Body long; thorax dorsally convex, laterally and ventrally flattened, abdomen tapering. Tentacles numerous, long. Upper lip low, covering the mouth dorsally and laterally. Three pairs of gills (on segments 2-4). Gills dichotomous branched with long tips and short, more or less flattened, stems. Distinct lateral lobes on segments 2 and 3. Thirteen ventral shields on the thorax. Notopodial chaetae from segment 4, subdistally denticulate. Seventeen chaetigerous thoracic segments. Prominent uncinigerous tori from segment 5, long on the thorax, short on the abdomen. Uncini in double rows on segments 11-20. Pygidium without appendages.
Up to 115 mm for over 50 segments.
A thin layer of secretion encrusted with mud, clay and fine sand grains.
In alcohol pale yellow or greyish.
On mud and fine sand; 15-600 m.
Franz Josef's Land, western Scotland, western Ireland, White Sea, Siberian Arctic, West Greenland, Canadian Arctic, Nova Scotia. East Greenland, Svalbard, Barents Sea, Iceland, Norwegian Sea, northern Norway and Trondelag, Skagerrak, Oslofjord, Swedish west coast.