10 TEETIAEY VEETEBRATA OE THE EATtTM. 



roughened. The other alveoli are smaller, compressed from before backwards, 

 and crowded together; they are separated by a very small space from the socket 

 of i. 1 in front and by none at all from that of the canine behind. The palatine 

 portion of the premaxillse is small : the premaxillo-maxillary suture runs backwards 

 from immediately behind the alveolus of the last incisor, and the bones form little 

 more of the palate than the high arched roof of the unpaired anterior palatine foramen, 

 the posterior or ventral edge of which is formed by the anterior border of the palatine 

 plates of the maxilla;. The facial portions of the premaxillae form the very narrow 

 vpedge-shaped extremity of the snout, the actual angle of which is somewhat 

 truncated and roughened. The suture with the maxilla (Pis. I., II., III.) runs upwards 

 and backwards to a point midway between the nasal opening and the orbit ; and in 

 front of this the bone unites with the nasal, the suture with which runs just into the 

 narial opening. Within the latter the premaxilla again meets the maxilla, forming a 

 suture with the upward prolongation of that bone, which together with a downgrowtli 

 of the nasal forms a support for the large horns in the manner above described (see the 

 description of the nasals and text-fig. 2). The posterior part of the border of the 

 nasal opening formed by the premaxilla is rounded, but in front of this the bone is 

 bent inwards and downwards and terminates internally in an irregular roughened 

 edge, the posterior angle of which forms a blunt tuberosity. This inturned 

 edge is separated from the corresponding portion of the bone of the opposite 

 side by a deep groove (text-fig. 2, mes.g.), which in life probably lodged the lower 

 edge of a vertical cartilaginous nasal septum. In the young this remains unossified, 

 but in the fully adult animal its anterior region ossifies and forms the prenasal bar 

 of bone joining the nasals with the premaxillse, as above described (see Pis. I., II. 

 fig. 1 a; also text-fig. 2). 



In consequence of the great size and the hypsodonty of the teeth, the maxilla (mx.) 

 is very large. Its facial suture with the premaxilla has already been described, 

 and it will be noticed that it is completely excluded from the margin of the 

 nasal opening by the meeting of the premaxilla and the nasal. Within the 

 nasal opening, however, it is produced upwards into a process which unites 

 with a downgrowth of the nasal in the manner already mentioned. Behind its 

 union with the premaxilla the upper border of the bone meets the frontal, and 

 its suture with that bone terminates just behind the antorbital foramen (a.o.f.), at 

 which point the small lachrymal is interposed, and helps to form the outer 

 side of the bar of bone which closes the antorbital foramen externally. 

 This foramen is very large and opens by a wide passage into the orbit. The 

 maxilla is excluded from the actual margin of the orbit by the junction of the 

 lachrymal with the upper end of the jugal, which sends up a long process 

 forming the whole ventral border of the orbit, and uniting anteriorly with the 

 maxilla. The zygomatic process of the maxilla is very short, extending very little 



