174 [July, 



3 (26). Mesopleurae bristly. 



4 (21). Halteres black or brown (verralli and ciliataj. 



5 (16). Hind tibice bare (affinis and serrata), or cilia small and jiumerous. 



6 (7). Costa plainly to middle of wing 1^ mm. a.rmata. 



7 (6). Costa plainly sliori of middle. 



8 (9). Abdomen in both sexes narrowly but conspicuously banded irith white on 



hind margins of segments about 1 mm. Verralli. 



9 (8). Abdomen not so banded; the hind margins in serrata are piale but not 



white. 

 10 (11). Mesopleurse with one bristle much longer than the others. Anal organ very 

 large, as long as the last abdominal segment... ahont f mm. spinata. 



Bristles of nearly uniform size. 



Fore metatarsi distinctly thickened, in both sexes, being as wide as the 

 tibice or nearly so ^ nxm. crassipes. 



Metatarsi simple, or whole tarsus slightly thickened (latifrons) 



A group of five or six short hairs underneath the hypopygium on each side. 

 Upper supra-a,nte7inal bristles outside an alignment with inner bristles 

 of middle frontal row f mm. latifrons. 



No such group of bristles, fiuxtra-antennal bristles only in such align- 

 ment and not outside it l-^ mm. affinis. 



Tibias plainly (rudis) or very strongly (ciliata and major) ciliated. All 

 three species have one pleiiral bristle much longer than the 

 others. 

 17 (18). Frons quite dull. Upper supra-antennal bristles outside an alignment 

 with inner bristles of middle frontal row. Hypopygium large, with a 

 conspicuous bristle on each side beneath 1-1? mm. rudis. 



Frons more or loss shining. Supra-antennal bristles inside such align- 

 ment. Hypopygium small or moderate, and bare. 



Costa fine and delicate. Fourth abdominal segment of female abbreviated. 

 Fore coxae clear yellow 1-lf mm. ciliata, Zett, 



Costa of the usual stoutness. Abdominal segment not abbreviated. Fore 

 coxse dusky yellow about 2 mm. major. 



Halteres yellow. 



Frons black and shining. A deep black insect, closely allied to ciliata, but 

 wanting the abbreviated abdominal segment 1-1:^ mm. eequalis. 



Frons grey and dull. Pale or yellowish species. 



Costa well beyond middle of wing. One of the pleural bHstles much 



longer than the others. A large species 1^2 m.m. flavescens. 



25 (24). Costa well short of the middle. The bristles all small. A small species. 



... 1 mm. pallens. 

 Mesopleuras bare. 



Halteres black. 



Frons highly glossy (pa.rva, mallochi, glabrifrons and propingua) or at 



least somewhat shining {longiseta and longipalpis). 



Costa distinctly less than half the wing length. 



Male palpi very large and a Imost bare f mm. longipalpis. 



Male palpi normal. 



