22 STOEY OF THE AMPHIBIANS 



in the spring when in concert with others it takes on 

 various forms of squawks, croaks, etc., which may 

 " make night hideous." 



Frogs evidently sing in concert — even different 

 kinds chiming in with others, as any one may ob- 

 serve ; and among the bullfrogs there are leaders of 

 the groups of singerfe, which seem to start first and 

 thus get the whole band into pulsations or throbs of 

 sound. In some tropical regions there is really a 

 musical harmony in these concerts, and they are 

 rather pleasant to human ears. It is known that 

 some birds sing in harmony — the one making a 

 good "second" to the other. But in many other 

 cases the noise of frogs in the Tropics is so great 

 that nervous persons sometimes have to leave the 

 region. 



As a rule amphibians do not cry out in fright, 

 though our spring-frog (or green frog) is noted as 

 an exception. Rarely do they express any sound in 

 distress. A few groan under suffering, but usually 

 they go silently to their doom, even while being swal- 

 lowed alive by a snake. Neither do they as a rule 

 express rage by sound. Dr. Lydekker, however, 

 notes that the horned frog of South America (Fig. 

 10) — the one that has been noted aS vicious and poi- 

 sonous — defies its foes with a sort of bark, but that 

 it has a clear bell-like tone for its friends. Perhaps 

 then here low down in the backboned folk the lan- 

 guage of rage is first separated from the language of 

 love. Some of the fishes, however, had been calling 

 for mates before this, for the heai^ is older than the 



