A–C Cymatioa cooki, shell of left valve collected at Naples Point, SBMNH 641848, length 8.8 mm A exterior of valve B interior of valve C close up of hinge D–F Cymatioa electilis, left valve D, E holotype, CASIZG 043976, length = 16 mm D exterior of valve E interior of valve F paratype, SBMNH 34017, close up of hinge.