Shell small, white, semi-transparent, ovate, spire hidden. Aperture narrow above, but widening considerably towards the rounded front. Columella convex, bearing about nine plications, of which the first three are strong. Those above are very much smaller. Outer lip rises above the summit, is strongly thickened, and simple.
Length 2. mm Breadth 1.4 mm.
Type, from 40 fathoms, off Thouin Bay, with about thirty others. It forms one of a small group in company with M. pumilio, Tate and May, and M. flindersi, Prit. and Gat., of which pumilio is intermediate, and possibly they are all variants of one species.