RANA. 
imbedded the embryo, or tadpole, in lire 
form of a round black globule. 1 he spawn 
commonly lies more than a month, or some- 
times five weeks, before the larva* or tadpoles 
are hatched from it ; and during this period 
each egg gradually enlarges in size, and a few 
days before the time of exclusion the young 
animals may be perceived to move about in 
the surrounding gluten. When first hatched, 
they feed on the remains of the gluten in 
which they were imbedded ; and in the space 
of a few days, if narrowly examined, they will 
be found to be furnished, on each side the 
head, with a pair of ramified branchiae or 
temporary organs, which again disappear 
after a certain space. These tadpoles are so 
perfectly unlike the animals in their complete 
fciate, that a person not conversant in natural 
history would hardly suppose them to bear 
any relationship to the frog ; since, on a ge- 
nera! view, they appear to consist merely of 
head and tail. Their motions are extremely 
lively, and they are often seen in such vast 
numbers as to blacken the whole water with 
their legions. They live on the leaves of 
duckweed and other small water-plants, as 
well as on various kinds of animalcules, See. 
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 fur- 
nished with extremely minute teeth or den- 
ticulations. The. tadpole 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 sur- 
face of aquatic plants, &c. From this part 
it also occasionally hangs, when very young, 
by a thread of gluten, which it seems to ma- 
nage 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 re- 
spects ; the intestines in particular are always 
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 sometimes later, are succeeded 
by the fore legs, which are indeed formed 
beneath the skin much sooner, and are occa- 
sionally protruded and again retracted by the 
animal through a small foramen on each side 
of the breast, and are not completely stretch- 
ed forth till the time just mentioned. The 
animal now bears a kind of ambiguous ap- 
pearance, partaking of the form of a frog and 
a lizard. The tail at this period begins to 
decrease, at first very gradually, and at length 
so rapidly as to become quite obliterated in 
the space of a day or two afterwards. The 
animal now ventures upon land* and is seen 
wandering about the brinks of its parent wa- 
ters, and sometimes in such multitudes as to 
cover a space of many yards in extent. This 
is the phenomenon which has so frequently 
embarrassed the minds not only of the vul- 
gar, but even of some superior characters in . 
the philosophic world; who, unable to ac- 
count for the legions of these animals with 
which the ground is occasionally covered in 
certain spots, at the close of summer, have 
been led into the popular belief of their hav- 
ing descended from the clouds in showers. 
As soon as the frog has thus assumed its 
perfect form, it feeds no longer on vegetables 
but on animal food ; supporting itself on 
small snails, worms, &c. and insects. For 
the readier obtaining its prey, the structure 
of its tongue is extremely well calculated, 
being so situated that the root is attached to 
the fore rather than the hind part of the 
mouth; and when at rest, lies backwards, 
as if the animal was swallowing the tip. By 
this means the creature is enabled to throw it 
out to some distance from the mouth, which 
is done with great celerity, and the bifid and 
glutinous extremity secures 'the prey, which 
is swallowed with an instantaneous motion, 
so quick that the eye can scarcely follow it. 
The frog can hardly be said to arrive at its 
full size till the age of about five years, and 
is supposed to live at least twelve or fifteen 
years. 
The frog is extremely tenacious of life, 
and, like other amphibia, will survive for a 
considerable space the less of many of its or- 
gans. If confined entirely under water, it is 
still enabled to support its existence for seve- 
ral days, as appears by sir Thomas Brown's 
experiment, who kept a frog under water six 
days. On the contrary, it cannot so well 
dispense with the want of water, and is unable 
to survive too long an exposure to a dry air 
and a iiot sun. It is, therefore, particularly 
careful to secure a retreat where it may en- 
joy the benefit of shade and a sufficient sup- 
ply of moisture. It delights, however, to 
bask occasionally in a moderate sunshine, 
and is unable to support severe cold. 
2. Rana esculenta, green frog. This spe- 
cies is the largest of the European frogs, and 
is found plentifully in France, Italy, Ger- 
many, and many other parts of Europe, but 
is a rare animal in England. In its general 
appearance it extremely resembles the com- 
mon frog, but is of larger size, and of au olive- 
green colour, distinctly and strongly marked 
on the upper parts of the body with mode- 
rately large and somewhat rounded black 
spots or patches ; the limbs are elegantly 
marked or barred transversely with bauds of 
the same colour. The head is rather larger j 
and sharper in proportion than that of the j 
Common frog ; and the long deep-brown j 
patch under each eye, which forms so con- ; 
stant and conspicuous a character in that ani- | 
mal, is much less distinct, and sometimes 1 
even entirely wanting. The proportion of 
the limbs is nearly the same as in the com- 
mon frog, and the hind feet are very strongly 
pal mated. 
