Shape oblong with flat medial face and flat lateral face. Dorsal margin and ventral margin slightly crenate, lobed. Sulcus ostial, deep. Ostium flared, oblong and cauda elongate, flexed ventrally at posterior. Colliculum low, large in ostium and extended over excisura. Pseudocolliculum above posterior cauda. Crista superior poorly-developed and crista inferior well-developed, poorly-developed along ostium.