AQUATIC INSECTS IN NEW YORK STATE 



259 



ISCHNURA 



This cosmopolitan genus contains a few very common and! 

 widely distributed and well known species. I include three in 

 this paper, one of which I. p o s i t a , has been referred hitherto^ 



Fig. 12 Labia of Enallagma and Ischnura ; a and b, labium ofE. signatum; 



c and d, of I . v e r t i c a 1 i s 



to Nehallennia. The one reason for referring it to Nehallen- 

 nia, the absence of a spine on the apex of the sternum of the- 

 eighth abdominal segment in the female, appears not to be a 



Fig. 13 Eggs of Ischnura verticalis 



good one, since a number of species are now referred to Ischnura 

 lacking that spine. Ischnura and Enallagma are not very 

 sharply defined from each other, and this troublesome species 

 stands in some respects intermediate in characters between the 



