11 



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 cseci," 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 csecum and nates were exhibited by the 

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

 jawed Gibbons. 



Pursuing the comparison through the complexities of the bony 

 framework, he might first glance at the more obvious proportions ; 

 and such, indeed, as would be given by the entire animal. The 

 characteristics of the limbs in Man are their near equality of length, 

 but the lower limbs are the longest. The arms in Man reach to 

 below the middle of the thigh ; in the Gorilla they nearly attain 

 the knee ; in the Chimpanzee they reach below the knee ; in the 

 Orang they reach the ankle ; in the Siamang they reach the sole ; 

 in most Gibbons the whole palm can be applied to the ground 

 without the trunk being bent forward beyond its naturally inclined 

 position on the legs. These gradational differences coincide with 

 other characters determining the relative proximity to Man of the 

 apes compared. In no Quadrumana does the humerus exceed the 

 ulna so much in length as in Man ; only in the most anthropoid, 

 viz. the Gorilla and (^/himpanzee, does it exceed the ulna at all in 

 length ; in the rest, as in the lower quadrupeds, the fore-arm is longer 

 than the arm. 



The humerus, in the Gorilla, though less long, compared with the 

 ulna, than in Man, is longer than in the Chimpanzee ; in the Orang 

 it is shorter than the ulna ; in the Siamang and other Gibbons it is 

 much shorter, the peculiar length of arm in those "long-armed" apes 

 is chiefly due to the excessive length of the antibrachial bones. 



The difference in the length of the upper limbs, as compared with 

 the trunk, is but little between Man and the Gorilla. The elbow- 

 joint in the Gorilla, as the arm hangs down, is opposite the " labrum 

 ilii," the wrist opposite the " tuber ischii ;" it is rather lower down 

 in the Chimpanzee ; it is opposite the knee-joint in the Orang ; it is 

 opposite the ankle-joint in the Siamang. 



Man's perfect hand is one of his peculiar physical characters ; 

 that perfection is mainly due to the extreme differentiation of the 

 first from the other four digits, and its concomitant power of oppo- 

 sing them as a perfect thumb. An opposable thumb is present in 

 the hand of most Qxiadrumana, but is usually a small appendage com- 



