106 [April, 



THE GENUS HETEROMYZA, Fallen {HELOMYZID.E). 

 BY J. E. COLLIN, F.E.S. 



Among some insects recently sent to me by Mr. J. W. Terbury 

 was a specimen taken by Mr. Grimshaw, of the Edinburjjb Museum, 

 at Spring AVood, Bradford, Yorkshire, on August 5th 1893, and 

 labelled by him TheJida ocidata, Fin. ; this upon examination proved 

 to be the true Heteromyza (Thelida) oculata of Fallen and Zetter- 

 stedt, and induced me to study the other species of the genus. The 

 result of my investigations will be found in the following pages. 



The genus Heteromyza was established by Fallen in 1820, for the 

 reception of two species, R. oculata and H. buccata ; Meigen, Mac- 

 quart, Zetterstedt, and Desvoidy, all added to the number of species, 

 Desvoidy re-describing the genus under the name Thelida, but it was 

 very far from being a natural genus until Loew, in 1859, dealt with 

 it in his paper on the European Helomyzidce ; he retained Fallen's 

 S. oculata as the type, because it was, from the family and generic 

 descriptions, evidently the species Fallen had in his mind when he 

 established the genus ; the other described species that Loew con- 

 sidered congeneric with H. oculata were H. atricornis of Meigen, 

 H. cinerella of Macquart, and H. scntellata of Macquart, but he 

 considered Macquart's two species as only varieties ; he had not 

 noticed the fact of Antliomijza rotundicurnis, Zetterstedt, belonging 

 to the genus, and did not refer to Desvoidy's genus and species at all. 

 Schiner and Eondani, of subsequent writers, were both apparently 

 ignorant of Loew's work, and used Desvoidy's name TlicUda for the 

 present genus, while they retained the name Heteromyza for the 

 species upon which Loew had established the genus Tephrochlamys. 

 Macquart was the first to point out that Thelida of Desvoidy was a 

 synonym of Heteromyza, Fin., and it is an absolute synonym of 

 Heteromyza as at ])resent restricted. 



The only addition I make to Loew's definition of the genus is to 

 bring in characters that will include his Tephrochlamys maynicornis 

 (the female of H. oculata, Fin.) ; Loew himself considered it possible 

 that his T. marpiicornis might prove to be only the female of H. ocu- 

 lata, a species which he knew only from descriptions. The genus, as 

 I recognise it, may be known by the following characters, those given 

 in italics being sufficient to separate it from all the other genera of 

 the Helomyzidce. 



