The Fossil Plants of the Coal Measures. 103 



Macrosporangial. 



C— p. 296, Fig. 28, C.N. 524. 



BB.-p. 26 PI. 8, Fig. 51-52. 

 Macrospores. 



C. — p. 296, Fig. 27X, 28x, C.N.524, 



Type of Lepidodendron fidiginosuni. Will ; L. Harcoiirtii of 

 the Memoirs prior to i88y. 



Young branches (C.N. 379) less easily identified than 

 older ones ; approaching young forms of L. Harcoiirtii, 

 from which they differ in the absence of the Diploxyloid 

 leaf-trace characteristic of the latter plant. Young 

 twigs apparently large ; the smallest yet identified being 

 "6 of an inch in diameter, including its leaves. Medulla 

 conspicuously developed even in young growths. The 

 primary tracheal cylinder large and conspicuous, giving off 

 great numbers of equally conspicuous, symmetrically 

 arranged, leaf-traces. The most distinctive zone of the 

 Cortex is the innermost one, the component cells of which, 

 especially in the older branches, tend to arrange themselves 

 in radiating rows. The cells of the more external layers of 

 small size and very uniform aspect, causing the transverse 

 sections to assume a remarkably sooty hue, which contrasts 

 strongly with the brighter, more translucent, aspects of 

 other allied forms. In many stems of advanced growth we 

 find in the innermost Cortex, but separated from the 

 periphery ol the primary tracheal cylinder, a very rudimen- 

 tary form of secondary xylem strand, and what exists is 

 arranged in radial lines, symmetrical with those of the cells 

 of the innermost Cortex ; but these lines are very irregu- 

 larly distributed, a group of them accumulated conspicu- 

 ously at one part of the circle, whilst at other parts they are 

 wholly wanting or only represented by one or two isolated 

 radial lines. Vertical tangential sections through these lines 

 of tracheae shew that the perpendicular course is irregularly 

 undulated instead of their being straight and parallel. Be- 



