12 ANTHEOPOID APES. 



and the boar. Simultaneously with these remark- 

 able alterations of the external structure there occurs 

 a modification of the skeleton. The skull of an 

 aged male gorilla becomes more prognathous, and 

 the incisor teeth have almost attained the length of 

 those of lions and tigers. On the upper part of 

 the skull, which is rounded in youth, great bony 

 crests are developed on the crown of the head and on 

 the occiput, and these are supported by the high, 

 spinous processes of the cervical vertebrae, and thus 

 supply the starting-point for the powerful muscles 

 of the neck and jaw. The supra-orbital arches are 

 covered with wrinkled skin, and the already savage, 

 and indeed revolting, appearance of the old gorilla 

 is thereby increased. A comparison of the two 

 illustrations (Pigs. 1 and 3) which accompany the 

 text, will make this clear. 



These distinctions are not so striking in the 

 female as in the male gorilla. Although there is 

 much which is bestial in the appearance of an aged 

 female, yet the crests, so strongly marked in the 

 male, the projecting orbits, and strong muscular pads 

 are absent in the female, as well as the prognathous 

 form of the skull and the length and thickness of 

 the canine teeth. The aged female gorilla is not, 

 in her whole structure, so far removed from the con- 

 dition of the same sex in youth as is the aged male. 

 The structure of the female has on the whole more 

 in common with the human form. It has been said, 

 and indeed on good authority, that the female type 

 should take the foremost place in the study of the 

 animal structure, since it is the more universal. 



