518 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 48. 



The pterygoid processes of the alisphenoid have the appearance of 

 having been quite different from those of both the existing bison and 

 the jersey cow. In both the latter animals these processes extend 

 far downward and forward from their bases, 45 mm. in the jersey, 

 60 mm. in the small cow buffalo mentioned above. In this latter 

 specimen each process has, very close to its distal end, a width of 21 

 mm. In our fossil species these processes appear to have been only 

 about 20 mm. long, in this respect resembling some of the antelopes; 

 and they come to a point in front. It is possible that a thin edge has 

 disappeared, but there is no evidence of it. On the inner face of the 

 front edge there appears to be .a sutural surface for union with the 

 palatine and the pterygoid. This front edge slopes directly down- 

 ward and meets the descending hinder border, so that the process is 

 triangular. The base of the process is about 18 mm. long. The hin- 

 der border is acute; while in both the jersey and the American bison 

 it is thick and obtuse. 



The region at the inner extremity of the petrous bone and in front 

 of it appears to have been extremely different from that usually seen 

 in artiodactyls. In the jersey and the existing bison and nearly 

 all other artiodactyls the foramen ovale is inclosed by the alisphenoid. 

 While the bar of the bone on the outer, border of the foramen in the 

 bison is narrow, it is thick, 5 mm. or more, on the inside nearly 

 10 mm. In the jersey, too, the bone is thick all around the opening. 

 In both these animals the foramen lacerum medius is cut off from 

 the ovale by a wide stretch of bone belonging to the alisphenoid. 

 On the other hand, in the fossil here described the region in front 

 of the petrosal is widely open; and, apparently, the two foramina 

 mentioned formed one. The alisphenoid certainly appears not to 

 have sent a prong of bone around the outer side of the foramen 

 ovale. The bone forming the front boundary of this foramen comes 

 down to a thin acute edge, and when it is followed around to meet the 

 squamosal the alisphenoid appears to have stopped there. The 

 opening which represents the two foramina mentioned extends back- 

 ward 27 mm. to the bone. Backward it widens to nearly 25 mm. The 

 hinder part of this gap was, of course, occupied by a part of the 

 bulla. It is possible that the outer edge of the basisphenoid ex- 

 tended into the opening and restricted it somewhat, but there is 

 little or no evidence of it. It is more likely that the inner border 

 of the squamosal extended inward farther and narrowed the foramen 

 somewhat. In the antelope Taurotragus the foramen ovale is some- 

 times large and the alisphenoid bar on its outer border is inter- 

 rupted, but always this foramen is closed behind by a union of the 

 alisphenoid with the squamosal. 



After renewed examinations of this region in the fossil and com- 

 parisons of it with specimens of Bison bison the author fails to 

 find any way of reconciling the differences. 



