288 MOTIONS OF INSECTS. 



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 sta- 

 tion when it feeds or reposes, — I shall therefore call 

 them prolegs (propedes). These organs consist of 

 three or four folds, and are commonly terminated, 

 though not always, by a coronet or semicoronet of very 

 minute crooked claws or hooks. These claws, which 

 sometimes amount to nearly a hundred on one proleg, 

 are alternately longer and shorter. They are crooked 

 at both ends, and are attached to the proleg by the 

 back by means of a membrane, which covers about 

 two-thirds of their length, leaving their two extremi- 

 ties naked. Of these the upper one is sharp, and the 

 lower blunt. The sole, or part of the prolegs within 

 the claws, is capable of opening- and shutting. When 

 the animal walks, that they may not impede its mo- 

 tion, it is shut, and the claws are laid flat with their 

 points inwards ; but when it wishes to fix itself, the 

 sole is opened, beconung of greater diameter than be- 

 fore, and the claws stand erect with their points out- 

 wards. Thus they can lay stronger hold of the plane 

 of position^. 



The number of these prolegs varies in different spe- 

 cies and families. In the numerous tribes of saw-flies 

 (Tenthredo, L.), the larva? of which resemble those of 

 Lepidoptera, and are called by Reaumur spurious ca- 

 terpillars {fausses chenilles)^ one family (Ciinbex, F. 

 Lophyrus, Latr.) has sixteen prolegs ; a second {Hy- 

 lotoma, Latr. &c.) fourteen; another (l^enthredo, F.) 

 twelve ; and a fourth (Lyda, F.) none at all, having only 



" Lyonet,82— <, iii. /. 10-16. 



