Body of this scale-worm long, slender. Dorsal surface smooth with a raised central platform and 5 pairs of ctenidia on the first 7 chaetigers, ventral surface smooth.
Prostomium rounded to oval with a median antenna with short, thick basal joint with an ear-shaped process on either side, without eyes. First segment with two bundles of fine, simple, serrated chaetae on each side. Scales overlap, covering the body. They occur on segments 1, 3, 4 and 6, then alternately to the 26th and then on all segments. The first pair are rounded, the rest kidney-shaped. All scales with smooth surfaces. Anterior scales with up to 32 long papillae on the outer margins, absent in posterior scales. Three ctenidial cushions and a branchial cirrus attached to the dorsal surface. Notopodia with numerous chaetae and three finger-like projections. Notopodial chaetae thin, very finely and densely toothed. All neuropodial chaetae compound; the upper ones with toothed shaft and longer and shorter pseudoarticulate blades, lower ones with smooth or toothed shafts and simple or multiarticulate blades with bidentate tips.
Up to 120 mm for 120 segments.
Body and scales without pigment.
Arctic, North Atlantic to western Norway and Skagerrak.