1. 6.5mm juv., 10mm juv., 12mm juv., 10.2mm adult, 12 mm adult. LWS, Scapa Flow, Orkney. As shell grows, body whorl extends towards the spire eventually overwhelming it, while the aperture becomes a slit. Last juv. stage can be larger than early adult.
2. 6.5mm juv., 10mm juv., 12mm juv., 10.2mm adult, 12 mm adult. LWS, Scapa Flow, Orkney. As shell grows, body whorl extends towards the spire eventually overwhelming it, while the aperture becomes a slit. Last juv. stage can be larger than early adult.

6.5mm juv., 10mm juv., 12mm juv., 10.2mm adult, 12 mm adult. LWS, Scapa Flow, Orkney. As shell grows, body whorl extends towards the spire eventually overwhelming it, while the aperture becomes a slit. Last juv. stage can be larger than early adult.