DURHAM DIPTERA. 1 5 



(C.II.) very puzzling at first. In order to shorten the 



Tables, I have ventured to introduce a system of 



numbering and lettering for the veins and cells of 



the wing, which is merely an extension of the plan 



adopted by Schiner and others. It may often be 



artificial, but it is distinctly useful, and I consider it 



to be a very great improvement on the long clumsy 



names used by English authors. That there is great 



confusion in wing terminology among various writers 



will appear from the tables of vein and cell names 



at the end of F. It is greatly to be desired that some 



uniformity could be arrived at. I do not suppose 



that a suggestion from a mere outsider would be 



likely to do anything to forward that result, but the 



following system is simple and short, and the use of 



figures and letters, instead of words, makes it of easy 



international application. 



As an instance of how it is calculated to shorten 

 descriptions, I give the translation of Schiner's first 

 character for dividing the genus Bibio into two parts, 

 using English vein-names. 



" The basal portion of the cubital vein, where it 

 springs from the sub-costal vein near the middle of 

 the wing, measured from its source to the middle 

 cross vein, much, or at least, distinctly longer than 

 the middle cross vein which forms an angle with it." 

 In the following pages the same description reads 

 thus : 



" V.3 1 . much, or at least, distinctly longer than X.4." 

 The system here adopted is as follows : 

 A number preceded by Vindicates a longitudinal vein. 

 A number preceded by X. indicates a cross vein. 

 A number preceded by O. indicates a cell. 

 A number followed by a. indicates an upper branch 

 of a long vein. 



A number followed by b. indicates a lower branch 

 of a long vein. 



