Early Pleistocene to Middle Pleistocene; Recent.
For information on the modern distribution of the species, see Malacolog.
Original Description (from Smith, M., 1940, p. 44):
"Shell of moderate size. Nucleus of 1.5 whorls, the portion following the first half rounded and prominent, very similar to M. cabritii nucleus. Anterior canal comparatively short, straight, tip not recurved. Edge of outer lip bearing inside a series of blunt inconspicuous and widely separated denticles; outer lip well denticulated with in addition about seven long low processes upon the adjacent inner wall. There are three varices upon each whorl together with secondary spineless intermediate ribs. Spiral threads of two sizes cover the surface and extend over the varices. Certain of the primary threads form spines on the varices, these spines of fairly uniform size and few in number adjacent to the anterior canal; early whorls of spire presenting a reticulated appearance. The holotype, in the writer's collection, measures: length 33 mm., breadth 20 mm. A fragment exhibiting the aperture agrees perfectly with the holotype. Named in honor of the writer's mother Annie Lum Smith."
To access this description in its original formatting through the Biodiversity Heritage Library, click here.