362 THE CANADIAN NATURALIST. [June 



the flora of the Arctic American islands, and but one to that of 

 Arctic Greenland. The Lapponian region is, of course, as well 

 known as any on the globe ; but further east, and especially in 

 Arctic Siberia, much remains to be done; not perhaps in the 

 discovery of new plants, but in ascertaining the southern limits of 

 various Siberian ones that probably cross the arctic circle. Of 

 Arctic Continental America the same may be said. 



The method which I adopted in finally arranging the materials 

 for geographical purposes was the following. I took Wahlenberg's 

 1 Flora Lapponica,' Fries's ' Summa Vegetabilium Scandinavise,' 

 Ledebour's ' Flora Rossica,' Hooker's ' Flora Boreali-Americani,' 

 and Lange's ' Plants of East Greenland,' which together embrace 

 in outline almost everything we know of arctic botany, geographi- 

 cal, systematic, and descriptive. I put together from these all 

 the matter they contained, and arranged it both botanically and 

 geographically into a ' Systema,' which I studied with an 

 Admiralty north circumpolar chart ; and by this means arrived at 

 a general idea of the position and extent of the centres of 

 vegetation within the polar circle. I then again went through the 

 catalogue with the herbarium, with every work treating on arctic 

 plants that was accessible to me, and lastly revised it, verifying 

 the habitats, comparing specimens from each province, adding new 

 localities from more recent floras, catalogues, and voyages ; tracing 

 the extra-arctic distribution of the species, and noting all points 

 requiring further investigation. 



(To be continued,') 



NOTICES OF SOME REMARKABLE GENERA OF 

 PLANTS OF THE COAL FORMATION. 



By J. W. Dawson, LL.D., F.R.S., etc.* 



Genus Siqillaria. — The Sigillariae, so named from the seal- 

 like scars of fallen leaves stamped on their bark, were the most 

 important of all the trees of the coal-swamps, and those which 

 contributed most largely to the production of coal. Let us take 

 as an example of them a species very common at the Joggins, and 

 which I have named S. Broumii, in honour of my friend, Mr. R. 



* From " Acadian Geology," 2nd edition, with specimens of the 

 illustrations. 



