350 INSECTA. 



the remarkable difference: "Conceive," says 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 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 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 conforma- 

 tion 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 mandibuliform plates (fig. 147, A), 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." 



(915.) The metamorphoses of the Gnat (Culex) are not less inter- 

 esting. The female deposits her eggs upon the surface of the water, in 

 which her offspring are destined to pass the earlier periods of their 

 existence, gluing the ova together at the moment of their extrusion, 

 so as to unite them into a boat-like mass (fig. 177, A) of such beautiful 

 construction that the little bark swims secure from injury even during 

 the roughest weather. The individual eggs are of a conical form 

 (fig. 177, B, a, 6, c), and are closed at their inferior extremity by a kind 

 of lid (el), provided to give egress to the mature embryo. The larva (c), 

 represented upon a magnified scale at E, bears not the slightest resem- 

 blance to the perfect insect, and is provided with a singular modification 

 of the respiratory apparatus adapted to its habits. The head is large, 

 and carries two ciliated organs (g </), which by their movements bring 

 food towards the mouth ; the thorax is even larger than the head, and 

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



