26 ORDER OF COLEOPTBRA. 



Order of COLEOPTBRA. 



The Ooleoptera, (a term composed of two Greek words, xoXeo<; a sheath, 

 and mepa wings,) commonly called beetles, are the most numerous divi- 

 sion of the mandibulate or gnawing insects. They are distinguished 

 from all other insects by the hard texture of their bodies, and by thgjjr 

 horny wing-covers, called elytra, which represent the upper pair of wings 

 of other insects. The elytra are not moved in flight, but only raised so 

 as to permit the free motion of the lower or true wings, and a few of the 

 chafers (Cetonice) do not even raise them during flight. They are gen- 

 erally hard, horny and inflexible, but in the lightning-beetles (Lampy- 

 ridcej and a few others, they are comparatively thin and flexible, but 

 never membraneous like the lower wings. The inferior or true wings 

 differ from those of almost all other insects in being folded crosswise, as 

 well as lengthwise, when at rest under their cases. The Buprestidse 

 and a few others form exceptions to this rule. A few kinds which live 

 under stones and in other dark places, and which have no occasion to 

 fly, have no wings under their elytra. 



Owing to the perfect development and the hard texture of the crust 

 or integument of the Coleoptera, and also to the circumstance that it is 

 not usually much obscured by hair, this part is made more use of in 

 classification than it is in any of the other orders. The upper side ex- 

 hibits the three divisions of the insect's body : the head, the thorax, and 

 the abdomen, covered by the elytra. Between the elytra, at their base, 

 or where thej^join the thorax, is almost always a small triangular piece 

 called the scutellum. On the under side, each of the principal parts is 

 seen to be composed of a considerable number of pieces usually soldered 

 together, and distinguished only by fine impressed lines called sutures. 

 These subdivisions and their names will be sufficiently understood, with- 

 out the necessity of a detailed description, by the annexed figure of one 

 of the ground-beetles fSarpalus caliginosusj and the accompanying ex- 

 planation, taken in connection with the general description in the be- 

 ginning of the work. 



EXPLANATION OF THE FOLLOWING FIGURE. 



The oblong narrow piece in the middle of the mouth, marked l, is the 

 ligula or tongue. At the extremity of the ligula are two little wings or 

 side pieces marked p p ; these are the paraglossm. The other parts of 

 the mouth are named in the figure, and have been described in the in- 

 troductory part of this work. The under side of the head, behind the 

 mentum or chin, is called the gula or throat. 



The under side of the thorax is divided into a considerable number 

 of pieces more or less distinct, and separated from each other by im- 

 pressed liiies called sutures. The middle portion is called the sternum 



