joint nature.-the correspondence of common descent; -- a term used to supersede homology by lankester, who also used homoplasy to denote any superinduced correspondence of position and structure in parts embryonically distinct (other writers using the term homoplasmy). thus, there is homogeny between the fore limb of a mammal and the wing of a bird; but the right and left ventricles of the heart in both are only in homoplasy with each other, these having arisen independently since the divergence of both groups from a univentricular ancestor.