Ovate with convex medial face and concave lateral face. Dorsal margin and ventral margin entire, notched posteriorly. Sulcus ostial, deep. Ostium oval and cauda elongate, flexed. Colliculum raised at ostium. Crista superior well-developed. Crista inferior poorly-developed along ostium and well-developed along cauda. Neck ventrally constricted. Rostrum triangular. Excisura wide. Notch deep.