THE BEETLE. 139 



insects without exception, that the thorax is composed 

 of three segments, an anterior, called the prothorax, a 

 middle one, the mesothorax, and a posterior, the meta- 

 thorax. To each of these is attached a pair of legs. 



The head of insects is provided with special organs, 

 called antennae ; they are a sort of horns of very varia- 

 ble form, and composed of rings articulated end to end. 

 The antennae are gifted with great mobility, and most 

 probably serve to enable the creature to recognize by 

 touch the nature of surrounding objects. In the beetle 

 these organs are terminated by a series of superposed 

 plates which unfold like the leaves of a fan. 



Beside the antennae and near the mouth are the eyes, 

 which have a structure altogether peculiar. They have 

 no eyelids, and their surface, which is very prominent 

 and bulging, presents the appearance of a hemisphere 

 cut in facettes. On examination with a microscope, or 

 even with a simple magnifying glass, it is found that 

 each facette corresponds to a distinct eye, and that the 

 entire eye is in reality composed of a large number 

 of little eyes placed very close together : sometimes 

 there are several thousand facettes. Independent of 

 these multiple eyes, several species have two or three 

 other eyes, which are simple, and arranged in the form 

 of a triangle in the forehead. These simple eyes are 

 called ocellae, to distinguish them from the compound 

 eyes, composed of facettes, which are the only ones pos- 

 sessed by the beetle. 



Underneath the head is the buccal orifice. As in the 

 crustaceans, this orifice is surrounded by modified limbs 

 that are used in mastication by insects that, like the 

 beetle, masticate their food. 



We distinguish a pair of mandibles, hard, horny, curved, 



