No. 39] ODONATA OF CONNECTICUT: AGRIONIDAE 109 



The adults are dark species, the cuticle being blue or green and 

 shiny or metallic in appearance ; wings with a great many cross- 

 veins and few hexagonal or pentagonal cells. 



Nymphs of the genus are found in small meadow or wood- 

 land brooks commonly among the roots of willow trees. The 

 adults are remarkable for their bright metallic coloration and their 

 dark wings, which make them conspicuous when in flight; and 

 they are sometimes known as "blackwings." Calopteryx is a 

 synonym of Agrion. 



The members of this genus are all stream-inhabiting species. 



Key to Species 

 Nymphs 



The nymphs known at the present time do not possess charac- 

 ters enabling one to prepare a key to species. The basal segment 

 of the antennae in aequahile is longer than the head, while in most 

 specimens of maculatum it is slightly shorter. 



Adults, Males 



1. Wings entirely smoky or opaque maculatum 



Wings with apical fourth or sixth only, smoky, the remainder 



hyaline, transparent 2 



2. Occiput without a prominent tubercle on each side aequabile 



Occiput with a prominent tubercle on each side behind the eyes ... 3 



3. Wings with apical fifth or sixth black; antenodal cross-veins 



18-24 dimidiatum apicale 



Wings with apical fourth brown; antenodals about 30 amatum 



Females 



1. Pterostigma without cross-veins ; occiput without prominent 



tubercles; dorsum of segment 10 of abdomen with a sharp spine 2 

 Pterostigma with cross-veins ; occiput with prominent tubercles . . 3 



2. Hind wings not over 36 mm. in length by 9 to 9.5 mm. in width 



aequabile 

 Hind wings more than 36 mm. in length by 8 to 9 mm. in width 



amatum 



3. Pterostigma with 6-12 cells; wings uniformly smoky, sometimes 



slightly darker at tip maculatum 



Pterostigma with less than 6 cells ; wings not uniformly smoky, 

 the apical fourth or sixth darker than the rest 4 



4. Stigma white ; length of hind wings about 30 mm. dimidiatum apicale 

 Stigma yellow ; length of hind wings 38 to 40 mm amatum 



Agrion aequabile (Say) 

 Journal of the Academy of Natural Sciences, Philadelphia, 8 : 33 : 1839. 

 Nymph. — Color dark or light brown. 



Head : basal segment of the antennae longer than the head, the 

 distal segments together about two-thirds the length of the prox- 



