17 



APPENDIX. 



The five separate floras which Forbes, in the essay referred to, 

 regarded as making up our phaanogamic vegetation are as 

 follows : — 



1. An Asturian flora, confined to the mountainous districts of 

 the south and west of Ireland, connected by the presence of 

 certain prevalent species with that of the mountains of Asturias, 

 in Spain. From these latter it was evidently derived through 

 migration over a great mountain barrier, which once extended 

 from the West Pyrenees to Ireland. Its southern alpine cha- 

 racter, so distinct from that of the mountains of Wales and Scot- 

 land, its limitation and isolation, are so many evidences of its 

 antiquity, and serve to mark it out as the oldest of the floras 

 now comprising our vegetation. 2. An Amorican Flora, in the 

 S.W. of England and S.E. of Ireland, intimately related to that 

 of the Channel Islands, and the opposite coast of France in 

 Brittany and Normandy. Its distribution depended on the 

 subsequent existence of a barrier from the N.W. of France to 

 the S.W. of England, and thence to Ireland, across which it was 

 conveyed. This is in all probability the second oldest flora, 

 and its separation from the parent centre, seems to have 

 resulted from the destruction of the Atlantic barrier, having led 

 to the destruction of this one also, though remains of it still 

 exist in the various islands of the channel. 3. A Belgic Flora 

 in the S.E. of England, where the cretaceous system of rocks is 

 chiefly developed, in which many species occur which are 

 common to this and the opposite districts of France. It was 

 afterwards introduced at a period when the N.E. coast of France 

 and the S.E. coast of England were united, and formed portions 

 of the same area, though it has since partially extended itself 

 into other formations than the cretaceous. 4. A Boreal Flora, 

 found principally on the higher mountains of Scotland, and par- 

 tially on those of N. England and Wales, which is closely allied 



