TERTIARY AGE. 



507 



Horse, and probably stood seven or eight feet high. Its remains 

 occur in the lower of the Miocene beds. With it there is a related 

 elephantine horned beast, having a pair of horns, which has been 

 named Brontotherium by Marsh. 



One of the Rhinoceroses (Aceratherium occidentale L.), was about 

 three-fourths as large as the East India species, and another (Byraco- 

 don Nebrascensis L., Fig. 924) half as large. There were also several 



Fiar. 925. 



Oreodon gracilis. 



species of a genus called Oreodon by Leidy, intermediate between the 

 Deer, Camel, and Hog (a skull of one species of which is represented 

 in Fig. 925); and others of related genera. 



Among the Horses, there were species of the genus Anchitherium, 

 mentioned on page 505 ; but no true one-toed Horse (Equus) is known 

 from the beds. 



The Mammals of the Miocene beds on the Atlantic coast, so far as 

 known, are mainly species of Whales, Dolphins, Seals, and Walruses, 

 bones of which have been found on Martha's Vineyard and at other 

 places on the Atlantic coast. Besides these, remains of Rhinoceros, 

 Lophiodon, and Elotherium have been found in New Jersey, and of 

 Camelus in Virginia. 



The Pliocene of South Carolina has afforded the remains of a 

 Mastodon and a Stag (Cervus). In the Upper Missouri region, exists 

 the great cemetery of the Pliocene ; and it is nearly as wonderful as 

 that of, the Miocene Tertiary. From remains gathered first by Hay- 

 den, on the Niobrara, and on the Loup Fork from North Branch to its 

 source, and some other points, Leidy determined and named a large 



