18 
FROG. 
whole water with their legions. They live on the 
leaves of duck-weed and other small water-plants, 
as well as on the various kinds of animalcules, &c. ; 
and when arrived at a larger size, they may even 
be heard to gnaw the edges of the leaves on which 
they feed, their mouths being furnished with ex- 
tremely minute teeth or denticulations. The tad- 
pole is also furnished with a small kind of tubular 
sphincter or sucker beneath the lower jaw, by the 
help of which it hangs at pleasure to the under 
surface of aquatic plants, &c. From this part it 
also occasionally hangs, when very young, by a 
thread of gluten, which it seems to manage in the 
same manner as some of the smaller slugs have been 
observed to practise. Its interior organs differ, if 
closely inspected, from those of the future frog in 
many respects ; the intestines in particular are al- 
ways coiled into a flat spiral, in the manner of a 
cable in miniature. 
“ When the tadpoles have arrived at the age of 
about five or six weeks the hind legs make their 
appearance, gradually increasing in length and 
size ; and in about a fortnight afterwards, or some- 
times later, are succeeded by the fore legs, which 
are indeed formed beneath the skin much sooner, 
and are occasionally protruded and again retracted 
by the animal through a small foramen on each side 
of the breast, and are not completely stretched forth 
till the time just mentioned. The animal now 
bears a kind of ambiguous appearance, partaking 
of the form of a frog and a lizard. The tail at 
