. Studies in fossil botany . Paleobotany. SIGILLARIA 227 tions of the primary zone. This latter character may- serve to distinguish a Sigillaria from a Lepidodendron, but too much stress must not be laid on it. The inner cortex is imperfectly preserved ; the outer bark consists chiefly of a thick zone of radially seriated periderm (Fig. 93,f>d), beyond which a narrow band of primary cortex (c) abuts on the surface of the ribs. The leaf- traces are ranged in vertical rows corresponding to the. Fig. ^.Sigillaria (Jikytidohpis type). Segment of stem, in transverse section, includ- ing three ri
. Studies in fossil botany . Paleobotany. SIGILLARIA 227 tions of the primary zone. This latter character may- serve to distinguish a Sigillaria from a Lepidodendron, but too much stress must not be laid on it. The inner cortex is imperfectly preserved ; the outer bark consists chiefly of a thick zone of radially seriated periderm (Fig. 93,f>d), beyond which a narrow band of primary cortex (c) abuts on the surface of the ribs. The leaf- traces are ranged in vertical rows corresponding to the. Fig. ^.Sigillaria (Jikytidohpis type). Segment of stem, in transverse section, includ- ing three ribs, x, crenulated primary wood ; jr2, secondaiy wood ; £d, periderm ; c, outer cortex. X 3. From a photograph by Mr. A. Gepp. ribs of the cortex. The xylem-strands of the leaf-traces start from the depressions of the crenulated primary wood, just as in Sigillaria Menardi or spinulosa, and in Williamson's specimen mentioned above. It is thus evident that each concave segment of the continuous primary wood, in the Rhytidolepis type of stem, corre- sponds to one of the distinct bundles, as shown in the Sub-Sigillarian forms previously described. A more perfect specimen of the stem of a ribbed. 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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