It is more or less inflated, generally pretty thin, enamelled, and provided with parallel, longitudinal, inclined and acute ribs.The body whorl is much larger than all the others together.

The animal has a flattened head, which supports a pair of long, thick, and conical tentacles, with a small protuberance at their base, internally, where the eyes are situated.

The locomotive organ is very large, very broad at the anterior part, which is ear-shaped, and distinguished by a deep emargination upon each side.The posterior extremity is caducous, and destitute of an operculum.

The anterior broader, arcuated, ear-shaped, with a marginal furrow, and joined to the posterior part by a kind of neck.

When the animal is violently disturbed, it breaks off the posterior extremity of its foot, in order to withdraw itself more completely within its shell.

On the opposite side are situated, in female specimens, the rectum and the uterus; and in the male a deferential canal and a penis.

[3] This genus are voracious nocturnal predators of benthic crustaceans on sandy bottoms, capable of eating crabs as large as themselves.