88 Bateachiaus REPTILES. Bateachians. 
this prey they watch with great patience till it comes 
within their reach. They then dart upon it with great 
velocity, shooting out the tongue in order to catch it 
by means of the viscid secretion by which it is covered. 
This fluid appears to retain the object seized, while the 
two points of the bifurcation seem to twist round it. 
The prey once seized, it is speedily swallowed, the 
animals pushing it into the oesophagus with the thumbs 
of their fore feet. In consequence of their feeding on 
worms and mollusca, frogs are useful animals in gar- 
dens, as they destroy great numbers of slugs and 
worms, which are so hurtful in these places. Frogs, 
having the toes of the hinder feet webbed, swim remarlo- 
ably well in the water ; and on land their mode of 
progression is by a series of successive short leaps — 
fig. 24. These animals are generally found in moist 
Fig. 24. 
Mouth and fore and hind feet of Kana Occipitalis-rto show structure of toes and tongue of the group Kanina, or Frogs* 
places, in the grass of meadows, and on the banks of 
streamlets, into which they continually leap and dive. 
In summer, during or after w'arm rain, they make their 
appearance in our meadows in such vast quantities, that 
many people have imagined that it had rained frogs. 
This is an ancient belief, and is still in full credit in 
the provincial pai'ts of many countries of Europe. 
Several of the old authors have mentioned this sudden 
appearance of these creatures ; and Aristotle, in noticing 
the phenomenon, calls the frogs so suddenly called as 
it were into existence, diopetes {hlu’Zirrig), or “ sent 
from Jove.” The males of some species, especially 
the Edible or Green frog, have two sacs called vocal 
pouches, on each side of the throat, which in general 
are only manifested externally by the swelling which 
is produced in them when filled with air. These ani- 
mals have a peculiar and sonorous cry, louder and 
stronger in the species with the vocal sacs, which is 
known in this country b}^ the name of croaking. It is 
chiefly during rain in warm weather, and in the morn- 
ing and evening, that we hear this noise, which must 
be familiar to every one. In autumn, when the sum- 
mer heats are over, these animals appear to lose their 
voracity, and cease to take food ; and when the cold 
becomes more considerable, they protect themselves 
from its rigour by sinking into the mud of deep waters, 
or by taking up their abode in holes on the banks of 
streams and ditches. They sometimes assemble in one 
place in such quantities as to cover the soil to the 
depth of a foot, and thousands may thus be taken in a 
few minutes. In this country they revive upon the 
return of spring, and emerge from their winter retreats 
to recommence a life of activity and obey the grand 
law of nature — the reproduction of their species. The 
arrival of the season for this important function is 
shown in the male bj^ the appearance of a black wart 
on the fore feet, and the belly swelling. The male 
frog leaps on the back of the female, to whom he clings 
by the aid of these warts on his fore feet. During the 
cohesion of the two sexes, which lasts for a consider- 
able period, sometimes for fifteen or even twenty days, 
the female commences depositing her eggs, which are 
fecundated during their passage by the seminal fluid of 
the male. When first expelled these eggs are globular, 
black on one side, and whitish on the other. They 
are enveloped in a glairy or glutinous transparent 
mass, which serves for the nutriment of the embryo, 
and swell greatly in the water after they are laid. 
They are, in the case of the common frog of this 
country, deposited at the bottom of the water, and 
then float on to the surface, and are left there to hatch 
by the ordinary temperature of the atmosphere. The 
number deposited at each laying is very great, as many 
it is said as from six hundred to twelve hundred 
annually. Swammerdam once counted eleven hundred, 
and Montbeillard thirteen hundred, from one female. 
The development of the young is more or less rapid 
according to the temperature of the atmosphere. In 
a few hours after its expulsion the egg begins to show 
a slight change. At the end of about fifty hours, when 
the temperature is high, the embryo may be seen 
within the egg, with the head well marked, the tail 
somewhat elongated, and even the rudiment of the 
membrane or web which is destined to form its fin is 
visible. The development then goes on gradually, till, 
according to Professor Bell, in the ordinary temperature 
of this country, at the end of a month the young crea- 
ture bursts its shell and comes forth in the well-known 
state of a tadpole. At this stage of its existence it is 
blind and destitute of feet. It has a large liead, a 
globular belly, a long tail, and external gills by which 
it respires. It feeds solely on vegetable substances, 
