544 MR ROBERT KIDSTON ON 
At lt., fig. 5, Pl. IIL, is seen the opening through which the leaf trace has 
passed to the leaf. The leaf cushions are attached to a continuous zone of under- 
lying periderm (Pl. III. fig. 19, pd.), formed of very dense elongated fibres of small 
diameter, with fairly thick walls. In longitudinal section this tissue is usually very 
opaque, and seldom shows its structure distinctly. In transverse section (Pl. UI. 
fic. 21) the fibres are seen to be arranged in close radial rows. 
If a transverse section of cortex with several attached leaf bases be examined, 
it will be seen that some of the leaf bases have only a narrow band of dark dense 
tissue, as at Pl. I. fig. 3, l.c., whereas others seem to be entirely composed of it, 
as at fig. 3 lc.’ This is explained by reference to fig. 5 and fig. 19, Pl. ILL 
the section passes through the lower part of the cushion the greater part of the 
section will show transparent parenchyma, whereas if the section passes through 
the upper part of the cushion it will be composed of dense opaque tissue. 
A leaf cushion in transverse section is given on Pl. III. fig. 20, The dark 
broken-down margin is reduced here in thickness (p.p.), while the more transparent 
parenchyma occupies at this position the greater width of the cushion. At pd. 
are seen some fragments of the periderm. 
The cause of the flexuous striations on the surface of the stem (Pl. I. fig. 2) 
where the leaf cushions have been removed is not very clear, but they seem to 
be formed at the point of union of cortex and periderm, and are probably caused 
by the projecting teeth of the latter (see Pl. III. fig. 20, pd.). 
A section of a cushion approximately parallel with and a short distance below 
the outer surface is given on Pl. III. fig. 22. The two parichnos (par.) are seen, 
but the delicate tissue with which they were filled has mostly decayed. The leaf 
trace lying between them is too imperfectly preserved to admit of a detailed description. 
The parenchyma of the groundmass is here well preserved (Pl. IL. fig. 24). 
Cone Scars.—On the specimen showing the outer surface of the bark given on 
Pl. I. fig. 18 part of a verticil of cone scars is seen at c.s. 
In one of the tangential sections of the cortex of the specimen shown on Pl. L 
fig. 1 two vascular strands belonging to cones are cut through. This specimen is 
shown enlarged eight times at fig. 23, Pl. III, where the branches going to the cones 
are lettered c.s. and c.s.’ 
The cone axis ¢.s.’, fig. 28, Pl. III., is seen enlarged on PI. III. fig. 25. | 
The peripheral zone of cortex, b, which has accidentally separated off from the rest, — 
is too much disorganised to show the structure, but probably corresponds to the 
periderm. ‘The space lettered d is a mechanically produced rupture. 
The rest of the cortex consists of fairly thick-walled and apparently parenchymatous 
cells, which increase in diameter as they are traced inwards (PI. III. fig. 26). This 
tissue, which undoubtedly belongs to the cortex, is separated from the solid axis of the 
cone by a clear empty zone (Pl. III. fig. 25, g, and Pl. I. fig. 27, g), which was 
probably occupied by some delicate tissue. 
