378 STRUCTURE OF INSECTS. 



pair of wings, because they have been found wanting 

 in some two-winged insects, and present in some four- 

 winged ones, as in the dytiscus marginalia. 



The legs of insects consist of nearly the same distinct 

 parts as those of larger animals. They are : 



1. The hip, (coxa?) which is immediately articulated 

 to the side of the sternum. 



2. The thigh, (femur,*) which is articulated to the 

 hip. 



3. The leg, (tibia,) which is articulated to the thigh. 



4. The foot or toe, (tarsus,) which consists of several 

 joints, the first of them articulated to the leg, and the 

 last to 



5. The claw, (unguisj) which terminates the organ. 



The form and articulations of these are often exceed- 

 ingly curious ; but we find in them all that perfect har- 

 mony of organization and use, which can be so clearly 

 traced in all the mechanism of animated nature, and 

 which indeed forces itself upon our notice, whether we 

 attempt to trace it or not. Thus, if the insect has only 

 to walk and not to leap, the thighs are slender; but 

 when it has to leap, they are swelled out in breadth to 

 afford room for the action of the muscles ; and the 

 swelling always takes place in that direction which is 

 best calculated for giving ease and force to the motion. 

 The articulation of the femur is equally well adapted 

 to the habits of the insect. In some, the motion is 

 most easy forwards, in others backwards, and in a con- 

 siderable number it answers equally both ways. 



The tibia, too, is made to answer all the purposes of 

 a simple leg; or it is lengthened, flattened, and fringed, 

 that it may serve as an oar ; or yet again it is made 



