GEOLOGICAL SUEVEY OF THE TEERITOEIES. dbl 



BAPTEMYS. 



An extinct genus of terrapenes, thus named, is established on an 

 almost perfect shell, obtained from the miocene tertiary deposits in the 

 vicinity of Fort Bridger, Wyoming. It was submitted to our examina- 

 tion by Mr. O. 0. Smith of Amherst, Massachusetts. The genus ap- 

 proaches in character the existing Dermatemys of Central America. 

 The pedicles of the sternum are covered by a large scute intervening 

 between the comparatively large inguinal and axillary scutes, and sep- 

 arating the humeral and abdominal scutes from the marginal ones. 



Baptemys wyomingensis. — The shell of the species measured about one 

 foot and a half in length by a foot in breadth. 



BJENA. 



Another extinct genus of turtles is indicated by two nearly complete 

 shells, obtained from the tertiary formation near Fort Bridger, Wyoming. 

 One of the specimens was discovered during Professor Hoyden's last ex- 

 pedition ; the other was presented to the writer by Dr. J. Van A. Carter, 

 of Fort Bridger. The genus partakes of characters of the terrapenes 

 and the snappers. The shell is moderately convex as in the latter, and 

 like it is notched at the slides posteriorly. The sternum is more like 

 that of the emydes than of the snappers. The sternal pedicles are deep 

 and wide, and are impressed by one or two large scales intervening be- 

 tween the humeral and abdominal and the marginal scutes, and sepa- 

 rating comparatively large axillary and inguinal scutes. 



Bcena arenosa. — In its perfect condition the shell measured about four- 

 teen inches long and about ten and a half wide. Two large scutes inter- 

 vene to the axillary and inguinal scutes. 



Bcena affinis. — This may, perhaps, be the same as the former. It was 

 nearly of the same size and shape, but in the specimen which has sug- 

 gested the idea of a species distinct from the former, a single accessory 

 scute intervenes to the axillary and inguinal scutes. 



TRIONYX. 



The genus of soft-shelled turtles is represented by a number of extinct 

 species belonging to both the secondary and tertiary formations of this 

 country. Numerous fragments, in the collections of fossils obtained by 

 Dr. J. Van A. Carter, and in those made during Professor Hayden's last 

 two expeditions, from the tertiary deposits of Wyoming, apparently indi- 

 cate two extinct species. Only one of these, however, can be charac- 

 terized from the more perfect of the specimens. 



Trionyx guttatus. — This species is established on a large portion of a 

 carapace, discovered by Professor Hayden in 1868, at Church Buttes, 

 near Fort Bridger, Wyoming. The shell of the animal was about a foot 

 and a quarter long by a foot in breadth. 



CEOCODILIA. 



Bemains of crocodilians have not been found so abundantly in the 

 West as might have been supposed. None have thus far been found 

 among the multitude of other reptilian remains in the cretaceous form- 

 ations of Kansas and Dakota. None have been discovered in the 

 miocene tertiary deposits of the mauvaises terres of Dakota, nor the 

 pliocene sands of the Niobrara Biver. One would have suspected that 

 crocodiles would have been abundant where there were such vast num- 

 bers of mammals feeding in the vicinity of streams and lakes of fresh 



