'I'uhaiius boviitiis. The common gad-fly. 



CHAPTER 111. 



OF THE CLASSIFICATION OF DIPTERA. 



In the second class, Diptera, the metamorphosis, as in 

 Lepidoptera, is amorphous. Larva with minute corneous 

 mandibles, moving horizontally ; without articulate or pre- 

 hensile feet ; feeds on recent or decaying animal and vege- 

 table substances. Imago of Diptera with the parts of the 

 mouth variously developed ; the mandibles never possessing 

 the horizontal motion, or masticatory power; the fore wings 

 fully developed ; the hind wings undeveloped; assuming the 

 appearance of small pedunculated knobs, and denominated 

 halleres or poisers; tarsi five-jointed. 



