216 GEOLOGY. 



The Bridger beds are most remarkable for the animal remains 

 which they have preserved, and which has made them classic 

 ground for the geologist. From the above description it is seen 

 that they are eminently adapted for the preservation of animal re- 

 mains. At the foot of almost every cliff can be found soine remains 

 of turtles or mammals. 



Animal Life of the Fort B?fdger. — Moluscan life was abundant, 

 but I can only refer to the vertebrate, and especially to the mam- 

 malian life of the time. 



Fishes were represented by numerous forms, among which were 

 species of Phineasler, closely related to the modern catfish, several 

 species of gars and many kinds of mud fish, as Amia. Closely re- 

 lated to the last are numerous species of Pappichthys, some of 

 which are classed by Marsh with Amia. Marsh has also described 

 many species of serpents, one genus of which (Boanus) was allied 

 to our water snakes. The saurians were represented by many spe- 

 cies, which have been mainly described by Leidy and Marsh. The 

 most abundant of these are the crocodiles, of which at least six spe- 

 cies have been defined. Many others, closely related to the croco- 

 diles, are found in the same localities, among which the Glyplo- 

 saurus and Thinosaurus were also described by Marsh. The tur- 

 tles (Chelonid) were also present in large numbers. Species of the 

 genus Emys were most abundant, though there were also many of 

 the soft shelled kind (Trionyx), and of several other genera. Some 

 of them were small, but many of them were of gigantic size. Some 

 of the land turtles of the genus Hadrianus, described by Cope, were 

 from twenty-five to twenty-nine inches in length, and proportion- 

 ately broad. They were probably the largest of all the extinct 

 land tortoises. 



True, birds seem to have been abundant. One of the first de- 

 scribed from this group was a form allied to an owl, and called by 

 Marsh Bubo leptosteus. One genus of waders (Alletornis), was 

 represented by five species. The remains of a woodpecker (Uiniot- 

 nis leucaris), have also been described by Marsh. 



The highly generalized Tillodontia, that appeared already in the 

 Vermillion group, were here represented by several genera. Of 

 these, species of Tellotherium were the most abundant. With these 

 fossils are mingled many species of rodents. 



The hoofed odd-toed {Ungulatd) animals were present in great num- 

 bers. One of these genera, of which several species have beende- 



