222 LAND MAMMALS IN THE WESTERN HEMISPHERE 



totherium) which was distinguished by the simple rings of 

 the tail-sheath. No rodents have yet been found and only 

 a few of the Carnivora, though a large cat, a musteline and 

 a large t"bear-dog" are known. There were no true elephants, 

 but several species of fmastodons, all of which were different 

 from those of the Pleistocene ; and in some, grinding teeth, 

 though still low-crowned, had become much larger and more 

 complex, marking a stage of advance toward the elephan- 

 tine dentition. Horses of primitive type, the feet having 

 three functional toes instead of one, were relatively abundant. 

 Very large llama-like animals were present, but nothing has 

 been ascertained with regard to the deer and antelopes of the 

 time, and the only other representative of the Artiodactyla 

 yet recovered is a peccary, interesting as being a species of the 

 genus {\Platygomis) which became so abundant and wide- 

 spread in the Pleistocene. Scanty and incomplete as this 

 fauna is, it suffices to show that the middle Pliocene mammals 

 were much more primitive than those of the Pleistocene. 



The fauna of the Snake Creek formation in western 

 Nebraska and that of the presumably somewhat later beds 

 of northwestern Nevada, which are referable to the lower 

 Pliocene, may be considered together. The rodents, which 

 are not very fully represented, were quite modern in character 

 and belonged mostly to extinct species of modern genera, 

 such as hares, pocket-gophers, beavers, forerunners of the 

 fGiant Beaver, marmots, sewellels, etc. A remnant of a more 

 ancient world, especially characteristic of the Miocene, is 

 found in the remarkable burrowers, the horned fmylagaulids 

 which have been extinct since the lower Pliocene. Carnivora 

 were abundant, and members of all the families which inhabit 

 North America to-day have been obtained; wolves, f" bear- 

 dogs," t" hyena-dogs" and forms like the Dhole of India were 

 common. The terms f" bear-dogs" and f" hyena-dogs" are 

 not to be understood as implying any relationships of these 

 animals to bears or hyenas, but merely a certain superficial 



