THE VERTEBRATES 425 



The tadpoles of both the tailed and tailless forms of Am- 

 phibia are similar ; but, as already described in 61, the tails 

 of frogs and toads are absorbed while legs are developing and 

 the tadpoles are metamorphosing into the adult state. The 

 loss of the tail, and the fuller development of lung-breathing 

 adapts frogs and toads to living on land. Toads are still 

 better adapted by their hard and dry skin, which enables 

 them to live in places so dry that frogs would perish because 

 their skin must be kept moist. 



In geology the Amphibians are noteworthy because 

 certain salamander-like forms were the first five-toed verte- 

 brates. The remains of these ancient amphibians have been 

 found in the earliest coal beds (Carboniferous Age). The 

 present-day types of amphibians have not been found until 

 late in geological history (Eocene times). 



The name Amphibia means "both kinds of life," referring 

 to the fact that these animals are both aquatic and terrestrial. 



350. Myths Concerning Amphibians. The skin secre- 

 tion in some toads is disagreeable or even poisonous to their 

 enemies; but produces no serious effect on human skin. 

 Warts on small boys' hands are not caused by handling 

 toads. The truth is that warts may be caused by slight 

 scratches which allow dirt to get into the skin. Moreover, 

 killing a toad will not " cause your father's cow to give 

 bloody milk," for a moment's serious thought shows us the 

 absurdity of the folklore that there is such a relation between 

 cows and toads. Both the wart and the milk legends are 

 absolutely unscientific. There are numerous other absurd 

 beliefs concerning common animals, and one who has read a 

 modern textbook on animals will always demand proof or 

 the authority of some modern scientific book before accept- 

 ing them. 



351. Economic Relations of Amphibia. It is well known 

 that frogs' legs are eaten; and it has proved profitable to 

 catch frogs for the market. In fact, the annual hunting of 



