. Fossil plants : for students of botany and geology . Paleobotany. 130 MEDULLOSEAE [CH. in which they agree closely with the spores of Dolerofhyllum fertile described by Renault^, In both cases the spores tend to be arranged in long groups and they are practically identical in form and in the nature of the exine; those of Dolerophyllum are 280/x long while those of W. fertilis reach a length of 220yn. In some of_ the Whittleseya spores the exine has split as in the specimen shown in fig. 429, but in others there are two curved lines along which dehiscence has begun, a character in which the s
. Fossil plants : for students of botany and geology . Paleobotany. 130 MEDULLOSEAE [CH. in which they agree closely with the spores of Dolerofhyllum fertile described by Renault^, In both cases the spores tend to be arranged in long groups and they are practically identical in form and in the nature of the exine; those of Dolerophyllum are 280/x long while those of W. fertilis reach a length of 220yn. In some of_ the Whittleseya spores the exine has split as in the specimen shown in fig. 429, but in others there are two curved lines along which dehiscence has begun, a character in which the spores appear to be identical with those of Dolerophyllum. A B Fig. 429. Microspores of Whittleseya elegans. A, a group of spores; B, a spore. (Preparations made from an American specimen, No. 2314, in Dr Kidston's Collection.) described by Renault who speaks of dehiscence by means of an operculum. There is, I venture to think, Uttle doubt as to the very close affinity of the two types. The systematic position of Dolerophyllum is not certainly established; if the generic identity of the leaves described as D. Berthieri Ren. and the petrified specimens named D. fertile is assumed, it is a legitimate inference that the genus is founded on fertile pinnules of a Pterido- sperm with foliage of the Neuropteris or Cyclopteris form. It would seem probable that both Whittleseya and Dolerophyllum 1 Renault (93) A. PI. Lxxii; (96) A. p. 268. See page 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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