Body long and slender with up to 30 chaetigers.
Prostomium semicircular with four eyes in a trapezoid arrangement and two ocelli. Palps rounded and conical, not fused, as long as prostomium or a little shorter. Median antenna longer than lateral ones. Lateral antennae longer than palps, flask-shaped or straight.
Dorsal tentacular cirri as long as lateral antennae, ventral a little shorter.
Dorsal tentacular cirri and dorsal cirri flask- or spindle-shaped.
Dorsal cirri on first parapodium a little longer than segment width, on the next parapodia equal to, or a little shorter than segment width. Ventral cirri about as long as parapodial lobes. Aciculae present. Blades of compound chaetae moderately long, unidentate. Additionally one upper and one lower simple chaeta present on the middle and posterior parapodia (B. limbata-detail). Pharynx with one anterior tooth.
Body up to 3 mm long for 26-30 segments.
Atlantic up to Mediterranean, English Channel to southern North Sea and Kattegat.