Abstract
One of the inversions in Chironomus (Kiefferulus) intertinctus Skuse, the Corio inversion in chromosone III, is closely linked to the sex-determining region. Different selective values in males and females result in the Standard sequence being more common in the Y -chromosomes while the Corio sequence is more common in the X-chromosomes. In a population from Echuca, Vic., only the Standard sequence occurs in the Y-chromosomes.