2 DURHAM DIPTEKA. 



short life may be practically lengthened, if one is enabled 

 quickly to begin where a predecessor has left off. It is with 

 this object that these tables are given, in the hope that they 

 may enable others in the two counties to take up the study of 

 flies, and soon greatly to extend this very incomplete list. Of 

 course these tables are far from perfect, and in many cases 

 the identification of species is exceedingly difficult in certain 

 families of flies. They are intended in the first instance to 

 point out the characteristic differences in the species repre- 

 sented in this collection, but in order to make them available 

 for additions to our local list I have added in brackets the 

 names of a large number of British species which I have not 

 yet found in this county. They will also serve, I hope, by 

 showing the poverty of the collection, to arouse the desire on 

 the part of some to make it more worthy of the Society. They 

 are chiefly drawn from Schiner's excellent " Fauna Austriaca," 

 Vienna, 1862, with several modifications, and many omissions. 

 In the Syrphidae I have followed Mr. Verrall's splendid work 

 on the British Syrphidae, a large book of over 800 pages, 

 dealing at great length with every British species, and indis- 

 pensable to those who desire to study that family. Loew, 

 Macquart, Zetterstedt, Becker, Meade, and Stein have also 

 been consulted. I have to thank Mr. Austen, Col. Yerbury, 

 Mr. Henderson, Mr. Collin, Mr. Wainwright, Mr. Grimshaw, 

 and Herr P. Stein for their kind help from time to time. The 

 arrangement of the collection is that adopted by Mr. Verrall 

 in his last List of British Diptera, December, 1901. The 

 order is not rigidly adhered to in the tables owing to the 

 characters sometimes overlapping, but the number preceding 

 the name gives the proper position in that list. 



As I found it very difficult at first to form a mental picture 

 of some part merely from the descriptive word used, I have 

 added a few, somewhat rough, illustrations, which I hope may 

 make the meaning of terms a little clearer. They are mostly 

 tracings, sometimes slightly altered, taken from Walker's work, 

 which is now out of print. I have added a few of my own, 

 and also a Fly Chart, or Diagram, which, with its description 



