226 
Lycopodiaoese of Coal-measures. 
r Monthly Microscopical 
L Journal, Nov. 1, 1869. 
layer of elongated cells corresponding to that in Lejpidodendron 
selaginoides, marked e in Figs. 1 and 2 of Plate XXYII. 
The specimens of TJlodendron are most frequently casts in sand- 
stone of the outer surface of the stem, or amorphous casts of the 
interior formed in the cavity left in the rock after the more or less 
complete decay of the original organism. Impressions of the scars 
are occasionally seen on the surface of the laminae in bituminous 
shales. 
The specimen figured on Plate XXXI. is in the collection of 
the late Kohert Brown, now in the Botanical Department of the 
British Museum. It has the label, " Coal Measures — Hemsford or 
Bradford — Eev. K. B. Cook, F.G.S., Doncaster." It is a fragment 
measuring 1^ inches in length, 5 inches in breadth, and IJ inch 
in thickness. The surface is covered with the carbonized remains 
of the scale-like leaves arranged in a quincuncial manner. It is very 
much flattened, and exhibits three round conical pits characteristic 
of the species on each of its two edges. About two-thirds of the 
transverse section is shown at Fig. 1 of the natural size. The 
greater portion of the interior is composed of amorphous shale, but 
the tissues of the centre are more or less perfectly preserved. This 
forms a well-defined cylinder Aths of an inch thick in diameter. 
It corresponds to the axis and surrounding cylinder of vascular 
tissue in Lepidodendron selaginoides, Sternb. (Plate XXYII., 
Figs. 1 and 2, a and h), and consists of similar tissues. 
The transverse section (Fig. 1) shows that the inner portion is 
somewhat decayed; the cavities have been filled in with white 
crystallized corbonate of lime. Sufficient of the original tissue, how- 
ever, remains to show clearly what it was. In the enlarged portion 
(Fig. 2 a) it is seen to be composed of vessels of different sizes, 
and of a circular or polyhedral form in transverse section. They 
do not appear to be arranged as I have described them in Lepido- 
dendron selaginoides. The larger vessels are found in the interior, 
and amongst them a number of smaller vessels are irregularly inter- 
mixed. Towards the circumference the vessels are uniformly 
smaller, but they do not alter their form, being as nearly circular 
as those of the interior. In longitudinal section (Fig. 3 a) they 
are seen to be scalariform vessels. Their apparent shortness in the 
drawing arises from the direction of the section exhibiting a some- 
what oblique cut through the vessel, and not from their actual 
terminations being seen. 
The axis is surrounded by a cylinder of radiating scalariform 
tissue (Figs. 2 and Sh). At its inner margin the diameter of the 
vessels composing it are small — their size increases outwards. I 
have not been able to detect any structure in this cylinder besides 
the scalariform vessels. The radiating lines are frequently separated 
by portions of calcite containing no organic structure. None of 
