386 DURHAM DIPTERA. 



LVIL 663. 



5 (4). Palpi of the usual size. 



6 (7). Palpi comparatively narrow, almost threadlike, with 



stout end-bristles in both sexes ; legs stout ; 

 male organ large, shining chestnut-brown ; sixth 

 abdominal segment with strong marginal bristles 

 in the male. (2843. trinervis, Beck.) 



7 (6). Palpi dilated. 



8 (9). Palpi with strong bristles in both sexes ; male organ 



small and matt ; legs long and thin ; costa extend- 

 ing far beyond the wing middle ; wings smoky 

 black. (2842. opaca, Mg.) 



9 (8). Palpi without strong bristles in the male, only finely 



ciliated. 



10 (11). Third antennal joint extraordinarily large in the male, 



almost as large as the eyes ; male organ large, 

 shining black. 



Phora nigrico7-nis, Egg. 

 Bishop Auckland, 1 $, 8-3-02. 



11 (10). Third antennal joint about half as large as the eyes, 



and thinly pubescent ; male organ small ; end half 

 of the costa thickened and very finely ciliated. 



(2844. htgubris, Mg.) 



12 (3). Four distinct thin-veins present. 



13 (48). Halteres yellowish. 



14 (21). V.3. from the base to the fork bristly. 



15(16). The tip third of the wing brown; costa strongly 

 thickened in the female. (2845. thoracica, Mg.) 



16 (15). Wings unicolorous, not browned at the tip. 



17 (20). Costa not thicker at its end half; thorax black. 



18 (19). Hind tibiae with 5-6 bristles ; legs orange with dark 



brown femora and coxae. (2846. urbana, Mg.) 



19 (18). Hind tibiae with only two bristles ; legs red-brown, 



fore legs lighter. (2847. fonm'ca, Beck.) 



20 (17). Costa much thickened on its second half; thorax 



brownish ; legs all yellow ; hind tibiae with four 

 bristles. {thoracica, Mg., var. claripennis) 



21 (14) V.3. not bristly. 



