576 THE BEIDGER EPOCH. 



The narrowness of the cranium is readily seen on comparing the post- 

 glenoid processes. These are strong, and have considerable transverse 

 extent, and are separated by a space only a little greater than the trans- 

 verse diameter of each. A strong groove passes along the inner base of the 

 postglenoid process to the foramen lacerum. It is overhung by a promi- 

 nent horizontal ridge of the postglenoid. The zygomatic arches are com- 

 pressed posteriorly, with crest-like superior ridge, but rounded above ante- 

 riorly. There is not the least trace of posterior boundary of the orbit. The 

 squamosal process overlaps the malar bone extensively, terminating in a 

 point, which ends obtusely. The malar is supported in front by a maxillary 

 process, which is united with it by a zigzag suture on the outer face, and a 

 squamosal one within and below. The foramen infraorhitale exterius is large, 

 and issues a short distance in front of the orbit, not so near it as in the 

 elephants. From this point to the ridge inclosing the canine alveolus the 

 side of the maxillary bone is deeply concave, and the palatal surface con-e- 

 spondingly contracted. The bone is continued upward and outward as the 

 external part and apex of the middle horn-cores. Anteriorly it is bounded 

 by the premaxillary to a point as far anterior to the base of the horn as the 

 width of the latter; behind that point it is in contact with the nasals. The 

 premaxillary is prolonged upward and backward into a narrow tongue. Its 

 inferior portion is convex above on each side, concave below, with project- 

 ing alveolar borders, which are flat and slightly concave fore and aft. The 

 extremity of each is rugose below, supports a prominent tubercle medially 

 and a smaller one at the superior angle. 



The exterior nares are not separated by osseous septum. Their lateral 

 border is marked on the inferior surface of the nasal and pi-emaxillary 

 roof by a curved ridge or crest, which converges forward and bounds the 

 interior concavity of the roof. This gave support to muscular or ligamen- 

 tous attachments. The posterior angle of the nares is abruptly excavated, 

 and with thickened walls. The palate is remarkably narrow, and is most 

 deeply excavated between the alveoli of the tusks, or at the maxillo-pre- 

 maxillary suture. From near this point to the palatine suture a low but 

 sharp crest extends along the middle line. The width of the palate at the 

 diastema is one-ninth of its length. The diastema is more than half the 



