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
|Fig. 9.—Ficus ———? x 2||Fig. 10. Sequoia disticha(Heer).|
|Fig. 11.—Populus glandulifera (Heer), a glands.|
are only a few, a very few, of those to be found, that these were surrounded by their congeners and by a multitude of other and different forms, whose remains man has yet to see and understand. North Dakota 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 Juglans, Persea 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-