554 FAMILY CROCODILID^J; CROCODILES, ALLIGATORS. 



the Lizards ; their bodies being covered with square bony plates, 

 instead of with scales; and the skull having a remarkable 

 solidity. Their general plan of structure, however, is the same 

 as that of the Lizards ; but they are in some respects superior to 

 other Reptiles, their heart possessing four cavities ( 478), 

 and their lungs being more subdivided than those of Reptiles in 

 general. These animals, as is well known, are very ferocious in 

 their disposition ; they seize their prey for the most part in the 

 water, but retire to some retreat on land to devour it ; and they 

 relish it in a state of putrescence. Their aquatic habits are indi- 

 cated by the vertical flattening and expansion of the tail, and by 

 the webbing of the posterior feet ; in this respect, however, there 

 is a difference between the several groups of this family. These 

 animals are only found in warm climates ; and inhabit the rivers, 

 lakes, and marshy places, sometimes swimming out to sea, even 

 to a considerable distance from land. This family is divided 

 into three genera, the Crocodiles, Alligators and Gavials ; which 

 differ in their structure and in their geographical distribution. 

 The true Crocodiles are inhabitants of Africa, India, and the 

 hotter parts of America. Their muzzle is more pointed than 

 that of the Alligators, but much less so than in the Gavials ; 

 the longest teeth in the lower jaw are received into notches on 

 each side of the upper ; the hinder limbs have a ridge of scales 

 along their external border, resembling that which runs along 



FIG. 329. CROCODILE. 



the upper edge of the tail ; and the three outer toes of the hind- 

 feet are entirely webbed. The movements of these animals on 

 land are awkward, the legs being ill formed for running, and 

 the head possessing but little power of motion from side to side ; 

 but in water they dart along with great rapidity, by the lateral 

 movements of the tail, aided by the action of their swimming- 

 feet. The Alligators, or Caymans, are confined to America, and 



