The shell is irregularly oval, white, smoothish, but showing fine, close, concentric wrinkles, over the whole valve or only near the ends; polished, glossy, and marked with weak lines of growth near the beaks. Close to P. consanguinea (C. B. Ad.), but relatively longer and less rounded, and differing by the smaller size of the anterior left lateral tooth, which is only as high as the cardinals, while in P. consanguinea it is enlarged and higher.
Length 20.9 mm., height 16.3 mm., diam. 11.5 mm. Acapulco. 20 fathoms (Lowe), type 155592 ANSP.; paratypcs in Lowe coll. Guaymas, 20 fathoms (Lowe).