10 



Gorilla, Chimpanzee, or Orang, be compared with a young Siamang 

 of corresponding age, the absolutely larger size and better shape of 

 brain, the deeper and more numerous convolutions of the cerebrum, 

 and the more completely covered cerebellum in the former, unequi- 

 vocally demonstrate the higher organization of the shorter-armed 

 Apes. "In the structure of the brain," writes Vrolik,* in accord- 

 ance with all other comparative anatomists, "they" (Chimpanzee 

 and Orang-utan) " approach the nearest to man." The degree to 

 which the Chimpanzee and Orang so resembled the human type 

 seemed much closer to Cuvier, who knew those great apes only in 

 their immaturity, with their small milk-teeth and precociously de- 

 veloped brain. Accordingly, the anthropoid characters of the Simia 

 satyrus and Simia troglodytes, as deduced from the facial angle and 

 dentition, are proportionally exaggerated in the "Regne Animal." f 

 As growth proceeds, the milk-teeth are shed, the jaws expand, the 

 great canines succeed their diminutive representatives, the temporal 

 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 characters 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 



* Art. Quadrumana, " Cyclopaedia of Anatomv," vol. iv. p. 195. 

 f Ed. 1829, pp. 87, 89. 



