268 
Seward's “ Fossil Plants." 
Osmundacese, vve must he prepared for the existence of a Zygopteris 
with a solid xylem like that of Thamnopteris : “ such a discovery, 
in fact, we hopefully anticipate.” This prediction has now been 
fulfilled by Mr. Gordon’s discovery of the stem of Diplolabis, a 
genus closely allied to Zygopteris (p. 448). 
Professor Seward concludes the chapter as follows: “ The 
conclusion arrived at is that while the Coenopterideae foreshadow 
in some of their characters more than one group of more recent 
Ferns, some at least of their members afford convincing evidence 
of the correctness of the view—which is also that of Dr. Kidston 
and Mr. Gwynne-Vaughan—that the Osmundaceae and the Ccenop- 
terideae are offshoots of a common stock ” (p. 472). 
As regards the Hydropterideae, Nathorst’s discovery of sporo- 
carp-like bodies in association with the Rhaetic Sagenopteris, 
strengthens the belief that this genus may really, as the form of the 
frond suggests, belong to the Marsiliaceae; otherwise there is no 
trustworthy evidence of pre-Tertiary Water-ferns. 
Chapter XXVII, the last in the volume, is headed “Genera of 
Pteridosperms, Ferns and Plantce incertce sedis.” “ Some of the 
genera, the smaller number, are no doubt true Ferns ” ; most of 
them are in all probability Pteridosperms or Cycadophytes. This 
chapter is intended to clear the ground, “in order that the Chapter 
in Vol. Ill devoted to this important group may be limited to more 
completely known types ” (p. 484). Among the more or less 
doubtful genera dealt with is Glossopteris, “ a characteristic member 
of a Permo-carboniferous flora which flourished over an enormous 
area”—India, S. Africa, Australia, and S. America. The interpre¬ 
tation of the characters of the rhizome (Vertebraria) is still quite 
uncertain, but if Blechnoxylon, with its zone of what appears to be 
secondary wood, is rightly referred to Glossopteris, we have a 
possible indication of Pteridospermous affinities. Otherwise the 
sporangia observed by Mr. Arber in association with the scale-leaves 
of G. Brownii are the chief point of botanical interest, in a group 
which has hitherto chiefly appealed to the geographer and the 
stratigraphical geologist. It is a suggestive fact that the scale-leaves 
of the allied Gangamopteris have been found associated with 
Gymnospermous seeds. 
In looking through the long list of frond-genera described in 
this chapter, it is curious to see in how few cases there is any good 
evidence of their belonging to Ferns ; either there is no evidence 
at all, or it is on the side of spermophytic affinities. It is interesting 
to find among the Mesozoic fossils a number of doubtful genera, 
which may well have been belated Pteridosperms, or perhaps 
Cycadophytes of unknown families. A promising field for research 
here remains to be explored. 
The volume as a whole is a perfect mine of information, brought 
thoroughly up-to-date, and sifted with the sound judgment which 
is characteristic of the author. It is beyond comparison the best 
text book for the groups to which it relates, and will of course be 
indispensable to botanists. The numerous illustrations are of the 
greatest service to the reader, and in view of their abundance, we 
cannot complain if, in a few cases, they are more diagrammatic 
than we might have wished. 
We shall look forward with great interest to the appearance of 
Vol. Ill, in which some questions of very deep importance to the 
student of evolution will come up for discussion. D.H.S. 
