44 INSECTS. 



rnitive violin with bow, string, and sounding-board, 

 is to be found in the fore wings. 



This instrument is most conspicuous in the crickets. 

 It consists of a clear space in the wing-cases, or fore- 

 wing, consisting of a tense membrane eucjosed by strong 

 and prominent nervures ; near this lies a strong nerve or 

 ridge, with a toothed, file-like surface. This file (the 

 bow), most prominent on the upper surface of the wing 

 which underlies, and on the under surface of that which 

 overlaps, plays, when the wings are rubbed together, 

 upon the raised ribs, causing a strong vibration in the 

 drum -like membrane, or sounding-board, beside them, 

 and thus producing the sound. 



Figure 19 shows the drum and file (or sounding-board 



Base of under side of wing-case of green Grasshopper (Acrida 

 viridissima) magnified. 



and bow) in the left wing of the green grasshopper. 

 Fig. shows the instrument in the right wing (A) of 

 another species, Acrida brachelytra, in which one of the 

 strings crosses the sounding-board. B is the left wing, 

 on which in this species is the file or bow. C is the file 

 or bow more highly magnified. In the common house 

 cricket the sounding-board is divided by nervures into 

 several areas of various sizes and shapes, and the sound 

 is supposed to be influenced by this circumstance. 



