158 



D. H. Scott. 



M a si en (1905) lias recently' worked out their relation to the stem 

 and finds that they were borne at the nodes, in much the same way 

 as the branches, but inserted at a somewhat lower level. The 

 structure is in all respects that typical of roots ; the main roots were 

 polyarch with a large pith, while the smallest rootlets had no pith 

 and were often tetrarch. The wide lacunar cortex indicates that 

 they grew in a watery substratum, and an interesting feature is the 

 l>resence of a double endodermis exactly as in the recent Egimetmn. 



The Fructifications of the Calamaria- 

 ceae are of several different types, nearly 

 all of which show an evident relation 

 to the wellknown strobilus of Equisetum 

 though usually of more complex organi- 

 zation. The best known form, wliich 

 appears in a number of species, may be 

 described under S c h i m p e r ' s name 

 Calamostachys (Fig. 5). This is charac- 

 terized by the fact that the axis of tlie 

 cone bears, in regular succession, whorls 

 of sporangiophores and of sterile bracts, 

 the former inserted midway between the 

 latter. The bracts in a verticil are often 

 just twice as many as the sporangio- 

 phores but sometimes the difference in 

 number is not so great. A curious point 

 is that the bracts of successive sterile 

 whorls are alternate with one another, 

 while the sporangiophores, considered by 

 themselves, are strictly superposed. 



The anatomy of the axis of the cone 

 is essentially that of a Calamarian twig, 

 though somewhat reduced in the case of the smaller forms of 

 Calamostachys, such as the common British Coal-Measure species, 

 C. Binneyana. A characteristic nodal structure only exists at the 

 insertion of the sterile bracts; its absence in the case of the 

 fertile verticils may be explained by an observation of Renault's 

 (1896) according to which the vascular supply of the sporangiophores 

 is derived from the bracteal node next below. The number of vascular 

 bundles in the axis is usually equal to that of the sporangiophores in 

 a verticil ; hence, when the bracts are twice as numerous, two traces 

 pass out at the node from each axial bundle. Immediately above their 

 exit a third small bundle, according to Renaulfs observations on 

 C. Zeilleri and C. GrancV Eiiriji , springs from the node, passes up 



Fig. 5. Calamostachys. Diagram 

 of cone in radial section ; ax, axis, 

 which hear successive verticils of 

 hracts {br) and peltate sporangio- 

 phores (sp); sm, sporangia borne 

 on the sporangiophores. As the 

 bracts are alternate with one 

 another their upturned tips are 

 oulj-^ shown in every alternate 

 verticil. 



