280 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.49. 



females of each species of Argia. By referring to figure 48 it will be 

 seen that the whole organ (formed of the anterior end of the middorsal 

 carina and the two laminae) is narrow antero-posteriorly, that the mid- 

 dorsal carina ends in it abruptly, instead of widening out into a broad 

 triangle as in vivida, and that the two posterolateral depressions are 

 less sharply defined than in vivida. The minute spines on the posterior 

 edge of the abdominal segments are long and slender as in the male. 



Female, live color. — In some females in advanced age the color is a 

 slate blue. Tenerals are as in the male (see figs. 60 and 61), a light 

 tan or creamy white, changing then through darker shades of brown 

 to olive, and in some specimens, perhaps 5 per cent, of those captured 

 to a further stage of slate blue. In drying, the blue specimens change 

 to an olive brown. The females may be dichromatic, as both blue 

 and brown females oviposit. 



Female, hlue form. — Labium and labrum broAvnish gray ; clypeus, 

 nasus, f rons . and vertex, bluish slate. Postocular areas pale gray. 

 Under surfaces of head brownish. Eyes grayish brown above and 

 whitish below. Head sparingly covered with white pile. Markings 

 on the head same as described for male, and showing the same indi- 

 vidual variation. 



Prothorax bluish slate above, brownish on the sides, and heavily 

 pruinose below. Markings same as described for the male. 



Mesothorax and metathorax strikingly blue on anterior and dorsal 

 surfaces, also on sides to below humeral suture. Lower sides and 

 ventral surfaces pale olive brown overlaid with pruinose. Legs light 

 brown and pruinose, less heavily striped than in the male. All other 

 thoracic markings same as described for the male. Wings hyaline, 

 lightly flavescent in some individuals; stigma cream. 



Abdominal segment 1 pruinose. (See figs. 29 and 30.) 



Segment 2 blue with an olivaceous cast. A narrow black ring 

 around its posterior end. Two small oval spots on the dorsal surface 

 of the posterior third. 



Segment 3 very blue, the bluest of the abdomen. A narrow black 

 ring around its posterior end. On either side a narrow oblique spot 

 running ventrad and caudad in the extreme ventro-posterior angle of 

 the pleurite. On the posterior end of the dorsal surface a U-shaped 

 spot opening cephalad. 



Segment 4 less blue than segment 3. As in segment 3, a narrow 

 band around the posterior end, and a nan-ow oblique spot running 

 ventrad and caudad in the angle of the pleurite. A narrow stripe, 

 broader cephalad, running along either upper side. These stripes* 

 begin from the anterior end of the segment at about twice the width 

 of the posterior bands, and terminate at the middle of the segment. 

 On the posterior end of the dorsal surface a U-shaped spot, but with 



> These stripes are termed by Calvert In the Biologia Centrali Americana, "post-basal streaks." 



