. Fossil plants : for students of botany and geology . Paleobotany. XVI] SIGILLARIA 205 in France, the parichnos scars reach a length of 3 cm. As seen in the fragment of a ribbed Sigillaria represented in fig. 198, the large parichnos areas exhibit a distinct surface pitting in contrast to tlje fine longitudinal striation of the rib; the difference in surface-appearance is due to the nature of the tissue, which in the parichnos consists of fairly large parenchy- matous elements with groups of secretory cells^ and in the exposed cortex of elongated elements. The vertical line in the middle of f
. Fossil plants : for students of botany and geology . Paleobotany. XVI] SIGILLARIA 205 in France, the parichnos scars reach a length of 3 cm. As seen in the fragment of a ribbed Sigillaria represented in fig. 198, the large parichnos areas exhibit a distinct surface pitting in contrast to tlje fine longitudinal striation of the rib; the difference in surface-appearance is due to the nature of the tissue, which in the parichnos consists of fairly large parenchy- matous elements with groups of secretory cells^ and in the exposed cortex of elongated elements. The vertical line in the middle of fig. 198, which occurs in the middle of the rib, has probably been formed by splitting of the Fig. 198. SiSfiZ^arm with large parichnos areas. (^ nat. size.) Grand'Eury's description of fossil forests of Sigillariae in the rocks of the St :6tienne= district affords a striking picture of these arborescent Pteridophytes; he speaks of the stems of some of the trees as swollen like a bottle at the base, characterised by the Syringodendron features and terminating below in short repeatedly forked roots of the type known as Stigmari- opsis. Other specimens of Sigillaria stumps show a marked decrease in girth towards the base; this tapered form is regarded by Grand'Eury as the result of the development of aerial columnar stems from underground rhizomes. The nature of the root-like organs of Sigillaria is dealt with in the sequel: a brief reference may, however, be made 1 Coward (07) ; Renault (9C) A. 2 Grand'Eury (90) A. PI. 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 Seward, A. C. (Albert Charles), 1863-1941. Cambridge : University Press
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
