92 



BEPTILESKBATIIACHIANS DIAGRAM 5 



it is from this peculiarity that the 

 snake derives its name. 



All serpents, like lizards, have a 

 forked tongue which they sometimes 

 End of taH of rattlesnake, dart out, and which is sometimes 

 improperly called their sting ; but it is soft, and it is quite im- 

 possible for them to do any harm with it. One ought always 

 to destroy as many vipers as possible in a country, but there 

 is no occasion to destroy the common snakes. Vipers, unlike 

 most snakes, do not lay eggs, but bring forth their young alive. 



BATKACHIANS, DIAGBAM 5. 



The name of this family is derived from a Greek word mean- 

 ing frog ; and it also includes the salamanders. All these ani- 

 mals much resemble other reptiles, but they differ from them in 

 having no scales, but a naked skin, and especially because they 

 come out of the egg in a different form from that which they will 

 afterwards assume ; they thus undergo what is called a metamor. 

 phosis. A. frog, for instance, lays eggs. The eggs are trans- 

 parent as jelly, and* we soon see the vitellus (which is not yellow 



as in the fowl, but brown) transformed 

 into an animal which has 110 re- 

 semblance to a frog ; it is composed of 

 a large head and a tail, and is called 

 a tadpole. It has two tufts on each 

 side which are gills, and it has no 

 lungs. It does not breathe the air of 

 the atmosphere. But there is always 

 a certain quantity of air in water ; and 

 this is what forms small bubbles on 

 the sides of a vessel in which water is 



Tadpole. 



