﻿On the Bomhyliid Faviia of Souih Africa (DIptem). 73 



SUIÎFAMILY USIINAE. 



COESOMYZA, Wiedeiuann (1820). 



Of this peculiar genus, very cliaracteristic of the South African 

 Fauna, there are in the collection numerous specimens, representing 

 all the known species, with the addition of some new ones. The 

 special feature of the genus resides in the facial circular brush, which 

 consists of a dense pubescence of short hairs clothing the anterior part 

 of the frons and the whole face, which is surrounded by more rigid 

 and often differently coloured hairs. From this dense brush are 

 projecting on the upper side the antennae (the basal joints of which 

 are often clothed by a tuft of hairs of different colour), and below the 

 proboscis and the long palpi. A similar conformation of the face is 

 to be found only in the North American genus Pantarbes, Osten 

 Sacken, which, however, has a closed first posterior cell, and in the 

 Australian genus Laslojrrosopa, Macquart. But this last genus, as 

 already stated by Schiner in the Novara work, is synonymous with 

 CorsoDiyza, its type species, Lasioiirosoim higotii, being Corsoniyza 

 nigripes, as confirmed )iy a specimen in the collection labelled under 

 this name by Bigot. 



The species in the collection are much alike in habitus and in the 

 colouring of the body fur ; they probably mimic Hymenoptera, having 

 a very great resemblance to certain species of Osmia. They can be 

 distinguished as follows : 



1 (M). Third aiitemial joint wholly black ; anal cell closed and iisually pro- 



vided with a short stalk. 



2 (3). First antennal joint elongate, as long as the half of the third, which 



is broad ; base of the antennae pale-haired ; face yellow, Avith the 

 circular brush not iiiarginated with black ; tiV)iae and tarsi red. 



simplex, Wied. 



3 (2) First antennal joint short, always shorter than the half of the third. 



•t (5) Hind tibiae densely feathered with vei-y long black hairs ; face yellow, 

 the circular brush not niarginated with black hairs ; antennae 

 with the first joint pale-haired and the third joint broad. 



2>cnnipcft, Wied. 



5 (4) Hind tibiae not densely feathered, sometimes only thinly ciliated. 



6 (13) Facial brush formed by whitish or pale yellowish hairs. 



7 (8) First antennal joint clothed on the upper side with black hairs, which 



form a striking black tuft within the 1 :)rush ; this last is surrounded 

 with dense black hairs. Tibiae and tarsi black ; third antennal joint 

 narrow, but a little dilated at end . . ni'jrii>cs,Wied. 



8 (7). First antennal joint with yellowish or whitish hairs; third antennal 



joint filiform and much dilated at end. 



