278 MOTIONS OF INSECTS. 
v4) 
legs of the caterpillars of most Lepidoptera. Some, a 
kind of monopods, have only one of such prominences, 
which being always fixed almost under the head, may 
serve, in some degree, the purpose of an unguiform 
mandible. The grub of a kind of gnat (Tipula stercora- 
via, De Geer), and also another, probably of the Tipu- 
lidan tribe (found by De Geer in a subputrescent stalk 
of Angelica which he was unable to trace to the fly), 
have each a fleshy leg on the underside of the first seg- 
ment, which points towards the head and assists them 
in their motions*.—Others again go a little further, and 
are supported at their anterior extremity by a pair of 
spurious legs. An aquatic larva of a most singular form, 
and of the same tribe, figured by Reaumur, is thus cir- 
cumstanced. In this case the processes in question 
proceed from the head, and are armed with claws”. 
Would you think it—another Tipulidan grub is di- 
stinguished by ¢hree legs of this kind? It was first 
noticed by De Geer under the name of T7pula maculata 
(Tanypus, 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 a quarter of an 
inch in length. Its mode of swimming is like that of a 
serpent, 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, 
tentacula. ‘They resemble, by their length and rigidity, 
2 De Geer, vi. xo. f. 15,7, 7. evil. fa Sa pre 
>Reaum, vy. ¢. vi. f. 5, mm. 
