The Dragon-flies (Odonata) of Illinois, with Descriptions of the Immature Stages.

The present paper is the combined product of studies made by the authors upon the collections of the Illinois State Laboratory of Natural History, including those of the Biological Station at Havana, and by Professor Needham on his private collection. The state collections comprise the results of many years' work in all parts of Illinois, including five successive years of field observation and collection at the Illinois Biological Station on the Illinois Eiver at Havana ; specimens ol)- tained by Professor H. Garman from the Mississippi and related waters at Quincy, 111. (Garman, '90); a large series from the small lakes of northeastern Illinois ; and collections made by Professor Forbes in Yellowstone Park and its vicinity (Forbes, '93) and from lakes Geneva and Delavan, Wis., under the auspices of the IT. S. Fish Commission. Professor Needhaui's private collection used in the preparation of this paper contains many Illinois and New York species, reared by him to the imago, and others contributed by correspondents, particularly by Mr. F. G. Schaupp in Texas, Mr. Adolph Hempel in Florida, and Mr. F. C. Willard in Arizona. The preparation of the introductory matter, biological discussions, and keys to the nymphs has devolved upon Mr. Hart, while the descriptive matter, with a few exceptions, was prepared by Professor Needham.Ope