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''Marginellona gigas'' is a species of very large deepwater sea snail, a marine gastropod mollusk in the family Marginellidae. This species was originally thought to be a volute, in the family Volutidae, but it is in fact a giant marginellid. 〔 Rosenberg, G. (2012). Marginellona gigas. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=473905 on 2012-06-27 〕 This is the only known species in the genus ''Marginellona'', in other words, ''Marginellona'' is a monotypic genus. ==Shell description== The shell can be as large 157 mm. It is thin, translucent, porcellaneous, and narrowly ovate in shape. The protoconch consists of 2-2½ rapidly expanding (diameter 0.5 mm to 11.5 mm in 2 whorls), smooth, conical, glassy whorls, deflected from coiling axis of teleconch by up to 15°. The transition to teleconch is abrupt, marked by a growth line, and accompanied by the formation of thin parietal callus. The teleoconch has up to 3 smooth, inflated, convex, rapidly descending whorls. The suture has abutting whorls. The shell surface is smooth, glazed, and lacking spiral and axial sculpture. The aperture is ovate, narrow posteriorly, broad anteriorly. The outer lip is smooth. The inner lip is smooth, with thin, whitish inductural overglaze in some specimens. The columella has a single sharp, axially-oriented columellar fold and a sharp siphonal fold of nearly equal magnitude. The outer shell surface is uniformly tan to greenish-tan; the aperture is darker brown. 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「Marginellona gigas」の詳細全文を読む スポンサード リンク
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