92 Annals of the South African Museum. 



small cheeks, which are clothed by dense hairs, dark yellowish above 

 and white below, the latter being the more developed ; beard white. 

 Proboscis entirely black, thin, with small terminal labella, 3-4'5 mm. 

 long ; palpi black, long, the apical joint with short white hairs. Eyes 

 intimately connected. Thorax, scutellum and abdomen deep black, 

 the last a little shining, chiefly at the base of the segments ; they are 

 entirely clothed with dense, soft, equal, rather long white hairs which 

 from a front view have a silky sheen, without any dark bristles, even 

 on the abdomen ; the hairs of the end of the abdomen are narrowly 

 yellowish at the base ; venter with long hairs, but it is concealed under 

 the long hairs of the sides of the tergites. Genitalia black. Squamae 

 white, with yellow border and long white fringe; pleurae densely 

 clothed with grey-dust. The black band of the knob of the halteres 

 is limited to the upper side. Legs entirely black, white-scaled, with 

 the femora white-haired and black-spinose ; middle femora with 2, 

 hind femora with 4-6 spines ; claws black, with a reddish base ; 

 pulvilli dirty yellow. Wings hyaline, iridescent, a little whitish on 

 the basal half and along the fore border, with yellow veins ; base of 

 the costa with a short tuft of silvery hairs; upper branch of the 

 cubital fork a little retreating at base. 



G-ONARTHRUS CYLINDR1CUS, Bezzi (1906). 



Easily distinguished from chioneus, Bezzi, on account of the black 

 abdominal bristles and of the white knob of the halteres. 



Of this widely spread species there is a female specimen from South 

 Ehodesia, Gwelo, April, 1917 (Miss Skaife). 



CBOCIDITJM, Loew (1860). 



This genus is not represented in the collection, but I have received 

 a specimen of the typical species from Willowmore (Cape), and have 

 seen a new species with unspotted wings from the same locality. Its 

 nearest ally is Gonarthrus, which, however, differs in the venation 

 being that of a Dischistus with a broad cubital fork and an open anal 



cell. 



To Loew's description of the genus may be added : Occiput flat, not 

 inflated, briefly haired along the border. Ocelli disposed in an equi- 

 lateral triangle. Eyes of the male united for a long distance, with the 

 upper areolets enlarged and sharply separated from the smaller ones. 

 Antennae inserted at the centre between the eyes, approximate at the 

 base, with the third joint twice as long as the first. Face of the male 

 with long moustache. Thorax, scutellum and abdomen without distinct 



