138 MEDULLOSEAE [CH. 



410/i X 280/x, characterised by two curved longitudinal grooves 

 on the surface and regarded by Renault as pollen-grains. The 

 chains of these microspores radiate outwards from the neighbour- 

 hood of the stalk and cover most of the surface of the disc (fig. 

 432, B). Some silicified pieces of similar spore-bearing discs 

 from Grand' Croix named Dolerophyllum fertile^ afford additional 

 information as to these remarkable reproductive organs. The 

 earlier account of this species by Renault is confirmed by Solms- 

 Laubach^ who examined the original sections. The peltate 

 fleshy discs preserved as incomplete specimens consist of lacunar 

 parenchyma 15 — 18 mm. thick traversed at right angles to the 

 surface by numerous locuh (fig. 432, C), circular or oval in trans- 

 verse section, containing large numbers of microspores, s, similar 

 in size and form to those on the carbonised discs of the Mt Pele 

 specimen. Vascular strands occur between and parallel to the 

 spore-chambers. The spores contain 8 — 10 cells (fig. 432, D) 

 and Renault beheves that dehiscence of the exine occurred along 

 the two deep grooves which mark the Hmits of an operculum. 

 He emphasises the peculiar structure of the microspores by 

 speaking of them as prepolHnia : in size and in the presence of 

 internal cells ( ? male prothallus) they resemble the spores found 

 in the pollen -chamber of a seed described by Renault as Aetheo- 

 testa ellipiica^ which he thinks may belong to a member of the 

 Dolerophylleae. It has also been suggested that Codonospermum 

 may be a seed of Dolerophyllum'^ An unconvincing specimen 

 described by Saporta and Marion* as a seed-bearing bract is 

 regarded by them as referable to Dolerophyllum, but the evidence 

 for any connexion is far from satisfactory. 



There is nothing definite to be said with regard to the affinity 

 of Dolerophyllum Goepperti or the microsporophylls represented 

 by D. fertile and the specimens associated with D. Berthieri. 

 Renault considers that both sterile and fertile specimens belong 

 to the same genus, which he assigns to a position between Pterido- 

 phytes and Cycads. As Solms-Laubach says, the evidence sup- 

 pUed by the structure of the veins of D. Goepperti in favour of a 



' Renault (96) A, p. 267, PI. lxxh. ' Solms-Laubach (91) A. p. 126. 



' See Chapter xxxv * Zeiller (06) B. p. 227. 



^ Saporta and Marion (85) fig. 37, p. 76. 



