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Show 1890.] MARINE MOLLUSCA OF ST. HELENA. 307 features of this species. It probably attains larger dimensions than those given above. The angle formed by the divergent dorsal slopes is about 116 degrees. L I M E A SARSII, Loven. Limea sarsii, Loven, Index Moll. Scandin. p. 32. Lima sarsii, Jeffreys, Brit. Conch, vol. ii. p. 78, vol. v. p. 169, pi. 25. fig. 1. Lima (Limatula) sarsii, Jeffreys, Proc. Zool. Soc. 18/9, p. 562. Limatula crassa (Forbes), Sars, Moll. Reg. Arct. Norv. p. 26. Hab. North Sea ; Mediterranean ; Atlantic from west of Ireland to Portugal. A number of odd valves were dredged in deep water by Capt. Turton. The occurrence of this species so far south has not been previously noted. O S T R E A , sp. A species of oyster occurs in very shallow pools on tiie east coast of St. Helena, which, possibly, has not been previously described. The same form is met with at Cape Verde Islands. It is thick, solid, irregularly rounded, with the surface ridged and the margin dentate and interlocking like O. folium and other species. The interior is dirty whitish, stained more or less with olive-brown or yellowish olive, and the outer margin is finely wrinkle-striated. O S T R E A CRISTA-GALLI, Linn. Hab. St. Helena, 50-60 fathoms (Melliss). I have not seen the specimens collected by Mr. Melliss and identified by Jeffreys as belonging to this species, which is usually regarded as an Indian-Ocean form. I think it probable that they belong to the same species as those collected by Capt. Turton, which I have not ventured to identify. Having strongly dentate margins to the valves, they may have been mistaken by Jeffreys for the Linnean species. APPENDIX. The following species were all taken at St. Helena upon floating seaweed, but, as I have already shown1, are to be regarded as South- African forms. I. GASTROPODA. PLEUROTOMA (MANGILIA) ATLANTICA. (Plate XXIV. fig. 11.) Testa elongata,pallide fusca, linea alba cincta ; anfractus 5, primus maximus, globosus, nitidus, albidus, cceteri convexiusculi, plicis longitudinalibus 10-12 instructi, liris striisque spiralibus ornati anfr. ultimus elongatus, infra medium parum contractus ; apertura angusta, longit. totius T 5-j adcequans; columella alba ; labrum vix incrassatum, superne minime sinuatum. Longit. 6 millim., diam. max. 2\. This species is remarkable for the large size of the apex. The 1 Pp. 247, 248. |
