NOTES TO BOOK XVIII. 693 



offered a great body of very striking and converging rea 7 

 sons, the present vegetable and animal population of the 

 British Isles is to be accounted for by the following series 

 of events. The marine deposits of the meiocene formation 

 were elevated into a great Atlantic continent, yet separate 

 from what is now America, and having its western shore 

 where now the great semicircular belt of gulf-weed ranges 

 from the 15th to the 45th parallel of latitude. This con- 

 tinent then became stocked with life, and of its vegetable 

 population, the flora of the west of Ireland, which has many 

 points in common with the flora of Spain and the Atlantic 

 islands (the Asturian flora), is the record. The region 

 between Spain and Ireland, and the rest of this meiocene 

 continent, was destroyed by some geological movement, but 

 there were left traces of the connexion which still remain. 

 Eastwards of the flora just mentioned, there is a flora 

 common to Devon and Cornwall, to the south-east part of 

 Ireland, the Channel Isles, and tfre adjacent provinces of 

 France ; a flora passing to southern character ; and 

 having its course marked by the remains of a great rocky 

 barrier, the destruction of which probably took place ante- 

 rior to the formation of the narrower part of the channel. 

 Eastward from this Devon or Norman flora, again, we have 

 the Kentish flora, which is an extension of the flora of 

 North-western France, insulated by the breach which 

 formed the straits of Dover. Then came the Glacial 

 period, when the east of England and the north of Europe 

 were submerged, the northern drift was distributed, and 

 England was reduced to a chain of islands or ridges, 

 formed by the mountains of Wales, Cumberland, and Scot- 

 land, which were connected with the land of Scandinavia. 

 This was the period of glaciers, of the dispersion of boulders, 



