“Whilst the Kangaroos of the plain have the fore part of the body slender and light, great strength in the hinder parts, combined with a long leg and foot, adapting them to fleetness, the tail powerful, and assisting in the support of the long body, we perceive certain modifications in the form and structure of these parts in the Rock Kangaroos which adapt them to their particular habitats. The body, more compact in form, requires but little assistance from the tail for its support, the leverage being less; and the feet are, though powerful, comparatively short, and remarkably rough beneath, being thickly covered over this part with hard tubercles, which no doubt prevent the foot from slipping. The nails of the two larger toes are shorter than usual, and, indeed, in some of the species, scarcely project beyond the fleshy pads with which the toes are terminated, and on the upper surface of which the nails are placed. A long and slender foot, with long nails, as in the typical Kangaroos, it is obvious, would be ill-adapted to an animal which has to leap to and balance itself upon the small ledges of the rocks. The tail is large, but not thickened at the root, as in the plain Kangaroos; and, unlike the tail in those animals, it is clothed with long hairs, which, gradually increasing in length from the base of the tail, become very long and bushy at the opposite extremity. It serves to steady the animal in its leaps, and to balance the body when perched in situations which require it, but is of little assistance in supporting the weight of the trunk. Its muffle, that is to say, the end of the nose, is naked, as in the scrub-inhabiting Kangaroos just noticed, and it forms the type of the sub-genus _Heteropus_” (ἕτερος, altered, πούς, foot). One of these was hunted and shot amongst the woods of Liverpool plains, New South Wales, by Sir Edward Parry, who wrote that they appear to be gregarious, and seem to prefer the neighbourhood of rocky ground, in which they had holes, and to which, when hunted, they retreated. They swarm along in groups one after the other, and jump from side to side, alighting on ledges so slightly prominent that their resting thereon appears to be an impossibility. They go into caves and holes in the rocks during the day, and they enjoy the night, and gambol and feed by moonlight. A Rock Kangaroo, with white and black bands on it, inhabits Western Australia, and a short-eared kind enjoys the hot sands and high rocks of Hanover Bay. There is a Kangaroo in the island of New Guinea (_Macropus Brunii_), and it was the first seen by Europeans. THE COMMON TREE KANGAROO.[92] [Illustration: COMMON TREE KANGAROO.]