Pecten antiaustralis Tate, 1886
TATE, R. 1886. The lamellibranchs of Older Tertiary of Australia (part 1). Transactions and Proceedings and Report of the Royal Society of South Australia, 8: 96-158, pls. 2-12. [p. 106, pl. 9, figs. 7a-c]
«Pecten antiaustralis, spec. nov. PI. ix., figs. 7a—7c.
Synonym.— P. asperrimus, var. Tate. Trans. Rov. Soc, S. Aust., vol. iv., p. 34, 1882.
Shell sub-orbicular, moderately convex sub-equivalve, the right valve less convex, sub-equilateral, rayed with about 25 ribs which are flanked by one or two smaller ribs on each; the ribs and riblets are convex, crossed by erect lamellae, the interstitial furrows flattish, arcuately striated. Ears unequal large, radially ridged and transversely lamellate-scaly; right-posterior, triangular, obliquely truncated, anterior produced, sinuated ventrally; left-posterior similar to corresponding one in right valve, anterior larger, obtuse angled. Dimensions of a large individual.— Length and height, 58; thickness through both valves, 25 millimetres. Localities. — Oyster beds in the uppermost strata at Adelaide, Hallett's Cove, and Aldinga Bay; Edithburg and Stansbury, Yorke Peninsula (R.T.). This species is very closely allied to P. australis, Sow., which is probably identical with P. asperrimus, Lamarck, but as my comparisons have been made with what is certainly the former, my remarks have reference only to it. The chief differences observable are the lamelliform ornamentation of the convex ribs and riblets, whilst in P. australis they are angular, and beset with distant scaly serratures or spinous scales; moreover the valves, especially the left valve, is more convex. The young of the two species are much alike, having simple ribs, developing with age a riblet on each side. Rarely does P. australis acquire more, but P. antiaustralis does so as a rule, and aged examples exhibit two or three on each flank, and often one in the furrow, whilst the concentric lamellae are continuous across the furrows. The ears of the fossil species are larger, and the shell attains to greater dimensions. P. antiaustralis, however, exhibits variations in the degree of convexity of the valves and ribs, whilst P. australis —the commonest shell on the S. Australian coast— is true to its type; nevertheless, it is easy to separate the species. P. actinoides, Sowerby, of the Chilian Tertiary, is apparently a near ally.» RALPH TATE, 1886
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R. Tate, 1886, plate 9.
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