On the. B<)i1>ijliid Fauna of South Africa (Diptera). 151 



24 (2.3). The above-named vein short and straight. 



25 (26). Metapleural tuft entirely reddish ; discoidal cell not dilated at end ; 



liasal joints of antennae black ; abdomen of male with silvery lateral 

 patches . .... dimidiata, Macq. 



l'(J (-25). Metapleural tuft entirely black; discoidal cell dilated at end and 

 appendiculate ; antennae red at base; abdomen not silvery. 



dilatata, sp. nov. 



27 (4) . Wings not properly dimidiate, even if the costa is infuscated or striped. 



28 (37). Abdomen of conical shape, pointed at end, very often red ; terminal 



vein of discoidal cell short, straight, but placed obliquely, and there- 

 fore the upper angle of discoidal cell is an acute one (punctulata. 

 group). ' 



29 (30) . Front tibiae distinctly spinulose ; wings with a brown fore-border 



and with dark spots on cross-veins and bifurcations. 



punctulata, Macq. 



30 (29). Front tibiae smooth ; wings without such a pattern. 



31 (34). Wings with a broad brown fore border. 



32 (33). Dark fore border less intensive and less denned, extending to the 2nd 



basal cell and on a part of the discoidal cell . parvula, nom. nov. 



33 (32). Brown fore border well denned, not extending to the discoidal cell or 



2nd basal cell . .... stannusi, Bezzi. 



34 (31). Wings with a narrow, yellowish, or brownish fore-border. 



35 (36). Basal joints of antennae and legs entirely black ; cross- veins infus- 



cated, abdomen red on the sides . . . inaequalipes, Loew. 



36 (35). Basal joints of antennae and legs red ; cross-veins less infuscated; 



abdomen broadly or wholly red . . . batrachoides, Bezzi. 



37 (28). Abdomen not conical and mainly black ; terminal vein of discoidal 



cell straight and perpendicular, its upper angle therefore not acute, 

 the cell being truncate outwardly. 



38 (39). Wings with broad and well-defined black spots on cross- veins and 



bifurcations (balioptera-group) ' . . . balioptera, Loew. 



39 (38). Wings not punctate, or only with less defined shading on the cross- 



veins (Zrasiris-group) .... luteicosta, Bezzi. 



40 (1). Wings entirely hyaline, without any distinct dark pattern (stupida- 



group) ..... parvicellula, sp. nov. 



A. GROUP PUSILLA. 



This small group, which is made distinct by the presence of hyaline 

 feuestrae in the dark part of the wings, included only the West 

 African species pusilla, Macq., and jacchoides, Bezzi. A third South 

 African species is now added to it. 



EXOPROSOPA (EXOPROSOPA) FORMOSULA, sp. uov. 



An elegant species very distinct from all the other South African 

 species of the present subgenus on account of its hyaline feuestrae in 

 the black part of the wings. 



