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Show 1887.] MOLLUSKS OF T H E VITI ISLANDS. 171 8. MICROCYSTIS PERPOLITA. Nanina (Microcystis)perpolita, Mousson, Journ. de Conch. 1869, p. 326, pl. 14. fig. 1; 1870, p. 113; 1871, p. 8, var. solida; Schmeltz, Cat. Mus. Godeff. v. p. 90. Helicopsis perpolita, Pease, Proc. Zool. Soc. 1871, p- 475. LIelixperpolita, Pfeiffer, Mon. Hel. vii. p. 65. This species was found by Dr. Graffe on Viti Levu. It also inhabits Tonga and tbe Samoa Islands. It is a convexly depressed, pellucid, highly polished, yellowish horn-coloured species with 4\ whorls. 9. MICROCYSTIS STEARNSEANA, sp. nov. Shell small, imperforated, depressedly globose, pellucid, smooth, shining, luteous horn-colour; spire convexly rounded, apex depressed ; suture linear, narrowly margined; whorls 5, flatly convex, last one not descending in front, rounded, base convex ; aperture nearly vertical, roundly lunate ; peristome straight, acute, regularly curved, margins remote, not converging ; columella with a white, prominent, nearly horizontal tooth-like fold ; within the base of the aperture, a short distance from the margin, are two sublamelliform white teeth, the upper one the larger, crest-like, the smaller one close to the columellar fold. Major diam. 3, height 2 millim. Hab. Viti Islands. Several examples found beneath rotten wood at Vanua Balavo, and a few were obtained under dead leaves at Uea or Wallis Island. It is closely allied to Nanina (Gastrodonta) ensifera, Mousson, a Samoan species, which is smaller, more depressed, the body-whorl being subangulated and more depressedly rounded. I name this singular species after m y friend R. E. C. Steams, Esq. Genus TROCHONANINA, Mousson. 1. TROCHONANINA SAMOENSIS. Nanina samoensis, Mousson, Journ. de Conch. 1865, p. 165. Helix samoensis, Pfeiffer, Mon. Hel. v. p. 70. Zonites (Conula) samoensis, Mousson, Journ. de Conch. 1869, p. 331 ; 1870, p. 116 ; 1871, p. 10; Paetel, Cat. Conch. 1873, p. 86 ; Schmeltz, Cat. Mus. Godeff. v. p. 90. Helix clayi, Liardet, Proc. Zool. Soc. 1876, p. 101, pl. 5. fig. 7. Microcystis samoensis, Garrett, Journ. Phil. Acad. Nat. Sci. 1881, p. 384. This minute species is generally diffused throughout the group. It is also common in the Tonga, Cook's, and Samoa Islands, and rare in the Marquesas. Under decaying vegetation. It is a perforated, thin, depressed, turbinated, reddish or brownish horn-coloured species, with five strongly convex whorls, the last one angulated on the periphery. |