OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
503 
Fig. 13 is a fine longitudinal section of this strobilus from Halifax, for which I am 
indebted to Mr. Binns. The vascular axis is seen at a, composed of barred vessels at 
its inner portion, but at each of the three prominent angles of this bundle there is a 
cluster of smaller spiral vessels. These clusters mark the points from which, as I 
shall show directly, the vascular bundles are given off to the bracts. The cortical 
portion, b, the sterile bracts, c, and the fertile ones, d, have already been described ; 
but the section well illustrates the oblong cells which constitute the uppermost layer 
of each sterile bract as distinguished from the coarser parenchyma of its inferior 
portion. The sporangia, some few of which contain spores, appear at e ; but that 
which is of the most importance to my present purpose is the existence of some 
symmetrically-disposed apertures, cl', d", in the bark, through which apertures the 
vascular bundles of the bracts have originally passed—Those marked cl' going to the 
fertile bracts and consequently being six in number in each verticil, whilst those 
indicated by d" have been double that number, and destined for the corresponding 
number of sterile bracts. Fig. 14 is a beautiful transverse section through the sterile 
bractigerous disk, enlarged 17 diameters. At a is the vascular axis; at b the outer 
cortical parenchyma, the inner layer being almost entirely wanting; at c, c we have 
the tissues forming the bractigerous disk, chiefly composed of coarse cellular paren¬ 
chyma, but at c we find the cells elongated radially,"' going to the free vertical bracts 
already described by Mr. Binney, Mr. Carruti-iers, and myself. Running along the 
centre of these lines of prosenchymatous cells I find in each of two or three of the 
bracts the bundle of small spiral vessels pursuing its way across the disk to reach the 
free marginal bract. At f f we have transverse sections of the vertical portions of 
the bracts belonging to the next inferior verticil, whilst the extreme tips of those of 
the next lower verticil but one appear at eg, g. 
Fig. 15 is a transverse section of the Calamostachys made through the plane of the 
fertile sporangiophores. It is the only specimen I have yet seen in which the cortical 
structures are preserved in their entirety. The central vascular axis, a, is closely 
surrounded by a dense cellular layer, b ; this passes into a- more open and delicate 
cellular tissue, b', in which there are large lacunae—but which latter are probably due 
to partial desiccation, since they are irregularly distributed. Bounding this externally 
is the outermost cortical layer preserved in all specimens of this fruit, and of which the 
sporangiophores, cl, are mainly prolongations. At cl' we have part of the peripheral 
peltate expansion of the sporangiophore, cl. 
But the points of this section which are specially important relate to the central 
vascular axis with its dense cellular investment; the form of its transverse section is 
here unmistakably that of a triangle with each of the angles truncated at its extre¬ 
mity. We further see at each of two of these truncated angles two small vacant 
spaces, which, like the similar spaces, cl', cl", in the outer bark of fig. 13, doubtless 
* These lines of elongated prosenchymatous cells only occupy the upper surface of the disk until they 
reach the upper extremities of the free bracts, f, g, which portions are chiefly composed of such cells. 
3 T 2 
