178 On the Sound Organs of the Green Cicada. 



air-cliambers of the sounding apparatus. I separated the 

 abdomen, produced the skirr in it, and then passed a bristle 

 through the metathoraic stigma for a distance of nearly half 

 an inch along the tracheid. 



(6.) There was no connection between the times of the 

 rise and fall of the cover for the stigma of the mesothorax 

 and the sounding of the rattle. 



To work out the question fully we need, further — (1) to 

 trace the development of the organs in the pupa, which is 

 rather difficult to obtain; (2) to compare the adult organs 

 of the Green Cicada with those of the other species of the 

 family. I believe that a graduated series of forms might be 

 obtained in which, as in the successive stages of growth of 

 an individual, we might trace the gradual progression of 

 these singular sound-organs, from simple beginnings to the 

 highly elaborated apparatus of the Cyclochila AustralasioB. 



EXPLANATION OF PLATE. 



Fig. 1. Cyclochila Australasice. Male insect, natural size. 



(a) Stridulating organ of left side. 

 Fig. 2. Side view of same, enlarged. Both pairs of wings 



have been removed, and also the opercular or protecting 



plates. (a) Rattle-membrane or stridulating organ; 



(6) great tension membrane of abdominal segment; 



(c) tension membrane of metathorax. 

 Fig. 3. View of separated abdomen from before, (a h) As 



before; (m) great muscles; (t) tendinous slips of same; 



(p) opercular plates covering stridulating organs. 

 Fig. 4. View of great muscles from behind, (b m) As before. 

 Fig. 5. Internal view of abdomen divided in longitudinal 



median section, from the left. (a h m) As before ; 



(o) plate-like terminal of right muscle. 

 I am indebted to my accomplished friend and colleague, 

 Mr. Frank Goldstraw, for the drawings in this Plate. 



