54 DESCRIPTION OF FOSSIL TREES DISCOVERED 



verse section is represented by Fig. 1. Plate XIII., (much altered), the cel- 

 lular or parenchymatous tissue is, at the surface of the stem, surrounded by a 

 very thin layer of tissue, which assumes a remarkable degree of regularity, 

 and of which some remaining portions are represented by the black curved 

 line at b, b, b. It is seen magnified in Fig. % d, d, of Plate XIII., which is a 

 portion of a transverse section, including the pith, b, b, and the other parts 

 to the surface. Fig. 3. of the same plate, shews it more highly magnified. 

 The tissue of the superficial layer has a striking resemblance to that of the 

 woody tissue of the Coniferap, the cellules being disposed in regular series, 

 and of a form approaching the hexagonal, but without indications of me- 

 dullary rays. In this more regular portion of the cellular tissue, circular 

 vacuities are observed, resembling the lacunae of the Coniferse, or the aper- 

 tures of vasa propria. 



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 this opinion. A transverse section of Lyco- 

 podium clavatum is represented by Fig. 8. Plate XII. ; but as I have had 

 no opportunity of examining the structure of any large recent species, and as 

 I have seen no figures, it does not become me to institute any comparison. 

 Whatever light may be thrown on the nature of the Lepidodendra by the 

 anatomy of the present species, I must leave to persons 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 

 above described evidently belongs to the vascular cryptogamic class, and 

 that in its structure there is nothing to invalidate the opinion derived from 

 the external configuration of the Lepidodendra, that they are Lycopo- 

 diacea;. 



The zeal and activity of the gentleman from whom the first specimen 

 of this fossil was obtained, have induced me to name the species Lepido- 

 dendron Harcourtii. 



