24:0 THE GEOLOGICAL HISTORY OF PLANTS. 



The memoir containing these results was not published 

 by the Koyal Society, but its publication was secured in a 

 less complete form in the reports of the "Geological Sur- 

 vey of Canada. " The part of the memoir relating to Cana- 

 dian fossil plants, with a portion of the theoretical deduc- 

 tions, was published in a report issued in 1871.* In this 

 report the following language was used : 



" In eastern America, from the Carboniferous period 

 onward, the centre of plant distribution has been" the Ap- 

 palachian chain. From this the plants and sediments 

 extended westward 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 for 

 this must have been to the northeast, whence the great 

 mass of older Appalachian sediment was derived. In the 

 Carboniferous period there was also an eastward distribu- 

 tion from the Appalachians, and links of connection in 

 the Atlantic bed between the floras of Europe and Ameri- 

 ca. In the Devonian such connection can have been only 

 far to the northeast. It is therefore in Newfoundland, 

 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 remaining 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 f flora in eastern 

 America, especially in the St. John beds, it might be a 



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

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

 f See pages 107 and 108. 



