601). Adult males may have dusky ocelli surrounding +the white dots on the carapace (TU 14169, 14559.1, 14559.2). The +whitish dots, rarely as large as two millimeters, are never so large +as in _guadalupensis_ (three mm. in diameter), and are usually smaller +anteriorly than posteriorly; TU 14169 has white dots approximately the +same size (1.2 mm.) on the anterior half as on the posterior half of +the carapace. The tubercles on adult males are equilateral or +subconical, usually having sharp tips (TU 14348, 14559.1, 14559.2); +the tubercles on large females are subconical, resembling the end of a +bullet, and, in both sexes the tubercles are less conical than those +on specimens of _pallidus_ from farther east. + +Three specimens from the Brazos River drainage are particularly +impressive in their alliance with _guadalupensis_. SM 2556, an adult +male, has large white dots that are encircled with black ocelli on the +posterior half of the carapace, but lacks white dots on the anterior +half. TNHC 14068, a hatchling, has small black dots interspersed with +the larger white dots posteriorly. CNHM 46289 has large white spots on +the carapace that are surrounded with two to four black dots; +scattered black dots also intermix with white spots on the surface of +the carapace (less extensive anteriorly). + +Color notes taken from a freshly-killed adult male (KU 47121) from the +Brazos River, seven miles below Whitney Dam, Bosque-Hill county line, +Texas, are: Carapace pale brown or tan bordered by black line, having +pale lemon yellow rim; yellowish-cream spots on carapace faintly +surrounded with black stippling; dorsal surface of soft parts of body +olive having black marks and patches of grayish; webbing on limbs +having golden or yellowish hue, brighter distally; interorbital region +brown; black-bordered, postocular stripe orange-cream; snout and side +of head olive having pale areas of orange-cream; iris cream having +black stripe; yellowish at juncture of dark dorsal and pale ventral +coloration with orangish tinge on forelimbs and head; tail pale brown +or tan, flanked by black borders that suffuse laterally into +lemon-yellow; undersurface whitish, pale yellow on neck, bluish-gray +on throat. + +_Comparisons._--_T. s. pallidus_ most closely resembles _T. s. +guadalupensis_, but can be distinguished from that subspecies in +having small white tubercles, rarely two millimeters in diameter, on a +pale background, that are not surrounded by blackish ocelli, and are +usually absent, or not conspicuous on the anterior third of the +carapace in adult males; also there are usually no conspicuous white +tubercles or dots on the anterior third of the carapace in hatchlings. +Many adult males of _pallidus_ from the Brazos and some from the +Trinity River drainages often have dusky or black ocelli surrounding +the white dots posteriorly on the carapace; males from these river +systems may be distinguished from _guadalupensis_ in having most, if +not all, white dots on the anterior half of the carapace smaller than +those posteriorly, and a pale brown carapace (in life, usually darker +in _guadalupensis_). _T. s. pallidus_ (and _guadalupensis_) is +distinguished from _emoryi_ in lacking a widened pale rim posteriorly, +and in having small white spots on the anterior half of the carapace. +_T. s. pallidus_ resembles _guadalupensis_ and _emoryi_ in having +white spots on the carapace in adult males. _T. s. pallidus_ differs +from _spinifer_, _hartwegi_ and _asper_ in lacking blackish dots or +ocelli that occur in the center of the carapace. _T. s. pallidus_ +resembles _emoryi_ but differs from _guadalupensis_ in lacking black +ocelli surrounding the white spots. _T. s. pallidus_ resembles +_spinifer_, _hartwegi_ and _asper_ but differs from _guadalupensis_ +and _emoryi_ in having tubercles along the anterior edge of the +carapace that are conical having sharp tips in males, and conical in +large females. + +_T. s. pallidus_ resembles _spinifer_ and _hartwegi_ but differs from +the other subspecies in having a narrow head. _T. s. pallidus_ differs +from _emoryi_ but resembles the other subspecies in having a wider +carapace. _T. s. pallidus_ resembles _emoryi_ and _guadalupensis_, and +differs from the other subspecies in having the carapace widest +farther posterior than one-half the length of the carapace. The snout +of _pallidus_ and _guadalupensis_ is shorter than in _spinifer_ and +_hartwegi_, but longer than in _emoryi_. _T. s. pallidus_ differs from +_asper_ but resembles the other subspecies in having a relatively long +plastron. + +_Remarks._--Intergradation of the subspecies _pallidus_ and +_guadalupensis_ is of a clinal nature in which populations +successively show a gradual resemblance to _guadalupensis_ from +western Louisiana and eastern Texas westward to central Texas. Because +the sharpest break in this cline of characters occurs between the +Colorado and Brazos River drainages, the turtles living in the Brazos +River drainage and eastward are referred to _pallidus_, whereas those +in the Colorado River drainage and westward are referred to +_guadalupensis_. For further comments on intergradation between these +two subspecies, see the account of _T. s. guadalupensis_. + +Taylor (1935:217-18) reported on some specimens of _Amyda spinifera_ +that were obtained by Mr. R. E. McEntyre in "... the spring and summer +of 1926, chiefly about Lewisville, Lafayette County (Arkansas)." Of +the catalog numbers listed by Taylor from Lewisville, 58 (KU, +alcoholic) represent _pallidus_. Three, having the same locality data, +have features that are characteristic of _hartwegi_. KU 2944 (one of +three specimens having this catalog number) is a female having a pale, +mottled and blotched carapace approximately one foot in length; there +are remnants of two dark ocelli, and many widely-scattered, +well-defined dark spots near the periphery of the carapace. KU 2963 +(one of three specimens having this catalog number) is an adult male +that has solid, blackish dots on the entire surface of the carapace. +KU 2964 (one of two specimens with this catalog number) is an adult +male that has ocelli approximately five millimeters in diameter on the +carapace (indistinct in center of carapace). + +Lewisville is situated in the drainage basin of the Red River and is +approximately eight miles east of the Red River and 30 miles west of +the westernmost tributary of the Ouachita River drainage. _T. s. +pallidus_ occurs in the Red River drainage; _hartwegi_ occurs in the +Ouachita River drainage. Perhaps there is intergradation between +_pallidus_ and _hartwegi_ in the intervening streams. There is no data +to indicate from which river or stream each specimen obtained by +McEntyre came; one would presume that all specimens came from the Red +River drainage. But this is not certain. Certainly the 47 specimens +designated herein as _pallidus_ came from the Red River drainage. I +suspect that KU 2944, 2963 and 2964 were obtained from tributaries of +the Ouachita River drainage. + +_T. s. pallidus_ intergrades with the _spinifer-hartwegi_ population +where the Red River joins the Mississippi River in the lower +Mississippi Valley in Louisiana. The majority of 13 juvenal specimens +from the Red River near Shaw, Concordia Parish, Louisiana (USNM +99862-69, 99871-75), resemble _pallidus_ in having inconspicuous white +tubercles on a pale brown carapace. The white tubercles are +conspicuous in USNM 99871. Some specimens have a few small dark dots +confined to the margin of the carapace, as do some "variant" +individuals from well within the geographic range of _pallidus_. USNM +99865 is referred to _hartwegi_ because the carapace is covered with +dark ocelli approximately one millimeter in diameter. Some specimens +from farther west in the Red River drainage are referred to +_hartwegi_. One (USNM 100420) of three from Natchitoches Parish, +Louisiana (TU 5763, USNM 100420-21), having blackish dots on the +carapace, is applicable to _hartwegi_. Of two turtles from Grant +Parish, Louisiana (TU 5647, 12735), only 12735 has dark dots and +ocelli (_hartwegi_). One specimen from Rapides Parish, Louisiana (TU +14040), having dark dots on the entire surface of the carapace, is +referred to _hartwegi_. + +Most specimens from the lower Atchafalaya River drainage are referable +to _pallidus_. Eastward, intergradation occurs with the +_spinifer-hartwegi_ population; USNM 100089-90 from Assumption Parish, +near Napoleonville, Louisiana, are referred to _pallidus_. TU 11983, +from Bayou Lafourche, Raceland, La Fourche Parish, and TU 13698.11, +from Bayou Gauche in St. Charles Parish, Louisiana, are juvenal males +that combine the characteristics of _pallidus_ and _hartwegi_; the +carapaces are covered with blackish spots and posteriorly have +distinct whitish dots. The population in the Atchafalaya River more +closely resembles _pallidus_ than it does _hartwegi_ or _spinifer_. In +former times the Atchafalaya River was presumably continuous solely +with the Red River (inhabited by _pallidus_). Now, these two rivers +and the Mississippi River are interconnected in east-central +Louisiana. A large volume of water of the Mississippi drainage is +conveyed to the Gulf of Mexico by the Atchafalaya, and someone has +said that by approximately 1975, unless man interferes, two-thirds to +three-fourths of the total volume of water of the Mississippi River +will be drained by the Atchafalaya. One can expect, therefore, an +increase in the influence of the _hartwegi-spinifer_ population in the +Atchafalaya River drainage. + +_Specimens examined._--Total 270, as follows: ARKANSAS: _Lafayette_: +KU 2930-37, 2939-40, 2942, 2944 (two of three specimens bear this +catalog number), 2945-57, 2958 (2), 2959-61, 2963 (two of three +specimens bear this catalog number), 2964 (one of two specimens bears +this catalog number), 2965-73, 2987-89, 3056, Lewisville. + +LOUISIANA: _Acadia_: USNM 100151-59, Mermentau River. _Assumption_: +USNM 100089-90, Bayou Lafourche, "near" Napoleonville. _Beauregard_: +TU 1231-32, 1253-55, 1291, 13211, 13266, Sabine River, 8 mi. SW +Merryville. _Bienville_: TU 5649-50, Lake Bistineau. _Caddo_: TU 381, +397-99, 469-72, 474-90, 678, 10170, Caddo Lake: TU 15818-19, Cross +Lake. _Calcasieu_: UMMZ 92754, 5 mi. W Iowa. _Cameron_: TU 1122, +Lacassine Wildlife Refuge. _Concordia_: USNM 99862-64, 99866-69, +99871-75, Red River, "near" Shaw. _De Soto_: SM 2374-75, Wallace +Bayou. _Grant_: TU 5647, Lake Iatt. _Iberville_: USNM 83985, 2 mi. E +Mounds; USNM 100239-41, Grand Lake west of White Castle; USNM 100380, +Plaquemine; USNM 100412, 100414-15, 100419, Spanish Lake, "near" St. +Gabriel. _Jefferson Davis_: Calcasieu River drainage, WTN (no number, +see page 524). _Natchitoches_: TU 5763, Bermuda; USNM 100421, "near" +Natchitoches. _Sabine_: TU 13210, 13212-13, 13265, 13280-82, 13303-06, +Sabine River, 8 mi. SW Negreet. _St. Martin_: USNM 100160, Bayou +Chene; USNM 100650, Atchafalaya. _St. Mary_: USNM 100395-97, 100404, +100409-10, Berwick Bay near Morgan City. + +OKLAHOMA: _Atoka_: OU 8966, Rock Creek, 10 mi. E Atoka; OU 8978, McGee +Creek, 7 mi. SW Daisy. _Caddo_: ANSP 100, Washita River, Fort Cobb. +_Choctaw_: OU 27126, Mayhew Creek, 2 mi. NW Boswell. _Comanche_: OU +4130, 4266, 5390, 8333, 12953, 19986, Wichita Mountains Wildlife +Refuge. _Jackson_: OU 13012, 6 mi. E El Dorado. _Kiowa_: CNHM 15474. +_Le Flore_: OU 6791, Kiamichi River, 8 mi. W Arkansas State Line. +_McCurtain_: OU 2149-50, 2152, 2155, 17126-28, 17185, 2 mi. SW +Smithville; USNM 70397, Red River. _Marshall_: KU 40175-76, 50830-31, +50847, OU 27290, 27297, 27562-63, TU 16076 (5), 16175 (6), 16662 (5), +Lake Texoma, 2 mi. E Willis; KU 50832, mouth of Caney Creek, 4 mi. SW +Kingston. _Pushmataha_: OU 2151, 2157; OU 11365, Buffalo Creek, 5 mi. +NW Tuskahoma. + +TEXAS: _Archer_: TU 16174, 16668-69, Lake Diversion. _Bell_: SM +5667-69, Nolan Creek. _Bosque_: KU 47121, 7 mi. below Whitney Dam, +Brazos River. _Brazos_: BCB 4436, 10 mi. E College Station; BCB 4437, +17 mi. S College Station; BCB 4438, 4 mi. N Bryan; KU 50833, 4 mi. W +College Station; SM 2556, TCWC 472, Wickson Lake; TCWC 539, Little +Brazos River; TCWC 4692, 8 mi. NE Bryan; TCWC 5121, 2 mi. S College +Station; TCWC no number. _Clay_: TCWC 7258, 8 mi. NW Ringgold, +Montague County; TU 16667.1, 3 mi. W Byers. _Dallas_: MCZ 3987, "near" +Dallas; ANSP 13243, Dallas. _Donley_: ANSP 13440, S of Clarendon. +_Eastland_: KU 3132, Cisco. _Galveston_: TCWC 7251, Alta Loma. +_Harris_: UMMZ 92753, Little Cypress Creek, 1 mi. N Westfield; USNM +94335-36, "near" Houston. _Harrison_: USNM 95386, 16.5 mi. SE Caddo +Lake. _Hill_: TU 14169, Richland Creek, 0.7 mi. W Mertens. _Leon_: +CNHM 46290, 5 mi. W Marquez; TCWC 8994, 8996, 6 mi. NW Normangee. +_Liberty_: TU 14402, 14417, Trinity River, "near" jct. with Big Creek. +_McLennan_: BCB 4665-66, 6 mi. NNE McGregor; SM no number, 2037, 2452, +2552, 2558, 2560, 2640, 5263, 6533, Lake Waco; SM 0185, Middle Bosque +River; SM 2104, 6732, Upper Bosque River; SM 5072, Bull Hide Creek; UI +2399, 1.5 mi. W China Springs; UMMZ 64063, Waco; USNM 55601. +_Madison_: TCWC 471, 517, Twin Lakes. _Montgomery_: TCWC 540, 3 mi. S +Conroe. _Nacogdoches_: TNHC 14112, Legg Creek, 5 mi. S Douglass. +_Orange_: UMMZ 117060, 3 mi. S Orange; USNM 94456-57, Orange. +_Randall_: TTC 576, Palo Duro Canyon, 15 mi. SE Canyon. _Shackelford_: +TU 14547, Clear Fork Brazos River, Fort Griffin State Park. +_Somervell_: TCWC 8995, TU 14559 (4), Brazos River, 5-6 mi. E Glen +Rose. _Trinity_: SM 2889, Groveton. _Walker_: TNHC 20829, 5 mi. E New +Waverly. _Waller_: TNHC 14068, 2.7 mi. E Brazos River on US 90. +_Williamson_: MCZ 1627 (2); TU 14348, San Gabriel River, 6.5 mi. E +Georgetown. _County unknown_: ANSP 13448, Wichita River; USNM 7640, +Brazos River. + +_Records in the literature._--LOUISIANA: _Cameron_: Sabine Refuge +(Cagle and Chaney, 1950:386). + +OKLAHOMA: _Le Flore_: 6 mi. W Page. _McCurtain_: 14 mi. SE Broken Bow +(Trowbridge, 1937:301). + +TEXAS: _Bosque_: Bosque River, "near" Valley Mills (Strecker, 1928:6). +_Harris_: Addicks (Brown, 1950:250). _Henderson_: Cedar Creek +(Strecker, 1926a:7). _Jefferson_: 12 mi. SW Port Arthur (Guidry, +1953:56). _Liberty_: Daisetta (Brown, _loc. cit._); San Jacinto River +(Strecker, 1915:15). _McLennan_: "near" Crawford (Brown, _loc. cit._). +_Orange_: 1 mi. N Bridge City (Guidry, _loc. cit._). _Tarrant_: +Trinity River, Fort Worth (Stejneger, 1944:66). _Taylor_: Abilene +(KKA). _Tyler_: Colmisneil (Siebenrock, 1909:603). _Walker_: 6 mi. E +Huntsville (TCWC 329, listed in card file). _Wheeler_: 5 mi. N Wheeler +(Brown, _loc cit._). + + +=Trionyx ater= Webb and Legler + +Black Softshell + + _Trionyx ater_ Webb and Legler, Univ. Kansas Sci. Bull., 40:21, + pls. 1 and 2, 1960, April 20. + +_Type._--Holotype, KU 46903, alcoholic female; obtained 16 km. S +Cuatro Ciénegas, Coahuila, México, by John M. Legler (and party), +September 6, 1958. + +_Range._--Basin of Cuatro Ciénegas, central Coahuila, Mexico (see map, +Fig. 22). + +_Diagnosis._--Posterior margin of carapace of some females having fine +corrugations, edge often ragged, and no pale outer margin; septal +ridges reduced in adult males; over-all dorsal coloration (in +preservative) dark, lacking contrasting patterns. + +_Description._--Plastral length of adult male, 9.6 centimeters (KU +46911); of largest female, 18.4 centimeters (KU 46903). + +Adult male: anterior edge of carapace smooth; septal ridges reduced; +pale outer rim, and small, whitish, dots posteriorly on carapace; +surface of carapace slightly gritty or sandpapery posteriorly; snout +broadened; over-all dorsal coloration dark gray or slate; contrasting +pattern on soft parts of body lacking; ventral surface whitish having +few blackish marks posteriorly on undersurface of carapace. + +Females: posterior margin of carapace usually having fine +corrugations; edge of carapace posteriorly often ragged; pale rim of +carapace absent; mottled and blotched pattern not contrasting on +blackish carapace; dorsal surface of soft parts of body dark gray or +slate, lacking contrasting pattern; ventral surface of carapace and +posterior part of plastron usually having many blackish flecks and +markings; tubercles lacking on anterior edge and in center of carapace +posteriorly; septal ridges well developed. + +Medial angle of epiplastron (as observed through overlying skin) bent +at angle of approximately 90 degrees. Other osteological characters +presumably as in _spinifer_. + +Range in length of plastron (cm.) of 11 females (mean follows +extremes); 10.8-18.4, 15.0; proportional measurements of 12 specimens +(including adult male, mean follows extremes): PL/HW, 4.70-5.43, 4.93; +CL/CW, 1.28-1.43, 1.32; CL/PCW, 1.98-2.42, 2.15; HW/SL, 1.22-1.58, +1.37; CL/PL, 1.29-1.44, 1.36; some females (especially KU 46908) have +noticeably elongate carapaces. + +_Variation._--Corrugations best developed on two largest females (KU +46903, 46906), even present on ventral surface of carapace posteriorly +and on dorsal surface of tail; development of corrugations not +ontogenetic phenomenon as posterior margin relatively smooth on KU +46908 (plastral length, 16.0 cm.) but relatively rugose on KU 46909, +which is smaller (plastral length, 13.9 cm.); smallest female (KU +46904) and adult male having posterior margin smooth; smallest female +having indication of pale outer rim and small whitish dots posteriorly +on carapace, and dark, obtusely-angular line, connecting anterior +margins of orbits; blackish marks on ventral surface reduced on KU +46904, 46910, 46912, and UI 43510; UI 43510 (plastral length, 16.3 +cm.) resembles _T. s. emoryi_ in having more contrasting mottled +pattern on carapace and limbs, indication of pale outer rim on +carapace, and dark line connecting anterior margins of orbits; ventral +surface of tail and hind limbs often tinged with red. + +Color notes from life of young female, topotype (KU 53755) are: +mottled carapace dark brown, pale areas buff; dorsal surface of head +mottled, olive-brown, pale areas buff; iris orange-buff; upper and +lower lips yellow-orange; dorsal surface of limbs olive-brown having +yellow to buff suffusion and small blackish marks; pale areas on +webbing yellow; ventral surface whitish having yellow at margin of +carapace, on neck and limbs. + +_Comparisons._--_T. ater_ most closely resembles _T. spinifer_ +(especially the subspecies _emoryi_) in having a gritty or +"sandpapery" carapace (reduced, tubercles more scattered), whitish +dots on posterior third of carapace (small females and adult male) and +a dark line connecting anterior margins of orbits (smallest female). +Prior to acquiring the characteristic darkened, dorsal ground color, +the pattern on the head and limbs seems to be that of _T. s. emoryi_. + +_T. ater_ resembles _T. muticus_ in having reduced septal ridges in +males, a smooth anterior edge of carapace (especially males), and no +enlarged prominences on the anterior edge of the carapace or +posteriorly in the center of the carapace on large females. _T. ater_ +resembles _T. ferox_ in having an over-all dark coloration dorsally +with no contrasting patterns on adults. + +_T. ater_ probably is a small species resembling _T. muticus_ and _T. +spinifer emoryi_. The head is wide in _T. ater_, resembling that of +_T. ferox_, and closely approaching that of _T. spinifer emoryi_ and +_T. s. guadalupensis_. _T. ater_ resembles _T. ferox_ and _T. s. +emoryi_ in having a narrow carapace. _T. ater_ resembles _T. s. +emoryi_, _T. s. guadalupensis_ and _T. s. pallidus_, but differs from +_T. muticus_, _T. ferox_ and the other subspecies of _T. spinifer_ in +having the carapace widest farther posterior than one-half the length +of the carapace. _T. ater_ resembles _T. ferox_ and _T. s. emoryi_ in +shortness of snout. The plastron is short in _T. ater_ and most +closely resembles that of _T. s. pallidus_, _T. s. guadalupensis_, and +_T. s. emoryi_. + +_Remarks._--_T. ater_ is confined to permanent, clear-water ponds in +the basin of Cuatro Ciénegas. The male and 11 females (KU) were taken +at the type locality (a pond known locally as Tío Candido); the other +female (UI 43510) was taken from a pond approximately seven miles +northward (known locally as Anteojo). _T. spinifer emoryi_ also occurs +in the basin of Cuatro Ciénegas. Males and females of _emoryi_ were +collected in the Río Mesquites (Río Salado drainage) that drains the +basin; two adult males of _emoryi_ were taken from the clear-water +ponds--one from the type locality of _ater_ (KU 46907), and the other +(KU 53757) from a pond (known locally as El Mojarral) from which no +_ater_ were obtained. This demonstrated sympatry indicates that the +two kinds are not conspecific. + +However, the nature and frequency of occurrence of characters of _T. +ater_, suggest that it is subspecifically related to _T. spinifer_--in +effect, a darkened race of _T. s. emoryi_. The diagnostic characters +of fine corrugations on the posterior margin of the carapace and +blackish marks on the ventral surface do not occur on every female of +_ater_. Too, the dorsal coloration of living females (dark brown-buff) +is paler than that of preserved specimens (dark gray-slate). +Furthermore, a hatchling (CNHM 47367) recorded from Cuatro Ciénegas, +Anteojo, is not distinguishable from _emoryi_. + +The mention of absence of septal ridges in males of _T. ater_ in the +original description (Webb and Legler, 1960:22) should be amended. The +septal ridges in the only known adult male are reduced; a small, +whitish ridge is present on the medial surface of each nostril, but is +not conspicuous in anterior view. The one adult male of _ater_ is +distinguished from _T. s. emoryi_ principally on the over-all dark, +dorsal coloration with concomitant loss of pattern, the noticeably +broadened snout, and the reduced septal ridges. The last character +mentioned possibly is variable in _ater_ (and in _emoryi_ in this +region) in view of the variation in development of the ridge on four +male _emoryi_ from the basin: well-developed on KU 53757 (Mojarral) +and KU 46907 (Tío Candido); reduced on KU 53752 (Río Mesquites), +resembling development in _ater_; and, reduced on right side only on +KU 53753 (Río Mesquites). + +Presumably, the continued erosive action at the headwaters of the Río +Salado has permitted the invasion of this drainage into the formerly +isolated basin of Cuatro Ciénegas. In the basin, however, I know of no +evidence of a direct aquatic contact between the headwater streams and +the isolated, clear-water, ponds. How _emoryi_ entered the ponds is +unknown. Some of the ponds are tapped by small, man-made, irrigation +canals, but, so far as I know, these are not connected to the river. +The ponds have permanent water and are often separated by several +miles of arid environment. Overland dispersal between waterways is +possible in time of flooding. Local residents tell of the infrequent +sale of softshells in Cuatro Ciénegas, which hints at their dispersal +via the agency of man. The underlying gypsum substrate of the valley +has been subjected to considerable erosion; the ponds observed have +deep holes, and small caverns and grottos. There are conflicting +reports concerning subterranean connections between ponds. Possibly +there are underwater connections between some ponds and the headwater +streams of the Río Mesquites. Whatever the dispersal route for +_emoryi_ into the ponds has been, it is strange that the same route +has not been traversed by _ater_, permitting its occurrence in the Río +Mesquites. + +On the basis of morphological criteria, I suspect that _ater_ and +_emoryi_ are genetically compatible. Possibly there is only sporadic +entrance of _emoryi_ into the ponds inhabited by _ater_, or the +accessible dispersal routes for _emoryi_ have been relatively recent +and there has been insufficient time for genetic adaptation. _T. ater_ +is maintained as a full species because of the occurrence of two +distinct males (KU 46907, _emoryi_, and KU 46911, _ater_) in the same +pond (Tío Candido, the type locality). These two specimens are +contrasted in a photograph accompanying the type description (Webb and +Legler, 1960: Pl. II). The restricted distribution of _ater_, and its +characteristics suggest a relict population derived from a +_ferox_-like ancestor that may be in the process of becoming extinct. + +There are two specimens in the CNHM recorded from Cuatro Ciénegas. One +is a female (CNHM 55661) having a plastral length of 19.0 centimeters, +and no specific locality other than Cuatro Ciénegas. I examined this +specimen before I knew of the existence of _ater_, and noted no +unusual features; I have not re-examined the specimen. It is +considered representative of _emoryi_. The second is a hatchling (CNHM +47367) having a plastral length of 3.2 centimeters, recorded from +Cuatro Ciénegas, Anteojo. The carapace is dark tan having small +whitish dots intermixed with a few indistinct, small, blackish specks +posteriorly. The specimen is indistinguishable from _emoryi_. + +_Specimens examined._--Total 12, as follows: COAHUILA: KU 46903-06, +46908-12, 53755-56, 16 km. S Cuatro Ciénegas; UI 73510, 5.7 mi. W +Cuatro Ciénegas. + +_Records in the literature._--Schmidt and Owens (1944:103) record +_emoryi_ from Cuatro Ciénegas (no museum numbers listed); presumably +their reference is to CNHM 55661. + + +=Trionyx muticus= Lesueur + +Smooth Softshell + +_Range._--United States from extreme western Pennsylvania, southern +Minnesota and South Dakota south to the Gulf of Mexico in Alabama, the +western end of the panhandle of Florida, and the eastern half of Texas +(see map, Fig. 22.) + + [Illustration: FIG. 22. Geographic distribution of _Trionyx ater_ + and _Trionyx muticus_. 1. _T. muticus muticus_. 2. _T. muticus + calvatus_. 