The following account of the process of rumination is an abbreviation of that given by T. H. Huxley in his Anatomy of V ertebrated Animals. A ruminant does not masticate its food on first taking it into its mouth but swallows it hastily, well mixed with saliva. Only when its appetite is satisfied does it stop grazing and seek a place of safety where it can lie down and "chew the cud" at leisure. If we closely observe a cow which has just lain down in a field after a period of grazing, its body inclined to one side, we notice that after an interval of quiescence a sudden spasm, rather resembling a hiccough, passes over the animal's flanks, and that at the same time something is quickly forced up the gullet into the mouth. This is a bolus of grass which, rendered sodden by the fluids in the stomach, is now returned to be masticated by the grinding teeth. This process is repeated until most of the grass which was originally cropped has been reduced to pulp. A ruminant's stomach is divided into four compartments. When the food is first hastily swallowed it passes no further than the first and second of these. On second swallow ing it passes along a groove in the roof of the second, directly into the third compartment ; chemical digestion takes place in the fourth compartment, which alone has gastric glands in its walls for secretion of digestive juices.
There are four main types of horn construction among the Pecora : (I) The antlers of deer. These are usually found in the male deer only, but in the reindeer they are present in both sexes. They grow out from the frontal bones of the skull as solid processes which rapidly reach their full size. At first they are cov ered by soft and hairy skin. Then a circular ridge called the burr appears at a short distance from the base of the antler and divides the latter into pedicel, on the skull side of the burr, and beam, on the far side. The circulation in the beam now gradually dwindles, and the skin dies and peels off, leaving exposed the dead bone beneath it. Absorption and sloughing take place at the extremity of the pedicel, beam and burr are shed, and the end of the pedicel scabs over. Fresh skin gradually grows up under the scab, so that the pedicel becomes once more smooth and hairy.
The antlers are shed and grown anew every year, usually adding additional branches each time. See DEER.
In the bovine ruminants the bony core formed by the frontal bone is covered by a horny sheath. The core itself is hollow, instead of solid as in the deer, and therefore the Pecora in this group are sometimes termed the "hollow-horned ruminants" or Cavicornia. The horny sheath is never shed but persists throughout life and grows with the growth of the core. This type of horn is never branched but may be curved, spirally twisted, or compressed ; it is often present in both sexes. See SHEEP, GOAT, ANTELOPE, etc. (3) In the giraffes (q.v.) the horn-cores are cov ered with soft and hairy skin and are never shed. (4) In the North American pronghorn, Antilocapra, there is a permanent, unbranched horn-core enclosed in a horny sheath as in the Bovi dae, but this sheath is forked, and furthermore is shed yearly after the rutting season owing to the development of a new sheath which pushes the old one off. See PRONGHORN.
These four types of horn are characteristic of the four families into which existing Pecora are classified: the Cervidae or deer, the Giraffidae or giraffe and okapi, the Bovidae or oxen, sheep, goats, antelopes, etc., and the Antilocapridae, solely represented by the North American pronghorn. Many other forms, now ex tinct, are known as fossils. The earliest of these were small forms with no antlers but a pair of long slender tusks in the upper jaw like those of the musk deer. From such as these were derived not only the modern families but several families now quite ex tinct. Especially noteworthy among these latter are the Meryco dontidae and the Sivatheriidae. Merycodus was a small North American Miocene form with a pair of simple forked antlers very like those of primitive deer but apparently never shed; many characteristics in the skeleton suggest relationship to Antilocapra.
Sivatherium of the Indian Pliocene, allied to the giraffes, was a gigantic animal with a pair of large palmate antler-like outgrowths on top of the skull and a smaller conical pair above the orbits.
that for ARTIODACTYLA. (H. S. P.)