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 winch we are not able to reply at the present moment and of 

 which the solution belongs to the future. 



