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Order VI. 

 DIPTERJ. 



X HE insects of this Order, as the name im- 

 plies, have two wings only. These are thin, 

 membranous, transparent, and nervous. On 

 the wings of the gnat we may perceive, by the 

 aid of a magnifier, some little scales similar to 

 those on the wings of butterflies and moths, 

 but much smaller, and disposed in the direction 

 of the nerves only. In the Order Diptera the 

 wings are generally placed horizontally on the 

 body of the insect, one covering the other, in- 

 somuch that they cross and hide the abdomen. 

 In some genera, however, they are differently 

 situated, and leave the body quite exposed. 

 There is one very striking particular observable 

 H 3 



