Another curious Rana is the Tree-frog. He is smaller than any of his cousins, and may be known by his bright green dress, which is spotted with black, and by a membrane stretched between his toes, which gives him a broad, flat surface, while it helps to sustain him as he leaps, somewhat after the fashion of a flying squirrel, from branch to branch. In tropical regions, where many of the trees are bedecked with gorgeous blossoms, Tree-frogs appear in the gayest of colors, the splendor of their garb being protective in such surroundings.
Dressed in black and light brown, and living in marshes in the Eastern United States, is another species--the Swamp-frog. His voice is a prolonged croak, which, to the practised ear, can be readily distinguished from the bawl of Clamata, or the roar of the Bull-frog.
Cats, geese, hawks, vultures, owls and other animals eat frogs, and the luckless creatures can scarcely appear without finding an enemy. But nature, who is a very wise and considerate mother, provides a means for balancing this great destruction of their forces in endowing them with wonderful reproductive organs. So prolific are frogs, that when the little black tadpoles appear, so thickly are they huddled together that the pond seems literally alive with their swimming forms.
In the same class of animals to which the frogs belong, as well as to the same order, but to a different sub-order, are placed the toads, somewhat remote cousins of the frogs. As the frog is well-known about our ponds, so the toad is a constant denizen of our groves and gardens. The frog, you have been told, is a species of Rana, and now I shall introduce to you the toad as a species of Bufo. In general anatomy they are alike. Their eggs and young are closely similar, and the stages of growth from egg to adult form are nearly identical. When the adult stage is attained the frogs and toads are very tiny creatures, but, small as they are, they are readily distinguishable from each other by the conformation of the snout, and by the larger development of the hind-legs of the frog. Their chief differences will now be enumerated. The toad has no teeth, but the frog, as has been stated before, has teeth in both the upper jaw and the palate. Similarly attached is the tongue, but the free end of the frog’s tongue is forked, and the toad’s entire. The skin of the toad is usually warty, while the frog’s is smooth. A rounder body, shorter hind-legs, less fully webbed feet and more rounded snout still further distinguish the toad from the frog. Their soft moist skin shows them to be Amphibians. The absence of tails places them among the Anuran, or Tailless Amphibians. Thus far they agree well together, but differences loom up upon careful examination, and we are compelled to say of the frog that he belongs to the Ranidæ, and of the toad that he belongs to the Bufonidæ. Of the two animals, the toad is by far the more interesting and useful.