MOTIONS OF INSECTS. 439 
different orders: but they seem in most to have joints answering to the hip 
(cova); trochanter; thigh (femur) ; shank (dibia) ; foot (tarsus) ; of perfect 
insects, the legs of which they include. Cuvier, speaking of Coleoptera 
and some Neuroptera, mentions only three joints. But many in these 
orders (amongst which he included the Zrichoptera) have the joints I have 
enumerated. To name no more, the Lamellicornia, Dytisci, Silphe, Sta- 
phylini, Cicindela, and Gyrini, &c. amongst coleopterous larvae; and the 
Trichoptera, as well as the Libellulina and Ephemerina, amongst Cuvier’s 
Neuroptera,—have these joints, and in many the last terminates in a double 
claw.t 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 larve 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 larvee 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 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 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 motion, 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 larve having these joints, see De Geer, iv. 289. t. xiii. f. 20. 
t. xv. f. 14. ii, t. xii f 3. t. xvi. ff 5, 6. t. xix. f 4, &e. 
? Thid. v. t. xii f. 11. t. ix. f 9. 0. 
8 Lyonet, Zr. Anat. t. iii. f. 8. 
4 Mr, W. S. MacLeay, 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 affinity to them. 
FFR4 
