33 HUMBLE CREATURES. 



Our little Ply, then, belongs to the highest of the 

 three subclasses of insects, inasmuch as it undergoes 

 a perfect transformation ; and, not to weary you with 

 any lengthened reference to orders and genera, we 

 will simply add, that on accoimt of its possessing 

 two wings, it is included in the Order Diptera, in 

 contradistinction to those tribes which are wingless 

 {Aptera), and other Orders characterized by the varied 

 nature of their organs of flight. 



Having thus cursorily surveyed this province of the 

 Animal Kingdom in order to ascertain what rank and 

 position are held by the Fly, let us now direct your 

 attention to the details of its structure ; and in in- 

 troducing this portion of the subject we will first 

 observe, that, simple and unassuming as its form may 

 appear to the superficial observer, it has been deemed 

 worthy of a large share of the zoologist^s notice ; for 

 its external members, as well as its internal organiza- 

 tion, have been almost as carefully scrutinized and 

 accurately described as those of man. 



If you examine the body of a Fly, you will find it 

 to. be composed of the three sections already referred 

 to : the head; the thorax or chest, joined to the head 

 by a thin neck ; and the abdomen. See Frontispiece 

 and Plate III. 



Let us examine each division seriatim. 



1. The head bears externally the organs of sense 

 and nutrition, that is to say, the antennae or feelers 

 the wonderful eyes (compound and simple), and the 

 proboscis ; within, it encloses the cerebral gangHon 



