284 DURHAM DIPTERA. 



XXXIII. 474. 



14 (17). Mid tibiae outer front side with several bristles. 



15 (16). Orbits in spite of the dusting very distinctly shining; 



mid tibiae inner side with only one fine bristle. 



(iiitida, Stein) 



16 (15). Orbits not shining; mid tibiae inner side with two 



strong bristles. (2156. polychceta, Stein) 



17 (14). Mid tibiae outer front side with only one bristle. 



18 (19). Legs entirely black; hind tibiae outer front side with 



a row of equally long little bristles. 



coracina, Lw. (2147) 



19 (18). Knees more or less yellow. 



20(21). Fore tibiae outer side with one fine bristle; mid 

 femora beneath at the base with a remarkably 

 long hair-like bristle. (2 161. genitalis, Stein) 



21 (20). Fore tibiae without bristles ; mid femora without the 



above bristle. {tuberculata, Ztt.) 



22 (11). Mid tibiae inner side without any bristle. 



23 (34). Squamae rather small ; scales of equal size. 



24 (25) Eyes shortly but thickly and distinctly haired. 



{hirticeps, Stein) 



25 (24). Eyes bare, or at most pubescent. 



26 (27). Orbits lead-grey, faintly but perceptibly shining. 



serena, Fin. (2154) 



27 (26). Orbits not in the least shining. 



28 (31). All knees, especially the fore knees, distinctly yellow ; 



mid sized species, 4^-5^ mm. 



29 (30). Mid tibiae outer front side with two bristles. 



(2148. kowarzii, Verr.) 



30 (29). Mid tibiae outer front side with one bristle. 



(2151. sociella, Ztt.) or (2152. similis, Stein) 



31 (28). At most the fore knees indistinctly yellow ; smaller 



species, 3-4 mm. 



32 (33). Frontal stripe at its smallest place always somewhat 



wider than the orbits ; mid femora beneath at the 



base with a fine bristle ; dark grey species. 



aerea, Ztt. (2145) 



33 (32). Frontal stripe at its smallest place at most as wide as 



the orbits ; mid femora beneath at the base without 

 bristles; brown-grey species. (2153. parva, Stein) 



