M. Sars, 1851
About a third of mid-dorsum without chaetae. Two large eyes dorsally and two smaller eyes ventrally. Caruncle extending posteriorly on to chaetiger 5. Each notopodium with five to six gills, branched dichotomously several times; terminal filaments conical, not thickened. Two dorsal cirri. Notopodial chaetae extending only slightly beyond the gills, shorter than neuropodial chaetae and of two kinds: 1) smooth, forked, one branch very much shorter than the other; 2) unequally forked chaetae with curved divergent branches, with strong serrations on inner sides. Neuropodial chaetae with curved hooked tips, with a strong lateral spur, some with an additional slender subterminal tooth.
Up to 10 mm for 19-30 segments.
Brick red to pale yellow.
In sand, mixtures of mud, shell and gravel and corals; from the shallow subtidal region to depths of more than 3000 m.
All over the North Atlantic and the Mediterranean.