FRUCTIFICATIONS OF CALAMARIEAE 51 



have a type which is essentially the same as that of 

 Equisetum, e.g. Archaeocalamites, for here the sporangio- 

 phores are present alone, without any bracts at all, or 

 only at long intervals (Fig. 24, B). In other cases 

 cones have been found which even more exactly 

 resemble those of recent Equisetaceae. 



2. Calamostachys. — I will now shortly describe the 



8m 



Fig. 18. — Calamostachys Binneyana. Transverse section of cone, passing through a whorl 

 of six peltate sporangiophores, sp. sm. sporangia attached to the peltate laminae of 

 the sporangiophores. x 16. Will. Coll. 1020. (G. T. G.) 



British species of Calamostachys, the genus with alter- 

 nating and equidistant whorls of bracts and sporangio- 

 phores. The affinities of the genus have been very 

 much disputed in the past, but are now cleared up. 

 We will first take the anatomy of the axis of the cone, 

 as shown in the commonest British form, Calamostachys 

 Binneyana. The axis is traversed by a central cylinder 

 (see Fig. 17), with a distinct and persistent pith (see 

 Fig. 1 9). Surrounding the pith are the vascular bundles, 