3. _T. ater_.] + +_Diagnosis._--Septal ridges absent; anterior edge of carapace smooth, +lacking prominences; juvenal pattern of large dusky spots (sometimes +ocellate), or small dusky (not black), dots and short lines; side of +head usually devoid of markings except for pale, usually +uninterrupted, postocular stripe. + +Size small; head narrow; snout long; ventral surface of supraoccipital +spine broad proximally, lacking median ridge; foramen magnum evenly +rounded, ovoid; opisthotic-exoccipital spur absent; distal part of +opisthotic wing truncate; lateral condyle of articular surface of +quadrate tapered posteriorly, smaller than medial articular surface; +angle of epiplastron obtuse, approximately 100 degrees; callosity on +epiplastron sometimes covering entire surface; bony bridge wide in +relation to length. + +_Description._--Septal ridges absent; external characteristics +variable (see accounts of subspecies); range in length, in +centimeters, of plastron of ten largest specimens of each sex, (mean +follows extremes), males, 11.8-14.0, 12.3; females, 17.7-21.5, 18.9; +ontogenetic variation in PL/HW, mean PL/HW of specimens having +plastral lengths 7.0 centimeters or less, 4.16, ranging from 7.1 to +13.0 centimeters, 5.82, and, exceeding 13.0 centimeters, 7.04; little +ontogenetic variation in CL/CW, mean CL/CW of specimens having +plastral lengths 8.0 centimeters or less, 1.15, and exceeding 8.0 +centimeters, 1.16; mean CL/PCW, 1.97; mean HW/SL, 1.22; mean CL/PL, +1.39. + +Greatest width of skull usually at level of squamosal (79%); foramen +magnum ovoid; opisthotic-exoccipital spur usually absent (97%); distal +part of opisthotic wing truncate, sometimes visible in dorsal view; +lateral condyle of articular surface of quadrate tapered posteriorly, +smaller than medial articular surface; maxillaries not in contact +above premaxillaries; combination of seven neurals, seven pairs of +pleurals, and contact of seventh pair of pleurals (38%), or eight +neurals, seven pairs of pleurals, and separation of seventh pair of +pleurals (41%); angle of epiplastron obtuse, greater than 90 degrees; +callosities well-developed, frequently on preplastra and epiplastron +of adults. + +_Comparisons._--The absence of septal ridges distinguishes _muticus_ +from _ferox_, all subspecies of _spinifer_, and _ater_ (ridges are +reduced in males of _ater_). The smooth anterior edge of the carapace +distinguishes _muticus_ from all other American kinds except _ater_ +and some individuals of _T. s. emoryi_. _T. muticus_ resembles only +_ater_ and _ferox_ in usually lacking a well-defined, contrasting +pattern of blackish marks on the dorsal surface of the limbs. _T. +muticus_ resembles _ferox_ and differs from _spinifer_ and _ater_ in +lacking a gritty or "sandpapery" carapace on adult males. Adult males +of _T. muticus calvatus_ and some individuals of _T. m. muticus_ from +the Colorado River in Texas further resemble _ferox_ in having +postocular stripes with thick black borders. + +_T. muticus_ is the smallest species in North America; the maximum +size of the plastron in adult males is approximately 14.0 centimeters +(16.0 cm. in _spinifer_) and of adult females 21.5 centimeters (31.0 +cm. in _spinifer_). Males and females of _muticus_ are sexually mature +at approximately the same size as some _T. s. emoryi_; also, the great +development of the plastral callosities in _muticus_ corresponds to +that in some _emoryi_. The head is narrower in _muticus_ than in +_ferox_ or _spinifer_. The carapaces of specimens of _muticus_ +exceeding plastral lengths of 8.0 centimeters are wider than those of +_ferox_, _ater_, _T. s. emoryi_ and _T. s. guadalupensis_ of +corresponding size. _T. muticus_ differs from _ater_ and three +subspecies of _spinifer_ (_pallidus_, _guadalupensis_, _emoryi_) in +having the carapace widest at a plane approximately one-half the +length of the carapace. The snout is longer in _muticus_ than in +_ferox_ and _spinifer_. _T. muticus_ differs from _ferox_ but +resembles _spinifer_ in having a relatively short plastron. + +The skulls of _muticus_ differ from those of _ferox_ but resemble +those of _spinifer_ in usually having the skull widest at the level of +the squamosals. Skulls of _muticus_ resemble those of _ferox_ but +differ from those of _spinifer_ in usually lacking a well-developed +opisthotic-exoccipital spur. Skulls of _muticus_ are different from +those of _ferox_ and _spinifer_ in having the 1) ventral surface of +the supraoccipital spine widest proximally, lacking a medial ridge, 2) +foramen magnum ovoid, 3) distal part of opisthotic wing truncate, 4) +lateral condyle of articular surface of quadrate tapered posteriorly, +smaller than medial articular surface, and 5) maxillaries not in +contact above premaxillaries. + +Plastrons of _muticus_ differ from those of _spinifer_ and _ferox_ in +having an obtusely-angled epiplastron, relatively large callosities +in adults, and a wide hyo-hypoplastral bridge (in relation to length). + +_Remarks._--Agassiz (1857:399) regarded Lesueur's _Trionyx muticus_ as +the type species of the genus _Amyda_ and the only species known to +belong to the genus _Amyda_. Stejneger (1944:7, 9, 12) proposed the +generic name _Euamyda_ as a new name for the North American _Amyda +mutica_ as understood by Agassiz. _Euamyda_ was proposed for use only +if Agassiz's understanding was found to be correct. Actually, +Stejneger thought that the Old World and New World kinds concerned +were congeneric, and that the type species of the genus _Amyda_ was +the Old World species _Amyda javanica_ Schweigger (= _Testudo +cartilaginea_ Boddaert). + +If _Trionyx muticus_ Lesueur is considered to be generically distinct +from other soft-shelled turtles, _Euamyda_ Stejneger, 1944, is +available as a generic name with _Trionyx muticus_ Lesueur, 1827, as +the type species (by monotypy). + +_Geographical variation._--_Trionyx muticus_ shows no obvious +character gradients; the variation is mostly discontinuous and unlike +that in _T. spinifer_. On the basis of differences in the juvenal +pattern and pattern on head, _T. muticus_ can be divided into two +subspecies. + + +=Trionyx muticus muticus= Lesueur + +Midland Smooth Softshell + +Plates 45, 46, and 53 + + _Trionyx muticus_ Lesueur, Mém. Mus. Hist. Nat. Paris, 15:263, + pl.7, December, 1827. + + _Trionyx muticus muticus_ Webb, Publ. Mus. Nat. Hist. Univ. Kansas, + 11:520, August 14, 1959. + + _Potamochelys? microcephala_ Gray, Proc. Zool. Soc. London, p. 87, + 1864. + +_Type._--Lectotype, Museum d'Histoire Naturelle, Paris, No. 8813; +dried carapace and plastron; obtained from the Wabash River, New +Harmony, Posey County, Indiana, by C. A. Lesueur in August, 1827 (Pl. +53). + +_Range._--Central United States; in the Mississippi River drainage +from extreme western Pennsylvania, southern Minnesota and South Dakota +south to Tennessee, Louisiana and Oklahoma; streams of the Gulf Coast +drainage from the Mississippi River in Louisiana westward into Texas +including the Colorado River drainage (see map, Fig. 22). + +_Diagnosis._--Juvenal pattern of dusky dots and usually short lines or +bacilliform marks; ill-defined pale stripes on snout usually evident +just in front of eyes; pale postocular stripe lacking thick, black +borders that are approximately one-half width of pale stripe (except +some in the Colorado River drainage of Texas). + +_Description._--Plastral length of smallest hatchling, 2.1 centimeters +(INHS 3458); of largest male, 14.0 centimeters (CNHM 92003); of +largest female, 21.5 centimeters (KU 2308). + +Juvenal pattern of dusky, grayish marks lacking sharp margins, and +usually consisting of both small spots and short streaks or dashes, +the former predominating; short streaks or dashes occasionally lacking +(TU 14375, Pl. 45, bottom, left; UMMZ 92751); markings variable in +number, few and widely spaced, or several and closely approximated +(Pl. 45, top, topotypes); pale rim separated from ground color by +ill-defined, dusky margin; pattern on adult males well-defined +resembling that of hatchlings (TU 16172.1, 16173), scarcely +discernable (TU 13294), or absent (TU 1242); mottled and blotched +pattern on carapace usually contrasting in large females. + +Pale stripes extending forward from eyes usually not more than half +distance to tip of snout; inner borders of pale stripes on snout +usually absent or dusky and indistinct, occasionally blackish (TU +14606); outer borders of pale stripes darker than inner borders, +usually blackish; pale stripes on snout occasionally absent (CNHM +7845, UMMZ 92665, TU 5989, none of these specimens being large +females); pale postocular stripe having narrow, dusky or blackish +borders (especially UMMZ 92751, TU 14436); pale postocular stripe +usually complete, occasionally interrupted having prominent +dark-bordered anterior segment just behind eye (TU 14416); lower +border of postocular stripe usually in contact with dusky postlabial +line; no other markings on side of head; pattern on dorsal surface of +soft parts of body not contrasting, composed of closely approximated +fine markings that are little darker than background, over-all +coloration pale grayish; occasionally, few larger and more contrasting +markings on hind limbs (UMMZ 92751, TU 14436). + +Underparts white, usually lacking markings; occasional dusky markings +on plastral area (UMMZ 110502), dark spots or flecks on undersurface +of carapace (BCB 6043, UMMZ 92666), or markings on throat (UMMZ +95032). + +Surface of carapace smooth in adult males; large females lacking +prominences posteriorly in center of carapace or in nuchal region; +anterior edge of carapace smooth in both sexes, but occasionally +having regularly spaced furrows or wrinkles (Fig. 8g). + +_Variation._--Short dusky lines and streaks seem to be lacking from +the juvenal pattern on the carapace more often in southern populations +(Gulf Coast drainage of Texas) than in northern populations +(Mississippi River drainage). I have seen one female, KU 48229 (Pl. +46, bottom, left), plastral length 14.5 centimeters that retained a +well-defined juvenal pattern, and lacked a mottled and blotched +pattern. + +Color notes from life of 11 turtles, KU 55296-306, (eight adult males, +three immature females) from the Kansas River at Lawrence, Douglas +County, Kansas, are: Buff-yellow rim of carapace, sometimes having +pale orange tinge; dusky, dark brown markings on pale brown or tannish +carapace of males; dark and pale brown mottled and blotched pattern on +carapace of females (smallest specimens having plastral length, 11.0 +cm.), many having orangish or buffy hue; soft parts of body brownish +to olive-green dorsally, many having small, blackish marks on hind +limbs; webbing of limbs yellowish; pale orange, some yellow, laterally +at juncture of dark dorsum and pale ventrum (to a lesser extent on +hind limbs); pale orange in some suffusing onto dorsal surface of soft +parts of body; black-bordered postocular stripes in males having +orangish tinge (pattern somewhat obscured in females); whitish ventral +surface in some having pale orangish tinge here and there; many having +dusky, grayish flecking on plastral area and anterior ventral surface +(most intense on 55306 giving appearance of grayish suffusion). + +I have seen only three specimens from the Colorado River drainage in +Texas. Two of these (UMMZ 92751, TU 14436) are characterized by much +black pigmentation. A contrasting pattern of relatively large black +marks occurs on the dorsal surface of the soft parts of the body, +especially on the hind limbs, and the pale postocular stripes have +thick black borders. UMMZ 92751, having a plastral length of 5.5 +centimeters, has a juvenal pattern of widely-spaced dark dots that +lacks short lines. The other _muticus_ from the Colorado River (CM +3055), a large female 19.0 centimeters in plastral length, has +ill-defined postocular stripes lacking dark borders, although a small +dusky blotch occurs on the right side of the head. + +_Comparisons._--_T. m. muticus_ differs from _T. m. calvatus_ in +having pale stripes on the snout, a juvenal pattern of small dusky +spots (usually lacking ocellate spots) and short lines, and a pale +postocular stripe lacking thick, blackish borders (except in some +turtles from the Colorado River system of Texas). One unique +characteristic of _muticus_ is the short, dusky lines in the juvenal +pattern; these marks, however, are occasionally absent. + +_Remarks._--_Trionyx muticus_ generally has been considered a distinct +species since its description by Lesueur (1827:263-66, Pl. 7); +Wied-Neuwied (1865:53), at least, questioned the identity of +_muticus_, believing it to be based on a secondary sexual difference +of _T. spiniferus_. Lesueur did not designate a type in the +description, and mentioned that he had seen only three specimens (_op. +cit._:264). Stejneger (1944:17-18) discussed two mounted specimens +(Nos. 787 and 788) in the Natural History Museum at Paris, and +mentioned that No. 787 was designated "... as the type on the printed +label (although presumably not done by Lesueur)." Dr. Jean Guibé (_in +litt._ September 24, 1959) informed me that Nos. 787 and 788 are +numbers without value and correspond, respectively, to catalog numbers +8813 and 8814. In addition, the Museum possesses an alcoholic +specimen, No. 564, obtained by Lesueur from the Wabash River, that +seems to have been acquired by the museum after the publication of the +original description. No. 8813 is regarded as a lectotype. + +Gray (1864:87) described the species _microcephalus_ and questionably +included it in the genus _Potamochelys_ Fitzinger, 1843; the locality +was stated as "Sarawak (Wallace)." Gray especially noted the small +elongate head and believed that the acquisition of adult specimens +would prove that it belonged to a new genus. Later, Gray (1869:221) +proposed the generic name _Callinia_ as a new name for _Aspidonectes_ +as understood by Agassiz (1857:403). Gray referred _microcephala_ to +_Callinia_ (_op. cit._:214, 222) and recognized also _Amyda mutica_ +(_op. cit._:212). Baur (1888:1121) remarked that "_Callinia +microcephala_ Gray, of the British Museum, with the locality Sarawak, +is _Amyda mutica_ Les." The species _microcephalus_ has since been +considered a synonym of _Trionyx muticus_. Schmidt (1953:110) +designated the type locality as New Harmony, Indiana. + +Müller (1878:641) listed the species _Trionyx muticus_ from México as +follows: "*b. in Alcohol. Mexico. 1872. [2]." Smith and Taylor +(1950:18, footnote) wrote that the record required confirmation. Webb +and Legler (1960:24) questionably referred this record to the synonomy +of _T. ater_, which resembles _muticus_. _T. muticus_ is not known to +occur in México. According to Dr. Lothar Forcart (_in litt._) of the +Naturhistorische Museum in Basel, Switzerland, only one specimen on +which Müller based his record is extant. My examination of this +specimen reveals that it is a hatchling _T. s. emoryi_, plastral +length 3.5 centimeters, bearing catalog number 1032; there are no +additional data of collection. + +Strecker and Williams (1927:16) mentioned one specimen of _muticus_ +that was obtained at Christoval, Tom Green County, Texas, and I +presume this is the basis for Pope's mention of this species from Tom +Green County, Texas (1949:319). Although I do not doubt that _T. +muticus_ occurs in Tom Green County, this record possibly is based on +_T. spinifer_ because, 1) there are no specimens of _muticus_ in the +Strecker Museum from Tom Green County, but there is one specimen of +_spinifer_ (SM 3282), and in none of Strecker's publications is there +any mention of _spinifer_ from Tom Green County, and 2) Strecker had, +at least once, misidentified the two species; his record of _muticus_ +from Wallace Bayou, Louisiana (Strecker and Frierson, 1926:last page, +no numbers), represents _T. spinifer pallidus_ (SM 2374-75). + +_Specimens examined._--Total 261, as follows: ALABAMA: _County +unknown_: USNM 118167, Wheeler Reservoir, Tennessee River. + +ARKANSAS: _Franklin_: KU 19459-60, Ozark. _Lafayette_: KU 2938, 3057, +Lewisville. _Lawrence_: CNHM 92003, Imboden; CNHM 92005, Powhatan; +USNM 59214, Black River, Black Rock. _Marion_: TU 14606 (2), White +River at Cotter. _Prairie_: KU 1831, 1868, 1870, 1874-76, 1930-31, +1957-63, 2294-302, 2305-06, 2308-09, 2838-41, 3002, White River, +DeVall's Bluff. + +KANSAS: _Barber_: USNM 95185-86, 1 mi. S Lake City. _Doniphan_: KU +1872, 1878, 1964, Doniphan Lake. _Douglas_: KU 2220, 16148, 23230, +40179, 50825-26, 55296-306, Kansas River, Lawrence; KU 45065-66, 1 mi. +N, 1.5 mi. W Lakeview. _Ford_: KU 51516, Ford. _Kearny_: KU 48216, 4 +mi. S, 1.5 mi. W Deerfield. _Marshall_: KU 48228, Blue Rapids. +_Pottawatomie_: KU 48229-33, 48238, 2 mi. E Manhattan, Riley County. +_Reno_: USNM 95260, 6 mi. E Turon. _Riley_: KU 46861, 48234-35, 4 mi. +N Manhattan; KU 48236, 2 mi. NE Randolph. _Sedgwick_: UMMZ 95362, +Wichita. _Shawnee_: UMMZ 95366-67, Topeka. _Sumner_: USNM 95415, 3 mi. +SE Oxford. _Washington_: KU 48237, 8 mi. S Hanover. _Woodson_: KU +45064, 1 mi. E, 2 mi. S Neosho Falls. _County unknown_: USNM 51528. + +ILLINOIS: _Cass_: INHS 2146, Beardstown. _Coles_: INHS 1965-67, 3 mi. +S Charleston. _Jackson_: INHS 5894, 6.5 mi. N Aldridge, Union County; +UMMZ 81570, Mississippi River. _Jasper_: INHS 2412, Rose Hill. +_Jersey_: INHS 2156-58, Grafton. _Mason_: INHS 2147, Cedar Creek. +_Mercer_: INHS 3458, Keithsburg. _Monroe_: INHS 4088, 3 mi. NE +Columbia. _Morgan_: CNHM 6028, INHS 2148, Meredosia. _Pope_: CNHM 2463 +(30), Golconda. _Schuyler_: UI 40-41, Crooked Creek. _Shelby_: INHS +2283, Holliday. _Wabash_: INHS 5228, Mt. Carmel. + +INDIANA: _Daviess_: UMMZ 110234, White River, 1.5 mi. W Elnora. +_Jefferson_: USNM 8337, Madison. _Knox_: UMMZ 111880-81, "near" Decker +Chapel. _Posey_: INHS 7278-80, 7447, TTC 798, Wabash River, 2-2.5 mi. +S New Harmony; UMMZ 110598, 8 mi. NW Mt. Vernon. + +IOWA: _Allamakee_: UMMZ 92657, 1/4 mi. W Victory, Vernon County, +Wisconsin; UMMZ 92658-64, Mississippi River, "near" Lansing. _Boon_: +UMMZ 92665, Des Moines River at Ledge State Park. _Greene_: UMMZ +92666, 3.5 mi. N Scranton. _Muscatine_: USNM 53521, 54733-34, 54742, +60054-56, Fairport. + +LOUISIANA: _Beauregard_: TU 1242, Sabine River, Merryville. _Caddo_: +CNHM 7845, Gayles. _Catahoula_: USNM 113228, Jonesville. _Concordia_: +USNM 99870, Red River, "near" Shaw. _Ouachita_: TU 5989, Monroe. +_Richland_: USNM 100422, Rayville. _Sabine_: TU 13163, 13294, Sabine +River, 8 miles SW Negreet. _St. James_: TU 7543, Vacherie. _St. Mar_: +USNM 100406, Berwick Bay, "near" Morgan City. _Vernon_: KU 41380, +46777, Sabine River NW Burr Ferry. + +MINNESOTA: _Hennepin_: AMNH 4761-62, Fort Snelling. + +MISSISSIPPI: _Washington:_ USNM 92605, Greenville. _County unknown_: +USNM 115939. + +MISSOURI: _Clark_: USNM 59267, 59278, Alexandria. _Daviess_: UMMZ +95505, Grand River, 1 mi. S Jameson. _St. Louis_: SM 2052, St. Louis. +_Wayne_: UMMZ 82823, St. Francis River. + +NEBRASKA: _Webster_: UMMZ 89526, Republican River, 2 mi. E Inavale. + +OKLAHOMA: _Cleveland_: OU 5480-81, 6473, South Canadian River, 4 mi. +SE Norman. _Hughes_: KU 50845, 4 mi. N Atwood. _Kay_: OU 9741, 8 mi. E +Ponca City. _Le Flore_: OU 2148; OU 27390, Poteau River below Wister +Dam. _Love_: OU 27472, Hickory Creek, 9 mi. E Marietta. _Major_: OU +8597, 7 mi. E Orienta. _Marshall_: KU 50827-29, 50848, 50853, OU +27593-94, TU 16077 (4), Lake Texoma, 2 mi. E Willis. _McIntosh_: OU +8993, 4 mi. W Onapa. _Oklahoma_: OU 10137, Lake Oberholser. _Payne_: +UMMZ 89629, Cimarron River, 3 mi. E Ripley; UMMZ 90002, 19 mi. SE +Stillwater. _Pottawatomie_: OU 25176-83, South Canadian River, 5 mi. +SW Shawnee. _Roger Mills_: OU 12472. _Sequoyah_: OU 9006, Illinois +River, 2 mi. NE Gore. _Tulsa_: UMMZ 95032 (4), Arkansas River at +Tulsa. _Woodward_: CNHM 15472-73; OU 8599-600, 5 mi. E, 1 mi. N +Woodward. + +SOUTH DAKOTA: _Yankton_: UMMZ 110499-500, Missouri River at Fort +Randall; UMMZ 110501-02, Missouri River at Yankton. + +TENNESSEE: _Benton_: UMMZ 53198, Trotter's Landing. _Lake_: USNM +102677, Reelfoot Lake. _Obion_: USNM 102910, Reelfoot Lake. + +TEXAS: _Archer_: TU 16173, Lake Diversion. _Baylor_: TU 16172 (2), +Lake Kemp. _Brazos_: TCWC 7250, Bryan. _Clay_: TCWC 7248-49, 7259-61, +8 mi. NW Ringgold, Montague County; TU 16667, 3 mi. W Byers. +_Grayson_: UI 2419, Lake Texoma. _Gregg_: SM 6685, near Gladewater; +USNM 22629, Sabine River, 5 mi. S Longview. _Liberty_: TU 14416, +14375, Trinity River, "near" jct. with Big Creek. _McLennan_: BCB +6030, 6043, SM 2557, 2561, Lake Waco. _Matagorda_: CM 3055, Colorado +River, Bay City. _San Saba_: TU 14436, San Saba River, 11 mi. NNW San +Saba. _Tarrant_: UMMZ 92750, Worth Lake, Fort Worth. _Wharton_: UMMZ +92751, Colorado River, Wharton. + +NO DATA: MCZ 1594 (erroneously recorded from Mobile, Alabama); USNM +029261, 59982. + +_Records in the literature._--ARKANSAS: _Garland_: Hot Springs (Combs +and Hurter _in_ Strecker, 1924:47). _Jefferson_: Pine Bluff. +_Pulaski_: Little Rock. _Sebastian_: Fort Smith (Hurter and Strecker, +1909:21). + +ILLINOIS: _Adams_: Quincy (Garman _in_ Cahn, 1937:179). _Alexander_: +Horseshoe Lake (Cahn, _loc. cit._); Cairo (Garman _in_ Cahn, _loc. +cit._). _Carroll_: 5 mi. S Savanna (Stejneger, 1944:24). _Clay_: +Louisville. _Clinton_: Carlyle. _Crawford_: Robinson (Cahn, _loc. +cit._). _Cumberland_: Embarrass River (Peters, 1942:183). _Fayette_: +Vandalia. _Gallatin_: Shawneetown (Cahn, _loc. cit._). _Hancock_: +between Warsaw and Hamilton (Stejneger, _op. cit._:23). _Jackson_: +Murphysboro. _Jasper_: Newton. _Marion_: Centralia. _Mason_: Havana. +_Massac_: symbol on map. _Menard_: Petersburg. _Peoria_: Peoria. +_Randolph_: Chester (Cahn, _loc. cit._). _Richland_: Olney (Stejneger, +_loc. cit._). _Rock Island_: Rock Island. _St. Clair_: East St. Louis +(Cahn, _loc. cit._). _Union_: (Cagle, 1942a:199). _White_: Carmi. +_Whiteside_: Sterling (Cahn, _loc. cit._). _Woodford_: Mackinaw Creek +(Garman _in_ Cahn, _loc. cit._). + +INDIANA: _Carroll_: "near" Delphi (Agassiz, 1857:400). _Vigo_: Terre +Haute (Blatchley, 1891:22). + +IOWA: _Des Moines_: "near" Burlington (Agassiz, 1857:400). _Dubuque_: +Mississippi River, 8 mi. S Dubuque (Goldsmith, 1945:447). _Lee_: +Keokuk (Stejneger, 1944:23). + +KANSAS: _Barber_: 5 mi. SE Lake City; Salt River, S of Aetna (Burt, +1935:321). _Cowley_: symbols on map (Smith, 1956:157). _Gray_: +Arkansas River, 1 mi. W Cimarron (Clarke, 1956:215). _Leavenworth_: +Missouri River, Fort Leavenworth (Brumwell, 1951:207-08). _McPherson_: +Lindsborg (Breukelman and Smith, 1946:112). _Pratt_: State Fish +Hatchery, "near" Pratt (Taylor, 1933:269). _Trego_: Wakeeney +(Stejneger, 1944:24). + +KENTUCKY: _Fleming_: Fox. _Rowan_: Triplett (Welter and Carr, +1939:130). _County unknown_: Ohio River (Funkhouser, 1925:71). + +LOUISIANA: _De Soto_: Bayou Pierre (Strecker and Frierson, 1926:last +page, no numbers). + +MINNESOTA: _Houston_: Brownsville (Breckenridge, 1944:183). _Winona_: +Homer (Stejneger, 1944:23). + +MISSISSIPPI: _Warren_: Vicksburg (Cook, 1946:185). + +MISSOURI: _Jackson_: Fry's Lake (Anderson, 1942:219). _Jefferson_: +Meramec River (Boyer and Heinze, 1934:199). _County unknown_: Osage +River (Agassiz, 1857:400). + +NEBRASKA: _Franklin_: 1/2 mi. S Franklin; 1 mi. SE Naponee. _Furnas_: +4 mi. E Cambridge. _Lancaster_: Lincoln. _Nemaha_: Peru. _Thayer_: +(Hudson, 1942:102). _Thomas_: (Smith, 1958:36). + +NEW MEXICO: _San Miguel_: Conchos River above Conchos Dam (Shields and +Lindeborg, 1956:120). + +OHIO: _Brown_: mouth White Oak Creek, Higginsport. _Muskingum_: "near" +Gaysport. _Pike_: Scioto River in Camp Creek, Newton and Scioto Twps.; +Pike Lake. _Scioto_: Scioto River in Clay and Rush Twps.; Scioto +River, Portsmouth; Scioto River, 3 mi. N Rushtown. _Tuscarawas_: +Tuscarawas River, 2 mi. below Gnadenhutten; "near" Winfield. +_Washington_: Dam No. 2, Muskingum River, northern edge of Marietta; +Ohio River, 4 mi. SE Marietta (Conant, 1951:156, 264). + +OKLAHOMA: _Alfalfa_: 6.5 mi. NE Ingersoll. _Comanche_: Camp Boulder, +Wichita National Forest (Ortenburger and Freeman, 1930:188). +_McCurtain_: _Pushmataha_: (Ortenburger, 1927:100). + +PENNSYLVANIA: _Allegheny_: Neville Island, Ohio River below Pittsburgh +(Atkinson, 1901:154). _Clarion_: Allegheny River at Foxburg (Netting, +1944:85). + +?SOUTH DAKOTA: _County unknown_: Fort Mackenzie, Missouri River, 6-8 +mi. below Cedar Island (Stejneger, 1944:15). + +TENNESSEE: _Lake_: Mississippi River (Parker, 1948:29). _Pickett_: +Obey River at Eagle Creek Ford (Shoup, Peyton and Gentry, 1941:75). + +WISCONSIN: _Crawford_: _Pepin_: Mississippi River (Breckenridge, +1944:183; Pope and Dickinson, 1928:82). + + +=Trionyx muticus calvatus= Webb + +Gulf Coast Smooth Softshell + +Plate 47 + + _Trionyx muticus calvatus_ Webb, Univ. Kansas Publ. Mus. Nat. + Hist., 11:519, 1 fig., 2 pls., August 14, 1959. + +_Type._--Holotype, UI 31071, hatchling, sex undetermined, alcoholic; +obtained from Pearl River, Roses Bluff, 14 miles northeast Jackson, +Rankin County, Mississippi, by William F. Childers on August 25, 1952. + +_Range._--Southeastern United States from the Florida Parishes of +Louisiana eastward to the western end of the panhandle of Florida; +rivers of the Gulf Coast drainage from the Escambia River drainage, +Florida, westward to Louisiana and Mississippi including the Pearl +River drainage. The eastern extent of geographic range is not known +(see map, Fig. 22). + +_Diagnosis._--Juvenal pattern of large circular spots, often ocellate; +no stripes on dorsal surface of snout; pattern on dorsal surface of +limbs of fine markings, not in contrast with ground color; pale +postocular stripes having thick black borders approximately one half +width of pale stripe on adult males. + +_Description._--Plastral length of smallest hatchling, 3.0 centimeters +(TU 17301); of largest male, 11.8 centimeters (KU 47118); of largest +female, 18.0 centimeters (TU 13473). + +Juvenal pattern of dusky, circular spots, some ocellate, lacking short +lines and streaks; number of spots variable; some spots on carapace of +hatchlings may have maximum diameter of three millimeters (TU 17301); +pale rim of carapace having dusky, ragged, inner border; juvenal +pattern on adult males absent or usually evident, at least posteriorly +(TU 17306.1). + +Dorsal surface of snout lacking pale stripes just in front of eyes; +pale postocular stripe having thick, black borders on adult males, but +narrower, dusky or blackish borders on juveniles and large females; +lower border of postocular stripe usually in contact with dusky +postlabial line; no other markings on side of head; pattern on dorsal +surface of soft parts of body of closely approximated, fine markings +that are not in contrast with ground color, over-all coloration +grayish; occasionally few larger and more contrasting markings, +especially on hind limbs and anteriolateral surface of forelimbs. + +Underparts whitish, lacking markings, occasional black flecks or dusky +marks posteriorly along ventral edge of carapace (TU 17306.3). + +Surface of carapace smooth in adult males; large females lacking +prominences posteriorly in center of carapace or in nuchal region; +anterior edge of carapace smooth in both sexes, but occasionally +having regularly spaced furrows or wrinkles on hatchlings. + +_Comparisons._--_T. m. calvatus_ can be distinguished from _T. m. +muticus_ by the absence of pale stripes on the snout just in front of +the eyes, in having pale postocular stripes that have thick, black +borders on adult males, and in having a juvenal pattern of large, +circular spots that are often ocellate and three millimeters in +diameter (no short lines). + +_Remarks._--I have not seen specimens of _calvatus_ from the +Tombigbee-Alabama river drainage; presumably Cook's record (1946:185) +from Lowndes County, Mississippi, represents this subspecies. + +It is still not certain that _calvatus_ occurs in streams that drain +into Lake Pontchartrain, Louisiana; TU 17236 from the Amite River that +lacks a diagnostic character is questionably referred to _calvatus_ +(Webb, 1959:524). As mentioned previously _T. s. asper_ shows little +evidence of intergradation with _T. spinifer_ in the Mississippi River +drainage; _asper_ is present in streams of the Lake Pontchartrain +drainage. _T. m. calvatus_ presumably shows a corresponding +relationship with _T. m. muticus_ in the Mississippi River drainage. +There are no specimens that indicate intergradation between _calvatus_ +and _muticus_; _calvatus_ is expected in streams that drain into Lake +Pontchartrain, Louisiana. Probably _calvatus_ occurs eastward in the +Apalachicola drainage system. + +_Specimens examined._--Total, 38 as follows: FLORIDA: _Escambia_: KU +47116, 50852, 50854-55, 50835-36, TU 13473, 16682, 17301, 17302 (2), +Escambia River, 2 mi. E, 1 mi. N Century. + +LOUISIANA: _East Baton Rouge_: TU 17236, Amite River, "near" Baton +Rouge. _Washington_: TU 13795, Bogue Chitto River, Enon; TU 17303 (5), +TU 17304 (4), Pearl River, "near" Varnado. _No data_: TU 17305. + +MISSISSIPPI: _Lawrence_: KU 47117-19, TU 16956, USNM 7655, Pearl River +within 4 mi. of Monticello; TU 17306 (4), Pearl River, 9 mi. S +Monticello. _Marion_: USNM 95133-34, Pearl River, Columbia. _Perry_: +MSC uncatalogued (3), 3 mi. SE New Augusta. _Rankin_: UI 31071, Pearl +River, Roses Bluff, 14 mi. NE Jackson. + +_Records in the literature._--MISSISSIPPI: _Forrest_: no data. +_Jones_: Crawford Bridge. _Lowndes_: Columbus, Lake Park (Cook, +1946:185). + + + + +NATURAL HISTORY + + +Habitat + +Most writers who describe the general habitat of soft-shelled turtles +mention large rivers and streams having some current, and large +permanent, quiet bodies of water having soft mud or sand bottoms, but +note the general avoidance of temporary water. The impermanence of water +in the ponds and "charcos" of headwaters of streams may preclude the +presence of softshells from these otherwise suitable habitats. +Seemingly, soft-shelled turtles are not restricted to particular local +situations or microhabitats in a continuous aquatic environment as are +some kinds of fish, which seem to be more or less confined to riffle +areas or deep holes. Certain activities of softshells such as burying +themselves in soft sand in shallow water or seeking crawfish and other +food over a gravel-rock substrate or one that is débris-laden, are best +carried on in different habitats. Repeated observations of turtles that +are probably engaged in a specific activity in a restricted area may +lead to erroneous general conclusions regarding the over-all preference +for a specific habitat. Perhaps this accounts for Conant's statement +(1951:156) that "In the lower portion of the Scioto River [Ohio] it +appears that the present species [_muticus_] is abundant while +_spinifer_ is almost entirely absent." + +Cagle (1954:181) wrote that softshells "inhabit the extreme headwaters +and smaller tributaries." Other statements in the literature indicate +the variety in kinds of habitat. In Louisiana, Beyer (1900:44) +mentioned _spinifer_ as abundant "in all inland waters, preferring, +however, such bayous which have sloping and sandy banks upon which +they are fond of sunning themselves." Viosca (1923:41) reported +soft-shelled turtles as characteristic "of the large silt-bearing +rivers ... such as the Pearl, Amite, Mississippi and Atchafalaya." +Cagle and Chaney (1950:386) wrote that _spinifer_ in Louisiana was +found in greatest abundance in streams having some current, but that +individuals were also common in quiet areas; the habitats recorded +were: False River--a lake of clear water supporting an abundance of +submerged vegetation, the shallow ends having mats of water hyacinth; +Lakes Iatt and Bistineau--cypress swamps having clear or muddy water; +Caddo Lake--a large lake having a light oil film on the surface of the +water, and vegetation toward the shore consisting of cattails, water +lilies and water hyacinths, and along the bank of cypress and willow +trees; Caddo Lake Spillway--muddy with swift current; Sabine +River--swift current, traps set in quieter backwater areas or near +cypress logs in river; Lacassine Refuge--traps set in inlets and coves +of ship channel having vegetation of water hyacinth, alligator grass, +and along bank, saw grass, cypress knees and snags. Stejneger +(1944:59) reported _spinifer_ taken in barrow pits in Mississippi. + +In Southern Illinois, Cagle (1942:160) recorded _spinifer_ in drainage +ditches (normally having several feet of water and a lush growth of +aquatic vegetation) that connect inland swamps to the Mississippi +flood-plain but dry up periodically, and in Elkville Lake, an +artificial lake having much aquatic vegetation in shallow areas (_op. +cit._:157). Myers (1927:339) recorded a _spinifer_ from Indiana from a +"tiny brook." In east-central Illinois P. W. Smith (1947:39) recorded +_spinifer_ in mud-bottomed dredge ditches, lakes, ponds, small streams +and rivers, whereas _muticus_ was found to prefer rivers having clean, +sandy bottoms and was not taken from lakes or small streams. This +restriction in habitat preference of _muticus_ is again emphasized by +Smith and Minton (1957:346) who wrote that in Illinois and Indiana, +_muticus_ "generally avoids lakes and minor streams." Weed (1923:48), +however, recorded _muticus_ (and _spinifer_) from Meredosia