40 ADAMITES AND PREADAMITES.
reported to be found under a sheet of Tertiary lava, are not sufficiently authenticated to form a subject of profitable discussion. And this is all. These are the only evidences on which the claims of pre-glacial man in Europe have rested. But if he was post-glacial, what measure of years may express his antiquity? This is equivalent to asking the remoteness of the decline of the glacial epoch, which the Stone Folk certainly witnessed. The following are the grounds of the opinion, current to some extent, that fifty or a hundred thousand years separate us from the men who saw the decline of the continental glaciers.
I. The astronomical hypothesis of glacial periods. Recent astronomers have suggested that the glacial period was only the last of a succession, and that changes in astronomical conditions must produce such periods with calculable regularity. M. Adhemar has argued that the northern temperate zone must be glaciated once in 21,000 years by the influence of the precession of the equinoxes: Thus, the secular winter might be supposed to have passed' about 10,500 years ago. But Mr. Croll, discrediting Adhemar, appeals to variations in eccentricity of the earth's orbit, and puts down 8o,000 years as the time elapsed since maximum eccentricity led to continental glaciations. Accordingly, we might put the decline of the glaciers at 50,000 years ago, and this would indicate the antiquity of the Stone Folk. But I hold that archaeology vetoes such a conclusion.
II. Contemporaneousness of man with animals now extinct. Geology once taught that all extinctions are remote in time; and hence, when man was found a contemporary with the mammoth and the cave bear, he was held to possess a high antiquity. But geology was mistaken. Extinctions have been recent. Extinctions are in progress. Continued extinctions are the order of nature. The Maories of New Zealand still retain traditions of the extinct gigantic birds of their islands. In Madagascar, the Dodo has lived within 250 years ; but it is now extinct, like the solitaire and the AEpyornis. The huge Rhytina gig-as has become extinct; as also the whale of the Bay of Biscay, which was once the basis of a flourishing industry. Other species are plainly approaching extinction. The Great Auk of Newfoundland has been seen but once in fifty years; and the Labrador Duck, ten