Yellow Top Shell. Shell depressed-turbinate, broadly perforate, translucent, glossy; colour variable, either uniform buff, uniform white, or brown spirals on a white ground. Whorls four and a half, rounded on the base subangled at the periphery, flattened above and impressed at the suture; protoconch smooth, the next whorl with two spiral keels, which by intercalation multiply in number, but decrease in relative importance as the whorls advance, the last whorl carrying close fine spiral threads, of which every fourth or fifth predominates; the radials are confined to faint growth lines; aperture slightly descending, oblique, angled above, rounded below; outer lip simple; columella expanded, and a little reflected above, a substantial callus unites the lips; umbilicus deep, narrow, spiral, externally funicular, exempt from the spiral sculpture. Diameter 7 mm., height 5.5 mm.

The species is nearest to Nanula flindersi Cotton and Godfrey, of which it may be the deep water subspecies. N. galbina is thinner, larger, proportionately lower and broader, and more widely umbilicated. A single specimen was taken by the "Thetis" in 63-75 fathoms off Port Kembla, but was catalogued as Gibbula tasmanica Petterd.