46 PAPERS ON ZOOLOGY OF MICHIGAN. 



GENUS ISCHNURA CHARPENTIER. 

 Imagos. 



A. Segments eight and nine of the abdomen blue with a black stripe on each side. 



I. verlicalis 



AA. Segments eight and nine of the abdomen black. 



I. posita 



Nymphs. 



A. Labium with six lateral setae on each side. 



I. verlicalis 

 AA. Labium with five lateral setae on each side. 



/. posita 



Ischnura verticalis (Say). — This species was taken from the swifter 

 water of the station about two miles down Maple River. 



Ischnura posita (Hagen). — This species was taken from the same 

 habitat as /. verticalis. 



FAMILY AESHNIDAE. 



This family is represented in the Douglas Lake region by two sub- 

 families. 



Imagos. 



A. Eyes distinctly separated above on the middle of the head. 



Subfamily Gomphinae 



AA. Eyes meeting above in the middle line of the heaa. 



Subfamily Aeshninae 



Nymphs. 



A. Antennae four jointed, broad and flat; superior appendage not notched at the ape.x. 



Subfamily Gomphinae 



AA. Antennae six or seven jointed; superior appendage notched at the apex. 



Subfa'mily Aeshninae 



SUBFAMILY GOMPHINAE. 



Imagos. 



A. Both triangles with a cross vein. 



Gomphoides 



A.^. Both triangles without a cross vein, (except the discoidal triangle in Hagenius). 



B. First and second anal veins angulated toward each other at the cross vein of 

 the anal loop, which contains from three to five cells. 



C. Discoidal triangle without cross veins; anal loop three celled. 



Ophiogomphus 

 CO. Discoidal triangle four sided, with cross veins: anal loop three to five, 

 usually four celled. 



Hagenius 



BB. First and second anal veins nearly parallel; anal loop one or two celled. 



D. Hind femora with five to seven long spines in addition to the usuai short 

 ones. 



D romogomphus 



DD. Hind femora with the usual short spines but with no long ones. 



Gomphus 



