276 ON THE RELATIONS OF 



skin in the Spider Monkey ; and is directed forwards and 

 armed \vith a curved claw like the other digits, in the 

 Marmosets so that, in all these cases, there can be no 

 doubt but that the hand is more different from that of the 

 Gorilla than the Gorilla's hand is from Man's. 



And as to the foot, the great toe of the Marmoset is still 

 more insignificant in proportion than that of the Orang 

 while in the Lemurs it is very large, and as completely 

 thumb-like and opposable as in the Gorilla but in these 

 animals the second toe is often irregularly modified, and in 

 some species the two principal bones of the tarsus, the 

 astragalus and the os calcis, are so immensely elongated as 

 to render the foot, so far, totally unlike that of any other 

 mammal. 



So with regard to the muscles. The short flexor of the 

 toes of the Gorilla differs from that of Man by the circum- 

 stance that one slip of the muscle is attached, not to the 

 heel bone, but to the tendons of the long flexors. The 

 lower apes depart from the Gorilla by an exaggeration of 

 the same character, two, three, or more, slips becoming 

 fixed to the long flexor tendons or by a multiplication 

 of the slips. Again, the Gorilla differs slightly from Man 

 in the mode of interlacing of the long flexor tendons: 

 and the lower apes differ from the Gorilla in exhibiting 

 yet other, sometimes very complex, arrangements of the 

 same parts, and occasionally in the absence of the acces- 

 sory fleshy bundle. 



Throughout all these modifications it must be recollected 

 that the foot loses no one of its essential characters. Every 

 Monkey and Lemur exhibits the characteristic arrangement 

 of tarsal bones, possesses a short flexor and short extensor 

 muscle, and a peronseus longus. Varied as the proportions 

 and appearance of the organ may be, the terminal division 

 of the hind limb remains, in plan and principle of construc- 

 tion, a foot, and never, in those respects, can be confounded 

 with a hand. 



Hardly any part of. the bodily frame, then, could be 

 found better calculated to illustrate the truth that the 

 structural differences between Man and the highest Ape 

 are of less value than those between the highest and the 

 lower Apes, than the hand or the foot, and yet, perhaps, 

 there is one organ the study of which enforces the same 

 conclusion in a still more striking manner and that is 

 the Brain. 



