Arcidens wheeleri shell description:

 "Male and female shells alike.  Shell subrotund to subovate or subrhomboidal, inflated, rather thick and solid; dark reddish-brown or black, usually lighter toward the beaks, which in young shells are chestnut-colored; epidermis with a silky luster; beaks very prominent, projecting anteriorly and incurved over the large lunule, their sculpture consisting of two or three double-looped bars, the loops slightly swollen or tubercular; sculpture restricted to the extremity of the beaks, the remainder of the umbonal region being entirely smooth; posterior half of the disk sculptured with irregular, oblique folds, sometimes nearly obsolete, which on the dorsal slope curve upwards, and in front of the posterior ridge are crossed by numerous, irregular, radiating, small folds or wrinkles at right angles to the lines of growth; anterior portion of the disk smooth; anterior margin nearly straight in front of the beaks, then projecting in a regular curve, which continues around the basal margin until it meets the posterior margin at an obtuse angle about one-third up from the base; Hinge margin nearly straight; posterior margin slightly curved; posterior ridge not prominent, usually rounded, but sometimes obscurely biangulate; hinge complete; pseudocardinals strong, ragged, in the left valve, two, not strongly differentiated and coalescing along the hinge line, the anterior narrow and parallel with the hinge line, the posterior somewhat wider and heavier and scarcely separated from a strong projection of the interdentum, which is continuous with the lower lateral and slopes gradually to its extremity; upper lateral low, the groove between them deep and extending nearly to the beak; a single, strong pseudocardinal in the right valve with a deep pit behind it to receive the anterior pseudocardinal of the left valve, interdentum cut away to make room for the interdental projection in the left valve; a single strong, but rather short lateral; ligament dark brown; muscle scars not very deep, those of the anterior adductor and posterior adductor large, those of the anterior retractor and pedal protractor rather small and inconspicuous; Cavity of the beaks very deep; nacre usually salmon-colored above the pallial line, bluish-white below (sometimes entirely white) and rather thin, slightly iridescent with a wide, dark prismatic border (Mather, 2007)"