Chapter II: Part 2

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.

_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_.

_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.

_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).

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.

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).

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).

_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).