Sept., I9I3-] Melander: Synopsis of Diptera. 255 



vein; wings rather narrow. (D. C, Mass., La.,* Wise.,* 111.,* Kans., 

 S. Dak., Tex.,* Col., Wyom.) longipennis Loew. 



34. Four dorsocentrals ; face and cheeks largely or wholly yellow; palpi yel- 



low 33- 



Two or three dorsocentrals ; mesonotum subshining 38. 



35. Basal section of the fifth vein much shorter than the apical section, the 



anterior crossvein before the end of the first vein ; knees not yellow ; 

 thorax opaque pollinose ; three fronto-orbitals ; cheeks one third the 

 eye-height; antennae infuscated above. (Eur.;* Id.,* Wash.*) 



perpusilla Meigen. 

 Sections of the fifth vein subequal ; knees conspicuously yellow 36. 



36. Third and fourth veins strongly diverging at the tip, veins brown ; meso- 



notum rather densely whitish-gray pruinose ; lower half of the frontal 



vitta yellow. 2.5 mm. (Col.) pruinosa Coquillett. 



Third and fourth veins parallel, their tips but little diverging ; front mostly 

 yellow 37. 



37. Front yellow, a central spot sometimes blackened; mesonotum subshining; 



veins rather weak ; three fronto-orbitals ; cheeks one sixth the eye- 

 height ; antennas more or less infuscated, the arista black. (D. C, 

 Mass., La.,* 111.,* Wise.,* Kans., S. Dak., Tex., Col., Wyom.) 



longipennis Loew. 



Front yellow ; mesonotum opaque pollinose ; veins brown ; four to six 



fronto-orbitals ; cheeks one third the eye-height ; antennae pale yellow, 



the arista yellow at the base. (Alaska.) pollinosa n. sp. 



38. Front narrow, uniformly brownish or black ; face and cheeks black ; third 



antennal joint minute ; hairs of the mesonotum arranged in rows ; 

 wings broad, the segments of the fifth vein 3:2. (D. C, N. J., Mass.,* 



Ont., La.,* Kans., S. Dak.,* Tex.*) parvicornis Loew. 



Front black above, yellow below; face and cheeks yellow 39- 



39. Tarsi black, sometimes the metatarsi yellowish ; acrostichal hairs in rows ; 



hairs of calypteres dusky ; four fronto-orbitals ; basal section of the 

 fifth vein longer than the apical section. (Eur. ; Id.,* Wash.*) 



sulphuriceps Strobl. 



Metatarsi yellow; hairs of mesonotum irregularly placed; sections of the 



fifth vein subequal. (D. C.) varifrons Coquillett. 



40. Front above lunule mostly or entirely black ; face black ; fringe of calypteres 



white; legs black; antennae black. (In superciliosa the calypteres 



have a dark fringe.) 4'- 



Front largely or wholly yellow ; usually the face and always the cheeks 

 yellow 48. 



41. Side stripes of the thorax broadly yellow; scutelhun, upper pleurae, rear of 



mesonotum, and base of abdomen, yellow 42. 



Yellow stripes of thorax narrower; almost entirely black species 43. 



42. Mesonotum opaque ; sections of the fifth vein equal ; frontal lunule yellow ; 



costa ending at third vein. (S. Am., W. Ind.) 



xanthophora Sehiner, Williston. 



