ou SYUPIIIDJF:. 



5 (2) Pterostiguia with the base black or blackish ; 



face grey-dusted ; peristoma usually war- 

 row and almost entirely black ; third 

 longitudinal vein always straight. 

 G (7) Third antennal joint very elongate, as long 

 as the arista, much swollen and pointed 

 at the end ; basal joint of hind tarsi 

 distinctly swollen ittflaticornisj sp. n. 



7 (6) Third antennal joint much shorter than the 



arista; basal joint of hind tarsi not 

 swollen. 



8 (13) Third abdominal segment with a move or 



less broad yellow band, which reaches 

 the anterior border. 



9 (12) Peristoma very narrow and black; second 



and fourth abdominal segments each with 

 a yellow band ; front femora yellow, with 

 blackened base. 



10 (11) Wiogs entirely hyaline; yellow band of 



second segment narrow adliyatus, Wied. 



11 (10) Wings with the basal half infuscated : yel- 



low band of second segment broader .... var. tricolor, Walk. 



12 (9) Peristoma broader, with distinct black 



lateral stripe ; second and fourth segments 

 without yellow band ; front femora 

 black var. melas, A ar. n. 



13 (8) Band of the third segment whitish, not 



broader than the others and distant from 

 the anterior border. 



14 (15) Thorax shining ; wings pure hyaline ; 



femora yellow, blackened at base ; face 

 white pilose ; abdomen with four distinct 

 bands claripennis, Loew. 



15 (14) Thorax dullish ; wings faintly infuscated, 



pubescent ; femora black ; face black 

 pilose ; abdomen with three less distinct 



bands hirticeps, Loew. 



l(j (1) Eyes bare ; postocular fringe short and 

 sparse ; antennae yellow, or rarely dark- 

 ened above, the third joint short and 

 rounded. 



17 (18) Abdomen oval, the second segment with a 



yellow spot on each side, the third and 

 fourth with a broad yellow transverse 

 band, which is slightly emarginate be- 

 hind cognatus, Loew. 



18 (17) Abdomen pnrallel-sided, narrow, and linear. 

 19(20) Face wholly yellow; abdomen entirely 



yellow, except base and three very narrow- 

 black stripes on hind bolder of second, 

 third and fcurth segments, which are 



sometime s duplicated trisectiis, Loew. 



20 (19) Face with a median black stripe ; abdomen 

 wholly black, with three pairs of } T ellow 

 oblique spots, those on third and fourth 

 segments in contact in the middle rediviciis, sp. n. 



