The natural food of all the cat tribe in a state of nature is carnivorous, and the whole organisation of the group is specialised and adapted for aggressive or, if need be, defensive purposes. The body is compressed laterally, and has a considerable amount of flexibility in it as a whole.

The bony framework or skeleton is light, and, for the purpose of an elementary description, is readily divisible into three parts - viz. (1) the skull; (2) the axial skeleton, comprising the bones of the neck, thorax, loins, and tail ; (3) the appendicular skeleton or limbs. The skull is short, rounded, and broad across the orbits or eye-sockets, which are large in proportion to the skull. The posterior rim of the orbit is, with three exceptions, out of the fifty-one species - viz. the fishing-cat (F. voverrina), the rusty spotted cat (F. rubiginosa), and the flat-headed cat (F. planiceps) - incomplete or open. The teeth of the fully adult cat should be thirty in number - sixteen in the upper jaw and fourteen in the lower. They are divided by the comparative anatomist into three sets or groups - viz. incisors, canines, premolars, and molars - their number and position being concisely expressed by a dental formula thus : - I'3/3, C. 1/1, PM.2/3, M. 1/1. The six incisors in the upper and lower jaw are small, simple-pointed teeth, with a simple fang or root. Then we have a long canine or flesh tooth C C', the most important functional tooth the cat has, for with it and its fellow the living, struggling prey is seized, retained, and killed.

In the upper jaw, immediately after the canine, are three premolars PM. These are the second or permanent series, and succeed the kitten's milk-teeth. The first one is very small, and has only a single cusp; the second is larger, and has two cusps; the third is the largest, and is sometimes called the " sectorial " tooth. It has three pointed cusps and three fangs, or roots. Immediately behind it, and placed somewhat transversely, is the single true molar. It is a small tooth, of obtuse form, and indefinitely cusped ; it has no predecessor in the kitten's milk set.

FIG. II. - Skull Of The Great Sabre-Toothed Cat. From The Caves Of Brazil. (Machoerodus Neogazus.)

Fig. IV. - Bones And Principal Ligaments Of A Cat's Toe, Showing Mechanism Of Retractile Claw A, Distal or terminal phalanx; B, Middle; c, Proximal; d, Perforatus tendon ; E, Perforans tendon ; F, Elastic ligament.

Fig. V. - Pads Of Cat's Left Fore-Foot A, Plantar pad ; B, Digital pad ; c, Pisiform pad.

In the lower jaw, immediately after the canine tooth, there are only two premolars (PM. PM'.) in the permanent set which have predecessors, the last tooth (M.) being the only true molar, and having no predecessor in the milk set. Occasionally, in the lower jaw there is a small premolar corresponding to the first premolar of the upper jaw. In the kitten from about six or seven weeks to about five months old, there are only twenty-six teeth, the number and form being very similar to the adult set. The two permanent molars in the upper and lower jaw are absent.

The Axial Skeleton (see p. 354) consists of the bones forming the neck, thorax, loins, and tail. The neck is relatively short, and consists of seven bones - a. number almost constant throughout the animal kingdom, the giraffe, the hippopotamus, and the whale having the same number. Succeeding these are the dorsal, or thoracic, vertebrae (thirteen in number), each one supporting two ribs - one on each side. Then follow the seven vertebras composing the lumbar region. They are stout, thick bones, with long, transverse processes for the attachment of certain muscles supporting the body cavity, etc. No ribs are attached to these bones. Immediately behind are three smaller bones forming the sacrum, to which the pelvis, or hip-bones, are articulated. The terminal bones of the axial skeleton are the tail, or caudal, and vary from nineteen to twenty-one.

The Ribs (thirteen on each side) are extremely light, elastic, and slender. Nine of these on each side join the sternum or breastbone directly, and are called true ribs ; the remainder are free, and terminate in cartilaginous points, which are adherent to the true rib terminations, for support.

The Sternum, or breast-bone, consists of eight bones, from each joint of which springs a rib-like costal cartilage, to which the true ribs are articulated. The cat's collar-bone or clavicle is very short and rudimentary ; it has a slight attachment to the acromion process of the scapula, the other end terminating in the muscles of the chest. It is often absent.

The Appendicular Skeleton includes the fore and hind limbs. The fore limb in the cat, as in the majority of mammals (see plate, P- 355). is a subtriangular flat bone, with a ridge on the outer side for the attachment of certain muscles moving the leg.

In a small hollow on the posterior or lower border is articulated the head of the humerus (4), or arm-bone ; its lower or distal end is expanded, and receives the end of the ulna (10), which with the radius (9) forms the bones of the forearm. The wrist or carpal bones (8) include seven small bones, the upper row being attached to the radius, the lower row to the five pha-langes of the toes (7); to these latter are articulated the bones of the digits, or fingers.

The terminal bones of the cat's foot are encased by powerful hooked claws (Fig. III.). When at rest, the claw is brought to the outer side of the middle phalanx by the elastic ligament F, the flexor tendons being relaxed. When the cat is on the point of seizing its prey, the greater power of the flexor tendons stretches the weaker elastic ligament, the claw is brought down, and so a powerful grip is obtained. The under-surface of the cat's fore and hind feet is protected by certain hardened pads of subcutaneous and fibrous tissue - viz. the plantar pad, giving chief support to the leg, and the digital pads protecting the claws, etc. These pads are, of course, of additional use in aiding the cat's noiseless and stealthy progression.

Fig. III. - Superficial Flexor Tendons Of The Cat's Left Fore-Foot A, Perforatus, or flexor subdigitorum ; B, Perforans, or flexor profundus digitorum.

Fig. VI.B. - Cat's Skull, Side View, With Lower Jaw In Place

Fig. VI.C. - Cat's Skull From Below, Without Lower Jaw, Showing Palatal Surface