Knowledge of Lygin odendron. 77 
presenting, in fact, an appearance very similar to that already 
noticed in certain parts of the large stem 1 . Sections of Lygino - 
dendron Oldhamium occasionally show an apparent continuity 
between the centrifugal and centripetal xylem-bands, the 
primary xylem being sometimes disturbed and much less 
obvious than in other parts of the section. 
In the remarks on two sections (Nos. 1129 and 1130) 
written in the catalogue of the Williamson Collection, the 
great breadth of the medullary rays is pointed out ; the 
secondary wood in the specimens is very similar to that 
in Nield’s stem, but the tracheids in the former are slightly 
wider. The same sections show also the curving of the inner 
ends of the tracheid-bands, as in the large stem ; the groups 
of primary xylem in these sections present a crushed appear- 
ance and are separated by wide intervals. The general 
appearance of the sections is exceedingly close to that of 
Nield's plant 2 . The comparison of several specimens of 
Lyginodendron Oldhamium with the stem under discussion, 
as regards the manner of occurrence of the primary xylem, 
renders it probable that the absence of any direct proof of 
the existence in the latter of undoubted primary elements by 
no means negatives the idea that the plant originally 
possessed primary xylem-strands similar to those of the 
former species. A tangential section through the wood of 
Lyginodendron Oldhamium presents the appearance of longer 
and narrower medullary rays than those represented in PI. V, 
Fig. 7 ; but although there is a fairly constant difference 
in this respect, by examining a sufficient number of sections 
it is possible to match fairly closely the various structures in 
the two sets of specimens. 
The general conclusion arrived at may be briefly stated as 
follows. The large stem which forms the subject of the 
1 e.g. No. 1150 in the Williamson Collection. 
2 Williamson noticed the close resemblance in the wood of the two sections 
(1129 and 1130) to that of Nield’s specimen. In his catalogue he speaks of the 
wood and medullary rays of these two sections as practically proving the identity 
of Nield’s specimen and Lyginodendron Oldhamium. 
