In Huxley’s opinion, the hinder limbs of the gorilla terminate in a true foot, with a very movable great toe. It is undoubtedly a prehensile foot, but in no sense a hand. It is a foot which does not differ from the human foot in any essential characteristics, but only in relative circumstances, in the degree of flexibility, and in the subordinate arrangements of its parts. Huxley adds that it must not be supposed that he wishes to undervalue differences which, however, he does not regard as fundamental. They are important enough of their kind, since in any case the structure of the foot is in close correlation with the other parts of the organism. Although it cannot be doubted that the increased division of labour in man, which relegates the function of support entirely to the legs and feet, is a significant advance in structure; yet, regarded as a whole from the anatomical point of view, the points of agreement between the human foot and that of the gorilla are much more striking and significant than their differences. The differences in the foot of the orang are still greater; in the very long toes and short tarsus, the short great toe and the removal of the heel from the ground, in the great obliquity of the joints which connect the foot with the shank-bones, and in the absence of a long flexor muscle to move the great toe, the orang’s foot differs still more from that of the gorilla than the latter differs from the human foot. In some of the lower apes the hands and feet are still further removed from those of the gorilla than in the case of the orang. In the American apes the thumb can no longer be opposed; in the ateles it is reduced to a mere rudiment, covered with skin; in the sahius it is bent forwards and provided with a curved claw like the other fingers. In all these cases there is no doubt that the hand differs more from that of the gorilla than the gorilla’s hand differs from that of man.[58] Flower remarks that the chief distinction between the foot of a man and an ape consists in the fact that the latter is transformed into a prehensile organ. The tarsal and metatarsal bones, and the phalanges are of the same number in both orders, and in the same relative position, only in the foot of the ape the facet for articulation of the first cuneiform bone with the great toe is saddle-shaped, and obliquely directed towards the inner or tibial side of the foot. Thus, the great toe is separated from the others, and so placed, that when it is bent, it is directed downwards towards the sole, and is opposed to the other toes, much more opposed to them than is the case with the thumb of the human hand.[59] Owen also speaks of the characteristic transformation of the great toe of an ape’s foot into a thumb, opposed to the other toes, and adapted for grasping.[60] [Illustration: Fig. 47.--Coaita (_Ateles paniscus_).]