A SECOND Edition of the " List of British Diptera " has become 

 imperative, not only because the First Edition is exhausted, 

 but because of the numerous additions, subtractions, and altera- 

 tions. About 300 species have been added to the old " List," 

 and about 500 names have been altered in some way or other, 

 such as being confirmed as British, placed under a different genus, 

 changed in synonymy, &c. Beyond that numerous other changes 

 have been suggested which have not been at present adopted, as 

 I have refused to make any change which might upon being tested 

 have to go back to the previous name. 



The "List" of 1888 was entirely my own composition, but as 

 a proof of the increased attention now given to British Diptera 

 I have to thank Messrs N. Rothschild, Theobald, Austen, Wain- 

 wright, Collin, and many others, for assistance in forming this 

 "List." 



A few words of explanation may be of use as to the value of 

 this " List " in certain families : 



Cecidomyidce ; no attempt has been made to cope with the vast increase 

 in genera and species which have been added to the European Fauna in the 

 last few years, because no British worker has attended to this family; the 

 alphabetical order of species and the old genera have been retained, and only 

 specially recorded species have been added. 



Mycetophilidce ; this family, though much improved, is still in a most 

 unfinished condition. 



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