DERMATEMYDID&. 271 
Batrach. Reptilia, Aves N. A., 1869 (1870), p. ii Hay » Bibliog. and Cat. Foss. Vert. N.A., 1902, 
p- 445; Amer. Jour. Sci. (4), XVII, 1904, p. 265, plate xiii, Ags. 1-3, text-fig. 2; Amer. Geologist, 
XXXV, 1905, Pp. 331 
Adocus vyomingensts, Core, Ext. Batrach., Reptilia, Aves N. A., 1870, p. 233; Proc. Amer. Philos. Soc., 
XI, 1870, p. 297. 
ernciergs wyomingensis, Cope, 6th Ann. Report U.S. Geol. Sury. Terrs., 1872 (1873), p. 624; Amer. 
Naturalist, xv1, 1882, p. gt, fig. 9. 
Dermatemys vyomingensts, CoPE, Vert Tert. Form. West, 1884, p. 142. 
Baéna ponderosa, Corr, 6th ‘Annt Report U.S. Geol. Surv. Terrs, 1872 (1873), p. 624. 
Baéna? ponderosa, Hay, Bibliog. and Cat. Foss. Vert. N. A., 1903, p- 438. 
The type of the present species belongs to the Academy of Natural Sciences at Phila- 
delphia. The specimen was obtained somewhere in the neighborhood of Fort Bridger, 
Wyoming, from which locality probably all the known specimens have been derived. The 
level is therefore that of the lower portions of the Bridger beds. Of the type, some of the 
peripherals are missing, also the front of the plastron. "The total length of the carapace in 
life was nearly 450 mm.; the breadth, about 310 mm. On the hinder third of the carapace 
there is a prominent carina, the summit of which is flat. The anterior neurals are considerably 
longer than wide, with the broader end directed forward. The free borders of the anterior 
peripherals are thickened and obtuse. The surface of the carapace is mostly smooth, but pos- 
teriorly somewhat corrugated. The dimensions of the vertebral scutes are given in the table. 
The plastron is relay ely small, and 
eee Mealectwaad VERA large spaces are left between it and the 
type. A.M.N.H. 1494: A.M.N.H. carapace, thus favoring the movements 
a S ~ of the legs. The anterior lobe is 148 
| No. Length.Width. No. Length. Width. No. Length. Width. mm. wide at the base. The bridge has a 
se ail" a width of 105 mm. The hinder lobe ter- 
| minates obtusely behind. The length is 
| 104 62 
jy a 81 108 I 50 22 I 68 go 
| 2 2 2 | 22 2 85 33 94mm.; the width at the base, 115 mm. 
3 9° 68 2 45 21 3 83 55 On each of the bridges are 3 inframar- 
4 79 66 4 40 22 4 86 60 : : 
| 5 ie 5 : 23 H 110 ~—10_:~«|s gall scutes. Of these the hindermost 
6 37 28 extends forward on the hyoplastron. 
i ie Dr. Leidy described a second spec- 
; imen which had been discovered at 
- Church Buttes. This shell was impor- 
tant because it furnisht the front of the plastron, which Leidy figured in his Contributions 
(plate xv, fig. 6). This front, however, differs so much from that of all others found since, 
that there is some reason for suspecting that it belongs to a distinct species, being truncated 
and notcht in front. Below some details are given regarding this specimen. 
In the Cope collection belonging to the Mince Museum of Natural History is a large 
specimen which presents the carapace (plate 40, fig. 1; text-fig. 337); but of the plastron there 
is only the impression of the hinder lobe on the matrix. The catalog number is 1494. Were 
it not that Cope describes the form of the anterior lobe, it might be supposed that it 1s the 
specimen mentioned by him in the Proceedings of the American Philosophical Society (vol. 
Xi, p- 297). Lt is possible that that author did not intend to state that his specimen possest 
this lobe, but referred to what Dr. Leidy had determined. The total length of the carapace is 
435 mm., in a straight line; the width is 283 mm.; and the height, about 180 mm. The 
specimen is remarkable for its narrowness. The anterior edge is thickened and rounded like 
the edge of one’s little finger. The thickness of the first peripheral is 16 mm. The hinder 
free borders are also obtuse, but much thinner, the thickness near the edge of the tenth being 
7mm.; but this increases to 14 mm. at half the height of the bone. The neurals are narrow. 
The dimensions of the neurals and the vertebral scutes are presented in the table above. 
There are 12 pairs of marginal scutes. The costo-marginal sulcus runs considerably below 
227 
the oe -peripheral suture. There appears to be present a ninth pair of costal plates (fg. 337, 
z Pf 9): - . - 1 
The American Museum expedition of 1903 secured 2 specimens of this species at Grizzly 
Buttes. These have the catalog numbers 5934 and 5967. No. 5967 presents a large portion 
