1912.] ]79 



50 (1). Mesopleurae hare. 



51 (52). Cilia on middle and hind tihise irregular in di-itrihution and placed on 



both sides the seam 3 mm. melanocephala, v. Ros. 



52 (51). Cilia of regular distribution and placed onlt/ on the inner side of the 



seam. 



53 (62). Costa of female swollen. 



54 (57). Costa greatlg swollen, encroaching on coital cells, and partiaVg oblitera- 



ting the first thin vein. Thorax pale. 



55 (56). Costal swelling stops well short of the inner branch of the second thick 



rein If ram. costalis, v. Ros. 



56 (55). Costal swelling extends to end of the co-tta...2 mm. brunneipennis, Costa. 



57 (54). Costal swelling comparativelg slight and not encroaching on costal cells. 



Thorax dark. 



58 (59). Halteres and legs yellow. Anal organ of ordinary size. 



...1-1^ mm. suhtumida. 



59 (58). Halteres and legs dark. Anal organ minute. 



60 (61). Costa conspicuously stooUen, almost humped ; fringe only moderately 



long. A moderate-sized species 1^-H mm. denotata. 



61 (60). Costa not conspicuously swollen {may be overlooked in unfavourable 



positions of the wing) ; fringe very long. A full-sized species 



...1^-2 mm. tiimida. 



62 (53). Costa not swollen. 



63 (92), Costa long — at least to toing middle or nearly, very commonly beyond 



In derasa the costa of the male is occasionally somewhat short. 



64 (73). Halteres black or brown, sometimes dusky yellow {angusta, var.). 



65 (66). Tibial cilia large and sparse. 



A large species with dark legs, f oiu* large and equal siipra-antennal 

 bristles, the upper ones oiitside an alignment with inner bristles of 

 middle frontal row, and with the first costal division shorter than the 

 other two . 2 mm. frontalis. 



66 (65). Cilia very weak and numerous, or tibise quite bare [rubescens). 



67 (68). Anal oryan minute. A very small species. 



Hjrpopygium very large with small erect hairs on the sides and a 

 coiiple of bristles, one above the other, on each side... J mm. discreta, 



68 (67). Anal organ not minute, nor the species very small. 



69 (70). Halteres yellowish brown. Thorax dusky red. Hypopygium with a 



bunch of bristles on each side. Costal fringe only moderately long. 



...If mm. rubescens. 



70 (69). Halteres and thorax black. Hypopygium without such bristles. Fringe 



long. 



71 (72). First costal division much longer than the second, generally twice as long, 



A large species 1^-2} mm. fusca. 



72 (71). First costal division not longer or only slightly longer than the second 



the venation being the same as in subtumida. Not a large species. 



...\\ mm. more or less, angusta. 



73 (64). Halteres yellow. 



2 O 



