. Studies in fossil botany . Paleobotany. 54 STUDIES IN FOSSIL BOTANY placed, surrounds the stalk of each peltate scale (see Fig. 21). The sporangia are elongated sacs, stretching back from the lamina to the axis (Figs. 18 and 20). The sporangial wall, as preserved, is usually only one cell thick, and the lateral membranes of its cells are stiffened by projecting ridges (Fig. 22). When cut across, these. Fig. -zo.—Calamostachys Binneyana. A single peltate sporangiophore, in longitudinal section, sin, sporangia, attached at a to the edges of the peltate lamina. They are full of spore-tetrads. X
. Studies in fossil botany . Paleobotany. 54 STUDIES IN FOSSIL BOTANY placed, surrounds the stalk of each peltate scale (see Fig. 21). The sporangia are elongated sacs, stretching back from the lamina to the axis (Figs. 18 and 20). The sporangial wall, as preserved, is usually only one cell thick, and the lateral membranes of its cells are stiffened by projecting ridges (Fig. 22). When cut across, these. Fig. -zo.—Calamostachys Binneyana. A single peltate sporangiophore, in longitudinal section, sin, sporangia, attached at a to the edges of the peltate lamina. They are full of spore-tetrads. X about 40. S. Coll. 174. (G. T. G.) buttresses are not easily distinguished from the cell- walls. In Calamostachys Binneyana the spores are very numerous in each sporangium, and, so far as has been ascertained, were all of one kind, the average diameter of the full-grown spores being about .09 mm. Curiously enough, we often find them united in groups of four, the tetrad being still enclosed within the membrane of its mother-cell (see Fig. 22, A, B, C). Hence we see that. 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 Scott, Dukinfield Henry, 1854-1934. London, A. and C. Black
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