Abstract: | This paper comments on recently revived discussion about the most adequate definition of homology. Homologues are considered as similarities of complex structures or patterns which are based on a continuity of biological information or instruction. Dependent on the level of comparison four types of homology are defined: (1) Iterative ( = serial = homonomy), (2) ontogenetic, (3) di- or polymorphic, and (4) supraspecific homology. The significance of all four types for evolutionary biology and phylogenetic analysis is outlined. |