Bay, +Illinois, presumably a broad, shallow, muddy ox-bow lake of the +Illinois River. + +In Minnesota, _spinifer_ has been taken from the Mississippi River, +which is described as fairly swift having a fluctuating water level, +sandy islands, mud banks, a bed of pebbles and large boulders, and +abundant crawfish (Breckenridge, 1955:5). In Michigan, Edgren +(1942:180) recorded _spinifer_ from a "very small muck-bottomed lake." +Evans and Roecker (1951:69) recorded _spinifer_ from Long Point, Lake +Ontario, which is a "broad sand spit, straight on the lakeward side +but irregular with wet flats and lagoons on the bayside." + +In Kansas, Brumwell (1951:207-08) found "mostly young [_muticus_] ... +in the old ponds left during flood stages of the Missouri River" ... +and _spinifer_ occasionally ... "in the backwaters where stagnant +ponds had been formed." In southcentral Kansas, Burt (1935:321) +reported _muticus_ from "a sandbar at junction of a small creek and +Medicine River" ... and ... a "shallow sand-bottomed, algae-filled +pasture streamlet." The same author reported _spinifer_ from a +"sand-bottomed prairie streamlet" ... and ... "an alga-filled pool +near a stream." Burt (_loc. cit._) remarked that "No ecological +differences in general habitat and field behavior of _mutica_ and +_spinifer_ are evident in Kansas." Clarke (1958:21) observed +_spinifer_ in Long Creek (Osage County, Kansas), which is a winding +stream, characterized by numerous deep holes alternating with rocky +riffles, and having high and wooded banks, and mostly mud bottom but +occasional rock bottom. + +Marr (1944:490) mentioned a _spinifer_ that was obtained on the bank +of a small, mud-bottomed stream in the Texas panhandle, and Linsdale +and Gressitt (1937:222) recorded _spinifer_ from irrigation canals in +Baja California. + +In southern Florida, _ferox_ occurs in all fresh-water habitats +(Duellman and Schwartz, 1958:272). Carr (1940:107) reported _ferox_ as +widely distributed in streams, lakes, big springs and canals. Judging +from the numbers of turtles, "the larger canals in the Everglades must +represent something like an optimum habitat" (Carr, 1952:417). Wright +and Funkhouser (1915:119) wrote that in the Okefinokee Swamp, _ferox_ +was especially abundant where the water is deep and the bottom soft, +and the species was found wherever there were alligators. Deckert +(1918:31) wrote that young _ferox_ were taken in springs and brooks +near Jacksonville, Florida. Marchand (_in_ Carr, 1952:417-19) observed +_ferox_ while water-goggling in Florida and noted that individuals +buried themselves in deep water in white sand, mud or bubbling +mud-sand springs, sometimes where there was vegetation overhead. +Neill (1951:16) collected _ferox_ in marshes, "prairies," flood-plain +lakes, lagoons, ox-bow lakes, mangrove swamps, rivers, creeks, +calcareous spring runs, man-made lakes and lime sinks. The same author +(_loc. cit._) reported taking _agassizi_ (= _asper_) in large muddy +rivers, clear "blackwater" streams, calcareous spring runs, creeks, +marshes, lagoons, ox-bow lakes, flood-plain lakes, lime sinks, +man-made lakes, and smaller ponds. Crenshaw and Hopkins (1955:16), +however, stated that in the area where _T. ferox_ and _T. spinifer +asper_ overlap, "_asper_ is nearly always an inhabitant of fluviatile +situations whereas _ferox_ is equally closely confined to +non-fluviatile lakes and ponds"; in the region of sympatry, Schwartz +(1956:8) reported _ferox_ from "a moderately fast, blackwater stream +[Combahee River, South Carolina]." + +Carr (1952:417) wrote that _ferox_ is not uncommon near the mouths of +streams in brackish waters, where the tide must occasionally take it +to sea, and cited Conant, who told of an individual found at sea in +Bahaman waters; Carr (1940:25) listed _ferox_ as occasional in the +marine-littoral, mangrove swamps, as did Neill (1951:16). Neill +(1958:26-27) mentioned his observance of _ferox_ at the mouth of the +Pithlachascotee River, Pasco County, Florida, where the water is +sufficiently saline to favor the growth of oysters, and added that +commercial fishermen had told him that these turtles are sometimes +netted with loggerhead sea turtles (_Caretta_) in the Indian River. +Neill (_op. cit._:5-6) also noted the presence of _ferox_ on Meritt +Island, which supports an extensive saltwater herpetofauna, off the +coast of Brevard County, Florida. Löding (1922:47) recorded _spinifer_ +from Fig Island, Mobile County, Alabama, which is probably a marine or +brackish water habitat. Cagle and Chaney (1950:386) obtained one +_spinifer_ in a brackish marsh of the Sabine Wildlife Refuge, +Louisiana; the poor trapping returns here (one _Trionyx_ and one +_Pseudemys_ in 408 trap-hours) suggest that fresh-water species are +not abundant in brackish habitats. Neill (1958:26-27) has summarized +the occurrence of soft-shelled turtles in marine and brackish +habitats. + +My own observations indicate a variety of habitat preferences; the +term "relatively clear" refers to waters in which visibility extends +four to six inches below the surface at night using a head-light. + +Individuals of _spinifer_ have been taken in large, deep rivers having +a moderate to swift current, relatively clear water, mostly sand and +clay bottoms, and emergent débris intermittent along the shoreline; +the banks may be steep and of mud having a sparse growth of herbs +(Black Warrior River, south of Tuscaloosa, Alabama), or of low +extensive, sandy bars and beaches (Escambia River, near Century, +Florida, Pl. 50, Fig. 1). A juvenile _spinifer_ was taken by hand +among rocks in quiet water behind a rocky shoal in the large, +deep-channeled Ocmulgee River (near Hawkinsville, Georgia). Several +individuals of _spinifer_ were seen in the Flint River (near +Bainbridge, Georgia), which had a swift current in a wide, deep +channel, sandy or sand-silt banks, few brush piles along shore and +many oölitic, submergent snags on an otherwise sandy bottom; the water +was exceedingly clear and permitted water-goggling (this habitat has +been obliterated by a dam on the Apalachicola River). A large female +_spinifer_ was taken on a set line from the bottom of one of several +deep holes (approximately seven feet) that were connected by shallow +areas or riffles (near headwaters of Escambia River--Escambia Creek, +Escambia County, Alabama). Two large females of _spinifer_ (one +escaped) were taken on a trotline set in a large, deep, isolated +barrow pit near the Escambia River (near Century, Florida); there was +no aquatic vegetation, the water was slightly turbid, and the +substrate was of a sand-silt or mud. + +In Arkansas, _spinifer_ has been taken in large deep rivers having +relatively clear water, a moderate current, steep banks four to 15 +feet high, and a substrate of mud with few rocks (one taken on +trotline, escaped; Black River, near Black Rock, Lawrence County). Two +_spinifer_ were taken (trotline and hoop-net) from a smaller +(approximately 50 feet wide) turbid river having a swift current, +débris along the shoreline, and mud-gravel banks (Petit Jean Creek, +Yell County). Several _spinifer_ and _muticus_ were taken from the +White River (Marion County) having a sand-gravel or bed rock bottom +and clear water; individuals were collected by hand in shallow water +(approximately 3-1/2 feet deep) as they lay on the bottom in the main +channel where the current was moderate to swift or in a quiet-water +side channel having submergent vegetation. + +Lake Texoma, an impoundment on the Red River, having a fluctuating +water level with no permanent stand of aquatic vegetation, a mud-rock +or sand-silt bottom, and turbid water (Pl. 49, Fig. 1) is a suitable +habitat for _spinifer_ and _muticus_. _T. spinifer_ is found in large +rivers having relatively clear water, moderate currents, emergent logs +and débris, and mud or sand banks (Little River, McCurtain County, +Oklahoma, Pl. 48, Fig. 1), or small, shallow, turbid creeks having +sand-gravel channels of pools connected by riffle areas (Mayhew Creek, +Choctaw County, Oklahoma). + +Three _spinifer_ were taken from the Llano River (near Llano, Texas) +in a period of low water level in hoop-nets set in a large quiet-water +pond about four feet deep and having patches of rushes encroaching +into the water from the shore. The river bed of sand, gravel and large +boulders consisted of narrower, swift-water channels, small pools and +riffles, and large ponds. + +Individuals of _T. s. emoryi_ have been taken in large ponds having +little or no current, turbid, deep water, and clay or sand-gravel +banks (Río Purificación, Padilla, Tamaulipas). Two _emoryi_ were +collected from a large pond (Río Sabinas, near Sabinas, Coahuila), +which was connected to an adjoining one by riffle areas and had little +or no current, relatively clear, greenish water, clay or mud banks, a +sand-gravel bottom, and was flanked by brush and large cypress trees. +A few _emoryi_ were trapped in hoop-nets that were set in the Río +Mesquites, a stream in central Coahuila approximately 20 feet wide and +six feet deep, flanked by dense stands of _Phragmites_, and having a +moderate current, relatively clear, pea-green water and a mud-sand +substrate with some gravel; the stream enlarged in some places to form +quiet-water coves (Pl. 48, Fig. 2). One adult male _emoryi_ was taken +from a crystal-clear, dendritic, pond (El Mojarral, near Cuatro +Ciénegas, Coahuila), having shallow areas averaging about two feet but +several deep holes--in one of these at the west end of the pond the +water was being emitted under pressure from an underwater cavern and +"bubbling" at the surface; the vegetation consisted of scattered +patches of water-lilies and stonewort; the bottom was a soft mud-marl, +and in some places was carpeted with shells of small gastropods. This +habitat corresponds to that of the type locality of _T. ater_ (Pl. 49, +Fig. 2); see description in Webb and Legler (1960:26). The water of +the ponds is warm; at 8 p. m. on July 31, 1959, the temperature of the +water at the type locality of _ater_ was 29° C., and the air was 27° +C. + +An immature female _spinifer_ was taken on a trotline in a swift, +clear, cold-water habitat having mud banks and an abundance of brush +piles (Little Tennessee River, Monroe County, Tennessee). _T. +spinifer_ occurs also in large ox-bow lakes having relatively clear +water, extensive mats of submerged vegetation, a soft mud bottom, and +several emergent stumps and fallen logs (Lake Concordia, Concordia +Parish, Louisiana); alligator grass and cypress trees encroached to +the shoreline. + +Locality data of some individuals of _spinifer_, _hartwegi_, _asper_, +_pallidus_ and _emoryi_ that were examined indicated that turtles were +captured in ponds, bayous, sloughs, lakes, impoundments, rivers and +creeks, indicating habitation of essentially all permanent waters. + +A juvenile of _hartwegi_ was seen by Mr. Wendell L. Minckley on a +gravel bar jutting into a small, shallow creek having a mud-gravel +bottom (Carnahan Creek, Pottawatomie County, Kansas); the impounding +of the Big Blue River by the Turtle Creek Dam will obliterate this +habitat. Mr. J. Knox Jones, Jr. reported seeing a large softshell in a +narrow, shallow, clear sandy creek in Holt County, Nebraska. + +_T. s. emoryi_ occurs in large rivers having generally turbid waters, +a moderate to swift current and mud or sand bottoms such as the Río +Grande; this habitat corresponds to that of large rivers in the +western parts of the range of _T. s. pallidus_ (Red and Washita) and +_T. s. hartwegi_ (Canadian and Cimarron). These last-named rivers, in +periods of low water level, often have shallow, clear, flowing water +in parts of the river bed. _T. s. emoryi_ has also been taken from +small creeks having bottoms of rocks and large boulders (Black River +Village, Eddy County, New Mexico; field notes of Sydney Anderson and +Kenneth Shain, June 12-14, 1958). + +I received a hatchling _T. s. guadalupensis_ that was obtained in a +clear, shallow-water stream (Hondo Creek, Bandera County, Texas, on +April 12, 1958). The larger streams and rivers known to be inhabited +by _guadalupensis_ are generally clear having greenish-tinted waters. +The geographic distribution of _guadalupensis_ indicates that that +subspecies occurs principally in those waters that drain the +limestone-mantled, Edward's Plateau off the Balcones Escarpment; the +headwaters are characterized by clear, calcareous streams having +occasional travertine deposits. It is probably this type of habitat to +which Agassiz's statement (1857:408) of "clear, bold and rocky +streams" refers. + +There are a few specimens whose locality data indicate a tolerance of +brackish-water habitats. An adult male _spinifer_ was obtained at +Delacroix Island, St. Bernard Parish, Louisiana, a locality said to +have exceedingly brackish waters (Dr. George H. Bick, St. Mary's +College, Notre Dame, Indiana); this adult male (TU 16170) is unique in +having a mottled and blotched pattern. Another adult male (_spinifer_, +TU 16071) was obtained in shallow water in Lake Pontchartrain at the +mouth of Tchefuncta Creek; the salinity at the time of capture was +recorded as 1.7 (datum from Dr. Royal D. Suttkus, Tulane University), +indicating only slightly brackish water. Two _spinifer_ (USNM +100409-10) and one _muticus_ (USNM 100406) were taken at Berwick Bay, +near Morgan City, St. Mary's Parish, Louisiana; the waters at this +locality are probably brackish. The tolerance of brackish waters +doubtless facilitates the dispersal of these turtles along coastal +marshes and swamps, and into adjacent drainage systems. The greater +number of records in the literature pertaining to _ferox_ suggest that +this species may be more tolerant of brackish and marine waters than +are _spinifer_ or _muticus_. + +In summary, _T. ferox_ occurs in all fresh-water habitats, but chiefly +in lentic habitats in the northern part of its range where it and _T. s. +asper_ are sympatric. _T. ferox_ possibly is more tolerant of brackish +and marine waters than are the subspecies of _spinifer_ and _muticus_. + +The subspecies of _T. spinifer_ occur in all fresh-water habitats. In +the southern part of the geographic range, which overlaps that of _T. +ferox_, _T. s. asper_ occurs principally in running-water habitats. _T. +s. pallidus_ and _T. s. asper_ are tolerant of brackish-water habitats. +_T. s. guadalupensis_, known at present only from rivers and streams, +occurs principally in river systems that drain the Edward's Plateau of +southcentral Texas. _T. ater_ is confined to crystal-clear ponds in +central Coahuila. + +The subspecies _muticus_ occurs in large rivers and streams throughout +its geographic range, but is known from lakes and impoundments +principally in the southern part of its range (the northernmost record +is from Reelfoot Lake, Obion County, Tennessee); there is only one +record of _muticus_ from a small, shallow, headwater creek (Reno County, +Kansas), and only one from a lentic habitat (Meredosia Bay, Illinois) in +the northern part of its range. _T. muticus calvatus_ is known at +present only from rivers and streams. + +The seemingly greater restriction of _muticus_ to running-water habitats +suggests less vagility than in _spinifer_ (Netting, 1944:86). + +Size and coloration are adaptations to habitat. Soft-shelled turtles of +large size are best adapted to mesic, essentially continuous swampy or +marshy habitats, whereas small size is an adaptation to less continuous, +semi-isolated habitats. A turtle of the maximum size attained by _ferox_ +in the habitat of _emoryi_ would, in a general way, probably be more +conspicuous and exposed to its enemies, both in the aquatic environment +and during overland excursions; perhaps the kind and amount of food +would be insufficient. In any event, small size is correlated with the +more arid habitats of the southwest, and large size with mesic ones in +the southeast. _T. ferox_, the largest species, and the smallest +population of _T. spinifer_ (resembling _muticus_) both occur in the +southernmost part of the range of the genus. This situation does not +support the corollary of Bergmann's Rule, that pertains to some groups +of terrestrial reptiles, in which those subspecies occurring farther +north, or in cooler climates during their season of activity, tend to be +smaller. + +Within the species _spinifer_, the _emoryi_ group of subspecies are +pallid having whitish dots on the carapace and lack extensive black +pigmentation; these features seem to confer protective coloration on the +inhabitants of arid, essentially sandy or muddy habitats having +sluggish, turbid waters, whereas the more contrasting patterns of the +_spinifer_ group of subspecies eastward seem more suited to existence in +clearer, swifter waters. + +The occurrence of the two clines, _spinifer-hartwegi_ and +_pallidus-guadalupensis_, in the species _spinifer_ are notable in that +the former occurs mostly in one large continuous drainage system, that +of the Mississippi, and shows no sharp break in the one character +distinguishing the two subspecies whereas populations composing the +_pallidus-guadalupensis_ cline are separated into several river +drainages, and show a relatively sharp break in several characters at +the Brazos-Colorado river divide. This situation seemingly supports the +thesis that clines are maintained by some sort of parallel gradient in +ecological or geological conditions. It is notable that streams draining +the Edward's Plateau (inhabited by _guadalupensis_) differ in quantity +(more) and quality (especially CO_{3}^{--}, Ca^{++}, and Mg^{++} ions) +of their solutes, and probably pH (higher) from those farther east +(Hubbs, 1957:102). The gross difference in habitats mentioned above +(sandy, turbid, sluggish streams in the west _vs._ clear, swift streams +in the east) may affect the differentiation recognizable in the +_spinifer-hartwegi_ cline. + + +Daily and Seasonal Activity + + +_Diurnal Habits_ + +Softshells bask on débris in the water or on banks close to the water; +basking presumably raises the bodily temperature. In general in the +southeastern and southwestern United States, I have seen softshells +basking only rarely but once saw six at one time close together on logs +in Bowie Creek, Hattiesburg, Mississippi (species undetermined). Surface +(1908:122) saw _spinifer_ in rows on rocks or logs in tributaries of the +Ohio River. Duellman and Schwartz (1958:271-72) stated that _ferox_ +basks on banks or beds of aquatic vegetation. Deckert (1918:31) +mentioned large _ferox_ "sunning in shallow water at edge of pond." +Minton (1944:447) wrote that _muticus_ and _spinifer_ sun on steep mud +banks (Wabash River). Cahn (1937:180) stated that _muticus_ (in +Illinois) basks on banks at the water's edge but seldom on logs, and +suggests that _muticus_ is less prone to leave the water than +_spinifer_. According to Carr (1952:438), _muticus_ never basks on +logs or rocks. In Ohio, Conant (1951:159) mentioned _spinifer_ as +occasionally basking upon a log or rock, or sometimes on steep clay +banks of streams. On banks, quick escape is facilitated by directing the +head toward the water, thus eliminating the time that it would take to +turn around on land (Conant, _loc. cit._; Newman, 1906:129). Evermann +and Clark (1920:593) mentioned _spinifer_ as basking on sandy or grassy +shores, and large boulders. Muller (1921:181) wrote that _muticus_ basks +four to ten feet from the water's edge on gently sloping sand and mud +shores of small islands in the Mississippi River (near Fairport, Iowa). +Muller stated that basking usually occurs in the morning, up until 2 p. +m., and that beaches with a northern exposure were preferred; he +observed 37 turtles within a 50-foot stretch of beach. In captivity, +hatchlings bask on wire-mesh supports. + +I have frequently observed softshells floating at the surface of the +water, a habit previously mentioned by Surface (1908:122) and Pope +(1949:305, 311). Individuals of _Pseudemys_ and, to a lesser extent, +_Graptemys_ also float at the surface; those kinds of turtles and +softshells at least, often appear at the surface of the water, seemingly +as a result of an inquisitiveness, following repeated disturbances that +cause submergence. + +Newman (1906:131) described the active pursuit of food: "They crawl or +swim along the bottom, thrusting their snouts under stones and into +masses of aquatic vegetation, occasionally snapping up a crayfish or +larva that they have succeeded in dislodging. They do not tear up their +food, but swallow it whole, using the forefeet to assist in forcing it +down." Surface (1908:123) suggested that softshells may feed "upon +insects which may be found floating on the water," and I have had +captives take insects from the surface of the water. Carr (1940:107) +also wrote that _ferox_ and numerous gars in the Tamiami Canal, often at +the mouths of the tributary ditches, snap at each other furiously as +floating bits of food are washed in from the Everglades. Another habit +that has been mentioned as an aid in acquiring food (Breckenridge, +1944:186; Conant, 1951:156; Hudson, 1942:101) is burrowing just below +the surface in a soft bottom in shallow water, to ambush passing fish, +or other food. Presumably all kinds of softshells do this in both +shallow and deep water of lakes or rivers having a suitable substrate; +_spinifer_ and _muticus_ have been reported to burrow in shallow waters +(no observations in deep water) by Agassiz (1857:333), Cahn (1937:180, +189), Conant (1951:159) and Weed (1923:48). Marchand (_in_ Carr, +1952:417-19) noted that _ferox_ burrows in deep water, and mentioned +that in areas of bare white sand a group of fish invariably surrounds +them, and one can locate buried softshells by observing these particular +schools of fish. No mention was made of the turtles attempting to catch +the fish. Other associations of soft-shelled turtles and fish have been +described. Kirtland (_in_ DeKay, 1842:7) observed several large bass +that closely followed large numbers of turtles floating at the surface. +Newman (1906:131) reported the observations of fishermen in Lake +Maxinkuckee that large-mouth black bass stay not far away from swimming +softshells; the same author also mentioned the observations of Jacob +Reighard, who suggested that bass may be feeding upon minnows that he +noticed following softshells. Seemingly some sort of commensalistic +relationship exists whereby fish acquire food that is dislodged by +grubbing and scurrying of softshells. Probably food is pursued on +occasion from a buried position, but this habit probably is not executed +specifically for obtaining food. Newman (_op. cit._:129) was of the +opinion that burrowing in shallow water is a habit to facilitate +"warming up." + +Marchand (_loc. cit._) also wrote of other notable underwater +observations on _ferox_ in Florida. He commented on this turtle's +inquisitiveness in deep water and unconcern upon being touched or even +upon being handled to some degree. Calf-deep in soft mud, he noted a +turtle that "emerged from the mud of the bottom, headed up toward shore, +circled, and when about three feet above the bottom dived suddenly and +completely disappeared." Marchand wrote that some areas on the bottom +(Crystal Springs), which are rooted up by the burrowing of softshells, +are bare and soft, and assume a characteristic, easily recognized, +appearance. + +Cahn (1937:180, 189) stated that the burrowing process consists of +"flipping" the loose sand or silt over the back, whereas Conant +(1951:159) described the process as a rapid lateral movement of the +body. My observations of captives agree essentially with Conant's +observations. The initial movement, directed at a slight angle, is +principally with the forelegs although complemented by lateral movements +of the body. When the turtle is approximately half buried, it makes +rapid lateral movements of the body, which completely bury the turtle +and orient its body in a horizontal position. + + +_Behavior and Adaptations_ + +Some characteristics of softshells that are often mentioned in the +literature are: extreme shyness or wariness, ferociousness as captives, +dazzling speed and agility on land and in water, and great dependence on +aquatic environment. Certainly they are wary; and this wariness may +account, in part, for the scarcity of observations of basking, and +statements attesting to their great speed on land. To my mind, their +reported ferociousness and savage disposition as captives is overrated; +of the many softshells that I have collected, only a few attempted to +bite. The extensibility of their long neck does warrant more careful +handling than needs to be employed with other species. Holbrook (_in_ +Hay, 1892:145) even wrote that they "will sometime leap up and give a +loud hiss," and Newman (1906:130) wrote that "they hiss violently and +thrust out the head." Wright and Funkhouser (1915:120) reported a +captive _ferox_ that "could jump forward practically its own length." I +have been bitten by individuals of _Kinosternon_, _Sternothaerus_, +_Pseudemys_ and _Graptemys_, and cannot support the contention that +softshells are more prone to bite than those species, a view shared by +LeConte (_in_ DeKay, 1842:7); many softshells on initial capture will +tend to withdraw the head completely for a short time. Newman (_loc. +cit._) also wrote that recently captured specimens exude a thick, +yellow, semi-fluid resembling yolk of an egg from the inguinal glands; +the substance, however, is odorless but "undoubtedly homologous with the +emission of the inguinal glands of the musk and snapping tortoises." +Perhaps there is a difference in aggressiveness associated with +geographic location, the age of the turtle or individual temperament. + +Smith (1956:159), referring to _muticus_, wrote that they are the best +swimmers of all fresh-water turtles, and perhaps of any turtles. +Corresponding statements of other authors attesting to their speed and +agility (including _spinifer_ and _ferox_) in water and on land are +based principally on the published comments of Muller (1921:181), who +observed that females disturbed while laying eggs "about fifty feet from +water ... covered the distance faster than a man can run." Cahn +(1937:180) also stated that _muticus_ on a "level, unobstructed sand +beach ... can outrun a man," and (_op. cit._:181) can "capture fish with +ease"; Cahn supported the latter statement by relating his observation +of a _muticus_ that captured a small brook trout in a large tank. Smith +(_op. cit._:162) wrote that _spinifer_ is "said to overtake bass." +Doubtless they are good swimmers and they do scurry rapidly on land. + +Published statements relating to the strictly aquatic existence of +softshells especially _muticus_, are based on recognition of "its +drastic adaptations to aquatic existence" (Carr, 1952:428); these +adaptations presumably include pharyngeal respiration and the marked +depression of body form. Pharyngeal respiration was demonstrated for +_muticus_ and _spinifer_ (Gage, 1884; Gage and Gage, 1886), and was +considered the principal type of aquatic respiration (some dermal and +some cloacal) in _Trionyx spinifer asper_ by Dunson (1960). Cloacal +bursae (anal respiration) are lacking in trionychids (Smith and James, +1955:88). Accessory pharyngeal respiration is meaningful in light of the +information furnished by Agassiz (1857:282-83), who found that _Trionyx_ +has a smaller lung capacity (weight of body in ounces/capacity of lungs +in cubic inches = 16.9) than do some other genera (_Pseudemys_, 2.8; +_Testudo_, 2.7; _Terrapene_, 1.1); corresponding values for more aquatic +species were _Chelydra_, 9.3 and _Kinosternon_, 16.0. Cahn (1937:181), +however, wrote that he has demonstrated pharyngeal respiration in +individuals of _Pseudemys_, _Chrysemys_ and _Sternothaerus_, and Allen +and Neill (1950:13) suggested that it occurs in _Macroclemys_. More +conclusive data are required to detect a positive correlation between +small lung capacity, pharyngeal respiration, and degree of restriction +to an aquatic habitat. + +The depressed, soft-margined carapace of softshells has been mentioned +as an adaptation to facilitate burrowing in soft sand or mud, and more +suited for concealment than for speed in aquatic locomotion (Carr, +1952:429; Smith, 1956:162). Nielsen (1951:264-65), commented that in +various lotic invertebrates, dorsoventral flattening of the body was no +commoner than in lentic invertebrates; he wrote that a dorsoventral +flattening is a disadvantage to an animal in a strong current and is an +adaptation "probably ... not to withstand the current directly, but to +avoid it by seeking shelter in narrow crevices." Probably another aid to +concealment, mentioned by Williams and McDowell (1952:272), is the +plastral hinge. + +Concealment of softshells is not enhanced by growths of algae on the +carapace. Proctor (1958:637-38) reported that the common, epizoöphytic +alga of chelonians, _Basicladia_, has never been reported from +_Trionyx_; the same author recorded a large amount of filamentous algae, +principally _Stigeoclonium_, but the algae could be easily wiped from +the turtle, and Vinyard (1955:64) recorded an alga, _Dermatophyton +radians_, attached to the skin of the legs of _Trionyx_. I noted a small +patch of greenish scum growing near the insertion of the neck on a +softshell (_spinifer_ from Lake Texoma); cursory examination by Dr. R. +H. Thompson, disclosed one of the colonial ciliate