. Studies in fossil botany . Paleobotany. 198 STUDIES IN FOSSIL BOTANY the megasporangium is enclosed in an integument, which in Miadesmia, however, completely roofs in the sporan- gium above, leaving only a narrow opening or micropyle at the distal end (Figs. 83 and 84). The integument is provided with long tentacles, which, as they project beyond the micropyle, may probably have assisted pollination. The sporangial wall is less developed than in Lepidocarpon, the integument having, as it appears,. Fig. 83.—Miadesmia. jiicmbranacca. Approximately transverse section of seed-like organ. /, /, l
. Studies in fossil botany . Paleobotany. 198 STUDIES IN FOSSIL BOTANY the megasporangium is enclosed in an integument, which in Miadesmia, however, completely roofs in the sporan- gium above, leaving only a narrow opening or micropyle at the distal end (Figs. 83 and 84). The integument is provided with long tentacles, which, as they project beyond the micropyle, may probably have assisted pollination. The sporangial wall is less developed than in Lepidocarpon, the integument having, as it appears,. Fig. 83.—Miadesmia. jiicmbranacca. Approximately transverse section of seed-like organ. /, /, lamina of sporophyll; , vascular bundle ; v, velum or integument; lg, ligule; sm, sporangium-wall; m, membrane of megaspore. X about 30. R. S. S. Coll. 2237. more completely taken over the function of a protective organ, and no abortive sister-cells of the single megaspore (in which the prothallus is sometimes present) have been observed. Thus the seed-like character is even more striking in Miadesmia than in Lepidocarpon. There seems to be no near affinity between the two genera, which differ widely, especially in the insertion of the sporangium and the position of the micropyle, and in each of which, presumably, the seed-habit was independently 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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