Kidney-shaped, large. Dorsal margin digitate, especially posterior part. Ventral margin approximately entire. Sulcus ostial, deep, oval. Ostium and cauda separated by colliculum and form two opposite triangular. Colliculum raised, solid bridge. Crista superior and crista inferior well-developed. Neck constriction not observed. Rostrum thick, rectangular and facing upward. Antirostrum rounded and small. Excisura narrow facing upward. Notch deep.