52 OTTO V. DARBISHIRE. [SEC. ARCT, EXP. FRAM 
lower down, taken Germany and the Tirol as objects for comparison. 
To this matter I will refer directly. 
On a former occasion, in discussing the lichen-flora of Greenland, 
I pointed out the remarkable likeness of the flora of Greenland to that 
of Germany. Of 286 lichens recorded for Greenland up to that date, 
namely 1897, 213 occured in Germany. Of these 
105 or 49.4 %o were purely alpine, 
11 or 5.1 - preferred alpine situations, 
97 or 45 - were common to the hill and the plain. 
That is to say of the Greenland species found in Germany 54.5 °/, 
were found to be mainly alpine, but all practically had been recorded 
from the hills. Another point of interest was referred to in the paper 
on Greenland lichens. Of the 171 crustaceous lichens recorded from 
Greenland 110 or 64.3 °/, were recorded from Germany, of the foliace- 
ous lichens 60 or 85.7 °/o, and of the fruticulose lichens 34 or 94.4 °/, 
These figures were explained by reference to the advance and the 
final retreat of the ice after the last ice-age. During the greatest ex- 
tension of the ice in the ice-age the lichens would be pushed well to the 
south and into the plains. When the ice retreated however they would 
pass up to the north and into the hills, into the colder zones and 
regions. The warmer strips of land intervening would then separate 
the alpine and the northern lichen-floras. 
The oldest forms, the fruticulose lichens, would go back to the times 
when the alpine and northern floras were still united. We find there- 
fore that 94.4 °/) of the Greenland fruticulose lichens are found in Ger- 
many, of which however not a few are found in the plains. Of the less 
highly differentiated crustaceous lichens which must be considered to be 
of more recent development only 64.3 °/) are common to Germany and 
Greenland. I would like to say that I consider it not unlikely that a 
number of these crustaceous species are really species alike in their ex- 
ternal morphology only and that they are not really related to one 
another otherwise. We may call a Greenland plant by the same name 
as the German one, and as far as we are able to judge we may be 
Justified in so doing. At the some time the two plants may have heen 
separately derived though from some common ancestor. Some of the 
higher fruticulose species seem never to vary, whereas the variations 
among the simpler crustaceous species are at the best most puzzling and 
of frequent occurrence. 
The following tables are based on the list of 495 lichens enumerated 
above. They confirm the views already expressed: 
