66 Dr. W. C. Williamson on 



SPHENOPHYLLUM. Brongniart 

 E. — p. 42, Fig. 26, Owens College Museum. 



CALAMOSTACHYS BINNEYANA. 



CALAMOSTACHYS. Schimpr. 



CALAMOSTACHYS BINNEYANA. Schimper, 



CALAMODENDRON COMMUNE. Binmy, 



VOLKMANNIA BINNEYI. Carruthers. 



Vasculo-cellular Axis.* 



Medulla.^ 



C.N. looi. C.N. 1016. 



K.— p. 503, Fig. 13a, C.N. 1039. p. 503, Fig. 15a, C.N. 1043. 



P.— p. 160, Fig. 7a, C.N. 1004. Fig. 8a, C.N. 1008. 



Tracheids. — Longitudinal Section. 

 K.— Fig. 13a. 



Transverse Section. 



E.— p. 61, Fig. 38, C.N. 989. p. 72. 



P.— p. 160, Fig. 7b, b', C.N. 1004. Fig. 8a, C.N. 1000. 



Exogenous growth of ? 

 E.— p. 72, Fig. 38. 

 K.— p. 504-5, Fig. 16, C.N. 1016. 



Alternation of Nodes. 



Sterile. 



E.— p. 59, Fig. 33, C.N. 1045*. Fig. 34, C.N. 994. 

 K.— p. 503. Fig. I3e. 



Fertile. 



E.— p. 60, Fig. 36, C.N. 991. 

 K.— p. 503, Fig. 13d, C.N. 1039. 



* Vascula-meduUary axis. There has been much difficulty in defining the structure 

 of this axis, which varies much in different specimens. In Memoir E, Figs. 37-38, we have the 

 axis of the specimen C.N. 989. Its centre is probably cellular, not vascular as described in 

 the Memoir ; but it is surrounded by a zone of radially disposed Tracheids, of which the 

 orientation is specially related to the three points d, d, d, as described in the Memoir, and 

 indicating some relationship to the triquetrous vascular axis of the Asterophyllites, described 

 in the same Memoir. Similar conditions are seen in other specimens in my cabinet — markedly 

 so in C.N. 1014 and 1016, in which the central medulla is distinctly cellular, but in which the 

 peripheral vessels are as distinctly arranged in three externally convex groups. An identical 

 arrangement appears in the Calamostachys Ludwigi figured by Herr Weiss in his " Steinkohlen 

 Calamarien II." Taf. 24. In another transverse section (C.N. 1094) these tracheids are clustered 

 at four angles of a somewhat quadrate section. Other minor features suggest that more than 

 one species may be comprehended under the name of Calamostachys Binneyana. 



t When writing Memoirs E and K, I had failed to discover this organ. The central 

 axis was erroneously described as wholly vascular, the elongated medullary cells being 

 mistaken for Tracheids. 



