The Mammals and Man 



brained tvpe, the cranial capacity never, so far as is known, exceeds 

 600 cubic centimetres, whereas the average in man is about 1500, 

 and the smahest known about 930. Apart from the difference in 

 size, however, there is a surprisingly close similarity between the 

 anthropoid and the human brains, which may be followed even in 

 the particular arrangement of the fissures. That the gap betw^een 

 the two types m respect of the character in question is by no means 



A., 



C D 



Fig. 138. 



A, Lower jaw of Pelycodus, a primitive extinct lemur, with eleven teeth on either side ; 



B, Lower jaw of red howling monkey (a Western ape), with nine teeth on either side ; 



C, Lower jaw of chimpanzee, with eight teeth on either side ; D, Lower jaw of man. 



extraordinarily wdde may be seen from Fig. 137, in which a 



series of brains are depicted. The size of the hemispheres and 



the wrinkling of their surface are the characters from which we 



judge the brain development, and it is obvious that in these 



respects the step from the lower monkeys to the Chimpanzee is 



greater than that between the Chimpanzee and the lowest human 



type. In the teeth also, as is shown on Fig. 138, there is a gradual 



change from the lemur to the human type. 



149 



