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