THE AMERICAN BISON 197 



because they are so big in the dog; and grinding teeth. 

 Of the first there are commonly six above and six below ; 

 of the second, one on each side above and one below ; of 

 the third kind, seven above and seven belo .v on each side. 

 This is the number in the swine, where the eye teeth 

 become tusks, and it is almost the same in the hippopo- 

 tamus and peccaries. The camels and llamas have fewer 

 grinders, and only two cutting teeth in the upper jaw. 

 In all the rest of the ruminants there are no cutting 

 teeth in the upper jaw, which is clothed with a callous pad 

 against which the lower cutting teeth and eye teeth 

 (which are shaped like the cutting teeth) bite. In most 

 ruminants the upper eye teeth are wanting, as well as 

 the upper cutting teeth, the whole front of the upper 

 jaw being absolutely toothless. But in the camels, 

 llamas, arid chevrotains they are present, and in the 

 musk deer, muntjacs, and Chinese water deer they are 

 very large and prominent in the males. Among the odd- 

 toed ungulates the tapirs are toothed, as to number, like 

 the swine. The horse has one grinding tooth less on 

 each side below, while the cutting teeth have an abso- 

 lutely peculiar structure, each having a deep indention 

 or pit on the middle of its cutting surface. This pit, 

 getting filled with particles of food, becomes of a dark 

 colour, and constitutes what is known as the " mark." 

 The presence of this " mark " shows that a horse has not 

 exceeded a certain age, since when the tooth has worn 

 down beyond the extent of the inflection, the "mark" be- 

 comes thereby obliterated. The rhinoceroses have the 

 same number of grinding teeth as swine have, and some- 

 times have no teeth whatever in front of them, though 

 they may have four cutting teeth both above and below. 

 For digestion, every beast possesses a stomach and 

 intestine, and the latter tube has generally projecting 



