NO.2107. DRAGONFLIEH, WASITINGTON AND OREGON— KENNEDY. 283 



Female, hrown form. — The larger number of females are of this color, 

 which is as follows: Labium and labrumgray; clypeus, nasus, frons, 

 and vertex pale reddish brown. The postocular areas the most red- 

 dish of any part of the insect. Eyes pale brown above, brownish 

 gray below. Antennae black. 



Prothorax pale brown above, lighter below. Legs pale brown. 



Mesothorax and metathorax yellowish brown on dorsal and anterior 

 surfaces. Coxae and trochanters same shade, femora and tibiae pale 

 brown. Wings hyaline, stigma almost white. 



Abdominal segments 1-7 brownish olive gray, shading into brownish 

 on segment 8. Segments 9 and 10 pale grayish browai. 



All markings same as described for the blue female. 



The system of markings in Argia seems to be a generic character, as 

 it occurs with various modifications from sex to sex and species to 

 species. Tlie more generalized pattern occurs on the females (see 

 figs. 29, 30, 33, 34, 60, and 61). The coloration of the males is more 

 widely divergent, but is understood when its evolution from the 

 "female form" in the male teneral is considered (see figs. 5S and 59, 

 of male teneral emma). 



Nymfli (figs. 35, 36, 65-70). — This is a vigorous, long-legged and 

 contrastingly colored nymph with large gills. 



Length of abdomen, without gills, 12 mm.; length of gills, 5; width 

 of head, 3.5 ; length of hind leg, 11. The specimens are shrunken from 

 having been put into strong alcohol. 



Head broader than long, the posterior margin noticeably emar- 

 ginate. Five round white dots between the compound eyes (the 3 

 ocelli and 2 other similar white dots). A broad white stripe on each 

 postocular lobe. Antemiae longer than head, slender, base and first 

 joint white, the remaining joints black. Mentum 1^ times as long as 

 broad; posterior edge one-half as wide as anterior inargin; ligula 

 angular. Each lateral lobe with a single raptorial seta just below the 

 base of the movable hook, a notch separating the end hook from the 

 inner margin. 



Prothorax more than twice as broad as long, the ridge around the 

 posterior edge very prominent, and running down on to the side to the 

 coxae. Dorsal surface strongly convex with a median gi'oove. Femora 

 of first pair of legs thi'ee-fourths as long as femora of second pair. 

 Mesothorax and metathorax equal and either slightly longer than the 

 prothorax. A deep concavity extending from anterior point of 

 anterior wing pads to mesinfraepisternum. Femora of second legs 

 extending beyond the posterior margin of abdominal segment 4. 

 Tubercle between the upper edge of mesinfraepisternum and posterior 

 edge of prothorax drawn out dorso-ventrally, making a low vertical 

 ridge. Posterior pair of wing pads extending to posterior edge of 



