DURHAM DIPTERA. 263 



XXXIII. 459. 



459. Hydrot^ea, Dsv. 



Full descriptions of the British species by Mr. Percy H. 

 Grimshaw will be found in the E.M.M., Oct.-Nov., &c, 1905. 



Table of European males according to Herr P. Stein, 1903. 



1 (49). Large species, at least 5 mm. 



2 (44). Abdomen nowhere translucent yellow. 



3 (12). Eyes thickly hairy. 



4 (7). Hind femora beneath with a thorn formed of two 



bristles pointing straight downwards. 



5 (6). The thorn at the middle of the hind femora. 



(2019. ciliata, F.) 



6 (5). The thorn near the base of the hind femora. 



2020. Hydrotcea occulta, Mg. 

 Bishop Auckland, 6 $, May-August, 1900. 



7 (4). Hind femora without any thorn beneath. 



8 (9). The inner side of the hind tibia? with an erect tuft of 



long hairs ; halteres yellow. (penicillata, Rnd.) 



9 (8). Inner side of hind tibiae without tuft ; halteres black. 



10 (11). Outer fore side of mid tibiae with two strong bristles; 



hinder side with a row of bristles. (bezzi, Stein) 



11 (10). Outer fore side of mid tibiae without bristles ; hinder 



side with two bristles. (2022. cyrtoneurina, Ztt.) 



12 (3). Eyes bare, or at most pubescent. 



13 (20). Eyes more or less distinctly separated on the vertex. 



14 (17). Outer fore side of mid tibiae with one or two prominent 



bristles. 



15 (16). Hinder side of mid coxae with three close-lying 



depressed bristles, which together appear like a 

 strong thorn. 



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



16 (15). Mid coxae without bristles. {bispinosa, Ztt.) 



17 (14). Outer fore side of mid tibiae without bristles, at most 



with fine hairs. 



