homologous organs

Their scales, called dermal denticles, and teeth are homologous organs.

In both sexes the gonad goes on to form the testes and ovaries, because they are derived from the same undeveloped structure they are considered homologous organs.

The opposite of homologous organs are analogous organs which do similar jobs in two taxa that were not present in the last common ancestor but rather evolved separately.

The mouthparts of different insect groups consist of a set of homologous organs, specialised to the function of dietary intake of that insect group (which can be experimentally quantified).

He also worked on more general questions of comparative anatomy and zoology, and summarized this work in the book Oligomerization of Homologous Organs (1954) which he presented his new theory of the evolution of the Metazoa.