1884.) 533 [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 Jf superbus the former measurement is two and 
one-half times as great as the latter. 
The mandible shows the nearer relationship to the M. macrostegus 
than to the IZ 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 asin M. superbus. It is less con- 
cave in my single specimen than in that of Jf macrostegus. The posi- 
tion of the posterior extremity of the symphysis is below the middle of 
thé 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 ificisive alveo- 
lar border is much more strongly convex than in the MZ 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 pariétosquamosal 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 JZ. 
macrostegus and different from tbat of MM. 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. swperbus and M. macrostegus, 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 
