(Adams, 1800)
Description (shell):
Shell solid, opaque, regularly conical, with six or seven slightly tumid whorls, apex rather blunt. Sutures shallow, slightly channelled; last whorl with spiral striae, often restricted to and more obvious at base. Aperture ear-shaped, with shallow anal sinus where outer lip abuts tangentially to last whorl, peristome somewhat thickened; umbilicus occluded by inner lip, though umbilical groove remains (C. trifasciata-drawing).
Size:
Up to 4 x 2 mm.
Colour:
Commonly yellow-brown, with three spiral brown bands on last whorls, one or two on whorls of spire; var. rupestris uniform cream or white; uniform black or dark purple shells occasionally found.
Animal:
Body of typical rissoid pattern; mantle edge smooth, with short pallial tentacle on the right; metapodial tentacle short, broadly triangular not reaching edge of foot.
Habitat:
Common in silty crevices or under stones from MTL downwards. Var. rupestris is confined to crevices and appears to favour exposed shores; it does not appear to mix with banded shells.
Distribution:
Distributed from Bay of Biscay to west coast of Norway. On Channel and British North Sea coasts; absent from continental shores of the southern North Sea (Distr. C. trifasciata). |
