Abstract
LONDON. Geological Society, June 4.—Mr. G. W. Lamplugh, president, in the chair.—Dr. A. S. Woodward; The dentition of the Petalodont shark, Climaxodus. The author describes the nearly complete dentition of a new species of Climaxodus from the Calciferous Sandstone of Calderside, near East Kilbride (Lanarkshire), now in the Royal Scottish Museum, Edinburgh. Climaxodus and Janassa are shown to be two distinct genera. These Petalodonts are especially noteworthy among the Elasmobranchii, because during the greater part of the life of each individual there cannot have been more than six or eight teeth in succession, a condition remarkably different from that in all ordinary sharks and skates, in which the suc-cessional teeth are always very numerous and rapidly replaced. The same limited tooth-succession is to be observed in the Carboniferous Cochliodontidae, and perhaps also in the contemporaneous Psammodontidas.—F. Debenham: A new theory of transportation by ice: the raised marine muds of South Victoria Land (Antarctica). A series of deposits of marine muds are found on the surface of floating “land-ice” in the deep bays of Ross Sea (Antarctica). Similar deposits are also found on land up to a height of 200 ft., in some cases on old ice, in other cases on moraine. The deposits are briefly described, and former theories concerning them are discussed. A new theory is put forward, prefaced by an account of the nature of the typical ice-sheet which bears them. The upper surface of the sheet is known to suffer a net annual decrease, and evidence is given to show that the lower surface has a net increase by freezing from below. The theory is that the sheet will freeze to the bottom in severe seasons, and enclose portions- of the sea-floor. Owing to the method of growth of the sheet bv increments from below, the enclosed portions will ultimately appear on the surface, thus being raised vertically as well as translated horizontally.
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Societies and Academies . Nature 103, 319–320 (1919). https://doi.org/10.1038/103319a0
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DOI: https://doi.org/10.1038/103319a0