Field Note. 371 



that temperate plants, at least, did not survive the rigours of 

 the Ice Age, and there must have been a re-immigration of 

 these types, therefore, in post-glacial times. 



By whatever means those temperate plants (about 270 

 species) of our Flora, which occur only in England, reached 

 Britain, it is clear from the map that their headquarters are 

 in France, while in England they are most abundant in the 

 south and south-east counties, gradually thinning out as we 

 move north and north-west. This seems to indicate the main 

 lines of migration followed by the bulk of our temperate 

 Flora. Similar conditions seem to have affected the migra- 

 tion of about seventy species which have reached England 

 and Ireland, but which are absent from Scotland. On the 

 other hand, the distribution of over a hundred species confined 

 to England and Scotland indicates a co-mingling of southern 

 and northern types. About 40 of these species are found in 

 Scotland and in the north of England, but are absent from 

 south and south-east England. These boreal types may have 

 migrated more from east to west, rather than from south to 

 north. This may help to explain their greater prevalence in 

 north Britain, although the possibility of their having been 

 exterminated in the south during or since the incoming of a 

 southern temperate flora has to be considered. 



Sixty species confined to Scotland represent probably the 

 oldest portion of our Flora. Whether they survived the Ice 

 Age on ' Nunataks,' or reached their present stations after the 

 retreat of the ice, they are best regarded as relics of that old 

 palaearctic Flora which girdles the globe within the Arctic 

 Circle, but which, during the period of maximum glaciation, 

 was driven southwards in every longitude. 



Calopteryx virgo Linn, in Cumberland. — In my paper 

 on the Dragonfly fauna of Cumberland [The Naturalist, 1917, 

 PP- 357"358), I regarded this species as a local and somewhat 

 scarce insect. It was not until the present season that I met 

 with it again, when, on May 25th, I saw quite a number on 

 the banks of the River Eden between Warwick Bridge and 

 Wetheral. The flight of C. virgo is not strong, but I was not 

 able to capture more than three specimens, the river at that 

 point being overhung with trees, the low, spreading branches 

 of which interfered with the use of the net. These are all 

 males, and the wings are of the smoky brown colour usual in 

 immature examples, as was to be expected from the somewhat 

 early date. My previous Cumberland captures were in late 

 June and early July.. — F. H. D.ay, Carlisle, 12th September, 

 1921. 



1921 Nov. l- 



