Seward's “ Fossil Plants." 265 
come as a shock to the geological reader, but the botanist will 
welcome the extinction of a myth. 
The 250 pages devoted to the Lycopods begin, according to the 
author’s custom, with a sketch of recent forms, illustrated by some 
characteristic figures of habit and structure, which will be a great 
help to the non-botanical student. The fossils start with the 
Isoetaceae and Pleuromeia, a curious Triassic genus which has been 
regarded as connecting the Lepidodendreae with Isoetes. The 
author appears to accept the statement that the sporangium in 
Pleuromeia is on the lower side of the sporophyll, a character which 
scarcely seems consistent with Lycopod affinities. 
Next comes an account of the herbaceous fossil Lycopods, our 
knowledge of which has increased a good deal in a short time. It 
is curious that there is no known case of homospory among these 
plants, unless it be in the Mesozoic Naiadita. 
Chapter XV. (“Arborescent Lycopodiales ”) includes the genus 
Lepidodendron, in the widest sense, Lepidophloios being treated as 
a sub-genus. 
The anatomy of the stem is described in detail in Lepidodendron 
vasculare , Binney (L. selaginoides, Carruthers). The difficulty that 
the cells of the cambium and those of the secondary wood do not 
usually fit on to each other is pointed out; this fact probably 
indicates that growth had ceased naturally some time before death. 
In the section on Ulodendron and Halonia the author inclines 
to Mr. Watson’s view that the ulodendroid scar marks the insertion 
of a deciduous branch and not of a cone, a view confirmed by 
Renier’s recent work. He is also sceptical as to the cone theory in 
the case of Halonia, chiefly on the ground of the difference in stelar 
structure between the tubercle and the axis of the cone. Neither 
does he believe that the distinction between Halonia and Ulo¬ 
dendron is of generic value. 
Throughout the account of the anatomy of Lepidodendron 
Professor Seward adheres to his term “secretory zone” for the layer 
corresponding in position to the phloem. His scepticism as to the 
presence of true phloem in these plants serves, at any rate, to call 
attention to points in the anatomy which need fuller investigation. 
In accordance with his view of Ulodendron, the author 
discredits the idea of sessile cones, and believes that all cones were 
borne terminally on slender shoots, as is known to have been the 
case in some forms. 
The value of Maslen’s work on Lepidostrobus is fully recognised ; 
in discussing Spencerites, the author attaches importance to Lang’s 
comparison between this type of fossil cone and the recent 
Lycopodium cernuum, a point on which some difference of opinion 
prevails. 
In the chapter on Sigillaria an interesting sketch of the old 
controversy between Williamson and the French school is given in 
a few words. The victory rested with Williamson who successfully 
maintained the cryptogamic nature of the genus and its close 
affinity with Lepidodendron. Our knowledge of the internal 
structure of Sigillaria has grown rapidly of late years, owing to the 
work of Bertrand, Kidston, and Arber and Thomas. Professor 
Seward publishes, for the first time, figures of the anatomy of S. 
elongata described by Bertrand in 1899. 
In chapter XVII. the somewhat difficult subject of the rhizomes 
and roots of fossil Lycopods is dealt with. The author points out 
that the evidence for the connection between Stigmaria and the 
Lepidodendron stem is “still very meagre” (p. 233). He inclines 
