Chlamys Röding, 1798
RÖDING, P. F. 1798. Museum Boltenianum sive Catalogus Cimeliorum e Tribus Regnis Naturae quae Olim Collegerat Joa. Fried. Bolten, M. D., p. d., Pars Secunda Continens Conchylia sive Testacea Univalvia, Bivalvia et Multivalvia. Typis Johan Christi Trapii, Hamburg, Germany, i-viii, 199 pp. [p. 161]
Chlamys (Chlamys) islandica (O.F. Müller, 1776); H. P. Wagner, 1991, Review of the European Pectinidae (Mollusca: Bivalvia), plate 4, figures. 1-3.
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«True Chlamys, as distinguished by Waller (1991) and in the present study, differs from both Praechlamys and Lyriochlamys in having a hinge plate and auricles composed entirely of foliated calcite (except for minor deposits of aragonite in ligament insertion areas). On the inner surface of the disk, aragonite rarely extends more than a very short distance beyond the pallial line and is usually entirely confined to an area inside the pallial line. In boreal species, such as Chlamys islandica (Miiller, 1776) living in the North Atlantic, a calcitic inner layer transgresses the aragonitic ostracum from the dorsum ventralward inside the pallial line early in ontogeny (Waller, 1991). The range of radial sculpture of Chlamys broadly ovarlaps that of Lyriochlamys. Branching ribs commonly occur on the right valve and intercalated ribs on the left, but branching may be absent altogether or intercalation may sometimes occur on both valves without branching. Antimarginal microsculpture is present but is commonly masked on the disk flanks by radial costation.
Defined in this way, true Chlamys is a Cenozoic genus, and Maastrichtian Lyriochlamys cretosa, which shows a Chlamys-like microstructure in the northern part of its range, may well be the species from which Chlamys originated. Although pectinid history in the Paleocene is still very obscure, true Chlamys was already well represented in the middle Eocene of Europe (Waller, 1991) and is well represented in the later Cenozoic and in the modern ocean.» WALLER, T. R. & L. MARINCOVICH JR. 1992. New species of Camptochlamys and Chlamys (Mollusca: Bivalvia: Pectinidae) from near the Cretaceous/Tertiary boundary at Ocean Point, North Slope, Alaska. Journal of Paleontology, 66 (2): 215-227, figs. 1-5. [p. 224]
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