77 



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 what 

 we call the ' wisdom-teeth ' 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 Hylobates agree with some much 

 lower Quadrumana with still smaller canines. The comparative 

 anatomist, pursuing this most interesting comparison with clear 

 knowledge of the true conditions and significance of a globular 

 cranium and small jaws within the quadrumanous order, turns 

 his attention to the true distinctive characters of the human 

 organization. 



In respect to the brain, he would look not so much for its 

 relative size to the body, as for its relative size in the species 

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

 inquire what quadrumanous animal shews absolutely the biggest 

 brain ? what species shows the deepest and most numerous and 

 winding convolutions? in which is the cerebrum largest, as com- 

 pared with the cerebellum 1 ? If he found all these characters 

 highest in the gorilla, he would not be diverted from the just 

 inference because the great size and surpassing physical power 

 attained in that species masked 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 cseci,' as in man, but 

 no 'callosities,' and in another subject (Hylobates) the ischial 

 callosities 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 formed the closer link toward man. He would find that 

 the anthropoid intestinal and dermal characters were associated with 

 the absolutely larger and better developed brain in the gorilla, 

 chimpanzee, and orang ; whilst the lower quadrumanous characters 

 exhibited by the csecum and nates were exhibited by the smaller- 

 brained and longer-armed tailless gibbons. 



Pursuing the comparison through the complexities of the bony 



