Shell medium in size, about 30 mm. in length, depressed conical. Ante¬rior slope straight, posterior slope convex. Base oblong-ovate. Apex directed forward, situated at the beginning of the second third and pierced by the orifice. The orifice has the same shape as the basal margin and is slightly contracted in the middle, its length being from one-eighth to one-tenth that of the shell. The surface is sculptured with nu¬merous close-set. rather sharp, radiating ridges which are closely decussated throughout with concentric striae. Shell is alternately rayed in buff and a greenish brown. The orifice is always outlined by a line black line. Margin of shell thin, very sharply crenulated. Inside color grayish white. Internal callus of the orifice thick and outlined by an indenture. It has the same color as the rest of the inside and is surrounded by a dark gray streak. Muscle scar deeply impressed.

D. patagonica is a fairly abundant species from Trinidad south along the east coast of South America. It is not found in the rest of the West Indies. D. metcalfii (= synonym of D. patagonica) Reeve has been constantly considered a synonym of D. cayenensis, but the specimens that we have seen agree exactly with Reeve's figure and description. These in turn agree with d'Orbigny's. This species is related to D. cayenensis , but the obvious differences in the sculpture, the shape of the orifice and the basal margin make it impossible to confuse them.

Trinidad south through Brasil to Argentina.