Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne 1838 Vol.2.djvu/262

 bears a considerable resemblance to one of Lycopodium clavatum, Fig. 9, Pl. V. Fig. 6, Pl. V. represents an oblique section in which the meshes are more entire than usual.

From certain indications presented by some of the transverse sections of the stem, it would seem that bundles of vessels exist round the axis or pith, as seen in Fig. 4, a, a, and Fig 2, e, Pl. VI.

The above is the ordinary structure of the stems as usually observed in specimens; but in a stem of somewhat greater diameter, of which a transverse section is represented by Fig. 1, Pl. VI. (much altered), the cellular 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, b b. It is seen magnified in Fig 2, d d, which is a portion of a transverse section including the pith, b b., and the other parts to the surface. Fig. 3 shews it more highly magnified. The tissue of this superficial layer has a remarkable resemblance to that of the coniferae, the cellules being arranged in parallel series, and of a form approaching to the hexagonal, but without indications of medullary rays. In this more regular portion of the cellular tissue circular vacuities are observed, which are probably 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 the opinion A transverse section of Lycopodium clavatum is represented by Fig. 8, Pl. V., 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. Whatever light may be thrown on the nature of the Lepidodendron 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 opinion derived from the external configuration of the Lepidodendra, that they are Lycopodiacias.