XVl] SIGILLARIA 219 



series, usually one cell broad, of parenchymatous cells with 

 occasional short rays one or more cells in depth. 



The slightly greater breadth of the rays between each 

 primary xylem strand tends to divide the secondary wood 

 into bundles corresponding in breadth to the primary groups. 

 The outer cortex closely resembles that of Lepidodendron ; 

 it consists internally of radial series of secondary, elongated 

 and rather stout, elements abutting on the parenchymatous 

 tissue of the leaf-cushions. 



The next contribution to our knowledge of the anatomy of 

 Sigillaria was made by Renault and Grand'Eury^ who described 

 the structure of Sigillaria spinulosa Germar^, a species now 

 recognised as the Leiodermarian condition of S. Brardi, and 

 probably, therefore, not specially distinct from the specimen 

 described by Brongniart in 1839 as 8. elegans. In Brongniart's 

 fossil the leaf-cushions are in contact (Clathrarian form of S. 

 Brardi: fig. 203, upper part) whereas in the specimen now 

 under consideration the leaf-scars are further apart (Leioder- 

 marian form of S. Brardi, fig. 203, lower part, and fig. 196, C). 

 It may be, as Scott suggests, that these two specimens are not 

 specifically identical but closely allied, an opinion based on 

 certain anatomical differences^; we may, however, include both 

 under the comprehensive name 8. Brardi. 



The primary xylem (fig. 200, B, x), is in some regions 

 separated into distinct strands, in others it forms a continuous 

 band equal in length to several of the separate groups. This 

 type of stele, in which the primary xylem consists in part of 

 separate strands and in part of a continuous cylinder, forms a 

 transition between that represented in fig. 200, A, and the steles 

 of Sigillaria elegans (fig. 202, A) and most species of Lepido- 

 dendron. The tendency of the primary xylem strands to become 

 united laterally, forming broader bands, was first described by 

 Solms-Laubach^ in a French specimen of Sigillaria spimdosa in 

 the Williamson collection. The leaf-traces arise from the middle 

 of the concave outer face of the primary xylem groups. The inner 

 cortex is composed of small parenchymatous cells as in Lepido- 



1 Benault and Grand'Eury (76) ; Renault (96) A. = Germar (44) A. 

 3 Scott (08) p. 219. * Solms-Laubach (91) A. p. 253. 



