110 CLASSIFICATION" OF AMPHIBIANS. 



the lateral compression of the tail^ which thus acts as a 

 large and powerful fin : the tail is no doubt used also as 

 a means of defence, since it is armed with a serrated ridge 

 of strong square scales. The lower jaw is rather longer 

 than the upper, and both are armed with a single row 

 of pointed teeth. The crocodiles are all inhabitants of 

 the rivers and fresh waters of warm countiies, and their 

 mode of feeding is very peculiar. They do not swallow 

 their prey upon seizing it, or is it ever eaten while fresh : 

 the victim is first drowned, and then conveyed to some 

 hole at the edge of the water, where it is suffered to 

 putrify before it is devoured. The recent species 

 are more numerous than was formerly imagined, and 

 they are now arranged under the three genera of Ram- 

 phastoma Wag., Crocodilus Cuv.^ and Cliampsa Wag. 

 The first comprise the Oriental species, having the 

 mouth or muzzle very long and narrow : the second, 

 or true crocodiles, have this part oblong and greatly 

 depressed : while the tliird, or American caymans 



29^^ {fig. 29.).' differ from the 

 last chiefly in having the 

 feet only semipalmated. 

 The true crocodiles are 

 found in both hemispheres, 

 but the caymans are pe- 

 culiar to the New "World. All these agree in certain 

 general characters, which have long induced modern 

 naturalists to keep the three types of the crocodiles distinct 

 from the lizard reptiles, and arrange them not far from 

 the chelonians or tortoises. To these latter^ indeed^ the 

 crocodiles evince a strong affinity in the coverings of 

 their bodies, for both are defended, not by scales like 

 those of the serpents and lizards, but by plates or 

 shields ; with this difference only, that in the one these 

 plates are compactly united at their edges, while in the 

 other they are sufficiently wide apart to admit the 

 free motion of all parts of the body and limbs. The 

 tail of these reptiles is perhaps the most remarkable 

 feature in their structure : it is very long, greatly 



