524 



GEOLOGY OF THE DENYEE 1JAS1N. 



The Pliocene strata in the plains region, already alluded to, contain 

 a rich series of mammals, among which remains of horses and rhinoce- 

 roses arc especially abundant. The largesl of all these mammals was the 

 Mastodon, the remains of' which occur in place, and also have been found 



tlie left. One-third natural sit 



Fio. 98 skull of /v. tforLi idj Been fir 



in surface deposits at many points. The skeleton of one species oi this 

 genus is restored in PI. XXXI, which will show the form and proportions 

 of this typical proboscidian. 



V'i.;. 99.— I hut. bones and teeth of Pliohippua psrafa Marsh. Pliooene. 

 l'ii. ifii Dhe Bame aeries of Profoftij U ih Pliooene 



Fig. 101. — The same series ol U rMarah. bUooene 



Among the extinct horses of this horizon the genera Pliohippus and 



Protohippus are characteristic, and their remains are almost always to he 

 found 1>\ careful search in any favorable locality. Fie,'s. 99 and 100 

 indicate parts typical of these genera 



