42 U. S. NATIONAL MUSEUM BULLETIN 209 



evanescent apically and somewhat higher, broadened, and flat-topped 

 basally. 



Black. Part of mandible, clypeus except for a median spot reaching 

 its apex, face except at the middle, lower lateral part of frons, narrow 

 hind orbit, front of front coxa, usually the knees narrowly, outside 

 of front tibia, tibial spurs, usually most of first three tarsal segments 

 except at theu* bases and apices, and most of seventh tergite, white; 

 tegula brown ; wings hyaline, their apices infuscate, the forewing with 

 a more or less distinct, short postdiscal fascia centering just beyond 

 the apex of the stigma. 



A distinctive color variant has the black of the femora and tibiae 

 replaced by fulvous, and often the black of the coxae (especially of 

 the front coxa) stained or replaced by fulvous. The type of Prioc- 

 nemis leibyi belongs to this variety. A female of corresponding color 

 has not yet been collected. ||g Another color variation, this one forming 

 a geographic cline, involves the wing color. Male specimens from 

 Florida have the wings, especially the apical half of the forewing, 

 strongly infuscate. This Floridian tendency toward wing darkening 

 is present in a diminishing degree in Lower Austral localities increas- 

 ingly distant from Florida, being still evident in the Lower Austral 

 Zone of North Carolina. 



Female: Forewing 9.5 to 14 mm. long; hind tibia with its dorsal 

 teeth rather weak and the bristles in its dorsolateral row about 0.55 

 as long as the distance between their sockets; last segment of tarsi 

 without preapical bristles beneath. 



Black. Flagellum black; front orbit usually with narrow fulvous 

 stain; wings blackish, the forewing with faintly darkened cross-bands 

 at the apex, just beyond the apex of the stigma, and along the basal 

 vein and nervulus ; hind wing a little paler than the fore wing, darkened 

 apically. 



Females from the Lower Austral Zone tend to have the wings a little 

 darker than females from the Upper Austral and Transition Zones. 



Specimens (55 cf, 849): From Alabama (Spring Hill); Connecticut 

 (Colebrook and East Hartford); District of Columbia; Florida 

 (Brevard County, Buena Vista, Citrus County, Larkins, Ocala, 

 Orange County, Orlando, St. Johns River, St. Nicholas, and Tarpon 

 Springs); Georgia (Alma and Atlanta); Iowa (Sioux City); Kansas 

 (Baldwin, Douglas County, Leavenworth County, Manhattan, Onaga, 

 and Randolph); Louisiana (Shreveport) ; Maryland (Cabin John, 

 Glen Echo, Maj^o Beach, Plummers Island, and Takoma Park); 

 Massachusetts (Boston and South Natick); Michigan (Cheboygan and 

 Newaygo County); New Hampshire (Alton, Belknap Count}^, and 

 Pelham) ; New Jersey (Chatsworth, Fort Lee, and Moorestown) ; New 



