172 HISTORY OF THE EUROPEAN FAUNA. 



they indicated by their existence on both sides of the 

 Atlantic some ancient continuity of the coast-line. 

 He held that the line of migration of these mollusca 

 was probably from west to east, and that it must 

 have taken place during physical conditions entirely 

 different from those prevailing at present If Forbes's 

 view is correct, a current must have existed from the 

 north coast of North America along the northern 

 shore of the ancient land which stretched east as 

 far as Europe. We have also some palaeontological 

 evidence bearing on the existence of such a current 



(P- 173). 



As we shall learn presently, the early stages of 



the Glacial period were accompanied by a marine 

 transgression over Northern Russia and Germany 

 an overflow, as it were, of the waters of the Arctic 

 Ocean covering a great part of Northern Europe, 

 with the exception of Norway. One continuous 

 ocean ultimately extended from the east coast 

 of England across Holland, Northern Germany, and 

 Russia to the White Sea (Fig. 12, p. 156). The 

 south of England being at that time joined to 

 France, and Scotland to Scandinavia, there was no 

 direct communication between this large North 

 European Sea and the Atlantic. The glaciers 

 which took their origin in the Scandinavian Moun- 

 tains discharged icebergs into this sea, and many of 

 them no doubt were stranded on the east coast of 

 England. The boulders of Scandinavian origin which 

 have been discovered in recent geological deposits on 



