Before leaving the subject of Huxley's contributions to vertebrate anatomy, the actual details of which would occupy far too much space, it is necessary to mention the great importance to zoölogy of the new terms and new ideas he introduced into classification. His mind was, above all things, orderly and comprehensive, and while, in innumerable minute points, from the structure of the palate of birds to the structure of the roots of human hair (actually the subject of Huxley's first published contribution to scientific knowledge), he added to the number of known facts, he did even more important work in co-ordinating and grouping together the known body of facts. To him are due not only the names, but the idea, that the mammalian animals fall into three grades of ascending complexity of organisation: the reptile-like Prototheria, which lay large eggs, and which have many other reptilian characters; the Metatheria, or marsupial animals; the Eutheria, or higher animals, which include all the common animals from the mole or rabbit up to man. In a similar fashion, he grouped the vertebrates into three divisions, and named them: Ichthyopsida, which include the fish and Amphibia, creatures in which the aquatic habit dominates the life history and the anatomical structure; Sauropsida, including birds and reptiles, on the close connection between which he threw so much light; Mammalia. CHAPTER IX MAN AND THE APES Objections to Zoölogical Discussion of Man's Place--Owen's Prudence--Huxley's Determination to Speak out--Account of his Treatment of _Man's Place in Nature_--Additions Made by More Recent Work.