767 



sinuses not being developed. The capacity of the cranium is almost equal to that in No. 5054, 

 and is consequently relatively much greater than the nasal chamber or the bones of the face 

 in the present immature specimen, which, in that respect, approaches nearer to the Human 

 characteristics. But the relative capacities of the cranial and olfactory chambers are not 

 absolutely indicative of degrees of proximity to Man in the Mammalian class, or in the Qua- 

 drumanous order. Some of the smaller species of the South American Monkeys, as, for ex- 

 ample, the Callithrix Pithecia, resemble the immature Orang in the predominating capacity 

 of the cranial chamber. This is due to a retention, with the diminutive size of the whole 

 body, of some other immature characters. The brain of the Callithrix is relatively larger in 

 proportion to the body than in the Chimpanzee and Orang, but it has a much less propor- 

 tional amount of grey cerebral matter ; the surface of the hemispheres being as little convo- 

 luted in the full-grown Marmoset as in the half-developed foetus of a larger and higher species 

 of Quadrumane. In the higher Mammalian classes the brain rapidly acquires a certain bulk 

 by an accelerated rate of growth : in all the Quadrumana, and doubtless in a much larger pro- 

 portion of the Mammalian class, the brain, at that stage of development as to bulk, bears the 

 same large proportion to the bulk of the embryo in all the species, notwithstanding the great 

 difference of size which may distinguish such species when arrived at maturity. The sub- 

 sequent differences in the relative size of the brain depend upon the specific stature ultimately 

 to be attained ; for, the destined degree of cerebral development in a large species having once 

 been obtained, as it is very rapidly in regard to the size of the hemispheres, the growth of 

 the trunk, limbs and jaws afterwards proceeds without corresponding growth of the brain. 

 These considerations must be allowed their due weight hi comparing the relative size of the 

 brain or brain-case of small and great species of the same Order of warm-blooded animals, 

 otherwise the same mistake may be made as to the relative perfection, or standing in the 

 group, of the smaller species with comparatively large brains, as has been made with regard 

 to the degree of relationship of the Chimpanzee and Orang to Mankind, when judged of by 

 the proportion of the brain and brain-case in small and immature individuals of those large 

 and formidable species of Ape. 



The great characteristic in Man arises from the great relative size of the brain and corre- 

 sponding capacity of the cranium being associated with a stature which surpasses that of the 

 largest of the Quadrumana. 



Presented by Prof. Owen, F.R.S. 



5081. A coloured plaster cast of the lower jaw of an adult male Orang-utan (Pi- 

 thecus Satyrus, var. Wurmbii}. Purchased. 



Genus Troglodytes. 



5082. The skeleton of an adult female Chimpanzee (Troglodytes niger). 



The vertebral formula is : 7 cervical, 1 3 dorsal, 4 lumbar, 6 sacral, and 2 caudal. The pleur- 

 apophysial portion of the transverse process of the atlas is shorter than in the Orang, and has 

 not united with the longer diapophysial division : the canal for the vertebral artery is thus not 



