LEAVES OF CALAMARIEAE 39 



sheath at the base. Each leaf is traversed by a vein, 

 and further to the interior the commissural vascular 

 bundles of the node are visible. It is possible that in 

 many cases the sheath became split up as the stem 

 increased in thickness. 



Immediately below a node the cortex of the stem 

 shows in some specimens a number of prominent ribs, 

 corresponding to the bases of the verticillate leaves 



Fig. 13. — Catamites, sp. Part of transverse section close to a node, showing the prominent 

 leaf-bases, Lb. x, secondary wood ; /, fisttilar pith. Magnified. From a section 

 lent by the late Mr. J. Butterworth of Shaw. (G. T. G.) 



which sprang from the node. This is well shown, in 

 transverse section, in Fig. 13. 1 



As regards the anatomical structure of the leaves of 

 the Calamites there is comparatively little to be said. 

 In Calamites itself the simple acicular leaves were each 

 traversed by a single nerve (see Fig. 12) ; in some of 

 the other forms, as in Calamadadus? according to 



1 For the use of the specimens illustrated in Figs. 12 and 13 I am 

 indebted to the late Mr. John Butterworth of Shaw. 



2 The foliage of Calamarieae will be further described, as regards its 

 outward aspect, in the following chapter. 



