E. L. Troxell — Entelodonts in Marsh Collection. 251 



these is a very long process descending from the malar 

 bone and giving attachment to the masseter muscle." 

 This was the first report of this very odd character in one 

 of the entelodonts. On a later page in this paper the type 

 is figured and the description amplified in the hope that 

 we may find material comparable to it. It should be care- 

 fully noted that most of the description of this species 

 by Marsh ? Peterson, and others has been made from an 

 apotype, 3 specimen No. 12025 (see PL III, A), which is 

 found in many respects to be different from the original 

 and is here made the type of a new species, A. marshi. 



Archceotherium clavus (Marsh) was considered by 

 Peterson to be a subspecies of A. mortoni, but due to the 

 fact that the skull has now been completely freed from the 

 matrix, showing the teeth and other parts (figs. 1-3), here- 

 tofore unknown features will be pointed out which it is 

 believed will reinstate the name as that of a full and sep- 

 arate species. The holotype is Cat. No. 12035 of the Yale 

 collection. 



Pelonax ramosus Cope is a genus and species made on 

 the great size of the tubercles on the lower jaw and on the 

 single-rooted premolars, I and II. It is based on the 

 ramus of a mandible of a very large animal of which the 

 skuir, according to Cope, would have measured nearly 2y 2 

 feet in length. 



Pelonax potens (Marsh) Peterson (figs. 13, 14) is a pe- 

 culiar species, with very heavy mental tubercles, single- 

 rooted first premolar, and, unlike the type of the genus, 

 with a double-rooted, though small, second premolar. 

 The type specimen consists of the lower jaws with the 

 fourth premolar and the three molars of one side. It is 

 No. 12042 of the Yale Museum collection. 



Pelonax batlirodon (Marsh) Peterson (PL III, B), has 

 for its type a single lower third molar which, roughly esti- 

 mated from the dimensions given by Cope in his original 

 description, is about 3 mm. less in length than the cor- 

 responding tooth of P. ramosus. The specimen is indis- 

 tinguishable from Cope's description of P. ramosus and is 

 inadequate as a type. It is Cat. No. 12030 of the Yale 

 collection. 



Dceodon^shoshonensis Cope is known by the body of the 

 ramus of a very large animal. The extreme width and 



3 See Schuchert, C., and Buckman, S. S., Science, n. s., 21, 899, 1905. 



