Every part of these animals is so altered and specialised from the usual type of Mammalian structure as to assist in the best possible way the capturing, killing, and devouring of living prey. Looking merely at the outside, we are struck with the lithe, agile form, the small head, the total absence of anything like a “pot-belly,” the well-proportioned limbs, the usually close fur, the stealthy, silent movements, and the eager, restless glance: all characters suited to an animal to which powers of quiet rapid movement through jungle or long grass, of quick observation, and of great strength and agility, are of the utmost importance. In the skeleton there are two points of importance, as relating both to the habits of the Cat tribe and to the determining of their systematic position in zoology. These are the character of the skull, and the structure and arrangement of the bones of the toes. Both these points furnish characters by which the Cats may be separated from all other families. To these two points, therefore, we will proceed at once, as, without going into lesser details, there is nothing of special importance in the vertebral column, large limb bones, &c. All the points mentioned in the introduction to the group as being characteristic of the Carnivorous type of skull are here carried to their extreme. The bony ridges for the attachment of the jaw-muscles are immense; the jaws attain their utmost limit of structure and strength, and the lower jaw being perfectly incapable of motion from side to side, the teeth, as we shall see by-and-by, act like scissors and not like mill-stones. If the skull of a Cat be examined, there will be seen on its under surface, near the hinder end, a pair of rounded swellings, directed somewhat obliquely. On looking at the skull from the side, there is seen to be a roundish aperture, the auditory meatus, leading into each of these swellings, which are found to be thin-walled half globes, stuck on, as it were, to the under surface of the skull. Round the aperture is fixed, in the living state, the Cat’s prominent external ear, and stretched across it, like the parchment of a drum, is a thin membrane, which vibrates with every sound. The rounded cavity is called the “drum of the ear,” the membrane stretched across it the “drum membrane,” or “tympanic membrane,” and the bony half-globe, which forms the floor of the drum cavity, is the “bulb of the drum,” or _bulla tympani_. [Illustration: SIDE VIEW OF LION’S SKULL. _a.m_, auditory meatus; _b.ty_, bulla tympani; _j_, jugal arch or zygoma; _o.c_, occipital condyle for the articulation of the skull with the first vertebra; _c_, condyle of the lower jaw; _g_, glenoid cavity with which the condyle of the lower jaw articulates; _p_, the bony clamp, or paroccipital process.]