THE ABDOMEN AND LEGS. xHx 



The Abdomen. 



This part of the insect occurs cyHndrical, fusiform, 

 flattened, roundly truncate, or nearly square. It is 

 usually composed of seven, or sometimes of eight, horny 

 rings, joined by the interposing connexivum or pliable 

 membrane. Usually one more ring can be counted on the 

 dorsal aspect than on the ventral ; but at the extremity 

 of the abdomen a kind of case or envelope occurs, 

 which in the females contains a complicated apparatus 

 of saws and files, and in the males an equally elabor- 

 ated series of prehensile hooks, suited to secure the 

 couplement of the sexes at the fitting season. The 

 typical number of segments in insects is generally 

 recognised as thirteen, but in many cases two or more 

 rings become united into one, and thus the visible 

 number is inconstant. 



,- As the female carries her partner, the claspers are 

 at such times very efficient during the performance of 

 their vigorous leaps from bush to bush. The envelope 

 above aUuded to is called the " pygophore " by Fieber, 

 which, with its valves and styles, will be described 

 elsewhere, and may be seen drawn in many plates. 



In Cicadetta the basal abdominal rings are covered 

 by the semilunar plates, which protect the sounding 

 cavities with their tense tympana. On the ventral aspect 

 six stomata with fringed entrances may be counted on 

 each side ; they are placed on the edges of the connex- 

 ivum, but they are not always visible. The abdomen 

 can be thrown into longitudinal folds, whereby its shape 

 may become either cylindrical or flattish. The viscera 

 in the winged insects are mostly very attenuated, and 

 often seen to be nearly void of nutritive matter. 



The Legs. 



In the Tettigidae leaping is chiefly effected by the 

 legs, but considerable assistance is also given by use 

 of the wings. 



e 



