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Show 1884.] OF THE 'CHALLENGER' EXPEDITION. 271 7, 8, 13, and 14 being from Ovalau; 2, 4, 9, 10, 11,12, and Kandavu, and No. 16 from the Wai Levu, Viti Levu. HELIX (TROCHOMORPHA) LATIMARGINATA. (Plate XXIII. figs. 14-14 6.) Shell depressed, acutely keeled, arched above, very slightly convex beneath, deeply and rather narrowly umbilicated, uniformly dull pale brownish. Whorls 5, slowly increasing; the last convex above, compressedly broadly marginate above the suture, sculptured with oblique lines of growth, last near the aperture but very slightly broader than the preceding, compressed both above and below the sharp carina. Aperture small, with the basal margin receding and thickened. Greatest diam. 15 millim., smallest 14; height 7. Umbilicus about 2| wide. This species belongs to the same group as H. eurydice, Gould, H. cressida, Gould, II. swainsoni, Pfr., H. apia, Horn. & Jacq., some others, but does not seem to fall among the varieties of any. The narrowness of the last whorl, the broad margination above the suture (the margination being a little darker than the rest of the surface), the dull uniformly pale brownish colour, the thickened lower margin of the aperture, and the flattish lower surface are the principal distinguishing features of this species. FRIENDLY ISLANDS. Eight species collected at Tongatabu have all been previously recorded from these islands, and, with the exception of Nanina tongana, are not restricted in their distribution to this group, the majority having been met with at the Samoa Islands somewhat further north. The species are-1. Nanina perpolita, Mousson; 2. Ar. tongana, Quoy & Gaimard ; 3. Helix (Patula) gradata, Gould; 4. Helicina fulg or a, Gould; 5. H. musiva, Gould; 6. Om-phalotropis variabilis, Pease ; 7. Physa sinuata, Gould ; 8. Melania inhonesla, V. d. Busch. SOCIETY ISLANDS. The following eight species were collected at Lake Waihiria on the island of Tahiti. 1. NANINA TONGANA, Quoy & Gaimard. A single specimen only was obtained, agreeing in every respect with others collected at Tongatabu. This appears to be the same species as Helix conula of Pease, also founded on Tahitian shells. 2 & 3. PARTULA, sp. Seven specimens of this genus in worn condition apparently belong to two distinct species which I have been unable to identify, and which it would be unwise to describe as new without paying special attention to the whole of the genus. |