ON LEPIDODENDRON AND CALAMITES. 347 
Thiiringer Waldes’ (Vienna, 1856), have restored the stem of a Cala- 
mites with a thick epidermal cellular layer, and this they have furrowed 
on its outer surface; but as this layer was so perishable that it has 
almost invariably disappeared, it could not have produced the furrows 
which occur in almost every specimen. When the stems were thrown 
down, the cellular portions were generally completely decayed, and the 
space occupied by the axis was filled with the clay or sand in which 
the plant finally rested. In this way a cast of the interior was made, 
which in time became harder than the vascular tissue of the stem, and 
the pressure of the superincumbent deposits flattened and compressed 
the woody cylinder, producing on its upper surface a counterpart of the 
internal cast, with its furrows and constrictions. The furrows vary in 
size and closeness in different specimens, and produce indications suf- 
ficient to account for the different species that have been established. 
The stem somewhat rapidly contracted at the base, the nodes 
shortening and giving off long cylindrical roots which spread laterally 
through the soil. 
The main stem was simple, but at intervals gave off whorls of 
slender branches, and these again bore branches or leaves also arranged 
in whorls. The leaves were linear-acuminate, and each whorl contained 
from ten to twenty leaves. 
The fruit (t. 56, f. 7) was composed of whorls of scales alternat- 
ing with, and protecting whorls of sporangium-bearing spines (t. 56, 
f. 9). It was borne either at the termination of the primary branches 
or in whorls around them, and was composed of a shortened axis, with 
the leaves specially developed. The strobilus described by Ludwig 
(Meyer’s ‘ Paleeontographica,’ vol. x. p. 11, t. 2), consists of from 
twenty to twenty-five series of barren protecting scales, arranged fifteen 
in a whorl, the scales of each whorl being opposite to those in the 
others. Between the scales is a whorl of five short spines, each sup- 
porting four flask-shaped sporangia. The spines of one series are 
arranged opposite to the spines of the other, that is to say, they are 
arranged perpendicularly on the axis, the one directly over the other. 
I have confirmed these observations on specimens of the fruits found 
in Britain, belonging to Dr. Hooker, and made some important addi- 
tional observations on the structure of the strobilus and the contents 
of the sporangia, which I hope soon to publish. 
It is not easy to find anything analogous to Calamites among recent 
