228 STUDIES IN FOSSIL BOTANY 



Sigillaria (probably S. elongatd), from the Hardinghen 

 coal-field, in the Pas de Calais, has been described by 

 Professor C. E. Bertrand {Annals of Botany, December 

 1899). His more complete observations agree essenti- 

 ally with the short account just given of an English 

 specimen. Professor Bertrand points out that the 

 ribbed Sigillaria is in certain respects intermediate in 

 structure between the Sub-Sigillariae and the Lepido- 

 dendra with secondary growth. 



More recently Mr. Kidston has given a full account 

 of the structure of a petrified specimen of Sigillaria 

 elegans from the Lower Coal-measures of Yorkshire. 1 

 This is a Favularian species ; the characteristic leaf-scars 

 are shown quite plainly on the surface of the specimen. 

 The structure of the stele is essentially the same as in 

 the form already described, and here also the leaf-traces 

 invariably start from the base of the furrows of the 

 crenulated primary wood. The medullary rays are 

 one cell thick, and of varying height ; their cells, as in 

 Lepidodendron, sometimes show scalariform markings 

 The leaf-trace has a distinctly mesarch structure, and 

 is without any secondary xylem. The structure of the 

 bodies known as " cone scars " shows them to be the 

 bases of small lateral branches, which may well have 

 borne the fructifications (see p. 214). 



Quite lately the structure of certain species of the 

 Rhytidolepis group has been investigated by Kidston 

 and by Arber and Thomas 2 in material from the 



1 Kidston, " On the Internal Structure of Sigillaria elegans, " Trans. 

 Roy. Soc. of Edinburgh, vol. xli. Part iii. 1905. 



2 Kidston, ' ' Prelim. Note on Internal Structure of Sigitlaria mamillaris 

 and 5. scutellata" Proc. Roy. Soc. Edinburgh, vol. xxvii. Part iii. 1907; 

 Arber and Thomas, " On the Structure of Sigillaria scutellata, etc.," Proc. 

 Roy. Soc. London, 1907 (abstract). 



