118 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



Will.'), and Sphenophyllum pluri/oliatiim, Will, and Scott, the 

 primary bundle is triarch, but in some French specimens of 

 Sphenophyllum, one of which is figured by Williamson and Scott, 

 the primary bundle is hexarch." 



In Sphenophyllum plurifoliatwm the secondary tracheides have 

 pitted walls, and in the angles formed between the corners of the 

 tracheides, parenchymatous cells occur. In the fascicular wood 

 medullary rays exist from the first; in the interfascicular wood 

 they are absent at first, or only occur irregularly. 



In Sphenophylluvi insigne there is a canal at each angle of the 

 primary triarch xylem, the tracheides are scalariform, and 

 medullary rays are a constant character in both fascicular and 

 interfascicular xylem. 



Sphenophyllum plurifoliatum occurs in the Coal Measures, and 

 Sphenophyllum insigne in the Calciferous Sandstone series. 



The root of Sphenophyllwn has been described and figured by 

 Benault in several of his writings.^ It consists of a small diarch 

 primary bundle surrounded by a secondary xylem zone formed of 

 pitted tracheides. The specimen does not, however, appear to 

 have been very well preserved.'' ^ 



1 Williamson, Asterophyllites, Mem. V., p. 49. Phil. Trans., 1874. 

 Williamson, Atttrophyllites insignis, "General Morphological and Histo- 

 logical Index," &c., Part i. ; Mem. and Proc. Manchester Lit. and Phil. Soc, 

 1S91, p. 13. Williamson, AsterophylUtes sphtnophylloidfs, ibid., Mem. and 

 Proc. Manchfsfer Lit. and Phil. Soc, 1891, p. 12. Williamson and Scott, 

 " Further Observations on the Organization of the Fossil Plants of the 

 Coal Measures," Phil. Trans., Vol. CLXXXV., p. 920, 1895. 



- Williamson and Scott, "Further Observations on the Organization of 

 the Fossil Plants of the Coal Measures," I., Phil. Trans., Vol. CLXXXV., 

 PI. LXXVL, fig. 24. 1895. 



^ Renault, Eecherches sur la struct, et les affln. botan. d. v6git. silieifids, 

 187S, p. 189, PI. XXIX., figs. 5, 6; Nouv. rech. sur la struct, d. Spheno- 

 phyllum, p. 23, PI. VIII., figs. 5, 6, 1876; Cours d. botan. foss.. Vol. IV., 

 1885, p. 31, PI. B., fig. 2; Bassin houiller et permien d'Atdun et d'Epinac: 

 Florefoss., Part 2, p. 155, PI. LXIV., fig. 11. 1896. 



* See Seward, Fossil Plants, Vol. I., p. 399. 1898. 



^ For a detailed description of the structure of the stem of Sphenophyllum 

 see further : — 



Renault, Rtcherches sur la structure et les affinitds botanique des vdgetaux 

 silieifids reeueilles aux environs d'Autun et de St. Etienne, p. 158, plates. 

 Autun, 1878 ; Cours d. botanique fossile, Vol. II., 1882, p. 81 ; ibid., Vol. 



