Notocallista disrupta
The overall shape is trigonal, ovate. The posterior margin is lightly pointed, and the anterior and ventral margins are rounded. There may be a slight sinuosity of the ventral margin at the posterior. The anterior dorsal margin is subconcave, and the posterior dorsal margin is subconvex. The valves are equal in size and shape (equivalve), and there is no gape when they are closed. Sculpture consists of growth lines and concentric grooves that result in the formation of wide, rounded comarginal ribs. The lunule is lightly impressed and tear-drop shaped; it extends half the anterior dorsal margin and is defined by a fine, shallow groove. The umbones are prominent and subanterior, and the beaks also point slightly to the anterior. The escutcheon is not well defined.
The exterior is cream with overlaid light brown tent marks and/or zig-zag patterns forming radial stripes. There may also be faint purple coloration along the grooves. The interior is white with faint purple coloration in the umbonal cavity, descending toward the ventral margin. There may also be purple coloration along some of the growth lines.
The ligament is external, extends 1/3 of the posterior dorsal margin and is supported by nymphal ridges. The nymphs have a granulose texture. On the left valve, there are three cardinal teeth, none of which are bifid. The anterior (2a) and central (2b) teeth are joined dorsally, forming an inverted "v" shape. The posterior tooth (4b) is fused with the nymph. There is also one anterior lateral tooth (A2) on the left valve. On the right valve, there are three cardinal teeth: the anterior (3a) and central (1) teeth are not bifid, and the posterior tooth (3b) is bifid. There are two anterior lateral teeth (A1, A3) on the right valve, as well as a fine, weak ridge that runs parallel to the posterior dorsal margin. The anterior and posterior adductor muscle scars are similar in size and shape. The pallial sinus extends to the middle of the nymph in length and its deepest point forms an acute angle.