protozoans +(resembling _Opercularia_) with enmeshed green or blue-green algae. +Evermann and Clark (1920:592) mention a _spinifer_ from Lake +Maxinkuckee, Indiana, having a growth of _Opercularia_, covering the +plastron. + + +_Movement_ + +The reported proclivity of softshells for a strictly aquatic existence +has been over-emphasized; they are no more confined to aquatic habitats +than some chelydrids (including kinosternids). In fact, there is a +general parallel in habits between members of the two families, namely, +a tendency toward a bottom-dwelling existence, and a burrowing habit. +The alligator snapping turtle (_Macroclemys_) is probably the most +aquatic fresh-water turtle in the United States. The common snapping +turtle and some kinosternids are known to migrate overland. Kinosternids +and trionychids bask frequently, and trionychids have been observed +moving overland. Cox (1894:50) reported a _spinifer_ attempting to climb +a narrowly-stepped, 12-foot dam on Mud Creek at Ravenna, Nebraska; the +turtle failed after repeated struggles, once reaching a height four +inches shy of the brim before tumbling back into the water. Duellman and +Schwartz (1958:271) commented that adults of _ferox_ are often seen on +roads bordering canals, and informants have told me verbally of similar +observations. Conant (1930:61) reported an individual of _ferox_ that +was "... walking across the main street in Venice [Sarasota County, +Florida]." Softshells will travel overland in search for suitable +nesting sites; Newman (1906:130) wrote that _spinifer_ will climb "steep +railway embankments with considerable ease, in order to reach a sand pit +some fifty yards from the water." + +From an analysis of species-composition of large reservoirs and lakes +and their adjacent smaller ponds in southern Illinois, Cagle (1942:162) +concluded that softshells "travel overland far less often than do ..." +other species, but that they are "probably the first to move as the +water level falls." On the basis of further observations in the same +region, Cagle (1944:15) wrote that softshells rarely move overland, and +once trapped in a pool of water, they bury themselves and remain there. +He related instances of several individuals having been dug from dried +mud where the last remnants of a water pool had evaporated and he +concluded that the home range is probably confined to one body of water. +That fluctuations in water level affect the movement of softshells is +suggested by Mr. William E. Brode's comment that a commercial fisherman +trapped numerous softshells in the Pearl River, south of Monticello, +Mississippi, in unbaited hoop-nets in late May and June when the water +level was receding after heavy rains. + +The meager data available concerning the aquatic movements of softshells +indicate that individuals wander but little. Breckenridge (1955:6, +table 1) found that among 30 recaptured turtles that had been marked, +the greatest distance traveled was 600 yards over a two-year interval; +after a three-month interval one originally captured 30 miles distant, +moved only 200 yards. The statement of a professional turtle trapper +mentioned by Breckenridge (_loc. cit._) and data previously presented +(see page 436), to the effect that over-trapping results in increasingly +diminished returns, tends to support the idea that there is little +aquatic movement in soft-shelled turtles. + +Breckenridge (_loc. cit._) mentioned methods of marking softshells and +found that notching the edge of the carapace with a leather punch was +satisfactory; the notches healed but were discernible as shallow +sinuses. The same author mentioned a tattooing device (mentioned also by +Cagle, 1939:171), but no turtles so marked were ever recognized as +recovered. Tagging with a radioactive isotope and detection with +suitable instruments should prove applicable to turtles (see Karlstrom, +1957). + + +_Nocturnal Habits_ + +Anderson (1958:212) wrote that hatchlings (_muticus_) leave nests within +the first three hours after sunset, and are active on the surface of the +sand at night. Muller (1921:183) reported hatchlings (_muticus_) leaving +nests at night or early in the morning. Lagler (1954) stated that +_spinifer_ is nocturnal. To my knowledge there are no other published +statements concerning nocturnal activity of soft-shelled turtles. I have +noted them at night on only four different occasions. In two instances +(Clear Fork Brazos River, Texas, and Lake Concordia, Louisiana), the +turtles were resting immediately below the surface of the water on +submerged branches, as one would expect _Pseudemys_ and _Graptemys_ to +do. Another individual was seen swimming near the surface (Ocmulgee +River, 1-1/2 mi. S Jacksonville, Georgia); this observation possibly +represents nocturnal activity, or inquisitiveness owing to the +disturbances caused by the motor of the boat and/or our head lights. A +final observation tends to support the view of nocturnal habits. My +field notes record at least four softshells collected by hand, and a few +other seen in a shallow (approximately four feet deep), quiet, clear +water side channel of the White River (Cotter, Arkansas); the turtles +were seen resting and slowly moving on the bottom or swimming. + + +_Seasonal Occurrence_ + +The length of the season of activity increases with decrease in +latitude. Aquatic species in general have longer periods of activity +than terrestrial species at the same northern temperate latitudes. The +southernmost populations of all species of softshells may be active +throughout the year, assuming temperature to be the limiting factor. + +There are few published statements relative to the length of the annual +period of activity; all records refer to _spinifer_. In Lake +Maxinkuckee, northern Indiana, Newman (1906:128) wrote that individuals +were first seen in early April on the lake shore in a weak condition +with neck and legs extended, and were easily captured. Lesueur +(1827:262) wrote that _spinifer_ in Indiana appears toward the end of +April. Observations of Evermann and Clark (1920:592) in Lake +Maxinkuckee, and Butler (1894:224) in east central Indiana concurred in +finding that of all kinds of turtles there, softshells appeared last in +spring and disappeared first in fall. Evermann and Clark found small +softshells, benumbed or dead, along the shore as early as March 18 and +also late in fall. The earliest observation for large softshells was +April 29, and the latest was September 7; Butler found that these +turtles rarely appear before April 15 and sometimes not until May 1. +Cahn (1937:191) stated that softshells in Illinois hibernate toward the +end of October and emerge in May or the latter part of April; the same +author mentioned that in southern Illinois the species might remain +sluggishly active all winter. In Ohio, Conant (1951:160) wrote that +individuals were collected every month from March to October, and one +was even taken in December, 1929, in northwestern Ohio. Wright (1919:8) +mentioned observing softshells on April 20 and September 20 (presumably +these were the earliest and latest observations of them) in Monroe and +Wayne counties, New York. Blatchley (1891:34) listed dates of early and +late activity as March 19 and December 11 for Vigo County, Indiana. +Webster (1936:22) recorded the earliest and latest dates of collection +of _spinifer_ in central Oklahoma as June 10 and November 8. + +Moore and Rigney (1942:80) found an individual of _muticus_ under six +inches of ice in water about one foot deep on January 31, 1940 (Cimarron +River, Payne County, Oklahoma). + +The published information suggests that the length of the normal annual +period of activity of _spinifer_ in latitudes of about 40° and 43° is +approximately five months, from April into September, depending upon the +weather. There are numerous published statements to the effect that the +period of hibernation is passed under a shallow covering of mud in deep +water. Evermann and Clark (_op. cit._: 593) found a softshell +(presumably in a quiescent state) on September 6 that was "buried up to +its eyes in mud at the edge of Lost Lake." Softshells possibly hibernate +in shallow water or in soft mud flats. Conant (_loc. cit._) found that +captives would not hibernate in a pond in a zoo having a bottom of +leaves. + + +Food Habits + +Previous authors, most of whom allude to published statements preceding +their own, characterize soft-shelled turtles as carnivorous and mention +such food items as crawfish, insects, worms, snails, clams, frogs, +tadpoles, fish, and occasional vegetable matter. Stockwell (1878:403) +wrote that the relative lengths of portions of the digestive tract +indicate "a purely carnivorous diet." + +In an examination of the contents of 11 stomachs of _spinifer_ from +Michigan, Lagler (1943:304) found that crawfish (47%) and insects +(52%), principally burrowing mayfly naiads (_Hexagenia_), and +dragonfly naiads, comprised the bulk of the diet with cryptogams, +vegetable débris, snails and fish remains present in small amounts. +Breckenridge (1944:186) wrote that 18 specimens of _spinifer_ in +Minnesota contained 44 per cent crawfish, 29 per cent aquatic insects, +8 per cent fish, and 19 per cent unidentified material. Surface +(1908:123) found crawfish in the only two stomachs of specimens he +examined from Pennsylvania. Penn (1950) summarized the results of +those authors, and estimated that crawfishes comprised 58 per cent +(46% by volume) of the diet of softshells. In Indiana, three stomachs +examined by Newman (1906:131) in late June contained: 1) nine +crawfish, 2) four crawfish, 22 dragonfly naiads, 3) nine dragonfly +naiads, few plant buds. Neill (1951a:765) found crawfishes in the +stomachs of five _spinifer_ from the Savannah River, Georgia. Evermann +and Clark (1920:595) wrote that _spinifer_ in Lake Maxinkuckee feeds +principally on crawfishes. Shockley (1949:257) mentioned bottom +organisms and small fishes as food. Clark and Southall (1920:16) +stated that "Its principal food, to judge from a few specimens +examined, consists of crayfishes." + +Cahn (1937:183) wrote that the food of _muticus_ in Illinois consists +principally of crawfish, fish, frogs, tadpoles, larger insect larvae +and nymphs, and aquatic mollusks. The kinds of fish eaten were +_Notropis heterolepis_, _N. spilopterus_, _N. hudsonius_, _Lepomis +machrochirus_, _Morone chrysops_, _Perca flavescens_, _Catostomus +commersonnii_, and _Hypentelium nigricans_; Cahn (_loc. cit._) also +stated that the mollusks eaten by _muticus_ are both gastropods and +small, thin-shelled bivalves. In regard to the feeding habits of +_spinifer_ in Illinois, Cahn (_op. cit._:193) listed the following +items in decreasing order of abundance as revealed by examinations of +stomachs: crawfish, minnows, fry of larger fish, frogs, tadpoles, +earthworms, insects (often beetles), and mollusca (_Pisidium_, +_Viviparus_, planorbids). The kinds of fish mentioned were: _Notropis +heterodon_, _N. heterolepis_, _N. hudsonius_, _Catostomus +commersonnii_, _Lepomis humilis_, _L. macrochirus_, _Semotilus +atromaculatus_, _Notemigonus crysoleucas_, _Umbra limi_, and +_Micropterus salmoides_. Cahn (_loc. cit._) also found the remains of +a six-inch brook trout (_Salvelinus_) in the stomach of a 13-inch +_spinifer_ from Wisconsin. + +Agassiz (1857:399) found larvae of neuropterous insects in the stomach +of one specimen of _muticus_, and fragments of _Anodonta_ and +_Paludina_ (= _Campeloma_) in the stomach of one _ferox_. The expanded +crushing surfaces of the jaws in some large individuals of _ferox_ may +be an adaptation to mollusc-feeding (Schmidt and Inger, 1957:36). +Surface (1908:123) found _spinifer_ to have fragments of beetles in +one of two specimens examined, and large quantities of corn in another +from Ohio. Webb and Legler (1960:27) reported 23 chrysomelid beetle +larvae (_Donacia_) in one specimen of _T. ater_. Evermann and Clark +(1920:595) reported several _spinifer_ taken on hooks baited with +grasshoppers in water 14 feet deep in Lake Maxinkuckee, Indiana. Hay +(1892:144) wrote of _muticus_ that "If there are potatoes growing near +the water the turtles find their way to them and devour the stems, of +which they are very fond." Wright and Funkhouser (1915:123) stated +that young _ferox_ in the Okefinokee Swamp feed on fish and frogs, and +according to the natives, larger specimens take waterfowl, a statement +that Smith (1956:159) was probably reiterating when he mentioned that +the diet included "perhaps young birds." Parker (1939:88) wrote that +of two _spinifer_ from Reelfoot Lake, Tennessee, one contained +coleopteran remains, and the other an aquatic beetle and two large +tipulid larvae. Wied-Neuwied (1865:54) wrote that Lesueur found worms, +snails, remains of _Paludina_ (= _Campeloma_), fruits and even hard +nuts in stomachs of _muticus_. + +Holbrook (_in_ Hay, 1892:145) mentioned that _spinifer_ feeds on fish +and such reptiles as it can secure. There are no published statements +known to me that report reptiles in the diet of American softshells. +Carr (1952:425) erroneously cited Strecker (1927:9) and attributed "a +young lined snake" to the diet of _T. s. emoryi_; Strecker, however, +referred to _Kinosternon flavescens_. In conjunction with raising +softshells on turtle farms, Mitsukuri (1905:261) mentioned that first +and second year-old turtles (_Trionyx sinensis_) must be transferred +to separate ponds or they will be eaten by adults; perhaps +corresponding cannibalistic tendencies exist in confined, natural +habitats in American softshells. + +Captives eat essentially the same things that free-living individuals +do, plus scraps of meat (Strecker, 1927:9; Gloyd, 1928:135; Pope, +1949; Conant, 1951:156, 160). Lagler (1943:303) mentioned a young +_spinifer_ that fed on water fleas (_Daphnia_) and canned fish. Conant +(_op. cit._:160) wrote that no captive was observed to take vegetable +matter. + +Food, mostly in intestines, of two adult females of _T. s. emoryi_ +collected on June 12-14, 1959, from the Río Grande at Lajitas, +Brewster County, Texas, was examined. One female, KU 51961, contained +little food and mostly plant fragments; because the stomach or +intestine was not full of plant fragments, this food probably was +ingested incidentally to the few insects present. Another female, KU +51955, contained insects, which were identified by Dr. George W. +Byers, Department of Entomology, University of Kansas, as follows: 1) +Coleoptera, Dryopidae, genus _Helichus_, most numerous, 350 to 400 +individuals; 2) Coleoptera, Scarabaeidae, genus _Phyllophaga_, one +individual; 3) Odonata, Coenagrionidae, fragments, probably one +individual; 4) Hymenoptera, Sphecidae, subfamily Bembicinae, one +individual; 5) Ephemeroptera; fragments of naiad; and 6) a few plant +seeds, pieces of slender roots, weed stems and a couple of fragments +of tree bark. The scarab and wasp probably fell into the water and +were eaten. + + TABLE 6. Kinds of Insects Found in Stomachs and Intestines of 11 + Specimens of Trionyx m. muticus (Eight Adult Males and Three + Immature Females, 9.0 to 12.5 cm. in Plastral Length) From Douglas + County, Kansas. Frequency of Occurrence (Approximate Number of + Individual Insects/Number of Stomachs in Which Found) Is Given for + Each Item Listed. Fragments of Insects Represent Adults Unless + Otherwise Noted. + + ==========================================================+=========== + FOOD ITEM | Frequency + ----------------------------------------------------------+----------- + Orthoptera | + Locustidae | 1 + | + Ephemeroptera | + Unknown (naiad) | 1 + | + Odonata | + Anisoptera (naiad) | 3/3 + Zygoptera (naiad) | 4/2 + | + Plecoptera | + Unknown (naiad) | 2/1 + | + Homoptera | + Cicadellidae | 20/7 + | + Hemiptera | + Lygaeidae | 1 + | + Neuroptera | + Corydalidae (_Corydalis_ larva) | 1 + | + Trichoptera | + Hydropsychidae? (incl. 18 larvae and 4 pupae) | 23/9 + Unknown (incl. 1 larva) | 4/4 + | + Lepidoptera | + Noctuidae? (larvae) | 2/1 + Pyralidoidea (larva) | 1 + Unknown | 1 + | + Coleoptera | + Carabidae (incl. 1 larva) | 3/3 + Cerambycidae? | 1 + Chrysomelidae | 1 + Cicindelidae (larva) | 1 + Elateridae (larva) | 1 + Hydrophilidae? (larvae) | 4/2 + Scarabaeidae (incl. _Phyllophaga_) | 9/6 + | + Diptera | + Anthomyiidae | 1 + Asilidae | 1 + Bibionidae (_Bibio_) | 5/2 + Calliphoridae (puparium) | 1 + Empididae | 1 + Mycetophilidae | 1 + Tipulidae (incl. _Tipula bicornis_ and _T. triplex_?) | 9/4 + Unknown (5 muscoid, 3 acalyptrate, and 1 cyclorrhaphous | + types) | 9/4 + | + Hymenoptera | + Apoidea | 1 + Formicidae (incl. _Camponotus_) | 11/4 + Ichneumonidae (one questionable) | 4/3 + Tenthredinidae | 1 + Unknown (small wasps) | 3/2 + ----------------------------------------------------------+----------- + +Food from the digestive tracts of 11 specimens of _T. m. muticus_ from +the Kansas River at Lawrence, Douglas County, Kansas, were examined +(Table 6). The turtles (KU 55296-306, eight adult males and three +immature females, ranging in plastral length from 9.0 to 12.5 cm.) +were collected in June, 1958, by Mr. Robert R. Patterson. All turtles +were caught on hook and line in a period of about four or five hours +at dusk. Patterson frequently fished below the bridge at Lawrence and +observed that heads of softshells were often seen there about dusk and +that the turtles seemed to prefer a rather shallow, quiet-water area +of swirls and eddies for feeding. The stomachs, and to a lesser +degree, the intestines, were nearly full. Some turtles contained plant +fragments, principally elm seeds. The kinds of food in this sample +were also identified by Dr. Byers and were mostly insects, the most +frequent item being trichopterans; many of the insects eaten +undoubtedly fell into the water. The remains of spiders were found in +four stomachs and crawfish fragments in five. + +Stomachs of two adults of _muticus_ from Lake Texoma, Oklahoma, were +opened. The stomach of one (OU 27593) was full of naiads of the +burrowing mayfly _Hexagenia_; that of the other female (OU 27594) +contained exoskeletal remains of crawfish. The two specimens were +drowned in gill nets between the hours of 11 a. m. and 7 p. m., on +July 10, 1954; the intact condition of the mayfly naiads indicated +recent feeding. + +The species of American softshells are mainly carnivorous. The presence +of vegetable matter (mentioned in previous paragraphs) in the digestive +tracts of many specimens and True's statement (1893:152) that +soft-shelled turtles include a variety of vegetable matter in their food +indicates omnivorous habits. Duellman and Schwartz (1958:272) stated +that _ferox_ is omnivorous and Carr (1952:430) made a similar statement +for _spinifer_. The diet seems to be determined by the food supply +available, which may vary seasonally or with adverse conditions such as +flooding; under normal environmental conditions, however, vegetable +matter probably is ingested incidentally to other food. There is no +indication of a preference in food habits according to species and +subspecies. Most of the food seems to be obtained by active foraging +that is triggered primarily by movement of the prey; the sense of smell +is probably secondary. + + +Reproduction + + +_Size of males at Sexual Maturity_ + +Elsewhere (1956:121) I have shown that males of _spinifer_ from Lake +Texoma, Oklahoma, and scattered localities in Texas and Louisiana +are sexually mature when they reach a plastral length of 9.0-10.0 +centimeters. Adult males have distinct, convoluted, non-pigmented vasa +deferentia and elongate testes, the maximal measurements of which are +about 10 by 30 millimeters. Testes of hatchlings are approximately 4.0 +by 0.4 millimeters (TU 13698.12, plastral length 3.2 cm., measured with +ocular micrometer). I am not aware of seasonal changes in size of the +testes. + +In reading the discussion that follows, it is well to remember that +males having the cloaca extending beyond the posterior edge of the +carapace are regarded as sexually mature. As an indication of geographic +variation in _spinifer_, I have listed the measurements of the 10 +smallest males for only those subspecies of which there are numerous +records (Table 7). Corresponding data for _T. muticus muticus_ are also +listed for comparison. + + TABLE 7. Size at Sexual Maturity of the 10 Smallest Males of T. m. + muticus and Selected Subspecies of T. spinifer. The Extremes + Precede the Mean (in Parentheses). + + ========================+======================= + SPECIES AND SUBSPECIES | Plastral length (cm.) + ------------------------+----------------------- + _T. s. spinifer_ | 8.8-10.3 (9.6) + _T. s. hartwegi_ | 9.6-10.5 (10.2) + _T. s. pallidus_ | 9.1-11.2 (10.5) + _T. s. guadalupensis_ | 9.3-10.8 (10.1) + _T. s. emoryi_ | 8.2-9.0 (8.8) + _T. m. muticus_ | 8.2-9.2 (8.7) + ------------------------+----------------------- + +The data indicate that the size at which sexual maturity is attained in +_emoryi_ (about 8.0-9.0 cm.) is less than in any other subspecies of _T. +spinifer_ (about 9.0-10.0 cm.), and, more importantly, corresponds to +that of _T. m. muticus_. Although the mean for _T. s. spinifer_ is +slightly less than in the remaining subspecies, I doubt that there is +any significant difference according to subspecies in the size at which +sexual maturity is attained in the subspecies _spinifer_, _hartwegi_, +_asper_, _pallidus_ and _guadalupensis_. The corresponding size in _T. +m. muticus_ and _T. s. emoryi_ heightens the morphological resemblance +between these forms. The only sexually mature male of _T. ater_, which +morphologically resembles _emoryi_ and _muticus_, is 9.5 centimeters in +plastral length. I do not know the size at which _T. ferox_ attains +sexual maturity. The smallest sexually mature individual examined by me +was 12.0 centimeters; probably _ferox_ attains sexual maturity at a +larger size than _spinifer_ or _muticus_. The relative size of +attainment of sexual maturity in _ferox_, _spinifer_, and _muticus_ +corresponds to the maximum size of the three species; _ferox_ is the +largest species and _muticus_ is the smallest (Table 2). + + +_Size of Females at Sexual Maturity_ + +Breckenridge (1955:6) wrote that the development of the mottled pattern +"undoubtedly indicates a stage in the attainment of sexual maturity"; I +have mentioned (1956:121) that the mottled pattern is apparent on +females before sexual maturity is attained. To my knowledge females have +no external characters which appear at the time of attainment of sexual +maturity. + +Sexually mature individuals of _ferox_ have been described in various +terms: 31-1/4 pounds (Goff and Goff, 1935:156); six pounds, lengths of +carapace 10-1/2 and 13 inches (Hamilton, 1947:209); greatest width of +head 3-1/2 inches (Wright and Funkhouser, 1915:120). A 10-1/2 inch +carapace presumably represents the smallest turtle and corresponds to a +plastron approximately 22.0 centimeters in length. There is no other +information available concerning size at sexual maturity in _T. ferox_. + +There is little published information concerning the size at sexual +maturity in _T. spinifer_. Cahn (1937:193) wrote that _spinifer_ in +Illinois "must attain a carapace length of about 24 centimeters +[plastral length approximately 18.0 cm.] before the females become +sexually mature"; this statement is the basis for Smith's mentioning a +length of 9-1/2 inches (1956:162). Evermann and Clark (1920:595) +recorded the lengths of carapace of some females (presumably all adult) +from Lake Maxinkuckee, Indiana, as 11, 11-3/4, 12-1/2, and 13 inches; +the smallest measurement corresponds to a plastral length of +approximately 21.0 centimeters. + +The data concerning reproduction presented in succeeding paragraphs is +based principally upon examinations of turtles in the TU collections; I +am indebted to Dr. Fred R. Cagle for permission to dissect these +turtles. Females are regarded as sexually mature when they have oviducal +eggs or corpora lutea or ovarian follicles exceeding 15 millimeters +in diameter. Hatchlings of _spinifer_ have ovaries that measure +approximately 6.0 × 0.3 millimeters, and straight oviducts 0.2 +millimeters in width (TU 5988, plastral length 3.5 cm. measured with +ocular micrometer). In the size at which sexual maturity is attained +there seems to be much individual variation as well as geographic +variation. + +Females of _T. s. emoryi_ from the Río Grande in the Big Bend region +of Texas are sexually mature when the plastron is approximately 16.0 +centimeters (16.2 cm., KU 51960), and are the smallest adult females +of _spinifer_ that I have seen; these females are representative of +the population from which the smallest adult males of _spinifer_ are +known and which is unique in showing sexual differences in coloration. +A female (TU 3697), having a plastral length of 16.0 centimeters, +which was obtained in the Río Grande near Eagle Pass, Texas, in +mid-July, is immature; the ovaries are compact having the largest +follicles 2.5 millimeters in diameter, and the oviduct is wrinkled and +convoluted but only six millimeters wide. Of three females of _emoryi_ +from the Pecos River, Terrell County, Texas, having plastrons 17.4, +18.3 and 18.8 centimeters in length and obtained on June 11, the +largest and smallest are immature, and internally resemble TU 3697. TU +14453.2 (18.3 cm.) is sexually mature having large corpora lutea and +enlarged ovarian follicles. KU 53754, from the Río Salado in central +Coahuila, México, having corpora lutea and a plastral length of 20.3 +centimeters, is sexually mature. + +Females of _T. s. guadalupensis_, measuring 14.5, 15.7, 16.3, 16.5, +16.8, 17.0, 19.0, and 20.0 centimeters in plastral length and obtained +from June to September, are immature. The female measuring 19.0 +centimeters indicates the approach of sexual maturity in having +swollen and convoluted oviducts seven to ten millimeters in width, but +compact ovaries having the largest follicles 4.0 millimeters. The +other _guadalupensis_ whose measurements are given above have oviducts +that do not exceed four millimeters in width, and ovarian follicles +that do not exceed two millimeters in diameter. TU 10187, obtained in +July, plastral length 19.5 centimeters, is sexually mature having +corpora lutea and enlarged follicles. Two other _guadalupensis_, 21.5 +and 22.0 centimeters (Pl. 12, top), having ovaries with enlarged +ovarian follicles (the largest in one, only 11 mm.) are considered +sexually mature. + +Concerning the subspecies _pallidus_, females (all collected in June +or July) measuring 15.7, 16.3, 17.3, 17.5, 18.7, 19.5, 20.8 and 21.3 +centimeters in plastral length are immature having solid, compact +ovaries with the largest follicles not exceeding two millimeters in +diameter; oviducts are straight not exceeding three millimeters in +greatest width, except those turtles measuring 17.3 and 21.3 +centimeters in which the oviducts are swollen and convoluted and, +respectively, five and eight millimeters in greatest width. The +smallest sexually mature _pallidus_ is 19.8 centimeters in length; +recorded lengths of other adult females are 23.5, 26.8 and 30.5 +centimeters. + +Of especial interest are three large female _pallidus_, measuring +24.8, 27.5, and 28.0 centimeters, which appear to be immature; two of +these (TU 13303-04) are from the Sabine River, collected in July, and +the other specimen is without data (presumably from the Sabine River). +The oviducts are large, swollen and convoluted, resembling those in +sexually mature individuals. The ovaries, however, are relatively +solid and compact having approximate measurements of 125 × 6 +millimeters (TU 13303) and 85 × 10 millimeters (TU 13304), and +follicles not exceeding five millimeters in diameter. + +Females of _spinifer_ from the lower Mississippi Valley of Louisiana +having plastral lengths of 15.0, 15.5, 16.7, 17.5, 18.0, 19.5, 20.0, +20.4, and 20.8 centimeters are considered immature; the ovaries are +compact and solid having follicles not exceeding three millimeters in +diameter, and the oviducts, swollen and convoluted in the larger +individuals, do not exceed six millimeters in width. The ovaries of +the specimen 19.5 centimeters in length mentioned immediately above +had been removed prior to my examination; the oviducts, however, were +relatively straight and only five millimeters in width. Three females +23.0, 25.5, and 25.8 centimeters in length are sexually mature. TU +5518, measuring 21.5 centimeters in length and obtained in June, +indicates the onset of sexual maturity in having large convoluted +oviducts, but the ovaries are solid, compact, measuring 85 × 13 +millimeters, and the largest follicles are only 4.5 millimeters. A +larger turtle (TU 13080), 24.5 centimeters, obtained in July, has +juvenal ovaries (largest follicles five mm.); the oviducts are +enlarged and convoluted as in adult females. + +Of two _T. s. asper_ collected from the Escambia River in June and +July, one 18.0 centimeters in plastral length is immature, whereas the +other, 27.0 centimeters long, is adult. A female _T. s. hartwegi_, +measuring 20.7 centimeters, is adult having enlarged follicles and +corpora lutea (TTC 719, Pl. 36, bottom). + +In summary, females of all subspecies of _spinifer_, except some +_emoryi_, may be sexually mature when the plastron is 18.0 to 20.0 +centimeters in length; probably all physiologically normal females are +adult when 22.0 centimeters long. In general, females are sexually +mature at a plastral length of approximately 20.0 centimeters, a +measurement