SKULL. 237 



SKULL. The skull varies greatly in different individuals, 

 even of the same sex, not only in its general form, but in the 

 shape of its different bones. In the males the occipital and me- 

 dial crests are not much developed before the fifth or sixth 

 year. The bones thicken greatly after the animal attains ma- 

 turity, and the palate becomes more flattened. In the adult 

 male the brain-box may be described as subquadrate, nar- 

 rower anteriorly, where the skull is abruptly contracted. The 

 greatest diameter of the skull is at the posterior end of the 

 zygoma, and is equal to three-fifths of its length. The post- 

 orbital processes are strongly developed and quadrate; the fore- 

 head is flat, and the facial profile is either abruptly or grad- 

 ually declined; the muzzle is broad, its breadth at the canines 

 being rather more than one-fourth the total length of the skull. 

 The palatal surface of the intermaxillaries is flat, or slightly de- 

 pressed anteriorly, and very slightly contracted posteriorly. Lat- 

 erally the mtermaxillaries reach nearly to the end of the palatals. 

 The latter are much contracted posteriorly, and terminate quite 

 far in front of the hainuli pterygoidei. Both the anterior and 

 posterior nares are a little narrower than high. The nasals are 

 widest anteriorly. The last (fifth) pair of upper molars is placed 

 far behind the fourth pair, the space between them being about 

 equal to that occupied by two molars. The males in old age 

 have exceedingly high occipital and sagittal crests, most devel- 

 oped posteriorly; anteriorly they diverge and terminate in the 

 hinder edge of the postorbital processes. 



The lower jaw is massive and strong. Its coronoid processes 

 are greatly developed, as are the tuberosities at the angle of 

 the rami, and a second tuberosity on the lower inner edge of 

 each rarnus. 



The skull in the female is not only much smaller than in the 

 male, but lacks entirely the high crests seen in the male, and 

 all the processes are much less developed. The teeth, espe- 

 cially the canines, are much smaller, and the bones are all thin- 

 ner and weaker, the weight of the adult female skull being- 

 only about one-third of that of the male of corresponding age. 

 The skull of a full-grown female of this species attains only 

 about the linear dimensions of an adult male skull of CaUorJiinus 

 ur sinus. 



