NATURAL HISTORY . 163 



" Man hath hi.- daily woi-k of body or mind, 

 And the reu^rd of heaven on all his ways ; 

 While other animals inactive range, 

 And of their H.oiugs God takes no account." MIT/TOW. 



before the form of the animal was well-known. Being generally 

 seen in the water, with its ears, eyes, and nostrils only emerging 

 therefrom, it is found that the partial profile thus afforded, 

 presents a considerable resemblance to the head of a horse ; and 

 hence the popular idea. 



458. How are the eyes and nostrils of the hippopotamus 

 adapted in their structure and position to the habits of the 

 animal ? 



It is necessary that the muscles of the eye should be powerful, 

 endowed with great versatility, and capable of protruding or 

 withdrawing the eyeball, which can be either projected remarkably, 

 or sunk within the orbit considerably, so as to adapt it -for vision 

 in the different media where it is to act, whether the animal be on 

 land, just under water, or far down beneath its surface. The 

 nostrils, which are so placed that they just appear above the 

 surface of the water, when the animal rises from below, can be 

 closed when the animal descends into the deep, and opened when it 

 comes up to take in a supply of air. 



459. These two portions of the animal machinery of the hippopotamus are of the 

 greatest consequence to the well-being and safety of a creature that spends so 

 much of its time in the water. The beautifully contrived eye has the power O- 

 roiling round when it is ir a state of protrusion, and is admirably adapted for the 

 requirements of the animal. If danger threatens, the hippopotamus instinctively 

 rushes to the river ; and while there hidden can manage to just lift its head among 

 the water plants and take his observation. If all is safe, he can quit his retreat, or 

 if all be not right he can quietly sink 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. 



4CO. Wliy is the rhinoceros so called ? 



From a Greek word signifying nose-horn, in reference to the 

 horny projection upon the snout, which is a characteristic of these 

 animals. The rhinoceros unicornis has one horn, and the 

 bicomis has two. 



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