322 ANATOMY OE VERTEBRATES. 



the three true molars are supported by two distinct and well- 

 developed antero-posteriorly compressed divergent fangs ; in the 

 white and yellow races of the human subject these fangs are 

 usually connate in m 3, and sometimes also in m 2. The molar 

 series in both species of Troglodytes forms a straight line, with a 

 slight tendency, in the upper jaw, to bend in the opposite direc- 

 tion to the well-marked curve which the same series describes in 

 the human subject. 



This difference of arrangement, with the more complex implan- 

 tation of the premolars, the proportionally larger size of the incisors 

 as compared with the molars ; the still greater relative magnitude 

 of the canines; and, above all, the sexual distinction in that respect 

 illustrated by figs. 253 and 254, stamp the Gorillas and Chim- 

 panzees, fig. 256, most decisively with not merely specific but 

 generic distinctive characters as compared with Man. For the 

 teeth are fashioned in their shape and proportions in the dark 

 recesses of their closed formative alveoli, and do not come into the 

 sphere of operation of external modifying causes until the full size 

 of the crowns has been acquired. The formidable natural weapons 

 of the males of both species of Troglodytes, form the compensation 

 for the want of that psychical capacity to forge or fashion de- 

 structive instruments which has been reserved, as his exclusive 

 prerogative, for Man. Both Chimpanzees and Orangs differ from 

 the human subject in the order of the development of the perma- 

 nent series of teeth ; the second molar, m 2, comes into place before 

 either of the premolars has cut the gum, and the last molar, m 3, 

 is acquired before the canine. We may well suppose that the 

 larger grinders are earlier required by the frugivorous Chim- 

 panzees and Orangs than by the higher organised omnivorous 

 and longer nursed Bimanal, with more numerous and varied re- 

 sources, and probably one main condition of the earlier develop- 

 ment of the canines and premolars in Man may be their smaller 

 relative size. 



F. Bimana. Having reached, in the Gorilla, the highest step 

 in the series of the brute creation, our succeeding survey of the 

 dental system, cleared and expanded by retrospective comparison, 

 becomes fraught with peculiar interest, since every difference so 

 detected establishes the true and essential characteristics of that 

 part of man's frame. 



The human teeth are the same in number and in kind as those 

 of the catarhine Quadrumana. The bimanal dental formula is 

 therefore — 



.2.2 1.1 2.2 3.3 nn 



