Subfamily Chelonibiinae Pilsbry, 1916: 262

Type genus. Chelonibia Leach, 1817:68; by original designation of Pilsbry (1916: 262).

Diagnosis. Wall eight-plated (R-RL-CL1-CL2-C), bilamellar, with internal, longitudinal canals; parietal space between (primary, secondary and tertiary) laminae filled with longitudinal septa, spaces between which may be partially to almost completely filled; without external T-shaped flanges and canals.

Genus and species included. † Chelonibia capellini de Alessandri, 1895; Chelonibia caretta (Spengler, 1790); Chelonibia dentata Henry, 1943; † Chelonibia depressa Seguenza, 1876; † Chelonibia hemisphaerica Rothpletz & Simonelli, 1890; Chelonibia manati Gruvel, 1903; Chelonibia manati crenatibasis Pilsbry, 1916; Chelonibia manati lobatibasis Pilsbry, 1916; † Chelonibia melleni Zullo, 1982; Chelonibia patula (Ranzani, 1818); Chelonibia patula dentata Henry, 1943; Chelonibia ramosa Korschelt, 1933; Chelonibia testudinaria (Linnaeus, 1758); † Chelonibia testudinaria var. solida Withers, 1929 .