CARBONIFEROUS LYCOPODS AND SPHENOPHYLLS. 113 



From the study of Stigmaria {Stigviariopsis ?) Brardi, Renault, 

 it would appear that the coaly layer which surrounded the 

 calamite-like cast of the specimen of Stigmariopsis described by 

 Solms-Laubach represented both the primary and the secondary 

 xylem, and that the elongated depressions seen on its outer 

 surface were the openings of the primary medullary rays. 



If I am correct in referring these specimens to Stigmariopsis, 

 it differs from Stigmaria in possessing a centripetal zone of 

 xylem, succeeded by a centrifugal secondary zone. In Stigmaria 

 the primary centripetal zone is absent, and the cast of the pith 

 cavity shows on its outer surface the impression of the netted 

 cylinder which has been so well figured by Williamson.^ 



Solms-Laubach has thrown out the suggestion that Stigmaria 

 Jicoides is the deep-water rhizome of tlie Sigillarice generally, and 

 that Stigmariopsis is peculiar to the Clathraria-Leiodermaria 

 group. If this be so, it would explain the comparative rarity of 

 Stigmariopsis in Britain, where the Clathraria-Leiodermaria groMjy 

 of Sigillaria is not common. But, strangely enough, the 

 example which Solms-Laubach investigated, and which he gives 

 on Plate I., fig. 1, in illustration of his paper, " Uher Stig- 

 mariopsis," appears to show a Syringodendron condition of a 

 member of the Rhytidolepis, or ribbed section of Sigillaria, and 

 to the same group clearly belong his figures 3 and 5 of Plate III. 



I only know of two "species" of Stigviariopsis from British 

 carboniferous rocks. One is similar in all characters to that 

 described by Goldenberg under the name of Stigmaria rimosa," 

 from the Hirschbach mine, near Dutweiler. 



I have seen specimens of Stigmariopsis rimosa, Goldenberg sp., 

 from the Lower and Middle Coal Measures, and also from the 

 Carboniferous Limestone Series of Scotland, but among these 

 there must be the rhizomes of different species, as we know of no 

 Lycopod in Britain which passes from the Lower to the Upper 

 Carboniferous. 



The same difficulty occurs with Stigmaria, which is known to 

 be the rhizome, not only of many species, but of, at least, two 

 genera — Lepidodendron and Sigillaria — as hitherto no characters 



^Monog. Stigmaria, PI. XIV., fig. 69. 



"Goldenberg, Flora Sarcepontana foss., Heft. III., p. \5, PI. XII., figs. 

 3-tJ, named on Plate Stigmaria uhbreviatu. 



