. Fossil plants : for students of botany and geology . Paleobotany. CH. XXXl] PECOPTEEIS PLTJCKENBTI 167 (figs. 225 and 226, vol. ii.). The variation in the form of th& pinnules is shown in fig. 442, A, which represents both the apical portion and parts of pinnae 10 cm. lower on the rachis of a large leaf from the Coal Measures of Radstock. The species is character- istic of the Upper Coal Measures and is recorded also from Permian strata. In 1883 Sterzel adopted for this species the generic name Dicksonites because of the occurrence of shallow circular cups at the end of the lowest latera
. Fossil plants : for students of botany and geology . Paleobotany. CH. XXXl] PECOPTEEIS PLTJCKENBTI 167 (figs. 225 and 226, vol. ii.). The variation in the form of th& pinnules is shown in fig. 442, A, which represents both the apical portion and parts of pinnae 10 cm. lower on the rachis of a large leaf from the Coal Measures of Radstock. The species is character- istic of the Upper Coal Measures and is recorded also from Permian strata. In 1883 Sterzel adopted for this species the generic name Dicksonites because of the occurrence of shallow circular cups at the end of the lowest lateral vein on some of the pinnules which he believed to be sori of the Cyatheaceous type. The cups. Fig. 442. Pecopteris Pluckeneii. A, apex and lower pinnae (Kidston Coll., 234); B, pinnule with supposed sorus (after Sterzel); C, pinnule with seeds (after Zeiller). have an involute margin and occasionally a small scar in the centre (fig. 442, B). Sturi dechned to accept Sterzel's evidence as satisfactory and suggested a fungal origin for the sorus-Uke impressions, a view, as Sterzel objected, that is rendered improbable by the constant position of the single cups on several pinnules. The nature of Sterzel's 'sori' has not been demonstrated: it is. suggested by Grand'Eury^ that they mark the position of micro- Stur (85) B. p. 293. = Grand'Eury (OS).. 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
