The hierarchy of
biological classification's
eight major taxonomic ranks,
which is an example of
definition by genus and differentia.
Intermediate minor
rankings are not shown.
This diagram implies
3 Domains / 6 Kingdoms
(Woese et al. 1990[1]):

  1. ^ Carl R. Woese, Otto Kandler, Mark L. Wheelis: "Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya". Proceedings of the National Academy of Sciences of the United States of America, 87(12):4576-9. doi:10.1073/pnas.87.12.4576