. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. MARATTIACEAE 5" fissions in Kaulfussia supports this view (Fig. 281 a-e, lower series). Thus the apparently aberrant genus may be brought into line with the rest. It will be seen later that this spreading of the sori over an enlarged leaf- surface has its parallels among the Leptosporangiate Ferns also. The normal arrangement with one row of sori on either side of the midrib corresponds to what is frequently seen in the fossils which are referred to this affinity: as examples Asterotheca, Scoleco
. The origin of a land flora, a theory based upon the facts of alternation. Plant morphology. MARATTIACEAE 5" fissions in Kaulfussia supports this view (Fig. 281 a-e, lower series). Thus the apparently aberrant genus may be brought into line with the rest. It will be seen later that this spreading of the sori over an enlarged leaf- surface has its parallels among the Leptosporangiate Ferns also. The normal arrangement with one row of sori on either side of the midrib corresponds to what is frequently seen in the fossils which are referred to this affinity: as examples Asterotheca, Scolecopteris, and Ptychocarpus may be quoted (Fig. 282, also Fig. 288 a). In all of these, though the pinnules are small, the arrangement of the sori is on the same plan. But among the Fern-like plants of the Palaeozoic age many other arrange- ments occur which appear to have no near correlative among living Ferns. The examples here chosen from among the fossils are those in which there is at present no reason to doubt the homosporous Fern-character. It is possible that some of them may ultimately be shown to be Seed-. 280. Diagrammatic view of a trunk of a Fern from the Coal, showing above the external cortex with petiolar scars (Cawloptcris), and below the woody cylinder with scars corresponding to the foliar strands, and their sclerotic sheaths \Ptyckaptens). Reduced to \ natural size. (After Zeiller).. 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 Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan and Co. , Ltd.
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