STIGMARIA 257 



rootlet, attributed to the same plant, remarkable for the 

 perfect preservation of the middle cortex, that Professor 

 Weiss first observed the radial vascular strands, thus 

 confirming Renault's previous statement. 



As mentioned above, the absence of centripetal 

 primary wood from the main axis is not constant in 

 Stigmaria. M. Renault a found this tissue in various 

 cases, and notably in a Stigmaria which he attributed 

 to Sigillaria Brardi. Here the centripetal wood is very 

 distinct, though of no great thickness. It forms more 

 or less separate bundles, so that the structure is not 

 unlike that of the corresponding part of the aerial stem. 



Another species with centripetal wood, the Stigmaria 

 flexuosa of Renault, is regarded by Solms-Laubach 2 as 

 having very probably belonged to the fossil called 

 Stigmariopsis, a form which differs in the shape of 

 the scars from the ordinary Stigmaria, and which is 

 characterised by its well - marked medullary casts, 

 resembling those of a Calamite, though of course with- 

 out the nodal constrictions. Solms-Laubach, from the 

 geological distribution of Stigmariopsis, suggests that 

 it may have constituted the underground organs of the 

 Sub-Sigillariae, while the typical Stigmariae belonged to 

 Eu-Sigillariae as well as to Lepidodendron. This, how- 

 ever, is not yet established, and, in fact, there are few 

 questions in fossil botany more difficult than that of 

 the relation of Stigmaria to its stems. 



Professor F. E. Weiss has quite recently described 

 a very interesting Stigmaria, from the nodules of the 

 Lower Coal-measures, which possesses a perfectly 



1 Flore fossile a'Attitm et oTEpinac, Part ii. p. 226, Plates xxxviii.-xl. 

 2 Ueber Stigmariopsis, Jena, 1894. 



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