174 NEUROPTERA OF NORTH AMERICA. 



first sector of the triangle sinuated ; triangle moderate, broad ; 

 caudal appendages short ; the genital organs not prominent ; vulva 

 obtected ; the sides of the eighth segment in the female not di- 

 lated. 



1. D. assimilata! 



Libellula assimilata Uhler ! Proc. Acad. Philad. 1857, 88, 6. 



Yellowish ; mouth and front pale yellow, a narrow black band 

 before the eyes; dorsum of the thorax luteous, sides yellow; ab- 

 domen slender, the base compressed, inflated, yellowish, dorsum of 

 the first and second segments black at base, segments 49 each 

 side with a marginal, black stripe ; appendages yellowish, the in- 

 ferior one triangular, truncated at the apex and a little excised ; 

 vulvar lamina short, narrow, almost quadrangular, inflated, bifid, 

 recurved at the apex ; feet black, the femora partly yellowish ; 

 wings hyaline, the base flavescent, the basal half with the males 

 and sometimes with the females, flavescent ; pterostigma short, 

 yellow, obscure in the middle, membranule white ; 7 9 antecubi- 

 tals ; 6 8 postcubitals ; three discoidal areolets. 



Length 33 37 millim. Alar expanse 56 60 millim. Ptero- 

 stigma 2J millim. 



Hob. Fort Union, Nebraska (Dr. Suckley) ; Illinois and Wis- 

 consin (Kennicott) ; St. Louis ; Washington ; Chicago (Osten 

 Sacken) ; Pennsylvania ; Maryland (Uhler). 

 i It is very much like Diplax flaveola Linn, of Europe. 



2. D. madida ! 



Diplax madida Hagen ! 



Flavescent; dorsum of the thorax luteous ; the sides yellow, with 

 two of the sutures black; abdomen yellowish, the two basal seg- 

 ments black at base ; segments 3 5 each side with the lateral 

 margin and a lateral stripe, black; feet black, the anterior femora 

 yellow beneath ; wings fumose, the anterior margin, and the base 

 of the posteriors, flavescent ; pterostigma long, narrow, yellow ; 

 membranule white. Female. 



Six antecubitals ; six postcubitals ; three discoidal areolets. 



Length ? Alar expanse 58 millim. Pterostigma 3 millim. 



Hah. Upper Missouri. 



Described from a single, mutilated specimen ; the head, and apex 

 of the abdomen is destroyed. 



