MOTIONS OF INSECTS. 435 
tribe, figured by Reaumur, is thus circumstanced. In this case the pro- 
cesses in question proceed from the head, and are armed with claws.* 
Would you think it — another Tipularian grub is distinguished by three 
legs of this kind? It was first noticed by De Geer under the name of 
Tipula maculata (Tanypus monilis Meig.), who gives the following account 
of its motions and their organs: — It is found, he observes, in the water of 
swampy places and in ditches, is not bigger than a horse-hair, and about 4 
quarter of an inch in length. Its mode of swimming is like that of a ser- 
pent, with an undulating motion of the body, and it sometimes walks at the 
bottom of the water, and upon aquatic plants. The most remarkable part 
of it are its legs, called by Latreille, but it should seem improperly, tenta- 
cula. They resemble, by their length and rigidity, wooden legs. The an- 
terior leg is attached to the under side, but towards the head, of the first 
segment of the body. It is long and cylindrical, placed perpendicularly or 
obliquely, according to the different movements the animal gives it, and 
terminates in two feet, armed at their extremity by a coronet of long 
moveable hooks. ‘These feet, like the tentacula of snails, are retractile 
within the leg, and even within the body, so that only a little stump, as it 
were, remains without. 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 Geometre do theirs. By the 
inflection 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 extended.* 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them, the common base, from which the feet are branches, was retracted 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 walkers the place of legs 
is supplied by fleshy and often retractile mamillx or tubercles. By means 
of these and a slimy secretion, unaided by mandibular hooks, the caterpillar 
of a little moth (Apoda Testudo) moves from place to place4 A subcu- 
taneous 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 horizontal, inclined, or 
even vertical. But the greatest number of legs of this kind that distin- 
guish any known larva is to be observed in that of a two-winged fly 
(Scena Pyrastri) that devours the Aphides of the rose. This animal has 
six rows of tubercular feet, with which it moves, each row consisting of 
Seven, making in all forty-two. The grub of the weevil of the dock 
1 Reaum. v. t. vi. f. 5. mm, ; 
2 De Geer, vi. 895. Mr. W.S. MacLeay is of opinion that these legs are pedun- 
culated spiracles (Philos. Mag. N. Series, No. 9, 178.) ; but it is evident from De 
eer’s account that the animal uses them as legs, and like legs they are armed 
With hooks or claws. 
5 Lesser, 1. i. 96. note f. 4 Klemann, Bettriige, 824. 
5 De Geer, i. 447. t. xxxi. fi 17. ® Ibid. vi. 111, 
Fr2 
