That kangaroos, like all marsupials, bring forth their young in an exceedingly imperfect and helpless condition, it is almost unnecessary to mention; as is the fact that the females carry them in the pouch not only till they are able to take care of themselves, but, on occasion, till a much later period. Not that it is to be assumed from this that the young of all marsupials are carried in the maternal pouch; this being in some cases undeveloped, and the offspring in such instances merely clinging for a time to their mothers’ nipples. For a long time it was generally considered that marsupials were survivors of the ancestral stock which gave rise to the ordinary, and so-called placental, mammals; but this is now known to be a mistaken view, and marsupials and placentals are evidently divergent branches from a common ancestral stock. In Australia marsupials have developed almost as many different modifications as have the placentals in other parts of the world; and at first sight there seem few external characters in common to such diverse types as the leaping, bipedal, herbivorous kangaroo, and the cursorial and carnivorous Tasmanian wolf. When, however, the two animals are observed more closely, we may note a curious resemblance in the form of their heads, and, above all, by the great, thick tail, passing almost imperceptibly into the body; both these features proclaiming their comparatively near relationship and descent from a common ancestor. Among the external characteristics of the kangaroo tribe may be noted the somewhat deer-like head, the short fore-limbs, each armed with five toes, and used in progression only when the animal is grazing, and the enormous length and strength of the hind-legs, in which one toe is greatly developed at the expense of the rest, and serves not only to aid in progression, but forms an offensive weapon of great power and effectiveness. In the sitting posture, as represented in the illustration, the body is supported on a tripod formed by the massive tail and the hind-legs; the whole of the lower portion of the latter, corresponding structurally to the human foot, being then applied to the ground. When, however, the animal is leaping, as shown in the background of the picture, the hind part of the foot is raised and the body supported by the toes; the tail thumping on the ground at each leap. [Illustration]