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''Amphicyclotulus amethystinus'' is a species of tropical land snail with a gill and an operculum, a terrestrial gastropod mollusk in the family Neocyclotidae. == Shell description == The shell is smooth, shining, not striate spirally, generally somewhat more depressed, deep chestnut or reddish brown. Whorls are a little flattened near the suture.〔 The species may have subtle spiral striation, although there exists considerable variation; axial growth lines are clearly visible.〔 The operculum is horny, diaphanous, concave externally, cartilaginous within, the nucleus projecting internally; with from ten to fourteen very narrow whorls, their rather lamellar outer edges slightly free.〔 ''Amphicyclotulus amethystinus'' has spiral threads absent or only weakly present.〔 There are found only two species in the genus ''Amphicyclotulus'' in Dominica. The other species is ''Amphicyclotulus dominicensis'' and it has spiral cords clearly present and raised.〔 Robert John Lechmere Guppy (1868)〔 noted that this species is not found above 1000 m. Although he recognized two “forms”, he did not recognize two separate species. George French Angas (1884)〔Angas G. F. (1884). "On the terrestrial Mollusca of Dominica, collected during a recent visit to that island". ''Proceedings of the Zoological Society of London'' 1883: 594-597, figs 1-3.〕 subsequently recorded “''Cyclophorus amethystinus''” from altitudes above 1200 m. Paul Bartsch (1942)〔Bartsch P. (1942). "The cyclophorid mollusks of the West Indies, exclusive of Cuba": 43-141. In: Torre C. de la, Bartsch P. & Morrison J. P. E. (1942). ''The cyclophorid operculate land mollusks of America". ''Bulletin United States National Museum'' 181: 1-306, pls 1-42.〕 restricted the name ''amesthystinus'' to Guppy’s var. β, the “smooth, shining, not striate spirally” form.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Amphicyclotulus amethystinus」の詳細全文を読む スポンサード リンク
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