JANUARY. 9 



maxillcety which they gnaw their food ; and HAUSTELLATA, 

 where these jaws are replaced hy minute laminge forming a 

 kind of sucker, haustellum, which is received into a sheath, 

 the insects of this class procure their food by suction, 

 either from animal or vegetable substances. The other parts 

 of the mouth are the palpi, or feelers, small movable ap- 

 pendages placed on each side, which vary in size and 

 number ; the promuscis or- rostrum being the part forming 

 the mouth in many of the sucking insects ; the proboscis, or 

 sheath, which contains the trophi, or organs of the mouth 

 in Dipterous insects ; and the antlia, or suckers, the organs 

 constituting the principal part of the mouth in Lepidoptera. 

 This organ is generally very slender ; in the family Sphin- 

 gidce it is long, in Papilionidw much shorter ; in a state 

 of rest it is rolled spirally between the palpi. 



The eyes of insects are of two kinds, simple and com- 

 pound, horny, immovable, and unprotected by any eyelid. 

 When closely examined, they are found to consist of a great 

 number of minute hexagonal lenses, each of which forms a 

 distinct organ of vision ; of these, the common Fly possesses 

 4,000, the Silkworm Moth 6,236, and some Butterflies 

 17,355 : when detached from the head and cleaned, they 

 are found to be as clear as crystal. The celebrated natu- 



