DRAGONFLIES OF DOUGLAS LAKE REGION. ol 



Nymphs. 



A. Lateral abdominal appendages more than half as long as the inferiors; hind femora longer 

 than the head is wide. 



Subfamily Cordulinae 



AA. Lateral abdominal appendages less than lialt the length of tlie inferiors; hind femora 

 ge lerally as long as the head is wide. 



Subfamily Libellulinae 



Subfamily Corduliinae. 



KEY TO THE GENERA OF CORDULINAE. 



Imagos. 



A. Triangle of the hind wing placed considerably beyond tlie arculus. 



Macromia 

 AA. Triangle of the hind wi.ig retracted to the level of the arculus or even passing it. 

 B . Triangle of the liind wing with a cross vein. 



Epicordulia 



BB . Triangle of the hind wing without a cross vein. 

 C . Wingo with black basal markings. 



Tetragoneuria 

 CC . Wings clear. 



Cordulia 



Nymphs. 



A. Head with a prominent, pyramidal horn. 



Macromia 

 AA. Head without a prominent, pyramidal horn. 

 B . Lateral setae four or five. 



Epicordulia 

 BB . Lateral setae seven. 



C . Abdomen with large dorsal hooks. 



Tetragoneuria 



CC . Abdomen without dorsal hooks. 



Cordulia 



GENUS MACROMIA RAMBUR. 



Macromia illinoiensis Walsh. PI. IX, Fig. C; PI. X, Fig. A.— This 

 spider-Hke njTnph was onl}- taken twice, once on ]\Iaple Kiver and once 

 in the shallow water along the lake shore near camp. The nymphs 

 taken on Maple River were from vegetation along the shore but the 

 specimens taken at camp (these may have been wave- washed in- 

 dividuals) were found on the piles of the dock. No adults were taken. 



GENUS EPICORDULIA SELYS. 



Epicordulia princeps (Hagen). — This species was found to be rather 

 rare, only a few nymphs occurring in the collections from Maple River. 



GENUS TETRAGONEURIA HAGEN. 



Tetragoneuria spinoso (Hagen). — Nymphs of this species were taken 

 in Maple River, Biyant's Bog, and the beach pool west of North Fish- 



