362 E~. L. Troxell — Entelodonts in Marsh Collection. 



"Elotherium clavum, sp. nov. 

 ' ' On Plate IX, figure 1, is shown a skull of Elotherium, with 

 the brain-cast in position, which agrees in many respects with the 

 skull figured on the preceding plate, and described above (E. 

 crassum ) . When first figured, the former skull was referred to 

 E. crassum (Dinocerata, p. 65, 1884), but a more careful com- 

 parison proves it to be distinct. It is considerably smaller than 

 E. crassum, and the malar process is quite slender and tapering 

 below. It extends directly downward, and hence is not seen in 

 the top view of the skull. The length of this skull is sixteen 

 inches, measured from the front of the premaxillaries to the back 

 of the occipital condyles. The dentition agrees, in the main, with 

 that of E. crassum, the last lower molar in each having four cones 

 only, and no heel. The malar arch and the dependent angle of 

 the lower jaw will distinguish it from E. mortoni. The type 



Fig. 1. — Archceotherium clavus clavus (Marsh). Holotype. Cat. No. 

 12035. Side view of skull and jaws. One-fifth nat. size. 



specimen here figured is from the Oreodon beds, near the White 

 river, in southern Dakota." 



Two points are offered in contradiction to the descrip- 

 tion above, viz : there is a definite heel on M 3 and the de- 

 pendent processes from the malar do swing outward. In 

 1909 Peterson made this a subspecies under A. mortoni 

 Leidy, but here it is raised again to the rank of a full spe- 

 cies on the basis of the description which follows : 



In this species (figs. 1-3), the skull is slender and the 

 framework of the zygomatic arch is light, this being in 

 harmony with the longer, more slender canines. The de- 

 pendent process from the jugal is very narrow ; it seems 

 to point neither forward nor backward, but is of course 

 swung outward ; its anterior edge is in line with the mid- 

 dle of the orbit. The posterior process has a notch to 

 receive the end of the temporal bone, and in this species 



