OF THE MOUTH. 159 



the insect to see objects immediately below it with the 

 small or more convex lenses, and objects at a greater dis- 

 tance with the upper or larger ones : this wonderful pro- 

 vision is one of those numberless instances of design which 

 render the anatomy of insects of such surpassing interest. 

 Petiolated eyes are those which are placed at the end of 

 distinct stalks, which are situated one on each side of the 

 head : this is a very rare and remarkable character in the 

 eyes of insects ; it occurs in a peculiar genus of flies 

 called Diopsis. The form of eyes is very various ; the 

 variations are expressed by the usual descriptive terms of 

 shape, as round, oblong, kidney-shaped, &c. 



Mouth. The mouth of an insect is situated below the 

 head, and generally projects slightly forwards. It consists 

 of an upper and lower Up, 6Soia Au4A u3 ,4 3 

 two mandibles, two feeler- 

 jaws, and a tongue. The up- 

 per lip or labrum, a, shaded 

 in the figure, corresponds 3 



closely with the same organ 



t 

 in vertebrate animals : it is 



a solid, horny plate, which 



arises from beneath the cly_ w1 ol 



. . " Mouth of fiipipteryx. 



pens and projects beyond 



it : it is articulated at its junction with the head, moving 

 freely in a vertical direction, and closing the mouth above : 

 its appearance is more uniform than that of any other organ 

 of the mouth. The uvula or hypopharynx is a valve at- 

 tached to the interior surface of the upper lip ; its office is 

 to close the throat. The hypopharynx is not to be disco- 

 vered in the generality of insects; it is, however, particularly 

 prominent in some kinds of wild bees. The throat or pha- 

 rynx is the opening immediately below the hypopharynx ; 

 it is the only passage for the food into the stomach. 



