942 PROFESSOR W. C. WILLIAMSON AND DR. D. H. SCOTT ON THE 
will only call attention to one case, that of the fructification of Sphenophyllum 
trichomatosum, Stur, recently described by Mr. Kipston.* 
The author states (p. 60) that ‘“ the oval sporangia (which have thick walls, 
as indicated by the amount of carbon they possess) stand upright on the bracts — 
a short distance from their point of attachment to the cone.” This statement is quite 
exact as regards the two sporangia to which Mr. Krpsron is specially referring (see 
his fig. 14), but from his other figures it appears that the relation of the sporangia to 
the bracts, and to the axis, was very inconstant. Sometimes they appear exactly in 
the axil, sometimes at a distance from it; in certain cases they are shown in close 
contact with the upper surface of the bracts, while in others they are quite separate 
from them. These variations would find an adequate explanation if the sporangia 
were borne on pedicels, which would allow of a considerable degree of displacement. 
It must be remembered that the specimens of Sphenophyllum Dawsoni are, with 
two exceptions to be mentioned immediately, the only ones known in which the 
internal structure of the strobilus is preserved, while among the specimens in the form 
of impressions, those described by M. ZEILLER would appear to be by far the most 
perfect. The morphology of the strobilus must necessarily be interpreted in the light 
of those specimens in which alone it is clearly exhibited. 
Two silicified fragments of fructifications, referred to Sphenophyllum, have been 
discovered by M. Renauur. One of them has been mentioned above, and is described 
in M. Zeriuer’s Memoir (loc. cit., p. 28). Its organization agrees well with that of 
S. cuneifolium and S. Dawsoni. The other fragment has been interpreted by 
M. Renavtr as demonstrating the heterospory of Sphenophyllum.t M. ZEtLLER has 
pointed out that in this specimen the sporangia were certainly borne on pedicels 
(Joc. cit., p. 34). His interpretation of the supposed macrosporangium is different 
from that of M. Renauur. M. Zeinuer regards the “ macrospore ” as being in reality 
a part of the sporangial wall, while the supposed wall of the macrosporangium belongs, 
in his opinion, to the pedicel. One of us (D. H. Scorr) was enabled through 
M. Renavtr’s kindness, to examine the specimen in question, and was disposed to 
accept M. ZEILLER’s interpretation. 
Although we cannot regard the evidence derived from this specimen (which is 
imperfectly preserved) as by any means sufficient to establish the fact of heterospory, 
yet we fully allow the possebility that heterosporous species of Sphenophyllum may 
have existed. That both heterosporous and homosporous species may occur, within 
the limits of a single genus, is sufficiently proved by the case of Calamostachys. 
The morphology of the strobilus of Sphenophyllum cannot be fully interpreted 
until the true homologies of the sporangiophores are established. Four views appear 
possible :— 
* «Proc. Royal Phys. Soc. of Edinburgh,’ vol. 11, 1891, p. 56. 
+ ‘Ann. des Sci. Nat., Bot.,’ Sér. 6, vol. 4, 1877, p. 303, Plate 9, figs. 9-11; ‘Cours de Bot. Fossile,’ 
vol. 2, p. 102, Plate 15, figs. 7 and 8, Plate 16, fig. 3. 
