Spondylus gaderopoides McCoy, 1876
MCCOY, F. 1876. Geological Survey of Victoria: Prodromus of the palaeontology of Victoria; or, figures and descriptions of Victorian organic remains. Government Printer, Melbourne. Decade 4, 32 p., pls. 31-40. [p. 27, pl. 38, figs. 1, 1a-1d]
1876 Spondylus gaderopoides McCoy, 1876
F. McCoy, 1876, plate 38.
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«[Genus SPONDYLUS (Lin.). (Sub-kingd. Mollusca. Class Lamellibranchiata. Order Pleuroconcha. Fam. Spondylidae.)
Gen. Char.— Shell irregular, inequivalve, inequilateral; hinge-line short, straight, forming quadrate ears on each side of the beaks; a flat triangular cardinal area divided longitudinally by a median cartilage groove which separates the beak of the large attached valve from the hinge-line; 2 large cardinal teeth in each valve with pits for opposite teeth, and a triangular central cartilage pit connected with groove of cardinal area; ligament simple, external; adductor impressions large, rounded a little on the posterior side of middle; pallial scar, strong, entire; surface rough spiny. Mesozoic to recent warm seas in deep water attached to corals or rocks.] DESCRIPTION.— Obliquely ovato-trigonal, gibbous, surface radiated with very irregular close small ridges of very unequal sizes, often in groups of five with middle one largest, occasionally alternate, roughened, with close spinose transverse scales, usually one to five very small between each pair of larger striae, from ½ to 1 line in width; from 4 to 10 thick ridges set with moderately close variable long arched spines, depressed near base, often compressed beyond, generally fewer on the upper than on the lower valve, but sometimes the lower valve with no spinose ridges in the middle portion, but two or three on each side; the large valve often with prominent concentric scale-like laminae near the beak and on the sides; average length of large valve from beak to front margin, 5 inches ; proportional length from hinge-line (and length of smaller valve), 77/100; greatest width, 75/100; depth of larger valve, 27/100; depth of small valve very variable.
This fine species of Spondylus varies greatly in the convexity of the upper valve, and in the number of the thick spinose ridges on each valve; these are from 1 to 3 lines in width, and set with large depressed spines more closely placed towards the margin. It is quite unlike any shell living in the Victorian waters, and differs from the recent and Tertiary S. gaderopus in the much fewer, thicker, and stronger spinose ridges, and the much more numerous unequal and more closely spinulose intervening striae. At first glance it approaches more nearly to the living Spondylus Sinensis and S. imperialis, but differs in its much more numerous intermediate striae, and their much more numerous regular close smaller spinulose scales. It approaches slightly nearer to the radiation of the recent S. Ducalis, from which it differs in all other respects.
The S. bifrons of Munster from the Osnabrück beds is the nearest analogue amongst fossil species, but ours is much larger, with fewer spinose ridges on the attached valve, and having them quite as numerous on the upper valve as on the attached one, or even more so; the ridges with large spines are also much more prominent in the Victorian species. Occurs in great abundance in Miocene Tertiary sandy strata of Bird Rock Bluff (Aᵈ 23) near Geelong. More rare in the cream-colored Miocene limestone of Boggy Creek, six miles from Sale, Gippsland. EXPLANATION OF FIGURES
Plate XXXVIII.— Fig. 1, right or attached valve, natural size, inner view, showing muscular impressions and pallial scar, large cardinal area with its median grove extending to the internal triangular cartilage pit, flanked on each side by a large cardinal tooth, each of which on its outer side has the deep pit for the teeth of the opposite valve. Fig. 1a, external surface of same specimen, natural size, showing the usual concentric lamellar character near the beak and on the sides. This individual shows a rather greater number of the large spinose ridges than usual. Fig, 1b, portion of large ridge and adjacent smaller ones from the side near the beak, magnified. Fig. 1c, small intermediate ridging near the middle margin, magnified. Fig. 1d, side view of same specimen, natural size.
N.B.— All the figures on this plate have been unfortunately reversed in the lithographing.» FREDERICK MCCOY, 1876
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