8 G. E. J. NIXON 



which is certainly artificial though based on a striking character while the other 

 seems to be transitional towards the polyphyletic Microgaster s.l. 



Snellenius Westwood, for all its bizarre appearance, represents only an extreme 

 development of Microplitis. 



I have made no attempt to subdivide Microplitis into species-groups though this 

 will need to be done eventually. 



MIR AX Haliday 



The position of this genus is doubtful but there is some justification, I think, for the 

 suggestion put forward by my colleague, Dr. J. F. Perkins, that it could be regarded 

 as the basic member of an independent tribe within the Microgasterinae, of world- 

 wide distribution and containing a few closely related genera. 



The British Museum contains Mir ax from all parts of the world, especially S. Africa 

 and Brazil. I have examined these specimens and recognised several distinct species 

 among them. 



The species of Mirax show a remarkable uniformity in wing venation ; indeed, 

 there is little departure from the pattern shown in Text-fig. 4. Variation occurs in 

 the degree to which the stigma may be prolonged distally. When the distal narrow- 

 ing is pronounced, the tip of the stigma tends to be more weakly pigmented than 

 elsewhere. A differentiated metacarp is never present. 



In common with the Microgasterini, Mirax has the spiracles of the first tergite 

 situated on the lateral, membranous part of the segment, remote from the more 

 heavily sclerotised, median plate. 



AD ELI US Haliday = AC O ELI US auctt. 



This genus has no obvious relationship with Mirax nor, in my opinion, has it any 

 clear affinity with the Microgasterini, even at tribal level. Perkins has suggested 

 that Adelius may be related to the Cheloninae, a view to which I give my support. 

 Against it, of course, is the striking difference between the gaster of Adelius and that 

 of the typical Cheloninae. The type-species, subfasciatus Haliday, is remarkable in 

 having the gaster smooth, polished and with no obvious suture between tergites 1 

 and (2 + 3). But there exist in the British Museum a few apparently undescribed 

 S. African species, about whose affinity with Adelius there can be no question at all 

 but in which tergites 1 and (2 + 3) have become entirely rugose and separated by a 

 well marked suture. I regard these species as belonging to de Saeger's Paradelius. 

 In another unnamed S. African species, tergite (2 + 3) has become even more 

 sculptured and lengthened and divided into its two component parts by a second 

 rugose suture. The gaster in this species presents a strongly sclerotised carapace 

 with two rugose sutures and concealing all the segments posterior to tergite (2 + 3) . 

 The gaster thus comes to have a deceptive resemblance to that commonly found in 

 some of the genera of the Triaspidini (now in Blacinae, Muesebeck and Walkley, 

 1951). 



