OF THE ANTENNA. 155 



to insects, the mandibles are furnished with distinct feelers. 

 The skull consists of four portions ; the superior arched 

 upper surface, A, is tlie crown, epicranium or vertex, the 

 inferior surface, B, in the figure at page 153, is the throat 

 or gula, and the lateral surface, CE QE, are the eyes or 

 oculi. 



The epicranium is frequently divided by a sutural line, 

 passing across the forehead from eye to eye. When this 

 is the case, the portion so separated, ae, and which imme- 

 diately covers the mouth, and in many instances the an- 

 tennae also, is called the shield or clypeus ; the gula also is 

 often separated by a similar sutural line ; in this case, the 

 anterior portion adjoining the mouth is called the chin or 

 mentum. There are one, two, or three minute, transparent, 

 highly convex lenses situated on the crown of the head, 

 into which they are closely soldered; these are called 

 simple eyes or ocelli : all insects, except beetles, seem to 

 possess them more or less perfectly, and in several species 

 even of beetles ocelli have been detected ; the situation 

 and comparative size of these is shown by the three black 

 spots in the skull of Ripipteryx ; their use has never been 

 ascertained, but entomologists agree in considering them 

 organs of vision. 



Antenna. The cranial feelers or antenna, y y, arise 

 from the skull in front of the ocelli, between the eyes, 

 sometimes above and sometimes below the clypeus ; they 

 are freely articulated with the skull, and moveable in every 

 direction; they are composed of numerous joints. In 

 length, stoutness, shape and clothing, the antenna of in 

 sects are very various ; their variations are the subject of 

 nomenclature ; and, moreover, afford excellent characters 

 for descriptions. Antenna are called setaceous (fig. 1), 

 attenuantes, when they are long, throughout slender, and 

 yet taper gradually to the apex, and the union of the 



