Body of this scale-worm small tapering posteriorly. Dorsal surface smooth, ventral surface papillate in the anterior region.
Prostomium triangular with a median antenna, a pair of palps, two pairs of eyes touching coalesced or slightly separated.
First segment without chaetae, with a pair of dorsal and ventral tentacular cirri, in cirrophores which extend to ensheath the base of the palps. Facial tubercle absent.
Scales overlap but do not cover the anterior dorsal surface when the proboscis is retracted. They occur on segments 1, 3, 4 and 6 then alternately to the 22nd and then on all segments. The first pair are round, the rest oval to kidney-shaped. All scales have long filiform papillae on the outer margins and a few on the surfaces. Two ctenidial cushions attached to the dorsal surface of notopodia appear on the 2nd segment and three appear on all remaining segments.
Notopodia are small mounds with chaetae arranged dorsally in a semicircle. Notopodial chaetae of two kinds: 1) fine capillaries; 2) geniculate capillaries. Neuropodia, projecting beyond notopodia with only a few papillae and chaetae in a bundle. Neuropodial chaetae shafts spinose or smooth, stout blades with unidentate tips (P. synophthalmica-detail).
Up to 8 mm for 50 chaetigers.
Littoral to shallow sublittoral.
Orkney, eastern Scotland, English Channel, North Wales and the south coast of Ireland, Nova Scotia, Norway, Mediterranean, West Africa and South Africa.