INSECTS IN GENERAL. 45 



ject artfully put in the way of its flight ; and it seems 

 probable that the extended membrane with which the 

 head of this animal is furnished, may be the means of con- 

 veying to the senses some communication from surrounding 

 objects by the elasticity of the air. But this is mere conjec- 

 ture, however probable, and we are unable to apply this 

 modus operandi to our own faculties ; there may however, be 

 something similar to this in insects ; they appear to us to see 

 with opaque eyes, and they may smell, hear, and feel, with- 

 out the aid of particular organs appropriated to each of 

 these faculties, or their antennae may serve them in a way 

 unknown to us in the enjoyment of most or all of their senses. 

 When we consider the extent and almost universality of 

 antennae among insects, we may at least fairly conclude that 

 in some way or other, or probably in many, they are essen- 

 tial to the enjoyment of their existence. 



The eyes of insects are widely different from those of the 

 other classes of the Animal Kingdom. They are divisible 

 into simple and compound eyes ; the former are very large, 

 and the whole surface is reticulated, with a minute tubercle 

 or lens between each reticulation ; the latter, like the eyes of 

 the vertebrata, form but one tubercle or lens of the entire 

 eye. 



All the coleoptera, and the diurnal lepidoptera, have two 

 compound eyes only, but these are sometimes divided across, 

 and appear as if double, as in the gyrini. The orthoptera, 

 hemiptera, hymetioptera, neuroptera, and diptera, have, with 

 a few exceptions, two compound with three simple eyes placed 

 between them. The exceptions comprehend the ephemera, 

 some species of the phrygania, which have only two very 

 large simple eyes. The hemerobia, and the antlions, more- 

 over, have not simple eyes : no winged insect therefore is de- 

 prived of compound eyes. 



