CROCODILES AND ALLIGATORS. 



The link next to the tortoise tribe is formed of an important group of reptiles, containing 

 the largest of the reptilian order, larger, indeed, than most present inhabitants of the eaith, 

 if we except one or two African and Indian animals, and some members of the cetaceous tribe. 

 As is the case with nearly all reptiles, they are carnivoroiis, and owing to their great size, 

 strength of muscle, voracity of appetite, and the terrible armature of sharp teeth with which 

 their jaws are supplied, they are the dread of the countries which they inhabit, ruling the 

 rivers with a sway as despotic as is exercised by the lion and tiger on land, the eagle in the air, 

 or the shark in the seas. 



On account of the peculiar manner in which their bodies are covered with square, keeled, 

 bony plates embedded in the skin, and protecting the body with an armor that effectually 

 guards its upper and more exposed portions from any ordinary weapon, they are separated 

 from the true lizards, and scientifically termed Emydosauri, or Tortoise-lizards, the bony 

 plates being considered to have a certain analogy with those of the shielded reptiles. By some 

 zoological authors these animals are termed Loricata, or Mailed Reptiles, from the Latin 

 word lorica, which signilies a coat of mail, or cuirass. 



Although these creatures are capable of walking upon land, for which purpose they are 

 furnished with four legs, they are more fitted for the water than its shores, and are swift and 

 graceful in the one, as they are stiff, awkward, and clumsy on the other. Through the water 

 they urge their course with extraordinary speed, their long, flattened, flexible tail answering 

 the double puiijose of an oar and a rudder ; but on land their bodies are so heavy and their 

 legs are so weak, that they can hardly be said to walk, a term which seems to imply that the 

 body is wholly supported by the legs, but to push or drag themselves along the ground, on 

 which rests a considerable portion of their weight. 



The head of these creatures is always rather elongated, and in some species is lengthened 

 into a narrow and prolonged snout. Each jaw is furnished with a row of sharply-pointed and 

 rather conical teeth. These teeth are hollow, mostly grooved on the surface, and are replaced 

 when they fall by new teeth that grow behind them, and in process of time push the old ones 

 out of their sockets. 



The nostrils are placed at the very extremity of the skull, and upon a slightly raised 

 prominence, so that the animal is able to breathe by merely exposing an inch or so above the 

 water, and thus can conceal itself from almost any foe, or make an unsuspected approach upon 

 its prey. There is yet another more important use for the position of the nostrils. The Croco- 

 diles feed on fishes and various water-loving creatures, but also are in the habit of lurking by 

 the river-bank, and suddenly seizing upon any unfortunate animal that may come to drink. 

 Suppose, for example, that a calf or a dog is thus dragged into the water, the reptile grasps it 

 across the body, and sinks below the surface, so as to keep the head of the victim below water 

 while itself can breathe by means of the elevated nostrils. 



But as during this process the mouth is held widely open, it might be rationally presumed 

 that considerable inconvenience would be caused by the water running down the throat. Siich 

 would indeed be the case, were not this difficulty provided for by a simple yet very wonderful 

 contrivance. At the back of the throat, a pair of thin, cartilaginous plates are so arranged, 

 that when the animal opens its mouth the pressure of the water rushing into the mouth imme- 

 diately closes one upon the other, and effectually prevents the passage of a single drop, the 

 closure being in exact proportion to the volume of water. The structure, indeed, is very like 

 that of the valves of the heart. The channels which lead from the nostrils run very far back 

 through the skull, and open behind the throat-valves, so that respiration is in no way impeded. 

 They cannot, however, swallow their prey while under water, but are obliged to bring it on 

 shore for that purpose. Tlie tongue is small, and fastened down to the lower jaw throughout 

 its length, so that it was formerly thought that the Crocodiles were destitute of that organ. 



