XV] 



LEPIDODENDRON 



163 



immediately abut on the primary xylem; at p, p, the section 

 passes through some of the projecting arms of the xylem 

 cylinder; at vi is seen a patch of meristematic zone tissue. 

 This section together with the similar section of Lepidoden- 

 dron vasculare described on a previous page demonstrates that 

 the projecting ridges of the primary xylem form apparently 

 vertical bands : they are not characterised by a lattice-virork 

 arrangement as described by Bertrand and by other authors 

 who have accepted his conclusions. If a reticulum of inter- 

 secting ridges were present on the fiice of the xylem cylinder its 

 existence would be revealed by such a section as that repre- 

 sented in fig. 179, D. 



Fig. 180. Lepidodendron Wiinschianum. From Arran. (i nat. size.) 

 (Sedgwick Museum, Cambridge.) 



6. Lepidodendron Wiinschianum (Williamson). Figs. 180 — 184. 



Reference was made in Volume I. to the occurrence of large 

 stems of a Lepidodendron in volcanic beds of Calciferous sand- 

 stone age in the island of Arrant These were discovered and 

 briefly described by Mr Wiinsch in 1807= and afterwards named 

 by Carruthers Lomatophloyos Wunschianus\ Mr Carruthers 



1 Volume I. p. 89. For other references to these stems, see Seward and Hill 

 (00) p. 918. 



2 Wunsch (67). ^ Carruthers (69=) p. 6. 



