Prothalotia flindersi, common name the Flinders top shell, is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
The height of the shell attains 16 mm, its diameter 13 mm. The rather thick, very narrowly perforate shell has a conical shape. It contains 7 to 8 planulate whorls. The first one is eroded, the succeeding are whitish-ashen, radiated with narrow, close and flexuose blackish and violaceous lines. They are spirally cingulate, with 6 lirae on penultimate whorl. The body whorl is subangular, a little depressed above, dilated in the middle. The base of the shell is convex and ornamented with about 8 lirae. The aperture is rhomboidal. The lip is simple. The truncate columella is truncate below.
This marine species is endemic to Australia and occurs off South Australia and Western Australia.