436 | ZOOLOGY. 
body, very short legs, the belly reaching nearly to the ground; by an enor- 
mous head terminated by a broad muzzle. The tail is short; the ears and 
eyes small. There are to each foot four nearly equal toes terminated by 
little hoofs. These animals frequent rivers, and feed upon roots and other 
vegetables. They are stupid and ferocious. The HA. amphibius from 
southern Africa is represented on pl. 111, jig. 8. Hippopotami were 
formerly found throughout Egypt, very abundantly in the Nile, but are con- 
fined now to Nubia and to the rivers of central and southern Africa, in 
Senegal, Zaira, and Gambia. During daytime they keep in the rivers, 
hidden among marshy grasses. They are good swimmers, and can remain 
immersed a very long time. When swimming they snort heavily, and 
exhibit only the snout above the water. They are often met with in flocks 
of fifty individuals or more. They sleep and lie exposed to the sun in 
shallow water. The female produces only one young at a time. Hippopo- 
tami are not dangerous to man, unless attacked by him and wounded. 
They are killed either by the musket or the harpoon. The Africans make 
use of the fat and tongue as food, the skin for whips, and the canines (some- 
times two feet in length) are worked in the same way as the tusk of the 
elephant, and seem to be a finer article. A small species, H. hberiensis, 
is found in the rivers of Liberia, where it is rather common. Fossil species 
of Hippopotamus are quite numerous in Asia, less so in Kurope. Their 
discovery in. America is quite recent. Where they possess only four 
incisors they form the genus Tetraprotodon, and when six Incisors exist in 
both jaws we have the genus Hexaprotodon. The species with six incisors 
in both jaws are more numerous than the others. 
The genus Potamohippus is extinct and little known. It has been esta- 
blished upon some teeth from the tertiary beds of Germany, resembling 
much the upper canines of the Hippopotamus, or the lower milk internal 
incisor of the same animals, but with the difference of being deprived of a 
furrow at their inner surface. 
The genus Srderothervwm was created from a fragment of an upper 
grinding tooth from the tertiary of Wirtemberg, whose surface is some- 
what like that of Hippopotamus. | 
The genus “Ylasmothertwm was established upon a fragment of the lower 
jaw, and said to have come from Siberia. Since then one tooth was dis- 
covered near the Caspian Sea, and a posterior part of a head found on the 
Rhine has also been referred to it. The molar teeth remind us of those of 
the rhinoceros; but the enamelled plate of the interior is more undulated, 
and presents nearly the same complication as in the teeth of the horse, and 
perhaps still more that in Hippotherium, or horses of the tertiary era, 
which sometimes undulate. Their elongated and prismatic form constitutes 
another analogy with the teeth of the horse. The form of the jaw itself, 
its size and thickness, indicate a stout animal resembling probably the 
rhinoceros. in its general outlines, and reaching the bulk of the largest 
species of this genus. Its habits were probably also similar to those of the 
rhinoceros. 
Fam. 8. RaInocEROTIDZ. The genus Rhinoceros is easily distinguished 
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