346 



ZOOLOO 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 antennas, palpi, and 

 abdominal appendages of dif- 

 ferent insects are seated mi- 

 nute sense organs of unknown 

 functions, though probably 

 either of smell or taste (Fig. 

 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. A, b, sense-organ on the ab- 

 dominal appendages of a fiy( Chrysopila); 

 c, sense-organ on the terminal joint of 

 palpus of Perla. Author del. 



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

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

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

 cle of the same ; M, 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- 



