Proceedings of the Linnean Society of London - University Library

LIN?fEATf SOCIETY OF LOXDOX. 53
Shoetia, Terr, ifc Gray, in Am. Journ. Sc. ser. I. xlii. (1S42) 48 ;
et ser. II. xlv. (1868) 402.
Davidi, Franch. in Nouv. Avch. Mus. Par, ser, 11. x. (1887)
t. 13 B = Berneuxia thibetica, Decne.
galacifolia, Torr. S,- Graif, I. c.—Am. bor.
rotundifoUa, Makino, in Tokyo, Bot. Mag. ix. (1895) 327
et X. (1896) 22l=Scliizocodou rotundifolius, Maxim.
sinensis, Hemsl. in Hook. Ic. PI. t. 2624.—Yunnan.
thihetica, Franch. in Nouv. Arch. Mus. Par. ser. II. x. (1887)
54, t. 13 B (Z)rtyK7i)=Berueuxia thibetica, Decnc.
uniflora, Maxim, in Bull. Acad. Petersh. xvi. (1871) 225.
—Japon.
II.
The Origin of Gymnosperms.
By Prof. F. W. Oliver, F.E.S., F.L.S.
[Eead lotli March, 1906.]
The inA'-estigations of Hofmeister have been regarded as settling
once for all the general relation of affinity between the Gymnosperms
and Vascular Cryptogams. Critical analysis of this work
and later contributions in the same field have led to the recognition
of several distinct lines of descent Mithin the latter class, and at
one time and another each of these lines has been favoured as
that from which the Gymnosperms arose. In recent times, the
balance of opinion has set in the direction of the Ferns, the point
of closest contact being found in the Cycads. The view has
gained material support through the discovery of multiciliate
spermatozoids in the last-named group and in Ginlr/o, as well as
from the recognition of the existence in Palaeozoic times of an
extensive plexus of forms (the Cycadofilices) which, whilst
retaining tlae habit and many of the structural peculiarities of
Ferns, show a distinct advance in the direction of the Cycads.
Now that evidence has come to light proving that many of the
forms there included were seed-beai'ing plants, the foundation of
a new Class, the Pteridospermeae, has been judged expedient for
these Spermopbytes which have so much in common with the
Ferns.
As matters are shaping at the present time, it would appear
that certainly a preponderating number of so-called Palteozoic
" Ferns " are in reality Pteridosperms which have been hitherto
confounded with true Ferns in view of their frond-like habit and
lack of distinguishing organs of reproduction. The existence of
a great reserve of supposed Ferns in the older rocks has served as
a material bulwark to the ilofmeisterian doctrine of the passage
of Pteridophytes into Sperm.ophytes. But if the Palteozoic is in
reality the "age of Pteridosperms'" rather than the "age of
;