DURHAM DIPTERA. 265 



XXXIII. 459. 



33 (30). Outer fore side of mid tibiae without strong bristles. 



34 (35). Praesutural acrostichal bristles distinct and strong. 



(2026. stmilis, Mde.) 



35 (34). Praesutural acrostichal bristles absent, or scarcely dis- 



tinguishable from the fine hairs. 



36 (37). Abdomen partly shining dark blue ; the whole length 



of the fore and hind side of mid tibiae shaggy 

 haired. (2028^. tuberadata, Rnd.) 



37 (36). Abdomen otherwise coloured ; mid tibiae not shaggy 



haired. 



38 (39). Mid metatarsus padded with hairs. 



2023. Hydrotcea irritans, F. (^=.denttmana, Mg.) 

 Very common. 



39 (38). Mid metatarsus simple. 



40 (41). Fore femora beneath, near the tip, with short blunt 



teeth. (2029. velutina, Dsv.) 



41 (40). Fore femora beneath with long and sharp teeth. 



42 (43). Squamae brownish yellow ; abdomen rather dark, with 



a scarcely perceptible dorsal stripe. 



(2030. meteorica, L.) 



43 (42). Squamae whitish ; abdomen bluish or greenish-grey 



dusted, with a distinct dorsal stripe. 



(2030^. cinerea, Dsv.) 



44 (2). Abdomen distinctly translucent yellow at the base. 



45 (46). Mid femora beneath with four distant bristles. 



(2021. curvifies, Fin.) 



46 (45). Mid femora beneath near the base with tuft-like 



crowded strong bristles. 



47 (48). Hind tibiae inner side near the tip with a tuft of about 



five strong hairs. (pellucens, Portsch.) 



48 (47). The tuft on the inner side of the hind tibiae placed 



about the middle, and forming a band of numerous 

 strong hairs. {boritssica, Stein) 



49 (1). Small species, at most 3 mm. 



50 (51). Shining black ; abdomen scarcely dusted ; fore femora 



beneath very fine haired. (2034. glabricula, Fin.) 



