. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. 472 CALAMITES. [Ch. XXIV for, like the common "horsetail," they usually exhibit little more than hollow jointed stems, furrowed externally. (See figs. 522, 523, 524.) Mr. Salter stated to me many years ago his conviction that the calamite as frequently represented by palaeontologists was in an in- verted position, and that the conical part given as the top of the stem was in truth the root. This point Dr. Dawson and I had opportuni- ties of testing in Nova
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. 472 CALAMITES. [Ch. XXIV for, like the common "horsetail," they usually exhibit little more than hollow jointed stems, furrowed externally. (See figs. 522, 523, 524.) Mr. Salter stated to me many years ago his conviction that the calamite as frequently represented by palaeontologists was in an in- verted position, and that the conical part given as the top of the stem was in truth the root. This point Dr. Dawson and I had opportuni- ties of testing in Nova Scotia, in 1853, where we saw many erect calamites, having their radical termination as in the foregoing figure (fig. 524). The scars, from which whorls of vessels have proceeded, are observed at the upper, not the lower, end of each joint or inter- node.* The specimen (fig. 522), therefore, is no doubt the lower end of the plant, and I have therefore reversed its position as given in the Avork of Lindley and Hutton. M. Adolphe Brongniart, following up the discoveries of Germar and Corda, has shown in his "Genres de Vegetaux Fossiles," 1849, that many Calamites cannot belong to the Uquiseta, nor probably to any tribe of flowerless plants. He conceives that they are more nearly allied to the Gymnospermous Dicotyledons. They possessed a central pith, surrounded by a ligneous cylinder, which was divided by regular medullary rays. This cylinder was surrounded in turn by a thick bark. Of fossil stems having this structure Brongniart formed his genus Calamodendron, which includes many species re- ferred by Cotta, Petzholdt, and TJnger to the genus Calamitea. The Calamodendron is described as smooth externally, its pith being articulated and marked with deep external vertical striae, agreeing, in short, with what geologists commonly call a Calamite. Since the appear- ance of Brongniart's essay, Mr. E. "W. Binney has made many important discoveries on the same subject; a
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1868
