INSECTS. 



167 



the bottom, where they are speedily hatched. The larva 

 is a somewhat uncouth, broad, and flat, olive- coloured 

 animal, rather spider-like, having six sprawling legs, which 

 crawls about the mud at the bottom of ponds, or glides 

 by a singular mechanism through their waters. The 

 hinder extremity of the body is furnished with several 

 leaf-like processes, capable of being brought closer toge- 

 ther, or opened at pleasure. These close the orifice of a 

 cavity, whose sides are very muscular. When the Insect 

 wishes to move rapidly, it opens this cavity, which thus 

 becomes filled with water ; then, by a contraction of the 

 walls of the cavity, the water is forcibly ejected in a stream 

 as from a syringe ; and, by the re-action produced by the 

 impact of the jet cFeau upon the surrounding fluid, the 

 creature shoots ahead, with its legs closely packed along 

 its sides. 



But the most singular part of its structure is its face. 

 " Conceive," says the graphic and eloquent Kirby, " your 

 under lip to be bony instead of fleshy, and to be elongated 

 downwards, so as to wrap over your chin, and extend to 

 its bottom j that this elongation is then expanded into a 

 triangular convex plate, attached to it by a joint, so as to 

 bend upwards again, and fold over the face as high as the 

 nose, concealing, not only the chin and the first-mentioned 

 elongation, but also the mouth and part of the cheeks : 

 conceive, moreover, that to the end of the last-mentioned 

 plate are fixed two other convex ones, so broad as to cover the 

 whole nose and temples ; that these can open at pleasure 

 transversely like a pair of jaws, so as to expose the nose and 

 mouth, and that their inner edges, where they meet, are 



