Pteridosperms and Angiosperms. 241 
seed-pedicel just below the chalaza.' This, in guarded terms, is 
compared with the cupule of Lyginodendron (Lagenostoma). 
No doubt the cupule of Lyginodendron holds out the possibility 
of being the kind of structure that might have been the precursor of 
an enclosing Angiospermic carpel in some lines of descent, as Mr. 
Arber has pointed out; 2 whilst in other cases, especially where there 
is crowding as in Cycadeoidea, or (to go further afield) in the 
analogous case of the aril of Phyllocladus, this supposed primordial 
carpel might have dwindled to the insignificance of a vestige. 
It is quite conceivable that in some undiscovered, but allied, 
branch of Cycadophyta this organ might have increased in importance 
by the assumption of stigmatic functions ; if so, this hypothetical 
group would make a strong bid to be the real Pro-Angiosperms. 
At present, however, it is premature to draw any conclusions 
whatever from an organ so obscure as the cupule-like envelope 
of Cycndoidea, for the whole question being of the most fundamental 
and far-reaching significance, conclusive evidence alone can serve 
our purpose. When the developmental stages of Cycadeoidea 
come to he worked out, perhaps fresh light may be thrown on the 
question of the existence of a “cupule” in the group. 
Hence it would appear that whilst the latest work on 
the flower of Cycadeoidea brings the Filicinean seed-line appreciably 
nearer to a junction with the Angiosperms, there still remains a 
hiatus to be bridged. Further back, the Pteridosperms shew us the 
lines along which the Cycadophyta may have arisen from the archaic 
Ferns (the Primofilices of Arber), of which the Botryopterideje is 
the only group at all well recognised. But here again westillawait 
the linking forms, representatives shading down into the Ferns 
below and into the Cycadophytes above. 
Apart from the capriciousness of fossilisation, one is inclined 
to suspect that such types may have been rare in the actual floras. 
And further, when—by whatever means—such a one had given 
origin to the beginnings of a new class, extinction would await the 
parent form when subject to competition with its offspring. This 
perhaps is the explanation of the survival to our days of the non- 
Angiospermous branch of the Cycadophyta: unlike the Bennet- 
titales they evaded direct competition with the Angiosperms. 
1 G. R. Wieland, loc. cit., pp. 120 and 234. 
? E. A. X. Arber. “On Some New Species of Lagenostoma.’’ 
Roy. Soc. Proc., Series B., Vol. 76, p. 256. 
