378 



ORDEES OF MAMMALIA. 



the order, though various extinct genera (such as Hyracothr- 

 rium, Hyracodon, &c.) have received names founded on sup- 

 posed likenesses to the existing Hyrax. 



Fig. 660.— Skull of Hyrax. (After Cuvier.) 



Order XL Proboscidea. — The eleventh order of Mammals 

 is that of the Proboscidea, comprising no other living animals 

 except the Elephants, but including also the extinct Mastodon 

 and Deinofhcritfm. 



The order is characterised by the total absence of canine 

 teeth ; the molar teeth are few in member, large, and trans- 

 versely ridged or tuhereulate ; incisors are always present, and 

 grow from persistent pidps, constituting long tusJcs (fig. 661). 

 I7i living Elephants there are two of these tusk-like incisors in 

 the upper Jaw, and- the lower jaw is witliout incisor teeth. In 

 the Deinotherium, this is reversed, there being two tusk-like 

 lower incisors and no upper incisors. In the Mastodons, the 

 incisors are usually developed in the upper jaw, and form 

 tusks, as in the Elephants, but sometimes there are both 

 upper and lower incisors, and both are tusk-like. The nose 

 is prolonged into a cylindrical trunk, movable in every direction, 

 highly sensitive, and terminating in a fiwjer-lilce prehensile lobe 

 (fig. 661). The nostrils are placed at the extremity of the pro- 

 boscis. The feet are furnished with five toes each, but some of 

 the toes may be destitute of hoofs. 



