2636 FROGS AND TOADS 



they are further mostly characterized by the webbing of the toes of the fore- 

 feet, although the degree to which this is carried is variable. The tips of the 

 toes are always expanded into round discs, and very generally their terminal joints 

 are forked. The males are provided with one or two internal vocal sacs. In habits 

 these frogs are strictly arboreal; their bright green coloration harmonizing with 

 the leaves among which they dwell. The larvae are remarkable for the pos- 

 session of an adhesive disc behind the mouth on the tinder surface; while the 

 muzzle is prolonged into a proboscis, and the single breathing pore is situated on 

 the right side of the body, nearer to the tail than to the muzzle. Writing of the 

 habits of one of the Cingalese members of the genus ( formerly separated as Polype- 

 dates] , in which the front toes are only half webbed, Emerson Tennent observes 

 that it "possesses in a high degree, the faculty of changing its hues; one as green as 

 a leaf to-day will be found gray and spotted like the back to-morrow. One of these 

 beautiful little creatures, which had seated itself on the gilt pillar of a lamp on my 

 dinner table, became in a few minutes scarcely distinguishable in color from the 

 ormolu ornament to which it clung. ' ' 



THE SOLID-CHESTED TREE FROGS 

 Family DENDROBA TIDsE 



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 proc- 

 esses 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 repre- 

 sented 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 one-half in length, is widely distributed in tropical America, and is remarkable 

 for its variability in color, some examples being uniformly" black, others gray above 

 and black on the sides and beneath , and others gray 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 

 gray with black spots; while in other cases, the ground color 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 



