84 B 



Canadian Arctic Expedition, 1913-18 



also in eastern Siberia and in the Baikal mountains. Finally, if Pellaea densa 

 Hook, is also to be referred to this genus, we have a third species distributed 

 from Quebec to British Columbia. The geographical centre of the genus appears 

 thus to have been located on this continent, but south of the arctic regions. 



Typical Botrychium lanceolatum is a native of Greenland (61° N. L.) and 

 arctic Scandinavia, and also of Dovre, Herjedal, etc., but is on our continent repre- 

 sented by a variety angustisegmentum Pease and Moore. It is evidently. of 

 Scandinavian origin. The same appears also to be the case of Asplenium viride, 

 and its present southern distribution may indicate that it is one of the northern 

 plants which were left over on the southern mountains while the others retreated 

 to their northern homes. 



With regard to Isoetes echinospora, its present distribution: Iceland, Faeroe 

 Islands, Scandinavia, Denmark, and Central Europe, seems to indicate that the 

 geographical centre of this species is located in Central Europe, and that the 

 distribution to the north, to Greenland and Finmark, took place during the 

 glacial epoch. 



Dryopteris fragrans is, on the other hand, a genuine arctic type, which was 

 evidently more widely distributed in the polar regions before the glacial epoch, 

 and its occurrence in arctic Siberia, Ural, and Altai, and also in Kamtchatka, 

 might indicate a former, circumpolar distribution. 



Before we can consider the distribution in general of all the other Pteri- 

 dophyta, enumerated in Table 2, we might add the following ten species which 

 have been found in the arctic regions of Scandinavia and Russia, but not in arctic 

 America; by adding these, we shall have, I believe, an approximately complete 

 list of all the arctic Pteridophyta. The number of species is: Filices, 24; Equise- 

 taceae, 5; Lycopodiaceae, 3; Selaginellaceae, 1; and Isoetaceae, 1. 



As may be seen from these tables, most of the species have also been reported 

 from the mountains farther south; not less than 29 from America, 25 from Altai, 

 24 from the Alps and Pyrenees, 18 from Ural and Kamtchatka, and 16 from 

 Caucasus. Among these, the five species which are absent from America are: 



