This genus covers shells with a circular outline, a conical spire with a central nucleus and a moderate sigmoid outline to the edge of the septum. The shape and central position of the nucleus recall both the English Calyptraea sinensis Linn, and the New Zealand genus Zegalerus. The former, however, has a more elaborate septum which terminates as a tongue forming both a spiral umbilicus and a deep sinus at its outer extremity. In Zegalerus the septum is gently concave to almost straight. A second Austro-neozelanic genus, Sigapatella, has a simple arcuate septum as in Zegalerus, but the shell has more rapidly increasing whorls with the apex off centre