INSTRUMENT OF GRASSHOPPER. 233 



on the exterior by two membranaceous plates, usually circular 

 or oval 5 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). * By De Geer. 



