Occasional Papers of the Museum of Zoology 15 



c\ Area enclosed b}- -the fork below of the thoracic middorsal 



carina entirely or partly pale albifrons. 



c". Area enclosed by the fork below of the thoracic middorsal 

 carina entirely black. 

 d\ No trace of a longitudinal median dorsal pale stripe on 



the abdomen crythrogastrum. 



d^ A very narrow thread-like longitudinal median dorsal pale 



stripe on abdominal' segments 3 to 5 or 6 aUcniim. 



h\ A black longitudinal dorsal stripe on either side of abdominal 

 segment 2, enclosing a median pale stripe which does not reach 

 the apex; 3 with a distinct pale basal ring joining a pale longitud- 

 inal median stripe. 



c\ Abdominal segment 9 with a black basal spot on either side, 

 enclosing a distinct pale median bar which extends from the 

 base to more than half the length of the segment; appendages 



black iiiitratHin. 



c". Abdominal segment 9 pale or obscured but without definite 

 pattern ; appendages more or less pale, especially at the base. 

 d\ Size large, abdomen over 35 mm. in length ; anal vein 

 separating from the posterior border near or at the cubito- 



anal cross-vein uiajiis. 



d^ Size small, abdomen less than 35 mm. in length ; anal vein 

 separating from the posterior border at the level of or 

 distad to the arculus pcrcgriuum. 



Key to Species of Group 4, O.vystigiiia 



a\ Male. — Thorax black or dull above, lateral pale markings obscure ; 

 face largely blue. Male and female.- — Quadrangle short, not reaching 

 the level of the nodus ; Rs and ISl^ widely separated at their termin- 

 tion, Rs turned toward ^L. cyaiiofroiis. 



■d\ [Male. — Thorax with dorsal and humeral pale stripes or lines, dorsum 

 and sides bright, not obscure, and color pattern definite; face black. 

 Male and female. — Quadrangle long, reaching the level of the nodus; 

 Rs normal at its termination pctiolafiiiit. 



Discussion of SPEciiis 



I. Heteragrion fiavovittatum Selys 

 Figures \2, 13, 119, 120, 133 



This species has been recorded from ]\Iinas Geraes, Jirazil. 

 There are a male and a teneral female in the Hagen collection, 

 both imperfect. Each has a small label "Hagen", a small blue 



