1. Fitch, W. M., Margoliash, E.: Biochem. Genet.1, 65 (1967).
2. —, Markowitz, E.: Biochem. Genet.4, 579 (1970).
3. Holmquist, W. R.: J. molec. Evolution (in press) (1971a, b).
4. - Cantor, C. R., Jukes, T. H.: Submitted to J. molec. Biol. (1971).
5. Ingram, V. M.: The hemoglobins in genetics and evolution. New York: Columbia University Press 1963.