Chap. X.] ORTHOPTERA. 343 



won." " Dr. Scudcler was able to excite one of these in- 

 sects to answer him, by rubbing on a file with a quill. 30 

 In both sexes a remarkable auditory apparatus has been 

 discovered by Von Siebold, situated in the front legs." 1 



In the three Families the so\mds are differently pro- 

 duced. In the males of the Achetidse both wing-covers 

 have the same structure ; and this in the field-cricket 

 (Gryllus campestris, fig. 10) consists, as described by 

 Landois, 32 of from 131 to 138 sharp, transverse ridges or 

 teeth (st) on the under side of one of the nervures of the 

 wing-cover. This toothed nervure is rapidly scraped 

 across a projecting, smooth, hard nervure (r) on the upper 

 surface of the opposite wing. First one 

 wing is rubbed over the other, and then 

 the movement is reversed. Both wings 

 are raised a little at the same time, so 

 as to increase the resonance. In some 

 species the wing-covers of the males are 

 furnished at the base with a talc-like 

 plate. 33 I have here given a drawing (fig. 

 11) of the teeth on the under side of the FlG n _ Teeth of 

 nervure of another species of Gryllus, viz., ^Sticu^cfrom 



G. domesticus. Landois). 



In the Locustidas the opposite wing-covers differ in 

 structure (fig. 12), and cannot, as in the last family, be in- 

 differently used in a reversed manner. The left wing, 

 which acts as the bow of the fiddle, lies over the right 



29 ' The Naturalist on the Amazons,' vol. i. 1863, p 252. Mr. Bates 

 gives a very interesting discussion on the gradations in the musical appa- 

 ratus of the three families. See also Westwood, ' Modern Class.' vol. ii. 

 pp. 445, 453. 



30 « Proc. Boston Soc. of Nat. Hist.' vol. xi. April, 1868. 



31 ' Nouveau Manuel d'Anat. Comp.' (French translat.), torn. i. 1850, 

 p. 567. 



32 ' Zeitschrift fur wissenschaft. Zoolog.' B. xvii. 1867, s. 117. 



33 Westwood, ' Modern Class, of Insects,' vol. i. p. 440. 



