A scale-worm with a relatively wide body.
Prostomium bilobed with a peak on each lobe, median and lateral antennae papillate and a pair of palps. Two pairs of eyes, the anterior pair on the line of greatest width, the posterior pair in front of the rear margin. First segment bearing three chaetae and a pair of dorsal and ventral tentacular cirri. Scales are oval to round, the surfaces covered with scattered short, delicate, slender papillae, with or without clavata tips (B. groenlandicus-scale). Notopodia are small mounds with a ventral acicular ligule and numerous chaetae (B. groenlandicus-parapodium). Notopodial chaetae weakly bent, with rows of spines. Neuropodia are well developed with an anterodorsal ligule and chaetae in rows. Neuropodial chaetae very long, filamentous with a long spinose part and capillary tips (B. groenlandicus-chaetae).
Up to 70 mm for 39 chaetigers.
Dorsally brown with two light transverse bands. Ventrally grey to colourless. Scales with brown pigment medially and posteriorly.
In the Skagerrak on silt and clay at 345 m.
Arctic, North Atlantic to Skagerrak. Also off Newfoundland, Gulf of Maine, Massachusetts.