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. cigilis), 
which belongs to a group distinguished by the greater length of the liind- 
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 fkogs (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. Ihe croaking of the fiog is 
principally uttered during the breeding-season, and when large numbeis of these 
