266 DUEHAM DIPTERA. 



XXXIII. 459. 



51 (50). Abdomen dusted; fore femora beneath, besides the 

 fine hairs, with two rather long and strong bristles 

 near the base. ( 2 °33- parva, Mde.) 



Hydrotcea. — Table of European females (Stein). 



(36). Large species, at least 5 mm. 



1 (2). Hinder side of mid tibiae all bristly; eyes thickly 



and long haired. {bezzii, Stein) 



2 (1). Hinder side of mid tibiae with at most 3-4 bristles ; 



eyes bare, or quite short haired. 



3 (25). Knob of halteres black. 



4 (7). Hinder side of mid tibiae, besides the usual bristles, 



with others directed inwards. 



5 (6). Mid tibiae fore side with distinct bristles, the inward 



pointing bristles of the hinder side placed at the 

 beginning of the last third. 



(2028. militaris, Mg.=impexa, Lw.) 



6 (5). Mid tibiae fore side without bristles, the inward point- 



ing bristles of the hinder side placed on or before 

 the middle. (scambus, Ztt.) 



7 (4). Hinder side of mid tibiae with only the usual bristles 



or none. 



8 (14). Mid tibiae outer fore side with at least one distinct 



strong bristle. 

 8a (8b). Fore tibiae outer side without a bristle at the middle. 



(202 7^. pilipes, Stein) 

 8b (8a). Fore tibiae outer side with a bristle at the middle. 



9 (10) (11). Thorax and abdomen shining blue, scarcely 



dusted. (bispinosa, Ztt.) 



10 (9) (11). Thorax yellow-grey with undefined dorsal stripe 



when viewed from behind. 



(2027. palcestrica, Mg.=rondamY, Mde.) 



11 (9) (10). Thorax black, grey dusted, with the beginning of 



two central dorsal stripes in front. 

 12(13). Squamae whitish ; hind tibiae inner side with two or 

 three bristles. dentipes, F. (2025) 



