Theliderma cylindrica shell description:

 “Shell much elongate; inflated and having parallel dorsal and ventral lines so that it is almost cylindrical, inequilateral, solid; beaks rather full and elevated, turned forward over a deep, wide lunule, their sculpture a few irregular, strong ridges that are nodulous on the posterior ridge; posterior ridge full, rounded; above it there is usually a wide, radial impression that sometimes ends in a slight sinus behind; anterior end rounded, subangular above; posterior end squarely or obliquely truncate; sometimes there is a point behind below the median line; surface with irregular, concentric sculpture, having a row of knobs extending along the posterior ridge and often more or less covered with lachrymous nodules and plications; epidermis straw-color, tawny, yellowish-green or greenish-yellow, generally overlaid with a pattern of triangular, green blotches, these are sometimes developed into radial stripes as if they had been painted on and had drizzled down; sometimes the green blotches are so close that they are only separated by narrow, greenish-yellow, zigzag lines, the whole smooth and somewhat shining; Pseudocardinals radially split up; laterals long and straight; anterior scars impressed; beak cavities deep, compressed; nacre silvery white, rarely purplish, iridescent and much thinner behind”(Simpson, 1914; Mather, 2007).