Lobatus costatus: Shell sculptured with low, revolving ridges, which become mere threads on'the spire; whorls of the spire nearly flat, with occasional, irregular tubercles; on the back of the shell at the shoulder there are several strong tubercles or knobs, and below these on the body whorl the surface is pinched up into wavy folds; lip very thick, smooth; the subbasal notch wide and shallow; basal notch shallow. Color white, sometimes marbled indistinctly with brown.
Length, 160; diameter, 110 mm.