268 
FROGS AND TOADS. 
Amphibians are collected in a pond together, the volume ot' sound produced is con¬ 
siderable, and can be heard from long distances, although it is nothing compared to 
that of the bull-frog and many tropical species. Frogs subsist entirely on slugs, 
snails, insects, etc., swallowing large beetles whole, and devouring several at a meal. 
The frog captures its prey by suddenly throwing forwards the tip of its tongue, 
which is invested with a viscid secretion, upon the insect or slug, and then as 
quickly withdrawing it to its normal inverted position. So rapid is the whole 
movement, that it requires a sharp eye to detect it; the insect seeming to disappear 
as if by magic. “Frogs retire,” writes Bell, “ on the approach of winter to their 
hibernating retreats, where they pass the dreary season in a state of absolute 
torpidity. This is generally in the mud at the bottom of the water, where they 
are not only preserved, though at low degree, but also secured from external 
injury. Here they congregate in multitudes, embracing each other so closely as to 
appear almost as one continuous mass. On the return of spring they separate from 
each other, emerge from their places of retirement, and recommence their active 
life by exercising the important function of reproducing their species.” During 
the breeding-season a warty protuberance is developed on the thumb of the male 
to assist in holding the female; and in some foreign species the whole fore-arm 
becomes enlarged at this time. The spawn is deposited at the bottom of the 
water, but soon rises to the surface in the well-known glairy masses; and in due 
season the tadpoles make their appearance. During the tadpole stage frogs are 
devoured in large numbers by newts and the -smaller fishes ; while in the adult 
condition numbers fall a prey to the weasel and pole-cat, the heron and other 
wading birds and the common snake, whose food is almost entirely composed of 
them. Although the common frog is to a large extent aquatic, it is much less so 
than the edible species, which inhabits indiscriminately running or still waters, the 
borders of rivers, rivulets, or streams, lakes or ponds, salt or fresh marshes, or even 
ditches and pools of water. Owing to the presence of the external sacs, the croak¬ 
ing of the male is louder than in the common frog. Both species, like all the more 
typical representatives of the genus, progress on land by means of leaps; while in 
water they swim with the liind-limbs alone. 
Compared to the bull-frog; (A. catesbyancc), of Eastern North 
Bull-Frogs. 1 . ® v an 
America, represented in the figure on p. 259, the European frogs are 
mere dwarfs; but the largest species of all is Guppy’s frog ( R. guppyi), from 
the Solomon Islands, in which the length of the head and body is upwards of 9 
inches. The bull-frog is one of those species in which the tips of the toes are 
pointed, and it is especially characterised by the web extending to the tip of the 
fourth toe of the hind-foot, the large size of the aperture of the ear, and the 
relative length of the hind-leg; the two latter characters distinguishing it from 
Montezuma’s frog ( R. montezumce), of Mexico. The body has no lateral glandular 
fold; and the vocal sacs of the males are internal. In colour the bull-frog is brown 
or olive above, with darker marblings; the under-parts being either uniformly 
coloured, or marbled with brown. In length it measures from 7 to 7| inches, 
exclusive of the legs. More abundant in the southern than in the northern 
portion of its habitat, the bull-frog is generally met with in rivers and streams 
well shaded with trees or bushes, where it may be seen in numbers basking in 
