Torotaia Haas, 1939

Examined species: Torotaia mainitensis (Bartsch, 1907) (Figs 4F, 5F, 7F).

Remarks: The operculum of Torotaia is distinct from that of most genera, but similar to that of Celetaia in the following characters: a large, smooth and shiny nuclear region, which is sometimes surrounded by concentric veins, and a thin marginal region. However, the operculum of Torotaia is more fragile and thinner, with the apex being noticeably more acute than in Celetaia .