TERTIARY PLANTS. 507 



This indicates, undoubtedly, a more rapid rate of evolution at that time. 

 But it also indicates, as one cause of this rapid evolution, a migration 

 of species brought about by changes in physical geography and climate, 

 and the imposition of one fauna and flora upon another, and the ex- 

 termination or else modification of one by the other. It is difficult to 

 conceive of these sudden changes taking place otherwise. We shall 

 speak more fully of this important point under the Quaternary. 



The general character of the life-system of the Tertiary, as already 

 said, was in the main similar to the present. Nearly all the genera and 

 many of the species of plants and invertebrate animals were the same 

 as now, and the difference in aspect would hardly be recognized by the 

 popular eye ; it was certainly not greater than now exists between dif- 

 ferent countries. It is only among Mammals that the difference was 

 very conspicuous. 



Plants. 



Among plants, nearly all the genera of Dicotyls, Palms, and Grasses, 

 were the same as notv, though most of the species are extinct. The gen- 

 era were the same as notv, but not in the same localities. On the con- 

 trary, the vegetation indicated a much warmer climate than exists now 

 in the same localities. For example, if we regard the Lignitic as 

 Eocene-Tertiary, instead of Cretaceous, as do paleontological botanists 

 generally, then of more than 300 species of plants found, a very large 

 proportion were Palms, and many of them of great size ; and among the 

 Dicotyls many, like Magnolias, indicated a warm climate. Lesquereux 

 thinks the climate of Fort Union was then similar to that of Florida 

 and Lower Louisiana now. There has been a southward migration 

 of forms since that time. Again, in Eocene times there were fifteen 

 species of Palms in Europe ; and in the Tyrol the flora, according to 

 Von Ettingshausen, indicated a temperature of 74° to 81° Fahr., and 

 many of the plants are Australian in type. In the Pliocene, on the 

 contrary, many European plants were like those in America at the 

 present time. 



During the Miocene, Europe was covered with evergreens such as 

 could grow now only in the southernmost part ; and that even as far as 

 Lapland, and Iceland, and Spitzbergen. It has been estimated that the 

 Miocene flora indicates a mean temperature of 12° to 15° higher than 

 now exists in Middle Europe. In America, during the same epoch, 

 Sequoias almost identical with the Big Tree and Kedwood of Califor- 

 nia ; and Libocedrus, one of them identical with the L. decurrens of 

 California ; and Magnolias similar to the M. grandifiora of the South- 

 ern Atlantic States ; and Taxodium distichum, the cypress of the 

 swamps of Carolina and Louisiana, all existed in Greenland, and most 

 of them also in Northern Europe, and Iceland, and Spitzbergen, and 

 even Grinnell land 81° north latitude. Heer estimates the temperature 



