. 46 DIPTERA OF NORTH AMERICA. [PART in. 



Such is a group of chjsely related African species, which I unite 

 in the genus Ardelio. The lateral portions of their face are 

 distinctly broader than in Rivellia, the eyes not so high, and the 

 cheeks, for this reason, broader; the clypeus is narrower and the 

 thorax more strongly developed ; theconvex scutellum has four 

 bristles, like Rivellia. They almost show more affinity to Platy- 

 stoma than to Rivellia; all the species known to me are black, 

 with longitudinal lines of white dust on the thorax, and their 

 wings have black crossbands, between which, along the costal 

 margin, there are black spots or streaks. The single species 

 show, in the length of the third antennal joint, still more con- 

 siderable variations than the species of Rivellia, and it almost ' 

 seems that, in this respect, they might be divided in two sections, 

 one of which would be represented, as a type, by Ardelio longi- 

 pennis Lw., the other by A. brevicornis Lw. 



The genus Epicausta, established by me for two African spe- 

 cies, is less allied to Rivellia than to Stenopterina, which will 

 be discussed below. These species are like Stenopterina in their 

 stature, but are not so slender ; the head is. not unlike that of the 

 species of Dacus proper ; the antenna? are not quite as long as 

 in Stenopterina; the fore coxae are much shorter, and not so 

 movable ; the thorax, seen from the side, is not attenuated in 

 front, as is the case with Steyiopterina ; the scutellum has four 

 bristles, as in the latter genus ; the wings are conspicuously 

 shorter, and the last section of the fourth' longitudinal vein is 

 much more bent forward. The small crossvein is not oblique, 

 as in all Stenopterinse, but perpendicular. The picture of the 

 wings, in both of the species known to me, consists only in a 

 large black spot at the tip. 



Stenopterina, a genus proposed by Macquart in the Suites d 

 Buff on, is well founded, as long as it is confined to the species 

 of the immediate relationship of Dacus brevicornis Fab. and 

 seneus Wied. Unfortunately the same author, in the Dipteres 

 Exoliques, has entirely left out of sight the characters of this 

 genu;;, established by himself, and has introduced in it a number 

 of heterogeneous forms, and, at the same time, placed in the 

 genus Herina species which either belong to Stenopterina or 

 are more closely related to it than to any other genus. His 

 Stenopterina femorata and immaculata, both from Bourbon, 

 seem to belong rather to Epicausta than to Stenopterina; 



