QQ TRANSACTIONS, NATURAL HISTORY SOCIETY OP GLASGOW. 



The leaf appears to consist of two parts, the blade and the 

 basal portion. The basal portion, which is separated from the 

 blade by a slight constriction, is probably the part which was 

 attached to the cushion, and whose removal from the stem exposes 

 the leaf -scar. 



The long grass-like leaves of such species as Lepidodendron 

 longifolium, Brongt., and Lepidodendron obovatum, Sternb., form, 

 in part, the Cyperites of Lindley and Hutton. l 



VII. Stigmaria, Brongniart, 1822. 

 1822. Stigmaria, Brongt., Class, d. ve'get. foss., p. 9. 

 1820. Variolar ia, Sternberg (iion Person). Essai flore monde 



prim., Vol. I., fasc. I., pp. 23 and 26. - 

 1826. Stigmaria, Sternberg, Essai flore monde prim., Vol. I., fasc. 



IV, p. 38. 



Rhizome of the Arborescent Lycopods, diverging from the base 

 of the trunk in four main branches. Shortly after separating from 

 the trunk each of the four primary arms bifurcates, giving rise to 

 eight rhizome branches ; at a distance of a few feet these again 

 bifurcate, forming sixteen branches. They do not again divide, 

 or only very rarely do so, but gradually terminate in a tapering 

 or blunt point. 



The outer surface of the cortex bears quincuncially-arranged 

 rootlet-scars, consisting of a slightly raised rim containing a hollow 

 circular depression placed about midway between the central 

 single vascular cicatrice and the outer rim. (Fig. 11.) Rootlets 

 long and bifurcating towards their extremity, or simple (I). 



The internal organization consists of a medulla, or pith, sur- 

 rounded by an exogenously developed zone of xylem enclosed in 

 a thick cortex. 



Medulla. — The Medulla is composed entirely of parenchyma, 

 extensions from which form the primary medullary rays. The cells 

 forming the pith seem to have been very delicate, and it is 

 extremely seldom that any of their remains are preserved. 



Xylem Cylinder. — In the earliest stage this consists of a ring 

 of very small vascular-bundles surrounding the Medulla. These 



1 Fossil Flora, Vol. L, p. 123, 1832. 



2 Previously employed for a genus of Lichens. {Fide, Brongniart, Class, 

 d. ve'get. foss. , p. 28. 



