As Tromina unicarinata
"Shell minute, violet-hued, oblong-fusiform, smooth, the upper whorls medially keeled and angulate, sharply incut above, subcylindrical below, the canal well distinguished, moderately open, the aperture open and confluent with the canal.
"One specimen seen. Whorls six, the first two very smooth embryonic whorls. The remaining whorls are distinctly carinate, the carina prominent but quite obtuse. The striae are of irregular growth, broadly spaced. The aperture, with canal, makes up foursevenths of the total, and the canal is scarcely distinct from the remainder of the aperture.
"Color violet as in chalcedony, the keel white." Known to us only from the Magellanic region.