UNGULA'TA (ante). The order of hoofed quadrupeds is one of the largest of the mammalian division of vertebrate anintals. It comprises three entire old orders, the pachydermata, solidungula, and ruminantia. The pachydermata included the elephant., rhinoceros, hippopotamus. tapit. and the pig, animals having thick skins, and the• name pachyderm is still applied to them as members of the order untrnlata. The ele phant, however, is removed to a senarate order, proboscides. The old order solidun gula included the horse. Mira. and ass, all having solid, or one-toed hoofs. and the; name solidungula still apnIi"s to them as a section of tirtradam. 'I I e c!el fie( r tt n nantia included the ox, sheep, goat, camel, deer, gfraffe, and other animals which chew the cud or ruminate, and have a split hoof, with two functional toes; and the ruminan tia form a group or section of ungulata. As combined in one order the ungulata are characterized as follows: All the four limbs are present, and that portion of the toe which touches the ground is always incased in a greatly expanded nail or hoof. In consequence of the incasement of the toes in hoofs, the limbs have no prehensile func tion, and are entirely subservient to locomotion; consequently, clavicles are wanting in the entire order. There are two sets of enameled teeth; the molars are massive, and have broad crowns, adapted for grinding vegetable substances.
The order is divided into two primary sections according to the number of toes; the perissodactyla, in which the toes or hoofs are odd in number, and the artiodactyla, in which they are even. The section perissodactyla includes the rhinoceros, tapir, horse, and its allies, and some extinct forms, all having the following characteristics; hind feet odd-toed, and also the fore-feet, except in the tapirs and brontotheridm. The dorso lumbar vertebrae are never less than 22 in number, and the femur has a third trochan ter; horns, when present, not paired (except in brontotheridm and diceratberium). There is usually only one horn, but when there are two, one is placed behind the other in the middle line, and in no case are they supported by horn cores. Stomach simple,
and there is a large cwcum. The three groups of perissodactyle ungulates, the horses, the tapirs, and the rhinoceroses, are widely separated in many important characteris tics, but the intervals are filled by an extensive series of fossil forms, which commence in the lower tertiary strata. The perissodactyle section includes the following seven families: Fan. 1. Coryphod,ontidce (Marsh) comprising a number of tapir-like animals found in the eocene; skull without horns, and with small nasal bones; brain 3 remark 3 ably small; dental formula; i 3-3, 1-1 pm, 4 m 3— The canines are not 3-3 molars of tapiroid type, having two transverse ridges. Limbs short, both fore and hind feet furnished with five complete toes, all having hoofs. Fam. 2. ceroticice, including only one genus, rhinoceros (q.v.). Fam. 3. 'Tapirida, see TAPIR, ante. Pam. 4. Brontotheridce, large fossil mammals, found by prof. Marsh in the miocene of North America, having in the fore feet four nearly equal toes, and in the hind feet three, thus resembling the tapirs. See TETANOTHERIUM, Fam. 5. Palceotherida, in cluding extinct ungulates from eocene and miocene, and characterized by having three toes to all the feet, canine teeth, and with the lower molars having a double-crescentic See PALEOTKERIUM, ante. Fam. 6. Macrauchenida, comprising the single genus macrauchenia, from the late tertiary deposits of South America. These animals were of large size, having three-toed feet, and, a third femoral trochanter, and with cervical vertebrae like those of the camels. General form of skull, equine, and the incisors have 3-3 1-1 5 3a corona] pit; diastema small; dental formula: i 3— 3 ' — • c 1-1; -- • pm m = 46. Fam. 7. Solidungula or equida This family comprises the horse (q.v.), the ass (q.v.), and the zebra (q.v.). See also HORSE, Fossn.. The family equicice is divided by Dr. Gray into two genera, equus, .comprising the horse. and asinvs, comprising the asses and zebras. Many authorities, however, place all the forms under the single genus equus.