FEMUR, COM PA RA T1 VE ANATOMY Or. Al. though certain conipa rati ye anatomists have at tempted to find in the mint opterygium of the fin of a fish a homologue of the femur, it is beyond question that such a bone is not actually found below the more or less terrestrial amphibians. In the members of that class (Uro dela) the femur is a short and relatively unim portant bone; but in thole forms whose chief mode of progression is by leaping (Acura), it becomes the longest and most important bone of the hind limb. Among reptiles we find the femur, when present, a short but very stout bone, reaching its strongest development among the Crocodilia, though the lizards and turtles are nut far behind. Among snakes, a femur is pres ent only in the families Tortriehhe and Pythoni d;r, and in those eases it is greatly aborted. The femur is sometimes lacking in lizards, and in other cases is rudimentary. Among birds the femur is a short, stout bone imbedded in muscles and concealed beneath the skin; its upper, ar ticular end is rounded and almost at a right angle with the main shaft; the terminal condyles are large and on the outer is a ridge which plays between the heads of tibia and fibula. Most
mammals possess a well-developed femur, the relative length of which depends very largely upon the habits of the animal and the propor tions existing between the fore and hind limbs. No femur is present in the manatee or the dugong, and it is wanting also in most of the Cetacea. In some whales, however, which possess a rudi mentary pelvic girdle, a small bone lying just outside the latter is thought to represent the femur. Monkeys possess femurs most nearly like that of man, and this is e-speeially true of the anthropoid apes; yet even the gorilla, which in this respect is the most man-like of all the apes, has certain peculiarities of the femur by which the expert can distinguish it from man. These dif ferences between the femurs of apes and man are so readily recognized that when the famous re mains of Pithecanthropus erect us were found in Java by Dubois, their position. intermediate be tween man, whom they approach in cranial char acter, and apes, was determined by the examina tion of the femur, this hone showing certain pitheeoid characters quite strongly.