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Show 1887.] MOLLUSKS OF THE VITI ISLANDS. 309 Realia (Omphalotropis) perforata, Mousson, Journ. 1871, p. 27; Pfeiffer, Mon. Pneum. iv. p. 222. de Conch. p. 222.' The type specimens of O. zebriolata and O. perforata were found by Dr. Graffe at " Uvea" or Wallis Island, one of the northern islands of the Tonga group. Having personally collected hundreds of examples of both forms in the same locality, and as they gradually intergrade, I have united the two species. Dr. Graffe also detected it on the neighbouring island of Futuna and on the low coral-islands of Ellis group. He likewise obtained the form O. zebriolata at Kanathia, Viti Islands. Mr. Pease wrongly assigns it to Samoa. It may be distinguished by its ovate-conical form, smooth surface, fissured base, and variable colour-rose-red, pale luteous, violaceous brown, often pale banded at the periphery ; sometimes with pale dots or longitudinal flexuous or zigzag lines. The basal keel is contiguous to the umbilical fissure. The pyriform aperture is usually concolor and the glazed parietal wall is frequently reddish brown. Length 5 to 7 millim. It is shaped like the well-known O. huahinensis. 9. OMPHALOTROPIS ROSEA (Gould). Cyclostoma roseum, Gould, Proc. Bost. Soc. Nat. Hist. 1847, p. 205 ; Expl. Exp., Shells, p. 105, fig. 121 ; Petit, Journ. de Conch. 1850, p. 47. Omphalotropis rosea, Pfeiffer, Proc. Zool. Soc. 1854, p. 307 ; Consp. Cyclos. no. 47; Mon. Pneum. i. p. 308, iii. p. 176; H. & A. Adams, Gen. Moll. ii. p. 300. Hydrocena rosea, Pfeiffer, Mon. Pneum. ii. p. 162. Assiminea rosea, Martens, Ann. & Mag. Nat. Hist. 1866, xvii. p. 206. Through the kindness of Mr. E. L. Layard, I have received an adolescent example of Gould's O. rosea ; but, unfortunately, the kind donor cannot give me any information in regard to the exact locality except the comprehensive one " Fiji." I am inclined to believe it inhabits the small Windward Islands. It may be distinguished by its large size, elongate-conical shape, rather solid texture, 6-7 whorls, and rose or luteous horn-colour. The conspicuous basal keel is close to the slightly perforated umbilicus. Length 8-9, diam. 4^-5 millim. 10. OMPHALOTROPIS BIFILARIS, Mousson. Omphalotropis bifilaris, Mousson, Journ. de Conch. 1865, p. 183 ; Pease, Journ. de Conch. 1869, p. 146; Proc. Zool. Soc. 1871, p. 476 ; Paetel, Cat. Conch, p. 124 ; Schmeltz, Cat. Mus. Godeff. v. Realia (Omphalotropis) bifilaris, Mousson, Journ. de Couch. 1S69, p. 353, 1870, p. 194 (var. angusta), 1871, p. 29; Pfeiffer, Mon. Pneum. iv. p. 232. Obtained by Dr. Graffe at Kanathia, and the var. angusta in the interior of Viti Levu. The latter has a smaller basal fissu.e, and the |