HISTORY OF THE CARNIVORA 



549 



and functional digits, armed with very long, sharp and non- 

 retractile claws. 



The Pleistocene representatives of the family in America 

 included species of the true bears ( Ursus) and of the very large 

 fshort-faced bears {] Arctotherium) which ranged over both 

 North and South America. In ] Arctotherium the dentition 



Fig. 275. — Restored head of the fShort-faccd Bear {] Arctotherium bonoeerense). From 

 a skull ia the National Museum, Buenos Aires. 



was less modified ; the larger premolars were very closely 

 crowded together and the molars were nearly square ; the lower 

 jaw was almost as much curved as in the raccoons. The 

 humerus retained the epicondylar foramen. The family, 

 which was of Old World origin, may have reached America 

 in the lower Pliocene, but was rare until the late Pleistocene. 

 '\Arctotherium has not been found in the eastern hemisphere, 

 but that, of course, is no proof that the genus was not an im- 



