550 



ish; anal appendages of the usual type; the lateral valves of the ovi- 

 positor are pale yellow, the prostyles light brown ; apex of the eighth 

 sternum with a long seta. 



Measureine7its 



Length, S 30 mm. 



Length, 9 30 mm. 



Length of abdomen, S 23-24 mm. 



Length of abilomcn, 9 23-24 mm. 



Length of hind wings, $ 17 mm. 



Length of hind wings, 9 17 mm. 



Width of hind wings, S 3.5 mm. 



Width of hind wings, 9 4 mm. 



A common species in the lake region of Illinois, but not observed 

 as far south as Urbana. The adult female is closely related to cantiicu- 

 latu)}i and ck'ilc, from whicli it may be separated by means of the 

 wing venation, the vein Mo usually arising between the third and 

 fourth postnodal cross-veins, by the narrower pale abdominal rings at 

 the bases of the terga, and Iiy the character of the mesostigmal plates. 

 The males are easily separated from canmciilatiiiu and ck'ilc liy means 

 of the anal appendages. 



Enai.i,.\gm.\ roLi.uTUM (Hagen) 



Ah'i-nph. — Color, pale green or huff. 



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

 angles slightly projecting and furnished with but few setae; antennae 

 of the usual form as regards length of the segments, the first two 

 segments, however, being much thicker than the distal ones and the 

 second usually shorter than the first; first antennal segment dark in 

 color, the remaining ones paler; labium extending slightly caudad of 

 the first pair of coxae, with three mental setae ; five lateral setae and 

 tiiree or four marginal setae on the median lobe. 



Thora.K about twice as long as broad; legs light in color, with 

 a few scattered setae, the femora with preapicah rings of brown, the 

 tibiae sometimes with a dorsal row of black dashes; metathoracic 

 wing-cases reaching the midillc of the third abdominal segment. 



Abdomen slender, the lateral keels strongly developed and setose, 

 the setae being grouped conspicuously near the apices of the keels, 

 especially on segments 2-6; dorsa of segments 4-10 with apical trans- 

 verse rows of small setae, the row on the tenth interrupted on the 

 line of the meson, and those on 2-5 irregular, and consisting of several 



