230 Professor Seward's “ Fossil Plants .” 
REVIEW. 
“FOSSIL PLANTS.” A Tbxt-Book for Students of Botany 
and Geology. By A. C. Seward, F.R.S. Vol. III. 1 
Pteridospermese, Cycadofilices, Cordaitales, Cycadophyta. 
With 253 Illustrations. Cambridge, at the University 
Press. 1917. Pp. xviii and 656. Price 18/-. 
P ROFESSOR SEWARD’S great work is now nearing its 
conclusion, for Vol. IV, completing the book, is already in 
the Press, and will it is hoped be published before the end 
of the year. The present volume is dedicated to the memory of 
the author’s friend, Charles Rene Zeiller, whose death two years 
ago was so irreparable a loss to Fossil Botany. His portrait forms 
the frontispiece. 
The subject of geographical distribution, on which the author 
is so well qualified to speak, is reserved for connected treatment in 
a separate book. As will be seen from the title, the groups of 
plants described in Vol. Ill are of the utmost importance, and are 
perhaps those of the greatest interest in the present position 
of Palseobotany. While the Pteridosperms, Cycadofilices and 
Cordaitales were essentially Palaeozoic plants, the Cycadophyta 
were dominant in the Mesozoic period and still survive. It is 
needless to say that no such ample and connected account of these 
great classes of plants has appeared before. The volume is thus a 
contribution of the highest value to the study of the plants of 
past ages. 
The opening chapter (XXVIII) is appropriately devoted to an 
excellent account of the recent Cycads. The question of the 
mesareh foliar bundles is discussed, with reference to the primary 
or secondary nature of the centrifugal portion of the xylem. The 
point, though interesting, is perhaps less essential than is some¬ 
times supposed, for primary centrifugal xylem tends to become 
merged in the secondary, as is well shown in the leaf-trace strands 
of the Cordaitales. 
The next chapter is on the Lyginopterideae. The generic name 
Lyginopteris, Potonid, is adopted instead of the familiar Lygino¬ 
dendron, essentially on the ground that the name Lyginodendron 
“ was first used for a specimen which has nothing to do with the 
plant usually spoken of as Lyginodendron oldhamiutn ” (p. 38). 
This change of nomenclature may be somewhat unwelcome to 
British palseobotanists, but there are strong grounds for it, especially 
in view of the fact that Gourlie’s name Lyginodendron is still 
employed in its original sense, for certain casts of Lepidodendroid 
stems. This double usage is confusing and illegitimate, and it is 
probably best to make up our minds to adopt the unambiguous name 
Lyginopteris. 
Binney’s type specimen (1866) was first figured by Dr. Arber 
in 1902, and his figure is reproduced on p. 39. With reference to 
the microsporangia, the bilocular sporangium shown in Fig. 407, A, 
1 Vol. II of this work was reviewed in the New Phytologist in 1910, 
9, p. 264. Vol. 1 was published in 1898. 
