Knowledge of Lyginodendron . 85 
it would seem that Lyginodendron robustum , Lyginodendron 
Oldhamium , Lyginodendron anomalum , and Cycadoxylon 
Fremyi , possess such characters in common as distinctly 
point to a close relationship. 
Our incomplete knowledge of the last named species, as 
compared with our much more complete acquaintance with 
Lyginodendron Oldhamium , renders it unprofitable to press 
the comparison very far ; but it is probable that we may 
be able, with more extended knowledge, to classify many of 
the Palaeozoic types into more definite groups founded on 
the true relationship as expressed by the possession of 
cycadean characters. 
The structure of Medullosa gigas , Ren., as described in 
the Flore fossile d’Autun et d’Fpinac, presents an exceed- 
ingly close agreement with that of Lyginodendron (Flor. foss., 
PL LXXI). A more complete comparison of the various 
Palaeozoic plants possessing cycadean affinities must, however, 
be deferred. 
My thanks are due to Mr. George Murray, Keeper of the 
Botanical Department in the British Museum, for permission 
to have several sections prepared from material in his charge ; 
to Mr. Gepp, of the British Museum, I am indebted for the 
photographs reproduced in Plate V ; and to Dr. D. H. Scott 
for valuable criticisms and suggestions. 
EXPLANATION OF FIGURES IN PLATES 
V AND VI. 
Illustrating Mr. Seward’s paper on Lyginodendron. 
All the sections have been prepared from the same specimen of Lyginodendron 
robustum , sp. nov., and are in the Botanical Department of the British Museum. 
PLATE V. 
Fig. 1. Transverse section of the stem, showing the thick centrifugal wood 
with apparent annual rings, and the tissues of the pith, with secondary parenchy- 
matous tissue at p. 
