4 Scientific Proceedings, Royal Dublin Society. 



pinnule consists of a short racliis bearing six or seven lateral, alternating 

 arms, eacli ending in a disk-like expansion, the underside of which bears 

 an epaulette-like ' fringe ' of pendent finger-like bilocular pollen-sacs or 

 bisporangiate synangia. Dehiscence of the pollen-sac was longitudinal, and 

 the pollen-grains or microspores were tetrahedrally arranged. 



There is nothing in its structure to prevent the male pinnule from 

 being described as a naked, branched rachis bearing groups of sori of 

 synangia. Tlie foliar nature of tlie structure is obvious. 



Female. — Lyginodendron is characterized by tlie presence on its stem and 

 all parts of its leaf of the bramble-like prickles or hooked emergences 

 already mentioned, and of stalked glands. F. W. Oliver was struck by the 

 similarity of these glands to those observable on a seed found in the same 

 deposits (Coal Measures), and known as Lagenostoma Lomaxi, Willm., MS. 

 With D. H. Scott he published in 1903 a detailed account of the internal 

 structure of this seed, which presents, it was found, characters indicating 

 close afEnity with the seed of a Cycad. Notliing but evidence of direct 

 continuity between this seed and the vegetative organs of Lyginodendron 

 was lacking; and Oliver and Scott accordingly felt justified in concluding 

 that Lagenostoma Lomaxi was the seed' of Lyginodendron, and that it had 

 become detached before it was ripe, as occurs in some Oycads and in Gnetum 

 Qnemon"^ to-day. Another feature of Lagenostoma Lomaxi is the presence of 

 a cupule-like envelope, which has been compared to the husk of a hazel-nut. 

 This envelope consists of some six lobes united below and free above. Each 

 lobe shows on its outer surface the glands already mentioned. Naturally a 

 search was made to discover anything more indicative if possible of the con- 

 nexion between this isolated seed and Lyginodendron. Now, in 1875 Stur 

 published the first part of his great work on the Culm Flora, and there 

 figured certain bodies as " indusia spuria," suggesting that they were the five- 

 to sis-rayed indusial lobes of some fern. In 1877 he published tlie second 

 part of his work, and in it was able to assign liis " indusia spuria " 

 definitely to a fossil fern, Calymmatotheca. In 1883 he went still further, and 

 described several species of Calymmatotheca, showing a gradual diminution in 

 size of the indusial lobes. One of these — 0. Stangeri — shows on the indusial 

 lobes emergences which suggested to Scott and Oliver that C. Stangeri 

 represented a fertile frond of Lyginodendron oldhamium from which the seeds 

 had been shed. A difficulty militating against the acceptance of the idea of 

 the complete identity of the two is the fact that the L. Lomaxi seed carried 

 its cupular lobes on it, and that in 0. Stangeri the lobes remain on the parent 



' It was this discovery that caused these authors to found the group Pteridospermea, to include 

 seed-bearing Cycadofilices. ^ Lotsy : Vortrage ii. hot. Stammesgeschichte, Bd. ii., 1909, p. 716. 



