XV111 INTRODUCTION. 



as to form a joint near the extremity, whereby the wing can be 

 folded entirely under the elytra; in some genera with short elytra 

 the wings are extended straight along the dorsal surface of 

 the abdomen. The venation is subject to variation in different 

 genera, but no results of importance for classification have yet 

 been obtained by the study of these organs. Frequently they 

 are wanting, in which case the elytra are usually united closely, 

 or connate. 



Legs. — The first joint of the legs, or that by which they are 

 attached to the body, is called the coxa, and is received in appro- 

 priate cavities ; the anterior coxal cavities are surrounded by the 

 presternum and adjoining pieces, and are frequently open behind, 

 and rarely in such cases completed by the close apposition of the 

 mesosternum. 



The middle coxa? are surrounded by the meso- and metasternum, 

 and by the episterna of the mesothorax ; when these last do not 

 reach the metasternum the intervening space is occupied by the 

 inner extremity of the epimera of the mesothorax, which are then 

 said to attain the coxae. 



The hind coxeb are placed between the metasternum and the 

 first segment of the abdomen ; the latter extends along the outer 

 edge anteriorly so as to reach the side pieces of the metathorax, 

 though frequently this junction can be seen only on raising the 

 elytra. 



The form of the eoxas is of the greatest importance in distin- 

 guishing the families. 



At the outer extremity of the anterior coxae is seen in some 

 families an accessory piece called a trochantin; when the protho- 

 racic breathing pore, or stigma, or spiracle is visible, it is in the 

 same vicinity. Still more rarely the middle coxa? have a similar 

 trochantin. 



At the extremity of the coxae is a small piece called the tro- 

 chanter ; it varies in form, being usually situated in the axis of 

 the thigh, and is more or less obliquely cut off; in many families 

 the trochanters of the hind pair are quite prominent at the inner 

 margin of the thighs, and connected with them only at the base. 



The first long piece of the legs is called the thigh, or femur ; 

 following it is the tibia. The form of the legs varies greatly in 

 different families; being either fitted for walking, ambulatorial ; 



