ZOOLOGICALLY speaking, the eat is a mammal belonging to the order Carnivora, or flesh-eaters. Modern classification, based chiefly upon characters drawn from the bony skeleton - which changes slowly with developmental processes through the course of geologic time, and preserves the evidences of common ancestry much longer than the softer parts of the organism - divides the carnivores into three suborders, known as Cynoidea, containing the dogs, wolves, foxes, and jackals; Arctoidea, including bears, racoons, and most of the socalled fur-bearing animals - otters, weasels, skunks, badgers, etc.; and Æluroidea, with four families: Viverridœ - the musk-cats or civets and genets, with the paradoxures and ichneumons; Hyœnidœ - the three species of hyena, with the aardwolf, or Proteles, of South Africa; Cryptoproctidœ, containing but one savage little member, a native of Madagascar, called "foussa"; and finally the cat's own family, the Felidœ.

The degree of perfection reached by any living organism is simply the amount of specialization or adaptation which it has undergone in its relations to the special natural conditions under which its life is passed, and measured by this standard, the cat is the most perfect of carnivores. Feeding upon other animals, which it must pursue with noiseless stealth and capture by an exertion of supreme activity, the cat has padded feet which make no sound in movement; muscles of enormous power and bulk in proportion to its size, and attached to bones addressed to each other at such angles as to form the most complete system of springs and levers for propelling the body known in the whole group; the claws are sharper and curved into strong hooks more than in any other mammal, and by the action of special muscles are withdrawn under the protection of sheathlike pads, that they may escape wear and injury when not in use; no teeth are better fitted for their work - the great canines for tearing, and the scissor-like premolars for shearing off lumps of flesh small enough to swallow; while the short and simple alimentary tract takes up little internal space, and permits of a lithe and slender form suited to the highest activity, at the same time performing its digestive work rapidly, and soon ridding the animal of the burden of the enormous meals which those which feed only when they can are certain to indulge in when the opportunity arises.

In the eye, the fibres of the iris, opening to the widest extent, expand the pupil to a full circle, admitting every ray of light which can fall upon it during the darkness of night, and by a rapid and spontaneous contraction - in some species to a narrow slit, in others to a ring as small as a pinhead - shut off all excess of blinding light at midday, and permit minute exactness of vision under either extreme. Add to all these that the coloring of cats is highly assimilated, as it is termed, or suited to concealment among the various shades of ground and foliage among which it lives - as, for instance, the tiger, buffy yellow, with vertical bars of black, is said to blend perfectly with the upright yellow bamboo stems which stand out against the gloomy interspaces of tropical jungles; and the leopard and jaguar, of a similar yellow, with dark spots and rosettes, living largely in trees, are not readily perceived among the mottling of light and shade resulting from the maze of leaves, boughs, and wandering rays of sunlight; while the cats of one color, like the lion and puma, are of neutral shades of gray or yellow, harmonizing well with earth tints on open plains, and inconspicuous under any surroundings.

It is thus seen that, with all mammals in the field, none probably is so well armed for the battle of life as is the cat.

This general type of structure is common to all cats, such variations as there are, being only in minor characteristics, but slightly related to their life habits. And psychologically, too, there is quite as much uniformity; all cats are carnivorous, preferring to discover and kill their own prey; all are ferocious and sanguinary; loving retirement; moving with concealment and stealth; never affronting danger, but fighting desperately when injured or when escape is no longer possible. All climb with ease, excepting only the tiger and lion, whose bulk has probably deterred them from acquiring the habit. So persistent are the characters both of body and mind in this family, that in spite of thirty-five centuries or more of domestication, the household tabby to-day preserves far more of its ancestral traits than any other of the four-footed associates of man.

Cats are found all over the world, except in the Australian region, Madagascar, and the West Indies. They are mainly tropical and heat-loving, although a few species range far to the north, as the tiger in Asia and the puma in America. The short-tailed lynxes also predominate in northern regions.