124 NATURE STUDY 



They each have four toes, which correspond to our four 

 fingers. The hind legs are live toed and webbed. 



The male has a vocal sac, by means of which, particu- 

 larly in the spring, he gives his loye croak. The tongue 

 in both sexes is two forked, and attached to the middle 

 part of the jaw by its forward end. 



The eggs of a toad occur in strings. The toad tadpole 

 is black, much smaller, and develops more quickly into 

 the adult form than the tadpole of the frog. 



Method : 



Is the tadpole a fish ? Why ? 



So far as appearances go, there are good arguments, to 

 the mind of the child, on both sides. The mental disci- 

 pline involved in weighing the evidence and settling the 

 question is very valuable, particularly when he is subse- 

 quently required to state sharply and clearly the resem- 

 blances and differences between the embryonic frog and 

 the adult fish. If children have already witnessed the 

 metamorphosis of the tadpole, review the facts with indi- 

 vidual drawings. Otherwise, wait until spring, when this 

 wonderful change is sure to occur in the schoolroom. 



Snail. 

 Facts : 



Observe in the living animal the brown skin with the 

 limy shell underneath. The sutures, the whorls, the 

 spire, the apex, the body whorl, the lines of growth, 

 the mouth, the operculum, the foot, the eyes, the tenta- 

 cles, the mantle, are all shown in the drawings. 



Limnea is an example of a lung-breathing pond snail, 

 and, like other lung breathers, keeps the surface of the 

 water clean. The snail ascends at fairly regular inter- 



