234 THE SKULL. [CHAP. 



is dilated with air sinuses. There is a small postorbital 

 process. The lacrymal is very small, and the canal is 

 external to the margin of the orbit. The malar is attached 

 to the frontal, lacrymal and maxilla in front, curves down- 

 wards and outwards, and then divides into a descending and 

 a high ascending branch ; but neither of them join the 

 straight zygomatic process of the squamosal. The nasals are 

 short and wide. The anterior nares are nearly vertical, or 

 rather inclining downwards. The premaxil!ae are exceedingly 

 rudimentary, only the palatal portion being present, without 

 any ascending process ; they unite with each other across 

 the middle line, but not with the maxillae, hence they are 

 generally lost in macerated skulls. The palate is narrow, 

 especially posteriorly, and not produced behind the molar 

 teeth. The pterygoids form large plates with prominent 

 rounded borders, compressed in some, and inflated in 

 other species. The glenoid fossa is narrow from side to side. 

 The tympanic, squamosal, and periotic are ankylosed 

 together. The former forms a considerable bulla, but no 

 tubular meatus. There are large supratympanic air sinuses, 

 and a well-marked ossified tympanohyal. 



The mandible has a comparatively high horizontal por- 

 tion, rounded in front with a very small median triangular 

 process at the upper border. The coronoid process is high 

 and slender. The condyle is small ; its articular surface 

 is convex from side to side, short and nearly straight 

 from before backwards. The angle forms a broad com- 

 pressed posterior projection, with a slightly incurved lower 

 border. 



The stylohyals are large, compressed, and curved, with a 

 prominent posterior process near their upper end. The 

 basihyal is small, and ankylosed with the thyrohyals, so that 

 they form together a V-shaped bone. 



