1911] MuttkowsM, Wisconsin Dragonflies. 35 



With great pleasure I dedicate this species to Dr. E. M. 

 Walker, to whose careful and thorough labors. Entomology, and 

 especially Odonatology, owes so much . 

 *EnaIIagma signatum (Hagen). 



North Hudson, St. Croix Co., July 6-12, two males, one female. 

 Fountain City, Buffalo Co., Aug. 11-17, one male. Golden Lake, Wau- 

 kesha Co., July 7, one male. 

 Enallagma pollutum (Hagen). 



North Hudson, St. Croix Co., July 7-12, one male. 

 Nehallenia irene Hagen. 



North Hudson, St. Croix Co., July 6-12, one male, three females. 

 Amphiagrion saucium (Burmeister). 



Prescott, Pierce Co., July 23, one male. 

 Ischnura verticalis (Say) . 



North Hudson, St. Croix Co., July 6-12, twelve males, forty-four 

 females. Prescott, Pierce Co., July 20-26, one male. Maiden Bock, 

 July 27-Aug. 3, one male. Fountain City, Buffalo Co., Aug. 12-17, 

 fourteen males, nine females. 



There appear to be two forms of this species, a smaller one 

 in which the abdomen measures 20-21 mm., and a larger form 

 in which the abdomen measures 25-27 mm. Except for the size 

 of the latter I am unable to find any differences, save that the 

 lateral sutures of the thorax have more black. The remainder of 

 such differences as I found are all covered by the great variation 

 of verticalis. Forms having the anteumeral stripe changed in a 

 ! spot are not at all rare. One male from North Hudson has the 

 thorax entirely black on the dorsum. The larger forms appear 

 to have different appendages, but the range of variation in the 

 smaller forms is so great that it would be difficult to establish an 

 identity on that basis. 



These larger forms likewise occur at the same time and the 

 same places as the smaller forms and are associated with them 

 throughout their period of flight. For a time I thought that this 

 might be a geographiccal variation of verticalis, as only larger 

 forms were represented in the material taken along the St. Croix 

 river in 1909. But I captured several specimens at North Hudson 

 in 19 10, and also found them in Milwaukee county though never 

 so numerous as the small form. In all cases, except at the St. 

 Croix river, they associated with the small typical form. 



