24 



or iVagments tbiiiul together belonged to tlie same .skeleton, and in must 

 instances they have appeared to belong to several ditierent animals. 



The remains of vertel)rates thus far discovered in the Bridger Tertiary 

 formation represent all classes except Batrachians, and these no doubt 

 formed members of the ancient fliuna : but their delicate bones have, as yet, 

 escaped detection. 



The remains of mammals are especially numerous, and they belong to 

 many genera, most of which are extinct, and had not been previously 

 described or tbund elsewhere. The greater proportion of the mammals were 

 odd-toed pachyderms, whose nearest living allies are the tapirs. Proboscidian 

 and equine forms appear to have been sparsely represented. Even-toed 

 pachyderms were comparatively few ; and ruminants, whose remains are so 

 abundant and varicil in the later Tertiary formations east of the Rocky 

 Mountains, appear to have been absent. The other remains of mammals 

 belong to rodents, insectivores, and carnivores, nearly all of extinct genera, 

 not previously described nor found in other localities. Primates, bats, mar- 

 supials, and edentates are probably represented, but have not been certainly 

 recognized among the fossils which I have had the opportunity of examining. 

 The nature of the formation from which the remains are obtained is such 

 that we do not expect to find evidences of the remaining orders of mammals. 



No remains of birds have come under my notice; but Professor Marsh, 

 who has explored the Bridger Tertiary beds with unusual facilities and great 

 diligence, has reported the discovery of specimens which he attributes to half 

 a dozen species of two extinct and previously unknown genera.* 



Of reptiles, the remains of turtles are, perhaps, the most abundant fossils 

 met with in the buttes of the Bridger basin. They belong to a number of 

 different genera, several of which are extinct, but others belong to genera 

 still in existence. Most of them are aquatic forms, but one at least was a 

 land-tortoise. The number of species and genera is in striking contrast with 

 the single species, represented by a multitude of individuals in the Tertiary 

 deposits of White River, Dakota, and of Niobrara River, Nebraska. 



The turtle remains mostly consist of the shells, often nearly complete, 

 and sometimes including other bones ot^ the skeleton imbedded in the interior 

 matrix. 



The remains of crocodiles, which are entirely wanting in the White 



* Am. Jour. Sc, 1872, p. 25G, 



