DEC ?0 1896 

 10 



11 



Article VI. — On the Entomology of the Illinois River and 

 Adjacent Waters. First Paper. By C. A. Hart. 



INTRODUCTORY. 



This paper gives a part of the results of our observa- 

 vation and study of the insect fauna of the Illinois River 

 and adjoining waters in the neighborhood of the Uni- 

 versity of Illinois Biological Experiment Station, at 

 Havana, Illinois, during the first year of the Station 

 work, as a preparation for further and more detailed 

 •observations in the same field. In order to make the 

 account more complete and useful to Illinois students, 

 and to give a general view of the relations of the species 

 studied to the aquatic fauna of the State as a whole, 

 the data concerning these forms afforded by the note 

 boxes and general collections of the State Laboratory 

 of Natural History are also here included. 



Distinctive characters, when known to me, are tabu- 

 lated in the form of keys. These are necessarily imper- 

 fect because of the small number of immature forms 

 now known, the difficulty of determining the true rank 

 of the differences observed, and the frequent impossibility 

 of harmonizing the grouping with the present classifica- 

 tion of the imagos. I hope, however, that they may 

 prove useful, and suggestive in further studies. It is 

 evident that a knowledge of all stages is necessary to 

 the formation of the best natural classification. 



Special thanks are due to Prof. S. A. Forbes, who 

 originated the Station and has planned and directed its 

 work; and to Messrs. C. H. Fernald, W. H. Ashmead, and 

 W. A. Snow for determinations. I am also under bbliga- 

 tions to my fellow-workers at the Station for their 

 kindly cooperation, and to Miss Lj'dia Moore Hart for 

 the accurate drawings herewith presented. 



