552 ZOOLOGY sect. 



neiim, attached to wliicli by means of ligamentous fibres is a 

 slender rod of bone or cartilage, the calcar, which supports the 

 inter-femoral membrane. 



Fifi. 1175.— Skull of Pteropus fuscus. (After Blaiiivilk>.) 



Skeleton of the Primates. — The atlas is ring-like, the 

 odontoid sub-conical The spines of the cervical vertebra are 

 usually well-developed and simple : in Man they are short — with 

 the exception of the seventh — and bifid : in some they are trifid. 

 The number of thoraco-lumbar vertebrse is usually nineteen, 

 but only seventeen in Man, the Gorill.a and Chimpanzee, sixteen 

 in the Orang ; in some Lemurs it may be twenty-three or 

 twenty-four. The number of sacral vertebrje varies from two to five. 

 The sacral region of Man, which comprises five ankylosed vertebra^, 

 differs from that of other Primates in its greater relative breadth 

 and in its backward curvature ; it forms a well-marked angle 

 where it joins the lumbar region — the sacro-vertehral angle — scarcely 

 recognisable in other Mammals. The number of caudal vertebrae 

 varies with the length of the tail — from four to about thirty- 

 three. In Man there are only four vestigial caudal vertebra\ anky- 

 losed together to form the coccyx. In all those forms in which the 

 tail is well developed chevron bones are present. 



The IwxTawa skull (Fig. 1176) presents a marked contrast in 

 certain respects to tliat of other Mammals, but in many points is 

 approached by that of the other Primates, more especially by that 

 of the Simiida\ One of the most important characteristics of the 

 human skull is the large size of the brain-case, the cubic contents 

 of the cranial cavity averaging 1500 cubic centimetres in the male 

 of white races. This great development is most marked in that 

 part of the cavity which lodges the cerebral hemispheres, in adapta- 

 tion to the large dimensions of which the cranium bulges out both 

 anteriorly and posteriorly to such an extent that the entire length 



