(Stimpson, 1854)
Description:
Body small, cylindrical, with up to 50 chaetigers; seven thoracic chaetigers.
5-7 pairs of radioli. No eyes on peristomium.
Operculum with a flat or concave distal plate and a cup-shaped ampulla below; peduncle long, bare and cylindrical, arises between the first and second radioli of either right or left side.
Collar with lateral and dorsal incisions. Thoracic membrane short, with dorso-lateral margins reaching only as far as segment 2.
Collar chaetae of two types, capillary and geniculate, the latter with a toothed fin distally and with some round teeth on the basal part. Apomatus-chaetae starting at chaetiger 3. Abdomical neuropodial chaetae are geniculate with strong teeth on the distal part.
Thoracic uncini with a single row of teeth, in abdomen uncini with 3-4 longitunival rows of teeth (C. serrula-chaetae).
Size:
Up to 20 mm long for over 50 segments.
Tube:
White and smooth with triangular cross section. With an irregularly toothed medial keel; breeding specimens develop a calcareous brood-chamber on each side of aperture.
Colour:
In alcohol yellowish.
Habitat:
On stones and shells; lower shore and sublittoral. 1-300m depth.
Distribution:
Northern species widespread in the North Atlantic and parts of the North Sea; Skagerrak, Kattegat and Öresund.
Remark:
Tubes of non-brooding specimens are easily confused with young Pomatoceros.