296 ARTICULATA: LKTSECTA. 



Section of the Eye of the Cockchafer (Melotontha B, a portion of A more highly 



vulgarise, highly magnified. magnified, 



a, facets of the corneoe ; &, pyramids surrounded with pigment ; c, fibres of the 

 optic nerve ; d, trunk of the optic nerve. 



The ocelli constitute the only visual organs of most of 

 the Myriapods, of all the Arachnids, and of the larvse 

 of many of the Hexapod Insects. The number of ocelli 

 in adult insects is generally three. (See Fig. 362.) 



The real eyes of Insects are compound, being made up 

 of a very many simple eyes. During the development or 

 growth of the insect the simple eyes of the larv r se increase 

 in number, and at length coalesce to form the compound 

 eye. The number of facets or corneas in the compound 

 eye is very great in some kinds of insects, 3,650 having 

 been counted in the eye of a butterfly. The form of the 

 facets is generally hexagonal, but in some species it is 

 quadrangular. 



As to the organs of hearing, smell, taste, and touch, but 

 little is positively known. The an tenure seem to serve 

 the purpose of feelers, and it is believed that they are 

 also connected with the sense of hearing. But it should 

 be remarked here that Siebold found an auditory appara- 

 tus in the fore legs of some species of grasshoppers. 



