The changes from the lower true mammals to the apes are of great interest, but we can notice only one or two of the more important. The prosimii, or "half apes," including the lemurs, are nearly all arboreal forms. Perhaps they were driven to this life by their more powerful competitors. The arboreal life developed the fingers and toes, and most of these end, not with a claw, but with a nail. The little group has much diversity of structure, and at present finds its home mainly in Madagascar; though in earlier times apparently occurring all over the globe. The brain is more highly developed than in the average mammal, but far inferior to that of the apes. They have a fairly opposable thumb. The highest mammals are the primates. Their characteristics are the following: Fingers and toes all armed with nails, the eyes comparatively near together and fully enclosed in a bony case. The cerebrum with well-developed furrows covers the other portions of the brain. There is but one pair of milk-glands, and these on the breast. The differences between hand and foot become most strongly marked by the "anthropoid" apes. These have become accustomed to an upright gait in their climbing; hence the feet are used for supporting the body and the hands for grasping. Both thumb and great toe are opposable; but the foot is a true foot, and the hand a true hand, in anatomical structure. The face, hands, and feet have mainly lost the covering of hair. They have no tail, or rather its rudiments are concealed beneath the skin. These include the gibbon, the orang, the gorilla, and the chimpanzee. We can sum up the few attainments of mammals in a line. The lower forms attained the placental mode of embryonic development; the higher attained upright gait, hands and feet, and a great increase of brain. Anatomically considered these were but trifles, but the addition of these trifles revolutionized life on the globe. The principal anatomical differences between man and the anthropoid ape are the following: Man is a strictly erect animal. The foot of the ape is less fitted for walking on the ground, where he usually "goes on all fours." The skull is almost balanced on the condyles by which it articulates with the neck, and has but slight tendency to tip forward. The facial portion, nose and jaws, is less developed and retracted beneath the larger cranium or brain-case. This has greatly changed the appearance of the head. Protruding jaws and chin, even when combined with large cranium and brain, always give man the appearance of brutality and low intelligence.