' 9 ^ M. C. St opes on the Leaf-structure of Cordaites. 
This type of bundle is also found at the edges % of the leaves of 
Poroxylon 1 which are described as jacking the centrifugal wood 
of the main bundles. The modern Cycads on the other hand shew 
a parallel to the more complicated type of the Cordaiteae in which, 
as in C. lingulatus, the centrifugal xylem is well developed. 
I am much indebted to Professor F. W. Oliver for the use of the 
fossil slides, and for the interest he has shewn in their description. 
The sections figured are all in the collection belonging to the 
Botanical Department of University College. 
1 Bertrand and Renault, Reclier. sur les Poroxylons, p. 354. 
EXPLANATION OF PHOTOGRAPHS AND FIGURES ON PLATE IX 
ILLUSTRATING MISS M. STORES’ PAPER ON “THE LEAF 
STRUCTURE OF CORDAITES. 
Photograph 1.—Trans, sect, of the leaf of Cordaites lingulatus ( x 130.) 
px. protoxylem 
x 1 . centripetal xylem. 
x 2 . centrifugal xylem. 
p. phloem. 
Photograph 2.—(et seq). C. principalis. Trans, sect, of leaf ( x 75.) 
v. vascular bundle. 
5. large sclerotic strand on the lower side. 
For details see photos. 3 and 4. 
Photograph 3.—Single bundle enlarged (X200). The one nearest the 
broken end of leaf, phot. 2. 
px. protoxylem. 
x 1 . centripetal xylem. 
p. xylem parenchyma. 
ph. phloem. 
55. inner pitted sheath (“ primitive transfusion-tissue ”). 
5. outer pitted sheath <“ peridesmic transfusion-tissue ”). 
f. crushed phloem cells, which appear somewhat like xylem as 
they are out of focus. 
Photograph 4.—Bundle about to divide (X200). 
From another bundle of the leaf partly shewn in phot. 2. The 
inner sheath is beginning to grow in, separating the two groups 
of phloem. 
Figure 5.—Diagram of trans. sect, of a single bundle and adjacent 
tissues (x 180.) 
Lettering as phot. 3. 
Figure 6.—Diagram of long. sect, of bundle (X300.) 
Lettering as above. 
si. sheath cells adjacent to and above centripetal xylem 
(? pitted.) 
Figure 7 — Parenchyma of leaf ( x 130), section cut parallel to midrib 
and at right angles to plane of leaf, somewhat oblique. 
sc. sclerenchymu of large strand on the lower side. 
5. spongy tissue. 
p. palisade tissue. 
