374 LAND MAMMALS IN THE WESTERN HEMISPHERE 



large domestic pig) and stouter build and had low-crowned 

 teeth; its head, however, had a very different appearance, 

 given by the possession of a short proboscis, the presence of 

 which is indicated by the greatly reduced nasal bones; the 

 jaws and face were also much shortened. The eye-sockets 

 presented obliquely forward and upward, intead of laterally, 

 as is usual among mammals, and were placed high in the head. 

 This position of the eyes and of the entrance to the ear renders 

 it probable that ^Merycochaerus was largely aquatic in its habits. 

 Both genera had short, four-toed feet, as was general through- 

 out the family and in no genus did the reduction of digits proceed 

 beyond the loss of the first of the original five, the poUex and 

 hallux. 



The two genera above described, representatives of two 

 distinct phyla within the family, held over, as it were, from the 

 upper Miocene without essential change. The phylum of the 

 hypsodont and slender fMerychyus went back, with only minor 

 modifications, into the upper substage of the lower Miocene, 

 but cannot as yet be traced to an Oligocene ancestry ; it is 

 therefore still impossible to say just where and when it branched 

 off from the main stem of the family. Future discoveries in 

 the Oligocene will no doubt clear up this problem. The real 

 terminal and most highly specialized member of the ]Mery- 

 cochoerus phylum and the most extraordinary member of the 

 entire family was confined to the upper Miocene. The extreme 

 peculiarity of this genus {^Pronomotherium) was displayed only 

 in the head, which was an exaggeration of the ^Meryco- 

 choerus type, the face being excessively shortened and the nasals 

 so reduced as to show that the proboscis was much better 

 developed than in the parent genus. The shortening of the face 

 and the great vertical height of the skull and lower jaw gave 

 a decided likeness to the skull of a great ape, though the probos- 

 cis would mask any such resemblance in the living head. 

 fMerycochcerus itself went back to the upper division of the 

 lower Miocene, but in the lower division it was replaced by an 



