STRUCTURE OF INSECTS. 331 



in the most perfect manner. When the legs are 

 very long, as in the Tipula* the body seems, 

 indeed, more to be suspended than supported by 

 them ; contrary to what obtains in quadrupeds, 

 where the feet are more immediately underneath 

 the points at which they are connected with the 

 trunk. 



The last joint of the tarsus is generally ter- 

 minated by a claw, which is sometimes single 

 and sometimes double, and which contributes to 

 fasten the foot, under a variety of circumstances, 

 both of action and of repose. With feet thus 

 armed the insect can ascend or descend the 

 perpendicular sides of a rough body with the 

 greatest ease ; but it is scarcely able to advance 

 a single step upon glass, or other polished sur- 

 faces, even when horizontal. The hooks at the 

 ends of the anterior pair of feet are directed 

 backwards, those of the middle pair inwards, 

 and of the posterior pair forwards ; thus afford- 

 ing the greatest possible security against dis- 

 placement. 



Many insects are provided with cushions at 

 the extremity of the feet, evidently for the pur- 

 pose of breaking the force of falls, and prevent- 

 ing the jar which the frame would otherwise 

 have to sustain. These cushions are formed of 



* It has been conjectured that the object in furnishing this 

 insect with legs of so great a length is that of enabling it to 

 walk among blades of grass. 



