1884.] QOO [Cope. 



great prolongation of the palatal floor of the nareal cavities. The distance 

 from the foramen magnum to the nareal border equals the distance from 

 the latter to the line connecting the median external vertical crests of the 

 last superior molars. In M. superbus the former measurement is two and 

 one-half times as great as the latter. 



The mandible shows the nearer relationship to the M. maerostegus 

 than to the M. superbus, in the anterior elongation and greater relative size 

 of the premolar teeth. It agrees with the former in having the profile of 

 the symphysis concave, and not convex as in M. superbus. It is less con- 

 cave in my single specimen than in that of M. maerostegus. The posi- 

 tion of the posterior extremity of the symphysis is below the middle of 

 the third inferior premolar. The coronoid process is low, and of small 

 size. Its compressed convex apex is directed at an angle of 45° from the 

 middle line outwards and forwards. Its anterior face soon widens out 

 and the internal edge becomes much more prominent than the external, 

 with which it encloses a shallow, subtriangular, subvertical fossa. The 

 external border is continuous with the external alveolar border. The 

 masseteric fossa is small and has no distinct inferior border, and does not 

 descend below the level of the line of the middle molar teeth. The in- 

 ferior border of the ramus is nearly straight. The inferior incisive alveo- 

 lar border is much more strongly convex than in the M. superbus. The 

 condyle has the posterior articular face on the inner side, as in other 

 species. 



The infraorbital foramen is large and is above the anterior part of the 

 first true molar tooth. The meatus auditorius is small. There are two 

 postparietal foramina on the parietosquamosal suture. No supraglenoid 

 or postglenoid foramina. There are two mental foramina, one not small 

 below the anterior part of the first true molar, the other, quite large, 

 below the posterior part of the third premolar. The dental foramen is 

 situated on a level with the alveolar border and well posteriorly, its ante- 

 rior border being a little in front of a line dropped vertically from the 

 apex of the coronoid process. It is thus similar in position to that of M. 

 maerostegus and different from that of M. superbus, where it is above 

 the line of the apices of the molars, and is posterior to the line dropped 

 from the apex of the coronoid. 



In the superior true molars, the size increases rapidly posteriorly. The 

 third is relatively of more elongate form than the first, but the posterior 

 external column is but little produced. The other vertical ridges are 

 quite prominent. The external faces of the external lobes are nearly flat. 

 Besides the relation of the adjacent horns of the internal crescents already 

 mentioned, the posterior horn of the posterior crescent in the first and 

 second molars is cut off from the external wall of its own crown by the 

 anterior horn of the anterior crescent of the crown next posterior. This 

 does not exist in worn molars of M. superbus and M. maerostegus, but 

 is observable in little worn teeth of the former. It does not look as though 

 the character would disappear with wear in the M. montanus. The only 



