206 ENTOMOLOGICAL SOCIETY 



Nemoura completa Walker. 



Tcznioptcryx similis Hagen. 



Hagen's type was from Washington, in May, but I have not 

 seen the species here. 



Leuctra tenuis Pictet. 



Recorded by Hagen. There are apparently two species here, 

 but whether either is Pictet's is not yet certain to me. 



Suborder ANISOPTERA. 

 Family EPHEMERID^E. 



Polymitarcys alba Say. 



Sometimes to be found in great numbers at lights all through 

 the city, in July and August. 



Hexagenia bilineata Say. 



Our most common mayfly, especially abundant in the latter 

 part of June and early in July, but found all through the summer. 



Hexagenia limbata Pictet. 



Much less common than the preceding species. Found in July. 

 Leptophlebia cupida Say. 



Common early in Spring from March to May. 

 Ephemerella excrucians Walsh. 



Found in Washington at light. 

 Habrophlebia americana Banks, 



One specimen from Washington, 2ist July. 

 Siphlurus aridus Say. 



One from Falls Church, Va., roth August. 

 Bsetis vicina Hagen. 



Plummer's Island, Md., August. 

 Bsetis unicolor Hagen. 



Described from Washington. I have not seen it from here, 

 but from New York. 

 Cleon mendax Walsh. 



'Quite abundant in spring and fall. 

 Cleon sp. 



Specimens of a larger species from Washington, collected in 

 October. 



Callibsetis fluctuans Walsh. 



Washington, D. C,, and Falls Church, Va., July. 



