386 Zoological Society : — 



muscles gain a proportional increase of carneous fibres, their bony 

 fulcra respond to the call for increased surface of attachment, the 

 sagittal and occipital crests begin to rise : but the brain grows no 

 more ; its cranial box retains the size it showed in immaturity ; it 

 finally becomes masked by the superinduced osseous developments 

 in those apes which attain the largest stature and wield the most 

 formidably armed jaws. Yet under this show of physical force, the 

 brain of both Orang and Chimpanzee is still the better and the larger, 

 than is that of the little long-armed ape, which retains throughout 

 life so much more of the charactei'S of immaturity, especially in the 

 structure of the skull. 



The Siamang and other Gibbons have smaller, lower but longer 

 upper canines, relatively, than in the Orangs and Chimpanzees ; the 

 permanent ones more quickly attain their full size, and are sooner in 

 their place in the jaws ; consequently the last molar teeth, m 3, come 

 last into place as they do in the human species. But, if this be 

 interpreted as of importance in determining the relative affinity of 

 the longer-armed and shorter-armed apes to man, it is a character in 

 which, as in their seeming superior cerebral development, the Hylo- 

 bates agree with some much lower Quadrumana with still smaller 

 canines. 



The systematic zoologist, pursuing this most interesting compa- 

 rison with clear knowledge of the true conditions and significance of 

 a globular cranium and small jaws within the quadrumanous order, 

 first determines and takes as his compass or guide-point the really 

 distinctive characters of the human organization. 



In respect to the cerebral test, he looks not so much for the rela- 

 tive size of the brain to the body, as for its relative size in the species 

 compared one with another in the same natural group. He inquires 

 what quadrumanous animal shows absolutely the biggest brain ? what 

 species shows the deepest and most numerous and winding convolu- 

 tions ? in which is the cerebrum largest, as compared with the cere- 

 bellum ? If he finds all these characters highest in the Gorilla, he 

 does not permit himself to be diverted from the just inference because 

 the great size and surpassing physical power attained in that species 

 mask the true data from obvious view. 



The comparative anatomist would look to the caecum and the 

 ischial integument : if he found in one subject of his comparisons 

 (Troglodytes) a long " appendix vermiformis caeci," as in man, but 

 no "callosities," — in another subject (Hylobates) the ischial callosi- 

 ties, but only a short rudiment of the csecal appendix, — he would 

 know which of the two tailless Apes were to be placed next " the 

 Monkeys with ischial callosities and no vermiform appendix," and 

 which of the two formed the closer link toward man. He would 

 find that the anthropoid intestinal and dermal characters were asso- 

 ciated with the absolutely larger and better developed brain in the 

 Gorilla, Chimpanzee, and Orang ; whilst the lower quadrumanous 

 characters exhibited by the caecum and nates were exhibited by the 

 smaller-brained and longer-armed but rounder-skulled and shorter- 

 jawed Gibbons. 



