482 ZOOLOGY sect. 



does not articulate with the fibula. The premolars and molars 

 are complexly folded, and the posterior premolars usually resemble 

 the molars in size and pattern. The stomach is simple ; the 

 caecum large. There is never a gall-bladder. The teats are 

 situated in the groin, and the placenta is diffuse. 



This sub-order includes the Horses, Asses, and Zebras (Hquidce), 

 the Tapirs (Tapirus), and the Rhinoceroses {Rhinoceros). 



Sub-order b. — Artiodadyla. 



Ungulata vera in which the third and fourth digits of both 

 manus and pes form a symmetrical pair, and in which the others 

 are usually absent or vestigial. The femur has no third trochanter. 

 The tibial surface of the astragalus is flat, the distal surface 

 articulates largely with the cuboid, and the calcaneura has a flat 

 articular surface for the fibula. The premolars are smaller than 

 the molars. The stomach is almost always complex, and the 

 caecum is small. The teats are few and situated in the groin, or 

 numerous and extending along the abdomen. The placenta is 

 diffuse or cotyledonary. 



This sub-order includes the Ruminants — such as the Camels 

 (C'cmnelidce), Oxen(Bovidce),S]xee'p (Ovis), Goa.ts (Ccqjra), Antelopes, 

 Giraffes {Giraffa), and Deer (Cervidai); and the Non-Ruminants, 

 viz., the Pigs {Sios), Peccaries {Bicotyles), and Hippopotami 

 {Hi-ppopotamus). 



Section 2. — Subungulata. 



Ungulata in which the feet may be plantigrade, and there may 

 be five functional digits. The magnum of the carpus does not 

 articulate with the scaphoid, at least in living forms. 



Sub-order a. — Hyrcwoidea. 



Small Subungulata with furry integument, with four completely 

 formed digits in the fore-foot (the pollex being vestigial), and 

 three in the hind-foot (the hallux being absent and the fifth digit 

 vestigial). The ungual phalanges of the four complete digits of 

 the fore-foot are small, somewhat conical and flattened ; that of 

 the second digit of the hind-foot is deeply cleft, and has a long, 

 curved claw; the rest of the digits of the hind-foot have broad 

 nails. There are no canines, and in the upper jaw in the adult 

 there is only a single pair of incisors, which resemble those of the 

 Rodents in their elongated, curved form and in growing from 

 persistent pulps. The thoracic and lumbar vertebrae are very 

 numerous (28-30), twenty-one or twenty-two bearing ribs. The 

 tail is very short. Clavicles are absent. There is a centrale in 

 the carpus. The stomach is divided into two parts by a con- 

 striction. The large intestine has connected with it a pair of large 



