156 Annals of the Carnegie Museum. 



in the anterior two-thirds of each, femora inferiorly, tibiae superiorly. 

 Abdominal segments 8 and 9 blue, with an inferior black stripe on each 

 side occupying the greater part of the length of each segment. Hind 

 margin of abdominal segment 10 with a mid-dorsal excision. Supe- 

 rior appendages not quite as long as 10, extreme apex bifid transversely, 

 inner branch longer. Inferior appendages a little longer than 10, ver- 

 tically bifid, upper branch the longer and more robust, directed 

 upward ; lower branch shorter, slenderer, more acute, directed back- 

 ward (caudad). 



Younger males differ from the above description in having the 

 markings of abdominal segment 2 more distinctly argiaform, in that 

 there is a superior black stripe on each side contracting posteriorly to 

 three-fifths its length, thence widening to its hind end, not reaching 

 the hind margin of the segment, and failing to unite with its fellow of 

 the opposite side ; each side has also an inferior black stripe ; the 

 black on the first three -fourths of segments 3 and 4 represented by ill- 

 defined brownish markings. 



Old males differ from the first description in having a black line on 

 the fronto-nasal suture, a couple of black dots on the rhinarium, a 

 mid-basal black mark on the labrum ; the sides and ventral surface of 

 the thorax and the first two abdominal segments show more or less 

 pruinosity ; segments 3-6 show some tendency to have the inferior 

 lateral margin blackish ventrad to the pale coloring. 



9. The only example of this sex has the head and abdominal seg- 

 ments 3-6 marked as above described for the old males ; segment 2 

 black dorsally with a very small median blue spot, sides pale yellow 

 with an inferior longitudinal black stripe ; 7 similar to 6 ; 8 pale pos- 

 teriorly, its black marks consisting of a pair of dorsal stripes reaching 

 from the base backward to two-thirds of the segment's length, con- 

 fluent with each other for the first third, and each with an adjacent 

 inferior lateral black stripe for the first half of the segment's length ; 

 the inferior lateral black stripe extends the whole length of the seg- 

 ment. Segment 9 black, with a single mid-basal, and on each side 

 at three-fourths' length a posterior pale dot; 10 black, its hind 

 margin narrowly pale, cleft mid-dorsally to base, appendages shorter 

 than the segment, black ; no vulvar spine. 



cT?. Wings uncolored, iridescent, veins pale reddish at base, darker 

 distally ; stigma brown, costal side onlyslightly longer than the proximal 

 ordistal sides, which are subparallel, surmounting usually one cell. Front 



