438 Douglass — New Species of Merycochoerus in Montana. 



and the trough-like shape of the maxillo-premaxillaries above ; 

 the crowding together of pms 1 and 2 ; and possibly in the 

 posterior deepening of the mandible. But, as will be seen by 

 comparing the present descriptions with Leidy's figures and 

 descriptions, the face and anterior border are quite different in 

 the two species. In If. rusticus the anterior part of the face as 

 viewed from the side rises more abruptly for a short distance 

 and then more gradually backward. The form of the concavity 

 on the side of the face is different ; the infra-orbital foramen 

 and the anterior inferior root of the zygomatic arch are farther 

 forward ; the latter also is higher as is also the lower border of 

 the malar. The space between the upper canine and first pre- 

 molar is greater and pm 1 does not overlap pm 2. The 

 mental foramen is longer and the chin is less concave, the pro- 

 tuberance at the chin is larger and longer, and the anterior 

 inferior border of the jaw is more nearly straight. M. rusticus 

 is smaller than M. laticeps. 



