Cancellaria stuardoi: Shell large, thin but sturdy, light brown under a thin but persistent light brown periostracum; whorls six, convex and slightly shouldered, suture deeply impressed. Protoconch lost; sculpture eroded on first two whorls. Axial ribs 18 to 20 per whorl, except on the final half whorl, where the ribs become more irregular and tend to be more broadly spaced from growth pauses; ribs crossing the whorls completely; ribs narrower than the interspaces; ribs posteriorly flexed near the suture. Spiral sculpture of broad, low ribs with more or less equal interspaces, 9 on the penultimate whorl and about 20 on the body whorl; spiral cords somewhat indistinct on the shoulder and narrower near the columella. Aperture ovate, columella incurved, columellar callus thin, parietal callus not thick enough to obliterate the sculpture, the anterior end of the columella consisting of a curved fold; two oblique folds higher on the columella, the posteriormost the largest, the folds hardly showing on apertural view, but much stronger within (shell viewed obliquely). Outer lip thin, Urate within. Operculum lacking.
Dimensions: height 61.3 mm, diameter 31.5 mm (holotype); height 62.9 mm, diameter 31.0 mm (paratype); height 57.5 mm, diameter 30.8 mm (paratype).

Cancellaria stuardoi: A species of the subgenus Crawfordina characterized by its large size, high spire, convex whorls, and sharp clathratc sculpture. It is remarkably similar to the type species of Crawfordina, C. Crawfordiana from California. The latter species has a more fibrous periostracum, is somewhat more slender and smaller (attaining a length of about 50 mm), has a slightly more constricted tip to the canal, and has fine pustules on the anterior region of the columellar callus. Despite these differences, the two species are clearly related, having similar proportions, sculpture, and the columellar plications visible in oblique view. Cancellaria io. the third member of the subgenus, differs from both C stuardoi and C crawfordiana in having subdued spiral sculpture.

Cancellaria stuardoi: TYPE LOCALITY. 240-350 m off Pichilemu, Chile (34°27'S, 72°24'W).
DISTRIBUTION. Coquimbo (29°58'S), to Pichilemu (34°27'S), Chile. Depth range: 200-350 m.