OCR Text |
Show 887.] MOLLUSKS O N T H E VITI ISLANDS. 169 It may at once be recognized by its large size (38 millim. in diameter), depressed turbinate form, yellowish or light brownish horn-colour with a wide fulvous-brown sutural band. 11. NANINA ASSAVAENSIS, n. sp. Shell imperforate, turbinately globose, indistinctly striated with rather coarse lines of growth, smooth, shining, subpellucid, smoky horn-colour; whorls 5, slightly convex, the last one obscurely angulated just above the periphery ; aperture oblique, orbicular-luniform ; peristome thin, straight; columella abbreviately reflected over the axis of the shell. Diam. 20, height 12 millim. Abundant beneath dead leaves at Naviti Island, one of the Assawa group. Genus MICROCYSTIS, Beck. 1. MICROCYSTIS UNISULCATA. Nanina unisulcata, Mousson, Journ. de Conch. 1865, p. 191; (Microcystis) 1870, p. 113; (Thalassina) Paetel, Cat. Conch. 1873, p. 85; Schmeltz, Cat. Mus. Godeff. v. p. 90. Helix unisulcata, Pfeiffer, Mon. Hel. v. p. 80. Helix (Petasia) unisulcata, Paetel, Cat. Conch, p. 96. Helix laqueata, Baird, Brenchley, Cruise of the ' Curagoa,' p. 446, pl. xl. figs. 8, 9. This peculiar species is widely diffused throughout the group, and, like all the Viti species, is found beneath decaying vegetation. It is the only species, so far as known, which exhibits a sculptured surface. The unisulcated whorls and more or less nodulous columella will readily distinguish it. 2. MICROCYSTIS KIOAENSIS. Nanina kioaensis, Garrett, Proc. Phil. Acad. Nat. Sci. 1873, p. 237, pl. 3. fig. 71 (" kiraensis " in error). Naninal taviuniensis, Liardet, Proc. Zool. Soc. 1876, p. 99, pl. 5. figs. 1, la, b. This very distinct species only occurred to my notice in the mountain-forests of Kioa Island. Mr. Liardet's Nanina taviuniensis, which he obtained at Taviuni and Gomea, differs only from our species in having the base minutely perforated. It may be distinguished by its depressed globose form, yellowish horn-colour, deep rounded body-whorl, and the prominent columellar fold. 3. MICROCYSTIS NODULATA. Nanina (Microcystis) nodulata, Mousson, Journ. de Conch. 1870, p. 114, pl. 7. Ag- 4 ; (Thalassia) Paetel, Cat. Conch, ed. 1873, p. 85. ' Helix nodulata, Pfeiffer, Mon. Hel. vii. p. 67. Discovered by Dr. Graffe on Vanua Balavo, one of the Windward Its chief characters are its depressed globose form, brilliant horn- |