of Coal- Measure Plants. 



151 



Slide 4. Text-figure 5 ; PI. III. fig. 4, PL iv. fig. 11. 



This longitudinal section is figured by Binney, in his PL XV. 

 figs. 2 and 3 ; he refers it to Halonia regularis, while Section 1, 

 figured by Binney in his PL XIII. fig. 1, is described as Lepido- 

 dendron Harcourtii; but it is almost certain that both sections 

 were prepared from the same specimen. The two diverging steles 

 shown in Section 4 agree precisely with the two steles described 

 in Section 1 ; the other tissues of the sections are also in agree- 

 ment, and there can be little if any doubt that both sections were 

 cut from one and the same piece of branching stem. Section 4 

 illustrates very clearly the structure of the stele and the extra- 

 stelar tissues, also the manner of origin and structure of the 

 leaf-traces. The photograph shown in fig. 4, PL ill. includes the 

 edge of the corona x, succeeded by a few layers of short and very 

 dark coloured cells, beyond which are several rows of very distinct 

 parenchymatous elements, a — a, constituting the broad meriste- 

 matic zone (cf. fig. 3, PL III., a, a); external to this there is the 



Figure 5. Longitudinal Section through the Secretory Zone, s, the 

 Meristematic Zone, a, and the edge of the Corona, px. (Slide 4, x90.) 



