11 2 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



Stigmaria Brardi, Renault, from Dracy-Saint-Loup is referable 

 to Stigmariopsis} 



In Stigmaria Brardi there is the very fortunate circumstance 

 of the preservation of the outer surface of the bark, which 

 possesses all the character of Stigmariopsis. The rootlet scars 

 are arranged in quincuncial oi'der, and between them the bark 

 shows the elongated mesh-like reticulation. The axis consists of 

 a medullary cavity from which the tissue has disappeared. This 

 is surrounded by a circle of centripetally developed bundles 

 composed of irregularly placed vessels, which eventually unite 

 laterally, their apices remaining free, and projecting into the pith 

 cavity, where they form a prominent corona. The core of such 

 a cavity, would form a cast similar to those described by Solms- 

 Laubach in the stem examined by him at St. Etienne. The 

 primary zone of xylem is surrounded by a secondary exogenously 

 developed zone whose elements are radially arranged. This 

 secondary zone seen in tangential section shows numerous large, 

 primary medullary ray openings, similar to those occurring in 

 Stigmaria, and through which the rootlet bundles pass from the 

 primaiy zone of xylem, and thus go outwards to the rootlets. 



The rootlet bundles show a group of primary vessels, arranged 

 without order, to whose outer surface a fan-shaped secondary 

 xylem of radially arranged elements is added. 



The subepidermal layer shown at PI. XXXVIII., fig. 9, is 

 apparently similar to the structure given on PL XXXIX,, fig. 12 

 (though only named Stigmaria), of which tangential sections are 

 given enlarged on PI. XXXIX., figs. 13 and 14. These show a 

 number of longitudinal flexuous bands of fusiform cells with 

 reticulated walls, which uniting among themselves form a net-like 

 structure, the meshes of which are filled with smooth walled 

 parenchyma. It is this dictyoxyloid structure which impresses 

 upon the outer surface of the rhizome the net-like reticulation 

 which appears to be one of the distinguishing characters of 

 Stigmariopsis. 



1 Renault, Bassin houilltr et permien d'AuUm el d'Epinac, Fasc. IV. 

 Flore /ossile, Deux part, p. 231. Atlas, PL XXXVIII., figs. 5-9; PL 

 XXXIX., figs. 1-10, 1893. Also probably »S'i!i^man'a, ibid., PL XXXIX., 

 figs. 12-14. 



