INSTRUMENT OF GRASSHOPPER. 233 



on the exterior by two membranaceous plates, usually circular 

 or oval ; and beneath them is a cavity, part of which seems 

 to open into the belly. These drums form, however, but one 

 portion of a compound instrument ; for, besides these, there is 

 attached to another drum-like membrane in the interior a 

 bundle of muscular strings; on pulling which, and letting 

 them go again, a sound can be produced even after the 

 animal's death. For the issue of this sound a hole is ex- 

 pressly provided, like the sound-hole of a violin, or the opening 

 in the human larynx. 



The chirp of the cricket, both of house and field, is said, by 

 Kirby, to be produced by the friction of the bases of the 

 tegmina, or wing cases, against each other, at their base ; but 

 these insects are also provided with their drums. In the 

 large green field cricket 1 this drum is described 2 as a round 

 plate of transparent membrane tensely stretched, and sur- 

 rounded by a prominent edge, or nervure. The instrument is 

 to be found in that part of the right wing-case which is folded 

 horizontally over the trunk, and is concealed under the left, 

 in which also there is a strong circular nervure corresponding 

 to the hoop of the drum beneath. The quick motion with 

 which these nervures are rubbed together producing a vibra- 

 tion in the membrane, is supposed to augment the sound. 



What .we call familiarly the singing or chirping of grass- 

 hoppers and locusts, is outwardly produced by application of 

 the hind shank to the thigh, rubbing it smartly against the 

 wing-cases, and alternating the right and left legs ; but these, 

 as well as the cicada and the cricket, are provided with their 

 " petits tambours," membrane-covered drums, or cavities of 

 somewhat varied construction, to augment the sound of ex- 

 terior origin. 



Be it here observed that the above-named professors of the 

 "joyeuse science" the cicada lyre-players the crickets of 



1 Acrida viridissima. (Vignette). 2 By De Geer. 



