274 CROCODILES AND SNAKES 



so cause its death in a few short minutes, but must either secure it by 

 strength of jaw alone, or must overcome it by means of sheer bodily 

 strength. Snakes feed upon animals of different kinds, whose bodies 

 would seem far too large to be swallowed whole. But the jawbones 

 are so loosely fastened together that they can be separated to some 

 distance from one another, being then only held together by ligaments. 

 The skin and flesh of the neck, too, can be greatly stretched, and so 

 the snake manages to get the head of its victim fairly into its mouth. 

 By slow degrees it is then worked down the throat by the alternate 

 action of the upper and knver tooth-rows, the jaws separating more and 

 more widely, and the skin of the neck stretching to such a degree that 

 one would think that it nuist certainly burst. At length, after great 

 exertions, the prey is swallowed, the jaws close, and the neck returns 

 to its normal size. 



The Frogs.— There is a group of animals which ])reviously was 

 classed among reptiles, but which, owing to certain differences in 

 their life and structure, are now more properly considered to belong 

 to another class, altogether, under the name of Batrachians. Some of 

 these are familiar to all of us, the toad and the frog, for instance, being 

 very well-known members of the group. 



Now, there is one very important way in wdiich these animals 

 differ from all the reptiles. Crocodiles, turtles, lizards, and snakes are 

 all of exactly the same form when just born as they are when fully 

 mature, the chief difference l)ctween the parents and their young being 

 in point of size. But this is not the case with the frogs, for, when they 

 are first hatched from the ei^g, they are not like their i)arents at all, 

 and do not become so until they have lived for some kttle time in the 

 world. There is, in fact, quite as much difference between the young 

 and the mature frog as there is between a caterpillar and a perfect 

 butterfly. 



During the first part of their lives they live in the water just as 

 fishes do, breathing water instead of air, but in course of time the 

 greater number change their habits altogether, and breathe air itself 

 by means of lungs, just as do all the animals about which we have 

 hitherto read. 



We all of us know the large jelly-like masses which are to be 



