246 Mr. C. W. Andrews on the Structure 
reaches a point about 17 centim. from the anterior end of the 
snout and 2 centim. from the middle line, it runs straight 
backwards parallel to the corresponding suture of the opposite 
side to a point considerably behind the external nares, and 
forms the outer limit of the extremely long facial process of 
the premaxilla, which is about 2 centim. wide and with its 
fellow of the opposite side forms a long ridge, convex trans- 
versely, which separates the nasals and extends back to the 
frontals. These latter thrust themselves slightly between the 
premaxille, with which they form an irregular V-shaped 
suture. 
The extension of the premaxille on the palate is very 
small. From the point where the hinder edge of the bone 
crosses the alveolar border it runs backward for about 2centim., 
being here united by suture with the maxilla; it then turns 
forward at a very acute angle, running first forward parallel 
to the axis of the skull, then turning inwards and meeting its 
fellow of the opposite side at a point 6°2 centim. from the 
tip of the snout ; during this part of its course it is in contact 
with the anterior portion of the vomers, which thus thrust 
themselves some distance between the premaxiliz. 
On the inner side of the alveoli, both in the maxilla and 
premaxilla, there is a groove which is only interrupted for a 
short distance at the junction of the two bones. It is at the 
bottom of this groove near its inner border that the tips of 
the replacing teeth make their appearance. In the pre- 
maxillary region the inner border of this depression forms a 
considerable ridge, which stands out some distance beyond 
the level of the intercalated vomers. 
The maailla is a very large bone bearing about twenty- 
eight to thirty teeth. ‘The first and second of these are com- 
paratively small; the next four, which are subequal, are very 
large, the largest in the maxilla. Behind these there is a 
gradual decrease in size to the hinder end of the series. The 
palatal portion of the bone forms only a narrow strip, in which 
lies the groove above mentioned. In front this palatal portion 
of the maxilla unites with the premaxilla for a short distance, 
behind this with the vomer as far as the middle of the 
internal nares, of which it thus forms the outer anterior 
margin. [rom this point it is united with the palatines, and 
posteriorly to these apparently with the transpalatines. 
The facial region of the maxilla is large; as far back as 
the external nares, the outer edge of which it forms, it is 
bounded superiorly by the premaxilla, but behind these 
openings its form and relations cannot be determined in any 
ot the specimens, owing to the crushing they have under- 
