From these discoveries it is abundantly evident that man existed on the earth contemporaneously with the mastodon and other extinct mammals belonging to the Pleiocene and early Pleistocene eras. There are, however, people who stoutly deny that this can be so—at any rate, as regards Northern and Central Europe—and who rank the discoveries at Moulin Quignon, Engis, Kent’s Cavern, etc., with late Pleistocene remains. They maintain that the beds in which these relics were found could not have been of Pleiocene or early Pleistocene formation, inasmuch as they lie _above_ the till and boulder-clay which form the glacial deposits of the time when Europe was an Arctic region—that is to say, of late Pleistocene times. Therefore, they say, man’s earliest existence in Europe was post-glacial or late Pleistocene. But while the fact of the human remains having been discovered above the boulder-clay appears to point to a post-glacial date, still there is confronting us the perplexing anomaly of the contemporary existence of extinct mammals belonging to a tropical fauna, which, if we accept this theory, involves the necessity of admitting that a tropical climate followed the last glacial epoch—a condition of things that we know never existed at all. The fact is there have been more periods of glaciation than one, each being followed by the deposition of boulder-clays; and between the periods of intense Arctic cold there were intervals of tropical or sub-tropical heat, when mammals belonging to and requiring a tropical climate ventured as far north as the north of England, to become extinct when the period of glaciation supervened. The last glacial period, we know, extended its area of influence as far as the high peaks of Switzerland and Northern Italy, completely overwhelming the whole of Northern Europe as far south as the latitude of 45º, and the whole of North America as far south as the latitude of 40º; since when there has been a gradual diminution of cold until the present temperate climate supervened. Now, if it can be positively ascertained that all the boulder-clays found in England and Northern Europe were deposited during and immediately after this last glacial period, the date of man’s first appearance in those districts, as far as we have as yet any evidence, must be post-glacial; but in such a case it would have been impossible that a tropical fauna and flora could have existed in the same localities, whereas their remains have been abundantly found lying side by side with the remains of Palæolithic man. The conclusion we must draw is that the boulder-clays found below the remains of Palæolithic man could not have been deposited after the last period of glaciation, but must have followed some prior glacial condition, and that man existed in England and Northern Europe contemporaneously with extinct mammalia during inter-glacial or pre-glacial times, when the climate of England