206 PERCY SLADEN TRUST EXPEDITION 



or three very indistinct darker clouds on the costa. Mediastinal vein i-eaching costa at 

 origin of pnefurca, just before middle of wing, subcostal cross- vein near its tip ; first 

 longitudinal vein ending in costa at about f of wing, marginal cross-vein some distance 

 beyond its tip ; base of submarginal cell, great and small cross- veins forming one obtusely- 

 angulated line at about f of wing ; first posterior cell contracted at apex. Halteres 

 yellow. Ahdunien dark fuscous, with yellow lateral spots on the apices of the segments, 

 almost meeting in the middle ; these spots are smaller and less yellow in the female. 



Length of body 4 nmi. 

 ,, wing 4*5 mm. 



Loc. Seychelles. Mahe : forest behind Trois Freres, 2000 ft., 2 ^, 1 ?. 



I have seen a damaged specimen from Lake Victoria Nyanza, and specimens of a 

 very similar, but distinct, species from Salisbury, Mashonaland. 



Genus Styringomyia Loew, Dipt. Beitr., i. 6 (1845). 

 Idiophlehia Griinberg, Zool. Anz., xxvi. 524 (1903). 

 Pycnocrepis Enderlein, Zool. Jahrb., Syst., xxxii. 65 (1912). 

 17. Stijr'ingomyia mahensis, sp. n. (Plate 11, fig. 8, $ genitalia.) 

 Lutea, mesonoto nigro, antennis fusco-annulatis, pedibus annulis 4 latis nigris ; alis 

 parum infuscatis et nigropunctatis. 



^$. Head yellowish, front bristly, especially in $ ; palpi rather dark, the three apical 

 joints fuscous at their tip ; second and third joints considerably widened apically. 

 AntenncB yellowish, second joint black ; joints of flagellum ovate, with whorls of 

 bristles about their middle, spotted with fuscous, so that the antennae have a ringed 

 appearance. Prothorax fuscous yellowish. Mesothorax blackish above, except for a 

 median yellow stripe behind the suture which extends across the scutellum ; pleurae and 

 sternum clear yellow-ochreous. Legs yellow, rather densely covered with long hairs, and 

 with scattered stronger bristles, with distinct black rings ; four anterior femora with 

 a narrow ring beyond the middle and a broader one just before the apex ; on the hind 

 femora the rings are similar but somewhat more conspicuous, and the anterior one is in the 

 middle. All tibiae with a broad ring before the middle and a narrower one at the apex. 

 Tarsal joints blackish at the tips, and the whole of the last joint is dark (the tips of the 

 tarsal joints are much lighter on the hind legs). Wings slightly infuscated, especially on 

 the 5th longitudinal vein, with purplish reflections ; a blackish spot on the small cross- 

 vein ; the great cross-vein and the apex of the discal cell are marked with blackish, as is 

 the axillary vein towards its tip; this tip is bent downwards to the hind margin almost at 

 a right angle, and a stump of a vein arises from the angle. Halteres yellowish. Abdomen 

 in $ testaceous with narrow fuscous bands on the apices of the segments, in $ mostly 

 blackish (very likely owing to discoloration) ; genital segment in both sexes yellowish. 

 Genitalia of $ similar to those of S. crassicosta ; the large upper lobes bear four terminal- 

 dorsal appendages, of which the inner pair are very long, membranous, and terminated by 

 a long bristle ; the outer pair are much shorter than the corresponding structures in 

 S. crassicosta, being reduced almost to tubercles, but terminated, as in S. crassicosta, by 

 a strong spine. Between the two large lobes, at the base, is a small unpaired structure 



