Shell elongate-oval, of 5 whorls, including a blunt protoconch of 2 convex whorls, apparently smooth, but microscopically minutely punctate from crowded spiral and axial lirae; the latter become more conspicuous just before the abrupt termination of the protoconch: suture simple, impressed. Spire-whorls convex, suture distinct, bounded below by a round spiral. Body-whorl oval, tapering anteriorly; base very faintly excavate. Aperture oblique, narrowly oval ; outer lip thin, simple, corrugated by the spirals, convex in profile, with a shallow, round sinus near the suture; inner lip a glaze, thicker on the columella, which is straight and forms a round, open angle with the slightly concave base of the whorl. There are four spirals in the first whorl, five in the second, and seventeen in the body-whorl, becoming crowded towards the snout, about one-third the width of the concave interspaces, which are well roughened (and the spirals slightly so) by crowded fine distinct oblique axial lirae. The spirals are opaque-white in colour, and are faintly articulated with tiny brown subdistant spots; the labrum is brown-stained outside. In some examples there is a row of brown blotches in each whorl, running round the body-whorl to a little above the middle of the labrum.
Length, 4 mm.; length of the body-whorl, 2.3 mm; breadth, 1.7 mm.

It resembles M. angusta, but this is longer and has eight spirals in the penultimate and twenty-eight in the body-whorl. It differs from M. paula, var. leuca, in having fewer spirals, more convex whorls, in an excavate depression below the spiral which bounds the suture, and in the more convex whorls and deeper suture of the protoconch.

Southern Australia.