Spondylus pseudoradula McCoy, 1877
MCCOY, F. 1877. Geological Survey of Victoria: Prodromus of the palaeontology of Victoria; or, figures and descriptions of Victorian organic remains. Government Printer, Melbourne. Decade 5, 41 p., pls. 41-50. [p. 17, pl. 45, fig. 2]
1877 Spondylus pseudoradula McCoy, 1877
F. McCoy, 1876, plate 45.
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«DESCRIPTION. — Longitudinally ovate, apical angle about 85° lightly oblique, both valves moderately convex, substance very thin; ears rather small, covered with radiating very numerous, fine, closely spinulose striae; surface of upper valve with about ten to fifteen narrow prominent ridges radiating from the beak, set at irregular intervals with long curved, compressed, rather slender spines; between each pair of larger ridges are three, five, seven or thirteen very much finer alternate striae, the middle one largest, all closely set with fine setaceous spines. The lower valve with more numerous spinose ridges (about twenty). Length of large specimens, 31 inches; more usual size, about 1½ inches; proportional width, 90/100 to 80/100; length of hinge-line, 50/100 to 40/100; depth of upper valve, 25/100 to 30/100; depth of Iower vaIve, 30/100 to 50/1000; nine fine ridges in a space of 2 lines at 10 lines from beak.
This thin, delicate species is easily distinguished from the other large common species, S. gaederopoides (McCoy), of the same beds by the spinulose small ridges between the larger ones. There is no recent species very nearly allied to it; the S. multimuricata of the Moluccas coming perhaps nearest, but having more numerous ridges with thicker and coarser spines, and much fewer and less spinulose intermediate striae. Of fossil species, the nearest is the S. rarispina (Desh.) and the S. radula (Desh.) of the older French Tertiaries, from which it differs in its narrower form, fewer large ribs, and more numerous and more spinulose interstitial ones. The concentric scaly laminae so common on the rostral portions of the lower valve of this genus are scarcely indicated, and only on the sides, if at all. The species is in most localities only about 1½ inches in length, but at Bairnsdale Mr. Howitt has collected gigantic specimens, upwards of 3 inches in length, which agree with the others in all the main characters, and in these the unusual thinness of the valves is even more remarkable than in the small ones, recalling the living Australian Spondylus fragilis of Sowerby in this respect (although quite different in all other characters). Some of these Bairnsdale specimens show the spines nearly 1½ inches in length, tapering to the end and with the remarkable lateral compression contrasting with the flattening in the opposite direction more common in other species.
Not uncommon, of small size, in the Oligocene Tertiary clays and limestones near Mount Martha, in Port Phillip Bay; rare, of small size, in the clay bed of Muddy Creek; about the same size in the sanely Tertiary (Aᵈ 28) of Fyansford. Very large in the sands and limestones of Miocene Tertiary age of Bairnsdale. Of large size, very thin and fragile, in the Older Pliocene sandy clays of Mordialloc. EXPLANATION OF FIGURES
PLATE XLV.— Fig. 2, upper valve of middle sized specimen, natural size. Fig. 2a, view of hinge of same specimen. Fig. 2b, profile outline view of same specimen. Fig. 2c, portion of surface magnified to show the spinulose character of the smaller ridges between the larger ones.»
FREDERICK MCCOY, 1876
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