The Natter-jack. REPTILES. Tree-frogs. 93 
tlie fore ones, and finally the whole is detached, 
pushed by the two hands into the mouth in a little 
ball, and then swallowed at a single gulp ! 
THE NATTER-JACK {Bu.fo calamita) is another 
European species, and is found, equally with the com- 
mon toad, in various parts of Great Britain. It is, 
however, much more local than the other, and appears 
confined to certain districts. It is said to be truly 
indigenous to Ireland, the only instance of an indi- 
genous native reptile in that country. It is not quite 
so large as the common toad, the body being only 
about two and three quarter inches in length. It is of 
a light yellowish-brown colour, clouded with dull olive, 
a bright yellow line running along the middle of the 
back. The Natter-jack is not so “ heavy-gaited” as 
the common toad, for when it is excited it runs toler- 
ably quick, its body being raised considerably above 
the ground during its progress. It is far more capable 
of sustaining drought than the other species, and is 
often observed to climb on walls and trees, and con- 
ceal itself in holes. Professor Bell says that this 
animal is very common in his garden at Selborne, 
and that he has often found several of them lying 
under the shallow layer of turf covering the top of a 
wall of a ha-ha there, exposed to the powerful rays of 
the summer’s sun, in the hottest and dryest situation 
in the garden. It is common in France, and in Saxony 
it is frequently found in the houses. It never goes to 
the water but for the purpose of reproduction ; the 
union of the two sexes taking place in spring, in the 
water, and the metamorphosis of the young undergoing 
the same stages as the common toad. The skin of 
the Natter-jack is said to exhale a strong odour of gun- 
powder. 
America produces a number of toads, and of various 
sizes, but we hasten on to the curious “ Tree-frogs.” 
TBEE-FEOGS {Hylina). 
The second series of Batrachians with the tongue 
adherent in front {Opisthoglossa), is composed of 
species which have the fingers and toes dilated into 
discs at the extremities — fig. 26. These form the 
Fig. 26. 
Ilyla— fore feet and dilated toes of two species. 
Broad-tced Opisthoglossa {Opisthoglossa platydactyla), 
and are synonymous with what are well known as Tree- 
frogs. The species are numerous, and by far the greater 
number belong to the section Hylina, which is charac- 
terized by the animals belonging to it having maxillary 
teeth and a well and perfectly developed ear. Tree- 
frogs form a very natural group of Batrachians, and 
the distinguishing character of the fingers and toes being 
dilated into discs covered with a viscous secretion, is 
most important, and influences their whole mode of 
existence. By means of this organization these crea- 
tures can adhere to smooth surfaces, as glass, leaves of 
plants, &c. ; and they are thus enabled to climb trees, 
to leap from branch to branch, and to traverse with 
facility the moving leaves of plants, shrubs, and trees 
agitated by the wind. Their actions are more like 
those of a bird than a reptile, and their great agility 
and extraordinary suppleness render them able to 
make their way with great dexterity on the most 
flexible branches. The mode, however, in which 
these animals are qualified for their arboreal habits 
yet remains to be explained. “ The monkey,” as Mr. 
Martin remarks, “ grasps with his paws the perch on 
which he rests ; the bird with its claws ; the snake 
entwines itself around the branch ; the iguana uses 
its long toes and hooked nails ; the chameleon holds 
the bough tight between its vice-like toes ; but the 
foot of the Tree-frog acts differently from the foot of 
these animals. It is not a grasping organ, nor is it 
furnished with claws for clinging ; but it is provided 
with suckers, analogous to those we have noticed in 
the foot of the gecko. On the under surface of each 
finger (both of the fore and hind paws) at the tip, 
which is enlarged and rounded, is placed a sucker, 
consisting of a little cushion, moist with a thick glutinous 
fluid, and applying itself so closely to the surface it 
touches as to support the creature’s weight. This 
mechanism is, however, under the animal’s control, 
as it can disengage or fix its fingers at will.” The 
Tree-frogs feed upon all kinds of insects, small worms, 
&c., and during the fine weather of summer they pur- 
sue their prey amongst the leaves of the trees, on which 
they then reside, with astonishing agility. Later in the 
season, however, they retire to the bottom of ponds, 
and, like frogs, pass the winter there in a state of tor- 
pidity. The union of the sexes takes place also in the 
water, the spawn is deposited there, and the develop- 
ment of the eggs and young take place in the same 
manner as in the frogs and toads. They are noc- 
turnal in their habits. In the day-time, and particu- 
larly when the heat of the sun is greatest, they shelter 
themselves in shady places, where the trees afford a 
thick foliage ; but when twilight begins they put them- 
selves in motion, and enjoy their sports and gambols 
in security. The males are provided with large vocal 
sacs, and the croaking noise which they produce is 
stronger even than in the Edible frog itself. During 
or previous to rain, and in the middle of the fine nights 
in summer, the Tree-frogs may often be seen assem- 
bled in numbers on the tops of trees, sending forth in 
chorus their hoarse and discordant music. Besides 
the dilated tips of the fingers and toes possessed by 
these animals, they have another character which dis- 
tinguishes them from the tribes already noticed. This 
is the existence of numerous small granulations with 
glandular openings on the inferior surface of their 
belly. Their hind legs also are very long. 
