INSECTS. 



succeeds the thigh (femur), which is the thickest and most robust 

 of all the divisions of the limb. The next piece, called the shank 

 (tibia), is occasionally of considerable length, and is connected 

 with the last by a hinge. To its extremity is appended the foot 



FIG. 63. KIND LEG OF BEE. 



(tarsus), composed of a consecutive series of small segments, vary- 

 ing in number from five to one, the last of which is armed with 

 claws, or other appendages, adapted to different kinds of pro- 

 gression. With these divisions of the leg it is necessary that the 

 student should be thoroughly acquainted, as we shall again and 



again have to refer to them hereafter. 



FIG. 69. WING OF DRAGON-FLY. 



The wings of insects, when present, are invariably attached to 

 the two posterior segments of the thorax, Avhich are strengthened 

 in every possible manner, so as to afford a support of sufficient 

 density and firmness to sustain the violent exertions of the 

 muscles employed in flight. Few things are met with in Nature 

 more admirable than these structures. They present, indeed, a 

 combination of strength and lightness absolutely beyond any- 

 thing of human invention, and as instruments of flight they much 

 surpass the wings of birds, both in the power and precision of 

 their movements. 



In the dragon-flies, by far the most powerful fliers in the insect 

 world, all four wings are of equal size, and consist of a thin mem- 



