the Artiodactyl and Perissodactyl Ungulata is representative of the best morphological work; and Owen rendered the greatest service to morphology in 1843 by his clear definition of analogy and homology—the former being illustrated by "a part or organ in one animal which has the same function as another part or organ in a different animal"; the latter being illustrated by "the same organ in different animals under every variety of form and function," i.e. organs of similar development and structure are homologous; organs of similar function are analogous. The further elaborations of homology, due to the doctrine of evolution, etc., have been worked out by Agassiz, Bronn, Haeckel, Mivart, Lankester, and others. Owen is the connecting-link between Cuvier and the present school of biologists. On the one hand, he was unappreciative of Darwinism, and on the other, "really believed in the derivation of species from one another." He will always be remembered, as long as natural history exists, for his practical work in comparative anatomy and palæontology; but many of his philosophical ideas have been superseded by the work of modern biologists. It was unfortunate that Owen did not appreciate the work of Darwin and others. He was unable to accept the theory of the origin of species by natural selection, but his investigations did much to prepare the way for the general and rapid acceptance of Darwin's theory, since it was felt that there must be some strictly scientific explanation of the affinities by which
