86 Mr. F. M. van der Wulp on 



robust than the others ; first tarsal joint as long as the two or three 

 following joints together ; foot-claws long; pulvilli absent. In the 

 wings all the posterior cells are open and not constricted ; the fourth 

 posterior cell issues from the second Ijasal cell ; the third basal cell 

 is closed at the margin of the wing. 



This genus is related to Rkadinus, but differs in the 

 mystax, which does not ascend to the antennae ; the total 

 want of bristles on the thorax and scutellura ; the less ex- 

 cavated front, the more elongate antennse, and the not 

 closed fourth posterior cell. From Leptogaster it differs in 

 the hind legs, which are less elongate and of which the 

 femora and tibiae are not club-shaped, the tibiae being 

 gradually and only slightly enlarged towards the tip.' 



8. Psilinus cinerascens, n. sp. $. 

 (Plate II, fig. 7.) 



Grey ; antennse, incisions and terminal segment of the abdomen, 

 and legs, black. 



Length 8 mm. 



Head (figs. 8 and 9) greyish-white ; mystax yellow ; beard whitish. 

 Antennce, proboscis and palpi black. Thorax and scutellum grey ; 

 thoracic dorsum somewhat brownish-rufous pollinose, with two 

 blackish stripes, which do not reach the hind border, laterally on 

 each side two black spots ; with the exception of a row of fine, 

 yellow, erect hairs before the halteres, the whole thorax is bare. 

 Abdomen cinereous, with blackish incisions ; anal segment a little 

 shorter than the preceding segments, shining black, with four or five 

 very small spines. Legs black, the base of the tibias slightly rufous ; 

 the front coxse, the femora on the underside, the tibia), and tarsi 

 with whitish hairs and bristles. Halteres yellow, proportionately 

 large. Wings greyish hyaline, with black veins ; small cross-vein 

 on the middle of the discal cell. 



A single female specimen from Aden. 



9. Sisyrnodytes hrevis, Macq. 



Acnephalum hrevc^ Macq., Dipt. exot. i, 2, p. 52, Tab. 4, 



f. 3. 

 Sisyrnodytes fioccus, Low, Neue Beitr. zur Kenntn. der 



Dipteren, iv, p. 40. 

 Basypocjon contrarius, Walk., Entomologist, v, p. 257. 



A single female specimen from Aden. 



