THE ENTOMOLOGIST. 



101 



Fig. 11. — Sciara. 



The inspection of the wiug of a fly is generally sufficient 

 to ascertain the genus of the individual to which it was 

 attached, and there is much interest in tracing the great 

 variation of the wing-bones of Diptera, and in observing how 

 many changes are effected by the modifications of a fevv 

 parts of the structure. Strength and swiftness of flight is 

 generally accompanied by many wing-bones, but in numerous 

 cases the bones are many, and the flight is very feeble. In a 

 few groups some of the bones are very slender, so as to be 

 termed secondary. This is more conspicuous in some 

 Hymenoptera, such as Chalcidias, when the fore wing has 

 generally only one bone near the costa, but in the largest 

 species one or two diff'use veins or incipient bones in the 

 disk may be indistinctly traced. The return of mild or warm 

 weather and the morning sun impart much vivacity to the 

 wings by means of electric currents through the bones, and 

 recal the Diptera from a torpid state, like as comets become 

 developed and move more rapidly when they approach 

 the sun. 



Five of these six figures, and the preceding six in the 

 'Entomologist,' pp. 36, 37, represent the wing-bones of 

 MycetophilidaG : this family forms two divisions, Myceto- 

 philini and Sciarini, of which the first includes seven 

 sub-families, — Diadocidina;, Mycetobina^, Boletophilina^, 



