Shape elliptic with notched posterior margin and dorsal depression. Dorsal margin and ventral margin entire. Sulcus ostial, deep. Ostium flared, oval and cauda elongate, flexing ventrally. Colliculum raised under posterior cauda. Crista superior ridge-like only above straight part of cauda, absent elsewhere. Crista inferior well-developed. Neck dorso-ventrally constricted. Rostrum thick, blunt and antirostrum rounded. Excisura wide.