Shape oblong to ovate with convex medial face and concave lateral face. Dorsal margin approximately entire and ventral mar gin notched, crenate. Sulcus ostial, deep. Ostium oblong, bended downward and cauda elongate, flexed ventrally at posterior. Colliculum low and large in ostium. Crista superior and crista inferior well-developed. Neck dorso-ventrally constricted. Rostrum rounded, large. Excisura wide. Notch shallow.