CENOZOIC ERA. AGE OF MAMMALS. 379 



Pliocene. Here, again, we have a great change of 

 mammalian species. The animals are much more like 

 existing species. If many existing families commenced 



FIG. 341. Brontops. (After Marsh.) 



in the Miocene, we find many existing genera, such as the 

 horse (equus), the camel (camelus), the elephant (elephas), 

 etc., commencing in the Pliocene. Great numbers of the 

 horse family, Protohippus, Plichippus, and finally Equus, 

 great numbers of the camel family, several elephants and 

 mastodons, roamed in herds over the American Continent. 

 The Protohippus was a three-toed horse, like the Miohip- 

 pus, but the side-toes were shorter. It was very similar 

 to the Hipparion of Europe (Fig. 343). The Pliohippus 

 was very horselike. It was one-toed., like a true horse, 

 the two side-toes having dwindled to splints. 



Foreign Localities. 



Paris Basin. Among foreign Tertiary deposits the 

 most celebrated is the Eocene basin of Paris. The streets 

 of Paris teem with a living generation of men and animals. 



