36 Bulletin Wisconsin "Natural History Society. [Vol. 9, Nos. 1-2. 



Mr. Wiliamson writes me that he has taken both forms at 

 Bluffton, Ind., and that they occurred at the same time and in the 

 same places with the others. These experiences are identical with 

 my own observations. 



GOMPHINW. 

 Gomphus fraternus (Say). 



Prescott, Pierce Co., July 13-19, eight males, ten females. 

 Gomphus ventricosus Walsh. 



Prescott, Pierce Co., July 13-19, one male. 

 Gomphus vastus Walsh. 



Prescott, Pierce Co., July 13-19, one female. 

 Gomphus externus Hagen. 



Prescott, Pierce Co., July 13-19, two males and three females. 



All the Gomphinw were taken on the sand flats in the Missis- 

 sippi river below Prescott. The dams erected by the government 

 to correct the basin of the river have caused large deposits of 

 sand between these dams. In times of high water the dams, as 

 well as the flats between them, are covered by the water, but in 

 the summer drouth these flats were exposed to a great extent. 

 They were frequented by the Gomphinw. Libellula pnlchella and 

 Sympetrum corruptum, the latter two species flying around and 

 over the stagnant pools left by the withdrawal of the river. I 

 also saw a lonely Perithemis tenera male, which was too wary 

 to permit its capture. G. fraternus was most common, although 

 I rarely saw more than two or three specimens at a time. The 

 Gomphinw were very curious and would fly near me, at length 

 settling down on the sand a short distance away, usually within 

 ten feet. After trying at various times to sweep them in my net 

 I found that by simply covering them with the net as they rested 

 on the sand I could obtain better resuls. 



I was rather surprised that G. fraternus did not hunt the vege- 

 tation of the shore line as is the case along the Milwaukee river, 

 where I have taken it and also quadricolor from the flowers and 

 in the reeds growing within ten feet of the water. G. externus 

 usually hunted such resting places where the sand was sufficiently 

 mixed with loam to permit the growth of a scanty vegetation. 

 But fraternus invariably hunted the naked sands near the imme- 

 diate edge of the water. 

 Gomphus lentulus Needham. (Plate IV, figs. 14, 15 and 16) . 



