NOTE-BOOK OF A NATURALIST. 177 



presence of an orbicular sphincter with a protrusive 

 power, so that the air can be taken in with the least 

 possible exposure of the head. 



These two portions of its animal machinery are of the 

 greatest consequence to the well-being and safety of an 

 animal that spends so much of its time in the water. 

 The beautifully-contrived eye is unlike that of any mam- 

 miferous quadruped known to me. It approaches, in its 

 power of rolling round when it is in a state of protru- 

 sion, to that of the chameleon, and, like it, must command 

 a very extensive area. See how admirably this is fitted 

 to the requirements of the animal. If danger threatens, 

 the hippopotamus instinctively rushes to the river ; and, 

 while there latent, can manage to just lift his head 

 among the water plants, and roll his eye, ' like the bull 

 in Cox's museum,' but to much better purpose. If all is 

 safe, and according to his observation he may turn out, 

 he can quit his subaqueous retreat ; or, if all be not 

 right, he can quietly sink again and remain in his cool and 

 unapproachable retreat at the bottom, occasionally rising 

 and protruding his muzzle only for the necessary air- 

 supply, and then down again. Thus, if the animal be 

 on its guard, presenting no mark for a rifle, even if the 

 hand that bore it could ' hand out ' like that of the 

 Master of Raveuswood.* 



* Take the evidence of one wlio would have struck the dollar 

 from between the finger and thumb of the keeper, as cleverly as 

 ever Edgar could have done the feat. 



' Seleka had sent men do\\-u the river to seek sea-cows' — the 

 name by which the hippopotami are known to the colonists — 

 ' and they soon came running after me to say that they had found 

 some. I accordingly followed them to the river, where, in a long, 

 broad, and deep bend, were four hippopotami, two full-grown 

 cows, a small cow, and a calf. At the tail of this pool was a 

 strong and rapid stream, which thundered along, in Highland 

 fashion, over large masses of dark rock. 



' On coming to the shady bank, I could at first see only one 



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