INTRODUCTION. 



STEUCTUEB. 



In the insects composing the Sub-order Heteroptera the body 

 consists normally of 13 segments, of which the 1st is the Head ; the 

 2nd, 3rd, and 4fch are united to form the TJiorax ; and the remaining 

 9 are joined together to form the Abdomen. In the latter portion 

 some of tlie segments often become so amalgamated with or covered 

 by others as not to be distinguishable. The following concise 

 account of the principal parts of the external anatomy is given in 

 explanation of the terms used in the descriptions of the insects ; for 

 the minute and internal anatomy and the physiology, which do not 

 come within the scope of this book, we must refer to the works of 

 Kirby and Spence, Leon-Dufour, Burmeister, Amyot and Serville, 

 Kolenati, Fieber, Flor, &c. 



The Head. — On the upper surface of the head the portion before 

 the eyes is the Face, and the posterior portion is the Croicn. The 

 Face is divided by two longitudinal lines (sometimes deeply im- 

 pressed) into three parts or lobes, which vary in their relative pro- 

 portions ; sometimes the Crown is distinctly produced in front over 

 the face, and this prolongation is the Clypeus. On the crown are 

 2 simple Ocelli (sometimes wanting). On the side-margins of the 

 head are 2 immovable, compound Eyes. Before the eyes, sometimes 



7' 



