animals—its place in the scale of animated beings—as also its relations to space and time; that is, its distribution over the earth's surface to-day, in connection with that of other animals more or less like it, and its relation to the past life of this planet, in connection with similar relations of animals also more or less like it. In other words, to understand what a kangaroo is, we must understand its zoölogical, geographical, and geological conditions. And my task in this paper is to make these conditions as clear as I can, and so to enable the reader to really answer the question, "What is a kangaroo?"
But before proceeding to these matters, let us look at our kangaroo a little closer, and learn something of its structure, habits, and history, so as to have some clear conceptions of the kangaroo considered by itself, before considering its relations with the universe (animate and inanimate) about it.
The kangaroo (Fig. 1) is a quadruped, with very long hind-limbs and a long and rather thick tail. Its head possesses rather a long muzzle, somewhat like that of a deer, with a pair of rather long ears. Each fore-paw has five toes, urnished with claws. Each hind-limb has but two large and conspicuous toes, the inner one of which is much the larger, and bears a very long and strong claw (Fig. 2). On the inner
Fig. 2.—Foot of Kangaroo.
side of this is what appears to be a very minute toe, furnished with two small claws. An examination of the bones of the foot shows us, however, that it really consists of two very slender toes united together in a common fold of skin. These toes answer to the second and third toes of our own foot, and there is no representative of our great-toe—not even that part of it which is inclosed in the substance of our foot, called the inner metatarsal bone. Two other points are specially noteworthy in the skeleton. The first of these is that the pelvis (or bony girdle to which the hind-limbs are articulated, and by which they are connected with the back-bone) has two elongated bones extending upward from its superior margin in front (Fig. 4, a). These are called marsupial bones, and lie within the flesh of the front of the animal's belly. The other point is that the lower, hinder portion of each side of the lower jaw (which portion is technically called the "angle") is bent inward, or "inflected," and not continued directly backward in the same plane as the rest of the lower jaw.
A certain muscle, called the cremaster muscle, is attached to each
