. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Cn. XXIV.] ASTEROPHYLLITES. 473 an internal pith answering in character to the Calamodendron, and yet having outside of it another jointed cylinder vertically grooved on its outer surface, so that in the same stem we have one calamite enveloping another. Yet that they both formed part of the same plant is proved by the following circumstances:—1st. Near each articulation of the pith radiating spokes are seen to proceed and penetrate the ligneous zone. One complete wh
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Cn. XXIV.] ASTEROPHYLLITES. 473 an internal pith answering in character to the Calamodendron, and yet having outside of it another jointed cylinder vertically grooved on its outer surface, so that in the same stem we have one calamite enveloping another. Yet that they both formed part of the same plant is proved by the following circumstances:—1st. Near each articulation of the pith radiating spokes are seen to proceed and penetrate the ligneous zone. One complete whorl or circle of these radii is visible in the foregoing fiorire near the bottom of the hollow cavity, whilst another and superior whorl is incomplete; several radii, corresponding to the first, remaining, while the rest have been broken away, their place being shown by scars which they have left. 2dry. In addition to these whorls, called medullary by Professor William- son, there are seen in other specimens a set of true or ordinary me- dullary rays. 3dly. The woody zone, penetrated both by the spoke- like vessels before mentioned and by the medullary rays, is usually reduced to brown carbonaceous matter, preserving merely a tendency to break in longitudinal slips, but in some specimens its fibrous tissue is retained, and resembles that of Dadoxylon. 4thly. Outside of this zone again is another cylinder, supposed to have been originally a thick cellular bark, nearly equal to one-third of the whole stem in diameter, grooved and jointed externally like the pith. In conclusion, I may remark that these discoveries make it more and more doubtful to what family the greater number of Calamites should be referred. Their internal organization, says Professor Williamson, was very peculiar; for while they exhibit remarkable affinities with gymnospermous dicotyledons, the arrangement of their tissues differs widely from that of all known forms of gymnosperms. Asterophyllites.—The grac
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