Parvamussium torresi (E. A. Smith, 1885)
SMITH, E. A. 1885. Report on the Lamellibranchiata collected by H.M.S. Challenger during the years 1873-76. In C. W. Thomson & J. Murray: Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-1876. Zoology, 13: 1-341, pls. 1-25 [p. 311, pl. 23, figs. 3, 3a, 3b]
1885 Amussium [sic] torresi E. A. Smith, 1885
E. A. Smith, 1885, plate 23.
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«Testa parva, compressa, tenuis, subpellucida, alba, leviter inaequivalvis, valvae diverse sculptae, marginibus supernis levissime concavis. Valva (dextra ?) paulo convexior, nitida, incrementi lineis minime conspicuis sculpta, sinistra liris confertis tenuissimis concentricis ornata. Auriculae parum inaequales, postica paulo majore, in valva sinistra striis paucis radiantibus prope marginem obliquum dorsalem signata. Pagina interna nitens, radiis tenuissimis duodenis inaequalibus instructa.
This species, so far as at present known, appears to he of small size. It is very thin, scarcely gaping at the sides, slightly inequivalve, very much compressed, and semitransparent white. The valves are about as long as high, have acute beaks and faintly concave dorsal slopes, the apical angle being of about 105 to 110 degrees. The valve regarded as the right is a trifle deeper than the other, and nearly quite smooth and glossy, exhibiting only the feeblest indications of lines of growth, the left valve, on the contrary, being prettily ornamented with very fine and close-set concentric lirae. The auricles are unequal in size, the posterior being considerably larger, that of the left valve exhibiting a few (two or three) striae near the dorsal slope. The interior is glossy, and strengthened with twelve slender radiating lirae, of which the two uppermost are very small and insignificant.
Length 8 mm., height 8½, diameter 2. Habitat.— Station 185b, cast of Cape York, North Australia, in 155 fathoms; coral sand. This species differs from Amussium caducum not only in having more internal costellae but also in form and the sculpture of the exterior.» EDGAR ALBERT SMITH, 1885
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