The ventral margin is slightly concave. The dorsal margin is distinctly convex, often with two shallow undulations. The valve is somewhat narrower at the ends than at the center. The apices of the valve are rounded, somewhat narrower but not distinctly set off from the main body of the valve. The terminal nodules are near, but not at the ends of the valve, distinct but not large. The striae are straight, almost perpendicular to the ventral margin at the center of the valve, but somewhat curved at the ends(Patrick and Reimer 1966).