1 82 THE SKULL. [chai\ 



being nearly horizontal. The ridge which separates the 

 anterior from the posterior division of the cerebral fossa is 

 very well marked. The pituitary fossa is very shallow, and 

 there are no distinct clinoid processes. The supraoccipital 

 (SO) is high, and inclines greatly forwards; so that the occi- 

 pital surface looks upwards as much as backwards. In the 

 adult skull (Fig. 60) the lateral parts of the occipital region 

 (rounded smoothly off in the young state) are vastly expanded 

 and leave between them a deep median depression, with a 

 rugged floor, and a partial bony septum at the bottom, into 

 which the ligamentum nuchae is inserted. The median por- 

 tion of the supraoccipital never becomes expanded by air- 

 cells. The parietals (Pa) are very large, and form the greater 

 part of the lateral walls of the cranium. The frontals (Fr) 

 are narrow from before backwards, and produced laterally 

 into elongate supraorbital processes, which send out small 

 postorbital processes, not, however, completely separating 

 the small orbit from the large and high temporal fossa. 



The most remarkable feature in the face is the form and 

 position of the anterior narial orifice (an). It is wide trans- 

 versely, very short from above downwards, placed very high, 

 and is directed upwards and forwards, almost as much as in 

 the Whalebone Whales. The nasal bones (No) which bound 

 it above are very thick, short, broad behind, and conical 

 in front, and contain large air-cavities. The inferior and 

 lateral margins of the orifice are formed entirely by the pre- 

 maxillae (PMx), which send processes up to join the nasals 

 and frontals. In front of the nares the face is prolonged 

 into a somewhat quadrate, depressed, alveolar process, trun- 

 cated in front, concave above, rounded laterally, formed by 

 the premaxillae above and at the sides, and by the maxillae 

 below. This contains the roots of the great incisor teeth 

 or tusks. 



