28 DRAGON'FLIES OF OHIO. 



outer side acting as a stop as it impinges against the 

 edge of 10. The inferiors are much longer, strongh^ 

 bifid ; the upper branch smaller, rounded, the lower 

 stout, directed downward and backward, the edges are 

 strongly denticulate, and the apex acute. 



The appendages of the female are rather long and 

 slender, the valves narrow, light colored. 



The handsomest of our Argias, is rather common 

 along larger streams in the southern part of the state. 



ERYTHROMMA, Charpentier. 



The single North American species of this genus 

 occurs sparingly in this state; indeed it may be con- 

 sidered as rare. , 



Erythromma conditum, Hagen. 



Length : of abdomen rf ? 28 ; of hind wing cf' 20, 

 ? 23. 



The general color is black in both sexes, marked 

 with blue and yellow in the male, as follows : blue, 

 front of head (except postclypeus) labium, anterior 

 border and spot on sides of prothorax, a wide humeral 

 sinuous within, a mid-band on sides and thorax, 

 stripes on the femora and tibife, the sides and apical 

 rings on 1 and 2, interrupted basal rings on 3—7, and 

 the whole of 8 and 9; yellow, labium and posthumeral 

 (pale,) and the sides of the metathorax (bright). The 

 female differs in having more black and paler blue on 

 the head, the sides of the thorax with more and deeper 

 yellow, the blue humeral narrower and paler, the first 

 abdominal has a small square basal, black spot with 

 sides and apical ring blue, the dorsum of 2-10 black, 

 except the interrupted basal rings. 



