DURHAM DIPTERA. 1 47 



XXIV. 229. 

 229. Gymnopternus, Lw. 



1 (2). Femora mostly blackish, mid tibiae thickened and 



twisted at the tip in the male, and armed with 

 short recurved thorns. 



1254. Gymnopternus cupreus, Fin. 

 Bedburn, 1 $, August 7, 1902. 



2 (1). Femora yellow, or almost so. 



3 (4). Costa thickened from its base to the end of V.I . 



(1255. celer, Mg.) 



4 (3). Costa normal. 



5 (6). Antennae not wholly black, a little yellow at the base. 



Steel-blue species, 5 mm. (1257. chalybaus, W.) 



6 (6). Antennae wholly black. 



7 (8). Outer appendage of the hypopygium roundish, 



yellow, and yellow haired ; blackish green species, 

 3 mm. (1256. metallicus, Stan.) 



8 (7). Outer appendage of the hypopygium triangular, 



black, and short black haired. 



9 (10). Wings clear, V.4. straight. Face black. 



1258. Gymnopternus cerosus, Fin. 

 Waskerley, 8 $ ; Bishop Auckland, 1 $ , July, 1900-01. 



10 (9). Wings brownish, V.4. bent towards V.3. Face white. 



(1259. assimilis, Staeg.) 



230. Chrysotus, Mg. 



1 (4). Femora all or mostly yellow. 



2 (3). Femora all yellow in the male, or with a central brown 



ring or cloud in the female ; fore coxae black 

 haired; 2J mm. (1261. neglectus, W '.) 



3 (2). Hind femora with the tip sharply black ; fore coxae 



yellow haired; 2 mm. (1262. cilipes, Mg.) 



4 (1). Femora nearly all black. 



5 (8). Hind trochanters and the base of the femora yellow. 



6 (7). Small species ; hind tibiae moderately ciliated. 



(1263. pulchellus, Kow.) 



7 (6). Fair sized species, 2 mm.; hind tibiae strongly 



ciliated. (1263^. fenioratus, Ztt.) 



