750 THE UNGULATES, OR HOOFED MAMMALS 



from the figure of the upper molar tooth of the nylghau given on p. 745, and also 

 from that or the four- horned antelope on p. 748, that these teeth consist of four 

 distinct columns, of which the innermost pair are crescent shaped, with the horns 

 of the crescents turned outwardly. In the lower jaw the molars are narrower, and 

 with a reverse structure; that is to say, the crescents are on the outer side of 

 the tooth, with their horns turned inwardly. Accordingly the name of crescent- 

 toothed (selenodont} Ungulates is applied to all the ruminating members of the 

 group. 



It is important to observe that the true Ruminants are alone characterized by 

 the whole of the four under-mentioned features, viz., no front teeth in the upper 

 jaw, a four-chambered stomach, complete canon bones, and the feet incased in 

 hoofs. Moreover, it is only, in the members of this group that horns are ever 

 met with; these appendages being always arranged as a symmetrical pair (occasion- 

 ally two pairs) on either side of the middle line of the skull. 



The hollow-horned Ruminants, or Bovida, are distinguished from 

 Hollow-Horned,, n . , , r , . 



. their allies by the presence of true horns; that is to say, of hollow 



and unbranched sheaths of horn growing upon bony protuberances, 

 or cores, arising from the frontal bones of the skull, as shown in the figure on 

 p. 749; neither the horny sheaths nor the bony cores being shed at any period of 

 existence. In all existing wild species these horns are present at least in the male 

 sex; but in many domesticated races of cattle, sheep, and goats, they are absent in 

 both sexes; and the same holds good for certain extinct members of the family. 

 Usually the molar teeth of the hollow-horned Ruminants are characterized by the 

 great relative height of their crowns, as shown in the figures of the molar teeth of 

 the nylghau given on p. 745 ; and in all cases there is no tusk or canine tooth in the 

 upper jaw. In some few instances the small lateral toes may be completely 

 absent, but they are generally represented merely by the small spurious hooflets 

 alone, which may be supported internally by minute and irregularly-shaped nodules 

 of bone. 



The hollow-horned Ruminants are chiefly Old-World forms, although they are 

 represented in North America by the musk ox, the American bison, the Rocky 

 mountain goat, and the bighorn sheep. They are quite unknown in the southern 

 half of the New World. 



THE OXEN 

 Genus Bos 



The oxen include the largest and most massively-formed members of the 

 hollow-horned Ruminants, and comprise not only the animals thus commonly desig- 

 nated, but likewise the bisons, yak, and buffaloes. As a rule, they are large and 

 heavily-built animals, with very short and thick necks, and the massive and rela- 

 tively-short head carried nearly in the line of the back; the males generally being 

 provided with a large dewlap, running along the throat from the chin to between 

 the fore-legs. The tail is always long, and is generally thinly haired throughout the 



