75 



Rock River, in northern Illinois; from the Sangamon, in the 

 central part of the state ; and from the Big Muddy at the south. 



Transformation was first observed May 21. Mr. Needham's 

 notes of his observations on this species while at Havana are 

 as follows: "Transformation takes place in the night or very 

 early morning. The nymph crawls but a little distance (one to 

 two feet) out of the water before fixing itself for emergence. I 

 have found exuviae on bridge piers and on willow stumps, and 

 have taken imagos emerging in such places at about six o'clock 

 on several mornings." 



The strong-flying imago was not uncommon at Havana 

 during July, 1896. The males were frequently seen chasing 

 each other over the open river, or sitting at rest on the sand at 

 the bank with the abdomen elevated and the wings declined 

 until their tips touched the sand, in a position of great alert- 

 ness. The females fly less openly. One female captured in the 

 weeds at the bank, deposited for me in a watch-glass of water 

 in a few minutes' time about 5,200 eggs. This number is an 

 estimate from a partial count. 



An observation on the food of the imago was made by Mr. 

 Needham, who found on shore a female fraiernus engaged in 

 eating a teneral imago of Mesof/iemis simplici colli s. 



Examples of the nymphs collected in June were placed in 

 breeding-cages immersed in the water of Quiver Lake beside 

 the field laboratory of the Biological Station. They remained 

 without transforming, and at the close of the season's work, 

 September 28, seventeen nymphs, nearly the original number, 

 were still alive in the cage. 



About the middle of July, after a severe rain storm, sev- 

 eral dead males of this species were picked up from the guards 

 of cabin-boats along the Havana river-front. 



The imago is reported from Elinois, Nebraska, Kansas, 

 Texas, and New Mexico. In Illinois it has been taken in Hen- 

 derson county, as well as at Havana and Rock Island.* 



*According to Calvert, the imagos described as externus by Kellicott (.99) and 

 Williamson ('oo) are G. crassiis Hagen, a species not yet found in Illinois, which is 

 quite unlike externus in the form of the terminal appendages of the male. 



