Body long and cylindrical with up to 120 segments.
Upper lip low, very narrow. Buccal segment laterally forming prominent triangular lobes. Eyespots present.
One pair of arborescent gills (on segment 2). Gills with very thick stems and more or less developed crowns.
Distinct, strongly curved lateral lobes on segment 3. 14-15 ventral shields on thorax.
Sixteen thoracic chaetigerous segments.
Notopodial chaetae from segment 4. Notopodial capillaries with smooth tips. Uncinigerous tori from segment 5. Uncini in double rows on segments 11-19.
Notopodial chaetae smooth, with relatively narrow brims and long tips. Uncini with one big and several smaller teeth.
Pygidium with a wreath of 6-12 stout papillae.
Up to 150 mm for 120 segments.
Irregularly curved, thin secretion layer encrusted with fine and coarse sand and fragments of plants and animal shells.
In life yellowish to reddish, with brown spots or bands on the dorsum, tentacles spotted, gills red. In alcohol brown or pale yellow.
On sand, often with shells, or among algae; upper sublittoral to about 1000 m.
Eastern North Atlantic to the Cameroons, Mediterranean, Labrador, West Greenland, Canadian and Alaskan Arctic, White Sea, Siberian Arctic, Bering Sea, Sea of Okhotsk; East Greenland, Svalbard, Barents Sea, Iceland, Norwegian Sea, Norwegian coast from Hordaland to Finnmark, Danish west coast, Norfolk.