INTRODUCTION. XI 



Anoplura, placing the inandibulate families with Orthoptera, and 

 the suctorial Pediculidaj with Heniiptera. 



Having thus exhibited the elementary characters upon which 

 the orders are based, the special subject of the present treatise 

 may now occupy the attention of the student. 



In order that the body of the work may be made intelligible to 

 the beginner, it will be necessary to make a brief exposition of 

 the external anatomy of Coleopterous insects, before attempting 

 to define the numerous families which compose the order. The 

 three regions, the head, thorax, and abdomen, will therefore be 

 taken up in succession. 



HEAD. 



« 

 The anterior portion of the body is called the head ; it varies 

 greatly in form, and is joined by membrane to the prothorax. 

 Usually the hind portion is but slightly narrowed, and enters the 

 anterior part of the prothorax; sometimes the part behind the 

 eyes is suddenly narrowed and constricted, forming a neck, or 

 gradually narrowed and much prolonged, articulating with the 

 pi'othorax by a semiglobular condyle, as in some Carabidaa and 

 the Brenthida3. 



The surface of the head consists of a solid horny plate; above, 

 it is frequently marked by a single suture, running transversely 

 between or in front of the antennae ; this is called the clypeal or 

 frontal suture. The portion in front of this suture, when dilated 

 so as to project over the mouth, as in many Scarabgeidae, is called 

 the clijpeus; when small it is named cpistoma, and is sometimes 

 membranous or coriaceous, instead of horny like the rest of the 

 surface. The anterior portion of the head is sometimes prolonged, 

 so that the distance between the eyes and mouth parts is greater 

 in length than the rest of the head; when thus formed the head 

 is called rostrate, and the prolonged portion the rostrum or heak\ 

 The ro.s(;?'«Hi varies greatly in form and length; it is often not 

 narrower than the head and awn shorter, rarely, as in Balaniinis, 

 very slender, almost filiform, and as long as the entire body. Th(^ 

 presence of the rostrum is (piite general in the sub-order Rhvn- 

 chophora, but not characteristic of it, as the rostrum is often 

 absent here and present in other isolated genera of the Coleop- 

 terous series. 



