DURHAM DIPTERA. 267 



XXXIII. 459. 



13 (12). Squamae yellow ; hind tibiae inner side with 4-6 



bristles. (2026. similis, Mde.) 



14 (8). Mid tibiae outer fore side without bristles. 



15 (18). Ocellar triangle shining black. 



16 (17). Thorax shining blue-black. {tuberculata, Rnd.) 



17 (16). Thorax grey-black, dull. occulta, Mg. (2020) 



18 (15). Ocellar triangle thickly grey dusted, at least not con- 



spicuously shining. 



19 (20). Hind tibiae inner fore side with 4-5 bristles ; large 



species. (2022. cyrtoneurina, Ztt.) 



20 (19). Hind tibiae inner fore side with at most two bristles. 



21 (22). Thorax black, scarcely dusted ; frons above the* 



antennae narrower than the diameter of the eyes at 

 the same place ; praealar bristles small but distinct. 



(2029. velutina, Dsv.) 



22 (21). Thorax thickly grey dusted; frons above the antennae 



as broad or broader than the diameter of the eyes; 

 praealar bristles absent or scarcely visible. 



23 (24). Arista distinctly pubescent where thickest ; hind 



tibiae with three bristles, one directed inwards, 

 one large and one smaller outwards. 



(2030. meteorica, L.) 



24 (23). Arista entirely bare. The bristles on the outer side 



of the hind tibiae absent. (2031. armipes, Fin.) 



25 (3). Knob of halteres yellow, sometimes brown, but never 



black. 



26 (27). Shining black thorax, except for the strong bristles 



almost entirely bare. (2019. ciliata, F.) 



27 (26). Colour not shining blue-black; thorax distinctly short 



haired in addition to the strong bristles. 



28 (29). Hind tibiae with two outer bristles ; abdomen with 



two shining spots on the second ring. 



(pandelli, Stein) 



29 (28). Hind tibiae with one outer bristle ; abdomen without 



any shining spots. 



30 (31). Abdomen more or less yellow at the base ; praesutural 



acrostichal bristles absent. (2021. curvipes, Fin.) 



