Shape elliptic with raised angle in the middle of dorsal margin. Convex medial face and concave lateral face. Dorsal depression shallow, fan-shaped. Dorsal margin and ventral margin dentate, irregular. Sulcus ostial, deep. Ostium triangular, slightly emarginated ventrally and slightly bended downward. Cauda elongate, flexed ventrally at posterior. Colliculum low, large in ostium and extended over excisura. Crista superior and Crista inferior well-developed. Rostrum blunt, rounded. Excisura moderate. Notch absent.