204 



ORTHOPTERA 



8tli and 9 th dorsal 

 (7 and 8 in Fig.). 



processes, which are differently shaped according to the sex of 



the individual. 



The structure of the abdomen in the earwig has given rise to 



considerable discussion. In Fig. 103 we reproduce Westwood's 



diagram of it as seen fully distended 

 in a female specimen ; in this state the 

 minute spiracles can be detected, though 

 in the normal condition of the body 

 they cannot be seen, being placed on 

 the delicate membranes that connect 

 the chitinous plates. Westwood's inter- 

 pretation of the structure was not, how- 

 ever, quite correct, as the part which 

 he considered to be the first dorsal 

 plate is really the second ; so that the 



Fig. 103. Lateral view of For- segments numbered 7, 8, 9 in our 

 jicuiaauricuiariai.. Female., fiaure are really 8, 9, 10. The com- 



abdonien distended showing ^ ... 



5piracies, s, and the small mou earwig IS interesting as exhibit- 

 plates jjjg^ jj-^ ^j-^ imperfect state, the union 

 of the first dorsal plate of the abdo- 

 men with the thorax ; a condition which is carried to so 

 great an extent in the Hymenoptera as to quite obscure the 

 nature of the parts, and which has consequently given rise to 

 much perplexity and discussion. We repre- 

 sent this structure as seen in the common 

 earwig in Fig. 104, where a represents the 

 pronotum, 1) the inesonotum, c the metanotum, 

 d the first,/ the second abdominal segment ; 

 e being a delicate membrane of considerable 

 size that intervenes between the two, and 

 which is more exposed than are the corre- 

 sponding membranes connecting the subse- 

 quent rings ; a condition similar to that which 

 is found in Cimbex, Cephus, and some other 

 Hymenoptera. 



On the under surface of the abdomen of the 

 earwig the full number of 10 plates cannot be superficially dis- 

 tinguished ; but it is found by dissection that in the female the 

 short eighth and ninth dorsal rings are joined on the ventral aspect 

 by a delicate membrane, while the tenth ventral is of a less delicate 



Fig. 104. Dorsal por- 

 tions of the middle 

 segments of body of 

 Forficida aurictd- 

 aria (tegmina and 

 "wings removed). 



