155 



The vertebral scute impressions have the same form and general propor- 

 tions as in Dermatemys. The first is wide, urn-like in outline, and is broader 

 than long. The succeeding three are quadrate, with the length greatly ex- 

 ceeding the breadth, and with the usual lateral brace-like or double-sigmoid 

 borders. The last impression narrows for a short distance and then diverges 

 in the usual manner. 



The costal scute impressions resemble those of emydes and extend further 

 upon the marginal bones than in Dermatemys, nearly reaching the middle of 

 their outer face at the sides of the carapace, as far back as they are preserved 

 in the fossils, as well as in front. 



The position of the nuchal scute is not preserved in the fossils, but the 

 part immediately contiguous in one of them indicates that it had about the 

 same proportions as in Dermatemys. 



The marginal scute impressions about occupied the lower two-thirds of 

 the outer aspect of the marginal plates. The line intervening to the first 

 two marginal scutes is continuous with that between the first vertebral and 

 the succeeding costal scute. 



Considering the striking resemblance of the carapace of Baptemys to that 

 of Dermatemys, it is not a little surprising to observe so much difference in 

 the plastron, though this also is nearly alike in the scute impressions. 



Compared with that of Dermatemys, the plastron is remarkably small, 

 leaving proportionately much larger spaces in advance and behind the bridges 

 for the movements of the animal. As before intimated, it is intermediate in 

 character to that of the last-named genus and that of Staurotypus. The 

 pedicles are intermediate in extent to what they are in the two genera just 

 mentioned. The fore part of the plastron has nearly the same shape as in 

 Dermatemys, but is widely emarginate at the extremity, and it is thick 

 and rounded at the border instead of being acute as usual in emydes. The 

 back part of the plastron is narrower than in Dermatemys, but less so than 

 in Staurotypus. It terminates in a rounded extremity as seen in Fig. 2, 

 Plate XII. In Dermatemys, it ends in a wide notch ; in Staurotypus, in a 

 point. 



The entosternal bone is proportionately as large as in Dermatemys, and has 

 nearly the same form. The same may be said to be the case with the epister- 

 nals, (Fig. 6, Plate XV,) except that their anterior border is more concave. 



