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When reduced to thin, transparent plates, these latter show us the organization of the wood of Arthropitus, Cordaites, and Calamodendron, and of the petioles of Aulacopteris, that is to say, of the ligneous and arborescent plants that we most usually meet with in the coal measures of Commentry in the state of impression or of coal.
The corky nature of this region of the bark was likely richer in carbonizable elements than the wood properly so called, and had, in consequence, to undergo much less shrinkage. Dr. Commentry cannel coal, X200. Etienne; transverse section, X200. Calamodendron, Commentry; prosenchymatous portion of the wood carbonized, X200.
The foliage consisted of whorls of long narrow leaves, which differed only from the fern asterophyllites in the fact that they were single-nerved. Sir William Dawson assigns the calamites to four sub-types: calamite proper, calamopitus, calamodendron, and eucalamodendron. Root of Catamites Suckowii. Calamocladus grandis.
If the two fragments of the same wood are, one of them silicified and the other simply carbonized and preserved in sandstone, the diminution in volume will have occurred in all directions in the latter of the two. Figs. 9 and 11, which represent a portion of the fibrous region of Calamodendron wood, may give an idea of the shrinkage that has taken place therein.
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