934 PROFESSOR W. C. WILLIAMSON AND DR. D. H. SCOTT ON THE 
opportunity, through the kindness of M. Zemter, of thoroughly examining his 
original specimens, and was able completely to confirm his conclusions. 
We propose first to give a general account of the organization of the strobilus, as 
shown in the English specimens, in which alone the internal structure is preserved. 
The facts already known will be briefly recapitulated, while some additional points of 
interest, which have been revealed by our renewed examination of the specimens, will 
be described more fully. Finally, we shall state the reasons which have induced us 
to accept M. Zeruier’s conclusion that this strobilus is the fructification of a 
Sphenophyllum. 
For the present we propose to retain the specific name originally given to the 
English specimens, which we shall therefore describe as Sphenophyllum Dawsoma. 
General Morphology. 
The strobilus consists of a somewhat slender axis (attaining 2°5 millims. in diameter) 
bearing a number of successive verticils of coherent bracts. The largest number of 
whorls preserved in any of our specimens is 8 (in C.N. 1898 x, part of which is 
represented in Plate 85, fig. 54) ; the total number was no doubt much greater. 
The coherent portion of the bracts, forming the disc of previous memoirs, extended 
for a distance about equal to the diameter of the axis. It then divided up into the 
free bracts, or “disc-rays.” The latter had a somewhat lanceolate form, broadening 
out for some distance from the base, and then tapering again towards the apex. On 
leaving the axis the bracts take an obliquely upward course, curving rapidly towards 
the apex of the strobilus, until their direction is nearly vertical (Plate 85, fig. 54). 
The free limbs of the bracts were of great length, as is shown by the fact that in 
transverse sections we may find as many as six overlapping whorls, proving that the 
extreme vertical length of the bracts must sometimes have been equal to about six 
internodes, giving an extreme absolute length of perhaps 12 millims.* 
The number of bracts in a verticil could not be determined with certainty ; appa- 
rently it was about fourteen in some of the smaller specimens, and not less than 
twenty in the larger. 
From the position of the overlapping tips it appears that the bracts of successive 
whorls alternated with one another. This is somewhat surprising, for the leaves in 
the vegetative verticils of Sphenophyllum were superposed. This is, however, no 
argument against the identification of our specimens with Sphenophyllum, for in 
M. Zetiuer’s strobili, borne on the stems of typical Sphenophyllum crucifolium, the 
alternation of the bracts is still more evident. 
The sporangia are not borne directly on the bracts, but each is seated on the end of 
a long pedicel or sporangiophore. The pedicels are twice as numerous as the bracts ; 
* M. Zeriur’s estimate, based on the figures of Memoir XVIII., is 8 millims. Some of his specimens 
of S. cuneifolium have bracts 10-13 millims. in length, See his Memoir above cited, p. 21, 
