88 COLEOPTERA. 



SHIELD-WINGED INSECTS. ORDER COLEOPTERA. 



The Coleopterous insects are characterized by having four 

 wings, of which the anterior pair, always hard or leathery in their 

 texture, form two strong shields, beneath which the hinder pair 

 are lodged and protected. The front wings, or elytra* when in 

 repose, are always united by a straight edge extending along their 

 whole length. The hinder wings, which alone are adapted for 

 flight, are much larger than the elytra, and when not in use, are 

 folded transversely ; in a few species they are wanting, and then 

 the elytra are, as it were, soldered together. The tegumentary 

 envelope of these insects is always remarkably hard, and forms a 

 very substantial suit of armour. Their mouth is constructed for 

 the mastication of food, and is provided with a pair of strong 

 mandibles, a pair of maxillae bearing palpi, and a labium or lower 

 lip also bearing palpi. The abdomen is sessile, that is, is broadest 

 at the place where it joins the thorax. 



The metamorphosis which the Coleoptera undergo is complete. 

 The larva resembles a worm ; its body is soft, with the exception 

 of the head and the first segments of the body, which are of a 

 horny consistence ; it is generally furnished with three pairs 

 of horny legs, attached to the three first rings, but sometimes 

 these are replaced by fleshy tubercles ; there is, however, never 

 a greater number than six of these appendages. The pupa is 

 motionless and takes no food, its limbs being swathed together by 

 the external integument ; it is generally enclosed in a shell or 

 cocoon, composed of different substances joined together by a 

 viscid silky material ; sometimes it is naked. This is by far the 

 most numerous of all the insect orders : the number of species 

 already known is probably not much less than fifty thousand. In 

 order, therefore, more readily to arrange such a multitude, they 

 are divided into four sections, according to the number of joints 

 or articulations entering into the composition of their feet (tarsi]. 

 The sections so formed are as follows : 



1. The Pentamerans,t in which the tarsi of all the legs arc 

 composed of five joints. 



2. The Heteromerans, J in which the tarsi have five joints on 

 the tivo anterior pairs of legs, and only four on the hindmost pair. 



* L\vrpGv, elytron, a case. f Tr^re, pente,y?z^; /ufyos, meros, a joint. 



Jc'repoj, eteros, various ; //.<^>os, meros, a joint. 