The green frog is a very voracious animal, 
and will occasionally seize on young birds of 
various kinds, mice, and even young duck- 
lings which happen to stray too far from their 
parents, swallowing them whole like the rest 
of its prey. It arrives at its full growth in 
about four years, begins to breed at the age 
of five years, and lives to about sixteen. 
3. Rana catesbeiana, bull-frog. This re- 
markable species is not uncommon in many 
parts of North America, where it is known 
by the name of the bull-frog, its voice resem- 
bling the distant lowing of that animal. It 
grows to a very large size, and is about 18 
inches from the nose to the end of the hind 
feet. Its colour, on the upper parts, is a 
dusky olive or brownish, somewhat irregu- 
larly marked with numerous deep-brown 
spots ; while the under parts are of a pale or 
whitish cast, with a tincture of yellowish 
green. 
m3 Z2 
, . 3 17 
j 4. Rana ignea, fire-frog, is a native tf Cef- 
, many, Italy, and many other parts vf £o- 
j rope, but Is nol found in England. Its colour 
| on the upper parts' is a dull olive-brown, the 
j skin being marked with large and small tu- 
i bercles ; round the edges of the mouti: is 
i placed a row of blackish streaks or peraerdi- 
j cnlar spots. The under parts both of die 
body and limbs are orange-coloured, spotted 
or variegated with irregular markings of dull 
blue. It is from the colour of the under sur- 
face that this species lias obtained its titles of 
bufo igneus, fire-frog, & c. 
This animal may be considered rather as 
an aquatic than terrestrial species, being 
rarely found on land, but chiefly inhabiting 
turbid stagnant waters, in which, in the 
month of June, it deposits its spawn, the ova 
being much larger in proportion than in liid^t 
others of the genus. The tadpoles are hatch- 
ed towards the end of June, and are of a pale 
yellowish-brown colour; and when young 
are often observed to hang from the surface 
of leaves, &c. by a glutinous thread proceed- 
ing from the small tube or sucker beneath the 
lower lip. 
The fire-frog is a lively, active animal; 
leaping and swimming with equal or even 
superior agility to the common frog. When 
surprised on land, or unable to escape, it squats 
close to the ground, at the same time turn- 
ing back its head and limbs in a singular man- 
ner ; and if farther teased or irritated, eva- 
cuates from the hinder part of the thighs a 
kind of saponaceous frothy fluid, of fio bad 
scent, but which in some circumstances has 
been found to excite a slight sensation of acri- 
mony in the eyes and nostrils. This species 
is observed to breed at the age of three 
years, and may be supposed to live about 
ten ; but this is not entirely ascertained. Its 
voice, according to Roesel, is sharper or 
lighter than in other frogs, less disagreeable, 
and in some degree resembling a kind of 
laugh; according to authors, however, it 
rather resembles the tone of a bell, or the 
note of a cuckoo ; for which reason the ani- 
mal has been called rana bombina. The 
male only is vocal. 
5. Rana piscis, larva, or tadpole. This ani- 
mal is a native of South America, and seems 
to be more particularly found in Surinam 
than in other parts. In its general form it 
very much resembles the rana temporaria, 
or common European frog ; and is, when liv- 
ing, of a yellowish olive-colour, spotted and 
variegated on the body and limbs with ru- 
fous or yellowish brown ; the principal mark 
of distinction from others of the genus being 
the somewhat oblique longitudinal stripes on 
the hind legs: the fore feet have only four 
toes, and are unwebbed ; but the hind feet 
have five, and are very deeply palmated to 
the very ends or tips of the toes ; and near 
the thumb or shortest toe is an oblong callus, 
resembling an additional or spurious toe. 
The tadpole of this frog, from its very large 
size, the strong and muscular appearance .of 
the tail, and the ambiguous aspect which it 
exhibits in the latter part of its progress to- 
ward its complete or ultimate form, lias long 
continued to constitute the paradox of Eu- 
ropean naturalists ; who, however strong and 
well-grounded their suspicions might be rela- 
tive to its real naturb, and the mistake of 
most describees, were yet obliged, in some 
