Amaobunegai - Amaobunegai

A gastropod shell of the family Neritidae in the class Gastropoda of the phylum Mollusca. It is one of the most common shells found on rocky shores from the Boso Peninsula south to the Indian Ocean and the Western Pacific Ocean. It is hemispherical, about 25 mm high and 30 mm in diameter, with a hard shell, a low spiral spire, and a large body layer. The shell surface is black with yellow-white spots and about 20 low spiral ribs. The shell opening is crescent-shaped, with a rounded outer lip and a straight axial lip with several shallow, weak notches, and the yellow-white slip layer that spreads there has small warts. The operculum is calcareous and crescent-shaped. It lays oval egg capsules on rocks in summer and autumn.

[Takashi Okutani]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

軟体動物門腹足綱アマオブネガイ科の巻き貝。房総半島以南からインド洋、西太平洋の岩磯(いわいそ)にもっとも普通にみられる貝の一種。殻高25ミリメートル、殻径30ミリメートルぐらいの半球形で、殻は堅く、螺塔(らとう)は低く、体層が大きい。殻表は黒色地に黄白斑(はん)があり、低い螺肋(らろく)が20本ほどある。殻口は半月形で、外唇は丸く、軸唇はまっすぐで数個の浅く弱い切れ込みがあり、そこに広がる黄白色の滑層には小さいいぼがある。蓋(ふた)は石灰質で半月形。夏、秋季に岩の上に楕円(だえん)形の卵嚢(らんのう)を産み付ける。

［奥谷喬司］

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