EMYDIDA. 301 
The type specimen was obtained from the Wasatch beds of New Mexico. The more exact 
locality is given as the Gallinas River. 
In his great work on the Vertebrata of the Tertiary Formations of the West, publisht in 
1884, Cope exprest the opinion that his Emys crbollensis may have been founded on a larger 
individual of his Emys euthneta of the “‘red beds” at Black Buttes, Wyoming. To the present 
writer, after comparing Cope’s descriptions and figures and the types of the two forms and after 
study of such materials of E. euthneta as are accessible, Cope’s opinion of 1884 seems erro- 
neous, for reasons to be mentioned below. 
The individual forming Cope’s type was somewhat smaller than the one which formed the 
type of his E. lativertebralis. Its plastron was about 250 mm. long, carapace about 310 mm. 
When Cope described this species he regarded its relationships as being with his Emys lati- 
vertebralis, but he found the peripheral bones of the latter larger and thinner, and both the 
anterior lobe of the plastron and the entoplastron relatively longer. 
Cope figures no costal bones, but he gives the width of one as 22 mm., the thickness as 
6mm. A costal of E. lativertebralis had a width of 24 mm. and a thickness of 5 mm. 
Of the peripheral bones Cope says that they are not, or but little, recurved. He figures 
two of these, but he does not state whether they are anterior or posterior peripherals. Evidently 
both were imperfect. They probably belonged behind, and included the portion between the 
free border and the costo-marginal suture. Cope gives the length of one peripheral as being 
30 mm. and its thickness as g mm.; but the thickness of those fgured must have been about 
12mm. The peripherals of FE. lativertebralis differ in being higher and thinner. On the other 
hand, the posterior peripherals of £. euthneta were more recurved. 
The anterior lobe of the plastron to the hinder border of the entoplastron is 65 mm. long. 
The anterior lip (fig. 379) projected somewhat and is slightly concave in outline. At each side 
is a rather prominent tooth, but there is no cleft separating it 
from the remainder of the lip as there is in E. Jativertebralis. 
The width of the lip, measured to the gulo-humeral sulci, is 
54mm. The thickening on the upper surface of the lip extended 
backward 23 mm. From each lateral tooth there extends back- 
ward a broad ridge. At the hyoepiplastral suture the beveled 
surface is 23 mm. wide. The entoplastron has a length of 36 
Fic. 379.—Echmatemys cibol- ™M., a width of 55 mm., and a thickness of 7 mm. As stated 
lensis. Epiplastral lip of type. by Cope, the bone was transversely diamond-shaped. To the 
x4. No. 2576 U.S. N. M. present writer, the epiplastral lip appears to be quite different 
from that of Emys euthneta. 
The hinder lobe had a total length of g5 mm. and at the rear was a deep notch. There was 
a broad beveled area at the border of the upper surface, and at the hypoxiphiplastral suture 
this was 22 mm. wide. This surface appears to have been strongly imprest by the lines of 
growth of the horny scutes. In Cope’s Emys euthneta this surface was relatively narrow (Vert. 
Tert. Form. West, plate xviii, fig. 42). 
The estimate of the present writer is that the length of the anterior lobe of E. lativertebralis 
equaled 0.75 of the length of the hinder lobe; in £. crhollensis about 0.68. 
The arrangement of the scutes of the anterior lobe of E. crbollensis is quite different from 
that of FE. lativertebralis, since the gulars of the former do not reach backward to the ento- 
plastron and the humerals overlap extensively this bone. The gulars of the present species had 
a length of 25 mm. and, taken together, a width of 54 mm. In E. euthneta the gulars had 
evidently a length fully equal to their combined widths. 
There appears to be no good reason why this species should not be referred to Echmatemys. 
Echmatemys ? megaulax (Cope). 
Plate 45, figs. 14, 15; text-figs. 380-383. 
Emys megaulax, Cope, Sixth Ann. Report U.S. Geol. Surv.Terrs., 1872 (1873), p. 628; Vert. Tert. Form. 
West, 1884, pp. 129, 132, plate xviii, figs. 26-33.—Hay, Bibliog. and Cat. Foss. Vert. N. A., 1902, 
p- 448. : : ; 
Emys pachylomus, Cope, Sixth Ann. Report U.S. Geol. Sury. Terrs., 1872 (1873), p. 629. 
