(Monterosato, 1890); Monterosato, 1890 ex de Boury ms.
The spire is usually straight. Whorls are extremely flat-sided and the sutures light. Varices ophistocline. There are only occasional indistinct growth lines. In side view the outer lip slants smoothly backwards to the surface of the last whorl. Last whorl occupies a little less than half of the shell height, the aperture between a quarter and a third; the breadth of the aperture is half its height, sometimes a little more.
Up to 6 x 2 mm.
On soft and gravelly bottoms 20-120 m deep. The way of life is unknown but they presumably parasitize some echinoderms.
Occurs from the Mediterranean to Scandinavia. Some rare records from the northern parts of the North Sea, off south-western shores of England, and the Channel Island (Distr. M. monterosatoi).