RESEARCHES OX THE CARBONIFEROUS FLORA. 259 



those grouped together under the name Astromyelon, in his 

 part xii. We now know that these organs are all roots and 

 rootlets of Calamites. 



Passing on to Calamarian fructifications we find that 

 memoir v. (1873) contains some additional illustrations of 

 the cone now known as Calamostachys Binneyana, already 

 described by Binney and Carruthers (41 and 42). These 

 authors had already recognised its true affinities as a form of 

 Calamarian fruit. Williamson was unfortunately misled by 

 a mistake as to the anatomy of the axis, and for many years 

 refused to allow that Calamostachys had anything to do with 

 Catamites. Ultimately he corrected this error himself, but 

 it affects all his work on the subject up to 1890. The point 

 is this : our author thought that the axis of the strobilus in 

 Calamostachys was traversed bv a solid strand of wood, 

 something like that of a Sphenophyllum or, to use his nomen- 

 clature, Asterophyllites. In reality there is no resemblance 

 in the anatomy of the two genera, for Calamostachys has in 

 fact a well-developed pith, not to mention other differences 

 (15 and 29). This anatomical error logically led Williamson 

 to the conclusion that Calamostachys had much closer affini- 

 ties with Asterophyllites (which he then regarded as Lycopo- 

 diaceous.) than with Calamites. In memoir v., however, some 

 interesting additions were made to our knowledge of the 

 fruit, the most important being the first observation of the 

 young spores still enclosed in their mother-cells, the re- 

 mains of which had been mistaken by a previous observer 

 for ekiters. 



In 1879 (mem. x.) further valuable specimens of 

 Calamostachys were recorded. In one of the sections 

 figured (pi. 15, fig. 15) the carinal or fascicular canals, so 

 characteristic of Equisetaceous plants, are distinctly shown 

 in the axis of the strobilus, but their significance was over- 

 looked. 



In the next year (mem. xi., 1880) a most important 

 discovery — that of a heterosporous Calamostachys — was re- 

 corded. This form was at first referred to the original 

 species, C. Binneyana, though subsequently shown to be 

 specifically distinct. The author said: "This discovery 



