: Up to five inches. Shape:
Elliptical or ovate; L:H ratio usually less than 1.5. Valves laterally inflated but this trait is variable. Valves slightly to moderately compressed toward the posterior dorsal margin, broad, and raised to form a “wing”. The prominence of the wing is variable. Valves are thin and fragile. Beaks Small; scarcely elevated above the hinge line. Periostracum
: Color is variable, with individuals appearing yellowish-green, yellowish-brown, olive, pale brown, reddish brown, or black. There are greenish rays on the posterior slope. The periostracum is smooth and growth lines are prominent. Hinge Teeth
: None. Nacre:
Usually white, but sometimes with a flesh-colored, purplish, or bluish tint.
For a discussion on Anodonta
taxomony, please refer to the original publication, The Freshwater Mussels of the Pacific Northwest.