1904.] 167 



12 (11) Face not extending downwards as low as tlie bottom of the eyes... 



5. Dofichopus Latr. 



13 (10) Basal joint of hind tarsi witlioiit anv bristle above. 



14 (15) Hind femora with a row of erect bristles in front... 



fi. Tachytrechus Stann. 



15 (14) Hind femora without a row of erect bristles in front. 

 Ifi (33) Hind coxfB with only one erect bristle outside. 



17 (28) Hind femora with a preapical bristle. 



18 (25) First posterior cell narrowed towards eml (eonf. Oymn. assimilis). 



19 (20) Arista evidently hairy 7. Poeeifobothnis Mik 



20 (19) Arista not evidently hairy. 



21 (24) Proboscis shorter than head. 



22 (23) Hypopygium sessile 8. ITercostomiis hw. 



23 (22) Hypopygium pedunculate ; basal joint of arista very long... 



9. Mi/pophi/llux Lw. 



24 (21) Proboscis longer than head 10. Ortfwrkile Latr. 



25 (18) First posterior cell not narrowed towards end. 



2fi (27) Thorax without distinct velvetty spots 11. Gymnopternnn Lw. 



27 (2*") Thorax with four black velvetty spots ; third antennal joint pointed and 



hairy 1-. Lamprochromus Mik 



28 (17) Hind femora without a preapical bristle. 



29 (30) Arista subapical ; eyes (J) usually approximated on face, but not on 



frons ; pul villi of front feet short 13. Chrysotus Meig. 



30 (29) Arista distinctly dorsal ; eyes ( S ) not approximated on face, but often so 



on frons ; pulvilli of front feet often elongate. 



31 (32) Wings ovate ; eyes ( ^ ) wide apart on frons 14. Melanosfolus Kow. 



32 (31) Wings narrowed about base ; eyes ( S ) touching, or closely approximated 



on frons 15. Diaphonis Meig. 



33 (16) Hind coxae with more than one erect bristle outside ; species usually with 



glistening silvery appearance. 



34 (35) Basal joint of antenna hairy above \6. Arffi/ra Macq. 



35 (34) Basal joint of antennae quite bare above 17. Letu-ostola Lvr. 



36 (3) Arista apical, or practically so (conf. 13. Chrysotus). 



37 (50) Colour metallic green or blue (some species of Medeterus arc rather 



greenish, but have very short antennae rounded at tip). 



38 (39) Antennte short, rounded at tip ; anal vein absent ; bristles on thorax 



yellow; very small species 18. Thrypticu.i Qerst. 



39 (:i8) Antenna? ( <? ) long, pointed at the tip. 



40 (19) Second antennal joint simple, transverse. 



41 (48) Hypopygium sessile, more or less imbedded, but lamella; (often filiform) 



usually conspicuous. 



42 (43) Hind coxse with two (one large) conspicuous black bristles ; basal joint 



of antenna) cylindrical, nearly three times as long as deep, third joint 

 long and linear in both sexes, not larger at its base than second ; 

 abdomen rather long 19. Rhaphium Meig. 



43 (42) Hind coxed with only one distinct black bristle or with none ; basal joint 



of antenna! not much longer than deep, tliir.l joint larger at its base 

 than second. 



