CALAMARIEAE. 327 



spores, which show the triradiate ridge. From their size I should suppose 

 them to be microspores, but this is not certain, for a similar spike, which will 

 be described presently, containing both kinds of spores, shows us that the 

 differences in size need not be verj' great, and that macrospores also may be 

 formed in large numbers in a sporangium. 



We have also learnt something respecting the anatomical structure of 

 the axis l . Rind and pith partially preserved are parenchymatous, and are 

 separated from one another by a rather broad closed ring of wood nearly 

 triangular in shape. I was unable to form a clear idea of the character of 

 the imperfectly preserved medullary sheath from the original sections sent 

 me by Weiss for my inspection. A preparation of Williamson 2 from the 

 nearly allied Calamostachys Binneyana will perhaps supply what is wanting 

 on renewed examination. What there was to be seen was quite in accord- 

 ance with the structure of Calamitae, but I would rather not at present 

 venture on positive and detailed statements. 



A second species, the organisation of which is well known, Calamo- 

 stachys Binneyana, Schpr., was first figured by Carruthers 3 as Volkmannia 

 Binneyi, then by Binney 4 as the fructification of his Calamodendron com- 

 mune, and lastly and repeatedly by Williamson 5 . It is smaller than the 

 preceding, and while the structure is in essential points the same it is 

 distinguished by the much smaller development of its woody body, and 

 especially by the circumstance that the leaves of the sterile whorls are seen 

 to be united to one another almost as high as the point where they bend 

 over, and therefore form on the tangential section transverse connected 

 laminae ensheathing the sporangiophores, as is represented in Binney 6 . So 

 far all these spikes, which are apparently plentiful in the English calcareous 

 nodules, agree with one another. Nevertheless both to myself and Weiss 

 it appears doubtful whether they really all belong to one another, whether 

 different species of similar habit have not been included under the one 

 name. Williamson 7 , for example, describes a fragment of a spike which 

 has macrosporangia below and microsporangia above. The two are exactly 

 alike and contain numerous spores, which are distinguished merely by a 

 moderate difference in size, the larger having about three times the diameter 

 of the smaller. Now it is very remarkable that Binney, though he figures 

 the radial section of the base of a spike 8 , found no such macrosporangia in 

 it, and it may be suspected that there were none in this particular spike. 

 And on the other hand in the collection of sections in the Botanical De- 

 partment of the British Museum I have seen similar sections of spikes which 

 appeared to contain only macrospores, and these seemed to show the three 



1 Weiss (5), t. 24. a Williamson (1), X, t. 16, f. 16. 3 Carruthers (15). * Binney (1), 

 I, tt. 4, 5. 5 Williamson (1), v, t. 6 ; x, t. 15, ff. 13-17 ; XI, t. 54, ff. 23-26. 6 Binney (1), 



I, t. 5. T Williamson (1), XI, t. 54. 8 Binney (1), I, t. 5, f. 4. 



