Shell to 33.0 mm in length, moderately light in weight, width 28-39% of length, teleoconch of 7-8.2 whorls which are subangulate at the shoulder, protoconch of 4.5-5 glassy brown embryonic whorls. Sculptured with keeled, narrow spiral cords which number 2-4 on the penultimate and 9-12 on the body whorl, siphonal fasciole with 4-6 oblique cords; interspaces concave but not as "V'-shaped as in S. sulcata, sculptured with axial striae, striae coarse and wider spaced on the spire whorls but usually becoming finer and more numerous on the body whorl; interspaces are either devoid of spiral sculpture or have a very fine central spiral groove or thread. Aperture equal in height or longer than the spire, height 49-60% of length, smooth within, outer lip fluted on edge, columella with 3-4 oblique folds, last anterior fold frequently weak, siphonal notch distinct. Base color white to ivory, spiral cords lined with brown, many individuals with an additional ornamentation of a dilacerated brown band of blotches situated between the first and fourth anterior body whorl cords, and brown axial streaks. Aperture white or stained with orange-brown, columella in some individuals bordered with golden-brown. Periostracum thin yellowish-brown and translucent.
Radula moderate in size, ca. 23% of shell-length, containing 55 rows of teeth + 8 nascentes; rachidians rectangular but with a thin, triangular, knob-like extension and 2 very long cusps, 2-3 small central cusps and 2-3 flanking side-cusps; laterals broader than rachidians and with 19-26 sharp denticles, third or fourth anterior cusp thick and long.

The species superficially resembles Subcancilla sulcata Swainson in Sowerby, but it is thinner and lighter in weight, the sculpture is less coarse, spiral cords are less prominently elevated and interspaces less concave, the axial striae are finer, whorls more shouldered and the periostracum is thinner, yellowish-brown and translucent.

Range - From the Gulf of California to the Galapagos Islands and Ecuador. In sand and mud, from the intertidal zone to 165 m.