4 THE HORSE AND ITS RELATIVES 



members of the horse tribe is preferable. Similarly, 

 the name horse, as the denomination of the typical 

 member of the genus Eqzms, is very generally 

 applied to the extinct representatives of the same 

 genus or even of closely allied genera ; and there is 

 less objection to this practice than to the one last 

 mentioned, as there are no vernacular names for the 

 animals in question. The term three-toed horses 

 is, for instance, a convenient one for the members 

 of the extinct genus Hipparion, as it is not likely 

 to lead to confusion. On the other hand, the 

 word horse must have some limitation ; and the 

 American practice of applying it to diminutive 

 ancestral types of the Equidce no larger than foxes 

 is one that is not to be commended. Since the 

 respective meanings of the terms species, genus, 

 family, order, &c., are explained in most works on 

 natural history, it will suffice in this place to state 

 that Equus caballus, as represented by the ordinary 

 domesticated horses of Western Europe, is the 

 typical representative of both the genus Equus 

 and the family Equidcs. Both that family and the 

 BovidcB, or hollow-horned ruminants — of which the 

 ox is the typical member — belong to the great 

 order of hoofed mammals, or Ungulata, so called 

 from the feet of its more typical representatives 

 being encased in solid horny hoofs. 



These more typical groups are divided into two 

 main sections or sub-orders, namely the even-toed 



