Occasional Papers of the Museum of Zoology 3 



Gonomyia (Gonomyia) bidentata, sp.n. 



Allied to G. suhcincrea Osten Sacken ; rostrum orange ; tho- 

 racic pleura with a brown spot on the mesepistenium ; halteres 

 elongate ; wings long and narrow, cell 2nd A narrow ; male 

 hypopygium with the dorsal pleural appendage terminating in 

 a chitinized blade that is bidentate apically; gonapophyses 

 slender, straight. 



Male. — Length, 4.2 to 4.5 mm. ; wing, 5.5 to 5.6 mm. 



Female. — Length, 4.8 to 5 mm. ; wing, 5.4 to 5.6 mm. 



Rostrum orange ; palpi dark brown. Antennae dark brown 

 throughout. Head gray, the occiput paler. 



Pronotum obscure yellow, the scutellum brownish medially. 

 Mesonotal praescutum obscure yellow with three nearly con- 

 fluent dark brown stripes ; pseudosutural foveae conspicuous ; 

 scutum brown, obscure yellow medially and laterally; scutel- 

 lum brown, the posterior margin obscure yellow ; postnotum 

 brown medially, the lateral sclerites yellowish. Pleura yellow, 

 whitish pollinose; propleura darkened; an incomplete, dorsal, 

 longitudinal brown stripe indicated as a more or less conspicu- 

 ous spot on the mesepisternum; a less distinct darkening on 

 the mesostemum, the pale area between these two latter 

 appearing as a white stripe. Halteres very elongate, dark 

 brown, the extreme bases pale. Legs with the coxae whitish 

 yellow ; trochanters yellow ; remainder of the legs brown. 

 Wings grayish subhyaline, highly iridescent; stigma pale 

 brown ; veins dark brown. Wings long, strongly narrowed 

 basally. Venation: Sci ending about opposite or just beyond 

 the origin of Rs, Sc2 close to the tip of Sci, its position 

 slightly variable; basal deflection of R4-\-5 very short to 

 entirely obliterated; cell ist M2 closed; basal deflection of 



