Flying Animals, in the strict sense, include most insects, birds, and bats, and these only. In past times there were 'flying reptiles' (Pterodactylus, Rhamphorhynchus), in which the outer finger was enormously elongated, and supported a wing-like expansion of the skin. In several ways these extinct forms were prophetic of birds, and certainly must be said to have had wings; but to what degree they were able to progress like birds in the air we do not know. For the true fliers, and for their interesting contrasts—e.g. between the wing of an insect and that of higher forms, or between the 'arms' of bat and bird—the relevant articles must be consulted; the present is devoted to a quite different set of animals, which are popularly called 'flying animals,' though they do not beat the air with wings.
(1) Among fishes, two very distinct genera (Exocetus and Dactylopterus) have the power of skimming for considerable distances above the surface of the water, their expanded pectoral fins forming a parachute (see FLYING-FISH). (2) Some species of lizards in the genus Draco—e.g. D. volans—take short swoops through the air, the skin being stretched on several much elongated ribs, so as to form a sort of half kite on either side (see DRAGON). In some Geckos (q.v.)—e.g. the Californian Phyllodactylus tuberculatus—there is not a little membranous fringing of body, tail, and limbs. The flying powers of Wallace's 'flying frog' (Rhacophorus) have not been certainly established. (3) It is, however, among mammals that attempts at parachute flight are most frequent, and that not in one order but in three: Marsupials (Petaurus), Rodents (Pteromys and Sciuropterus), and Insectivores (Galeopithecus).