He rejected the view, held by Lamarck. that a linear classification of the animal kingdom is possible, and in his great work, 'Le Rims Animal' (1817). he grouped his classes in four embranchements, representing four flunks mentally distinct types of structure. These branches, with their contained classes, are as follows: Vertebrate, including Mamma/ix Birds, Reptiles, Fishes; Molluscs, including Cephalopoda. Pteropoda, Gasteropoda, Acephala, Brachiopoda, Cirrhopoda; Arsicalata, including Annelides, Crustacea, Arachnicks, Insects; and Radials, including Echinoderms, Intestasal Worms, Acalephn, Polypi, Infusoria. He raised comparative anatomy to the dignity of a trot science, and he carried out researches of the utmost value in palaeontology. In the restora tion of extinct animals from remains of parts he used his law of the correlation of parts ac cording to which animals are so constituted that single organs or parts can serve as an index to all other parts and to the general strut e. The system of Coyler has been exteasively modified by many subsequent anatomists; nom 14y Lamarck. De Blainville, Ehrenberg. Owen, Wihte-Edwards, Von Siebold. Stannins. Leach art, Agassiz, Huxley, Haeckel and others. The present state of classification must not be re garded as authoritative or final, since the rapid progress of knowledge is introducing incessant change in our conceptions of the relations of the greater groups. The reverse error must however. be guarded against — that of suppos ing one classification as good as another, for each really marks a stage of progress.
Darwin and The theory of the fixity of species was challenged at various tunes by different zoologists, notably by Lamarck. but it was not till the publication of 'The Origin of Species' (1859) by Charles Robert Darn!.
(1809-82) that the old view became gencralb abandoned and the evolution or devekipsnort theory took its place. This has oompleteb transformed the whole outlook of the soolonst and has brought new branches of the science into being, notably thremnuitology. It makes the tree-like classification to which systematists have steadily advanced a truly genealogical tree.
and it has contributed enormously to the rem of what may be called philosophical ogy. The natural-selection principle was inde pendently discovered at practically the same time by Alfred R. Wallace (182.3-1913), the eminent naturalist-traveler. Herbert Spencer had also formulated an evolution theory, ex tending to the whole of nature and life. Thomas Henry Huxley (1825-95), master of an ad mirably lucid and attractive method of exposi tion, and Ernst Hieckel (1834-), have done admirable work in embryology and other branches of zoology, and have contributed much to developing and popularizing the Darwinian views. August Weismann (1834-1914) is best known by his valuable contributions to the doc trine of heredity. The number of other zool ogists who have done good work during the Darwinian period and under the influence of the Darwinian conceptions is so great that no att t will be made to enumerate them.
Bi ' aho hy.—Lamarck, 'Philosophic Zoo kirthue' Paris 1809),• Carus, der Zoologie' (Leipzig 1812); Spencer, 'Principles of Biology) (London and New York 1898); Osborn, 'From the Greeks to Darwin' (New York 1894); /dial!, 'Early Naturalists' (Lon don 1912) ; 'Cambridge Natural History' (10 vols., New York 1895-1909) - Lankester, E. R., 'Zoology' (ib. 1906); Parker and Haswell. 'Zoology) (2 vols., ib. 1910); Zoological Rec ord (London, annually).