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