238 THE GEOLOGICAL HISTORY OF PLANTS. 



turned to the subject in 1872, and more fully developed 

 this conclusion with reference to the Tertiary floras,* 

 and he has recently still further discussed these questions 

 in an able lecture on " Forest Geography and Archaeol- 

 ogy." f In this he puts the case so well and tersely that 

 we may quote the following sentences as a text for what 

 follows : 



"I can only say, at large, that the same species (of 

 Tertiary fossil plants) have been found all round the 

 world ; that the richest and most extensive finds are in 

 Greenland ; that they comprise most of the sorts which I 

 have spoken of, as American trees which once lived in 

 Europe — magnolias, sassafras, hickories, gum-trees, our 

 identical southern cypress (for all we can see of differ- 

 ence), and especially Sequoias, not only the two which 

 obviously answer to the two big-trees now peculiar to 

 California, but several others ; that they equally com- 

 prise trees now peculiar to Japan and China, three kinds 

 of gingko-trees, for instance, one of them not evidently 

 distinguishable from the Japan species which alone sur- 

 vives ; that we have evidence, not merely of pines and 

 maples, poplars, birches, lindens, and whatever else char- 

 acterise the temperate zone forests of our era, but also of 

 particular species of these, so like those of our own time 

 and country that we may fairly reckon them as the an- 

 cestors of several of ours. Long genealogies always deal 

 more or less in conjecture ; but we appear to be within 

 the limits of scientific inference when we announce that 

 our existing temperate trees came from the north, and 

 within the bounds of nigh probability when we claim not 

 a few of them as the originals of present species. Eemains 

 of the same plants have been found fossil in our tem- 

 perate region as well as m Europe." 



* Address to American Association. 



f "American Journal of Science," xvi., 1818. 



