XVII] STIGMARIOPSIS 235 



from the base of erect stems; the horizontal rhizomes of all 

 Sigillarian stems he refers to Stigmaria. The pith-casts of 

 Sigillariopsis may be recognised by their long vertical ridges 

 and grooves, a feature readily understood by reference to the 

 stem structure. The Stigmariopsis rhizomes though rare in 

 England have been recognised by Dr Kidston^ in the Middle 

 Coal-Measures of Yorkshire; he has figured a pith-cast very 

 like that illustrated in Solms'-Laubach's Memoir as Stigmariopsis 

 anglica. 



The surface-features of a Stigmariopsis pith-cast are clearly 

 shown on a specimen from St l^tienne in the Williamson 

 collection^. 



The most complete account of Grand'Eury's views in regard 

 to the anchoring and absorbing organs of Sigillaria is given in 

 his monograph on the Coal-field of Gard^ St Etienne, and these 

 are clearly stated also by Solms-Laubach' who confirms the 

 conclusions of the French author as to the manner of develop- 

 ment of the aerial shoots. Grand'Eury believes that both 

 Stigm,aria and Stigmariopsis are rhizomes and not true roots. 

 The surface-features of Stigmaria have already been described. 

 This type Grand'Eury speaks of as characterised by the uniform 

 diameter and considerable horizontal elongation of the bifur- 

 cated axes ; he thinks they grew both as floating rhizomes and 

 on the ground : they may frequently be traced for a consider- 

 able distance without showing any signs of connexion with 

 aerial shoots, but occasionally they have been seen in organic 

 union with Sigillarian stems. He believes that these rhizomes 

 were produced as the result of germination under water of the 

 spores of Sigillaria or Lepidodendron and developed as long and 

 branched aquatic rhizomes capable of independent existence. 

 Under certain conditions, as he thinks in shallower water, the 

 rhizomes produced bulb-like outgrowths which grew into erect 

 stems having the surface-features of Sigillaria. This method 

 of origin is practically the same as that described by Goeppert 

 in 1865. The vascular meduUated cylinder of these erect 



1 Kidston (02) PI. li. fig. 4. 2 British Museum, No. 870 F. 



3 Grand'Eury (90) A. * Solms-Laubach (94). 



