188 DIVISION I. VERTEBRAL ANIMALS.—CLASS III. REPTILIA. 
consequently the best known, group of the Batrachian family. They are 
distributed through all regions, and, we believe, there is no land where their 
singularly-varied voice is not heard, either as a harbinger of the opening 
spring, or a sure prophecy of approaching rain. They have a somewhat 
slender body, and four legs, the hinder ones very Jong, and the feet pal- 
mated. “Their head is flat, the muzzle rounded, the mouth deeply cleft, 
and the greater number have a soft tongue attached only to the lower part 
of the gullet, but which extends forward to the jaw, and is doubled back 
above. Their fore feet have only four toes, but the hinder sometimes show 
the rudiment of a sixth. The males have, on each side, under the ear, a 
delicate membrane, which is inflated with air when they croak. 
“Their skeleton is entirely deprived of ribs. A cartilaginous plate, even 
with the head, takes the place of tympanum, and renders the ear visible 
externally. The eye has two fleshy lids, and a third, which is horizontal 
and transparent, concealed by the lower one. 
“The inspiration of air is produced simply by the movements of the mus- 
cles of the throat, which, by dilating, draw in the air through the nostrils, 
and, by contracting, whilst the orifices of the nostrils are closed by means 
of the tongue, force the air into the lungs. Ixpiration, on the contrary, is 
eflected by the contraction of the muscles of the lower belly. 
“The eges are fecundated at the moment they are laid, and the young is 
termed a Tudpole. It is at first provided with a long, fleshy tail, and a 
small, horny beak, but with no other apparent members besides certain little 
fringes at the sides of the neck. These disappear after some days, but 
Swammerdam assures us that they still exist as gills underneath the skin. 
The latter are minute crests, which are very numerous, attached to the four 
cartilaginous arches, placed on each side of the neck, adhering to the hyoid 
bone, and enveloped by a membranous tunic, which is covered by the gen- 
eral skin. The water, entering by the mouth, to bathe the intervals of 
these cartilaginous arches, passes out either by two orifices or by a single 
one, according to the species, pierced through the external skin, either on 
the middle or on the left side of the animal. The hind feet are gradually 
developed to view, by little and little, while the anterior likewise appear 
beneath the skin, but do not burst it for some time later. The tail is 
absorbed by degrees. The beak falls, and occasions the genuine mandibles 
to appear, which had previously been soft, and were concealed underneath 
the skin. The gills shrink, and are obliterated, leaving the lungs to perform 
their functions unassisted by them. The eye, which in the Tadpole was 
only visible through a thinner space in the skin, becomes apparent with its 
three lids. The intestines, previously very long, slender, and spirally contort- 
ed, shorten, and acquire the enlargement of stomach and colon. The Tadpole 
