the Dipterous Genus Olbiogaster, O.-S. 503 



tip of the hind tibiee and the distal joints of all the tarsi 

 blackish. 



In Williston's figure the vein R 2+3 (second longitudinal) 

 is represented as terminating in Rj (first longitudinal) just 

 before the tip of the latter, while Osten-Sacken describes both 

 these veins as terminating in the same point in the costa, and 

 presumably on this account he named his species 0. cognatus. 

 An examination of the types of the two species in the British 

 Museum, however, shows that both these statements are 

 incorrect ; in reality, R 2+ 3 terminates in the costa distinctly 

 beyond the tip of R ls as figured by Philippi in the nearly 

 allied (and possibly identical) genus Lobogaster. Williston 

 also incorrectly represents the upper two of the three veins 

 arising from the discal cell as springing from the same point, 

 while he omits the M-Cu cross-vein, which is really quite 

 distinct, and shows Cu 2 as being slightly arched upwards 

 instead of downwards. All these points combine to give 

 quite a wrong idea of the venation, which is really very 

 litile different from that of Lobogaster. Neither Osten- 

 Sacken nor Williston mentions the fact that the costal vein, 

 instead of terminating as in Bhgphus at the tip of R 4+5 

 (third longitudinal), extends about halfway from that point 

 to the tip of M x . 



2. Olbiogaster afrfcanus, s.p. jk 



cJ . Head: Vertex and occiput shining black, with som© 

 not very conspicuous black hair ; front shining black above, 

 dull grey towards the antennae ; clypeus shining dark brown, 

 lighter towards the eye-margins, with some dark hair. 

 Ocelli close together in a nearly equilateral triangle. 

 Antennas in both sexes nearly twice as long as the head and 

 thorax combined, black, the two basal joints reddish yellow ; 

 joints of flagellum about twice as long as broad. Palpi 

 yellowish, the tip of the last joint dark. Thorax: Pro- 

 thoracic lobes yellow ; mesothoracic scutum shining black, 

 except for a narrow yellowish side margin extending from 

 the humeral callus to the base of the wing, sparsely clothed 

 with rather long whitish-yellow hair; scutellum and post- 

 notum blackish. Pleurae shining dark brown, with a large 

 shimmering grey patch. Abdomen black, somewhat shining, 

 with narrow yellow apical margins to segments 1-5, which 

 are narrowest in the middle; pubescence black, except on 

 these yellow bands, where it is white. Segments 6 and 7 

 are somewhat expanded and, like the genitalia, are entirely 

 black,. Legs : Coxae black, the front pair more or less 



