Rhine; the English Channel was not yet in being, and Britain existed only as part of a continent which stretched away uninterruptedly northward towards the Arctic circle. It thus appears that the advent of man in Northern Europe is assignable to a period when the mammoth and the tichorine rhinoceros still roamed its forests, and the great cave-tiger and other extinct carnivora haunted its caverns; when the gigantic Irish elk, the reindeer, the musk-ox, and the wild horse were objects of the chase; and the hippopotamus major was a summer visitor to the Seine and the Thames. When first employing the term _prehistoric_ which has since obtained such universal acceptance, I remarked, in reference to Scottish aboriginal traces: “There is one certain point in this inquiry into primitive arts which the British antiquary possesses over all others, and from whence he can start without fear of error. From our insular position it is unquestionable that the first colonist of the British Isles must have been able to construct some kind of boat, and have possessed sufficient knowledge of navigation to steer his course through the open sea.”[12] It then seemed a postulate on which the most cautious adventurer into the great darkness which lies behind us might confidently take his stand. But the point was no certain one after all. The fauna of the later Elephantine period still roamed over a wide continent unbroken by the English Channel or the Irish Sea; and the valley of the Rhine stretching northward through the still unsubmerged plain of the German Ocean, received as tributaries the Thames and the Humber, perhaps also the Tweed and the Forth. Measured therefore by the most moderate estimate of geological chronology, the historical period is, in relation to the interval since the first appearance of man, somewhat in a ratio with the superficial soil and vegetable mould, as compared with the whole deposits of the stratified drift: in other words, it is so insignificant as, in a geological point of view, to be scarcely worth taking into account. Whatever be the consequences involved in such comprehensive inductions, proofs appear to accumulate, with every renewed search, of the wide diffusion throughout the bone-bearing drift of the post-glacial period, of symmetrically-formed flints, bearing indubitable traces of intelligence and primitive mechanical skill.