Right: Columellar groove (1) also called chink or lacuna, next to aperture. Umbilicus concealed at this angle of view. Columellar lip (2), wide and white, slightly curved, between groove and aperture. Outer lip of aperture bends and continues as abapertural edge of groove (3). Parietal lip a whitish glaze on whorl surface (4). Green and yellow body visible through translucent operculum (5).
Left: Umbilicus viewed along the lacuna (6). Transparent periostracum projects beyond aperture lip (7).
Juvenile height 4.6 mm. Menai Strait, Wales. August 2013.
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