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).
Lankester (Homoplasy and Homogeny), " On the Use of the term Homology in Modern Zoology," Ann.
The most fundamental distinction in analysis is that which must be made between homogeny, or true hereditary resemblance, and those multiple forms of adaptive resemblance which are variously known as cases of " analogy," " parallelism," " convergence " and " homoplasy."
Of these two kinds of genetic and adaptive resemblance, homogeny is the warp composed of the vertical, hereditary strands, which connect animals with their ancestors and their successors, while analogy is the woof, composed of the horizontal strands which tie animals together by their superficial resemblances.
Homogeny, in contrast, the " special homology " of Owen, is the supreme test of kinship or of hereditary relationship, and thus the basis of all sound reasoning in phylogeny.
One point must not be omitted, namely, the homogeny of the endostyle of Amphioxus and the thyroid gland of Craniata.