344 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
I must now bring to-a close my review of the ancient plant-bearing 
beds of the Arctic regions. We may conclude that in the greater 
number of cases it is evident that the plants really grew in the 
regions in question. Although we know of fossil plants in some 
marine deposits, as, for instance, in the Senonian of Greenland and 
perhaps also in the Trias of Spitzbergen, these are exceptions which 
lack importance, since other deposits of a closely corresponding age 
are of fresh-water origin. While it may be admitted that even in 
Spitsbergen part of the Tertiary flora may have been transported 
from a more or less distant country by a river, yet other deposits on 
approximately the same horizon indicate that the greater number of 
the species, and among them the most important types, have actually 
flourished in the region itself. 
Taking into account the facts which I have enumerated, it is evi- 
dent that the fossil floras of the Arctic should be still regarded as the 
foundation of every discussion of the former climates of that region. 
How are these favorable climates to be explained? That is a ques- 
tion to which we are not able to reply at the present moment and of 
which the solution belongs to the future. 
