238 LYCOPODIALES [CH. 



Lepidodendron, the Stigmariopsis form having the corresponding 

 relation to the Leiodermarian-Clathrarian species. 



The opinion expressed by Williamson^ in 1892 that Grand'- 

 Eury's hypothesis " appears to be identical with the vague and 

 speculative guesses that were prevalent among us in the early 

 years of the present [nineteenth] century" illustrates the 

 strength of conviction based on English specimens as to the 

 root-nature of Stigmaria. 



There is undoubtedly considerable confusion, which can be 

 cleared up only by further research, as to the precise relation 

 between Stigmaria and Stigmariopsis on the one hand and the 

 different types of Sigillariae on the other. The main contention, 

 and this is the most important point, of Renault, Grand'Eury 

 and Solms-Laubach as to the manner of formation of the aerial 

 shoots from rhizomes and the subsequent production of forked 

 roots and their ultimate separation from the parent rhizome 

 is, as I believe, correct. Williamson held that Stigmaria must 

 be regarded as a true root; he found no evidence to support 

 the view that the large rooted stem discovered by Hawshaw, 

 Binney, and others had been originally produced from aquatic 

 rhizomes. It must, however, be remembered that Grand'Eury's 

 opinion is based on evidence afforded by the exceptionally well 

 displayed Sigillarian forests of St Etienne, on a scale such as 

 English strata have not as yet afforded. Moreover, the absence 

 of any parent-rhizome in association with the rooted stumps 

 described by Williamson and by others is not a serious argu- 

 ment against their rhizome origin. 



The specimen represented in fig. 209, which was examined 

 m situ by Solms-Laubach and Grand'Eury, shows a Sigillarian 

 stem in the Syringodendron condition bearing rows of paired 

 parichnos scars ; from the base forked and rapidly tapering 

 arms radiate through the surrounding rock and, as shown by 

 other specimens, these bear numerous appendages like those of 

 the English Stigmarias. The surface-features of the arms are 

 those of Stigmariopsis and the centre of each, as seen on the 

 broken face, is occupied by a pith-cast characterised by parallel 

 longitudinal ridges resembling those on the medullary casts of 



1 Williamson (92). 



