208 THE GENESIS AND MIGRATIONS OF PLANTS 



America than in Europe, a fact which is itself connected with 

 the greater northward extension of this continent. 



Unfortunately the memoir containing these results was not 

 published by the Royal Society, and its publication was 

 secured in a less perfect form only in the reports of the Geo- 

 logical Survey of Canada. The part of the memoir relating 

 to Canadian fossil plants, with a portion of the theoretical de- 

 ductions, was published in a report issued in 187 1. 1 In this 

 report the following language was used : 



" In Eastern America, from the Carboniferous period on- 

 ward, the centre of plant distribution has been the Appalachian 

 chain. From this the plants and sediments extended west- 

 ward in times of elevation, and to this they receded in times 

 of depression. But this centre was non-existent before the 

 Devonian period, and the centre of this must have been to the 

 north-east, whence the great mass of older Appalachian sedi- 

 ment was derived. In the Carboniferous period there was 

 also an eastward distribution from the Appalachians, and 

 links of connection in the Atlantic bed between the floras of 

 Europe and America. In the Devonian such connection can 

 have been only far to the north-east. It is therefore in New- 

 foundland, Labrador, and Greenland that we are to look for 

 the oldest American flora, and in like manner on the border of 

 the old Scandinavian nucleus for that of Europe." 



"Again, it must have been the wide extension of the sea of 

 the Corniferous limestone that gave the last blow to the re- 

 maining flora of the Lower Devonian : and the re-elevation in 

 the middle of that epoch brought in the Appalachian ridges as 

 a new centre, and established a connection with Europe which 

 introduced the Upper Devonian and Carboniferous floras. 

 Lastly, from the comparative richness of the later Erian 2 flora 



1 " Fossil Plants of the Devonian and Upper Silurian Formations of 

 Canada," pp. 92, twenty plates. Montreal, 1871. 



9 The term Erian is used as synonymous with Devonian, and prob- 



