UNGULATA. 423 



CHAPTER XXXVIII. 



ORDERS OF MAMMALIA Continued. 



ORDER VI. UNGULATA. The order of the Ungulata, or 

 Hoofed Quadrupeds, is one of the largest and most important 

 of all the divisions of the Mammalia. It comprises three 

 entire old orders namely, the Pachydermata, Solidungula, and 

 Ruminantia. 



The first of these old divisions that of the Pachydermata 

 included the Elephants, Rhinoceros, Hippopotamus, Tapirs, 

 and the Pigs, all characterised, as the name implies, by then- 

 thick integuments. The name is still used to express this fact, 

 though the order is now abandoned, and is merged with that 

 of the Ungulata; the Elephants alone being removed to a 

 separate order under the name of Probosddea. 



The second old order that of the Solidungula or Solipedes 

 included the Horse, Zebra, and Ass, all characterised by the 

 fact that the foot terminates in a single toe, encased in an 

 expanded hoof. The name Solidungula is still retained for 

 these animals, as a section of the Ungulata. 



The third old order that of the Ruminantia includes all 

 those animals, such as Oxen, Sheep, Goats, Camels, Giraffes, 

 Deer, and others, which chew the cud or " ruminate," and have 

 two functional toes to each foot, encased in hoofs. The name 

 Ruminantia is still retained for these animals, as constituting 

 a most natural group of the Ungulata. 



All these various animals, then, are now grouped together 

 into the single order of the Ungulata, or Hoofed Quadrupeds, 

 and the following are the characters of the order : 



All the four limbs are present, and that portion of the toe 

 which touches the ground is always encased in a greatly-ex- 

 panded nail, constituting a "hoof." There are never more 

 than four full-sized toes to each limb. Owing to the encase- 

 ment of the toes in hoofs, the limbs are useless for prehension, 

 and only subserve locomotion ; hence clavicles are always want- 

 ing in the entire order. There are always two sets of enamelled 

 teeth, so that the animal is diphyodont. The molar teeth are 

 massive and have broad crowns, adapted for grinding vegetable 

 substances. 



The order Ungulata is divided into two primary sections : 

 the Perissodactyla, in which the toes or hoofs are odd in num- 

 ber (one or three), and the Artiodactyla, in which the toes are 

 even in number (two or four). 



