(M. Sars, 1862)
Prostomium with anterior part crescent-shaped, bearing paired lateral antennae and paired palps laterally; posterior part nearly square, with median antenna and four eyes arranged in a rectangle. Antennae and palps short, awl-shaped, subequal. Caruncle a simple sinuous crest, extending posteriorly on first three segments. Ventral mouth surrounded by anterior part of prostomium and anterior three chaetigers.
Gills with a few finger-shaped filaments start on chaetiger 2 and continue on all segments.
Dorsal and ventral cirri with basal joint. Capillary notopodial chaetae smooth or serrated, other notopodial chaetae harpoon-shaped, or forked, some are spear-shaped or arrowhead-like. Neuropodial chaetae forked, some arrowhead-like (P. borealis-chaetae).
Anus terminal, with median oval papilla.
Up to 44 mm for 23-77 segments.
Pale yellow to pale vermilion.
On different kinds of substratum: shelly sand, mud, gravel, sand and pebbles, also among corals, algae, and under stones. Intertidal and shallow subtidal.
In North Atlantic waters and the Mediterranean, northern parts of North Sea and the English Channel.