94 THE ANIMAL KINGDOM. 



these are supposed to assist the insect in its downward 

 flight, by fixing the atmospheric fluid, which glides over it 

 as they rise. 



The motion of a little Midge on the window-pane is 

 always zigzag, from right to left, and left to right. Some 

 wings have six or seven spots upon them, and are called 



WING OF GNAT. 



This wing differs in the various species of Gnats which 

 haunt our waterbutts, and tanks, and stagnant ponds. 

 Some have more beautiful scales than others, but this wing 

 of the common Gnat (Culex pipiens] is a good study 

 and a most pleasing object. Look at it with the lowest 

 power for the veining, and then with the highest for the 

 scales. 



The Gnats belong to that division of flies called Tipu- 

 lidse, and also Nemocera, which means having the head 

 branched. They all have long and beautiful antenna?, 

 which, in the males, are plumed and whorled like the stems 

 of Equisetum. 



The wings are narrow and lanceolate. 



Sub-costal vein ends a little before the tip of the wing. 



Radial, branched from the Sub-costal, and is forked. 



Cubital vein begins from the Prtebrachial small transverse. 



Mediastinal is between the Radial and Costal. 



Pmbrachial is also forked. There are fourteen areolets. 



The scales of a Gnat form test objects of the defining 

 power of an object glass. Scales are composed of two or 

 three layers of membrane, and probably the longitudinal 

 ridges in these scales may represent folds of the outer mem- 

 brane. We should not only see these stria?, but the delicate 

 transverse markings and projections of the lines beyond the 

 top of the scale. 



Gnats fly silently in winter and early spring, before the 

 thirst for blood is awakened, and then the female only sounds 

 the shrill clarion of war in her eager flight to and fro. See 

 the Gnat (Culex), mounted whole, and for the complete 