that corresponds to a length of carapace of approximately +28.0 centimeters or about 11 inches. Females representative of that +population of _emoryi_ inhabiting the Río Conchos and the Río Grande +in the Big Bend region of Texas are adult when the plastron is +approximately 16.0 centimeters in length, and are thus the smallest +sexually mature females of the species _spinifer_. Oviducts are large +(at least eight mm. in width, undistended), swollen and convoluted prior +to the first ovulation. + +Of interest are the large females (for example, TU 13303, plastral +length 28.0 cm.) that seemingly have immature, relatively small, ovaries +(the oviducts are large and convoluted as in adult females). Possibly +such ovaries represent a regression and are in senile turtles, but I am +inclined to believe that the development of these ovaries has been +arrested probably owing to hormonal unbalance, and that they have never +been functional. + +The size of adult females of _T. ater_ is unknown but probably +approximates that of _T. spinifer_ or is slightly less. Females of +_ater_ 15.5 and 17.2 centimeters in length are immature; the largest +female, the holotype, is 18.3 centimeters in length, and was not +dissected. + +Females of _T. muticus_ are sexually mature when smaller than _T. +spinifer_. Two turtles, 13.8 and 14.0 centimeters in length, have large +convoluted oviducts about 10 millimeters in width and ovarian follicles +nine to twelve millimeters in diameter, and seem to be near sexual +maturity. The smallest sexually mature female (subspecies _muticus_) is +TU 14436, measuring 14.4 centimeters in plastral length and having +oviducal eggs. Recorded lengths of other adult females are 16.3, 16.5, +17.2 (subspecies _muticus_), and 18.0 centimeters (subspecies +_calvatus_). Two females having plastral lengths of 17.5 (subspecies +_muticus_) and 16.0 centimeters (subspecies _calvatus_) seem sexually +immature. These turtles collected in April and May have ovarian +follicles not exceeding three millimeters in diameter. + + +_Sexual Activity_ + +Observations by Mitsukuri (1905:263), Conant (1951:160) and Legler +(1955:98), constitute the extent of our knowledge concerning courtship +and copulation. Legler observed a male _spinifer_ and a female _muticus_ +in captivity; the male was the aggressor, following at the rear or above +the female, and at times nipping at the anterior part of her carapace. +During these movements, the posterior edge of the female's carapace was +turned up slightly whereas that of the male was turned down; the turtles +frequently surfaced to breathe. Occasionally the female followed the +male. On the bottom the male crawled onto the female's carapace from the +rear, remaining in a somewhat posterior position as described by Conant +(_loc. cit._), and seemingly not clasping the female with his feet. +Copulation probably occurs in this position; Mitsukuri (_loc. cit._) +mentioned that copulation in _Trionyx sinensis_ occurs at the surface of +the water. The male remains in the coital position for approximately 15 +seconds and then slowly drifts to one side and swims away. Legler +observed five coital unions in one-half hour, each preceded by courting +movements. + +Legler's observations indicate that the courtship patterns of _muticus_ +and _spinifer_ are similar, and that interspecific matings are possible. +I have not noted any hybrid. + +Risley (1933:689) mentioned differential movements of the sexes of +_Sternothaerus odoratus_ in conjunction with the breeding cycle. Such +movements are revealed by trapping procedures that yield deviations from +the expected 1:1 sex ratio. That differential sexual movements probably +occur in _Trionyx_ is indicated by my trapping 17 males in a group of 19 +_spinifer_ in hoop-nets in Lake Texoma in the period June 14-July 12, +1954. On June 24-26, 1959, a field party from the University of Kansas +collected 15 softshells in hoop-nets at the mouth of the Río San Pedro, +near Meoquí, Chihuahua; all turtles were males. On June 17-18, 1959, the +same expedition trapped 11 males in a group of 13 turtles in the Río +Conchos, near Ojinaga, Chihuahua. Earlier, June 12-14, 1959, 39 +softshells were trapped in the Río Grande near Lajitas, Brewster County, +Texas. Of these turtles, however, 19 were adult males and 20 were +females; eight females were adult (sexually mature) all having oviducal +eggs (Fig. 23). One of the two females from Ojinaga, KU 51174, is +sexually mature (plastral length, 16.5 cm.) having oviducal eggs; the +other is immature (plastral length, 8.0 cm.). The only softshell taken +on June 21, 1959, 8 mi. N and 16 mi. W Ojinaga, KU 51173 (plastral +length, 16.3 cm.) is a female having oviducal eggs. The two females from +Lake Texoma are immature (plastral lengths, 9.8 and 12.4 cm.). + +The results of trapping may indicate that females frequent shallow water +for a short time before the period of deposition of eggs, but disperse +to deep water after such periods or between them. The movements of +immature females probably approximate those of adult males; the absence +of immature females in the Meoquí series, and near absence (only one) in +the Ojinaga series perhaps is due to fortuitous collecting methods or to +slightly different diurnal movements between adult males and immature +females. Females approaching sexual maturity and those sexually mature +but not having oviducal eggs ready for deposition possibly remain +relatively sedentary in deep water; such females possibly represent +those absent in the 13.0-15.9 size group (Fig. 23). Certainly, factors +other than those pertaining to egg deposition may cause mature egg-laden +females to live in shallow water, or explain the deviations from the +expected 1:1 ratio. + + [Illustration: FIG. 23. Size distribution of 39 _Trionyx spinifer + emoryi_ (19 males and 20 females) collected in the period June 12 + through June 14, 1959, from the Río Grande, near Lajitas, Brewster + County, Texas. Solid squares represent sexually mature specimens. + Females approaching sexual maturity or those not ready for egg + deposition (13.0-15.9 cm. size group) are possibly sedentary in + deep water.] + +One of the immature softshells (KU 51979, plastral length, 9.7 cm.) of +the series from Lajitas is considered to be a female. It combines +characteristics of both sexes. It resembles a male in having a carapace +gritty to the touch, in having prominent white dots posteriorly and in +not having a faint mottled and blotched pattern as do females of the +same size. The postocular and postlabial markings are mostly yellow +(female), but a small patch of the postocular stripe near the junction +with the pale ventral coloration laterally is tinted with orange (male); +the morphological characters and secondary sexual difference in +coloration of this series of softshells has been mentioned on page 512. +The tail is short and pyramidal resembling that of a female. Internally, +there are a pair of ovaries and oviducts; KU 51979 is functionally a +female. An over-production of androgens probably is responsible for the +external masculine characteristics (orange color, gritty carapace and +absence of mottling on carapace). + + +_Deposition of Eggs_ + +Concerning _T. ferox_, Wright and Funkhouser (1915:122-23) wrote that +deposition of eggs occurred in June and July in the Okefinokee Swamp +on the sandy parts of the islands or in sandy fields in places exposed +to the direct rays of the sun. The same authors recorded a gravid +female taken on June 22 (_op. cit._:120), and a nest with eggs on June +26. Harper (1926:415) reported egg-laying in June in the Okefinokee +Swamp. Goff and Goff (1935:156) found a female in search of a nesting +site crawling toward a cleared area within a hammock at 11 a. m. on +May 19, about 25 yards from the western shore of Lake Griffin, +Florida. Carr (1940:107) stated that eggs in Florida "are laid from +March to July 10. One individual laid her eggs on a block of ice which +we had buried in the sand." Hamilton (1947:209) observed deposition of +eggs near Fort Myers, Florida, in "a sandy roadbed slightly above the +cypress swamp and ditch levels on either side of the road." ... either +in ... "the ruts formed by cars or the slope of the roadbed"; dates of +deposition of eggs recorded are March 30 at 11 a. m. in bright sun, +and March 31 (from context, the date given as March 21 is considered +an error) at 5 p. m. following a heavy rain. The daily temperatures at +the time of Hamilton's observations "averaged 85° F., the first really +warm spell of the season." + +Eigenmann (1896:262) reported egg-laying of _spinifer_ in sand and +gravel in June and July at Turkey Lake (= Lake Wawasee), Indiana. A +turtle was seen digging a nest on June 26, and fresh nests of eggs +were found on June 27 and July 9. Hedrick and Holmes (1956:126) wrote +that a clutch of eggs of _spinifer_ in Minnesota was found about ten +inches deep in sand about one foot from the river; a steep gravel bank +was also cited as a favorite nesting site. Surface (1908:123) stated +that eggs of _spinifer_ in Pennsylvania are laid in May, and the young +hatch in August. Gehlbach and Collette (1959:142) found eggs of +_spinifer_ on June 19 on a sand bank 15 feet from the edge of the +Platte River in Nebraska. Breckenridge (1944:187) wrote that +_spinifer_ in Minnesota nests on sandy beaches from June 14 to July 6. +Cahn (1937:193) stated that deposition of eggs in Illinois occurs in +"June or early July: earlier in the southern part of the state, later +in the northern portion." Force (1930:38) mentioned a gravid female +from Oklahoma obtained on May 20. Evermann and Clark (1920:593) were +of the opinion that _spinifer_ began laying about mid-June and +continued until perhaps late July at Lake Maxinkuckee, Indiana; a +female opened on June 14 had oviducal eggs, and the first nest was +found on June 18. Nests were usually at the edge of an abrupt ascent +in sand; one nest was found in black, mucky soil (_op. cit._:595). +Newman (1906:128) wrote that _spinifer_ in the same lake nests later +than the other species of turtles, as a rule not earlier than the +middle of June (but as early as June 10, _op. cit._:132), and rarely +later than the middle of July; he observed deposition of eggs on June +22. Sites of deposition of eggs were mostly in soft sand not more than +six feet from water; other sites found by Newman (_op. cit._:132-33) +were a sandy, abandoned road bed separated from the shore by a strip +of tall grass, a rock pile (the eggs being dropped into crevices and +sand packed around them), among roots of a tree (the eggs being +deposited between the roots and under them in a very irregular +fashion), and in clay "so hard packed that one could scarcely break it +with the fingers." Natural nest sites in hard clay and a rock pile +seem incongruous with nesting habits of softshells. I note that +Newman's study was not begun until 1902 (_op. cit._:127), and it was +that year that the water level of the lake was high, flooding the +surrounding lowlands (Evermann and Clark, 1920:49-53). Perhaps some of +the nests found by Newman were old and not natural because of +conditions resulting from the receding water level. + +Newman (_op. cit._:134-35) mentioned that in small sandy areas nests +were frequently in contact and overlapped; he found one nest +containing nine small eggs contiguous with 23 large eggs. Breckenridge +(1944:187) reported a nest of 56 eggs of two slightly differing sizes, +and probably from two females. Evermann and Clark (1920:594) +discovered "probably 10 or 12 nests in a distance of a few yards" and +mentioned one nest containing 25 eggs "that evidently belonged to two +different sets ... In the bottom were 10 eggs that looked old ... and +... separated from them by sand, were 15 other eggs." + +Nesting sites of _muticus_ were mentioned by Muller (1921:181) on one +of several small islands having "gently sloping sand and mud shores, +and interior areas of open sand and densely growing willows" in the +Mississippi River, near Fairport, Iowa. The same author wrote that the +egg-laying season is from late June to early July, and that the female +selected a place 10 to 60 feet inland "with an unobstructed view of +the open water." Farther north on the Mississippi River near Dubuque, +Iowa, Goldsmith (1945:447) found that _muticus_ preferred "clean, +somewhat level sandbars and sandy shores free from trash, weeds ... +and exposed to open view." The same species, however, may "make +unsatisfactory nests ... in any place they can find sand, even in the +weeds and bushes ... when the river is high, covering the sandy plots +..." Sometimes nests, which were "seldom nearer than six feet or more +than twenty-five feet from water ...," were submerged by a rise in +water level. In Missouri, Hurter (1911:251) found that individuals of +_muticus_ came "... out on the sandbars in the Mississippi River to +deposit their eggs ... At the end of May up to the middle of June ..." +Cahn (1937:182) wrote that the nesting season of _muticus_ is early +July near Meredosia, Illinois. Anderson (1958:212, Fig. 1) found nests +of _muticus_ along the Pearl River in Louisiana on an open sandbar +(not in gravel, fine sand or silt), whereas nests of _Graptemys_ were +confined to the landward margin of the sandbar. + +The onset and length of the breeding season seems to be geared to the +climatic conditions under which the species occurs, and, as would be +expected, begins earlier and lasts longer in southern latitudes than +in northern latitudes. The period of deposition of eggs in _T. ferox_ +(Florida) is from late March to mid-July, whereas that of northern +populations of _spinifer_ and _muticus_ (southern Great Lakes region) +is usually from mid-June to mid-July. + +Seemingly there is little difference between species in preference of +nesting sites; a sandy substrate is probably preferred. Gravid females +of _ferox_ and _spinifer_ may wander overland some distance and select +places where the view of the water is obstructed by vegetation; both +species may wander little and nest in full view of the water. +Concerning _muticus_, it is of interest that of the many nests +discovered by Anderson (_loc. cit._) on an open sandbar, all were +those of _muticus_ and none was a nest of _spinifer_. The nests of +_muticus_ mentioned by Muller (_loc. cit._) and Goldsmith (_loc. +cit._) were on open sandbars. On June 4, 1953, six clutches of eggs +were found on an open sandbar of the Escambia River, Florida; all +hatchlings from those eggs that were successfully incubated were +_muticus_. On June 1, 1954, three nests were found on an open sandbar +of the same river (Pl. 50); the temperature within the nests at 6:30 +a. m. was approximately 25° C. Two nests were dug in a sand substrate +on the level portion of the bar (Pl. 51, Fig. 1). The third clutch of +eggs was deposited in a sand-gravel substrate at the brim of the +incline from the shore (approximately 30 degrees and about five feet +above the water); the eggs of this clutch were arranged rather +symmetrically (Pl. 51, Fig. 2). Unfortunately, most of the eggs from +these three clutches failed to hatch. Although the data are far from +conclusive, I have the impression that _muticus_ limits its sites of +egg deposition to the open regions of sand bars and does not lay +inland where it must traverse vegetated areas unless preferred nesting +sites are submerged or otherwise unsatisfactory. Females of _spinifer_ +may utilize open sandbars for deposition of eggs but not areas where +_muticus_ occurs. In areas where both _muticus_ and _spinifer_ occur, +the latter probably lays farther inland or on the landward margins of +sandbars. + +Excavation of nests has been observed in _ferox_ (Hamilton, 1947:209), +_muticus_ (Muller, 1921:181-82; Goldsmith, 1945:448), and _spinifer_ +(Newman, 1906:132-33; Cahn, 1937:191-92; Breckenridge, 1960:284). +Turtles leaving the water are cautious, usually stopping and extending +the neck to its greatest length, holding the head high, and sometimes +returning to the water for a short time. Depending on the condition of +the substrate and wariness of the female, nest construction may begin +immediately, or several holes may be dug and then abandoned. The +excavation on level ground or a slight incline is made by means of the +hind feet (Muller mentions digging with the forefeet; I agree with +Pope, 1949:321, and Conant, 1951:264, who consider Muller in error); +the forefeet are firmly planted and not moved during the excavation, +deposition of eggs or the filling of the nest cavity. The hind feet +are used alternately; cloacal water may be used to facilitate digging +or to provide a suitable substrate for the eggs. Cahn mentioned that +some sand may be flung four or five feet, and that during the digging +the head is held high. Breckenridge (_loc. cit._) reported that sand +was thrown a distance of ten feet. The nest may be completed in 16 +minutes (Cahn, _loc. cit._) or less than 40 minutes (Newman, _loc. +cit._). Breckenridge recorded 17 eggs laid in six minutes, Cahn +recorded 12 eggs laid in eight minutes, and Hamilton recorded four +eggs laid in three minutes. The hind feet are used to arrange the eggs +and are used alternately to fill the nest cavity; sometimes a little +sand is scraped in before all the eggs are deposited. Muller recorded +the nest cavity as five inches in diameter and ten inches deep, the +finished nest appearing "as a small crater ... about a foot in +diameter, or where the surface is covered with pebbles, as a circular +area of clear sand." Goldsmith reported that the nest cavity was six +to nine inches in depth, and that after deposition and filling with +sand "By certain twisting movements with all four legs, she drags the +plastron around over the sand, making a perfect camouflage." Newman +found the nest flask-shaped having a depth of about six inches, and +diameters of about three inches at the bottom and one and one-half +inches in the neck. Hamilton described a flask-shaped nest, the +entrance of which would "barely permit the passage of an egg ... the +bottom, at a depth of five inches, being about the width of a quart +milk bottle." Cahn related that the "hole descended at an angle of +about 60°," and the eggs thus rolled down an inclined plane. + +Possibly the nests of _ferox_ and _spinifer_ differ from those of +_muticus_ in being flask-shaped. A nest of _spinifer_ was reported by +Gehlbach and Collette (_loc. cit._) as having a neck three inches +across, a depth of six inches and a width of five inches at the +bottom. The nests of _muticus_ that I discovered on the Escambia River +were not flask-shaped; the eggs were five to seven inches below the +surface. Evermann and Clark (1920:594) reported eggs of _spinifer_ +"generally at a depth of four to ten inches," and Breckenridge (_loc. +cit._) found the topmost eggs about five inches below the surface. +There may be behavioral differences between _ferox_ and _spinifer_ and +_muticus_. Hamilton (_loc. cit._) mentioned that _ferox_ proceeded +with its reproductive duties even when he stood only a few yards away. +Muller (_op. cit._:181) found that _muticus_ would run to the water if +disturbed, without completing deposition of eggs; the same behavior +was described by Cahn (_op. cit._:191) for _spinifer_. Newman +(1906:133) wrote that _spinifer_ will abandon nesting activities if +surprised before egg deposition begins, but will wait to cover the +eggs if interrupted while laying eggs. Goldsmith (1945:448) found that +an observer did not disturb females of _muticus_ when they were laying +eggs (females "could be approached and even touched"), but that, in +the presence of an observer, they would scurry toward the water +without covering the eggs and would not return to cover them. Turtles +frightened in the process of the construction of the nests would not +return to complete the original nest. Harper (1926:415) wrote that +_ferox_, after completing nesting activities, will crawl a few feet +from the nest and scuffle up the surface, presumably to decoy +predators that might otherwise destroy the eggs; this observation has +not been corroborated by other authors. Harper (_op. cit._:416) +recorded the observation of Allen Chesser, who says that females, +after egg deposition, often "... bury themselves, before they go ter +the water, an' stay there ten er twelve hours." + + +_Reproductive Potential_ + +Estimates of reproductive potentials are subject to variation of one +kind or another. Counts of oviducal eggs or those in nests may be +misleading, as in some individuals one or more eggs may have been +deposited previously. Mitsukuri (1905:263), Newman (1906:135), Muller +(1921:182), and Cahn (1937:183) have mentioned that the number of eggs +per clutch corresponds to the size of the female. Females of northern +populations may have larger clutches than females of the same size +from southern populations. + + TABLE 8. Records in the Literature Pertaining to Number and Size + of Eggs of Three American Species of Trionyx. + + ===========+=====================+===================+======================= + | Number of eggs per | | + | clutch; oviducal | Size of eggs; | Authority + SPECIES | (o), nest (n); | ave. = average | and remarks + | ave. = average | | + -----------+---------------------+-------------------+----------------------- + _ferox_ | | 24 mm. | Agassiz (1857, pl. 7, + | | | fig. 20); nat. size. + | | | + | 22 (n) | ave. 31 mm. | Wright and Funkhouser + | | | (1915:120) + | | | + | some (o) | 32 mm. | " + | | | + | 20 (o) | ave. 25 mm., and | Goff and Goff + | | 12 gms. | (1935:156) + | | | + | 17 (o) | ave. 27 mm. | Hamilton (1947:209) + | | | + | 21 (o) | | " + | | | + | 7 (o) | | " (egg + | | | deposition probably + | | | interrupted) + -----------+---------------------+-------------------+----------------------- + _spinifer_ | | 29 mm., 26.5 mm. | Agassiz (1857, pl. 7, + | | | figs. 20 and 23, + | | | respectively); nat. + | | | size. + | | | + | 9, 12, 17, 18, 27 | | Eigenmann (1896:263); + | and 32 | | northern Indiana + | | | + | 9 to 24, ave. 18 | | Newman (1906:135); + | | | northern Indiana + | | | + | about 30 (n), 4 | 1.09 × 1 inch | Evermann and Clark + | (n), 3 (n) | | (1920:593-94); + | | | northern Indiana + | | | + | 21 (n and o) | (o) and some (n) | " + | | .93 × .93 inches; | + | | rest of (n) 1.07 | + | | × 1.07 inches | + | | | + | 32 (o) | ave. 1-1/4 inches | Force (1930:38); + | | | Oklahoma + | | | + | 9, 12, 13, 15, 17, | ave. 28.3 mm. | Cahn (1937:193); + | 19, 19, 21, 22, 23, | (217 eggs) | Illinois + | and 25; ave. 18 | | + | | | + | 12 (o), 26 (o), 24 | 22.0 to 28.5 mm. | Breckenridge + | (n), and 30 (n) | | (1944:187); Minnesota + | | | + | 21 (o) | 24 to 27.8 (ave. | Conant (1951:160); + | | 25.6 mm.) × | Michigan + | | 25.8 to 29 (ave. | + | | 27 mm.) | + | | | + | 22 (n), 22 or | | Hedrick and Holmes + | 23 (n) | | (1956:126); Minnesota + | | | + | 25 (n) | ave. 24 × 25.2 | Gehlbach and Collette + | | mm. | (1959:142); Nebraska + | | | + | 17 (n) | | Breckenridge + | | | (1960:284); Minnesota + -----------+---------------------+-------------------+----------------------- + _muticus_ | | about 22 mm. | Agassiz (1857, pl. 7, + | | | fig. 21); nat. size. + | | | + | 21 | about 20 mm. | Hurter (1911:249); + | | | Missouri + | | | + | 4, 12, 13, 16, 21, | ave. 2.3 cm. and | Muller (1921:182); + | 22, 26, and 33, all | 7 gms. | Iowa + | (n); ave. 22 | | + | | | + | 18 to 22, maximum | ave. 22.6 mm. | Cahn (1937:183); + | 31 | (116 eggs) | Illinois + | | | + | 93 from 5 nests, | variable--largest | Goldsmith (1945:449); + | ave. 18.6; 10, 10, | _ca._ 1-3/8 | Iowa + | 16, 17, 17, 19, 21, | inches, smallest | + | 21, 22, 22, 31, all | less than one | + | (n), ave. 18.7 | inch. | + -----------+---------------------+-------------------+----------------------- + +Additional records of size of clutch are provided by data from dissected +females (Table 9). All females were collected from May through September +from localities south of latitude 36.5°. The number of eggs includes +those in both oviducts, and the number of ovarian follicles those in +both ovaries. The number and range in size of only the largest group of +follicles is listed; in some instances the size of follicles formed a +graded series, and the designation of a group was arbitrary. + + TABLE 9. Length, Number of Oviducal Eggs, and Condition of Ovaries + in Adult Females of T. spinifer and T. muticus. + + ===========+========================+=========+====================== + | | | Ovarian follicles + | | | (total) + SPECIES | Size of female | Eggs +---------+------------ + | (plastral length, cm.) | (total) | | + | | | Number | Size (mm.) + -----------+------------------------+---------+---------+------------ + _muticus_ | 14.4 | 6 | 14 | 15-18 + | 16.3 | 9 | 4 | 15-17 + | 16.5 | | 3 | 16 + | 16.5 | 3 | 4 | 14-18 + | 17.2 | | 13 | 14-21 + | 27.0 | | 25 | 18-21 + -----------+------------------------+---------+---------+------------ + _spinifer_ | 16.2 | 7 | 4 | 16-20 + | 16.2 | 7 | 5 | 18-20 + | 16.2 | 7 | 1 | 18 + | 16.3 | 6 | 5 | 16-18 + | 16.3 | 4 | 5 | 15-19 + | 16.8 | 6 | 1 | 18 + | 17.3 | 3 | 2 | 17 + | 18.3 | | 13 | 19-20 + | 19.5 | | 2 | 17 + | 19.8 | | 4 | 20 + | 20.7 | | 11 | 15-18 + | 21.5 | | 6 | 8-11 + | 22.0 | | 13 | 11-14 + | 23.5 | 8 | 12 | 20-24 + | 25.5 | 11 | several | 18-22 + | 25.8 | 13 | ? | 18-21 + | 26.8 | 10 | 5 | 18-20 + | 30.5 | 13 | 5 | 20-21 + | | 16 | 16 | 16-21 + | | 11 | 19 | 15-20 + | | 17 | 23 | 18-22 + | | 17 | 22 | 14-20 + | | 8 | 15 | 18-22 + -----------+------------------------+---------+---------+------------ + +Published data (Table 8) indicate that the average number of eggs per +clutch for the three American species is about 20, although the number +of eggs may exceed 30 in _spinifer_ and _muticus_. Except for those of +_ferox_, most of these records are based on observations in northern +latitudes (approximately 40°). My examination of females from southern +latitudes (below 36.5°) reveals no oviducal egg count greater than 17 +and an average number of eggs per clutch of 9.6 per _spinifer_ (Table +9); that of _muticus_ is 7.3, as based on data given in Table 9 as +well as on egg-nest counts of 15, 6, 6, 6, 6, 5, 9, 8, and 8. Ovarian +follicles larger than 15 millimeters in diameter are arbitrarily +considered to comprise the next clutch that will be deposited in the +current season. Follicles of this size possibly are retained until the +following year or some may undergo regression; some of the included +follicles may not be representative of the succeeding egg complement. +The average number of follicles of the most enlarged groups is 9.0 for +_spinifer_ and 10.5 for _muticus_. Females in northern latitudes +probably have a greater reproductive potential than those in southern +latitudes if it is assumed that there is only one laying per season +for an individual; the maximum number of eggs laid at any one time +probably does not exceed 35. There is also an indication that larger +females deposit more eggs than smaller females (Table 9). Muller +(1921:184) mentioned two double eggs (each having two yolks) in the +complement of 33, indicating an abnormally large number and excessive +crowding of eggs in the oviducts. Simkins (1925:188) also mentioned +some eggs of a clutch (form and locality unknown) that were five or +six millimeters larger (about 31-32 mm.) than the rest, and which +"invariably bore twins." The largest number of eggs in a single nest +mentioned by Simkins is 22. If the presence of double-yolked eggs is +indicative of crowding of eggs in the oviducts, the egg complements of +22 and 33 indicate the approximate maximal number of eggs per clutch. +In the species _spinifer_, the average size of sexually mature females +is slightly smaller at some places in the south than in the north. +Therefore, smaller clutches are to be expected in the south. + +Many of the females collected in June or July contained corpora lutea +four to eight millimeters in diameter in addition to enlarged ovarian +follicles. Presumably the corpora lutea indicate clutches deposited +earlier in the current season, and the enlarged follicles represent +clutches to be deposited in the current season. One female of +_muticus_ (OU 27593) obtained on July 10, contains oviducal eggs, +ovarian follicles 15-17 millimeters in diameter, and corpora lutea of +different sizes that exceed the number of oviducal eggs; possibly this +female was capable of laying three clutches each season. Corpora +lutea, representing ovulation points of eggs in the oviducts, are +approximately eight millimeters in diameter. In order to establish +definitely the reproductive potentials of any species of turtle, it is +desirable to know the approximate size of ovarian follicles that are +retained by sexually inactive females, and the rate of regression of +the corpora lutea. The data suggest that, in southern populations at +least, two and possibly three clutches of eggs are deposited in the +annual breeding season. Mitsukuri (_in_ Cagle, 1950:38) found that _T. +sinensis_ deposited four groups of eggs each season. + +It is suggested that the seasonal reproductive potential of northern +populations (averaging about 20 eggs per clutch, and probably one +clutch per season) is less than that for southern populations +(averaging about 10 eggs per clutch, but three clutches per season). +But owing to variation, there may be no great discrepancy between the +actual potentials of northern and southern populations. + + +_Eggs_ + +The eggs of _Trionyx_ are white and spherical