l888-1902.No.il.] LICHENS. 51 



Notes on the systematic list. 



The foregoing list shows that the district, which includes Arctic 

 America, Greenland, Spitsbergen and Iceland, has about 500 lichens re- 

 corded for it. I have no doubt that more will still be found. My in- 

 clusion of the lichens of Greenland, Spitsbergen and Iceland in a list 

 of those brought back by the Second Norwegian Expedition to Arctic 

 America is, I consider justified. The enumeration of lichens given above 

 will thus give us a fairly complete picture of the lichen-vegetation of 

 Ellesmere Land and King Oscar Land. 



To show in what relation the lichen-floras of these four districts 

 stand to one another I have compiled a few statistical notes, comparing 

 the lichens found in Arctic America, Greenland, Spitsbergen and Iceland. 



This list enumerates a total of 495 arctic lichens. Of these there 

 have been recorded for 



Arctic America 253 or 51.1 /o 



Greenland 338 or 68.2 - 



Spitsbergen 206 or 41.6 - 



Iceland 254 or 51.3 - 



It must be mentioned also that of this total of 495 lichens we have 

 recorded as occurring in 



Arctic America only .... 57 or 11.5 / species 



Greenland only . . ... 77 or 15.5 - 



Spitsbergen only . . . . . 33 or 6.6 - 



Iceland only 37 or 7.4 - 



Only 84 or 16.9 % of the total of 495 lichens are found to be com- 

 mon to Arctic America, Greenland, Spitsbergen and Iceland. 204 or 

 41.2/ of the total are confined to one only of the four districts. It 

 would have been possible and very interesting to compare with this the 

 lichens of Alaska or the temperate parts of America, but I have rather, 



