367 



it is reverted to the elbow; backs of hands naked to the wrist; muzzle with 

 a scanty beard of very short white hairs; skin of the face dusky black, 

 darker round the eyes; ears and palms a dusky purplish black; hair 

 glossy black. 



Height from heel to top of head . . . . . . . .2 



Length of arm from shoulder to end of fingers .... 1 



Height from heel to extremity of thigh-bone . . . . . 



Hand, from wrist to end of middle finger .....0 



Circumference of hand .......... 



Breadth of palm .......... 



From heel to extremity of longest toe (middle) ..... 



Breadth of sole at origin of thumb ....... 



Length of ear upward .......... 



Transverse diameter of ear ........ 



5? 



4 



2 



5 



2 j 



2| 



If 



256 



Skull of young Chimpanzee. 



In the young Chimpanzee, during the first few years of its life, pre- 

 viously to the acquisition of the permanent teeth, the cranium (fig. 256), 

 owing to the early development of the brain, greatly preponderates 



over the face ; hence the facial angle is 

 more open than in the adult : the depth of 

 the lower jaw is also proportionally less, 

 and the zygoma more slender. The 

 cranium arches well from the supra- 

 orbital ridge, and, altogether, its simi- 

 larity to the human skull is very close. 

 With the process of the second dentition 

 a change takes place, both in the relative 

 proportions and position of the parts com- 

 posing it. The forehead sinks below the 

 bold supra-orbital ridge; the jaws ex- 



the volume of the face enlarges, and preponderates over that of the 

 cranium ; and the zygomatic arch becomes robust. A great, and, in many 

 particulars, an unexpected difference exists between the skulls of the adult 



male and female. In the adult female, the 

 cranium (fig. 257) is of an ovate form, 

 depressed above, narrow, and destitute of 

 the strong frontal and interparietal crests, 

 so conspicuous in the Orang ; the extent 

 of the temporal muzzle is, however, 

 marked by an osseous border, commenc- 

 ing boldly from the outer part of the 

 supra-orbital ridge, but soon diminishing 

 skuii of aduit f^ie chimpanzee. to * rou g h and slightly raised line, which 



traverses the parietal bone, and joins the 



lambdoidal ridge, which latter is not developed in the immature animal, 

 and is never so strong as in the Orang. The volume of the cranium 



pand 



257 



