280 UNGULATA 



hair on the lips, on the sides of the head and neck, and at the 

 extremity of the short compressed tail, the skin of the hippopotamus, 

 some portions of which are two inches in thickness, is entirely desti- 

 tute of covering. 



The common Hippopotamus (H. amphibius), widely distributed 

 in the rivers and lakes of the African continent, is a huge bulky 

 animal, characterised by having only two incisors on either side 

 of each jaw ; the central lower pair being very much larger than the 

 outer ones. A male from the Upper Nile which lived for nearly 

 thirty years in the gardens of the Zoological Society of London 

 measured 1 2 feet along the back from the nose to the root of the tail. 



The Hippopotamus lives in herds of from twenty to forty 

 individuals on the banks and in the beds of rivers, in the neighbour- 

 hood of which it finds its food. This consists chiefly of grass and 

 aquatic plants, of which it consumes enormous quantities, the 

 stomach being capable of containing from 5 to 6 bushels. These 

 animals feed principally by night, remaining in the water during the 

 day, although in districts where they are undisturbed by man they 

 are less exclusively aquatic. In such regions they put their heads 

 boldly out of the water to blow, but when rendered suspicious by 

 persecution, they become exceedingly cautious, only exposing their 

 eyes and nostrils above the water, and even this they prefer 

 doing amid the shelter of water plants. In spite of their enormous 

 size and uncouth form, they are expert swimmers and divers, and 

 can remain under the water from five to eight minutes. They 

 are said to walk with considerable rapidity on the bottoms of 

 rivers, beneath at least a foot of water. At nightfall they come 

 on land to feed ; and when, as often happens on the banks of 

 the Nile, they reach cultivated ground, they do immense damage 

 to growing crops, destroying by their ponderous tread even more 

 than they devour. 



A much smaller species, known as the Pigmy Hippopotamus 

 (H. liberiensis), inhabits some of the rivers of Western Africa, and 

 is characterised by having only a single pair of lower incisors. 

 Mainly on this account, it has been proposed to regard this species 

 as representing a distinct genus, under the name of Chceropsis ; but 

 since it agrees so essentially in other characters with the common 

 form, and sometimes has two incisors on one side of the lower 

 jaw, it appears preferable to include it in the type genus. The 

 greater relative size of the brain-cavity as compared with the facial 

 portion of the skull renders, indeed, the contour of the skull 

 decidedly different from that of H. amphibius ; but this is a feature 

 generally found in young individuals of larger species, and also in 

 the adults of allied smaller forms. 



Both the existing species are now exclusively confined to Africa, 

 but in the Pleistocene and Pliocene periods the genus was widely 



