MOTIONS OF INSECTS. 



225 



the Tipularian 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 segment, 

 which points towards the head and assists them in their 

 motions. 1 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 circumstanced. In this case the 

 processes in question proceed from the head, and are armed 

 with claws. 2 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 a quarter of an inch in length. Its 

 mode of swimming is like that of a serpent, with an undu- 

 lating 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, wooden legs. The anterior leg is 

 attached to the underside, but towards the head, of the first 

 segment of the body. It is long and cylindrical, placed per- 

 pendicularly or obliquely, according to the different move- 

 ments 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, 



1 De Geer, vi. t. xxii. f. 15. i. t. xviii. f. 8. p. 



2 Reaum. v. t. vi. f. 5. m m . 



VOL. II. Q 



