&6 1TATUEAL HISTOET OF 



human form, and in its similarity points out the 

 unfitness of these animals for a constant quadruped 

 motion. The inferior structure of the hands, and 

 particularly the thumbs, show them fitted for grasping 

 alone, and incapable of performing any nice mecha- 

 nical operation, while the great comparative length 

 indicates their utility in climbing, and therefore their 

 fitness for an arboreal life. 



All the orangs which have been dissected, had 

 scarcely reached their second year. The relative pro- 

 portions, therefore, of the skull and brain to the body, 

 cannot be fixed or compared with those of the adult 

 human being. The relations of the brain, however, 

 as far as have been observed, are nearly similar, and 

 the principal differences in the skull of the nearest 

 form, the black orang, are thus mentioned by Dr Trail: 

 " The top of the head is more flat, and its union 

 with the spine farther back. The orbital processes of 

 the os frontis project about half an inch beyond the 

 general convexity of that bone ; and the orbits of the 

 eyes are proportionally larger and rounder than in 

 man. The depression which receives the cribriform 

 , plate of the ethmoid bone, is much deeper and smoother 

 on the sides; while the apertures in that bone, for 

 the passage of the olfactory nerves, are considerably 

 larger. Instead of the well-defined boundaries traced 

 in the human skull by the crucial ridge, they were 

 marked by a flat undulation of the occipital bone. 

 There is no mastoid, and scarcely a vestige of a hyloid 



