DURHAM DIPTERA. 311 



XXXVI. 506. 



18 (18a). These bristles very strong and very numerous. 



(gigantea, Mg.) 

 18a (18). These bristles neither strong nor numerous. 



{hisfianica, Lw.) 



19 (17). Mid femora without strong bristles on the underside. 



20 (21). Small yellow species ; wings clear with strong clouds 



at the ends of the long veins. (2258. flava, Mg.) 



21 (20). Larger and darker species ; wings brownish with only 



indistinct clouds at the ends of the long veins. 



(2257. affinis, Mg.) 



22 (16). Arista rather short plumed. 



23 (24). A black spot on V.4 3 . {bistrigata, Mg.) 



24 (23). V.4 3 without any black spot. 



25 (28). Wing tip without the vein-ends clouded. 



26 (27). Costal spines long. pallida, Fin. (2265 below) 



27 (26). Costal spines very short. 



zetterstedti, Lw. (2264 below) 



28 (25). Wing tip with the vein-ends-clouded. 



29 (30). Frons all dull. 



2259. Helomyza similis, Mg. 

 Wearhead, Harperley, 5 $, April- August, 1901. 



30 (29). Frons shining. 



2260. Helomyza Icevifrons, Lw. 

 Harperley, 1 $, April, 1900; Shull, 2 ?, September, 

 1900. 



31 (15). Arista very short haired or pubescent. 



32 (43). Arista distinctly haired. 



33 (38). Ends of the long veins distinctly clouded. 



34 (35). Scutellum very hairy. (univittata, v. Rossi.) 



35 (34). Scutellum almost quite bare except the usual bristles. 



36 (37). A dark spot between the antennas and the eyes. 



2262. Helomyza ustulata, Mg. 

 Bishop Auckland, 1 $, 9th March, 1901. Very rare. 

 I gave the specimen to Mr. Verrall. 



37 (36). No spot between antennas and eyes, (fiilimana, Lw.) 



