Shape elliptic with convex medial face and concave lateral face. Dorsal depression shallow, fan-shaped. Dorsal margin approximately entire and ventral margin serrate. Sulcus ostial, deep. Ostium oblong and cauda tube-like, flexed ventrally. Colliculum low, flat in ostium and cauda. Crista superior and crista inferior well-developed, both absent at posterior. Neck slightly constricted. Rostrum triangular, large. Excisura moderate. Notch absent.