Shell of much the same general form as A. briareus, but having noduled instead of spinose ridges and a finer and less evident surface sculpture, which follows the incremental lines, and is not wavy, raised, and sharp, as in briareus. On the last whorl there are six basal, two peripheral, and three superior revolving ridges. The suture is channelled, and the middle one of the three upper spirals is smaller than the two others, which gives a slight tabulation to the spire. It has five whorls and a small smooth nucleus. Like A. briareus, there is hardly any varix at the aperture of the adult, though this is slightly reflected; the margin is machicolated by the squarish ends of the spiral ridges, when these are strong. The umbilicus is small, the base in the adult rounds into it, within there is a single rounded spiral ridge, but no spines or nodules. The outer basal spiral is larger than the others, and separated from the others by wider channels. The color is whitish, more or less maculated, or wholly overspread by a dull livid red, much less attractive than the delicate color of the preceding species. The size of the largest specimens is rather less than in briareus. Operculum horny. Max. alt., 6.0; max. diam., 6.0 mm.

Habitat. Station 2, in 805 fms.; Sand Key, in 15 fms.; Sigsbee, off Havana, in 127 fms. Also at Stations 2595, 2596, and 2612 of the U. S. Fish Commission, in 50-60 fms., twenty miles off the North Carolina coast, and at Stations 2317 and 2318, living, in 45 fms., off Key "West.