Lamarck, 1816
Description:
Body usually 20-75 mm long, sometimes more; mouth with 7 rings each of 5 teeth. Introvert 0.2-0.3 mm of total body length, marked by 25 longitudinal ridges. Rest of body with numerous rings. A tail arise ventrally to the anus, bearing numerous vesicular branches; base of tail sometimes partially enclosed through a swelling of the body.
Habitat:
In grey mud, from the mid-shore into the sublittoral.
Distribution:
Scandinavia; circumarctic.