THE AMERICAN BISON 195 



have only three toes to each foot, while the horse, as also 

 the ass, the zebra, and the quagga, has but one. It 

 would be quite a mistake to suppose that the horse's 

 foot consists of a hoof which is not divided ; it con- 

 sists of but a single digit, and the horse's four feet 

 answer to the tips of our two middle fingers and the tips 

 of our two middle toes, and nothing else. The enormous 

 toe which supports the horse contains three bones similar, 

 except as to size and details of form, to those of our own 

 middle finger and toe ; and similarly again, each fore digit 

 is supported by a single middle-hand bone, and each 

 hind digit is supported by a single middle-foot bone, at 

 the top of which are the small bones of the wrist and 

 ankle respectively. Thus, what is commonly called the 

 ''knee" of a horse is truly its wrist, and what is called the 

 " hock " of a horse is really its heel. Though, however, the 

 horse has thus but a single digit and middle-foot bone to 

 each limb, there is, nevertheless, a slender bone on each 

 side of it, though it bears no digit. These two slender 

 bones, called by veterinary surgeons spHnt bones, are the 

 only rudiments of the second and fourth toes. 



Such are the conditions found among existing odd- 

 toed ungulates. With the even-toed group it is other- 

 wise. There are always two toes equally developed and 

 corresponding with our third and fourth toes, and the 

 line of symmetry of the foot passes down between them, 

 instead of along the middle of the third digit, as in the 

 odd- toed hoofed beasts. Two other digits, corresponding 

 with our second and fifth digits, are very often present, 

 but they are always smaller than the third and fourth 

 ones. They are at least so in the hippopotamus. In 

 the swine they do not reach to the ground. 



The only American non-ruminating, even-toed ungu- 

 lates, the peccaries, present two exceptional characters 



