BREEDING HABITS OF FROGS AND TOADS 365 



when the young frogs are ready to make their appearance 

 in the world. 



Perhaps, however, the most pecuHar kind of " nursery " 

 is the one found in Darwin's frog {Rhinoderma darivmt). 

 In this extraordinary creature the males are provided in 

 the breeding season with an enormous pouch on the throat, 

 in which the large eggs (generally about ten in number) 

 are hatched and the tadpoles protected until they become 

 true frogs. The tadpoles never have external gills, and 

 probably not internal ones either, so that they are much 

 more advanced at birth than is the case with their brethren 

 of ordinary species. 



Another instance of abbreviated or accelerated develop- 

 ment is furnished by Goeldi's tree-frog {Hyla goeldti) of 

 Brazil. Here the score or so of eggs are carried on the 

 back of the female, in which the skin of the margins is 

 raised so as to form a kind of saucer. According to one 

 authority, the newly hatched young are in the form of 

 perfect frogs, which prefer not to stay in water. Another 

 method of carrying the eggs is displayed by a Cingalese 

 frog {Rhacophorus reticulatus), in which they adhere to the 

 abdomen of the female. 



Some frogs, again, such as Spea hammondi of North 

 America, are in the habit of depositing their spawn in 

 rain-pools liable to rapid desiccation. And in these cases 

 the tadpoles acquire limbs at an unusually early age, in 

 order to be enabled to seek a fresh pool when their own 

 shows signs of giving out. The tadpoles of an Idaho 

 frog {Spea bombifrons) show a singular dislike to water, 

 even while in the swimming stage of existence ; they 

 breathe air, and live on the bare ground in smooth spaces 

 which they clear for themselves. Three other American 

 species (two of which belong to the genus Dendrobates, 



