4G6 



In the following descriptions "length" refers to the length of 

 the body without appendages, and does not include caudal gills, anal 

 appendages, or antennae. In the color descriptions, where suitable 

 material was at hand, the colors were matched with colors given by 

 Ridgway in his "Color Standards and Color Nomenclature" ('12), 

 and the names of colors which appear in parentheses are from that 

 author. 



Family AGRIONIDAB 



The nymphs of this family are easily distinguished from those 

 of the Coenagrionidae. The three-sided gills, the deeply cleft median 

 lobe of the labium, the large basal segments of the antennae, the un- 

 equal length of the gills, and the heavy and sprawling appearance of 

 the legs are characteristic. 



The adults are, as a rule, bright or strikingly colored, such colors 

 as metallic green and carmine being common. A large number of 

 antenodal cross-veins between costa and subcosta and the presence of a 

 distinct interpleural suture are also diagnostic* 



Subfamily AGRIONINAE 

 Key to Genera 



NYMPHS 



a. Median cleft of median lobe of labium extending proximad of the 



articulations of the labial palpi ; body color usually dark Agrion. 



aa. Median cleft not extending proximad of the articulations of the labial 

 palpi ; body color usually light Hetaerina. 



ADULTS 



a. Wings with the basilar space, cell first M, without cross- veins ; meta- 



pleural suture only with a pale stripe Agrion. 



aa. Wings with a basilar space provided with cross- veins ; mesopleural, 

 interpleural, and metapleural sutures with pale stripes .... Hetaerina. 



Genus Agrion Fabricius 



In the nymph the median lobe of the mentum is provided with a 

 deep cleft which extends far proximad of the articulations of the 



*Only one genus in this family is known in which the interpleural suture is 

 not well developed, and since that genus does not occur in the United States, this 

 character has been included in the family dei^cription. 



