THE ARCTIC FAUNA. 145 



light, many of which are identical with those found 

 in Greenland ; and some of the Greenland forms 

 (such as Taxodium distichum and Sequoia Langsdorfii) 

 have been found too in Alaska, showing that there 

 was probably a continuity of land between Spits- 

 bergen and North America by way of Greenland. 

 Two species of Sequoias, namely, S. sempervirens 

 and 5. gigantea, the well-known Californian giant 

 trees, are very closely allied to the Greenland forms 

 discovered by Professor Heer. 



Heer assigned the Arctic plant-bearing beds to the 

 Miocene epoch, but doubts have been recently thrown 

 upon this opinion by Mr. Starkie Gardner, who 

 brought forward arguments in support of his theory 

 of their being of the Eocene age. Professor Heer, 

 however, was able to meet these criticisms, and he is 

 ably supported in his views by Professor Engler and 

 other eminent continental botanists. 



It is evident that under the present conditions of 

 temperature none of those plants could have flourished 

 in Greenland. The climate must have been much 

 milder than it is at present. Professor Heer estimated 

 from the general aspect of the fossil flora that the 

 mean annual temperature of North Greenland was 

 at least nine degrees centigrade, and that the mean 

 winter temperature was not below zero. 



It will hardly be necessary for me to review here 

 the various theories which have been advanced by 

 geologists and botanists to account for this remark- 

 ably high temperature in such northern latitudes 



JO 



