388 Zoological Society : — 



flat, or present a concavity rather at the back than at the fore part. 

 In the Siamang they are not only flat, but are narrower and longer, 

 resembling the iliac bones of tailed monkeys and ordinary quadrupeds. 



The lower limbs, though characteristically short in the Gorilla, 

 are longer in proportion to the upper limbs, and also to the entire 

 trunk, than in the Chimpanzee ; they are much longer in both pro- 

 portions and more robust than in the Orangs or Gibbons. But the 

 guiding points of comparisons here are the heel and the hallux. 



The heel in the Gorilla makes a more decided backward projection 

 than in the Chimpanzee ; the heelbone is relatively thicker, deeper, 

 more expanded vertically at its hind end, beside being fully as long 

 as in the Chimpanzee : it is in the Gorilla shaped and proportioned 

 more like the human calcaneum than in any other ape. Among all 

 the tailless apes the calcaneum in the Siamang and other Gibbons 

 least resembles in its shape or proportional size that of Man. 



Although the foot be articulated to the leg with a slight inversion 

 of the sole it is more nearly plantigrade in the Gorilla than in the 

 Chimpanzee. TheOrang departs far, and the Gibbons farther, from 

 the human type in the inverted position of the foot. 



The great toe which forms the fulcrum in standing or walking is, 

 perhaps, the most characteristic peculiarity in the human structure ; 

 it is that modification which differentiates the foot from the hand, 

 and gives the character to the order Bimana. In the degree of its 

 approach to this development of the hallux the quadrumanous animal 

 makes a true step in affinity to Man. 



The Orang-utan and the Siamang, tried by this test, descend far 

 and abruptly below the Chimpanzee and Gorilla in the scale. In the 

 Orang the hallux does not reach to the end of the metacarpal of the 

 second toe ; in the Chimpanzee and Gorilla it reaches to the end of 

 the first phalanx of the second toe ; but in the Gorilla the hallux is 

 thicker and stronger than in the Chimpanzee. In both, however, 

 it is a true thumb, by position, diverging from the other toes, in the 

 Gorilla, at an angle of G0° from the axis of the foot. 

 * Man has twelve pairs of ribs, the Gorilla and Chimpanzee have 

 thirteen pairs, the Orangs have twelve pairs, the Gibbons have thir- 

 teen pairs. Were the naturalist to trust to this single character, 

 as some have trusted to the cranio -facial one, and in equal ignorance 

 of the real condition and value of both, he might think that the 

 Orangs (Pithecus) were nearer akin to man than the Chimpanzees 

 (Troglodytes) are. But man has sometimes a thirteenth pair of 

 ribs; and what we term "ribs" are but vertebral elements or 

 appendages common to nearly all the true vertebrae in man, and 

 only so called, when they become long and free. The genera Homo, 

 Troglodytes, and Pithecus, have precisely the same number of ver- 

 tebrae ; if Troglodytes, by the development and mobility of the pleur- 

 apophyses of the twentieth vertebra from the occiput, seem to have 

 an additional thoracic vertebra, it has one vertebra less in the lumbar 

 region. So, if there be, as has been observed, a difference in the 

 number of sacral vertebrae, it is merely due to a last lumbar having 

 coalesced with what we reckon as the first sacral vertebra in Man. 



