138 STUDIES IN FOSSIL BOTANY 



56, A). They have a complex spiral arrangement, 

 related to that of the leaves to which they ran. 1 



The structure of the individual leaf-trace bundles in 

 L. Harcourtii has been described as characteristic of the 

 species ; its peculiarity consists in the. presence of a 

 conspicuous strand of dark-coloured, apparently fibrous 

 cells, on the outside of the bundle (see Fig. 56, B, l.tf). 

 Other Lepidodendreae, however, show the same structure, 

 as Prof. Seward found in the case of Lepidophloios 

 fuliginosus, and Mr. Watson in his new species, Lepi- 

 dodendron Hickii. That the elements in question were 

 really of the nature of hard bast is very improbable. 

 Prof. Bertrand regards them as organs of secretion, 

 comparable to laticiferous cells, and Prof. Seward's 

 observations led him to a similar conclusion, 2 which 

 may be provisionally accepted. 



The vascular bundles appea'r, judging from the best- 

 preserved specimens, to have been of the collateral type, 

 the phloem lying between the xylem and the strand of 

 secretory elements, and perhaps including the latter. 

 The spiral tracheae are placed near the middle of the 

 xylem, a position which they often occupy in the foliar 

 bundles of Lycopods. Outside the phloem of each 

 bundle, where it traverses the outer cortex, is a large 

 strand of delicate parenchyma, seldom perfectly pre- 

 served, which was continuous with the parichnos of the 

 leaf-base. 



1 For a detailed account of the anatomy of L. Harcoartii, see Bertrand' 

 Remarques sur le Lepidodendron Harcourtii de IVithaw, ~Li\\e, 1891. For 

 L. Hickii see Watson, " On a Confusion of two Species under Lepidodendron 

 Harcourtii" Mem. and Proc. Manchester Lit. and Phil. Soc. vol. li. 

 Part iii. 1907. 



2 A. C. Seward, " Notes on the Binney Collection of Coal-measure 

 Plants," i. Lepidophloios, Proc. Cambridge Phil. Soc. vol. x. 1899. 



