Shell 23 mm. in width, thin, depressed turbinate and opalescent. Whorls 7, strongly convex. Color old ivory with an opalescent sheen on all portions of the shell. Early whorls often a vivid wine-color. Aperture subelliptical. Umbilicus deep and fairly wide, the whorls within visible and slightly inset. Columellar callus or pad nearly cover¬ing the umbilical opening. Outer lip slightly thickened and reflexed. Spire somewhat depressed. Suture distinct and impressed. Nuclear whorls smooth. Spiral sculpture of minute incised lines, scarcely apparent on early whorls, fairly strong on later whorls. Axial sculpture of very fine growth lines. Periostracum absent. Operculum unknown. Height 13-13,5 mm; width 22.5 – 23 mm.

Clench & Abbott (1943) suggested that this form is specifically distinct from G. superba (Dall), but Abbott (1974) indicated that he considered it to be an infra-subspecific form of superba. I have not, as yet, been able to examine enough specimens of either species to enable me to resolve the problem. The few specimens I have seen and an examination of the ranges of the 2 forms indicates to me at least a separation at the subspecific level, and pending further research, I am leaving cubana as a subspecies of superba. G. superba differs from cubana in being larger, more inflated, and higher-spired. G. superba occurs throughout the Caribbean area and extends up into the northern Gulf of Mexico, while cubana is restricted to the Straits of Florida and the Yucatan Channel as far as is now known. G. superba cubana also seems to prefer the insular margin of the Straits, but occurs along the continental coast of southeastern Yucatan.