Sunetta vaginalis
The overall shape is ovate. The anterior dorsal margin is very slightly concave; the rest of the margin is rounded. The valves are similar in size and shape (equivalve), except the lip of the ventral margin may be slightly wider on the right valve. There is no gape when the valves are closed. The posterior half of the flank is slightly more inflated than the anterior. Sculpture consists of growth lines only. The lunule is lightly impressed, defined by a fine shallow groove and extends half the anterior dorsal margin. The umbones point slightly to the anterior. The escutcheon is very deeply sunken.
The exterior of the flank is white with light tan or slightly pink comarginal stripes, radial stripes and/or tent marks. The coloration may deepen as the animal grows. The lunule may be dark brown or dark pink, and the escutcheon may have brown stripes. The interior color is white with pink coloration in the umbonal cavity, extending to the middle of the interior. The pink coloration may also be concentrated in the pallial sinus.
The ligament is external, extends 1/3 of the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth. The teeth (2a, 2b, 4b) are not bifid, the anterior tooth (2a) is weak, and the posterior tooth (4b) is merged 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 tooth (3a) is weak and not bifid, the central (1) tooth is not bifid, and the posterior tooth (3b) is fused with the nymph. There are also two anterior lateral teeth (A1, A3) on the right valve. There are crenulations on the posterior ventral and ventral margins, and they become weaker at the anterior. The adductor muscle scars are similar in area, but the posterior is rounder than the anterior. The pallial sinus is rounded and extends to the posterior end of the nymph in length.