230 DARWINIAN A. 



upon the ground which they now, after much vicissi- 

 tude, scantily occupy. 



Differences of climate, or circumstances of migra- 

 tion, or both, must have determined the survival of 

 Sequoia upon the Pacific, and of Taxodium upon the 

 Atlantic coast. And still the redwoods will not stand 

 in the east, nor could our Taxodium find a congenial 

 station in California. Both have probably had their 

 opportunity in the olden time, and failed. 



As to the remaining near relative of Sequoia, the 

 Chinese Glyptostrobus, a species of it, and its verita- 

 ble representative, was contemporaneous with Sequoia 

 and Taxodium, not only in temperate Europe, but 

 throughout the arctic regions from Greenland to 

 Alaska. According to Newberry, it was abundantly 

 represented in the miocene flora of the temperate zone 

 of our own continent, from Nebraska to the Pacific. 



Very similar would seem to have been the fate of 

 a more familiar gymnospermous tree, the Gingko or 

 Salisburia. It is now indigenous to Japan only. Its 

 ancestor, as we may fairly call it since, according to 

 Ileer, " it corresponds so entirely with the living spe- 

 cies that it can scarcely be separated from it " once 

 inhabited Northern Europe and the whole arctic re- 

 gion round to Alaska, and had even a representative 

 farther south, in our Rocky Mountain district. For 

 some reason, this and Glyptostrobus survive only on 

 the shores of Eastern Asia. 



Libocedrus, on the other hand, appears to have 

 cast in its lot with the Sequoias. Two species, ac- 

 cording to Ileer, were with them in Spitzbergen. L. 

 decurrens, the incense cedar, is one of the noblest 



