Brissopsis lyrifera

(Forbes, 1841)

Body oval, arched, sloping anteriorly, up to 70 mm in length; coloured mostly reddish-brown.
Test: The frontal ambulacrum is rather deep, forming a conspicuous notch in the anterior end of the body. The posterior petals are shorter than the anterior ones, and are diverging. Beside the subanal fasciole, there is a very conspicuous, lyre-shaped (hence the species' name) peripetalous fasciole encircling all five petals of the ambulacra on the upper side of the body. A dental apparatus is lacking (B. lyrifera test top, B. lyrifera test side).

Globiferous pedicellariae of one kind, rather conspicuous, invested by a thick glandular skin. The valves are short, ending in two rather long teeth. The stalk has some long, projecting thorns. The tridentate pedicellariae of various forms, with 3 more or less leaf-shaped blades. The rostrate pedicellariae are very slender. Triphyllous pedicellariae are not characteristic (B. lyrifera pedicellariae).

It is often found in large numbers buried in soft mud bottoms; from depths of 5 m to at least 500 m.

The species is common in the whole North Sea. Elsewhere it is distributed from the Lofoten (Norway) and Iceland to the Mediterranean and S. Africa. It is also found on the east coast of N. America, but is not known from Greenland.