Family Solecurtidae

Shell size to 70 mm; shell light, strong, elongate, rectangular. Sculpture absent except for fine concentric lines. Umbones central. Weak radial ridge present posteriorly. Periostracum olive-brown. Common in muddy areas at low tide.

Shell size to 40 mm; shell light, thin, elongate, rectangular. Sculpture absent except for fine concentric lines. Umbones posterior. Radial ridge present internally. Periostracum thin, light-brown. Color purplish with rays of stronger purple. Common in muddy areas at low tide.

Shell to 48 mm, trapezoidal or rectangular in shape, twice as long as tall. Sculpture of commarginal ("concentric") growth lines crossed by more widely separated oblique lines. Shell inflated, with wide gapes at anterior and posterior ends. Shell whitish, sometimes with remnants of yellowish-brown periostracum present. Kimberly J. Nealon found the valve here illustrated on Captiva, on May 21, 2016.