Ungulata. 313 



the first of which the food is temporarily received 

 until it is regurgitated into the mouth, when it is com- 

 pletely masticated, and afterwards conveyed to the true 

 digesting stomach. This process is known as the func- 

 tion of ' chewing-the-cud, ' •or ruminating ; and the Un- 

 gulates in which it occurs are consequently termed Rumi- 

 nants. The ruminating function is, however, developed 

 in the camels and chevrotains, as well as in the assemblage 

 of four families constituting the present group; but as 

 the camels and chevrotains differ in several important re- 

 spects, it is convenient to designate the group under con- 

 sideration as the true Ruminants, or technically, the 

 Pecora. 



"The Hollow Horned Ruminants are distinguished 

 from 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, 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 cat- 

 tle, sheep and goats, they are absent in both sexes ; and the 

 same holds good for certain extinct members of the fam- 

 ily. Usually the molar teeth of the Hollow Horned Rumi- 

 nants are characterized by the great relative height of 

 their crowns; 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 gen- 

 erally 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 Big Horn Sheep. They are quite unknown in 

 the southern half of the New World." 



