Large, ovate-cylindrical, length up to 110 mm, sub-elliptical, very elongate, fragile, moderately gaped at both ends; anterior and posterior ends rounded ,umbos well developed, sub central, placed on the anterior fourth of the valves; umbonal reflection double, the inferior one free at the anterior side of the umbos, the upper reflection septated ,umbonal reflection usually eroded at the contact point with the complement valve;external surface with radial ribs almost covering the entire shell, only absent in the anterior part; concentric sculpture well defined, strong on the anterior slope, but weaker near the umbo; imbricated scales are observed where the radial ribs cross the concentric ridges ;internally white; external sculpture usually visible from inside the shell.