In Ireland we encounter the same difficulty as in Scotland in determining how much of the glaciation of the higher mountains should be referred to land glaciers, and how much to floating ice, during submergence. The signs of glacial action have been traced by Professor Jukes to elevations of 2500 feet in the Killarney district, and to great heights in other mountainous regions; but marine shells have rarely been met with higher than 600 feet above the sea, and that chiefly in gravel, clay, and sand in Wicklow and Wexford. They are so rare in the drift east of the Wicklow mountains, that an exception to the rule, lately observed at Ballymore Eustace, by Professor Jukes, is considered as a fact of no small geological interest. The wide extent of drift of the same character, spread over large areas in Ireland, shows that the whole island was, in some part of the glacial period, an archipelago, as represented in the maps, Figures 39 and 40. Speaking of the Wexford drift, the late Professor E. Forbes states that Sir H. James found in it, together with many of the usual glacial shells, several species which are characteristic of the Crag; among others the reversed variety of Fusus antiquus, called F. contrarius, and the extinct species Nucula Cobboldiae, and Turritella incrassata. Perhaps a portion of this drift of the south of Ireland may belong to the close of the Pliocene period, and may be of a somewhat older date than the shells of the Clyde, alluded to in Chapter 13. They may also correspond still more nearly in age with the fauna of the uppermost strata of the Norwich Crag, occurring at Chillesford. [29] The scarcity of mammalian remains in the Irish drift favours the theory of its marine origin. In the superficial deposits of the whole island, I have only met with three recorded examples of the mammoth, one in the south near Dungarvan, where the bones of Elephas primigenius, two species of bear (Ursus arctos and Ursus spelaeus?), the reindeer, horse, etc., were found in a cave;* another in the centre of the island near Belturbet, in the county of Cavan. (* E. Brenan and Dr. Carte, Dublin 1859.) Perhaps the conversion into land of the bed of the glacial sea, and the immigration into the newly upheaved region of the elephant, rhinoceros, and hippopotamus, which co-existed with the fabricators of the St. Acheul flint hatchets, were events which preceded in time the elevation of the Irish drift, and the union of that island with England. Ireland may have continued for a longer time in the state of an archipelago, and was therefore for a much shorter time inhabited by the large extinct Pleistocene pachyderms.