P^RT SECOIS'D. 



THE WHITE RIVER AND JOHN DAY FAUN^. 



REPTILIA. 



No vertebrata of a rank inferior to the reptiles have yet been found in 

 the Lacustrine Tertiarj- formations of the central part of North America, 

 which lies between the Upper Eocene and Loup Fork horizons. Neverthe- 

 less, as fishes are known from the Bridger, Amyzon, and Loup Fork beds, 

 and Batrachia have been obtained from the Green River and the Loup 

 Fork, it is probable that they existed in the West during the intervening- 

 time. 



The Beptilia are represented by a good many species and a moderate 

 number of individuals, but were much less numerous than during the epochs 

 of the Eocene. The order of Crocodilla apparently became extinct; a small 

 remnant of the tortoises only continued, and the number of species of liz- 

 ards greatly diminished. The Ophidia only, retained their position, if we 

 can judge by the moderate number of species discovered so far in the two 

 formations. As to their characteristics, the Reptilia of the Miocene beds 

 resemble those of the recent period much more closely than do those of the 

 Eocene. All of the peculiar types of tha^ period had disappeared, and those 

 which came upon the scene can nearly all be arranged in existing families, 

 and in one instance (I'estudo), in a recent genus. The numerical and hori- 

 zontal relations of these forms may be represented as follows : 



Number of species. 



White River. Jobu Day. 



Crocodilla 



Testudinata 4 1 



Laeertilia 8 1 



Oljbidia 4 1 



761 



