Mesopeplum meringae (Tate, 1899)
TATE, R. 1899. A revision of the older Tertiary Mollusca of Australia. Part I. Transactions and Proceedings and Report of the Royal Society of South Australia, 23: 249-277 [p. 271]
1899 Pecten meringae Tate, 1899
Mesopeplum meringae (Tate, 1899); A. G. Beu & T. A. Darragh, 2001, Revision of southern Australian Cenozoic fossil Pectinidae, figures 60A-E.
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«MIOCENE.--Gippsland Lakes (V.).
Shell suborbicular in marginal outline, equilateral, inequivalve, radially ribbed, ribs in five groups, ears large. Right valve of about 50 mm. diameter, moderately inflated, ventral margin undulating corresponding with the areas occupied by the five groups of primary radial ribs and their intervening concave furrows. Primary ribs stout, flatly convex, with precipitous sides, about 1 8, variously grouped in twos, threes, and fives, forming elevated radial folds; the intervening concave areas with one or two slender ribs; the whole surface covered with close-set, slender, undulating, concentric lirae, more or less lamellose on the primary ribs (ten in a length of one mm. at the front on the medial line). Anterior ear large, falcate, with three or four radial riblets, crossed by concentric lirae forming slight squamae on the riblets and terminating in a serrated crest on the dorsal margin. Posterior ear of less size, right-angled triangular, ornamented with line concentric lirae. Left valve flat, the ornament similar to, but alternating with, that of the inflated valve; the anterior ear has, however, stouter riblets, and the transverse liraB rise into erect lamelliform scales. An adult left valve of 95 mm. diameter has five broad elevated rays, the ribs of which are finally evanescent, whilst the riblets in the interstitial furrows are not so pronounced as in the medium-sized valves. Dimensions of the figured shell.— Antero-posterior diameter, 40; ventro-dorsal diameter, 35; thickness through both valves, 10 mm. The name of the species perpetuates that of an aboriginal locality whence the fossils have chiefly been obtained. This species is separated from the bifrons-group by the absence of shagreen sculpture; the clustering of the ribs into sets allies it to polymorphoides among our fossil forms, and to undulatus and related species among living species of the Janira-group. It differs from polymorphoides, its nearest ally, by the regular convexity of the inflated valve, and by the distinct equilaterality of the shell.» RALPH TATE, 1899
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