496 



on the caudal half; terga 2-10 all with brown, dorsal, longitudinal 

 bands, extending from the cephalic nearly to the caudal margins, the 

 bands being slightly enlarged at the caudal ends; terga 2-10 with nar- 

 row rings of brown on the caudal margins; sterna 3-8 black; nine and 

 ten, pale; anal appendages (Figs. 125, 126) consisting of strong su- 

 periors, coarsely tuberculate on the lateral surfaces and hairy at the 

 apices, the mesal margins possessing a large basal tooth and a number 

 of smaller ones beyond this to about the distal third; inferior appen- 

 dages sigmoid, the distal two-thirds curved in an opposite direction to 

 the superiors. 



Female. — Color similar to that of the male. 



Head and thorax identical with those of the male. 



Abdomen similar to that of the male with the exception of the 

 dorsa of the cephalic terga, which are as a rule paler in color, and 

 terga nine and ten, which possess a mesal dark line ; ovipositor reach- 

 ing apex of tenth segment, the lateral valves black below, the ventral 

 margins serrate or coarsely toothed. 



Measurements 



Length, $ 39 mm. 



Length, 9 35 mm. 



Length of abdomen, S 27 mm. 



Length of abdomen, 9 27 mm. 



Length of hind wings, $ 21 mm. 



Length of hind wings. 9 22 mm. 



Width of hind wings, $ 5 mm. 



Width of hind wings, 9 5 mm. 



A very common species at UYbana, occurring in abundance in 

 pools north of town. The nymph is easily separated from rcctaugu- 

 laris and forcipatus by means of the shape of the gills. The adult is 

 also easily separated from rectangularis and forcipatus and seems to 

 be most closely related to uucatus, from which species it differs mainly 

 in color though also in the shape of the anal appendages of the male and 

 the length of the ovipositor of the female. The nymph is more closely 

 related to uncatus than to any other species. 



The species has a wide distribution in Illinois and flies from early 

 June to August. 



Lestes vigilax Hagen 



Nymph. — Color, light brown or green. 



Head broad, about twice as broad as long, the caudo-lateral angle 

 not projecting and without setae ; antennae slender and of the usual 



