MOTIONS OF INSECTS. 439 



different orders: but they seem in most to have joints answering to the hip 

 (coxa); trochanter; thigh {femur') ; shank {tibia) ; foot (tarsus) ; of perfect 

 insects, the legs of which they include. Cuvier, speaking of Coleoptera 

 and some Neuropte?-a, mentions only three joints. But many in these 

 orders (amongst which he included the Trichoptera) have the joints I have 

 enumerated. To name no more, the Lamellicornia, Dytisci, SdphcB, Sta- 

 p)hylini, Cicindcla:, and Gyrini, &c. amongst coleopterous larvse ; and the 

 Trichoptera, as well as the Libelhdina and Ephemerina, amongst Cuvier's 

 Kcuroptera, — have these joints, and in many the last terminates in a double 

 clavv.^ In some coleopterous genera the tarsus seems absent or obsolete. 

 The larva of the lady-bird {Coccinella) affords an example of the former 

 kind, and that of Chrysomela of the latter .'^ These joints are very visible 

 in the legs of caterpillars of Lepidoptera, and their tarsus is armed with a 

 single claw.^ The larvffi that have these legs walk with them sometimes 

 very swiftly. In stepping they set forward at the same time the anterior 

 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 kvf remarks upon spurious legs. Because their 

 muscles, instead of the horny substance that protects them in perfect legs, 

 are covered only by a soft membrane, they have been usually denominated 

 membranaceous legs ; since, however, they are temporary, vanishing alto- 

 gether 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 (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 extremities naked. Of these the upper one 

 is sharp, and the lower blnnt. 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 niotion, it is shut, and the claws are laid flat with 

 their points inwards ; but when it wishes to fix itself, the sole is opened, 

 becoming of greater diameter than before, and the claws stand erect with 



1 For examples of larvae having these joints, see De Geer, iv. 289. t. xiii. f. 20. 

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



2 Ibid. v. t. xi. f. 11. t. ix. f. 9. o. 



3 Lyonet, Tr. Anat. t. iii. f. 8. 



4 Mr. \V. S. WacLea}', where quoted above, objects to this term ; but as the 

 organs in question 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 

 distinction, to give them a different name from perfect legs, and at the same time 

 one that showed some aifinity to them. 



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