Notes. 
239 
Medullary rays uniseriate, 1-12 cells in height. 
Dictyoxylon zone of cortex narrow ; periderm very broad. 
Roof-nodule, Shore, Littleborough. 
This is a very distinct form, characterized by the very early fusion of the two 
leaf-trace strands, and the definite sheath about the primary xylem. 
Three specimens have been observed (possibly fragments of one), all being 
about 5 cm. in diameter, with a pith about 2 cm. across. 
The species is named after Mr. James Lomax. 
5. Mesoxylon platypodium , sp. nov. 
Leaf-bases very broad, scattered. 
Pith large, with a persistent outer zone; interior not preserved. 
Twin-bundles of each leaf-trace very far apart at margin of pith; where they 
leave the wood each of these bundles already subdivided, as regards its primary 
xylem. Leaf-trace in cortex consisting of two distinct rows of four bundles each. 
Two distinct axillary steles to the same leaf. 
Centripetal xylem very well developed and persistent at margin of pith. 
Scalariform tracheides apparently limited to leaf-traces or their neighbourhood; 
those of secondary xylem sometimes pitted throughout. 
Medullary rays 1-12 cells in height. 
Sparganum zone of cortex narrow. 
Roof-nodule, Shore, Littleborough. 
This is the most isolated of the five species, and is characterized by the extreme 
separation (2 mm.) of the twin-bundles of the trace, and by their secondary division 
while still in the woody zone. 
The two axillary steles corresponding to a single leaf constitute a very striking 
feature. It is interesting to note, in this connexion, that the axillary stele in M. Sutcliffii 
is sometimes double, though the two steles appear always to reunite before entering 
the bud. The specific nam z, platypodium, refers to the great breadth of the leaf-base. 
The systematic position of the genus Mesoxylon will be discussed in our full 
paper which is in course of preparation. In the meantime it may be pointed out 
that these stems appear to completely bridge the gap, so far as anatomy is concerned, 
between the Poroxyleae and the Cordaiteae, and thus form valuable links in the chain 
of forms connecting the Pteridosperms with the typical Gymnosperms. 
All the specimens were discovered by Mr. James Lomax and his son, in the 
Shore material, and the sections cut by them. 
D. H. SCOTT. 
A. J. MASLEN. 
