. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. 548 VEGETATION OF THE DEVONIAN PERIOD. [Ch. XXVI Fig. 618. Psilophyton princeps. Dawson, Geol. Quart. Journ., vol. xv., 1863; and Canada Survey, 1863. Species characteristic of the whole Devonian period in North America. A. Psilophyton princeps, plant restored by Dawson. /. Stem, twice natural size. A&. Ehizome, or underground root-like stem. g. Termination of branches. Ac. Cylindrical rootlets. h. Crozier-like, or circinate vernation. d. Ehizome. i. Fructificati
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. 548 VEGETATION OF THE DEVONIAN PERIOD. [Ch. XXVI Fig. 618. Psilophyton princeps. Dawson, Geol. Quart. Journ., vol. xv., 1863; and Canada Survey, 1863. Species characteristic of the whole Devonian period in North America. A. Psilophyton princeps, plant restored by Dawson. /. Stem, twice natural size. A&. Ehizome, or underground root-like stem. g. Termination of branches. Ac. Cylindrical rootlets. h. Crozier-like, or circinate vernation. d. Ehizome. i. Fructification. e. Areole of rhizome. gen; but with this single exception the American Devonian flora affords, like the Carboniferous, no evidence of the existence of plants of higher organization than the gymnosperms. The monotonous character of the Carboniferous flora might be ex- plained by imagining that we have only the vegetation handed down to us of one set of stations, consisting of wide swampy flats. But Dr. Dawson supposes that the geographical conditions under which the Devonian plants grew were more varied, and had more of an up- land character. If so, the limitation of a flora represented by so many genera and species to the gymnospermous and cryptogamous orders, and the absence of plants of higher grade, admit of no expla-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lyell, Charles, Sir, 1797-1875. New York, D. Appleton and co.
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