Ray Lankester's term, homoplasy, has passed into currency as designating such cases where different genetic material has been pressed by similar conditions into similar moulds.
The probability is against agreement being due to homoplasy when the agreement involves a number of really separate (not correlated) coincidences.
Homoplasy can only be assumed when the coincidence is of a simple nature, and is such as may be reasonably supposed to have arisen by the action of like selective conditions upon like material in two separate lines of descent.'
Lankester (Homoplasy and Homogeny), " On the Use of the term Homology in Modern Zoology," Ann.
The resemblances which the members of one class often present to the members of another class in regard to the form of the limb-branches (rami) of the parapodia, and the formation of tagmata (regions) are not hastily to be ascribed to common inheritance, but we must consider whether they are not due to homoplasy - that is, to the moulding of natural selection acting in the different classes upon fairly similar elements under like exigencies.
Secondly, identity of structure in two organisms does not necessarily indicate that the identical structure has been inherited from an ancestor common to the two organisms compared (homogeny), but may be due to independent development of a like structure in two different lines of descent (homoplasy).