INSECTA. 291 



the mouth of these aquatic larvae, for the oral apparatus here forms 

 an instrument of prehension adapted to seize prey at a distance, 

 and constitutes, in fact, a kind of projectile forceps of a very 

 curious construction. Let the reader contrast the following de- 

 scription with that already given of the oral organs of the dragon- 

 fly ( 295), and observe the remarkable difference : a Conceive," 

 say Kirby and Spence,* " your under lip to be horny instead of 

 fleshy, and to be elongated perpendicularly downwards, so as to 

 wrap over your chin and extend to its bottom ; that this elonga- 

 tion 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-men- 

 tioned elongation, but the mouth and part of the cheeks : conceive, 

 moreover, that to the end of this 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 cut into numerous sharp teeth or spines, or 

 armed with one or more long and sharp claws : you will then 

 have as accurate an idea as my powers of description can give of 

 the strange conformation of the lip in the larvae in question, which 

 conceals the mouth and face precisely as I have supposed a similar 

 construction of your lip would do yours. You will probably 

 admit that your own visage would present an appearance not very 

 engaging while concealed by such a mask : but it would strike 

 still more awe into the spectators were they to see you first open 

 the two upper jaw-like plates, which would project from each 

 temple like the blinders of a horse ; and next, having by means 

 of the joint at your chin let down the whole apparatus, and un- 

 covered your face, employ them in seizing any food that presented 

 itself, and conveying it to your mouth. Yet this procedure is 

 that adopted by the larvae provided with this strange organ. 

 While it is at rest, it applies close to and covers the face. 

 When the insects would make use of it, they unfold it like an 

 arm, catch the prey at which they aim by means of the mandibu- 

 liform plates (Jig. 101), and then partly refold it so as to hold 

 the prey to the mouth in a convenient position for the operation 

 of the two pairs of jaws with which they are provided." 



(339.) The metamorphoses of the gnat (Culex) are not less 

 interesting. The female deposits her eggs upon the surface of the 



* Introd. to Entom. vol. iii. p. 126. 



