FOSSIL PLANTS. 55 



description of this strobilus by the same writer, and, follow- 

 ing this, Zeiller 1 published a note in the Comptes Reudus, 

 in which he points out the very close resemblance between 

 certain specimens of Sphenophyllum cuneifolium and Bow- 

 mannites Daivsoni. In a short account of Sphenophyllum 

 in Nature, 1892, Williamson agrees with Zeiller as to the 

 probable identity of Bowmannites and Sphenophyllum} 

 Finally, in 1893, Zeiller reviews the whole case, and demon- 

 strates by a series of exceedingly successful photographs, 

 and his usual clearness of description, the very striking cor- 

 respondence between the English specimens, with their 

 clearly preserved structure, and the French and Belgian 

 specimens of Sphenophyllum strobili. Want of space does 

 not allow of a complete abstract of Zeiller's concise descrip- 

 tion of the histology of Bowmannites, as interpreted by Prof. 

 Williamson. 



In Bowmannites Dawson i we have a central axis bearing 

 verticils of bracts ; the bracts of each whorl are fused to- 

 gether at the base in the form of a continuous " nodal disc," 

 the free portions of the disc being prolonged obliquely up- 

 wards for two or three internodes. Between the verticils 

 there occur numerous sporangia arranged in a multiseriate 

 manner, in such a way that they form a series of circles 

 arranged round the axis of the strobilus. The rings of 

 sporangia are not concentric, but the centre of each suc- 

 cessive circle reaches a higher level on the axis of the stro- 

 bilus, the height increasing with the increase in length of 

 the radius of each circle. The sporangia are ovoid in form, 

 and each is supported at the tip of a slender pedicel which 

 is given off from the upper surface of the " nodal disc " ; at 

 the point of junction of each pedicel with its sporangium, 

 the cells of the former increase somewhat in size, and ap- 

 pear to constitute a group of specialised cells analogous to 

 the annulus of fern sporangia. The spores are of one kind, 

 and present a characteristic surface appearance due to the 

 presence of slightly projecting and anastomosing ridges. As 



1 Comf>t. Rend., vol. cxv., 1892, p. 141. 



2 Nature, vol. xlvii., p. 11. 



