Oliver . — The Ovules of the older Gy nmo sperms. 459 
that cannot be considered, owing to the lack of data. It is 
just possible, of course, in view of the distinctly Cycadean 
tendencies of the Cordaitean seeds themselves, that this 
parallelism also involved the pollen ; or, on the other hand, 
as D. H. Scott points out, the pollen-grains of Cordaites may 
have been a stage nearer the Cryptogamic microspore than 
those of Cycas or Ginkgo h 
From what has been stated above it is evident that the 
Platyspermic (or Cordaitean) seeds must be carefully discrimi- 
nated from the Radiospermic. The former show a marked 
approach to a parallelism with the ovules of recent Cycads, 
whilst the latter appear to exhibit more general and perhaps 
more primitive characters. That all these seeds belonged to 
plants of common * if remote ancestry there can be little 
reasonable doubt in view of their general striking unity of 
organization. The types of seed possessed by these remote 
ancestors may have to a certain extent combined the characters 
of both these groups, as in the hypothetical Figures 1 and 10. 
Actually the seeds represented in these figures are symmetrical 
about a principal plane, but that modification has been intro- 
duced for purposes of comparison with certain recent seeds ; 
here, regarding them as possible ancestral forms of the Radio- 
spermeae and Platyspermeae, this implied flattening may be 
disregarded. 
2. Lagenostoma. 
This seed, belonging to the lower coal-measures, was in 
point of time considerably earlier than Brongniart’s seeds 
from the French permo-carboniferous. Nevertheless, it shows 
marked and unusual peculiarities, and evidently stands some- 
what apart from the generality of palaeozoic seeds. In 
consequence, it seems fitting to treat it apart from the other 
seeds of the primary rocks, though regarding it as a type 
analogous to the Cycad in certain respects. 
The general organization of this seed is known from Wil- 
1 D. H. Scott, loc. cit., p. 435. 
