MOTIONS OF INSECTS. 269 



aud talons of such as dig ; and, to name no more, the ad- 

 mn-able faculty of such as cannot fly, to convey them- 

 selves with speed and safety, by the help of their webs, 

 or some other artifice, to make their bodies lighter than 

 the air ^." 



Since the motions, and instruments of motion, of in- 

 sects are usually very different in their preparatory states, 

 from what they are in the imago or perfect state, I shall 

 therefore consider them separately, and divide my sub- 

 ject into — motions of larvae, — motions of pupa?, — and 

 motions of perfect insects. 



I. Amongst larvce there are two classes of movers — 

 Apodoiis larvae, or those that move without legs, — and 

 Pedate larvae, or those that move by means of legs. I 

 must here observe, that by the term legs, which I use 

 strictly, I mean only jointed organs, that have free mo- 

 tion, and can walk or step alternately; not those spurious 

 legs without joints, that have no free motion, and cannot 

 walk or take alternate steps ; such as support the middle 

 and anus of the larva) of most Lepidoptera and saw-flies 

 {Sei-rijera). 



Apodous lai'vse seldom have occasion to take long jour- 

 neys ; and many of them, except when about to assume 

 the pupa, only want to change their place or posture, 

 and to follow their food in the substance, whether animal 

 or vegetable, to which, when included in the egg, the 

 parent insect committed them. Legs therefore would be 

 of no great use to them, and to these last a considerable 

 impediment. They are capable of three kinds of mo- 



' riii/sico-Theol. Ed. t3.36;i. 



