346 



ZOOLOG Y. 



sound, heard and appreciated by individuals of the other 

 sex. Any insect which produces a sound must be supposed to 



have ears to hear the sound pro- 

 duced by others of its species. 

 In the antennae, palpi, and 

 abdominal appendages of dif- 

 ferent insects are seated mi- 

 nute sense organs of unknown 

 functions, though probably 



either of sme11 or taste ( Fi s- 



290). 



The ears (or auditory sacs) of the locust are situated, one 

 on each side, on the basal joint of the abdomen, just be- 



Fig. 290.^!, b, sense-organ on the ab 

 dominal appendages of a fly ( Chrysopila) 



Fig. 291. Ear of a locust (Caloptenus italicus) seen from the inner side. T, tym- 

 panum ; TE, its border ; o, u, two horn-like processes ; bi, pear-shaped vesicle ; n, 

 auditory nerve ; ga, terminal ganglion; st, stigma ; m, opening and m/ closing mus- 

 cle of the same ; J/, tensor muscle of the tympanum-membrane. After Graber. 



hind the first abdominal spiracle (Fig. 279). The ap- 

 paratus consists of a tense membrane, the tympanum, sur- 

 rounded by a horny ring (Fig. 291). " On the internal sur- 



