Whatever may have been the precise relation of the Pleistocene period to the Great Ice Age--a point as to which there is some difference of opinion--it is admitted that at some time or other after that when the hyena howled in the Brixham Cave, and when Palæolithic man left there his rudely worked flint implements, the conditions of life in Northern Europe changed. The Arctic zone invaded the larger part of the Temperate zone, and a great cap of ice covered not only the Scandinavian countries and the greater part of Russia but Ireland, Scotland and England, at least as far south as the valley of the Thames. Now were our chalk hills rounded into smoothness, now were many of our river beds hollowed out, and untidy heaps of “terminal moraine” deposited where the glaciers debouched into the valleys. This dismal change, destructive of all the higher organic life and continuing possibly over a period of thousands of years, makes, in our island at any rate, an impassable barrier between two races of mankind. When the great ice deluge subsided, when the winter-tyrant returned to his true Arctic home, when the oak and the pine began again to appear upon the hills, and flowers like our own bloomed in the valleys, then the Neolithic man, the “New Stone-worker,” came upon the scene and scattered abundant evidences of his presence over the land. From that period--date we cannot call it, for we have no evidence which would justify us in making the roughest approximation to a date--man has been continuously a dweller in this island, Neolithic man at length yielding ground to the immigrant Celt, the Celt to the Saxon, the Saxon to the Dane and the Norman.