50 NOTES OX BOTANY. 



parts of Europe. But our higher mountain summits yield us a 

 very interesting group of plants, which are not Germanic, but 

 Scandinavian in their extra-Britannic distribution.- These Scandi- 

 navian species would come next to the Germanic in point of 

 number. There were still, in Forbes' opinion, three small 

 assemblages to be accounted for, one of these being situated in the 

 south-east of England (Kent), another in the south-west of England 

 and the south-east of Ireland, and the third in the south-west of 

 Ireland. 



How are we to account for these facts ; this particular grouping 

 of plants within our area? The question is one of wonderful 

 interest, and I think that it has not yet found an altogether satis- 

 factory solution. Forbes' theory was ingenious, and I may, 

 perhaps, be allowed to refresh your memories by a brief resum/i. 



The great mass of the British Flora, as well as of the pulmo- 

 niferous mollusca, being Germanic, Forbes shewed that it had 

 migrated from the Continent during the post-pliocene period, after 

 the bed of the glacial sea had been elevated so as to form a land- 

 passage between England and the Continent. Naturally the species 

 of this type are most numerous in our eastern counties, and thin 

 out gradually as we proceed westward. 



But though the migration of plants and animals over the great 

 Germanic plain accounted for the major part of our British species, 

 there was still a considerable Flora, and a portion of our Fauna, 

 which could not be traced to such a source, seeing that they are 

 inhabitants, not of the ancient west of Europe, but of Scandinavia. 

 These Alpine species could not have found their way to us after the 

 Germanic forms, for their areas had then become isolated on 

 mountain ranges. Geological evidence clearly showed that the 

 central and northern parts of the British Isles, along with the 

 Germanic plain, had at one time been covered with an Arctic Fauna 

 and Flora. This was the glacial period, when an intense cold 

 prevailed over central and northern Europe. During a part of this 

 era Forbes maintained that our mountains rose above the sea as 

 scattered islets, having a northern vegetation, and that as the land 



