65mm. Thin (becoming thicker in large specimens), semitranslucent or opaque, spire angle about 20°. Each whorl has 2 strong, rounded keels, occasional spiral ridges and many, fine, spiral threads. Aperture thin-edged, squarish. Violet-white with brown mottiings and stripes (fading to yellow); fine, brown lines sometimes encircle whorls. Keels sometimes obsolete. Syn: T. torulosa Kiener, 1843-44 (sensu Bosch & Bosch, 1982:41, and others; the name is now applied to West African specimens.). A pure white form was named, unnecessarily, var. chionia by Melvill, 1928:102. Habitat: intertidal.