MOTIONS OF INSECTS. 279 



out. The insect moves them both together, as a lame 

 man does his crutches, either backwards or forwards. 

 The two posterior legs are placed at the anal end of 

 the body. They are similar to the one just described, 

 but larger, and entirely separate from each other, being 

 not, like them, retractile within the body, but always 

 stiff and extended. These also are armed with hooks. 

 In walking, this larva uses these two legs much as the 

 caterpillars of the moths, called Gcomeirce, do theirs. 

 By the inflexion of the anus it can give them any kind 

 of lateral movement, except that it can neither bend 

 nor shorten them, since like a wooden leg, as I have 

 before observed, they always remain stiff and extend- 

 ed^. Lyonet had observed this larva, or a species 

 nearly related to it ; but he speaks of it as having four 

 legs, two before and two behind. Probably, when he 

 examined them, the common base, from which the feet 

 are branches, was retracted within the body**. 



Generally speaking, however, in these apodous walk- 

 ers the place of legs is supplied by fleshy and often re- 

 tractile mamillas or tubercles. By means of these and 

 a slimy secretion, unaided by mandibular hooks, the ca- 

 terpillar of a little moth (Ilepiulus Testudo, F. Apoda^ 

 Haworth) moves from place to place *^i — A subcuta- 

 neous larva belonging to the same order, that mines 

 the leaves of the rose, moves also by tubercular legs 

 assisted by slime. It has eighteen homogeneous legs, 

 with which, when removed from its house of conceal- 

 ment, it will walk well upon any surface, whether ho- 



^ De Geer, vi. 395— . Plate XXIII. Fio. 7. Forcles:, «. Iliiid- 

 legs, bb. " Lesser £. i. 96. note f. 



' Klemann, Bt27r«^c5 324. 



