Shells large, aduliform, long and slender, rather thick, solid. Ventral margin markedly concave in adults, giving the shell a curved appearance. Umbonal cavity large and swollen. Periostracum strong chocolate or dark brown, umbonal region light brown; valves dull white beneath the periostracum. Inner mantle folds entirely separate, terminating anteriorly on anterior adductor. No valvular siphonal membrane. Anterior retractor scar situated in front of umbonal cavity; posterior byssus retractor complex with two principle diverging muscle bundles.
HASHIMOTO J. & M. HORIKOSHI (1989) Deep-Sea Newsletter 15: 32-34.