TYPICAL FROGS. 



267 



pointed, in place of obtuse, muzzle. The coloration is very similar to that of the 

 common species, but there is sometimes (as in the right-hand figure of the illustra- 

 tion), a light stripe bordered by two black ones down the middle of the back, while 

 the under-parts are uniform. A third European species is the agile frog (R. agilis), 

 which belongs to a group distinguished by the greater length of the hind- 

 limbs ; the whole form being slender, and the muzzle pointed. Its general colour is 

 greyish brown, with dark spots ; the temporal spot being dark and distinct, with a 

 light line running from its extremity to the snout, while the hind-limbs are 

 regularly barred, and the under-parts unspotted. Two other European species, the 



agile frogs (nat. size). 



one (R. iberica) from Spain and Portugal, and the other (R. latastei) from the 

 neighbourhood of Milan, differ by the spotted lower surface of the body. Even the 

 tadpoles of the whole of these more or less nearly allied species present differences 

 by which they can be distinguished from one another. 



The common frog, whose habits may be taken as typical of the allied members 

 of the genus, is found in most parts of Europe, where there is a sufficiency of 

 moisture and shelter for its existence ; the presence of water being essential during 

 the breeding-season. All are probably familiar with the manner in which a frog 

 swallows air; but it is perhaps less generally known that if the mouth of one of 

 these creatures be kept forcibly open, death must inevitably ensue, owing to the 

 impossibility of breathing while in this state. The croaking of the frog is 

 principally uttered during the breeding-season; and when large numbers of these 



