142 



were collected by Dr. Carter in the vicinity of Fort Bridger, and sent to the 

 Smithsonian Institution, whence I obtained them for examination. The 

 specimens consist of portion of a carapace, Fig, 2, and portions of two plas- 

 trons, Figs. 3, 4. Slight difference in the corresponding portion of the latter 

 specimens with that attributed to E. wyomingensis, but especially the absence 

 of any evidence of an intergular scute, led to their being referred to another 

 species. 



The sternal specimen, represented in Fig. 3, accompanied the portion of a 

 carapace, represented in Fig. 2, and from its appearance was assumed to have 

 belonged to the same individual. 



In the sternal specimen just indicated, the entostemal plate is lozenge-shaped 

 in outline, but constricted at the middle of its posterior part. Its length is 

 equal to the breadth, but the evidence from the isolated episternal, first re- 

 ferred to E. wyomingensis, is that its entosternal was wider than long. 



The divisions of the plastron and its impress by scutes, as seen in the more 

 perfect specimen, appear to agree pretty closely with the arrangement ob- 

 served in ordinary living emydes. 



The second sternal specimen, represented in Fig. 4, was supposed to per- 

 tain to the same species as the former one, though exhibiting differences 

 which rather approached it nearer to that first referred to E. wyomingensis, 

 except that it exhibited no trace of the existence of an intergular scute. The 

 entosternal bone is wider than, long, and without conspicuous constriction at 

 its posterior part. The anterior truncated border of the episternum is con- 

 spicuously notched at its outer part. 



In all the sternal specimens indicated, the gular and humeral scutes have 

 doubled over the edge and extended upon the upper surface in the same man- 

 ner as in living emydes. 



In the carapaceal specimen, Fig. 2, the vertebral plates, consisting of the 

 series from the first to the eighth, inclusive, successively decrease in length 

 except that the third is -a little longer than the second, and the fourth and 

 fifth are nearly equal. To the fourth inclusive, the length much exceeds the 

 breadth, but they successively dimmish in this proportion. The fifth is but 

 slightly longer than wide, and the remaining plates are much wider than long. 

 The second and fifth are of the same width, and in this respect exceed the 

 first and intermediate ones, which are likewise of nearly uniform breadth. 

 The sixth plate is the widest of the series; the others successively diminish. 



