Originally described as Pyrina parryi by Hall in Conrad (1857).
Original description (p. 144; source here):
"Shell oblong ovoid, or somewhat pentagonal, with the angles rounded, convex above and concave in the middle beneath; apex central, flat or slightly depressed, prominently convex in front, and subtruncate behind; mouth central, oval; anus ovate, narrower above and situated centrally between the upper and lower side of the shell ; ambulacral areas somewhat prominent or slightly elevated above the rest of the surface. Tubercles on the upper side scattered, with granular spaces between, becoming more numerous on the sides and crowded on the base of the shell. Length 1 1/4 inches ; width 1 1/8 inches."