560 REPTILIA. 



uninhabitable by the accumulation of putrefying flesh. Perhaps, 

 however, no localities could be pointed out more obnoxious to such 

 a frightful cause of pestilence than the banks of tropical rivers ; 

 those gigantic streams, which, pouring their waters from realm to 

 realm, daily roll down towards the sea the bloated remains of 

 thousands of creatures which taint the atmosphere by their decom- 

 position. 



Such are precisely the situations inhabited, by Crocodiles and 

 Alligators, the largest of the Saurian Reptiles now in existence, 

 animals in every way designed by Nature to feed upon putrefying 

 materials : their tongue (Jig- 252, d) scarcely projects from the 

 lining membrane of the mouth, and its surface (e) is studded with 

 large glands ; the whole interior of the mouth is in fact, from its 

 construction, little adapted to gustation. 



The Crocodile nevertheless likewise kills living prey, which, 

 from the structure of its teeth, it is obliged to effect by dragging 



Fig. 252. 



its victim into the water and there drowning it. This mode of pro- 

 ceeding, however, simple as it might appear, involves many difficul- 

 ties : as the reptile has no other instruments of prehension besides its 

 mouth, and is obliged to hold its struggling prey submersed by 

 the strength of its formidable jaws, it is manifest that, without some 

 special contrivance, the water rushing into the throat of the Cro- 

 codile would prevent it from breathing quite as effectually as the 



