Page:Early Man in Britain and His Place in the Tertiary Period.djvu/50

22 chapter. Mr. Starkie Gardner places the land barrier which shut off the Atlantic from the Arctic Sea, between the 60th and 70th degrees of N. latitude, or in the position in which it is represented in the accompanying map (Fig. 3).

The forms of animal life also common to Britain and America prove a connection between the two regions in the Eocene age. The opossum of Eocene Britain, the extinct Coryphodon, Lophiodon, Anchithere, and Anoplothere, are common to both, and the alligator, which haunted the rivers of the south of England, the bony pike, the last representative of the armour-clad fishes of the Secondary period, and a little snail (Helix labyrinthica), have found a refuge in America from those agencies by which they have been exterminated in Europe.

For the migration of these animals there must have been a continuous tract of land between Britain and America; and the direction of this is pointed out by the soundings in the Atlantic and the Northern seas (see Map, Fig. 3). It is indicated by the ridge of land at a depth of 500 fathoms sweeping away northwards from the west of Ireland, past the Faroe Islands to the south of Iceland and Greenland. On the eastern side of this the observations taken in the Norwegian Deep Sea Expedition in 1877 prove the existence of deep water between Jan Mayen Land and Spitzbergen, and between that