The pictorial sketch-book of Pennsylvania : or, its scenery, internal improvements, resources, and agriculture, popularly described . ding the growth of the vegetable matter, it is neces-sary to institute some further inquiries. Thus, by comparisons withexisting species, and the elements constituting their growth, we obtainconsiderable light on the subject, and are able to form conclusionswhich could not otherwise be safely arrived at. We shall append afew illustrations. The Sigillaria, so numerous in the coal, have gen-erally been classed as monocotyledonous plants; but late observerscontend
The pictorial sketch-book of Pennsylvania : or, its scenery, internal improvements, resources, and agriculture, popularly described . ding the growth of the vegetable matter, it is neces-sary to institute some further inquiries. Thus, by comparisons withexisting species, and the elements constituting their growth, we obtainconsiderable light on the subject, and are able to form conclusionswhich could not otherwise be safely arrived at. We shall append afew illustrations. The Sigillaria, so numerous in the coal, have gen-erally been classed as monocotyledonous plants; but late observerscontend that they properly belong to the dicotyledonous irregular and longitudinal furrows of the surface of the stems—their swelling out at the base, angle of dip or downward directionof the roots, are characters constantly observable in the dicotyledon-ous, but never in monocotyledonous plants. Besides, these trees havea separable bark; and slices of it, prepared for microscopic investiga-tion, have exhibited traces of medullary rays, which are universallyrecognized as proofs of dicotyledonous structure. While they are. FIG. 10.—CATJLOPTERIS
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Keywords: ., bookcentury1800, bookdecade, booksubjectminesandmineralresources
