204 



QUADRUMANA. 



degree to anticipate its total absence in the to account for that sedateness of character 



Colobi. This defect necessarily impairs the and indisposition to violent activity for which 



function of prehension in the Semnopitheci, they are so remarkable, 

 and, according to the views of Ogilby, helps 



Fig. 124,. 



Carpus of the Orang-cetan. (JF. Vrolik.) 



a, scaphoid ; ft, semilunar ; c, trique.trum ; d, trapezium ; e, trapezoides ; /, os magnum ; g, unci- 

 form; h, intermediaire bone; i, os sesamoideum for the tendon of the abductor longus pollicis. 



The femur of the Chimpanzee is slightly 

 bent in the anterior direction, as in the human 

 subject ; the neck of the bone has the same 

 comparative length, but stands out more ob- 

 liquely to the shaft. The whole of the bone 

 is flatter or more compressed from before 

 backwards. The head of the femur is at- 

 tached to the acetabulum by the ligamentum 

 teres, which is most remarkable, because it is 

 wanting in the Orang-cetan, and exists in the 

 other monkeys. The tibia in the Chimpanzee 

 is proportionally thicker at the upper end, 

 and the fibula considerably stronger at the 

 lower end than in man; the interosseous 

 space is wider, and the anterior convexity of 

 both bones may be perceived to be slightly 

 increased. The patellte are proportionally 

 smaller. The relative size and position of 

 the tarsal bones more nearly correspond to 

 the same in the human subject than is found 

 in any other quadrumanous animals ; but they 

 deviate nevertheless as much as is necessary 

 to produce that position of the foot which is 

 adopted for climbing, viz. on the exterior 

 edge of the foot, with the sole bent up, and 

 inwards. The os calcis is relatively weak, as 

 compared with that of man, being more com- 

 pressed from one side to the other, and smaller 

 in all its dimensions ; but it projects backwards 

 more than in the Orang-cetan or in the lower 

 Simice. From the inclination of the tarsus to 

 rest on its outer edge, the os naviculare is 

 further developed downwards, so as to pro- 

 ject considerably below the bones of the same 

 row, without inconvenience from pressure on 



the sole. The internal cuneiform bone has a 

 corresponding inclination, and thus the hallux 

 is attached to the tarsus, in a position best 

 adapted.for ita being opposed against the other 

 toes. The whole foot of the Chimpanzee is 

 relatively longer and narrower than in man ; 

 and the digital phalanges are more inflected 

 towards the sole. All these deviations are 

 still more apparent in the Orang-ceta'n, as I 

 have stated in my Recherches d'Anatomie comp. 

 sur le Chimpanse ; in which 1 compared the 

 anatomical disposition and the physiological 

 action of the foot of the Orang-cetan with 

 those of club-foot (pes varits). There can be 

 no doubt that this direction of the foot ren- 

 ders it unfit to support the animal upon a 

 level surface, while it is on the contrary very 

 convenient for the action of climbing. For 

 the same reason the hallux or the thumb of 

 the posterior extremities has a great deal of 

 mobility. I saw many times the two Orangs- 

 cetan of our gardens at Amsterdam grasp 

 objects with the hinder hand, scarcely with 

 less agility and ability than with the fore- 

 hand. The frequency of these movements of 

 the hinder thumb, and the friction it has to 

 support, when the animal climbs, seem to be 

 the cause why its nail and ungual phalanx 

 sometimes become atrophied, as I have proved 

 by many examples, and as may be concluded 

 also from the perusal of the works of Camper, 

 Temminck, Owen, Vosmaer, and Oskamp. 



In the Siamang, and in the other Gibbons, 

 the foot approaches more to the human than 

 in the Chimpanzee and Orang-cetan. The 



