Shape elliptic with convex medial face and concave lateral face. Dorsal depression grooved, fan-shaped. Dorsal margin and ventral margin largely serrate, notched, lobed. Sulcus ostial. Ostium flared and cauda elongate, slightly flexed ventrally at posterior tip. Colliculum low. Crista superior ridge-like and crista inferior well-developed, both absent at extremes. Neck dorso-ventrally constricted. Rostrum extended, pointed. Excisura moderate. Notch deep.