476 



There are two representatives of this species in the collection of 

 the Illinois State Lahoratory of Natural History, both of which were 

 collected at Havana, Illinois. There are also three specimens in the 

 Bolter Collection of the University of Illinois, which are without 

 locality or date labels. 



H. tricolor Burmeister is a synonym of //. titia (Williamson, '12). 



Family COBNAGRJONIDAE 



The nymphs of this family possess flattened gills, the lateral ones 

 being flattened as well as the median. The median lobe of the labium 

 does not have a deep cleft, and tlie basal segment of the antenna is 

 small and does not exceed the second in length. 



The adults are often brightly colored, frequently marked with 

 bright blue or green, but the wings are mostly clear and without smoki- 

 ness or tints of any kind. The antenodal cross-veins are few, never 

 more than two in number in Illinois species, and the postnodals are 

 also much reduced and fewer in number than in, the Agrionidae. The 

 interpleural suture is never distinct as far cephalad as the metathoracic 

 spiracle.* 



Key to Subfamilies 



NYMPHS 



a. Median lobe of labium spoon-like (Fig. 10), the narrowed portion usu- 

 ally much longer than the expanded portion ; gills (Figs. 48-52) more 



or less spatulatc, the margins nearly parallel and the tips blunt 



Lestixae. 



aa. Median lobe of labium not spoon-like (Figs. 11-13), the narrowed 

 portion not much longer than the expanded portion; gills lanceolate, 

 acutely i)()intcd at the tip, the margins not parallel. . Coexagrioxin'.\e. 



ADULTS 



a. M, arising much nearer the arculus than the nodus (Fig. 85) ; front 



without pale color immediately above the clypcus Lestixae. 



aa. Mj arising much nearer the nodus than the arcidu.s (Figs. 81-84, 



87-90) ; front with a pale stripe immediately a^ove the elypeus 



Coexagrionix.\e. 



*The use of the accessory genitalia in si'ii.irating the males of closely allied 

 members of this family has failed to prove entirely satisfactory for such species as 

 Lestes forcipat ii.i and dU'junclux and the Knallagma {{""("'P composed of E. cnh-rrti. 

 rarunculaUim, civile, dii'npans, and doiihhdai/i. The structure of the penis in the 

 Enallagma group (Fijjs. 97.99,101,107.108") is so uniform that the advantage gained by 

 using the character is slight. It may be found that many of the.se species interbreed 

 — a condition already known to be true of caninculatiim and civHc — and it seems 

 almost certain that future investigators will unite L. forciiwtus and disjunctus 

 when more complete biological data are in hand. 



