(Norman, 1862)
Description:
Carapace large (about 1mm long). Dorsal margin with two rounded but distinct angles: one at the maximum height, one-third of the length from the anterior, the other one-quarter of the length from the posterior. Anterior margin broadly and evenly rounded, posterior margin narrowly rounded. Right valve with about eight posteroventral marginal denticles. Ventral margin almost straight. Colour of living specimens purple/brown. Male copulatory appendage large with a distinctive median process and a curved, pointed distal process (P. mytiloides 14 ).
Habitat:
It has been recorded from numerous, mainly northerly, British localities, at depths down to 80 metres on a variety of coarse substrates.
Distribution:
Sars recorded this species from sand in the Laminaria zone in S Norway. We have not confirmed records from France and the Mediterranean.