He then refers to successive irruptions and retreats of the sea, "the final result of which, however, has been a universal depression of the level of the sea." "These repeated irruptions and retreats of the sea have neither been slow nor gradual; most of the catastrophes which have occasioned them have been sudden." He then adds his proofs of the occurrence of revolutions before the existence of living beings. Like Lamarck, Cuvier was a Wernerian, and in speaking of the older or primitive crystalline rocks which contain no vestige of fossils, he accepted the view of the German theorist in geology, that granites forming the axis of mountain chains were formed in a fluid. We must give Cuvier the credit of fully appreciating the value of fossils as being what he calls "historical documents," also for appreciating the fact that there were a number of revolutions marking either the incoming or end of a geological period; but as he failed to perceive the unity of organization in organic beings, and their genetic relationship, as had been indicated by Lamarck and by Geoffroy St. Hilaire, so in geological history he did not grasp, as did Lamarck, the vast extent of geological time, and the general uninterrupted continuity of geological events. He was analytic, thoroughly believing in the importance of confining himself to the discovery of facts, and, considering the multitude of fantastic hypotheses and suggestions of previous writers of the eighteenth century, this was sound, sensible, and thoroughly scientific. But unfortunately he did not stop here. Master of facts concerning the fossil mammals of the Paris Basin, he also--usually cautious and always a shrewd man of the world--fell into the error of writing his "theory of the world," and of going to the extreme length of imagining universal catastrophes where there are but local ones, a universal Noachian deluge when there was none, and of assuming that there were at successive periods thoroughgoing total and sudden extinctions of life, and as sudden recreations. Cuvier was a natural leader of men, a ready debater, and a clear, forcible writer, a man of great executive force, but lacking in insight and imagination; he dominated scientific Paris and France, he was the law-giver and autocrat of the laboratories of Paris, and the views of quiet, thoughtful, profound scholars such as Lamarck and Geoffroy St. Hilaire were disdainfully pushed aside, overborne, and the progress of geological thought was arrested, while, owing to his great prestige, the rising views of the Lamarckian school were nipped in the bud. Every one, after the appearance of Cuvier's great work on fossil mammals and of his _Règne Animal_, was a Cuvierian, and down to the time of Lyell and of Charles Darwin all naturalists, with only here and there an exception, were pronounced Cuvierians in biology and geology--catastrophists rather than uniformitarians. We now, with the increase of knowledge of physical