48 



FOSSIL PLANTS. 



destroyed in the specimen), and the vascular cylinder of seven barred vessels on each side. 

 Those next the pith being considerably larger than those on the outside. 



Fig. 10 represents a longitudinal section of a portion of the wall of the sporangium, 

 composed of a single line of transversely elongated cells, and a group of microspores, 

 composed of crude paraffine, and dividing into three, four, and five sporules, but far more 

 frequently into three ; magnified fifty diameters. 



This specimen in all its parts resembles Dr. R. Brown's Cone ; and the only additional 

 information that it affords is the structure of the central axis wanting in his specimen. 

 The structure of the central axis in the Oldham specimen in all its parts, except the 

 medulla of cellular tissue, is so closely identical with that of the stem of Lepidodendron 

 Harcourtii (see Specimen No. 18, fig. 6, next described), that there can be little doubt as 

 to its having been the fructification of that plant ; and most probably Dr. Brown's 

 specimen belonged to it also, as it exactly resembles my specimen, except that the central 

 axis has been destroyed so far as structure is concerned. Now M. Brongniart is of 

 opinion that Dr. Brown's Triplosporites is identical with his specimen. If this be so, 

 the last-named genus has to be merged into Lepidostrohus} if not to Lepidodendron 

 Harcourtii. 



Specimen No. 18, Lepidodendron Harcourtii (Plate VII, fig. 6). 



Fig. 6 is the transverse section of the inner portion of a stem of Lepidodendron 

 Harcourtii, magnified ten diameters, showing the central axis or pith composed of fine 

 cellular tissue, surrounded by a zone of fine vascular tubes (of a hexagonal form, and 

 having their sides barred with transverse striae) and a sinuous boundary-line, of a dark 

 colour, from which spring the vascular bundles that communicate with the leaves. The 

 outer portion of the specimen clearly shows the band of lax cellular tissue, traversed by 

 vascular bundles, and the outer radiating zone so usually found in stems of Lepidodendron 

 exhibiting structure. 



This specimen was presented to me by Mr. J. S. Dawes, F.G.S., and was found by 

 him in the Dudley Coal-field. It is described and figured for the purpose of showing 

 the identity of the structm-e of the stem of Lepidodendron Harcourtii with that of the 

 axis of the Cone above described. If similarity of structure is of any value in proving 

 the connection of organs of fructification with a stem, the Oldham Cone must be held to 

 belong to Lepidodendron Harcourtii. 



' As Dr. Browa himself and Mr. Carruthers also have sliowu ; see ' Geol. Mag.,' vol. ii, p. 437. 



