Family Periplomatidae

Shell size to 17 mm; shell oval, thin, truncate posteriorly, with posterior keel that runs from beak to ventro-posterior region of valve. Region posterior to keel usually with thicker periostracum, darker. Valves unequal, left valve more inflated, larger than and overlapping right valve. Color white to translucent-white. Shell collected in shallow-water at Roosevelt Channel, Captiva Island, by Alice and Ken Piech. The shell in the supplementary images was collected by Susan Hewitt at Bowditch Point, Fort Myers Beach, in December 2017. The shell is about 10 mm, or about 0.39 inch