The vast abundance also of the mammalia in the caves of South Wales and Somerset, and their presence in the Island of Caldy, and it may be added in Ireland, can only be accounted for by the elevation of the present sea-bottom, so as to allow of their migration over plains covered with abundant pasture. It seems, therefore, to me that the accompanying map, Fig. 126, represents with tolerable accuracy the ancient coast-line of Britain, and of the adjacent parts of the continent in the pleistocene age. The fertile valleys of the English Channel, Bristol Channel, and the German Ocean, would afford sustenance to a large and varied fauna, and numerous herbivores, such as the reindeer, bison, and horse, would supply food to the palæolithic hunters, who followed them in their annual migrations. And it must be remarked on this hypothesis, that the valley of the Garonne would offer a free passage both to the animals and to the hunters of Auvergne down to the prairie, extending as far as the 100-fathom line off the French coast, and that the hunting grounds would reach to Devonshire and Somerset without any barrier except that offered by the rivers. It is therefore no wonder that the implements in the caves of Kent’s Hole, Wookey Hole, and the South of France, should be of the same type. _Distribution of Palæolithic Implements in this Area._ This geographical configuration in pleistocene times may perhaps account for the distribution of the palæolithic implements in the river gravels. The Seine and the Somme debouch into the same valley as the rivers of the south of England, and the Straits of Dover mark the position of a low watershed leading into the valley of the German Ocean, on the sides of which, in the eastern counties, river-bed implements are so numerous. These are of the same type in northern France, Sussex, Hampshire, Kent, and as far north as the Wash; and were therefore used by the same race of men. The difference between them and those of the cave-dwellers in the south and west, may be due to their possessors occupying different hunting grounds. Each tribe of American Indians at the present time has its own territory for hunting, which is jealously guarded against encroachment, and in which the articles peculiar to the tribe are being accumulated in the refuse-heaps, while other sets are being accumulated in other districts. If we suppose that the palæolithic savages divided up their hunting grounds in this manner, the difference which exists between the implements of the river-beds and caves may be readily explained, as well as their being found for the most part in different areas. The pleistocene climate in the area north of the Alps and Pyrenees will be treated in the eleventh chapter, after the examination of the cave-fauna of southern Europe. CHAPTER X. THE FAUNA OF THE CAVES OF SOUTHERN EUROPE AND THE EVIDENCE AS TO THE MEDITERRANEAN COAST-LINE IN THE PLEISTOCENE AGE.