1. Juvenile. Height 10 mm. At this stage, the aperture has become a slit, though relatively wider than on the adult. The spire is becoming enveloped by the final whorl, and there are signs of adult shell ridges developing. LWS Scapa Flow, Orkney April 1975.
2. Juvenile. Height 10 mm. At this stage, the aperture has become a slit, though relatively wider than on the adult. The spire is becoming enveloped by the final whorl, and there are signs of adult shell ridges developing. LWS Scapa Flow, Orkney April 1975.

Juvenile. Height 10 mm. At this stage, the aperture has become a slit, though relatively wider than on the adult. The spire is becoming enveloped by the final whorl, and there are signs of adult shell ridges developing. LWS Scapa Flow, Orkney April 1975.