DISTRIBUTION OF BRITISH PLANTS. 333 



land and of Ireland are thought to have remained " in all 

 probability unsubmerged during the glacial epoch, they may 

 have come over either before, or during, or after that period. 

 There are strong reasons for believing they migrated before."" 



At a subsequent period to the introduction of the four 

 floras already mentioned, they became isolated by a fresh 

 remodelling of sea and land, when the formation of the 

 English Channel separated England from Prance, and cut 

 off the flowers which had travelled thence from their original 

 connections ; when also the other coasts of England were 

 shaped by the formation of the German Ocean, which sepa- 

 rated it from the rest of the Continent ; and, by the recon- 

 version of land into sea, by which it was separated from 

 Ireland, the Irish Sea being " scooped out " of the dry and 

 choked-up bed of the old glacial sea. 



But much older than any of these floras is that one sup- 

 posed to be, which characterizes the mountainous districts 

 of the west and south-west of Ireland, and corresponds, as 

 we are told, with that of the north of Spain. By Professor 

 Forbes' s theory, there was at an ancient period (anterior to 

 that of any of the floras already considered) a close approxi- 

 mation, if not a connection, of Ireland with Spain; which is 

 a startling suggestion when we remember the immense dis- 



