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Genus Megathiris d'Orbigny, 1847 |
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Megathiris d'Orbigny, 1847, p. 269, nom. nov. pro Argiope Deslongchamps, 1842, p. ix, non Audouin in Savigny, 1827 [*Anomia detruncata Gmelin, 1791, p. 3,347; OD] [=Megathyris Bronn, 1848, p. 244, nom. van.; Argyope Davidson, 1850, p. 65, obj., non Savigny, 1826]. [Type-species = Anomia detruncata Gmelin, 1791 p. 3347] Small, broadly transverse, hinge line straight; ventribiconvex, multiplicate, anterior commissure rectimarginate to slightly uniplicate; beak short, attrite; foramen hypothyrid, deltidial plates disjunct. Hinge teeth small, elongate; pedicle collar supported by long, narrow median septum and 2 subdued lateral septa extending almost to anterior margin. Cardinal process small, transverse, grooved; cardinalia with low hinge platform uniting 2 prominent socket ridges; crura short, widely separated, crural processes prominent, horizontal, pointed; median septum very long, narrow, high; flanked in anterior part of shell by 2 lateral septa reaching to near middle of dorsal valve; loop of 2 slender, arcuate descending branches free only near crura, attached to base of crura, valve floor, and anterior extremities of lateral septa and median septum; lophophore attached to dorsal mantle, ptycholophous; rarely weakly spiculate. Upper Cretaceous (Campanian) - Present
Diagnosis from volume 5 of the Treatise on Invertebrate Paleontology (2007) |
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Megathiris detruncata: in cave, 12 m depth - Madeira. Copyright © Peter Wirtz
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