NORTH AMERICAN DIPTKRA. 109 



margin. Eyes bare, descending three-fourths or more as low as oral 

 margin. Antennae nearly as long as face, second joint slightly or 

 hardly elongate, third two and one-half to four times as long as 

 second ; arista not long, thickened more than half its length, bare, 

 indistinctly H-jointed, second joint short. Proboscis rather shorter 

 than hight of head, not stout, labella developed ; palpi rather slender, 

 thickened at tip. Thorax narrower than head; scntellum with an 

 apical strongly decussate pair of macrochretse and two lateral pairs. 

 Abdomen elongate oval, not wider than thorax, first segment short- 

 ened ; raacrochaetaj only marginal; hypopygium concealed. Legs 

 slightly bristly; claws and pulvilli short in both sexes. Wings 

 about as long as abdomen, with a pair of costal spines or a single 

 small one, third vein bristly at base; apical cell ending before tip of 

 wing, closed in margin ; fourth vein bent at an angle, with or with- 

 out a wrinkle at bend, apical cross-vein strongly concave ; hind cr().«s- 

 vein nearly straight, a little nearer to bend of fouith vein. Type. 

 G. polita n. sp. 



Oyiiinoprosopa polila n. sp. 9.— Eyes brown, frontal vitta brownish 

 orange, sides of front, face and clieeks pure silvery white : anterior pair of ocellar 

 bristles strongest, directed forward and outward ; antennae and arista blackish, 

 first two antennal joints more or less rufous, second somewhat elongate and with 

 a bristle on front edge, third hardly three times as long as second ; prohos<^is 

 black, palpi yellow ; occiput cinereous, sparsely short black-bristly. Thorax 

 silvery, with three blackish vittaj, the outer ones heavy, the middle one narrow, 

 all. reaching about to scutelium; scutellum silvery. Abdomen deep shining 

 black, segments two to four silvery white at base; first segment without macro- 

 chfette, second with a lateral one and a median marginal pair, thiitd and fourth 

 each with a marginal row of eight or more raacrochajtse. Legs black, femora 

 and tibifB bristly, front femora silvery on outside ; pulvilli small, whitish. Wings 

 smoky-hyaline, more infuscated on costal portion, with a pair of costal spines, 

 fourth vein with a wrinkle at bend; tegulse pure white, halteres brownish yel- 

 low. Length of body 4.5 mm. ; of wing 3.5 mm. 



Described from one specimen; So. Florida (Chas. Koljcrtson). 



Gyiiinopro»«o|»a arg«'iililroiis u. sp. %. — Differs as follows from G. 

 polita: Front, face and cheeks, iucluding frontal vitta, all silvery white, the 

 vitta in some lights having a slightly different shade ; antennse entirely blackish, 

 second joint hardly at all rufous, third joint about four times as long as second ; 

 vittse and macrocha?t{e about same; claws and pulvilli slightly elong-ate. hypo- 

 pygium black. Wings with only one costal spine, distinctly infuscated, fourth 

 vein without wrinkle at bend, but perhaps with a very slight stump; tegulse 

 white, halteres pale yellowish. Length of body 4 mm. ; of wing nearly 3 mm. 



Described from one specimen ; 80. Florida (Chas. Robertson). 



GyiiiiioproKitpa t'larilVoiis n. sp. % .—Differs as follows from G. polita : 

 Frontal vitta orange-yellow, slightly silvery pollinose ; antennie blackish, second 



TRANS. AM. ENT. SOC. XIX. MAY, 1892. 



