ioi6 
Scott . — The S true here of 
ray-cell ; they are less regular in form than elsewhere, and seem to be 
unbordered, though the preservation leaves this uncertain. 
In the outer secondary wood the position of a double leaf-trace is 
marked, in tangential section, by the presence of two knots of irregularly 
interwoven tracheides, enclosing in their meshes the tracheides of the 
outgoing strand. 
The Phloem and Pericycle. 
The phloem-zone is traversed by long, sac-like elements, possibly of 
a secretory nature. In one of the specimens especially (slide 2325), they 
are very conspicuous ; they are from 100 to 200 ju, in diameter ; their thick 
walls appear black and their contents brown (PI. LXXXVII, Figs. 1 and 6). 
These elements extend into the pericycle, which may be distinguished 
from the phloem in longitudinal section by the fact that only short cells 
are present between the sacs. 
In the phloem proper, which is imperfectly preserved, there are long 
tubes, about 40 /x in diameter, which in tangential section are seen to form 
a kind of mesh-work, enclosing the phloem-rays (LXXXIX, Fig. 20). 
Transverse or oblique walls appear to occur at long intervals. These 
tubular elements may probably be the sieve-tubes. 
The Cortex. 
The inner cortex is remarkable for the great development of secondary 
tissue, resembling periderm (PI. LXXXVII, Figs. 2 and 6). The whole of 
the thin-walled zone has its cells radially arranged ; the radial cell-rows, how- 
ever, are not continuous throughout ; the tangential divisions appear to have 
gone on in more than one layer, and not to have been limited to a definite 
phellogen. The zone in question, which reaches a thickness of at least 
5 mm., may perhaps be more properly called secondary cortex rather than 
periderm. 
In the hypodermal zone the radial sclerotic bands are usually narrow, 
and vary much in depth. There is no extensive tangential section of this 
zone, but some cases of anastomosis between the bands have been observed. 
Hence we may speak of the mechanical hypoderm as of the Dictyoxylon 
type. Towards the exterior the sclerotic bands unite in a continuous zone 
of moderately thick-walled tissue. The outer tissues are very imperfectly 
preserved, but the contour, as far as shown, appears to prove that the leaf- 
bases were scattered, and not crowded as in M. Sutcliffii. 
Diagnosis. 
An amended diagnosis of the species may now be given : 
Mesoxylon Lomaxii , Scott and Maslen, 1910. 
Leaf-bases scattered. 
