ZOOLOGICAL POSITION AND STRUCTURE ii 



in which it is present to gather their food with the 

 greatest possible rapidity in the open, and then to 

 retire to a less exposed position for the purpose 

 of thoroughly masticating it at leisure. 



True ruminants, in common with camels, llamas, 

 and chevrotains, which also ruminate but are dis- 

 tinguished by various structural peculiarities, and 

 pigs and hippopotamuses, which have not that 

 power, collectively constitute the Artiodactyla or 

 even-toed group of the great order of Ungulata or 

 hoofed animals. As a comparatively full account of 

 the features distinguishing the Artiodactyla or even- 

 toed section from the Perissodactyla or odd-toed 

 section (tapirs, rhinoceroses, and horses) is given in 

 The Ox and Its Kindred,^ it must suffice to mention 

 that whereas in the former the two toes correspond- 

 ing to the third and fourth digits of the human hand 

 and foot are symmetrical to a vertical line between 

 them, in the latter the toe representing the human 

 third digit (which in the modern horse-group is 

 the only one remaining) is symmetrical in itself, 

 and larger than those on its two sides, when these 

 are present. For the distinctive features of the 

 Ungulata or hoofed mammals, the reader may 

 consult the volume already quoted. 



The following table exhibits at a glance the 

 position occupied in the zoological scheme by 



1 In the first four lines of page ii of this work, the terms "even- 

 toed" and " odd-toed " are unfortunately transposed. 



