250 LAND MAMMALS IN THE WESTERN HEMISPHERE 



of artiodactyls and perissodactyls. The latter had suffered 

 serious losses as compared with the preceding or White River 

 stage. Up to and through White River times the perisso- 

 dactyls had held their own in actual diversity, though the 

 rise of the artiodactyls had put an end to the dominant position 

 which they had maintained in the Eocene. With the John 

 Day the actual decline may be said to have begun. The 

 rhinoceroses were represented chiefly by the fdiceratheres, 

 with a transverse pair of horns, some species of which were much 

 larger than those of the lower Miocene. Hornless rhinoceroses 

 have not yet been certainly found, though there is every rea- 

 son to believe that they then existed, as they unquestionably 

 did both before and after. Tapirs occurred but rarely and 

 the horses were individually abundant, though in no great 

 diversity ; they were smaller and lighter than the horses of 

 the lower Miocene. Enough has been found to demonstrate 

 the presence of the clawed fchalicotheres, but not to show how 

 they differed from their immediate successors. 



In the number of individuals, species, genera and famiUes, 

 the artiodactyls of the John Day much exceeded the perisso- 

 dactyls. The peccaries were numerous, but smaller and more 

 primitive than those of the succeeding age, as were also the 

 tgiant pigs, or fentelodonts, but the latter were very large. 

 The peculiarly North American family of the foreodonts was 

 very numerously represented, and one genus {fPromeryco- 

 choerus), comprising animals not unUke the Wild Boar in size 

 and shape, was the probable beginning of the series of proboscis- 

 bearing foreodonts, which led to such grotesque forms in the 

 middle and upper Miocene. A family closely alUed to the 

 foreodonts, and by many writers included in the latter, is the 

 very remarkable group of the f Agriochoeridse, which was dis- 

 tinguished by the long, stout and cat-like tail and by the 

 possession of claws instead of hoofs. The family is not known 

 to have existed later than the John Day and no trace of it 

 has been found in the succeeding formations. The camels 



