Phrontis antillara, common name the Antilles nassa, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.

The spire is composed of six or seven convex whorls, keeled and strongly folded.

It has, also, upon its entire surface, fine and numerous transverse striae.

The outer lip is margined, marked with brown spots and striated internally.

[2] This species occurs in the Caribbean Sea, the Gulf of Mexico and the Lesser Antilles; in the Atlantic Ocean off Brazil.