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POPULAR SCIENCE REVIEW. 
The axis of the stem of Catamites (pi. xvi. fig. 13) was com- 
posed of cellular tissue, and this was surrounded by a solid 
cylinder of wood entirely composed of scalariform vessels, and 
without any trace of medullary rays. The vascular tissue was 
developed from a series of equidistant points near the circum- 
ference of the cellular tissue, and grew outwards and laterally 
until they united in a continuous cylinder fluted on the inner 
surface and with the flutings filled with the cellular tissue of 
the axis. A similar structure exists in the arborescent stems of 
some species of Cactus . There were constrictions at regular 
intervals in the woody cylinder, as in some recent Avtocarpece, 
The wood was covered by a thin epidermal layer of parenchyma, 
which is less seldom preserved than the cellular structure of the 
axis. 
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 capillary (Astero- 
phy llites ) linear-lanceolate ( Annularia , and Hippurites ) or 
cuneate ( Sphenophyllum ) and each whorl contained, in different 
species, from five to twenty leaves. 
The fruit was a strobilus (fig. 7) composed of whorls of 
scales alternating with and protecting whorls of peltate leaves, 
which supported the sporangia (fig. 4). The spores were simple 
and not compound as in Lepidostrobus. 
Various opinions have been entertained regarding the sys- 
tematic position of Catamites . It was originally supposed that 
they were huge Equisetacece , from the jointed and fluted stems. 
But these characters, which have been always described as 
external, are really on the interior of the woody cylinder. 
Catamites occur fossil either as cylinders of coal, the empty 
cellular core filled with sand, clay, or other foreign substance, 
or more frequently as flattened stems with more or less foreign 
matter in the interior, or more rarely preserved in calcareous 
or ironstone nodules and preserving to some extent the original 
structure. When the plants were destroyed the cellular axis 
speedily disappeared, and the woody cylinder alone formed the 
layer of coal. The cast of the interior, which in time became 
harder than the vascular tissues of the stem, acted upon as it was 
by the water that saturated the deposit, resisted more success- 
fully the pressure of the superincumbent deposits which in 
compressing the stem produced on its outer surface a counter- 
part of the furrows and constrictions of the internal cast. The 
outer surface of the stem was entirely free from these markings, 
so that the affinity to Equisetece derived from them is valueless. 
