514 



Thorax blue or brown and black ; caudal and cephalic lobes of the 

 pronotum with more or less blue or brown ; mesostigmal plates ( Fig. 

 140) without projections on the caudal margins; mesopleural stripe of 

 black, somewhat narrower than that of the male, separating more dis- 

 tinctly from the suture at the caudal third, the ventral branch fre- 

 quently stopping short of the caudal margin of the sclerite ; legs paler 

 than those of the male, the femora usually with two dark stripes one 

 on each side of the carina, the remainder pale blue or brown; tibiae 

 with a black ventral stripe between the rows of setae which frequently 

 includes one of tlie rows; tarsi often with the proximal segments pale. 



Abdomen : lateral surfaces, ajiical ring, and narrow mesal lines of 

 the first tergum pale, the black confined to two dorsal basal spots; sec- 

 ond tergum with broad lateral blue stripes and a dorsal stripe greatly 

 contracted and then widened again shortly before the ape.x, the black 

 limited to a narrow apical ring and a dorso-lateral stripe on each side ; 

 segments 3-7 as in the male with the exception of a narrower mid- 

 dorsal pale line; tergum nine black with a paler narrow ai)ical line, the 

 tenth yellowish or blue, with a narrow- basal ring, the segment usually 

 dark below ; anal appendages of the usual type, the superiors black or 

 dark, the inferiors slightly paler in color; ovipositor, except the ex- 

 treme tip and the prostyles, dark brown or black. 



Measnrcmrntft 



Length, 3 34-37 mm. 



Length, 9 3.^-37 mm. 



Length of abdomen, S 2G-30 mm. 



Length of abdomen, 9 28 nnn. 



Length of hind wings, $ 20-22 mm. 



Length of hind wings, 9 24 mm. 



Width of hind wings. S 4.5 mm. 



Widtli of hind wings, 9 5 mm. 



The nymphs of this species have been taken beneath rocks in 

 swift currents. A single specimen has been reared and a comparison 

 of the nymph with the nymph- of apicclis shows them to be almost 

 identical. Necdham ('03) separates the two species on the character 

 of the lateral setae, but there is so much variation in af^icalis that the 

 character seems w-ithout value. 



The adults are common throughout the state and may be found 

 at almost any point along the banks of clear, swift streams. 



