Anterior lobe of plastron < . P^, ' " 



TESTUDINATA. 137 



M. 



106 



axilla 144 



Length of bridge 144 



Posterior lobe of plastron J . ". . i 'ili^ ,a^ 



Width of anterior lip 0(58 



There is a peculiarity in the form of the lip of the plastron of the 

 specimen on which this species rests, which may be a specific character. 

 Instead of having an abrupt lateral prominence and truncate or concave 

 anterior border, its outline is regularly convex, onl)- interrupted by the 

 notch, which is half way between the median and lateral gular sutures. 



I dedicate this species to my friend Arthur O'Shaughnessy, of the 

 British* Museum, who has published a number of important papers on her- 

 petological subjects. 



The specimen above described was found by myself on Cottonwood 

 Creek, near Fort Bridger, Wyoming. 



Emys haydeni Leidy. 



Proceedings of the Philadelphia Academy, 1870, p. 123. Annual Report U. S. Geol. Surv. Terrs., 1871, 

 p. see. JS. loyomingenBU Leidy, part Report U. S. Geol. Surv. Terrs., Hayden, i, p. 14, PI. ix, fig. 6. 



The central parts of the carapace and plastron of an Emys from Cotton- 

 wood Creek, Wyoming, belong to a species distinct from the E. wyomingensis, 

 as it appears to me, and agrees very nearly with the figure and description 

 of the specimen on which Dr. Leidy established his E. liaydeni. In fact, 

 the general appearance of the specimen is that of a Baena, a resemblance 

 produced by the density of the tissue and general coossification of the parts 

 as well as the fineness of the sutures where apparent. 



The species differs from the E. wyomingensis in the marked and regular 

 convexity of the carapace, both longitudinally and transversely, resembling 

 no little a portion of the shell of an egg. The dermal sutures are straighter 

 and less undulating on the carapace. The vertebral scuta are relatively 

 longer, and their borders are not bracket-shaped laterally, and are very little 

 or not angulate before and behind. On the other hand the grooves of the 

 plastron are irregular, crossing and recrossing the median line at various 

 points. The humero-pectoral suture crosses the mesosternum well in ad- 

 vance of its posterior border. 



