36 DURHAM DIPTERA. 



I. 



ANALYTICAL TABLES OF GENERA AND SPECIES 

 WITH LISTS OF LOCAL SPECIES. 



Order.— DIPTERA. 



Insects with one pair of wings, and one pair of halteres in 

 place of hind wings, 5-jointed tarsi, and mouth adapted for 

 sucking, proboscis not spirally coiled. 



Sub-Order I.— ORTHORRHAPHA. 



Flies with mummy-pupae. 



Section I.— NEMATOCERA. 



Family L— PULICIDiE (The Fleas). 



Verrall lists thirty British species of Fleas. I know nothing 

 about them. 



Family II.— CECIDOMYID^E (The Gall Gnats). 



I have not attempted these difficult little flies, whose study 

 involves minute microscopical work. They have not been 

 worked in Britain to any extent, and await the advent of 

 some young, clear-sighted, patient entomologist. The larvae 

 live mostly in galls and other plant malformations. The flies 

 are very hard to identify in the dry state. 



Family III.— MYCETOPHILID^E (The Fungus Gnats). 

 The larvae live mostly in fungi and other vegetable matter. 



I have scarcely touched this family, and can only give a 

 short list of the few species I have been able to identify. But 

 I subjoin a table of the most of the British genera, taken from 

 Schiner. 



Note. — It must be borne in mind that in the wings of 

 many Mycetophilidae, and in other families also, according to 

 Schiner's system, which is here followed, the base of V.3. is 

 short and thick, looking like a X-vein, and that X.4. often 

 looks like the base of V.3., and is in a line with it: see Plate 

 IV. 4, where X is X.4., and the short X-vein beyond is con- 

 sidered as V.3 1 . 



