SOLID-CHESTED TREE-FROGS, 
271 
The Solid-Chested Tree-Frogs. 
Family Dendbobatidje 
As we have already seen to be the case with the snakes, two totally distinct 
families of frogs have taken to an arboreal life, and have thus become so like one 
another that we have to depend on anatomical differences for their distinction. 
In the present family, while the structure of the bones of the chest is of the same 
solid structure as obtains in the typical frogs, and the extremities of the transverse 
processes of the sacral vertebra are not expanded, an important difference presents 
itself in the absence of teeth in the upper jaw and on the palate. The toes of both 
feet are quite free from webs, and have their tips expanded into rounded discs. 
These frogs are represented by two genera, one of which ( Mantella ) is confined to 
Madagascar, and is distinguished by the tip of the tongue being notched; while in 
Dendrobates of Tropical America the tongue is entire. The American genus is 
represented by seven species, among which the variable tree-frog {Dendrobates 
tinctorius) is selected for illustration. This pretty little frog, which measures 
barely an inch and a half in length, is widely distributed in Tropical America, and 
is remarkable for its variability in colour; some examples being uniformly black, 
others grey above and black on the sides and beneath, and others grey with large 
black blotches. This, however, is by no means the limit of variation, since some 
examples are black above, with two or three longitudinal white or pink stripes, the 
under-parts being grey with black spots ; while in other cases, the ground-colour is 
black, with white spots and streaks above, and spots or marblings of the same 
beneath. From the small size of the discs on its feet, which do not admit of its 
clinging to upright stems, this frog seems to be less arboreal than some of its 
allies; and it is generally found among fallen leaves on the ground in forests. 
Like its kindred, it displays remarkable care and attention to its young. The 
secretion from its skin is employed by the Indians as an arrow-poison. 
The Narrow-Mouthed Frogs. 
Family ENGYSTOMA TlDJE. 
An important family of the suborder is that of the narrow-mouthed frogs, 
represented by more than a score of genera, distributed over Africa, Madagascar, 
India and the adjacent countries, Southern China, Papua, and America. While 
agreeing with the members of the preceding family in the absence of teeth in the 
upper jaw, these frogs are distinguished by the broad expansion of the extremities 
of the transverse processes of the sacral vertebra. The vertebrae are similar in 
conformation to those of the typical frogs, and there is the same absence of ribs. 
There is, however, considerable variation in regard to the bones of the chest, 
several of the genera lacking the transverse bars commonly known as precoracoids; 
and the terminal joints of the toes may be either simple or T-shaped. Although 
there are no arboreal forms, the family comprises terrestrial, aquatic, and burrowing 
representatives; the last having either the front or hind-limbs specially strength- 
