470 'XIPULIDJi. 



Of course, a different interpretation might be offered, name!}', . 

 to consider the 2nd vein as being forked and (he 3rd vein present, 

 what I recognise as the anterior cross-vein being considered its 

 basal section : in this case the 2nd vein would end at the tip of 

 the wing, the anterior cross-vein being obliterated, and the Srd' 

 vein forming tlie whole upperside of the discal cell. But this 

 interpretation would only cause more confusion in the identifi- 

 cation of the ramifications of the 4th vein. 



A close study of the venation of Gonomyia, especially of the 

 4th longitudinal vein with its branches, convinces me that the 

 delineation of the veins as admitted in this work is correct. This 

 is proved by sucli species as C. j^'t'oaima and aperta, in A^hich the 

 2nd longitudinal vein is forked, whilst the 3rd vein and the 

 anterior cross-vein are both present. In support of this may be 

 quoted Osten Sacken's remarks in his elaborate ' Monograph on 

 the North-American Tivulidte ' : " Avhenever the discal cell is 

 open, it coalesces with the 3rd posterior cell, and thus it becomes 

 apparent that it is the anterior branch of the 4th longitudinal 

 vein which is forked"'; to which he adds a footnote, " Exce])tions 

 are merely individual: tlius I have seen a spcicimen of (r. suh- 

 cinerea, the discal cell of which was coalescent with the 2nd 

 posterior cell." 



Individual variation in tliis genus, it may be remarked, is 

 rather common. Moreover, Osten Sacken (t. c. p. 178), noted 

 that tlie anterior branch of the 2nd vein was occasionally very 

 faint, and whilst his work was in the press, he discOA^ered a new 

 species, G. mcmca, in which the 2nd longitudinal vein was simple,* 

 and he suggested that a new genus might reasonably be created 

 for it. Nevertheless, I refrain from doing so at present, as it is 

 evident that the genus Gonomyia iorms a tolerably well circum- 

 scribed group of species, which it would be undesirable to dis- 

 member for each modification of venation. 



Table of Species. 



1. The 2nd longitudinal vein nut forked ; 



discal cell present 2. 



The 2nd longitudinal vein shortly but 

 distinctly forked; discal cell present 

 or absent 3. 



2. Posterior cross-vein at base of discal 



cell ; 1 st posterior cell much narrowed 



at tip; margin of thoracic dorsum 



* concolorous iiicojnpleta, sp. n,, p. 471 . 



Posterior cross-vein distinctly before 



base of discal cell ; 1st posterior cell 



barely narrowed at tip ; margin of 



thoracic dorsum yellowish Jtavomarfiinata, sp. n., p. 



Exactly as in my two new species G. Inconqjleta &i\A flavomarginata. 



