544 THEREVID.E 



14 (13) Basal antennal joint not swollen nor more bristly than usual, 

 shorter than the other two joints together (fig. 317). Frons 

 bare. Abdomen elongate, oblong rather than conical. 

 Almost bare species. 



3. PSILOCEPHALA. 



Fig. 317. — Psilocrphala ardca S- x 33. 



Synonymy. — I believe that Cionophora Egger is an absolute synonym of 

 Xestmyiyza, and I very much doubt the distinctness of Baryjihora Loew, I'abiida 

 Walker, or Pachyrrhiza Philippi ; it is noteworthy that Loew made no reference 

 to Xestomyza when founding his genus Baryphora, and his figure of the antennas 

 is very misleading ; Egger also made no reference to either Xestomyza or Baryphora 

 when founding Cionoj^hora ; I possess several specimens of Xestomyza chrysanthemi 

 and one female of Baryphora speciosa, and have endeavoured to show their 

 differences. Tahuda Walker (1856) and Pachyrrhiza Philippi (1865) are probably 

 synonyms of Xestomyza Wied. (1820) or Baryjihora Loew (1844), but the American 

 entomologists profess to distinguish Tahuda by its less produced and less flattened 

 frons and its more pubescent basal antennal joint. Macquart's genus Eocajyata 

 was in my opinion founded on an injured or deformed specimen of an ordinary 

 Thereva^ and I believe (though I am not quite certain) that I possess the original 

 specimen of Ex. anthracoides, and if so it is very closely allied to T. fulva but may 

 be distinct as there are indications of cloudings on the cross-veins and on the upper 

 margin of the discal cell after the discal cross-vein ( = T. arcuata ?). I have given a 

 more limited interpretation of the genus Dialineura than has usually been done 

 as I have placed the most stress upon Rondani's second character, " Antennae 

 " articulo primo incrassato," and have ignored his character founded on the open 

 fourth posterior cell. The genus Phycus Walker may have been misunderstood by 

 subsequent authors, but my characters have been drawn from P. canescens only. 

 Aiudjarrhynchus Macquart is very closely allied to Dialineura and Psilocejthala 

 but has the eyes of the male well separated. Some of the other genera have been 

 very imperfectly distinguished and when well known may be refounded on better 

 characters or be suppressed. 



1. THERBVA. 



Thereva Latreille,, Precis car, gen. Ins., 167 (1796). 



Medium-sized flies of rather conical shape, clothed with 

 dense furry pubescence which obscures the dark ground colour, 

 and may be silvery white, fulvous, brown, or even mainly 

 black in colour. 



Head (fig. 315) semicircular but not flat behind, short, and without any obvious 

 neck to connect it with the thorax, but not crammed on to the thorax. Frons 



