. Studies in fossil botany . Paleobotany. 176 STUDIES IN FOSSIL BOTANY sions; where the external surface is perfect, it is completely invested by the overlapping laminae of the sporophylls, which are closely packed together (Fig. 70). When the preservation is less complete, the free tips of the laminae have perished, leaving only their more solid basal portions, which often assume a hexagonal form from mutual pressure. The fractures of the casts often show something of the internal organ- isation,the tissues being preserved to some ex- tent, though in a car- bonised condition (Fig. 70). It is
. Studies in fossil botany . Paleobotany. 176 STUDIES IN FOSSIL BOTANY sions; where the external surface is perfect, it is completely invested by the overlapping laminae of the sporophylls, which are closely packed together (Fig. 70). When the preservation is less complete, the free tips of the laminae have perished, leaving only their more solid basal portions, which often assume a hexagonal form from mutual pressure. The fractures of the casts often show something of the internal organ- isation,the tissues being preserved to some ex- tent, though in a car- bonised condition (Fig. 70). It is only, how- sm ever, in the petrified sph specimens that the structure is completely revealed Yw,.—Lepidostrobus. Diagram of heterosporous cone in radial section, ax, axis; s£h, sporo- Our more detailed phylls; sm, sporangia, seated singly on the . upper surface of each sporophyll; lg, ligules ; description will be the microsporangia, in upper part of cone, con- U J r j tain numerous microspores, while the mega- Dase(l on a IOrm named sporangia below are shown containing four U,, Wf'lKamc^n T „,A„- megaspores each. () W W1|UamS0n Lepl- dostrobus oldhamius} of which several examples in a calcified state have been yielded by the calcareous nodules of the English Coal- measures. The largest specimens of this strobilus reach a diameter of about 4 cm. ; the axis is slender, about 4 or 5 mm. in thickness. The anatomical structure is of the usual Lepidodendroid type. The centre of 1 For a full illustrated account of the organisation of these cones, see Maslen, " Structure of Lepidostrofois," Traits. Linn. Soc. vol. v. 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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