3mm. Narrowly high spired with cylindrical, smooth, glossy protoconch of about 4.5 whorls. Spire whorls have strong, low, slightly oblique ribs (about 13 on last whorl) meeting irregularly at deep sutures. Obscure spiral threads between ribs. Spiral cord encircles base. Outer lip thick, reflected, with radial rows of punctae on ventral face. White except for amber protoconch. Habitat: deep water. Distribution: Gulf of Oman.

Opalia (Pliciscala) mammosa (Melvill & Standen, 1903) (Figs 229 & 230) Like O. corolla, this species was described based on material found in the Gulf of Oman at a depth of 156 fathoms. However, it is not restricted to that locality and has been found in the Gulf of Aqaba and the Red Sea. It is a tiny species reaching a height of only 3mm. It is a slender species, with 4 teleoconch and 3 brownish protoconch whorls. There are about 12 low costae on the last whorl. The suture is crenulate. The aperture is almost round and the outer lip is thickened. There is no basal ridge. We have reproduced de Boury's photograph of the type specimen of S. (Nodiscala) alba de Boury, 1911, which appears to be a synonym. While this species resembles O. methoria, the sutures on the latter species are not crenulated.