CLASSIFICATION OF VERTEBRATES. Fishes.— Ichthyology began as a science with Artedi tq.v.), wit made a division into live classes, in a useful but very artificial manner. This con tinued substantially unchanged until the gigan tic labors of envier resulted in a revised classi fication, much nearer nature, recognizing clearly the distinction between the fishes with bony skeletons and those with cartilaginous skeletons. Agassiz followed with a classification based upon the forms of the scales, the most important fea ture of which was the recognition of the group Gammidei. The next great generalization in this direction of systematic arrangement was that of J. who developed the distinctness of Amphioxias and the lampreys from other car tilaginous fishes, and so established the new' groups Cyelostomi and Leptoeardii; lie also pro posed the group Dipnoi for Lepidosiren. Hux ley's studies and new material threw new light upon the subject, and aided Gunther to form a classification of fishes which. with one im portant exception, is still held by ichthyologists. For details, see Fist!.
.:I mph ibia,The Amphibia were for a long time confused with the Reptilia. Thus 1767. who first used the term Amphibia as a group-name. included under it: (I) Reptiles pcdati, including turtles ( Test udn ) Dra co Lacerta ( including crocodiles, lizards, and newts) ; and Rana. (2) ticrpentes apodi. (3) Nantes pin na li, including certain fishes. gniart. 1800. classifies reptiles as: Chelonia, Ophiiiii, and Batraehii (the last includ ing frogs, toads, and newts). Latreille. 1804: Dummsril, 1806: and Oppel. ISM while more sharply discerning the true subdivisions of am phibians, still retain them under the head of reptiles. First, De Blainville, writing in 1816, makes Reptilia and Amphibia coardinate, but subdivisions of the `Amphibians:' so likewise :ztannins, as late as 1856. Latreille, 1S21, how
ever. proposes a classification which is essen tially the same as that we now accept.
Reptiles.—Reptiles were put by Linn:ens under the class Amphibia, and it was not until Broil gniart separated them that herpetology began upon a philosophic basis. It was further ad vanced by Dum(mril (1807) and Oppel (1811). who placed Cawilia with time amphibians. Cuvier and other writers did little to establish a ra tional system within this group; and even Du Inc.ril and Ribron, in their great ErpOologie re'te'rale (1834-54), cling to the idea that the batrachiuns are only separable as an order from reptiles. Although De Blainville, Leuckart, and others had advocated a min•h deeper separation, it was not until Huxley's investigations dem onstrated the necessity of regarding the Am phibia and Reptilia as distinct classes that they were so set apart. See REPTILE.
Huxley, in his .Inatomy of Vertebrate(' A ni snalv 11871 ). divided the Vertehrata into lehthsopsida ( fishes. leptoeardians, ma rsipo branths, and Amphibia), Sauropsida (birds and reptiles), and Alanottalia.
Itani»nits and Birds.—Birds were too easily distinguished and too compact a Blass to have been much confounded with anything else, though medieval writers often put bats, bees, etc.. under the name. The history of their elassi ficati , therefore, falls within lines agreed upon from the first, and belongs to the article Bum. The same may be said of the class Manunalia, where the only r011f u,:i(m arose from the foolish ness of a few mediaeval authors. who classed bats among birds. and whales with aisle.; the history of its classification will be found under MA31 :%1 ALIA.