290 



THE VERTEBRATE ANIMALS 



bury themselves in the soft mud of the pond bottom during the 



winter. 



Shortly after the legs appear, the gills begin to be absorbed, and 



lungs take their place. At this time the young animal may be 



seen coming to the surface of the 

 water for air. Changes in the 

 diet of the animal also occur; 

 the long, coiled intestine is trans- 

 formed into a much shorter one. 

 The animal, now insectivorous 

 in its diet, becomes provided 

 with tiny teeth and a mobile 

 tongue, instead of keeping the 

 horny jaws used in scraping off 

 algae. After the tail has been 

 completely absorbed and the legs 

 have become full grown, there is 

 no further structural change, and 

 the metamorphosis is complete. 



The Common Toad. — One of 

 the nearest of the allies of the frog 



is the common toad. The eggs, like those of the frog, are deposited 



in fresh-water ponds, especially small pools. The egg-laying season 



is later than that of the frog. The eggs are laid in strings, as many 



as eleven thousand eggs 



having been laid by a 



single toad. 



Suggestions for Field 

 Work. — The egg-laying 

 season in New York state 

 is early May. At this 

 time procure a female 

 that has not laid her eggs 

 and place her in an aqua- 

 rium. If undisturbed, she 

 may lay her eggs in cap- 

 tivity. Com.pare the bulk 

 of the eggs after they are 

 laid with the size of the The cominon toad. 



Stages in the life of tadpoles of the green 

 frog. The two large tadpoles are in 

 their second summer. Photographed 

 by Overton. 



