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''Planorbarius corneus'', common name the great ramshorn, is a relatively large species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails, or planorbids, which all have sinistral or left-coiling shells. 〔 Marshall, B. (2014). Planorbarius corneus (Linnaeus, 1758). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=819958 on 2014-11-06 〕 The shell of this species appears to be dextral in coiling, even though it is in fact sinistral or left-handed. ==Description== :''For terms see gastropod shell'' All species within family Planorbidae have sinistral shells. ''Planorbarius corneus'' is the largest European species of ramshorn snail (family Planorbidae), with a shell typically measuring across when fully-grown. The coiled shell has between 3 and 4.5 rounded whorls with deep sutures, the last whorl predominating. The upper side is weakly depressed and the lower side is deeply depressed (flattened on the underside but spire recessed on the upper side). There is no keel. The shell is light yellowish with a brown, reddish or greenish periostracum, radially and spirally weakly striated. The aperture is wide and almost circular. The animal is brown or reddish. 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「Planorbarius corneus」の詳細全文を読む スポンサード リンク
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