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THE POPULAR SCIENCE MONTHLY. 



terranean, in India, in Java ; while Sequoia is limited to the mountains 

 of California, and is to us best known through the " Big Trees" of the 

 Mariposa. 



All these genera, belonging to so many different orders, leave no 

 doubt that the vegetation of the times when these leaves were green 

 was abundant and varied. We may be sure that the genera mentioned 



Fia. 10. Sequoia disticha (Heor). 



Fig. 9. Ficus 



? x i. 



Fig. 11. Populus glandulifera (Heer), a = glanas. 



are only a few, a very few, of those to be found, that tbese were sur- 

 rounded by their congeners and by a multitude of other and different 

 forms, whose remains man has yet to see and understand. North Da- 

 kota was once, if not repeatedly, a land of forests. 



But what a strange association of leaves we have here ! the flora 

 of Florida, the flora of California, and the flora of our Northern woods. 

 As we collect the leaves, we find Sequoia associated with Jugla?is, Per- 

 sea and Ficus lie side by side, Populus and Platanus seem to affiliate, 

 although Populus has of all the widest distribution. In the beds where 

 they are found these leaves lie flat and smooth. Preserved just where 

 they fell, they seem, as they lost hold upon the parent tree, to have 

 settled once for all into quiet waters. They have never been much 

 tossed by winds nor rolled by currents, and hence can not be said to 

 indicate that these differing genera represent different altitudes. Be- 



