134 DURHAM DIPTERA. 



XXIV. 



72 (78). Antennae as long or nearly as long as the body, first 



joint cylindrical, three times as long as broad, 

 third joint exceedingly long and thin (III. 36), 

 hind coxae with two black bristles. 



236. Raphium, Mg. (1286. longicorne, Fin.) 



73 (72). Antennae moderately long, hind coxae without any 



distinct black bristle (except in P. mucins). 



Porphyrops, Mg. (237) 



74 (71). Small slender species, 2-3 mm. Under half of the 



posterior orbit thickly haired, third antennal joint 

 very long, hind coxae with one black bristle. 



XlPHANDRIUM, Lw. (240) 



75 (62). Third antennal joint short and broad, as broad or 



broader than long (III. 35, 37). 



76 (79). Legs long and thin, almost bare, X.5, much beyond 



the middle of the wing (V. 15), V.6. absent or 

 weak. Acrostichal bristles in two rows. Mostly 

 greyish or yellow species. 



77 (78). Third antennal joint ovate, pointed, arista subapical, 



hind femora with the praeapical bristle distinct, 

 male organ not prominent. Achalcus, Lh. (241) 



78 (77). Third antennal joint short and rounded, arista apical 



(III. 37), praeapical bristle absent on hind femora, 



male organ long, distinct, and free. 



Medeterus, Fisch. (242) 



79 (76). Legs short and rather strong, usually hairy. X.5, 



not beyond the middle of the wing. Metallic 

 green or blue species, sometimes partly yellow. 



80 (81). Acrostichal bristles absent, legs almost bare, a large 



impression in front of the scutellum, body partly 

 yellow. Chrysotimus, Lw. (252) 



81 (80). Acrostichal bristles in two rows, no impression before 



the scutellum, body metallic green or blue. 



82 (88). Thoracic bristles yellow, legs almost bare, male organ 



large and free, very small species. 



235. Thrypticus, Gerst. (1285. bellus, Lw.) 



83 (82). Thoracic bristles black, legs bristly, male organ 



small. Chrysotus, Mg. (230) 



