284; MOTIONS OF INSECTS. 



claw^. In some coleopterous genera the tarsus seems 

 absent or obsolete. The larva of the lady-bird {Cocci- 

 nella) affords an example of the former kind, and that 

 of Chrijsomcla of the latter''. These joints are very 

 visible in the legs of caterpillars oi Lepidoptera, and their 

 tarsus is armed with a single claw ". The larva? that 

 have these legs walk -with them sometimes very swiftly. 

 In stepping they set forward at the same time the ante- 

 rior and posterior legs of one side, and the intermediate 

 one of the other ; and so alternately on each side. 



Pedate larvae are of two descriptions : those that to 

 perfect legs add spurious ones with or without claws, 

 and those that have only perfect legs. I begin with the 

 former — those that have both kinds of legs. But first 

 I must make a few remarks upon spurious legs. Because 

 their muscles, instead of the horny substance that pro- 

 tects them in perfect legs, are covered only by a soft mem- 

 brane, they have been usually denominated membrana- 

 ceous legs : since, how ever, they are temporary, vanish- 

 ing altogether when the insect arrives at its perfect state, 

 — are merely used, for they do not otherwise assist in 

 this motion, as props to hinder its long body, when it 

 walks, from trailing on the ground ; to push against the 

 plane of position; and, by means of their hooks or claws, 

 to fix itself firmly to its station when it feeds or reposes, 

 — I shall therefore call them prolegs (jpropcdes'^). These 



" For examples of larvae having these joints, see De Geer, iv. 289. 

 /. xiii./. 20. t. XV. f. 14. ii. /. xii. /. 3. /. xvi./. 5, 6. /. xix./. 4, &c. 



" Ibid, v, t. xi./. 1 1. <. ix./. 9. o. ' Lyonet, Tr. Anat. t. m.f. 8. 



'' Mr. W- S. IMacLea}', where quoted above, objects to this term ; 

 but as the organs in ([ucstion are generally given to the animal to 

 assist in its motions, and have been universally regarded as a kind 

 of legs, it was judged best for the sake of distiuciion to give them a 



