Mr. R. Foulerton, who has paid some attention to the habits of the Marsupials, writes that the Great Kangaroo, although its numbers have been greatly diminished in some pastoral districts, still is numerous enough to render some runs almost worthless for pastoral purposes. They may be seen there in thousands, eating off all the best grass, and in the bad seasons reducing the cattle to starving point. They have few enemies but man, as even the native Dog will never attack them, unless they are very young. An “old man” Kangaroo is a formidable opponent; he will severely wound and even kill a man, unless approached cautiously. Their mode of attack is to “hug” him bear fashion, and then rip him with the hind foot. When pursued, they generally take to the water, and there stand at bay, and the luckless man or dog who gets within their grasp is forced under the water, and held there until drowned. The middle-aged Kangaroos, or Flyers, easily outstrip the hunting Dogs at the start, but they are gradually gained upon. When caught, the Kangaroo fights to the last.
The diminutive fore limbs are separated by narrow shoulders, and although the upper arm is short and well furnished with muscles, the fore arm is long, slender, but very movable. The hand is short and broad, and there are four curved, sharp claws, the first one, or thumb, being the smallest, and the third and fourth the largest. The hair covers over the fingers to the claws, which can separate widely, grasp and hold, and be bent on the palm. The movements of the wrists and fore arms are considerable, and a large and long upward-turning muscle is in the space between the ulna and radius (the bones of the arm). Moreover, the ulna joints with a cavity in the cuneiform bone of the wrist; and the first row of wrist bones has three in it, and the second has four. The first phalanges, or those of the thumb, are not placed as a thumb in relation to the wrist bones, and it is the outer fingers that grasp with their claws. As the Kangaroo has to lift up its arm, there is a collar-bone, and the arm bone (humerus) is perforated on the inner side of the end above the elbow; and the olecranon is long.
The bladebone has a curved ridge, and the muscles of the upper part are less than those which are attached to the part below it. There are thirteen pairs of ribs to the chest.
The skull is long and comparatively smooth, and even the ridges for the temporal muscles are only slightly raised; and in old Kangaroos the bones do not unite or anchylose as they do in the other Mammalia hitherto noticed. The teeth are not used as weapons of offence, but simply to graze with, and the lower jaw is not quite solid at the chin, but only so below, so that the lower incisors can be slightly separated. The ear-bone is remarkable for being separated into three parts, namely, the temporal or squamous, the petrosal, and the tympanic; and this is rather a reptilian character. Moreover, the air-chambers of the side of the under part of the skull are in the form of rounded prominences, or “bullæ.” They are situated in the lower part of the ear-bone, called squamosal. The zygoma, or process between the cheek (malar) bone and the ear, is hollow, complete, and arched, its front part being, moreover, extended downwards in a projection which reaches below the grinding teeth, and resembles that of the Sloths somewhat. The lower jaw has its back part, or angle, bent inwards (or inflected) strongly, and this is, except in one set, a characteristic of the Marsupiata.
STOMACH OF THE GREAT KANGAROO.
(œ) œsophagus; (in) intestine.
The Kangaroo, being a vegetable feeder, has a stomach suited for the diet, which also permits of a certain amount of regurgitation of food up again into the mouth, when a kind of chewing of the cud occasionally is indulged in. The stomach is large and long, resembling the colon or large intestine of the highest Mammalia in its general shape. It measured, in one instance, according to Owen, no less than three feet six inches, the measurement following its bends or curvatures. It consists of a left, middle, and right or pyloric division. The left ends in two round sacs, and these are really continuations of the stomach separated to a certain extent by a peculiar arrangement of the three bands of muscular fibres which pass separately along the organ. Numerous clusters of secreting glands are found in the mucous membrane of the stomach in its middle part, and they disappear near the pylorus where the tissues are thick and corrugated. The animal has a small intestine, a cæcum, and a large gut, but this last is not much larger than the first part of the stomach. The organs of the circulation of the blood resemble those of the other Mammalia, but there is a distinction which relates to the short period during which the young Kangaroo is a portion of the maternal being. So soon is it born, and so soon therefore must it breathe, that before the heart has grown much, it has the blood from the lungs and the rest of the body running through it. The young Kangaroo breathes when its heart is not fully developed, yet it has the perfect double circulation set up. The auricles of the heart communicate as in other Mammals until birth, but the duration of this communication is very short in the Marsupial, and its traces so evident in the other Mammals are wanting in it. The arteries of the body are simpler than in those Mammals which have a more complicated intestinal arrangement, and Owen, in his great work on the Marsupials, has pointed out that the hind limbs and tail are supplied with arterial blood by vessels which have an arrangement not without its similarity to that of birds. Leading a very simple life, and one of great sameness, moving in a manner which does not require much complexity of muscular action, the nervous system of the Kangaroo could not be expected to be highly organised or fully developed. The brain is small for the body of the animal. It is simple in form, and does not cover the cerebellum, which is visible behind, and has a little lobe on each side. The surface of the brain proper has a few convolutions on it, and more perhaps than the Rodent Mammalia have. The commissures of the brain, which relate to the complexity of the method of life, are unequally developed. The central one, or the corpus callosum, is small, and the front one is very large. Finally, the part of the brain which refers to the sense of smell is large, but hidden by the brain proper, and its nerves supply a large surface in the nose, at its upper part at the base of its skull.
BRAIN OF THE GREAT KANGAROO.
The young Kangaroo, when very small, and almost transparent, comes down from the womb into a canal, and gets into the uro-genital sac, as it is termed. Thence it is taken by the mother, and put into the marsupium, or pouch, where it fixes on to a nipple, and holds on. As the little one is ever “at the breast,” it might have any quantity of milk go the wrong way, but this is provided for by the upper part of the organ of voice (the larynx) being prolonged at the back of the nose, above the level of the long nipple. Breathing goes on through the nose, and swallowing safely through the gullet.