22 



THE COMMON FROG- 



[chap. 



found in England as well as on the Continent of 

 Europe. It is as widely distributed over the Old 

 World as is R. temporaria, but it is unknown in 

 America. It is easily to be discriminated from the 

 common species by the absence of that dark, sub- 

 triangular patch which extends backwards from the 

 eye in R. teniporaria. 



Fig. 4. — The Edible Frog {Rcna esculenta). 



A 



\ 



The male of R. esculenta is further to be distin- 

 guished from the male of the common Frog by the 

 fact of its having the floor of the mouth, on each side, 

 distensible as a pouch — the pouches, when distended, 

 standing out on each side of the head. These pouches 

 are called ** vocal sacs," and no doubt aid in inten- 

 sifying these animals' croak, which is so powerful 

 that (on account of it and because of the country 

 where they are common) they have been nick- 

 named *' Cambridgeshire Nightingales." Specimens 



