286 MOTIONS OF INSECTS. 



this bubble, which is, as it were, its air-balloon. If it 

 moves upon the surface or horizontally, it bends its 

 body alternately to the right and left, contracting it- 

 self into the form of the letter S ; and then extending 

 itself again into a straight line, by these alternate move- 

 ments it makes its way slowly in the water ^. 



I have dwelt longer upon the apodous larvaB, or 

 those that are without what may be called proper legs, 

 analogous to those of perfect insects, because the ab- 

 sence of these ordinary instruments of motion is in 

 numbers of them supplied in a way so remarkable and 

 so worthy to be known ; and because in them the wis- 

 dom of the Creator is so conspicuously, or, I should 

 rather say, so strikingly, manifested — since it is doubt- 

 less equally conspicuous in the ordinary routine of na- 

 ture. But aberrations from her general laws, and 

 modes, and instruments of action, often of rare occur- 

 rence, impress us more forcibly than any thing that 

 falls under our daily observation. 



I come now to pedate larvae, or those that move by 

 means of proper or articulate legs. These legs (gene- 

 rally six in number, and attached to the underside of 

 the three first segments of the body) vary in larvae of 

 the different orders : but they seem in most to have 

 joints answering to the hip {coxa) ; trochanter ; thigh 

 {femur) ; shank (tibia) ; foot (larsus), of perfect in- 

 sects, the legs of which they include. Cuvier, speaking 

 of Coleoptcru and some Neuroptera^ mentions only three 

 joints. But many in these orders (amongst which he 

 included the Trichoptera) have the joints I have enu- 



* Swamm, BibLNat. Ed. Ilil!, ii. 44. b. 47, a. 



