. Piante fossili : per gli studenti di botanica e geologia . Paleobotanica. 288 PITYEAE [CH. da p. antiqua nel più ampio e la forma più breve e una maggiore ampiezza dei raggi midollare (fig. 488, A, B), anche nel più grande e tracheids in meno affollata di disposizione delle buche bordate in cui la forma circolare sostituisce talvolta l'esagonale. Fig. 488. Pitys primaeva. A sezione trasversale dello xilema secondario; B, sezione tangenziale del xilema secondario. (Dalle sezioni del tipo- campione nella Edinburgh University Dipartimento di Botanica.). La struttura del midollo non è noto, ma Scot
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. Fossil plants : for students of botany and geology . Paleobotany. 288 PITYEAE [CH. from p. antiqua in the broader and shorter form and greater breadth of the medullary rays (fig. 488, A, B), also in the larger tracheids and in the less crowded arrangement of the bordered pits in which the circular form sometimes replaces the hexagonal. Fig. 488. Pitys primaeva. A, transverse section of the secondary xylem; B, tangential section of the secondary xylem. (From sections of the type- specimen in the Edinburgh University Botanical Department.) type. The structure of the pith is not known, but Scott was able to recognise in the partially preserved pith of a branch indica- tions of primary-xylem groups and other features pointing to a close resemblance to P. antiqua^. A piece of stem originally 1 Since this chapter was written Prof. W. T. Gordon has kindly supplied the following summary of his unpublished work on the genus Pitys. 'The re-examination of Pitys primaeva and P. antiqua in the light of the structure exhibited by numerous specimens of a new species recently discovered in Haddingtonshire has shown that all three types are similar as regards the structure of the primary wood. In each case the primary cylinder is comparable with that in Archaeopitys Eastmanii [see p. 290], i.e., there are medullary as well as oiroum-meduUary xylem-strands. In certain specimens of the new species, Pitys Dayii, the bark and leaves are preserved and thus the details of leaf-trace emission from the stem have been determined. The leaves are short and stout and taper gradually to a point, quite distinct from the long, thin, spatulate Cordai- tean foliage. The internal structure of the leaf renders it easily distinguishable from the Cordaites type while it tends to accentuate the possible relationship of Pitys with the Lyginodendreae.'. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of
