called the “flying frog” and the “tree frog.” The webbed feet are large, and when spread out serve to bear up the body, as would paper kites of the same size. But the animal does not fly. It is active, and leaps from branch to branch expertly, and, when it wants to descend, by spreading those fan-like feet, it comes down with less violence. Tree toads are noisy little creatures, and seem to be ventriloquists, as their voices do not indicate their true position. This deception, and their color, make their capture more difficult. CLASS II.—REPTILIA. ORDER I.—_Ophidia_,[2] or serpents, are oviparous, air-breathing vertebrates, having round, tapering bodies. They crawl or glide on their ventral surface. The serpent’s body is very flexible. Its numerous vertebræ, concave in front, and hemispherically convex behind, are so jointed as to allow a free horizontal motion. Its progress is usually by lateral undulations, made practicable by the great number of the vertebræ, attached flexible ribs, and muscles along the sides, specially arranged for prompt action on the spinal column. The bones of the head are loosely jointed, and movable, making the mouth very dilatable. The sharp teeth are hooked backward, so that whatever is seized is likely to go down the capacious throat. The entire skeleton and skin are so elastic that objects much larger than the serpent, in its normal condition, can be swallowed whole. Though without limbs, they perform with dexterity a great variety of movements; creep, climb, swim, raise the body almost erect, and spring from the ground. There are two classes, the poisonous and the harmless. Of the former the Cobra, Copperhead, Viper, and Rattlesnake are representatives. They have extensile fangs, and, along the side of the upper jaw, a large gland, which secrets a poisonous liquid that is injected through the hollow or grooved fangs into the wounds they inflict. Harmless snakes have much the same structure, but nothing of this special arrangement. ORDER II.—_Lacertilia_[3] or lizards, are snakes with short legs, and usually much quicker in their movements than most other reptiles. Most species are harmless, though a few are said to be venomous, and, because of them, all are dreaded. They differ much in appearance, some being really beautiful, and others about as hideous as reptiles can be. There are an immense number and variety of lizards, having some distinctive characteristics. Several extinct species, as the Iguanadon,[4] Megalosaurus,[5] Plesiosaurus,[6] and Ichthyosaurus,[7] are known only by their gigantic fossils, casts of which may be seen in many of our college museums.