178 [August, 



the females of opncn, oiigricornis, and luf/ubris* The great value of 

 Becker's work can be realised by only those who previously studied 

 the family, but he was weak in his knowledge of the females of this 

 group, and was led to include females with dark halteres under his 

 opaca, and to the conclusion that the colour of the halteres was vari- 

 able in that species. If his knowledge of the sex had been greater 

 he would have recognised that the type specimen of opaca in the 

 Paris Museum was not the same as the species he described under 

 that name. 



I have recently critically examined the type specimens of opaca 

 and perennis, and find that the species standing in our List as opaca, 

 and described by I^ecker under that name, is identical with pet^ennis, 

 Mg., while Meigen's opaca is a different species described by him in 

 his Syst. Beschr, vi, p. 216, as follows : — 



" 12. Pn. OPACA, 

 " Schwarz ; Scliwinger und Beine braun ; Knie gelb ; Fliigel muchfarbig. 

 " Nigra ; halteribus pedibusque fuscis ; genubus luteis : alis infumatis. 



" Matt grauschwarz, mit braunen Schwingern. TJntergesicht glanzend 

 " schwarz, mit einer vertieften Langslinie. Taster und Fuhler schwarz. Beine 

 *' schlank, dunkelbraun, mit gelben Knien. Fliigel ruszfarbig, arn Vorderrande 

 " zart gewimpert ; Kandadern dunkelbraun ; die vierte Liingsader fehlt. — Nur das 

 " Weibchen.— li Linie." 



The type specimen has a broad, shining proboscis which Meigen 

 probably mistook for the face, his description of the face as shining 

 black can hardly be explained in any other way, as the face of a 

 I'hora is short and almost entirely hidden by the antennae. The 

 specimen agrees with the description in other respects, and I un-- 

 hesitatingly consider it a female of nigricornis, Egger, which, 

 together with trinervis, Beck., possesses a long broad proboscis. 



To turn to oth.T descriptions of opaca we find that Macquart's 

 appears to be only an abbreviation of Meigen's. Zetterstedt made 

 no mention of the shining face, but retained " halteres nigricantes," 

 thereby shutting out perennis, his description of the wings as having 

 a streak along the costa from the thick veins to near the wing tip 

 applies best to luguhris ? , but the description might cover several 

 species. 



Schiner's opaca cannot possibly be that of Becker, for he called 

 the palpi narrow, yet fairly long, the proboscis more projecting than 



* I leave the publication of characters whereby these species may be known to Dr. J. H. 

 Wood, who is at work upon a revision of the genus. 



