INSECTS. 



233 



Fly (fig. 18) is well developed in this particular, enabling it 

 to walk with perfect ease even on glass or the smoothest 



FIG. 17. ANTEXITA OF COCK-CHAFFER (Melolontha vulgaris). 



surface, and in any position. Insects do not breathe by 



FIG. 18. FOOT OF FLY, MAGNIFIED. 



lungs or gills, but by means of branched tubes called 

 "tracheae," which convey the air to the interior of the 



