As the ducts of Cuvier come from each side the sinus spreads out to meet them and becomes transversely elongated.

Shell transversely oblong, thick, depressed, within purple; hinge plate thick, truncate, with an obsolete lamellar tooth in each valve; umbones retuse.

Bill very large, longer than the head, thick, light, curved, and thickened at the basal margin; the frontal angle transversely sub-truncated, margins serrated.