The following list of Odonata is mainly the result of four seasons collecting in various parts of Ontario, but chiefly in three localities, viz: Toronto, De Grassi Point, Lake Simcoe, and Algonquin Park.

Although most of the material was collected by the writer, the list has been considerably lengthened by the records of captures made by other collectors. Among these should be mentioned the collections of Dr. Wm. Brodie, in the Educational Dept., Toronto; many specimens taken in Algonquin Park by Prof. Macoun in 1900, and by Mr. Paul Hahn in 1903–4; a considerable number from the collection of the Biological Dept. of the University of Toronto, consisting chiefly of alcholic specimens of nymphs and imagoes taken at the Biological Experiment Station at Go Home, Georgian Baym and a few collected and presented to the Department by the late Mr. R. T. Anderson; and finally, a small collection from Thessalon, Algoma, belonging to Miss Rounthwaite, of Toronto.