Amussiopecten africanus (Cox, 1927)
COX, L. R. 1927. Neogene and Quaternary Mollusca from the Zanzibar Protectorate. In Anonymous (Eds.): Report on the Palaeontology of the Zanzibar Protectorate based mainly on the collection made by G. M. Stockley: 13-102, pls. 3-19. Published by Authority of the Government of Zanzibar. [p. 40, pl. 6, figs. 3, 4]
1927 Pecten (Amussiopecten) africanus Cox, 1927
L. R. Cox, 1927, plate 6.
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«Specific characters:— Shell slightly inequivalve. Right valve convex in profile, ornamented. with radiating coste, about 22 in number near the umbo, but with the 3-4 lateral ones on each side soon becoming obsolete; costae wide, flattened, depressed, separated by slightly narrower interspaces. Left valve less convex than the right, ornamented near the umbo with about 20 costae, of which 3-4 lateral ones on each side soon become obsolete; coste at first acute, subsequently widening and becoming depressed-rounded, although separated by interspaces of greater width. Costae and interspaces crossed by fine concentric threads. Ears fairly large, sub-equal, the right anterior with a slight sinus below it. Interior of both valves with a number of narrow, salient costa grouped in pairs (owing to the condition of the specimens their number cannot be counted).
Localities:— Pemba 48, 94. Material:— The holotype (L. 43796), a bivalve specimen from Loc. 94, and one paratype (L. 43797), a left valve. Dimensions:— (Holotype) diameter ca.42mm., inflation 12mm. The paratype, the margins of which are broken, is larger (diameter ca. 70mm.). Comparison with other species:— From P. (A.) gregoryi this species differs in the smaller number of its principal costa and in its stronger inflation, particularly apparent in the much more convex profi.le of its right valve. Although on the right valve the number of ribs counted near the umbo is not very much smaller than in P. gregoryi, in the present form the lateral coste soon become obsolete, so that the number of ribs is reduced to about 15, which are fairly regularly spaced. In P. gregoryi the corresponding number is about 21, and these are crowded towards the central region of the shell, leaving smooth areas adjoining the dorsal margins of the disc. Nevertheless, P. africanus has a greater number of costa than P. burdigalensis or any other Mediterranean form, and is readily distinguished both by this feature and by the profiles of its two valves.» LESLIE REGINALD COX, 1927
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