MOTIONS OF INSECTS. 279 



in two, against the sides of ditches or the stalks of aqna- 

 tic plants. If it is placed in a glass half full of water, it 

 so fixes itself against the sides of it, that its head and 

 tail are in the water while the remainder of the body is 

 out of it ; thus assuming the form of a siphon, the tail 

 end being the longest. When this animal is disposed 

 to feed, it lifts its head and places it horizontally on the 

 surface of the water, so that it forms a right angle with 

 the rest of the body, which always remains in a situation 

 perpendicular to the surface. It then agitates, with vi- 

 vacity, a couple of brushes, formed of hairs and fixed in 

 the anterior part of the head, which producing a current 

 towards the mouth, it makes its meal of the various spe- 

 cies of animalcula, abounding in stagnant waters, that 

 come within the vortex thus produced. As these ani- 

 mals require to be firmly fixed to the substance on which 

 they take their station, and their back is the only part, 

 when they are doubled as just described, that can apply 

 to it, — they are furnished with minute legs armed with 

 black claws, by which they are enabled to adhere to it. 

 They have ten of these legs : the four anterior ones, 

 which point towards the head and are distant from each 

 other, are placed upon the fourth and fifth dorsal seg- 

 ments of the body ; and the six posterior ones, which 

 point to the anus and are so near to each other as at first 

 to look like one leg, are placed on the eighth, ninth, and 

 tenth. When the animal moves, the body continues 

 bent, and the sixth segment, which is without feet and 

 forms the summit of the curve, goes first ^. De Geer 

 named the fly it ))roduces Tijmla amphibia : it seems 

 not clear, from his figure, to which of the modern ge- 

 " Dc Geer, vi. 380—/. xxiv./. l-D. 



