THE first mutation reported in the Syrian hamster, Mesocricetus auratus, was a recessive type of white spotting which has been designated as piebald1. The new mutation to be described here differs from piebald in two respects : (1) the mutation is inherited as a dominant to normal pigmentation ; and (2) the characteristic spotting pattern produced by the mutation is phenotypically distinguishable. The new mutant gene has been termed ‘white band’ and has been given the symbol Ba. The gene was discovered in the United States in 1957, and stock carrying the gene was imported into Britain during 1959.