CONCERNING TADPOLES 191 



as is shown in our illustration. With the fin which sur- 

 rounds it this tail is just four inches deep. 



Having attained its maximum, it begins slowly to decrease 

 in size. A tadpole in the British Museum in which the 

 hind legs measure three inches in length has a total length 

 of seven inches. By the time that it is ready to leave 

 the water, the body has shrunk to an inch and a half 

 long, and the tail to two inches — a mere shadow of its 

 former self. What interpretation is to be placed on this 

 marvellous history ? So far no one seems to have at- 

 tempted the task of answering this question. But it seems 

 to indicate either some special provision to meet peculiar 

 external conditions, or a provision to enable the animal 

 to tide over an unusually prolonged fast pending the re- 

 modelling of the jaws and intestines, such as we have 

 already described in the common frog, wherein it will be 

 remembered the tail serves as a source of food-supply 

 during the fast. 



That the Amphibia display a very remarkable abiUty 

 to maintain existence under adverse conditions, the fore- 

 going instances surely amply demonstrate. And the 

 following cases further illustrate the versatility of this 

 group of animals, whereby they have been enabled to 

 occupy odd corners in Nature's garden which otherwise 

 would have been closed to them. 



This departure from what we may call the normal train 

 of events can be traced through many gradations, some of 

 the more striking of which are now to be considered. One 

 of the simplest cases is that furnished by a large tree-frog 

 (Hyla faber) known in Brazil as the " Ferreiro " — ;" the 

 smith " — from its extraordinary voice, which sounds hke 

 a mallet slowly and regularly struck upon a metal plate. 

 This frog actually builds a nursery in the shallow water 



