. Fossil plants : for students of botany and geology . Paleobotany. xxix] SPHAEROSTOMA 79 associated with Heterangium Grievii almost amounts to demon- stration of continuity between vegetative organs and seeds. Sphaerostoma ovale (Williamson). In 1877 Williamson described some detached petrified seeds irom the Lower Carboniferous rocks of Fifeshire, Scotland, as Conostoma ovale and C. intermedium. Dr Benson's investigation^ of these two forms leads her to confirm Williamson's doubts as to the validity of a specific separation and she assigns the single. Tig. 414. Sphaerostoma ovale. A. Longitu
. Fossil plants : for students of botany and geology . Paleobotany. xxix] SPHAEROSTOMA 79 associated with Heterangium Grievii almost amounts to demon- stration of continuity between vegetative organs and seeds. Sphaerostoma ovale (Williamson). In 1877 Williamson described some detached petrified seeds irom the Lower Carboniferous rocks of Fifeshire, Scotland, as Conostoma ovale and C. intermedium. Dr Benson's investigation^ of these two forms leads her to confirm Williamson's doubts as to the validity of a specific separation and she assigns the single. Tig. 414. Sphaerostoma ovale. A. Longitudinal section showing the cupule, c, integument, e, f, with vascular bundle, v, the upper part of the nucellus, n, and megaspore, m; a, arohegonia. B. Transverse section through the roof of the pollen-chamber, pc, and the summit of the nuceUus, n. (After Benson.) "type to the new genus Sfhaerostoma. The seeds are always associated with the vegetative organs of Heterangium Grievii. In 1909 Oliver^ expressed the opinion that the Burntisland species of Conostoma (= Sphaerostoma,) is probably the seed of Heterangium. The seed consists of a central body representing the nucellus, an inner integument, and an enveloping cupule or outer integument: most specimens have lost the cupule and in this condition they are 3-5 mm. long with a maximum breadth of 2-2 mm. In the ^ Benson (14). 2 OUver (09) p. 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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