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Page:Popular Science Monthly Volume 49.djvu/198

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POPULAR SCIENCE MONTHLY.

the same time being the species that furnishes the legs so much enjoyed by many epicures. When Huxley gave his biological chapter on these animals, he used the Anglo-continental types, R. temporaria and R. esculenta, the latter form being the one used for the table in Europe. One of the most interesting species that have been described is the one discovered by Mr. Wallace in Borneo a number of years ago. It has been popularly called the "flying frog," from the fact that it has toes of great length, and these are fully webbed to the tips. If the animal wishes to descend from the top of a high tree it has only to make the leap, and by spreading out its toes it converts its feet into four veritable parachutes, and thus this little aërial batrachian reaches terra firma in safety. Among the most curious types are the tree frogs; and Gibson says these "are readily distinguished from all others by having the ends of their toes dilated into knobs or disks, generally provided with a sticky secretion, by means of which they can cling to the leaves and branches of trees. They are small, elegant, and exceedingly active creatures, the males possessing loud voices, of which they make copious use during the breeding season and on the approach of rain." Frogs have from remote times been regarded as weather prophets, and at the present day, in some parts of Germany, the European tree frog (Hyla arborea) is used as a barometer. A few of them are placed in a tall bottle provided with miniature ladders, the steps of which they ascend during fine weather, seeking the bottom again on the approach of rain.

Anatomical structures of a variety of kinds are characteristic of different species of frogs, having to do with the voice organs. So it is that many croak, some chirp, and some almost bellow. Many emit noises most disagreeable to all ears, while others give vent to sounds that under some circumstances are quite enjoyable. Darwin says, "Near Rio de Janeiro I used often to sit in the evening to listen to a number of little Hylæ [tree frogs], which, perched on blades of grass close to the water, sent forth sweet, chirping notes in harmony." This, however, is not the case with another species that occurs in Surinam, also a tree frog, endowed with an extremely disagreeable voice, and, what is worse, they congregate together in great numbers, and then, when they unite in their piping, they have been known to drown the orchestra of the Paramaribo theater.

Frogs live principally upon insects, and these they capture with their peculiarly formed tongue. This organ is soft and extensible, being at the same time covered with a viscid secretion. Anteriorly it is closely attached to the floor of the mouth, while behind it is to a large degree free. The free part is thrust forward when the frog desires to capture an insect, and the latter