Shape approximately triangular with pointed dorsal angle in the middle of dorsal margin. Convex medial face and concave lateral face. Dorsal depression shallow. Dorsal margin entire and ventral margin slightly serrate. Sulcus ostial, deep. Ostium triangular, downward and cauda elongate, slightly flexed ventrally at posterior. Colliculum large in ostium. Crista superior and crista inferior well-developed, both absent at posterior. Neck slightly constricted. Rostrum triangular, downward. Excisura wide. Notch shallow.