Shape ovate with convex medial face and concave lateral face. Dorsal depression deep, fan-shaped. Dorsal margin dentate, irregular and ventral margin creanate, lobed. Sulcus ostial, deep. Ostium flared and cauda elongate, markedly flexed ventrally at posterior. Colliculum higher in cauda, bulbous dorsally and extended over excisura in ostium. Crista superior and crista inferior well-developed. Rostrum extended, large, downward. Excisura wide. Notch deep, interrupted.