54 Transactions of the Boycd Microscopical Society. 



or atmospheric agency after its discovery, the amorphous cast of the 

 interior with its longer or shorter processes corresponding to the leaf 

 bundles have been supposed to be stems with leaves, and have re- 

 ceived the generic name of Knorria, and the numerous accidental 

 varieties have obtained a large series of specific designations. The 

 longitudinal section (PI. VII., Fig. 4) shows one of these empty 

 canals passing upwards and outwards from the vascular axis. 



From the exterior of the stem spring the bases of the leaves 

 (PI. YIL, Figs. 1 and 2), There is no cuticle to the stem, as its 

 outer surface is entirely made up of the bases of the leaves. The 

 cellular tissue of the leaves is a continuation of the epidermal tissue 

 (PI. YIIL, Figs. 3, 4). The cells in the interior of the leaf are 

 large, and in longitudinal section somewhat oblong. Towards the 

 margin they are much smaller and more compact, forming a firm 

 surface to the leaf. The leaves proper have fallen from the branch 

 figured, and have left a cicatrix which can be detected in those 

 leaves which are cut through the centre, and to some extent it 

 may be seen in the lower leaf in the longitudinal section, PI. VIL, 

 Fig. 4 e. A single bundle passed from the axis into each leaf, 

 and it remained single, for some short distance, through the base 

 of the leaf (PL YIII., Fig. 3), but before reaching the articulating 

 surface to which the true leaf was attached, it divided into two 

 distinct bundles (PI. VIII., Fig. 4). It is important to notice the 

 two appearances that the outer surface of this specimen would 

 exhibit, depending on whether we were examining the surface of the 

 stem or the surface of leaf bases ; in the one case the leaf bundle 

 would be single, in the other double. 



The leaf bases had a direction nearly at right angles to the 

 supporting stem. They were rbomboidal in transverse section, with 

 the lateral angles acute. It is probable that in both Lepidodendron 

 and Sigillaria the leaf bases were persistent, and consequently that 

 the principal character on which Corda separated Lejoidojohloios 

 from Lepidodendron does not hold good. Indeed the specimen 

 which I have now described should be rather placed in Lepidophloios 

 than Lepidodendron, were the two designations retained. 



