188 



VERTEB&ATES 



some cataract, forming a kind of line, and seizing upon such fish 

 as are forced down by the violence of the stream. In that element 

 they pursue their prey with great swiftness and perseverance ; they 

 swim with much force, and remain at the bottom for thirty or forty 

 minutes Without rising to take breath. They traverse the bottom 

 of the stream, as if walking upon land, and make a terrible devas- 

 tation where they find a great plenty of prey But it oftei 



The Hippopotamna. 



happens that this animal's fishy food is not supplied in sufficient 

 abundance ; it is then forced to come upon land, where it is an 

 awkward and unwieldy stranger ; it moves but slowly, and, as it 

 seldom forsakes the margin of the river, it sinks at every step it 

 takes. If attacked on land, and incapable of vengeance from the 

 swiftness of its enemy, it immediately returns to the river, 

 plunges in head foremost, and a;fter a short time rises to the sur- 

 face, loudly bellowing, either to invite or intimidate the enemy ; 

 but though the Negroes will venture to attack the shark or the 

 crocodile in their natrral element, and there destroy them, they 

 tfre too well appr?e* of the for<je of the Hippopotamus to 

 engage it. 



