DRAGONFLIES OF THE MISSISSIPPI VALLEY COL- 

 LECTED DURING THE PEARL MUSSEL INVESTIGA- 

 TIONS ON THE MISSISSIPPI RIVER, JULY AND 

 AUGUST, 1907. 



By Charles Branch Wilson, 

 Department of Biology, State Normal School, Westfleld, Massachusetts. 



INTRODUCTION. 



Many opportunities were afforded for the collection of dragon- 

 flies in connection with the pearl mussel investigations on the Missis- 

 sippi River and its tributaries during the summer of 1907. So far 

 as practicable these opportunities were improved and a list is here 

 presented of the different species obtained, with their geographic 

 and seasonal distribution. Some of the territory visited had been 

 previously worked over by dragonfly investigators in a more thorough 

 and satisfactory manner, but much of it also was new and is here 

 reported upon for the first time. 



Then, too, all the previous Avork had been disconnected, confined to 

 a single State or even a single locality, and hence there was not the 

 same chance for correlation and comparison. 



The present is the first attempt, so far as known, to collect from 

 any considerable extent of the Mississippi River and its tributaries ; 

 and while it is confessedly deficient in many particulars, it neverthe- 

 less affords a general outlook that may be of some value. The 

 itinerary of the trip, so far as dragonfly collecting was concerned, 

 Avas as follows: 



The time between July 6 and 12 was spent at St. Paul in examining 

 some of the numerous small lakes with which that city and Minne- 

 apolis are surrounded. Leaving St. Paul on the 12th, a run was 

 made down the Mississippi to Prescott, Wisconsin, where the party 

 remained until the 15th. On that date the St. Croix River was 

 ascended as far as Stillwater, Minnesota, where a stop of twenty-four 

 hours was made, during which time dragonflies were collected from 

 both banks of the river and from a small lake in the outskirts of 

 the town. Returning to Prescott the next forenoon and continuing 

 down the Mississippi, the party stopped at La Crosse, Wisconsin, 



Proceedings U. S. National Museum, Vol. XXXVI— No. 1 692. 



653 



