292 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.49. 



specimens segment 6 is marked similarly to segments 3, 4 and 5.) 

 The posterior bands contain on either side a blue triangle. 



Segment 7 with a heavier development of the color pattern than on 

 segment 6, making the entire dorsal half of the segment black except 

 a narrow blue band across the anterior end. 



Segment 8 pale blue with a minute spot on each latero-posterior 

 edge. 



Segment 9 pale blue with posterior edges and appendages vari- 

 ously marked with black. 



The teneral color of the male is a pale gray or chalky white. In 

 changing from the chalky white to the intense blue the male passes 

 through brown, brownish violet, and violet blue stages. 



Female. — More robust than the male, especially the abdomen. 

 Wings relatively longer than in the male, which when folded reach 

 to the middle of segment 8 and occasionally to middle of segment 9 ; 

 hyaline but with a decided flavescence. Stigma rarely surmounting 

 more than one cell. Wings not proportionally broader than in the 

 male. Among 20 females tabulated, the usual number of antenodal 

 cells was 4 in each fore wing and 3 in each hind wing, Avith variations 

 of one either way. The average in the 20 females was, right fore wing 

 3.9, left fore wing 4, right hind wing 3.1, and left hind wing 3.1. 



Legs short, the last femora reacliing the first abdominal segment. 

 Mesostigmal laminae large (see fig. 49) ; the anterior end of the mid- 

 dorsal carina prolonged between them into a wide triangular en- 

 largement, and each mesostigmal lamina extended posteriorly in a 

 plate or ridge, which overhangs its respective postero-lateral depres- 

 sion. 



Female, live color. — The females of Argia vivida are more variously 

 colored than any sex of any odonate species I have seen. As in the 

 male, the teneral is a chalky white, which changes through various 

 shades of gray-violet and brown into a high color largely blue, which 

 gives the female the general appearance of the male in high color. 

 This blue color was rare, as I found few specimens in it, but I took 

 most of my vivida series early in their season. Of four females taken 

 on lower Satus Creek on August 24, only one was blue. 



Female, blue form. — Labium brownish gray; labrum grayish blue; 

 clypeus, nasus, frons and vertex greenish blue slate. Occiput and 

 postocular areas blue with a tinge of violet. Markings of the head 

 same as described for the male with the same individual variations. 

 Eyes blue above, shading into violet gray below (in one high colored 

 female my notes mention, "eyes violet gray"). Scattering white 

 pile on the labrum, frons and nasus, also on the postocular areas 

 and occiput. Antennae black. 



Prothorax \dth dorsal and lateral surfaces blue; ventral surface 

 and coxae pale brownish ; femora gray; tibiae pale gra}dsh blue, AU 

 markings as in the male. 



