THE HOOFED MAMMALS. 233 



THE HOOFED MAMMALS, OR UNGULATES. 

 ORDER UNGULATA. 



The whole of the terrestrial Mammals inhabiting the British 

 Islands which remain for consideration are included in the 

 great Order Ungulata ; a group comprising Oxen, Deer, Pigs, 

 Horses, Tapirs, Rhinoceroses, Elephants, &c. The more 

 typical members of this large assemblage, which alone need be 

 considered in this work, are characterised by having the toes, 

 which never exceed four in number on each foot, encased in 

 horny hoofs, by the absence of collar-bones, and by the cheek- 

 teeth having broad and flattened crowns adapted for masticat- 

 ing vegetable food. While in some forms, like the Pigs, these 

 teeth have short crowns, surmounted by low and comparatively 

 simple tubercles, in others, such as the Oxen and Horses, the 

 crowns become very tall, and have deep infoldings of enamel 

 on the summits, which are more or less completely filled with a 

 softer substance termed " cement." By this means, especially 

 when the tooth becomes worn, a very complicated pattern is 

 produced, the plan of arrangement often taking the form of 

 •our more or less well-defined crescents. 



The typical Ungulates are sub-divided into two main groups, 

 •eadily distinguished by the structure of the foot. In the first 

 )f these, as represented by the Horses and Rhinoceroses, the 

 niddle or third toe (which may be the only one present), is 

 arger than either of the others, and symmetrical in itself, and 

 he members of the group are consequently termed the Odd- 

 oed, or Perissodactyle, Ungulates. Of this group there have 

 )een no existing wild representatives during the historic period 

 n Britain. 



j In the second group, on the other hand, which includes 

 jDxen, Deer, and Pigs, the third and fourth toes (which are 



i 



