Mr Withani on the Lepidodendron Harcourtii. 369 



the transverse section of the stem it presents the appearance of 

 pretty regular meshes, assuming niore or less of a polygonal 

 form, as seen in Fig. 4, PI. IV. The cellular tissue is more 

 condensed towards the surface of the stem, as is represented at 

 c of the same figure, which also shews, at a, the appearance of 

 one of the processes, in which the cellular substance and ves- 

 sels have been thrust aside, and the cavity filled by calcareous 

 spar. 



The meshes of the general mass of cellular tissue are some- 

 what elongated in the longitudinal direction of the stem, but 

 present the same general appearance. 



The Lepidodendra are generally supposed to be Lycopodia, 

 or plants allied to them, and there is nothing in the structure of 

 the present species that might tend to invalidate the opinion. A 

 transverse section of Lycopodium clavatum is represented by 

 Fig. 5. PI. IV., but as I have had no opportunity of examining 

 the structure of any large recent species, and as no figures of 

 such exist, it does not become me to institute any comparison. 

 AVhatever light may be thrown on the nature of the Lepidoden- 

 dron by the anatomy of the present species, I must leave to 

 others better qualified than myself to point out ; but, I trust, 

 the figures which I have given will be useful for comparison, 

 should other species occur, in which the structure may be found 

 to have remained. This much is certain, that the plant here 

 described evidently belongs to the vascular cryptogamic class, 

 and that in its structure there is nothing to invalidate the opi- 

 nion derived from the external configuration of the Lepidoden- 

 dra, that they are Lycopodiacia?. 



VOL. XIV. NO. XXVI II. APRIL 1833. A a 



