The umbones, or hinge teeth, of the shell are located at about the middle of the valves. The outer surface of the shell is decorated with irregular, circular, wavy ridges. There is one anterior and one posterior cardinal tooth in each valve. The anterior adductor muscle scar is elongated, while the posterior adductor muscle scar is roughly square and has a distinct, tooth-like expansion at the bottom. The pallial sinus is very deep, and the shell margins are indented.