28 



THE HORSE 



both Perissodactyle and Artiodactyle, and the absence 

 of which is the principal distinction between them and 

 the Proboscidea (elephants) and the Hyracoidea. 



The bones of the second row of the carpus no longer 

 stand exactly below the corresponding bones of the first 

 row, but are all shifted a little way to the inner side of 

 the foot, a change which is facilitated by the disappear- 

 ance of the first digit, and which, with certain alterations 

 in the form of the articular surfaces, tends to produce 

 a more perfect interlocking of these bones one with 

 another, and thereby greater stability to the carpal 

 region as a whole (see fig. 1, p. 14). A corresponding 

 change in the tarsus brings the cuboid into articular 

 relation with the astragalus, which it wants in the 

 primitive condition. 



In the number of the digits a considerable modifica- 

 tion has taken place in both feet. In the fore-limbs, 

 instead of five, there are but four toes, a number w T hich 

 was long retained by a considerable section of the order, 

 and persists even to the present day in the one family of 

 tapirs. A foot thus formed may appear at first sight 

 to belong to the Artiodactyle or even-toed type, especially 

 as the missing toe is the first, and the four that remain 

 are exactly those of the Artiodactyles. But on examin- 

 ing a little more closely it will be seen to present all the 

 structural characteristics of the five-toed Perissodactyles, 

 only changed by the removal of the first tee. The third 



