DISTRIBUTION OF BRITISH PLANTS. 335 



of this intermediate land, as was said before, said to have 

 been prior to the glacial epoch, but its destruction is like- 

 wise supposed to have taken place before that period. 



Additional reasons for believing this part of the Irish 

 flora to have migrated over land are afforded ; first, by the 

 fact that the few species (not amounting to twenty) which 

 compose this flora are all members of families whose seeds 

 are not well adapted for flight through the air ; and, secondly, 

 by the circumstance that no marine currents set in such a 

 direction as to have conveyed them by water to the coast of 

 Ireland. <{ The remarkable point concerning these plants is, 

 that they are all species which at present are forms either 

 peculiar to, or abundant in, the great peninsula of Spain 

 and Portugal, and especially in Asturias. The probability 

 of the ancient existence of a land extending far into the 

 Atlantic is further borne out by the fact that the flowers of 

 the groups of islands between the Gulf-weed bank and the 

 mainland of the Old World are all members of one flora." 



These changes in the relative position of sea and dry 

 land, which were probably gradual, and effected during the 

 course of long ages, are all dated by geologists, it must 

 be remembered, as previous to the time when man became 

 an inhabitant of the globe, when the period called "the 



