THE NYMPH OF THE MAYFLY GENUS CINYGMA EATON

In early June of the summer of 1928 an immature nymph of the genus Cinygma was dredged from tlie sedges along the edge of a mill pond at Horning's Mills, Ontario. All attempts to get more material here were unsuccessful. Next year, however, on June 7, I met with some full-grown nymphs in a deep rock-pool by the edge of a stream which flows into Lake Nipissing, Ontario from the south. About fifteen individuals were reared between the 10th and the 20th of June and the species proved to be Cinygma bipunctata McD. The description of the type fits these individuals very well.