having a brittle shell. +Some eggs are occasionally abnormal in shape and size; overcrowding of +eggs in the oviducts may result in small, irregular-shaped eggs, or +large double-yolked eggs. Presumably enlargement of the eggs occurs in +the oviducts and within a short period after deposition prior to +complete hardening of the brittle shell; therefore some eggs in the +oviducts are smaller than those in nests. + +The data concerning _ferox_ (Table 8) suggest that the maximum size of +eggs is 31 to 32 millimeters, whereas oviducal eggs are slightly +smaller, about 25 to 27 millimeters. Eggs of _spinifer_ from northern +latitudes (most from approximately 40°, Table 8) also vary in size, +oviducal eggs being as small as 22 millimeters in diameter and the +maximal size about 29 millimeters. Average extreme measurements (in +mm.) of oviducal eggs (number of eggs in parentheses) from females +taken in latitudes of 33 degrees or less are: 25 × 29 (11), 29 × 30 +(11), 28 × 30 (13), 28 × 30 (10), 29 × 30 (5), 29 × 29 (8), 25 × 26 +(17), 29 × 30 (5), and 28 × 29 (8). The average size of these eggs is +slightly larger than the oviducal eggs of which measurements are given +in Table 8, and suggest larger eggs from more southern latitudes. Eggs +of _muticus_ are smaller than those of _spinifer_ (Cahn, 1937:183) or +_ferox_; the average size of eggs from nests found in Iowa and +Illinois is 22 to 23 millimeters (Table 8). Nine oviducal eggs from a +female obtained in Lake Texoma, Oklahoma, averaged 22 × 23 +millimeters. The largest eggs of _muticus_ are from the southernmost +locality; eight eggs from a nest found along the Escambia River, +Florida, averaged 26 × 27 millimeters. + +In general, the data suggest that at each laying slightly smaller eggs +but larger numbers are laid by females in northern latitudes, whereas +larger but fewer eggs are laid by females from farther south. + + +_Incubation and Hatching_ + +Length of the incubation period seems to depend upon conditions of +heat and moisture, and, in general, to be geared to the prevailing +climatic conditions. Goff and Goff (1935:156) artificially incubated +some eggs of _ferox_ at temperatures varying from 82.3 to 89.2° F., +and found that the incubation period was 64 days. Muller (1921:184) +wrote that the period of incubation of eggs of _muticus_ (natural +nests at temperatures about 90°., _op. cit._:182, and artificial +nests) in Iowa is from 70 to 75 days. Breckenridge (1944:187) stated +that _spinifer_ makes nests in Minnesota from June 14 to July 6, and +cited reports that indicate hatching in September. Hedrick and Holmes +(1956:126) discovered a nest of eggs in Minnesota on September 5; the +eggs were artificially incubated and some hatched on October 29. +Eigenmann (1896:263) found eggs as late as September in northern +Indiana that "contained young which would have been ready to hatch +about a month later." Cahn (1937:193) wrote that _spinifer_ in +Illinois lays in June or early July and that "young-of-the-year are +taken in late August and September." Some recently deposited eggs of +_muticus_ (as indicated by fresh turtle tracks, Pl. 50, Fig. 2) that I +obtained on June 1 were artificially incubated and hatched on August +4, indicating an approximate incubation period of 65 days. Dr. Paul K. +Anderson in the course of field work on the Pearl River, Louisiana +(1958:211), found that eggs collected on June 13 from a nest excavated +three to five days before, hatched on August 15, indicating an +incubation period of approximately 67 days. Eggs collected on May 17 +to 25 (three clutches) hatched on August 4 to 6, indicating an +incubation period of approximately 77 days. In any latitude the +incubation period probably is at least 60 days. Eigenmann (_loc. +cit._), however, mentioned empty nests that were found in July; this +indicates early hatching or more probably the action of predators. + +In northern latitudes eggs or young turtles may over-winter in the +nest if deposition is late in the season. In northern Indiana Evermann +and Clark (1920:595) found a nest on November 16 that contained +"well-formed young" and believed that the turtles would have wintered +in the nest. Conant (1951:160) was of the opinion that most eggs +probably hatch in early fall, but that some do not hatch until spring. + +The hatching of eggs of _muticus_ has been described by Muller +(1921:183). According to him, the forelimbs first emerge through the +shell and enlarge the opening. There is an "egg tooth below the +flexible proboscis" but "it does not seem to be used in escape from +the eggs, and is dropped a week after hatching." Hatchlings burrow +almost straight upward through the sand leaving the egg shell below +the surface and a hole in the sand about an inch in diameter. Muller +found that young turtles emerge from the nests in the night or early +morning and always go downhill probably influenced in their movements +by the open sky and sloping beach. Anderson (1958:212-15) found that +hatchlings of _muticus_ leave nests within the first three hours after +sunset and travel a direct route to the water. He discovered that +hatchlings are active on the surface of the sand at night and +generally show a positive reaction to light (moonlight, flashlight), +whereas, in daytime, there is a negative reaction to bright sunlight +(causing the turtles to bury themselves in sand). Anderson believed +that the positive response to light at night is not correlated with +the water-approach behavior of hatchlings, but that movements to water +are possibly influenced by a negative reaction to dark masses of +environment (such as shadows formed by landward forests). + + +_Age and Growth_ + +Goff and Goff (1935:156) found that hatchlings of _ferox_ average 8.82 +grams (extremes, 8.50 to 9.25); one of these, UMMZ 76755, is +illustrated in Plate 31. Muller (1921:184) recorded measurements of +five hatchlings of _muticus_; the average measurements (in cm., +extremes in parentheses) were: length of carapace, 3.54 (3.43 to +3.67); width of carapace, 3.20 (3.10 to 3.25); length of plastron, +2.54 (2.47 to 2.60). I recorded measurements of 32 hatchlings (three +clutches combined) of _muticus_ on August 16; the turtles hatched on +August 4 to 6 from eggs collected along the Pearl River, Louisiana. +The average measurements (in mm., extremes in parentheses) of the 32 +turtles were: length of carapace, 41.3 (34.0 to 45.0); width of +carapace, 38.6 (31.0 to 40.0); length of plastron, 30.1 (25.0 to +32.0). These turtles have circular umbilical scars averaging +approximately two millimeters in diameter. The smallest hatchling that +I have seen measures 21.0 millimeters in plastral length (_T. m. +muticus_, INHS 3458). There are no data to indicate a difference in +size of hatchlings among the American species of soft-shelled turtles. +The average plastral length of most hatchlings probably is 28.0 to +30.0 millimeters. + +Owing to the lack of a horny epidermal covering of the carapace and +plastron, soft-shelled turtles are not so well suited to studies of +age and growth as are the "hard-shelled" species, which have visible +impressions of growth annuli on the epidermal scutes. Mattox +(1936:255) found annular rings in the long bones of specimens of +_Chrysemys_ and suggested that it is tenable to correlate the number +of rings with the age of the turtle. + +Mitsukuri (1905:265) reported that in hatchlings of _Trionyx sinensis_ +the length of the carapace averages 2.7 centimeters (hatchlings of +_sinensis_ seem to average smaller than any American species), and +that the average length of carapace (cm.) at the end of the first year +is 4.5, second year 10.5, third year 12.5, fourth year 16.0, and end +of fifth year 17.5; he stated also that females of _sinensis_ are +sexually mature in their sixth year. Breckenridge (1955:7-9) computed +a growth curve based on 11 recaptures of females of _spinifer_ in +Minnesota; his data on rate of growth for the first five years do not +differ appreciably from those of Mitsukuri. As most females of +_spinifer_ are sexually mature when the carapace is about 11 inches +long, the age at sexual maturity is approximately 12 years according +to Breckenridge (_op. cit._:8, Fig. 4). The discrepancy in age of +females at the size of attainment of sexual maturity (Mitsukuri--six +years; Breckenridge--12 years) is, in part, rectified by the fact that +_Trionyx sinensis_ probably is a smaller species. Also, Breckenridge's +computation of the growth curve is based on continuously decreasing +increments of growth and seemingly eliminates consideration of the +probable marked decrease in rate of growth that occurs when sexual +maturity is attained--a phenomenon noted in other species of turtles. +I think that increments of growth of immature turtles are, on the +average, larger than those of sexually mature turtles. Judging from +these criteria, the age of a female of _spinifer_ at sexual maturity +is less than 12 years, and turtles having carapaces 17 to 18 inches in +length (maximal size for _spinifer_) would be older than 53 years +(_op. cit._:9). Occasional individuals, however, may greatly exceed +the usual growth rate in which event large adults may be younger than +50 years. + +Females of _muticus_ are sexually mature when the plastron is 14.0 to +16.0 centimeters long, which corresponds to a carapace 19.6 to 22.4 +centimeters (about 7-3/4 to 8-3/4 inches) long (average CL/PL +approximately 1.4, see Fig. 13). The smaller adult females probably +mature sexually in their sixth year, but most probably do so when +seven years old. Accordingly, some _T. spinifer emoryi_, which are +sexually mature at a plastral length of 16.0 centimeters, are also +sexually mature in their seventh year, whereas most _spinifer_ +(sexually mature at a plastral length of 18.0 to 20.0 cm., +corresponding to a length of carapace of 25.2 to 28.0 cm. or about 10 +to 11 inches) probably become sexually mature in their ninth year, and +some when eight years old. Most males of _spinifer_ are sexually +mature when the plastron is 9.0 to 10.0 centimeters long (length of +carapace 12.6 to 14.0 cm. or 5 to 5-1/2 inches), whereas males of +_muticus_ and some _T. spinifer emoryi_ are sexually mature at a +plastral length of 8.0 to 9.0 centimeters (length of carapace 11.2 to +12.6 cm. or 4-1/2 to 5 inches). The smaller adult males are probably +sexually mature in their fourth growing season. Breckenridge (_op. +cit._:7, Tab. II) commented on the abundance of females between five +and 12 inches in length, and males that ranged in length from five to +seven inches. The abundance of turtles in these size ranges is +probably due, in part, to a slowing of the rate of growth indicating +the approach of sexual maturity; the abundance of the smallest males +is especially in accord with the size at sexual maturity of males +(about five inches). + +The largest acceptable record of size of _spinifer_ is 18 inches in +length of carapace (Breckenridge, 1957:232). Stockwell (1878:402), +however, wrote that females of _spinifer_ attain "an extreme length of +from twenty-four to twenty-eight, and, in rare instances, thirty +inches, with an average length of carapace of fifteen to eighteen," +and True (1893:152) mentioned lengths of two feet or even more. +Turtles 17 to 18 inches long are doubtless rare and probably about 60 +years old. A specimen of _ferox_ lived the longest time in +captivity--25 years (Pope, 1949:304). Individuals of _ferox_ probably +exceed the maximum recorded length of carapace of 18-1/2 inches +(Agassiz, 1857:401). The head of a _ferox_ having a width of 3-1/2 +inches (Wright and Funkhouser, 1915:120) corresponds to a length of +carapace of approximately 22-1/2 inches (PL/HW == 4.9; CL/PL == 1.3). +De Sola and Abrams (1933:12) wrote that _ferox_ in the Okefinokee +Swamp, Georgia, attains a length of two feet. The largest female of +_muticus_ of which I have record is 21.5 centimeters in plastral +length (KU 2308), a measurement corresponding to a carapace about 13 +inches long. + + +Mortality + +Man, in one sense or another, is a great enemy of soft-shelled +turtles. Those caught by fishermen are destroyed because of the +erroneous belief that they are harmful to fish populations. Some are +drowned in hoop-nets or gill nets used by commercial fishermen. Many +softshells are used by man for food. Herald (1949:118-19) reported the +results of spraying an area with DDT and mentioned a 10-inch +individual of _ferox_ that was eating a dead bluegill, and which +"probably died as a result of ingesting contaminated food." + +Predation on eggs probably accounts for most mortality. Hamilton +(1947:209) reported tracks of spotted skunks, raccoons and foxes seen +about destroyed nests, and Cahn (1937:183) incriminated skunks and +raccoons. Goldsmith (1945:449) reported a raccoon that unearthed seven +nests in one night. Little and Keller (1937:221) wrote of egg shells +found in the sand (probably not as a result of hatching), and Muller +(1921:182) reported egg shells around dug-up nests, suggesting such +predators as "ground moles," raccoons and crows. Chesser (_in_ Harper, +1926:416) said that in the Okefinokee Swamp the jackdaw (fish crow), +raccoon, bear and domestic dogs will eat the eggs. Wright and +Funkhouser (1915:122) recorded a young _ferox_ in the stomach of a +water moccasin (_Agkistrodon piscivorus_), and suggested that young +soft-shells probably are food of larger snakes. Kellogg (1929:26) +wrote that stomachs of two alligators each contained one soft-shelled +turtle. Newman (1906:136) found that young captives were eaten by +individuals of _Chrysemys_ and _Sternothaerus_, and I found that they +were eaten by _Kinosternon_. Mitsukuri (1905:261-62) stated that +first- and second-year individuals of _T. sinensis_ are eaten by the +adults. + +Breckenridge (1960) wrote that a clutch of eggs probably failed to +develop because of an "... unusually cool season." Evermann and Clark +(1920:595) stated that "many young appear to perish during the first +winter." They (_op. cit._:594) found two eggs submerged in two feet of +water and it is supposed that they never hatched. Dundee (1950:139) +reported remains of soft-shelled turtles left on the mud of a dried +swamp. + + +Parasites + +Muller (1921:182) found maggots in a few eggs of a clutch, but thought +that only the infertile and decomposing eggs were infested. I removed +a hard, spherical cyst from the hind leg of a preserved softshell +(TU). A captive hatchling (TU 17304) died as the result of a +continuously enlarging and deepening hole on the top of its head; I +could not discern a visible parasite with the naked eye. I found 25 +leeches (_Placobdella parasitica_, largest about 13 mm.; identified by +Dr. Kenneth B. Armitage, Department of Zoology, University of Kansas) +in association with 11 _T. m. muticus_ (number per turtle not known) +that were collected from the Kansas River at Lawrence, Douglas County, +Kansas. Evermann and Clark (1920:596) reported a few nematodes in the +stomachs of some _spinifer_, and three nematodes are listed by Harwood +(1932:46, 60, 62, 66) in the same species. Hughes, Higginbotham and +Clary (1941) have listed the known reptilian hosts of parasitic +trematodes, and Hughes, Baker and Dawson (1941) have done the same for +tapeworms. The species of parasites and their trionychid hosts are +listed below. + + TREMATODA + _Trionyx ferox_: _Neopolystoma orbiculare_ _Vasotrema amydae_ + _Neopolystoma rugosa_ _Vasotrema attenuatum_ + _Polystomoides coronatus_ _Vasotrema robustum_ + _Teloporia aspidonectes_ + + _Trionyx muticus_: _Crepidostomum cooperi_ _Opisthorchis ovalis_ + + _Trionyx spinifer_: _Hapalorhynchus evaginatus_ _Vasotrema amydae_ + _Opisthorchis ovalis_ _Vasotrema attenuatum_ + _Polystomoides coronatus_ _Vasotrema longitestis_ + _Teloporia aspidonectes_ _Vasotrema robustum_ + + CESTODA + _Trionyx ferox_: _Proteocephalus trionychinus_ + + _Trionyx spinifer_: _Proteocephalus testudo_ + + NEMATODA + _Trionyx spinifer_: _Camallanus trispinosus_ _Spiroxys amydae_ + _Falcaustra chelydrae_ + + +Economic Importance + +Several authors have mentioned softshells as a food item much sought +after by man. The commercial value of these turtles has been +summarized by Clark and Southall (1920:15-16). Softshells are consumed +in quantity only in small towns near the place of capture. They are +found only occasionally in the markets of large cities because the +turtles are little known and the palatability of their flesh is +unappreciated. Also, they do not stand shipment so well as other +turtles, and they are "not so meaty as the snapper; so there is more +waste" (Clark and Southall, _loc. cit._). Little and Keller (1937:221) +reported living individuals for sale at the market in Ciudad Juarez, +Chihuahua; however my inquiry at markets in Juarez in the summer of +1959 disclosed no evidence of recent sale of soft-shelled turtles. In +the southeastern United States the demand is perhaps greater than in +other regions. I have noted softshells in the market at New Orleans, +and Oliver (1955:19) has mentioned the sale of "some 146,600 pounds" +in one recent year in Florida. Over most of their range, however, +there probably is no general demand for softshells and no special +efforts are made to capture them. Softshells have been raised +successfully on "turtle farms" in Japan (Mitsukuri, 1905). True +(1893:152) wrote that "The eggs also are considered very excellent." + +Softshells generally are condemned by fishermen because of the +mistaken belief that they are detrimental to fish populations. Food of +softshells is principally crawfish and insects. Fish comprise a small +proportion of the diet (frequency 1.9% in Michigan, Lagler, 1943: Tab. +9). Most of the fishes eaten seem to be small minnows. Probably fish +would comprise a larger percentage of the diet if they could be +caught. I doubt that a softshell can pursue and capture a healthy fish +in natural waters. Recently dead fish are eaten and perhaps fish eggs, +and senile and decrepit fishes. There is no evidence that soft-shelled +turtles are active predators on any kind of fish. Of course in +congested areas such as ponds of fish hatcheries, it is desirable to +eliminate the turtles. The known food habits of soft-shelled turtles +suggest that they compete with game fishes for food, but there is no +information on the intensity of competition (Lagler, _op. cit._:305). + +The combined statements of many authors in their general accounts of +food habits (for instance, Babcock, 1919:425) have tended to create +the erroneous belief that soft-shelled turtles harm waterfowl. To my +knowledge the only basis for this belief is the statement of Wright +and Funkhouser (1915:123) that according to the natives of the +Okefinokee Swamp, the larger turtles "devour also such waterfowl as +are unfortunate enough to be taken unaware by these reptiles." Perhaps +an occasional waterfowl is eaten, but the present information on kinds +of food eaten certainly does not warrant the destruction of +soft-shelled turtles. There may be some mortality in congested areas +such as game refuges where young birds crowd the surface of the water. + +The kind of bait successfully used in trapping softshell turtles +suggests that they are of some value as scavengers. + + + + +EVOLUTIONARY HISTORY + + +Before attempting to reconstruct the history of soft-shelled turtles +in North America, it will be helpful to summarize the salient facts +concerning the distribution and relationships of the living forms, and +to comment on fossils. + + +Distribution + +The geographic range of the family Trionychidae in North America is +principally in the eastern two-thirds of the continent and contributes +to the well-known floral and faunal resemblance of eastern North +America to that of eastern Asia (Schmidt, 1946:149) because _Trionyx +ferox_ (see Fig. 18) resembles the species of the genus in Asia more +closely than it does any North American species. The Recent +distribution in America does not include the Neotropical region, +whereas the geographical range in the Old World extends south of the +equator (Fig. 1; Dunn, 1931:109, fig. 2; Gadow, 1909:333, fig. 72; +Hay, 1908:35, fig. 16). + +American softshells occur in all river systems in the United States +and the two adjacent river systems on the east coast of México that +drain into the Gulf of México. Softshells inhabit streams of the Great +Plains and occur westward to the foothills of the Rocky Mountains in +the western tributaries of the Mississippi River. Only _T. s. +spinifer_ occurs in the southern part of the Great Lakes-St. Lawrence +drainage. Softshells are absent from the Atlantic Coast drainage +except the Hudson River and those rivers at least south of (and +including) the Pee Dee River in South Carolina. + +_T. s. emoryi_ is not known to be indigenous west of the Río Grande +drainage, and has probably been introduced across the Continental +Divide via the Gila River in western New Mexico into the Colorado +River drainage of Arizona (Miller, 1946:46); the species undoubtedly +occurs in México on the Sonoran side of the Colorado River opposite +Baja California (Bogert and Oliver, 1945:417). + +In the summer of 1959, I trapped turtles and with a specimen in hand +inquired about softshells occurring in the inland drainages of +northern México. From two collecting stations on the Río Nazas in +Durango, only specimens of _Pseudemys_ and _Kinosternon_ were +obtained; local inhabitants had neither seen nor heard of softshells. +Flooded conditions in August of 1959 permitted trapping in only one of +the inland drainages of northwestern Chihuahua, the Río Santa María; +only specimens of _Kinosternon_ were obtained. Local residents near +that river as well as those living near the Río Casa Grandes and Río +del Carmen had not seen or heard of softshells. A person that I judge +to be a competent observer reported seeing a softshell in June of 1958 +in the Río Alamos (Arroyo Cuchujáqui) near Alamos, Sonora, in the Río +del Fuerte drainage on the west coast of México. I was a member of a +field party from the University of Kansas that visited that locality +in late January of 1959; only specimens of _Pseudemys_ and +_Kinosternon_ were collected. Possibly isolated populations occur in +streams of the Pacific Coast drainage of northern México. If so, they +may have entered Pacific Coast drainages by stream capture across the +Continental Divide. Several species of fish that are characteristic of +the Río Grande traversed the Sierra Madre Occidental at some former +time (presumably via the Río Conchos and Río Papigochic) and occur in +the Yáqui River drainage (Meek, 1904:xxxviii, xlvii; Miller, +1959:214-15, 217). Because of the probability that the Río Nazas at +some former time flowed north into the Río Grande (Meek, _op. +cit._:xxxiv), it is notable that softshells are absent in the Río +Nazas drainage; the Big Bend turtle, _Pseudemys scripta gaigeae_, +occurs in both drainages. + + +Relationships + +Characters of _Trionyx ferox_ suggesting a closer resemblance to some +Old World members of the family than to the other three American species +are: large size; marked difference between juvenal and adult patterns on +the carapace; the marginal ridge; and the longitudinal ridgelike +prominences on the carapace, especially in juveniles. Other characters +of _ferox_ suggesting a corresponding, but less marked resemblance to +Old World species of _Trionyx_ are: the large size of the eighth pair of +pleurals; the absence of callosities on the epiplastron and preplastra; +frequent fusion of the hyoplastra and hypoplastra (more than in +_spinifer_ or _muticus_); and tolerance of marine waters (more than +_muticus_ or _spinifer_). Some fossils also suggest alliance with +_ferox_ and some Old World members of the genus in their large size, +large eighth pair of pleurals, and occurrence in marine deposits; +several Old World species have been reported at sea (_Pelochelys_, _T. +triunguis_, _T. sinensis_). _T. ferox_ is monotypic and has the most +southeasterly displaced, geographic range. + +Because _ferox_ resembles softshells from the Old World more closely +than it does any American species, _ferox_ is assumed to be more closely +related to Old World softshells than to any American species, and, +because of resemblance to some fossils, _ferox_ is assumed to resemble +most closely the primitive, ancestral stock of softshells that occupied +North America. _T. spinifer_, _T. muticus_ and _T. ater_, which resemble +each other more closely than any of them resembles _T. ferox_ or any Old +World species, are considered autochthonous in North America. _T. +spinifer_ and _T. muticus_ are distinct, sympatric species. Burt +(1935:321) suggested that the two species "may be variants of the same +species." _T. ater_ is weakly differentiated from _T. spinifer emoryi_. +The species, _ferox_, _spinifer_ and _muticus_ are well-differentiated +and were considered by Agassiz (1857), Gray (1869) and Baur (1893) as +belonging to three different genera. + +In the widely distributed _T. spinifer_, the subspecies _spinifer_, +_hartwegi_ and _asper_ closely resemble one another; _asper_ seems most +distinct, whereas _spinifer_ and _hartwegi_ are terminal populations of +an east-west cline in one character. The subspecies _pallidus_, +_guadalupensis_ and _emoryi_ resemble one another more closely than any +resembles any of the subspecies mentioned immediately above; _T. s. +pallidus_, however, is annectent. _T. s. pallidus_ and _guadalupensis_ +represent terminal populations of clines in several characters, some of +which occur in _emoryi_, but that subspecies is more distinct from +_pallidus_ and _guadalupensis_ than those subspecies are from each +other. _T. s. emoryi_ is the most variable subspecies. _T. ater_, known +only from a restricted area in central Coahuila, is most closely related +to _T. s. emoryi_, and possesses some characters judged to represent the +attenuation of the geographic cline in _pallidus_, _guadalupensis_ and +_emoryi_ mentioned above. Some characters of _ater_ show alliance to the +species _muticus_. Of _T. muticus_, whose geographic range is removed +from that of _ater_, there are two subspecies. Four subspecies of +_spinifer_ (_spinifer_, _hartwegi_, _pallidus_ and _asper_) intergrade +in the Mississippi River drainage of Louisiana; few specimens, however, +are typical of _asper_. The subspecies of _muticus_ do not show definite +evidence of intergradation. To facilitate quick reference, the +occurrence of some characters that are shared by, or are approximated +in, two or more forms are listed in Table 10. In addition to external +characters, some ratios emphasize the clinal relationship between _T. s. +pallidus_, _guadalupensis_, and _emoryi_ mentioned above. Of especial +interest is the frequent resemblance of those subspecies and _T. ater_ +to _T. ferox_ (dorsal pattern on limbs of adults, reduction in anterior +tuberculation, wide head, narrow carapace, and short snout), and the +less marked resemblance of _T. muticus_ to _T. ferox_; not shown in +Table 10 is the resemblance of _ferox_ to _T. muticus calvatus_ in +having thick, black-bordered postocular stripes. Some populations of _T. +s. emoryi_ resemble _T. muticus_ in the corresponding size at sexual +maturity and in having well-developed plastral callosities. It is +notable that the occurrence of _ater_, and to a lesser extent that of +_T. s. emoryi_, which resembles _ferox_ (and _muticus_), is in the +southwestern United States and northern México. + + TABLE 10. Frequency of Selected Characters Among Species and + Subspecies of Trionyx in North America. Characters of muticus + Refer to the Typical Subspecies; Horizontal Dashes Connecting + X's Indicate that Computations for Those Subspecies Were + Combined; Vertical Dashes Indicate that the Subspecies Is + Intermediate Between the Adjacent Subspecies. + + Column headings: + + A: _ferox_ + B: _spinifer_ + C: _hartwegi_ + D: _asper_ + E: _pallidus_ + F: _guadalupensis_ + G: _emoryi_ + H: _ater_ + I: _muticus_ + + =====================================+=================================== + | Species and subspecies + Characters +---+---+---+---+---+---+---+---+--- + | A | B | C | D | E | F | G | H | I + -------------------------------------+---+---+---+---+---+---+---+---+--- + Juvenal pattern: | | | | | | | | | + black spots, ocelli | | X | X | X | | | | | + | | | | | | | | | + white dots | | | | | X | X | X | X | + -------------------------------------+---+---+---+---+---+---+---+---+--- + Pattern on snout: | | | | | | | | | + acute angle (reduced in _muticus_) | X | X | X | X | X | | | | X + | | | | | ¦ | | | | + triangular | | | | | X | X | X | X | + -------------------------------------+---+---+---+---+---+---+---+---+--- + Pattern on side of head: | | | | | | | | | + contrasting marks | X | X | X | X | X | X | | | + | | | | | | ¦ | | | + non-contrasting marks (distinct | | | | | | ¦ | | | + stripe in _muticus_) | | | | | | X | X | X | X + -------------------------------------+---+---+---+---+---+---+---+---+--- + Pattern on limbs of adults: | | | | | | | | | + contrasting | | X | X | X | X | X | | | + | | | | | | ¦ | | | + reduced or absent | X | | | | | X | X | X | X + -------------------------------------+---+---+---+---+---+---+---+---+--- + Tuberculation (anterior edge of | | | | | | | | | + carapace): | | | | | | | | | + conical, equilateral | | X | X | X | X | | | | + | | | | | | | | | + reduced or absent | X | | | | | X | X | X | X + -------------------------------------+---+---+---+---+---+---+---+---+--- + Head (PL/HW, fig. 3): | | | | | | | | | + wide | X | | | X | | X | X | X | + | | | | | | | | | + narrow | | X | X | | X | | | | X + -------------------------------------+---+---+---+---+---+---+---+---+--- + Carapace (CL/CW, fig. 4): | | | | | | | | | + wide | | X | X | X | X | X | | | X + | | | | | | ¦ | | | + narrow | X | | | | | X | X | X | + -------------------------------------+---+---+---+---+---+---+---+---+--- + Level of Carapace Width (CL/PCW, | | | | | | | | | + fig. 5): | | | | | | | | | + middle of carapace | X | X | X | X | | | | | X + | | | | | | | | | + farther posteriorly | | | | | X | X | X | X | + -------------------------------------+---+---+---+---+---+---+---+---+--- + Snout (HW/SL, fig. 6): | | | | | | | | | + long | | X---X | X | X---X | | | X + | | | | | ¦ ¦ | | | + short | X | | | | X---X | X | X | + -------------------------------------+---+---+---+---+---+---+---+---+--- + + +Fossils + +The known occurrence of fossil trionychids throughout the world +indicates a former distribution more widespread than the family has +today; the principal difference in the former and present distributions +is the lack of living softshells in Europe. + +I have not studied in detail the many fossil remains but such +examination as I have made of them suggests that many of the characters +used as a basis for distinguishing fossil forms in North America are +subject to individual variation or are of no diagnostic value in the +living species (Hummel, 1929:769). Knowledge of the variation in the +living species of the Old World would aid in adequately appraising the +North American fossils. Some osteological characters of the three living +American species (excluding _ater_) together with data on variation +within a given species are mentioned below. Some differences in skulls +of the three species already were mentioned in the section "Osteological +Characters." Because most fossil remains are those of the carapace and +plastron, attention is here given to those structures. + +_Widened alveolar surfaces of jaws._--An ontogenetic variation +affecting large skulls of _T. ferox_ and some individuals of _T. +spinifer asper_; presumably confined to females. Of especial interest +is its presence in some populations of _asper_ that are not otherwise +distinguishable (external characters) from the rest of the individuals +comprising that subspecies. + +_Sculpturing._--No differences in pattern (generally of anastomosing +ridges) on carapace or plastron; fineness or coarseness seemingly +correlated with size; frequency and kind (knoblike or ridgelike) of +bony prominences on carapace variable; bony prominences confined to +species _spinifer_ and _ferox_, occurring principally on large +females. + +_Fontanelles of carapace._--Closure more or less correlated with +increasing size, although much variation noted between individuals of +same size; small individuals have fontanelles confluent (medially), +thus separating nuchal from contact with first neural and first pair +of pleurals. + +_Number and arrangement of neurals and pleurals._--Neurals number six +to nine, usually seven or eight; pleurals number seven or eight pairs, +and may or may not be in contact with each other posteriorly; eighth +pair of pleurals when present reduced, never contacting seventh +neural; arrangement posteriorly variable (see Fig. 16 and Tab. 5). + +_Plastral callosities._--Increase in size with advancing age causing +corresponding reduction in size of plastral vacuity; relatively best +developed in _muticus_ (all elements touching medially on KU 41380 +leaving no plastral vacuity); probably no callosities on preplastra or +epiplastron of _ferox_; callosity on epiplastron of _spinifer_ not +covering entire surface (as it may in _muticus_). + +_Epiplastron._--Obtusely-angled (greater than 90 degrees) in +_muticus_; acutely-angled (90 degrees or less) in _ferox_ and +_spinifer_. + +_Hyo-hypoplastral suture._--Usually present, but occasionally absent, +in all species. + +The fossil turtles of North America have been treated monographically by +Hay (1908), who apportioned fossil trionychid remains into eight genera +(three living) of two families. Recently, Romer (1956:514) relegated all +trionychid fossils to the genus _Trionyx_. Characters, as gleaned from +Hay's synopsis (_op. cit._:465-548, Pls. 85-113), that seem especially +worthy of taxonomic consideration are: (1) The presence of a preneural, +which is not known to occur in the living American species (seemingly +the preneural is fused with the first neural and represents the elongate +first neural in living species); (2) The large eighth pair of pleurals, +especially when they contact the seventh neural; (3) The thickness of +the costal plates, a condition probably correlated with the size of some +fossils, which are larger than any living species (for example, Hay, +_op. cit._:518, mentioned the greatest dimension of a nuchal bone as +approximately 300 mm.). + +The approximate extent of the known horizontal distribution of fossils +is indicated in Figure 24. A comparison of known localities of fossils +and the distribution of living softshells (introduced population of _T. +s. emoryi_ in Colorado River drainage omitted) shows that the +distribution was more widespread in former times. Localities of fossils +are centered on the Atlantic Coast from New Jersey to North Carolina and +in the Rocky Mountain-Great Plains region from Alberta and Saskatchewan +to northwestern New Mexico; the oldest fossils, which occur in each +region, are found in Upper Cretaceous deposits. Many fossils occur in +marine and brackish water deposits. Most localities depicted on the map +are mentioned by Hay (1908:36-37, 465-548). Other localities included on +the map are in southern Alberta (Russell, 1929:164; 1930:27; Sternberg, +1926:104), southern Saskatchewan (Russell, 1934:109), northern South +Dakota (Hay, 1910:324), central Utah (Gilmore, 1946), western Colorado +(Schmidt, 1945), southwestern Kansas (Galbreath, 1948:284), southeastern +Texas (Hay _in_ Stejneger, 1944:65), southern California (Brattstrom, +1958:5), and northeastern Coahuila, México (Mullerried, 1943:623). Hay's +record of the living _Platypeltis_ (= _Trionyx_) _ferox_ and other +remains from the Peace Creek formation in Hillsborough County, Florida +(_op. cit._:548), presumably is the same record mentioned by Pope +(1949:305). + + [Illustration: FIG. 24. Geographic distribution of Recent + soft-shelled turtles (bordered by heavy black line) and fossil + trionychids (black circles) in North America. The introduced + population of _T. s. emoryi_ in the southwestern United States + is not shown.] + +Ameghino (_in_ Hay, _op. cit._:35) recorded specimens of a trionychid +from the Cretaceous of Patagonia, a record that, at present, cannot be +accepted (Simpson, 1943:423). Mullerried (_loc. cit._) also mentioned +some trionychid remains that were housed in Tuxtla Gutierrez, Chiapas, +México, (material now lost), but their geographical provenance was +unknown. The former extent of range southward is not known; it is +improbable that trionychids occurred in South America (Simpson, +1943:423). + + +Phylogeny + +The occurrence of _T. ferox_ in Florida and the suggestion of +_ferox_-like characters in turtles from southwestern Texas and northern +Mexico presents a distributional pattern that resembles the disjunct +ranges of many other pairs of closely related taxa. The clear-water +ponds in central Coahuila, which are inhabited by _ater_, correspond to +aquatic habitats supporting _ferox_ in Florida. The splitting of the +geographic range into eastern and western parts possibly resulted from a +southward shift of colder climates in glacial stages of the Pleistocene, +or from the development of an intervening arid region in the late +Miocene and Pliocene (see discussions in Martin and Harrell, 1957, and +Blair, 1959). An initial separation of range by an arid environment in +the Pliocene may have been terminated by the colder climates in the +Pleistocene. + +The degree of morphological difference between _ferox_ and the forms in +southwestern Texas and northern México, suggests that the time of +separation antedated the Pleistocene. + +Trionychid turtles may have traversed the Bering land bridge between +Asia and North America in late Mesozoic times for they occur as fossils +on the Atlantic Coast and in the Rocky Mountain-Great Plains region in +Upper Cretaceous deposits. Shallow, inland seas may have afforded no +barrier to the dispersal of softshells which presumably were tolerant of +saline waters. The orogeny and volcanic action with subsequent erosion +and sedimentation of the Rocky Mountain system, which was later +accompanied by drier climates, tended to obliterate suitable habitats in +the western United States; softshells persisted at least until the Upper +Eocene on the west coast (Brattstrom, 1958:5). The factors responsible +for the disappearance of softshells on the Atlantic Coast probably were +related to the glacial advances in the Pleistocene; the most recent +fossils known occur in Miocene deposits. + +The relationships of the living species and subspecies were probably +correlated with geologic change in aquatic environments and drainage +patterns. These changes probably included stream capture, flooding, +drought, uplifting and planation. A hypothetical, evolutionary history +is presented in the phylogenetic diagram where letter symbols represent +species and subspecies, and grouped symbols (referred to in subsequent +paragraphs) represent ancestral stocks. + + Pliocene Pleistocene Recent + ========================================================================== + + +--F-----------------------------------F (_ferox_) + | + | +---------Mm (_muticus muticus_) + | +--M------------------+ + | | +---------Mc (_muticus calvatus_) + | | + FMSA-+ | +--Ss (_spinifer spinifer_) + | | +------+ + | | | +--Sh (_spinifer hartwegi_) + | | +--Ssha-+ + +--MSA-+ | | + | | +---------Sa (_spinifer asper_) + | | + | +--S---+ +--Sp (_spinifer pallidus_) + | | | +--Spg-+ + | | | | +--Sg (_spinifer guadalupensis_) + +--SA--+ +--Sepg-+ + | | + | +--Se-----Se (_spinifer emoryi_) + | + +--A---------------------A (_ater_) + + -------------------------------------------------------------------------- + +An arid environment in the central and southern United States and +northern Mexico may have increased in area especially southward from +Miocene times into the Pliocene (Dorf, 1959:189, 191). The combination +of physiographic changes and aridity, which modified the mesic, +essentially continuous, aquatic habitats, may have isolated and aided in +the differentiation of the _ferox_, _muticus_ and _spinifer_ stocks. +Encroachment of the Eocene seas, the maximal extent of which +corresponded to the Gulf Coastal Plain and included a northerly +extension as far as Cairo in southern Illinois (Mississippi embayment), +possibly was an initial barrier isolating the _ferox_ stock of the east. + +In the late Miocene or early Pliocene, the MSA (_muticus-spinifer-ater_) +stock presumably occupied a large region of the central United States, +which extended southward into northern México and along the Gulf Coast +at least as far as Alabama. Farther eastward, the _ferox_ stock was +isolated in more mesic, probably swampy, marshy habitats. + +Later, in the southwestern part of the range of the MSA stock (southern +Texas and northern México), the SA and _muticus_ stocks were separated. +The _muticus_ stock occurred to the northeastward, and presumably no +farther south than the area included within the present drainage basin +of the Colorado River. Southward, the SA stock was isolated into several +populations that are today represented by _ater_ and _T. s. emoryi_, the +most variable subspecies; the distribution of the most distinctive +population of _emoryi_ indicates a former isolated inland drainage. The +multiple fragmentation of the SA stock presumably terminated by the end +of the Pliocene. The progenitors of _T. ater_ probably closely resembled +_ferox_. _Trionyx ater_ and _T. ferox_ resemble each other +morphologically and in habitat. Therefore, the progenitors of _ater_ are +considered to have undergone comparatively little differentiation. + +The _spinifer_ stock, occurring principally in the area included within +the present drainage basin of the Río Grande, extended its geographic +range eastward and became sympatric with _muticus_ and _ferox_. An +expansion of range necessarily demands more mesic conditions; these were +perhaps afforded by the pluvials (wet, rainy ages) that were coincident +with the glacial periods in the Pleistocene (Antevs, 1948:168). The +pluvials permitted the isolated populations of the _spinifer_ stock to +unite, and permitted that stock to extend its range eastward. The +concurrent continental glaciation permitted the _spinifer_ stock to +extend its range eastward only in a belt approximately 300 miles wide +along the Gulf Coast, and also displaced the ranges of _ferox_ and +_muticus_ to southern latitudes. Perhaps _ferox_ was less tolerant of +decreased temperatures or changes in habitat than was the _spinifer_ +stock but, for some unknown reason, _ferox_ did not extend its range +westward. Because _T. ater_ closely resembles _T. s. emoryi_, continued +isolation of _ater_ since the beginning of the Pleistocene seems +unlikely and _ater_ may have been reunited in subsequent pluvial periods +with the _spinifer_ (_emoryi_) stock. A climatic fluctuation between +relatively wet and dry periods is corroborated by studies of soil +profiles in Trans-Pecos Texas (Bryan and Albritton, 1943). + +The separation of the range of _spinifer_ in the general region of +western Louisiana, resulting in the differentiation of the _spinifer_ +group of subspecies to the east and the _emoryi_ group of subspecies to +the west, and the differentiation of _T. s. asper_ and _T. m. calvatus_, +both having corresponding western limits of distribution (Mississippi +River drainage), are associated with the activities of the Mississippi +River and its flood-plain. The combined effects of the pluvials and +interpluvials seem responsible for changes in the lower Mississippi +Valley. Great volumes of summer melt-water in the glacial stages greatly +increased the breadth of the channel of the lower Mississippi River +(corresponding to the northern extent of the Mississippi embayment; +Hobbs, 1950), and this, coupled with the encroachment of Pleistocene +seas (especially in the Mississippi embayment) in the interglacial +periods, perhaps separated populations eastward represented today by _T. +m. calvatus_ and _T. s. asper_. The _spinifer-hartwegi_ stock probably +developed in southern Louisiana in association with the meandering of +the Mississippi River and its tributaries, and its broad alluvial plain. +The biota of that plain differed from that adjacent to the east or west +(see discussion in Viosca, 1944) and constituted a barrier, of a sort, +to free communication between the east and west. Westward the _emoryi_ +group of subspecies differentiated, its eastern limit probably being the +Red River, which followed its own course to the Gulf along the lowlands +on the west side of the Mississippi Valley and did not empty directly +into the Mississippi until Recent times (Holland, 1944:20). There was +not an equally-marked, corresponding separation of the range of +_muticus_. However, the juvenal pattern of the subspecies _muticus_ that +inhabits the Gulf Coast streams is slightly different (having less short +lines) from that of _muticus_ elsewhere. + +The Río Grande (inhabited by _emoryi_) presumably had its own exit to +the Gulf whereas rivers westward to (and including) the Red River +(inhabited by _pallidus-guadalupensis_ cline) probably were joined near +their mouths forming a large drainage system. Hubbs (1957:93) pointed +out that the Río Grande-Nueces divide also limits a large number of +species of fish. The differentiation of _pallidus_ and _guadalupensis_ +is possibly due to a difference in the salt content of waters that drain +the Edward's Plateau (see page 547), or to isolation of those subspecies +in separate drainage systems that had their own exits to the Gulf. + +In the lower Mississippi drainage, the _spinifer-hartwegi_ stock +extended its range northward following the retreat of the last glacial +stage, and differentiated into those two subspecies in the upper +Mississippi drainage and Great Lakes-St. Lawrence drainage system. + +I have seen one specimen (UMMZ 59198) from the eastern part of the +Tennessee drainage (inhabited by _T. s. spinifer_) that resembles _T. s. +asper_ (occupying the Gulf Coast drainages of the southeast). This +resemblance tends to support the thesis of a former confluence of the +Coosa (Alabama River system) and Tennessee drainages as believed by some +malacologists to explain resemblances in molluscan fauna and as +corroborated by physiographical evidence (see discussion in van der +Schalie, 1945). + + +The Importance of the Study of Turtle Populations in Relation to the +History of River Systems + +In the Río Grande drainage the geographic distribution of the population +of _emoryi_ having orange color in males is approximately the same as +that of _Pseudemys scripta gaigeae_; the corresponding distributions +suggest that a part of the Río Grande drainage consisting of the Río +Conchos in Chihuahua and the Big Bend region of Texas was isolated in +former times. Accordingly, the known aquatic chelonian fauna in the +basin of Cuatro Ciénegas in central Coahuila, México, is endemic (except +_T. s. emoryi_). And the coincidence of the geographic ranges of _T. +muticus calvatus_ and _Graptemys pulchra_ in the southeast suggest a +former association of the included (Pearl to Escambia) river systems. +The occurrence of _T. s. pallidus_ in the Red River drainage indicates +that the Red River was formerly associated with the Gulf Coast streams +of eastern Texas and western Louisiana (inhabited by _pallidus_) and not +with the Mississippi River drainage. The lower Mississippi River valley +forms a prominent barrier to the eastern and western dispersal of many +kinds of species and subspecies of turtles. _T. m. calvatus_ and _T. s. +asper_, which occur in rivers of the Gulf Coast drainage east of the +Mississippi, are well-differentiated subspecies showing little or no +evidence of intergradation with their relatives in the Mississippi +River. The large faunal break provided by the Mississippi River would +seem to indicate greater age for that river than for other rivers of the +Gulf Coast drainage. + +A comparison of the distributions of _Trionyx_ and _Graptemys_ in Texas +suggests a faunal break between the drainage systems of the Brazos and +Colorado rivers. _Graptemys versa_ occurs in the Colorado and +Guadalupe-San Antonio drainages. To my knowledge _versa_ hitherto has +not been recorded from the latter drainage system. I have seen one +specimen of _Graptemys_ (custody of Gerald Raun, University of Texas) +from the Guadalupe River drainage, which I judge to be representative of +_versa_, and Olson (1959:48) has reported _Graptemys_ (probably _versa_) +in the San Antonio River. The distribution of _G. versa_ parallels in a +general way, the distribution of _T. s. guadalupensis_. _G. kohni_ and +_T. s. pallidus_ occur in the Brazos River and eastward. Also, it is +notable that the population of _T. m. muticus_ occurring in the Colorado +River drainage differs slightly (more black pigmentation) from the same +subspecies in the adjacent Brazos River system. + +There is much difference in the patterns of distribution and degree of +differentiation of different genera of aquatic turtles in the eastern +United States. Tinkle (1958:41-43, Figs. 49-55) concluded that a general +resemblance in the patterns of distribution of the different genera of +turtles was evidence that the rates of evolution were essentially the +same, assuming that each genus had had a similar time interval for +differentiation (_op. cit._:42). If this is true, corresponding patterns +of distribution might indicate the same relative age of the population +of turtles concerned. Generally, the genera of turtles that on +morphological grounds are considered the oldest and most primitive +(_Macroclemys_, _Chelydra_) show less differentiation into species and +subspecies than those considered younger and more recently evolved +(_Graptemys_, _Pseudemys_). In the genus _Graptemys_, much +differentiation occurs in the geologically, recently formed, Gulf Coast +drainage systems of the southeastern United States. It would seem then, +that faster rates of differentiation denote more recent genera, whereas +older genera are endowed with a "genetic senility" and are less subject +to change. + +Evidence of the relative age of two genera of turtles, as suggested by +their degree of differentiation into minor taxa, and the degree of +difference between populations of two genera that inhabit adjacent +drainage systems, may indicate the relative ages of particular river +systems. For example, the slight resemblance of _G. versa_ to _kohni_ +and the close resemblance of _T. s. guadalupensis_ to _pallidus_ in +Texas may reflect the age of the genus _Trionyx_ and the youth of the +genus _Graptemys_. Remembering that the genus _Graptemys_ is relatively +recently evolved and assuming _G. versa_ to be the most primitive and +ancestral species of the genus (at least it is monotypic, the most +aberrant species, and unlike any other species of the genus), it seems +logical to suppose that the physiographic changes responsible for the +Colorado-Brazos divide and the isolation of _versa_ occurred early in +the evolutionary history of the genus _Graptemys_. The degree of +differentiation of _Trionyx_ suggests that that genus is, comparatively, +much older, and that the same physiographic changes responsible for the +Colorado-Brazos divide and differentiation of the subspecies _pallidus_ +and _guadalupensis_ occurred late in the evolutionary history of the +genus _Trionyx_. + +In general, patterns of distribution of turtle populations support +physiographic evidence concerning changes in stream confluence and +relative age of river systems. + + + + +SUMMARY + + +In North America, soft-shelled turtles (genus _Trionyx_) occur in +northern México, the eastern two-thirds of the United States, and +extreme southeastern Canada. The genus fits the well-known Sino-American +distributional pattern. In North America there are four species. Three +(_ferox_, _spinifer_ and _muticus_) are well-differentiated and one +(_ater_) is not well-differentiated from _spinifer_. Characters of +taxonomic worth are provided by the following: size; proportions of +snout, head and shell; pattern on carapace, snout, side of head, and +limbs; tuberculation; sizes of parts of skull; number of parts of +carapaces; and, shape and number of some parts of plastra. Many features +show geographical gradients or clines. _T. ferox_ is the largest species +and _muticus_ is the smallest. Females of all species are larger than +males. With increasing size of individual, the juvenal pattern is +replaced by a mottled and blotched pattern in females of all species; +adult males of _spinifer_ retain a conspicuous juvenal pattern, whereas +the juvenal pattern is sometimes obscured or lost on those of _ferox_ +and _muticus_. The elongation of the preanal region in all males, and +the acquisition of a "sandpapery" carapace in males of _spinifer_ occur +at sexual maturity. There is a marked secondary sexual difference in +coloration in a population of _T. s. emoryi_ (side of head bright orange +in males and yellow in females). The sex of many hatchlings of _T. s. +asper_ can be distinguished by the pattern on the carapace. Slight +ontogenetic variation occurs in some proportional measurements. Large +skulls of _ferox_ and some _asper_ (those in Atlantic Coast drainages) +have expanded crushing surfaces on the jaws. Considering osteological +characters, _muticus_ is most distinct; there is less difference between +_ferox_ and _spinifer_ than between those species and _muticus_. + +_T. ferox_ is monotypic, confined to the southeastern United States, and +resembles Old World softshells more than it does any American species. +The northern part of the geographic range of _ferox_ overlaps that of +_T. s. asper_; there, the two species are ecologically isolated. _T. +spinifer_ is polytypic, has the largest geographic range, and is +composed of six subspecies, of which two are described as new +(_pallidus_ and _guadalupensis_). The subspecies are divisible into two +groups. One, the _spinifer_ group (_spinifer_, _hartwegi_ and _asper_) +is recognized by a juvenal pattern having black spots or ocelli; _asper_ +is the most distinctive and shows little evidence of intergradation in +the lower Mississippi River drainage with the _spinifer-hartwegi_ +complex, which, northward, is differentiated into two subspecies in +which there is an east-west cline in size of the ocelli on the carapace. +The _emoryi_ group (_pallidus_, _guadalupensis_, _emoryi_) is recognized +by a pattern of white spots; _emoryi_ is most distinctive. Each of +several characters behaves as a cline if traced from east to west +through the three subspecies. _T. s. pallidus_ intergrades with the +_spinifer-hartwegi_ complex in the lower Mississippi River drainage. _T. +s. emoryi_ is the most variable subspecies; in its most notable +population the males have orange coloration. _T. s. emoryi_ has been +introduced into the Colorado River drainage of Arizona. _T. ater_ most +closely resembles _T. s. emoryi_, but shows alliance with _T. muticus_ +and _T. ferox_. _T. ater_ is confined to ponds of crystal-clear water in +central Coahuila, México. _T. muticus_ is completely sympatric with +_spinifer_, and is composed of two subspecies (_muticus_ and +_calvatus_). _T. m. calvatus_ shows no evidence of intergradation in the +lower Mississippi River drainage with _T. m. muticus_, corresponding +somewhat to the relationship of _T. s. asper_ with the intergradient +population of _T. spinifer_ in the Mississippi River. + +Softshells have pharyngeal respiration and probably are incapacitated by +rotenone. _T. ferox_ and the subspecies of _spinifer_ occur in a wide +variety of fresh-water habitats; _muticus_ is more nearly restricted to +running water (especially in the northern parts of its range) than +_spinifer_, and may be less vagile than _spinifer_. _T. ferox_ is more +tolerant of marine and brackish waters than are _muticus_ or _spinifer_. +Small size and pallid coloration seem correlated with arid environments. +The largest species (_ferox_) and the smallest population of _spinifer_ +(resembling _muticus_) both occur in the southernmost part of the range +of the genus. Diurnal habits include basking on shores or débris in +water, floating at the surface, procuring food, and burrowing in shallow +and deep water (no observations for _spinifer_ and _muticus_ in deep +water). Softshells are principally carnivorous; the food consists mostly +of crawfish and insects; there is evidence of cannibalism involving +predation on first- and second-year-old turtles. The capture of food is +triggered primarily by movement of prey; sight seems to be more +important than smell to _Trionyx_ in capturing food. There is no +indication of a food preference between species; enlarged crushing +surfaces of jaws in some _ferox_ and _asper_ may be an adaptation for +feeding on mollusks. Schools of fish are reported to follow softshells, +and presumably acquire food that is dislodged by the grubbing and +scurrying of the turtles on the bottom. Softshells are wary. They are +good swimmers, and travel rapidly on land. The depressed body is an +adaptation for burrowing and concealment. Permanent growths of algae do +not occur on the dorsal surface of softshells. There is evidence of some +nocturnal activity, and a general parallel in habits between trionychids +and chelydrids. Softshells sometimes move overland; they move little in +aquatic habitats. The normal annual period of activity of _spinifer_ in +latitudes 40° to 43° is approximately five months from April into +September, depending on the weather; they hibernate under a shallow +covering of mud in deep water. The southernmost populations may be +active throughout the year. + +Males of _spinifer_ are sexually mature when the plastron is 9.0 to 10.0 +centimeters in length (some when 8.0 long), whereas those of _muticus_ +are sexually mature at 8.0 to 9.0 centimeters. In the mentioned size +range, the smaller adult males are probably in their fourth growing +season, and the larger males in their fifth. Most females of _spinifer_ +are sexually mature at a plastral length of 18.0 to 20.0 centimeters and +are probably in their ninth year; the smaller individuals probably are +in their eighth. Females of _muticus_ are sexually mature when the +plastron is 14.0 to 16.0 centimeters long. Most of these are seven years +old but some are only six years old. Some large females contain immature +ovaries. The near-maximum length of carapace of _spinifer_ is 18 inches, +and such turtles are perhaps 60 years old; _ferox_ perhaps attains a +length of two feet. + +_T. ferox_ deposits eggs from late March to mid-July, whereas northern +populations of _spinifer_ and _muticus_ usually deposit theirs from +mid-June to mid-July. Sandy sites are preferred for nests, although +movement to other sites occurs if the preferred sandy sites are +submerged or otherwise rendered unusable. _T. muticus_ limits its nest +sites to the open areas of sand bars and does not lay inland where it +must traverse vegetated areas, as does _spinifer_. Nests of _ferox_ and +_spinifer_ seem to differ from those of _muticus_ in being flask-shaped. + +The seasonal reproductive potential is perhaps less in northern +populations (averaging 20 eggs per clutch and only one clutch per +season) than in southern populations (averaging about 10 eggs per +clutch, but three clutches per season). Larger females deposit more eggs +than smaller females. Eggs laid in northern latitudes are slightly +smaller than those laid farther south. In any latitude the incubation +period probably is at least 60 days. Hatchlings presumably leave nests +at dusk, nighttime or dawn, and may winter over in eggs or nests. + +Man is a great enemy of softshells. Predation on eggs probably accounts +for most mortality. Physical conditions of the environment (overcrowding +of nest sites, inadequate hibernation sites) and probably some kinds of +parasitism contribute to mortality. Softshells are eaten locally and +sometimes appear in the market of large cities, but over most of their +range, there probably is no general demand and no special efforts are +made to capture them. Fish, mostly minnows, comprise a small proportion +of the diet. There is no evidence that softshells are active predators +on any kind of fish, but their known food habits suggest that they +compete with game fishes for food. Softshells are scavengers. + +Fossil material was not studied in detail. The fossil softshells +indicate a more widespread, former distribution. Some osteological +characters and their variation in the living species are mentioned as an +aid to future workers concerned with an assay of fossil remains. Fossils +occur in marine, brackish and fresh-water deposits, and many are much +larger than the living species; the oldest American fossils are of Upper +Cretaceous age. + +The interrelationships of the living species and subspecies suggest that +the species _spinifer_, _ater_, and _muticus_ are derivatives of a +_ferox_-like ancestor, and that they differentiated in North America; +most differentiation occurs in southwestern Texas and northern México +where characters of some populations indicate alliance with _ferox_. It +is hypothesized that aridity in the late Tertiary effected specific +differentiation by the modification and isolation of aquatic habitats. +Pluvial periods in the Pleistocene provided for confluence of aquatic +habitats and expansion of geographic ranges, and coupled with +physiographic changes, conceivably caused or enhanced some of the +subspecific variation. + + + + +LITERATURE CITED + + +References marked with an asterisk were not seen by the author. + + ADAMS, M. S., and CLARK, H. F. + + 1958. A herpetofaunal survey of Long Point, Ontario, Canada. + Herpetologica, 14(1):8-10, April 25. + + + ADLER, K. K., and DENNIS, D. M. + + 1960. New herpetological records from Ohio. Jour. Ohio Herp. Soc., + 2(4):25-27. + + + AGASSIZ, L. + + 1857. Contributions to the natural history of the United States of + America. Vol. I. Part II. North American Testudinata. Vol. II. + Part III. Embryology of the turtle. 