Abstract
The third chromosome arrangements of northern populations of Drosophila persimilis were reexamined for comparison with their frequencies four decades ago. A total of nine arrangements were found to occur, including four new arrangements. Photographs of all of the arrangements are provided, includig homokaryotypes and the most informative of the heterokaryotypes. The frequencies of the most common arrangements have remained relatively constant over the 40-year span since the only previous analysis. The only changes are a slight decrease in the frequency of the Klamath arrangement, with an increase in the frequencies of the rare arrangements.