Lasmigona costata shell description:

 “Shell long rhomboid, subcompressed, solid, inequilateral, with scarcely elevated, compressed beaks, their sculpture consisting of a few strong, straight or slightly double-looped ridges; posterior ridge well developed, sometimes partly double; posterior slope covered with strong, corrugated, radial costations; hinder half of the disk often slightly corrugated; growth lines strong and irregular; epidermis yellowish-green, tawny or brownish, often rayed, dull or subshining; left valve with a strong ^-shaped reflexed tooth under the beak, often with a low one in front of it; right valve with an irregular, subtriangular tooth in front of the beak, the hinge plate cut away behind it; laterals low and much blurred; muscle scars large, impressed, the anterior ones separate; nacre whitish or straw-colored” (Simpson 1914, Mather 2007).