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A., and CARR, K. + + + 1939. Amphibians and reptiles of northeastern Kentucky. Copeia, + 1939 (3):128-30, September 9. + + + WHEELER, G. C. + + + 1947. The amphibians and reptiles of North Dakota. Amer. Midl. + Nat., 38(1):162-90, July. + + + WIED-NEUWIED, M. A. P. + + + * 1838. Reise in das innere Nord-America in den Jahren 1832 bis + 1834. Reise von Bethlehem nach Pittsburgh über die + Alleghanys, vom 17. September bis zum 7. October. Coblenz, + pp. 121-42 (from Carr, 1952:527). + + 1865. Verziechniss der reptilien welche auf einer reise im + nordlichen America beobachtet wurden. Nova Acta Acad. + Leopold.--Carol., 32:viii + 146, 7 pls. + + + WILLIAMS, E. E. + + + 1950. Variation and selection in the cervical central articulations + of living turtles. Bull. Amer. Mus. Nat. Hist., + 94(9):509-61, 20 figs., 10 tables, March 24. + + + WILLIAMS, E. E., and MCDOWELL, S. B. + + + 1952. The plastron of soft-shelled turtles (Testudinata, + Trionychidae): a new interpretation. Jour. Morph., + 90(2):263-75, 2 pls., March. + + + WILLIAMS, K. L. + + + 1957. Yolk retraction as a possible cause of kyphosis in turtles. + Herpetologica, 13(Pt. 3):236, October 31. + + + WOOD, L. W. + + + 1959. New Ohio county records in the herpetology collection of the + Cleveland Museum of Natural History. Jour. Ohio Herp. Soc., + 2(2):8, September. + + + WRIGHT, A. H. + + + 1919. The turtles and the lizard of Monroe and Wayne counties, New + York. Copeia, 1919(66):6-8, February 25. + + + WRIGHT, A. H., and FUNKHOUSER, W. D. + + + 1915. A biological reconnaissance of the Okefinokee Swamp in + Georgia. The reptiles. Proc. Acad. Nat. Sci., Phila., + 67:107-92, 14 figs., 3 pls., April 23. + + + YARROW, H. C. + + + 1882. Check list of North American Reptilia and Batrachia, with + catalogue of specimens in the U. S. National Museum. Bull. + U. S. Nat. Mus., 24:vi + 249 pp. + + + ZANGERL, R. + + + 1939. The homology of the shell elements in turtles. Jour. Morph., + 65(3):383-407, 9 figs., 2 pls., November. + + +_Transmitted June 8, 1961._ + + + + + [Illustration: PLATE 31 + + _Trionyx ferox_, juveniles. _Top_--UMMZ 76755 (× 1) dorsal and + ventral views; Lake Griffin, Lake County, Florida. _Bottom_--TU + 13960 (× 3/4), dorsal and ventral views; Hillsborough River, + _ca._ 20 mi. NE Tampa, Hillsborough County, Florida.] + + [Illustration: PLATE 32 + + _Top_--_Trionyx ferox_, female, UMMZ 90010 (× 2/9); east edge + Okefinokee Swamp, Charlton County, Georgia. _Bottom_--Left, + _Trionyx ferox_, adult male, UMMZ 102276 (× 1/5), 14 mi. SE Punta + Gorda, Lee County, Florida; right, _Trionyx sinensis_, female, KU + 39417 (× 3/10), 5 mi. ESE Seoul, Korea. All dorsal views; note + resemblance of two species in having longitudinal ridging and + marginal ridge of carapace.] + + [Illustration: PLATE 33 + + _Trionyx spinifer spinifer_, juveniles, dorsal views. + _Top_--UMMZ 74518 (× 1-2/5); Portage Lake, Washtenaw County, + Michigan. + _Bottom_--TU 16132 (× 1-1/5); Sevierville, Sevier County, + Tennessee.] + + [Illustration: PLATE 34 + + _Trionyx spinifer spinifer_, dorsal views. + _Top_--Adult male, UMMZ 54401 (× 3/7), Portage Lake, + Livingston County, Michigan. + _Bottom_--Female, UMMZ 81699 (× 2/7), Ottawa County, Michigan.] + + [Illustration: PLATE 35 + + _Trionyx spinifer hartwegi_, dorsal views. + _Top_--Juveniles; left, KU 40210 (× 9/10), 12-1/2 mi. + S, 1-1/4 mi. W Meade, Meade County, Kansas; right, KU 16531 + (× 1), Smoky Hill River, 3 mi. SW Elkader, Logan County, Kansas. + _Bottom_--Adult Males; left, KU 18385 (× 2/5), Arrington, + Comanche County, Kansas; right, KU 3758 (× 3/10), + Little Salt Marsh, Stafford County, Kansas.] + + [Illustration: PLATE 36 + + _Trionyx spinifer hartwegi._ + _Top_--Juveniles; left, TU 13885, dorsal view (× 3/4), + Little Vian Creek, 1 mi. E Vian, Sequoyah County, Oklahoma; + right, KU 3732, ventral view (× 5/7), Independence, + Montgomery County, Kansas. + _Bottom_--Adult female, TTC 719, dorsal view (× 2/7), 10 mi. S, + 2 mi. W Gruver, Hansford County, Texas.] + + [Illustration: PLATE 37 + + _Trionyx spinifer asper_, juveniles, dorsal views. + _Top_--Left, male, KU 50839 (× 9/10), Flint River, 1-1/2 mi. S + Bainbridge, Decatur County, Georgia; right, female, TU 15661 + (× 9/10), Blackwater River, 4.3 mi. NW Baker, Okaloosa County, + Florida. + _Bottom_--Left, male, TU 13623 (× 7/9), Yellow River, 3.1 mi. W + Hammond, Tangipahoa Parish, Louisiana; right, female, TU 14362 + (× 4/5), Hobolochito Creek, 1 mi. N Picayune, Pearl River County, + Mississippi.] + + [Illustration: PLATE 38 + + _Trionyx spinifer asper_, dorsal views. + _Top_--Left, adult male, TU 15869 (× 1/2), Escambia River, 1.2 mi. E + Century, Escambia County, Florida; right, female, TU 14673.3 + (× 1/2), Black Warrior River, 17-1/2 mi. SSW Tuscaloosa, + Tuscaloosa County, Alabama. + _Bottom_--Left, adult male, TU 17117 (× 1/4), Pearl River, + Varnado, Washington Parish, Louisiana; right, female, TU 16584 + (× 1/5), locality same as TU 15869.] + + [Illustration: PLATE 39 + + _Trionyx spinifer pallidus_, new subspecies, dorsal views. + _Top_--Juveniles; left, TU 481 (× 2/3), Caddo Lake, Caddo Parish, + Louisiana; right, KU 50832 (× 9/10), mouth of Caney Creek, 4 mi. + SW Kingston, Marshall County, Oklahoma. + _Bottom_--Adult males; left, holotype, TU 484 (× 1/3), locality + same as TU 481; right, TU 1122 (× 2/9), Lacassine Refuge, + Cameron Parish, Louisiana.] + + [Illustration: PLATE 40 + + _Trionyx spinifer pallidus_, new subspecies, dorsal views. + _Top_--Females; left, TU 13213 (× 1/4), Sabine River, 8 mi. SW + Negreet, Sabine Parish, Louisiana; right, TU 13266 (× 2/9), + Sabine River, 8 mi. SW Merryville, Beauregard Parish, Louisiana. + _Bottom_--Left, adult male, SM 2889 (× 1/4), Groveton, Trinity + County, Texas; right, female, TU 14402 (× 1/5), Trinity River, + near junction with Big Creek, Liberty County, Texas.] + + [Illustration: PLATE 41 + + _Trionyx spinifer guadalupensis_, new subspecies, dorsal views. + _Top_--Juveniles; left, ANSP 16717 (× 1), no data; right, KU + 50834 (× 1-1/10), Hondo Creek, 4 mi. W Bandera, Bandera County, + Texas. + _Bottom_--Adult males; left, holotype UMMZ 89926 (× 1/3), 15 mi. + NE Tilden, McMullen County, Texas; right, SM 659 (× 3/10), + Colorado River, near Austin, Travis County, Texas.] + + [Illustration: PLATE 42 + + _Trionyx spinifer guadalupensis_, new subspecies, dorsal views. + _Top_--Adult females; left, TU 16036.1 (× 1/5), Llano River, + 2 mi. W Llano, Llano County, Texas; right, TU 10160 (× 1/5), + Guadalupe River, 9 mi. SE Kerrville, Kerr County, Texas. + _Bottom_--Left, female, CM 3118 (× 3/4), Black Bayou, Victoria + County, Texas; right, male, TU 14419.6 (× 5/9), San Saba River, + 11 mi. NNW San Saba, San Saba County, Texas.] + + [Illustration: PLATE 43 + + _Trionyx spinifer emoryi_, dorsal views. + _Top_--Juveniles; left, UMMZ 69411 (× 3/4), Río Conchos, 9 mi. + N Linares, Nuevo León, México; right, UMMZ 69412 (× 5/6), + Río Purificación, north Ciudad Victoria, Tamaulipas, México. + _Bottom_--Adult males; left, topotype, TU 11561 (× 1/3), + Brownsville, Cameron County, Texas; right, KU 48217 (× 1/3), + Black River Village, Eddy County, New Mexico.] + + [Illustration: PLATE 44 + + _Trionyx spinifer emoryi_, dorsal views. _Top_--Left, adult male, + KU 51194 (× 2/7), Río Conchos, near Meoquí, Chihuahua, México; + right, female, KU 3119 (× 4/9), Salt River, Phoenix, Maricopa + County, Arizona. + _Bottom_--Females; left, KU 3118 (× 1/5), locality same as KU 3119; + right, TU 14453 (× 3/10), Pecos River, near junction with + Independence Creek, Terrell County, Texas.] + + [Illustration: PLATE 45 + + _Trionyx muticus muticus_, juveniles, dorsal views. + _Top_--Topotypes (× 1), Wabash River, 2 mi. S New Harmony, Posey + County, Indiana; left, INHS 7278; right, INHS 7279. + _Bottom_--Left, TU 14375 (× 3/4), Trinity River near junction with + Big Creek, Liberty County, Texas; right, KU 50845 (× 1-2/5), + 4 mi. N Atwood, Hughes County, Oklahoma.] + + [Illustration: PLATE 46 + + _Trionyx muticus muticus_, dorsal views. + _Top_--Adult males; left, TU 14606 (× 3/10), White River, Cotter, + Marion County, Arkansas; right, KU 48237 (× 1/3), 8 mi. S + Hanover, Washington County, Kansas. + _Bottom_--Females (× 1/4), 2 mi. E Manhattan, in Pottawatomie + County, Kansas; left, KU 48229; right, KU 48238.] + + [Illustration: PLATE 47 + + _Trionyx muticus calvatus_, dorsal views. + _Top_--Juvenile, TU 17303 (× 1-2/5), Pearl River, Varnado, + Washington Parish, Louisiana. + _Bottom_--Left, adult male, KU 47118 (× 3/10), Pearl River within + 4 mi. of Monticello, Lawrence County, Mississippi; right, adult + female, TU 17306 (× 2/9), Pearl River, 9 mi. S Monticello, + Lawrence County, Mississippi.] + + [Illustration: PLATE 48 + + FIG. 1. Habitat of _T. s. pallidus_, Little River, 6.5 mi. S + Broken Bow, McCurtain County, Oklahoma, September 7, 1953. + + FIG. 2. Habitat of _T. s. emoryi_, Río Mesquites, 2 mi. W + Nadadores, Coahuila, México, July 27, 1959. Two _emoryi_ were + trapped in hoop nets set in quiet water to left of what is + believed to be a muskrat house.] + + [Illustration: PLATE 49 + + FIG. 1. General habitat of _T. s. pallidus_ and _T. m. muticus_, + Lake Texoma, in a period of low water, 2 mi. E Willis, Marshall + County, Oklahoma, February 24, 1951. + + FIG. 2. Type locality of _T. ater_, Tío Candido, 16 km. S Cuatro + Ciénegas, Coahuila, México, July 30, 1959. An adult male of + _T. s. emoryi_ was also netted here.] + + [Illustration: PLATE 50 + + FIG. 1. General habitat of _T. s. asper_ and _T. m. calvatus_, + Escambia River, 2 mi. E, 1/2 mi. N Century, Escambia County, + Florida, June 1, 1954. Three nests of _calvatus_ found on + sand bar in foreground.] + + FIG. 2. Nest site of _T. m. calvatus_ (excavated by investigator) + on open sand bar shown above in Fig. 1, June 1, 1954. Note + tracks of turtle in foreground leading toward and away + from disturbed area at left. + + [Illustration: PLATE 51 + + FIG. 1. Eggs of _T. m. calvatus in situ_, June 1, 1954, + approximately six inches below surface, from nest shown in + Fig. 2, Pl. 50. Note sandy substrate and seemingly irregular + arrangement of eggs. + + FIG. 2. Eggs of _T. m. calvatus in situ_, June 1, 1954; nest + located at brim of incline shown in foreground of Fig. 1, + Pl. 50. Note gravelly substrate (in foreground) and + symmetrical arrangement of eggs.] + + [Illustration: PLATE 52 + + Lectotype of _Trionyx spinifer_ Lesueur, Museum d'Histoire + Naturelle, Paris, No. 8808 (× 1/5); obtained by C. A. Lesueur + from the Wabash River, New Harmony, Posey County, Indiana. + _Top_--Dorsal view. _Bottom_--Ventral view.] + + [Illustration: PLATE 53 + + Lectotype of _Trionyx muticus_ Lesueur, Museum d'Histoire + Naturelle, Paris, No. 8813 (× 1/2); obtained by C. A. Lesueur + from the Wabash River, New Harmony, Posey County, Indiana. + _Top_--Dorsal view. + _Bottom_--Ventral view.] + + [Illustration: PLATE 54 + + Skull of holotype of _Platypeltis agassizi_ Baur (= _T. s. asper_), + MCZ 37172 (× 1), Savannah River, Georgia. + _Top_--Dorsal view. + _Bottom_--Ventral view.] + + +28-7818 + + + +UNIVERSITY OF KANSAS PUBLICATIONS + +MUSEUM OF NATURAL HISTORY + +Institutional libraries interested in publications exchange may obtain +this series by addressing the Exchange Librarian, University of Kansas +Library, Lawrence, Kansas. Copies for individuals, persons working in a +particular field of study, may be obtained by addressing instead the +Museum or Natural History, University of Kansas, Lawrence, Kansas. There +is no provision for sale of this series by the University Library, which +meets institutional requests, or by the Museum of Natural History, which +meets the requests of individuals. However, when individuals request +copies from the Museum, 25 cents should be included, for each separate +number that is 100 pages or more in length, for the purpose of defraying +the costs of wrapping and mailing. + +* An asterisk designates those numbers of which the Museum's supply (not +the Library's supply) is exhausted. Numbers published to date, in this +series, are as follows: + + Vol. 1. Nos. 1-26 and index. Pp. 1-638, 1946-1950. + + *Vol. 2. (Complete) Mammals of Washington. By Walter W. Dalquest. Pp. 1-444, 140 + figures in text. April 9, 1948. + + Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and + distribution. By Rollin H. Baker. Pp. 1-359, 16 figures + in text. June 12, 1951. + + *2. A quantitative study or the nocturnal migration of + birds. By George H. Lowery, Jr. Pp. 361-472, 47 figures + in text. June 29, 1951. + + 3. Phylogeny of the waxwings and allied birds. By M. Dale + Arvey. Pp. 473-530, 49 figures in text, 13 tables. + October 10, 1951. + + 4. Birds from the state of Veracruz, Mexico. By George H. + Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7 + figures in text, 2 tables. October 10, 1951. + + Index. Pp. 651-681. + + *Vol. 4. (Complete) American weasels. By E. Raymond Hall. Pp. 1-466, + 41 plates, 31 figures in text. December 27, 1951. + + Vol. 5. Nos. 1-37 and index. Pp. 1-676, 1951-1953. + + *Vol. 6. (Complete) Mammals of Utah, _taxonomy and distribution_. + By Stephen D. Durrant. Pp. 1-549, 91 figures in text, + 30 tables. August 10, 1952. + + Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, + 73 figures in text, 37 tables. August 25, 1952. + + 2. Ecology of the opossum on a natural area in northeastern + Kansas. By Henry S. Fitch and Lewis L. Sandidge. Pp. + 305-338, 5 figures in text. August 24, 1953. + + 3. The silky pocket mice (Perognathus flavus) of Mexico. By + Rollin H. Baker. Pp. 339-347, 1 figure in text. + February 15, 1954. + + 4. North American jumping mice (Genus Zapus). By Phillip H. + Krutzsch. Pp. 349-472, 47 figures in text, 4 tables. + April 21, 1954. + + 5. Mammals from Southeastern Alaska. By Rollin H. Baker and + James S. Findley. Pp. 473-477. April 21, 1954. + + 6. Distribution of Some Nebraskan Mammals. By J. Knox + Jones, Jr. Pp. 479-487. April 21, 1954. + + 7. Subspeciation in the montane meadow mouse, Microtus + montanus, in Wyoming and Colorado. By Sydney Anderson. + Pp. 489-506, 2 figures in text. July 23, 1954. + + 8. A new subspecies of bat (Myotis velifer) from + southeastern California and Arizona. By Terry A. + Vaughan. Pp. 507-512. July 23, 1954. + + 9. Mammals of the San Gabriel mountains of California. By + Terry A. Vaughan. Pp. 513-582, 1 figure in text, 12 + tables. November 15, 1954. + + 10. A new bat (Genus Pipistrellus) from northeastern + Mexico. By Rollin H. Baker. Pp. 583-586. November 15, + 1954. + + 11. A new subspecies of pocket mouse from Kansas. By E. + Raymond Hall. Pp. 587-590. November 15, 1954. + + 12. Geographic variation in the pocket gopher, Cratogeomys + castanops, in Coahuila, Mexico. By Robert J. Russell + and Rollin H. Baker. Pp. 591-608. March 15, 1955. + + 13. A new cottontail (Sylvilagus floridanus) from + northeastern Mexico. By Rollin H. Baker. Pp. 609-612. + April 8, 1955. + + 14. Taxonomy and distribution of some American shrews. By + James S. Findley. Pp. 613-618. June 10, 1955. + + 15. The pigmy woodrat, Neotoma goldmani, its distribution + and systematic position. By Dennis G. Rainey and Rollin + H. Baker. Pp. 619-624, 2 figures in text. June 10, + 1955. + + Index. Pp. 625-651. + + Vol. 8. Nos. 1-10 and index. Pp. 1-675, 1954-1956. + + Vol. 9. 1. Speciation of the wandering shrew. By James S. Findley. + Pp. 1-68, 18 figures in text. December 10, 1955. + + 2. Additional records and extension of ranges of mammals + from Utah. By Stephen D. Durrant, M. Raymond Lee, and + Richard M. Hansen. Pp. 69-80. December 10, 1955. + + 3. A new long-eared myotis (Myotis evotis) from + northeastern Mexico. By Rollin H. Baker and Howard J. + Stains. Pp. 81-84: December 10, 1955. + + 4. Subspeciation in the meadow mouse, Microtus + pennsylvanicus, in Wyoming. By Sydney Anderson. Pp. + 85-104, 2 figures in text. May 10, 1956. + + 5. The condylarth genus Ellipsodon. By Robert W. Wilson. + Pp. 105-116, 6 figures in text. May 19, 1956. + + 6. Additional remains of the multituberculate genus + Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 + figures in text. May 19, 1956. + + 7. Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp. + 125-335, 75 figures in text. June 15, 1956. + + 8. Comments on the taxonomic status of Apodemus peninsulae, + with description of a new subspecies from North China. + By J. Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1 + table. August 15, 1956. + + 9. Extension of known ranges of Mexican bats. By Sydney + Anderson. Pp. 347-351. August 15, 1956. + + 10. A new bat (Genus Leptonycteris) from Coahuila. By + Howard J. Stains. Pp. 353-356. January 21, 1957. + + 11. A new species of pocket gopher (Genus Pappogeomys) from + Jalisco, Mexico. By Robert J. Russell. Pp. 357-361. + January 21, 1957. + + 12. Geographic variation in the pocket gopher, Thomomys + bottae, in Colorado. By Phillip M. Youngman. Pp. + 363-387, 7 figures in text. February 21, 1958. + + 13. New bog lemming (genus Synaptomys) from Nebraska. By J. + Knox Jones, Jr. Pp. 385-388. May 12, 1958. + + 14. Pleistocene bats from San Josecito Cave, Nuevo León, + México. By J. Knox Jones, Jr. Pp. 389-396. December 19, + 1958. + + 15. New subspecies of the rodent Baiomys from Central + America. By Robert L. Packard. Pp. 397-404. December + 19, 1958. + + 16. Mammals of the Grand Mesa, Colorado. By Sydney + Anderson. Pp. 405-414, 1 figure in text, May 20, 1959. + + 17. Distribution, variation, and relationships of the + montane vole, Microtus montanus. By Sydney Anderson. + Pp. 415-511, 12 figures in text, 2 tables. August 1, + 1959. + + 18. Conspecificity of two pocket mice, Perognathus goldmani + and P. artus. By E. Raymond Hall and Marilyn Bailey + Ogilvie. Pp. 513-518, 1 map. January 14, 1960. + + 19. Records of harvest mice, Reithrodontomys, from Central + America, with description of a new subspecies from + Nicaragua. By Sydney Anderson and J. Knox Jones, Jr. + Pp. 519-529. January 14, 1960. + + 20. Small carnivores from San Josecito Cave (Pleistocene), + Nuevo León, México. By E. Raymond Hall. Pp. 531-538, 1 + figure in text. January 14, 1960. + + 21. Pleistocene pocket gophers from San Josecito Cave, + Nuevo León, México. By Robert J. Russell. Pp. 539-548, + 1 figure in text. January 14, 1960. + + 22. Review of the insectivores of Korea. By J. Knox Jones, + Jr., and David H. Johnson. Pp. 549-578. February 23, + 1960. + + 23. Speciation and evolution of the pygmy mice, genus + Baiomys. By Robert L. Packard. Pp. 579-670, 4 plates, + 12 figures in text. June 16, 1960. + + Index. Pp. 671-690. + + Vol. 10. 1. Studies of birds killed in nocturnal migration. By + Harrison B. Tordoff and Robert M. Mengel. Pp. 1-44, + 6 figures in text, 2 tables. September 12, 1956. + + 2. Comparative breeding behavior of Ammospiza caudacuta + and A. maritima. By Glen E. Woolfenden. Pp. 45-75, + 6 plates, 1 figure. December 20, 1956. + + 3. The forest habitat of the University of Kansas Natural + History Reservation. By Henry S. Fitch and Ronald R. + McGregor. Pp. 77-127, 2 plates, 7 figures in text, + 4 tables. December 31, 1956. + + 4. Aspects of reproduction and development in the prairie + vole (Microtus ochrogaster). By Henry S. Fitch. Pp. + 129-161, 8 figures in text, 4 tables. December 19, + 1957. + + 5. Birds found on the Arctic slope of northern Alaska. + By James W. Bee. Pp. 163-211, plates 9-10, 1 figure + in text. March 12, 1958. + + 6. The wood rats of Colorado: distribution and ecology. By + Robert B. Finley, Jr. Pp. 213-552, 34 plates, 8 figures + in text, 35 tables. November 7, 1958. + + 7. Home ranges and movements of the eastern cottontail + in Kansas. By Donald W. Janes. Pp. 553-572, 4 plates, + 3 figures in text. May 4, 1959. + + 8. Natural history of the salamander, Aneides hardyi. By + Richard F. Johnston and Gerhard A. Schad. Pp. 573-585. + October 8, 1959. + + 9. A new subspecies of lizard, Cnemidophorus sacki, from + Michoacán, México. By William E. Duellman. Pp. 587-598, + 2 figures in text. May 2, 1960. + + 10. A taxonomic study of the Middle American Snake, + Pituophis deppei. By William E. Duellman. Pp. 599-610, + 1 plate, 1 figure in text. May 2, 1960. + + Index. Pp. 611-626. + + Vol. 11. 1. The systematic status of the colubrid snake, + Leptodeira discolor Günther. By William E. Duellman. + Pp. 1-9, 4 figures. July 14, 1958. + + 2. Natural history of the six-lined racerunner, + Cnemidophorus sexlineatus. By Henry S. Fitch. + Pp. 11-62, 9 figures, 9 tables. September 19, 1958. + + 3. Home ranges, territories, and seasonal movements of + vertebrates of the Natural History Reservation. By + Henry S. Fitch. Pp. 63-326, 6 plates, 24 figures in + text, 3 tables. December 12, 1958. + + 4. A new snake of the genus Geophis from Chihuahua, + Mexico. By John M. Legler. Pp. 327-334, 2 figures + in text. January 28, 1959. + + 5. A new tortoise, genus Gopherus, from north-central + Mexico. By John M. Legler. Pp. 335-343. April 24, 1959. + + 6. Fishes of Chautauqua, Cowley and Elk counties, Kansas. + By Artie L. Metcalf. Pp. 345-400, 2 plates, 2 figures + in text, 10 tables. May 6, 1959. + + 7. Fishes of the Big Blue river basin, Kansas. By W. L. + Minckley. Pp. 401-442, 2 plates, 4 figures in text, + 5 tables. May 8, 1959. + + 8. Birds from Coahuila, México. By Emil K. Urban. + Pp. 443-516. August 1, 1959. + + 9. Description of a new softshell turtle from the + southeastern United States. By Robert G. Webb. + Pp. 517-525, 2 plates, 1 figure in text. + August 14, 1959. + + 10. Natural history of the ornate box turtle, Terrapene + ornata ornata Agassiz. By John M. Legler. Pp. 527-669, + 16 pls., 29 figures in text. March 7, 1960. + + Index Pp. 671-703. + + Vol. 12. 1. Functional morphology of three bats: Eumops, Myotis, + Macrotus. By Terry A. Vaughan. Pp. 1-153, 4 plates, + 24 figures in text. July 8, 1959. + + 2. The ancestry of modern Amphibia: a review of the + evidence. By Theodore H. Eaton, Jr. Pp. 155-180, + 10 figures in text. July 10, 1959. + + 3. The baculum in microtine rodents. By Sydney Anderson. + Pp. 181-216, 49 figures in text. February 19, 1960. + + 4. A new order of fishlike Amphibia from the Pennsylvanian + of Kansas. By Theodore H. Eaton, Jr., and Peggy Lou + Stewart. Pp. 217-240, 12 figures in text. May 2, 1960. + + More numbers will appear in volume 12. + + Vol. 13. 1. Five natural hybrid combinations in minnows (Cyprinidae). + By Frank B. Cross and W. L. Minckley. Pp. 1-18. + June 1, 1960. + + 2. A distributional study of the amphibians of the Isthmus + of Tehuantepec, México. By William E. Duellman. Pp. + 19-72, pls. 1-8, 3 figures in text. August 16, 1960. + + 3. A new subspecies of the slider turtle (Pseudemys + scripta) from Coahuila, México. By John M. Legler. Pp. + 73-84, pls. 9-12, 3 figures in text. August 16, 1960. + + 4. Autecology of the copperhead. By Henry S. Fitch. Pp. + 85-288, pls. 13-20, 26 figures in text. November 30, + 1960. + + 5. Occurrence of the garter snake, Thamnophis sirtalis, in + the great plains and Rocky mountains. By Henry S. Fitch + and T. Paul Maslin. Pp. 289-308, 4 figures in text. + February 10, 1961. + + 6. Fishes of the Wakarusa river in Kansas. By James E. + Deacon and Artie L. Metcalf. Pp. 309-322, 1 figure in + text. February 10, 1961. + + 7. Geographic variation in the North American Cyprinid + fish, Hybopsis gracilis. By Leonard J. Olund and Frank + B. Cross. Pp. 323-348, pls. 21-24, 2 figures in text. + February 10, 1961. + + 8. Descriptions of two species of frogs, genus Ptychohyla; + studies of American Hylid frogs, V. By William E. + Duellman. Pp. 349-357, pl. 25, 2 figures in text. April + 27, 1961. + + 9. Fish populations, following a drought, in the Neosho and + Marais des Cygnes rivers of Kansas. By James Everett + Deacon. Pp. 359-427, pls. 26-30, 3 figures in text. + August 11, 1961. + + 10. North American recent soft-shelled turtles (family + Trionychidae). By Robert G. Webb. Pp. 429-611, pls. + 31-54, 24 figures in text. February 16, 1962. + + Vol. 14. 1. Neotropical bats from western México. By Sydney Anderson. + Pp. 1-8. October 24, 1960. + + 2. Geographic variation in the harvest mouse, + Reithrodontomys megalotis, on the central great plains + and in adjacent regions. By J. Knox Jones, Jr., and B. + Mursaloglu. Pp. 9-27, 1 figure in text. July 24, 1961. + + 3. Mammals of Mesa Verde national park, Colorado. By Sydney + Anderson. Pp. 29-67, pls. 1 and 2, 3 figures in text. + July 24, 1961. + + 4. A new subspecies of the black myotis (bat) from eastern + México. By E. Raymond Hall and Ticul Alvarez. Pp. + 69-72, 1 fig. in text. December 29, 1961. + + 5. North American yellow bats, "Dasypterus," and a list + of the named kinds of the genus Lasiurus Gray. By E. + Raymond Hall and J. Knox Jones, Jr. Pp. 73-98, 4 figs. + in text. December 29, 1961. + + 6. Natural history of the brush mouse (Peromyscus boylii) + in Kansas with description of a new subspecies. By + Charles A. Long. Pp. 99-110, 1 fig. in text. December + 29, 1961. + + 7. Taxonomic status of some mice of the Peromyscus boylii + group in eastern México, with description of a new + subspecies. By Ticul Alvarez. Pp. 111-120, 1 fig. in + text. December 29, 1961. + + More numbers will appear in volume 14. + + Vol. 15. 1. The amphibians and reptiles of Michoacán, México. + By William E. Duellman. Pp. 1-148, pls. 1-6, + 11 figures in text. December 20, 1961. + + 2. Some reptiles and amphibians from Korea. By Robert G. + Webb, J. Knox Jones, Jr., and George W. Byers. Pp. + 149-173. January 31, 1962. + + More numbers will appear in volume 15. + + + + +Transcriber's Notes + +All obvious typographical error were corrected. Due to variant usage +of hyphens, "soft-shelled" and "crystal-clear" were used as the +standard for variants of those terms. All other variant spellings +of "softshell(s)" and where variant spellings occur in quoted text +or literature titles they were retained. Variants in accented +and non-accented words may exist. Paragraphs split by tables or +illustrations were rejoined. + + +Typographical Corrections + + Page Correction + ==== ===================== + 494 Ordinance School Proving Ground => Ordnance + 494 Pl. 12, top => Pl. 42, top + 567 Pl. 52, Fig. 2 => Pl. 51, Fig. 2 + 576 _Agkistrodon piscivorous_ => _piscivorus_ + 595 Carettochlydae => Carettochelyidae + + + + + + + +End of the Project Gutenberg EBook of North American Recent Soft-shelled +Turtles (Family Trionychidae), by Robert G. Webb + +*** END OF THE PROJECT GUTENBERG EBOOK 40005 *** |