ANOPLOTHE'RIUM (from the Greek a, privative; (7t)opion, armor; and therion, a beast), a genus of extinct pachydermatous quadrupeds (see PACIIYDERMATA), established by envier from bones occurring in great abundance in the gypsum strata of the upper eocene (q.v.) formation, near Paris. They are found also in the same formation in the isle of Wight and elsewhere. The teeth differ from those of all other pachydermata, extinct or recent. There are six incisors, two canines, eight premolars, and six molars in each jaw—the dental formula thus agreeing with that of the fossil genus pakeotheriuna (q.v.); but the teeth are arranged in a continuous series without intervening vacancies— a circumstance very remarkable, as it does not occur in any existing quadruped, but now appears in man alone. The molars of the upper jaw are quadrangular, those of the lower marked with a double or triple crescent of enamel, which forms prominent ridges. In some respects the teeth resemble those of the ruminantia (q.v.), or ruminating quad rupeds, between which and the pachydermata the A. has been thought to form a connect ing link; but in some of the species originally included in this genus, and which arc now sometimes ranked along with it under the name anoplotheroids, the teeth exhibit peculiarities which have led to the supposition that their food may not have been exclusively vegetable. . The snout is not much elongated, and it is evident that there
was no proboscis. The feet are terminated by two toes, as in the ruminantia; but they have always separate metacarpal and metatarsal bones, not a single canon bone. A con siderable number of species of A. and of anoplotheroids have been determined, differing in size from that of a small ass to that of a hare, or even of a guinea-pig; so that the smallest species must have been smaller than any hoofed quadruped now existing, or any known to have ever existed. They differ also considerably in general appearance, some having had comparatively long limbs and a light and graceful form, whilst some were firmly built and heavy. Their habits may be supposed to have differed accordingly. The true anoplotheria were probably very similar in habits to tapirs. The powerful flattened tails of some are supposed to indicate an adaptation for aquatic life; others have smaller supplemental toes, besides the two hoofs. They form the genera dickodon, dichobune, ziphodon, and microtherium.