Shell adhering, irregular, thick, pearly, inequivalve, inequilateral; summits thick, little evident; hinge toothless, callous, thick, irregular; longitudinal, sub-dorsal ligament, partly exterior and partly penetrating into the shell; two oblong muscular impressions, one inferior and anterior, the other superior and sub-posterior; with or without an oblong incrusted callosity on the base of the valve.
Etheria elliptica.
E. semilunata.
E. trigonula.
E. transversa.
E. elliptica. The oval Etheria. Pl. [11], fig. 1.
Species with an oblong callosity on the anterior part of the shell; oval, depressed, dilated towards the umbones; summits distant.
E. semilunata. The semilunar Etheria.
Species without callosity at the base.