DURHAM DIPTERA. 37 1 



LI. 639. 



7 (6) (8). Legs black ; tarsi pale. 



2719. Oscinis frit, L. 

 Escomb, 1 ?, June, 1899. 



8 (6) (7). Legs black ; fore tibiae, and all the tarsi except the 



last joint, yellow. (2720. pusilla, Mg.) 



9 (3). Arista white with the base black. 



10 (11). Legs black; tarsi pale; halteres whitish. 



(2717. maura, Fin.) 



11 (10). Legs all black; halteres blackish. 



(2716. albiseta, Mg.) 



12 (2). Body grey ; head with at least the frons pale. 



13 (16). Head black, except narrowly pale behind the antennae ; 



vertical triangle grey. 



14 (15). Legs black; base and tip of the tibiae, and all the 



tarsi, except the last joint, yellowish, (nana, Ztt.) 



15 (14). Legs wholly black. {nigripes, Ztt.) 



16 (13). Head yellowish white ; vertical triangle grey. 



(albipalpis, Mg.) 



17 (1). Antennae either wholly or partly yellow. 



18 (19). Body wholly black. (frontella, Fin.) 



19 (18). Body with at least the thorax grey or pale. 



20 (23). Dorsum grey, with three longitudinal grooves. 



21 (22). Legs all yellow. (lineella, Fin.) 



22 (21). Legs yellow; coxae and femora dark, (sulcella, Ztt.) 



23 (20). Dorsum not grooved, smooth. 



24 (32). Thorax grey, without yellow marks. 



25 (26). Dorsum with three narrow dark stripes ; abdomen 



all greyish black. (annultfera, Ztt.) 



26 (25). Dorsum not striped. 



27 (30) (31). Abdomen all dark, shining. 



28 (29). Wings longer than the abdomen ; arista yellow. 



(sordt'della, Ztt.) 



29 (28). Wings shorter than the abdomen ; arista black. 



{brachyptera, Ztt.) 



30 (27) (31). Abdomen with two yellow bands, (cinctella, Ztt.) 



31 (27) (30). Abdomen wholly yellow. (abdominalis, Ztt.) 



32 (24). Thorax yellow with black marks. 



