Noetia (=Arca) centrota (Guppy, 1867) (= martini)

The Noetia centrota is up to 4 cm in length. It is  equivalve, inequilateral (it beaks in anterior half), thick, oblong in shape, rounded anteriorly and elongated posteriorly. The posterior end is much longer than in the other species and bears two radial ridges (which can be seen slightly indented, thus assuming on ear-like appearance). The beaks are fairly close together. It is white, light brown, or grey in color and is sometimes banded. The Interior of shell is whitish (but usually depends on the external coloring). It is sculptured by 32-35 finely beaded ribs (cf. Andara ovalis) with smaller riblets (also finely beaded) in the grooves between them (one per groove). Heavily marked growth rings can be seen in some specimens of this species. It has 28-36 hinge teeth, the larger specimens usually having more. The periostracum is thick, hairy, and reddish brown in color. This shell is not quite as common as the other two species.