Theliderma metanevra shell description:

“Shell irregularly rhomboid, more or less inflated, solid, inequilateral; beaks rather full and high, turned forward over a narrow lunule, their sculpture a few strong, irregular ridges, which are nodulous on the posterior ridge; posterior ridge elevated, rounded, separated from the rest of the shell in front and behind by a radial depression; anterior end rounded; base line straight or incurved behind the middle; dorsal slope obliquely truncated, the sulcation above the posterior ridge ending in a well-marked sinus; surface more or less covered with lachrymose knobs or tubercles, a row on the posterior ridge usually higher; epidermis yellow-green, tawny or brownish, often marked with small, dark green, triangular patches subshining to dull and rough; pseudocardinals ragged, two in the left valve and three in the right; laterals short; anterior scars small, impressed; beak cavities deep, compressed; nacre white, rarely pinkish, greatly thickened at the anterior base ”(Simpson, 1914; Mather, 2007).