It is important to remark that platycnemy has been regarded as a pithecoid structure, and for this reason the attempt has been made to establish the degraded position of those peoples which are most remarkable for platycnemy. But, as Boyd-Dawkins has already observed, although the tibiæ of the gorilla and the chimpanzee are to some extent platycnemic, they are much less so than the platycnemic bones of the human skeleton. The tibia of a male gorilla in the College of Surgeons Museum has an index width of 68·1, that of a female of 65·0, while the index of the chimpanzee’s tibia is 61·1, which is about the average of the tibias of Perthichwareu. It is unnecessary to indicate the other marked distinctions between the tibiæ of men and apes; if platycnemy is to be regarded as genetic, it must be admitted that man has in this particular far exceeded apes.[57] Neither the gorilla, the chimpanzee, the orang-utan, nor even the baboon possesses a tibia which is flattened in its upper or middle part. In all these apes the middle of the bone is more or less rounded, almost as if it had been rounded by a turning-lathe. According to my experience, the degree of platycnemy in anthropoids is subject to certain variations. It appears to me to be least marked in the aged male gorilla (Fig. 41), and in the gibbon (_Hylobates agilis_, _syndactylus_), in which latter animal the transverse section of the tibia represents an almost equilateral triangle. The platycnemy was more marked in an almost adult female gorilla, still more decided in an aged male chimpanzee, which came from the river Kiulu, and again in an aged female chimpanzee. On the other hand, the centre of the shaft of the tibia in another aged male chimpanzee which came from Loango, was rounded, and not platycnemic. In the tibia of an adult orang-utan which I examined, the platycnemy was very marked. But I agree with Boyd-Dawkins in never having met with an anthropoid in which the platycnemy is so considerable as it is, for instance, in the Cro-Magnon tibia, and in another found at Troy. [Illustration: Fig. 46.--Skeleton of the human foot, seen from above. _a_, Astragalus. _b_, Os calcis. _c_, Scaphoid bone. _d_, _e_, _f_, Cuneiform bones. _g_, Cuboid bone. _h_, Metatarsal bones. _ii_, Phalanges. ] If we give a cursory glance at the lower limbs of apes, we see that all the same characteristics are present in their tarsus that we find in the human tarsus. In each case there is an astragalus, an _os calcis_, a scaphoid bone, three cuneiform bones, and a cuboid bone. There are undoubtedly several peculiarities in which the tarsus differs from the corresponding part of the human foot. The first metatarsal bone is joined to the first cuneiform bone by an articular facet which extends from the back to the sole of the foot. This joint plays a part resembling that of the thumb of the human hand (see Figs. 20 and 46).