HISTORY OF THE ARTIODACTYLA 



373 



bones of the fore-arm and lower leg remained separate. The 

 teeth were in continuous series, and there was a peculiar feature 

 in the dentition common to nearly every one of the genera. 

 On casual examination, one would say that the animals had 

 four lower incisors on each side and that the lower canine closed 

 behind the upper one, a most exceptional arrangement. More 

 careful study shows that the apparent fourth incisor was the 

 canine, a transformation which has also taken place in all of the 



Fig. 197. — -Head of \Merycochaerus proprius, lower Miocene to lower Pliocene. Re- 

 stored from a skull in the American Museum of Natural History. 



ruminants except the camels, and the tooth which had as- 

 sumed the form and function of the lower canine was really 

 the first lower premolar ; this latter change is not found among 

 the ruminants, but was repeated in a few other extinct famihes. 

 Only two genera of foreodonts {'fMerychyus and -\Mery- 

 cochoerus) survived into the lower Pliocene. Both had the 

 proportions common throughout the family, but \Merychyus 

 was much more slender and lightly built, its lateral digits were 

 reduced in size and very thin and it had hypsodont grinding 

 teeth ; while ^Merycochoerus was of larger size (about that of a 



