Cyprogenia aberti shell description:

 “Shell of medium size, seldom exceeding 80mm in length.  Outline usually rhomboidal, occasionally rounded triangular.  Valves slightly inflated, thick and heavy.  Anterior end regularly rounded;  posterior end subtruncate.  Ventral margin more or less rounded, tending to be straight or slightly concave posteriorly.  Dorsal margin slightly convex forming a more or less distinct angle with the almost vertical, sometimes concave, posterior margin.  Hinge ligament rather long.  Posterior ridge well developed, high and narrow at the umbonal region, becoming flattened and somewhat double, with a wide shallow groove before it.  Posterior slope with a radial furrow, very narrow.  Umbos low and compressed, curved forward over the lunule, located at the middle of the shell or somewhat anteriorly.  Surface of the shell with strong, low, more or less numerous, concentric ridges; in addition it is sometimes subvertically wrinkled and nodulous.  Periostracum scarcely shining, yellowish green, with dots and flecks of dark green which fall into broad broken rays.  Hinge very broad and flat.  Left valve with two heavy, triangular, blunt and ragged, pseudocardinal teeth of about equal height;  also with two short, very low lateral teeth. Right valve with one large pseudocardinal, sometimes with a feeble one on each side of it.  Interdentum is very broad.  One low double or triple lateral tooth.  Umbonal cavities are very shallow and compressed.  Anterior and posterior adductor muscle scars and pallial line are all well impressed.  Nacre is white, thinner and somewhat iridescent anteriorly ”(Mather, 2007).