A Mountain Tulip. 187 



But as the cold began to subside, and as a warmer 

 fauna and flora invaded the now milder plains and 

 valleys of central Europe, the glacial types, being less 

 adapted to the new conditions, began to retreat north- 

 ward towards the Arctic Circle, or upward towards the 

 chilly summits of the principal mountains. Slowly, 

 age after age, the southern plants and animals overran 

 all the. lower portions of the continent, cutting the 

 glacial fauna and flora in two, and established them- 

 selves as far as the outlying peninsula of Britain, 

 which still continued to form an integral part of the 

 European mainland. After most of the Germanic 

 types had made good their foothold even in this <^is- 

 tant region, however, and after the still more southern 

 poeonies of the Steep Holme and the rock-cistus of 

 Torquay had established themselves under the lee of 

 the Cornish and Kerry mountains, on 'the Submerged 

 tract which then stretched out far to the west of the 

 Scilly Islands, the land began to sink slowly toward 

 isea-level ; and at last an arm of the Atlantic encir- 

 cled the whole of Ireland, and sttll later the waters of 

 two long gulfs which now form the English Channel 

 and the North Sea met tc^ether by bursting through 

 the narrow barrier of chalk between Dover and Cape 

 Blancnez. Thus Britain finally became an island 

 group ; and, being washed on three sides by the warm 



