“…It seems clear that at least two other families of Acalyptrate Diptera have achieved a high degree of stability at the 2n = 12 chromosome number level whereas families such as the Drosophilidae, Otitidae and Platystomatidae have less stable chromosome numbers with a marked tendency toward reduced numbers. Since the great majority of the Calyptrate Diptera have 2n ~--12 chromosomes (BOYES 1953(BOYES , 1954(BOYES , 1961(BOYES , 1963(BOYES , 1964a(BOYES , 1964b(BOYES , 1967BOYES& WILKES 1953;BOLES, COREY• PATERSON, 1964, BOYES t~ VAN BRINK, 1965 it is perhaps permissible to suggest that the Sciomyzidae and Tephritidae may be closer to the main line of evolutionary origin of Calyptrate Diptera than are such families as the Otitidae, Platystomatidae and Drosophilidae. Also it is rapidly becoming clear that a 2n ~-12 karyotype having a short telocentric and heteromorphic sex pair, together with five meta-to submetacentric autosomal pairs, is a common karyological feature of the Acalyptrate and Calyptrate Diptera and could be the basic (primitive) karyotype in such Diptera.…”