Douglass — New Species of Herycochoertis in Montana. 79 



MeryeocJimrus compressidens n. sp. 



Represented by a left mandibular ramus extending back to 

 beneath m 3. The premolars and first two molars are nearly 

 perfect. 



The most striking feature of this jaw is the close crowding 

 of the premolars, in all of which there is an overlapping. 



The form of the jaw is most like that of M. proprius. It 

 differs from all those previously described in this paper, in the 

 narrowness of the horizontal ramus, and from at least part of 

 them in the presence of a first incisor. It agrees with these 

 and differs from the M~. superbus type including the so-called 

 M. montanus, M. macrostegus and M. leidyi in the crowding 

 with individual lengthening of the premolars, and the less- 

 relative length of the series as compared with that of the true 

 molars. 



Merycochcerus compressidens n. sp. x -§-. 



As the mandible is quite thick in the region of the chin, the 

 symphysis is broad, especially the lower half. In M. madi- 

 sonius the broadest part is near the top. Back of the chin 

 the ramus is thinner, then it thickens under the last two 

 molars, partly by the bellying inward on the inside, making a 

 large convexity which stops short of the lower border of the 

 jaw. This convexity is bounded infero-posteriorly by the inner 

 fossa. The molar-premolar series is not straight, but somewhat 

 sigmoid, there being a slight curve inward, outward and inward 

 again in passing backward from pm 1. The last two molars 

 form a slight angle with the premolars. 



There is a broad protuberance at the angle of the chin. 

 Back of this, the lower border is nearly straight, as far as pre- 

 served. The mental foramen is small and nearly round. 



