NOISES OP INSECTS. 



321 



note, not unlike that of the goat-sucker ( Caprimulgus euro- 

 pcBus), but more inward. 1 I remember once tracing one by- 

 its shrilling to the very hole, under a stone in the bank of 

 my canal, in which it was concealed. We learn from Mr. 

 Newport, who, in his very valuable treatise on insects in the 

 Cyclopcedia of Anatomy and Physiology, has so admirably 

 illustrated their structure, both internal and external, that 

 this low jarring sound is owing to the shortness of the 

 nervures, and the much greater number of those on the 

 under side of the wing-covers being scored with the same 

 notches as in a file (p. 928.) ; pointed out in the crickets by 

 M. Groureau, who also saw them in the mole-cricket, but 

 seems to have overlooked their extending to so many of the 

 nervures as Mr. Newport has observed to be furnished with 

 them. 



Another tribe of grasshoppers (Acrida, Pterophylla, &c. 2 ) 

 — the females of which are distinguished by their long ensi- 

 form ovipositor — like the crickets, make their noise by the 

 friction of the base of their elytra. And the chirping they 

 thus produce is long, and seldom interrupted, which distin- 

 guishes it from that of the common grasshoppers (Locusta). 

 What is remarkable, the grasshopper lark (Sylvia locustella), 

 which preys upon them, makes a similar noise. Professor 

 Lichtenstein, in the Linncean Transactions, has called the at- 

 tention of naturalists to the eye-like area in the right elytrum 

 of the males of this genus 3 ; but he seems not to have been 

 aware that De Geer had noticed it before him as a sexual 

 character ; who also, with good reason, supposes it to assist 

 these animals in the sounds they produce. Speaking of 

 Acrida viridissima — common with us — he says, " In our 

 male grasshoppers, in that part of the right elytrum which is 

 folded horizontally over the trunk, there is a round plate 

 made of very fine transparent membrane, resembling a little 

 mirror or piece of talc, of the tension of a drum. This mem- 

 brane is surrounded by a strong and prominent nervure, and 

 is concealed under the fold of the left elytrum, which has also 



' Nat. Hist. ii. 81. 2 See Kirby in Zool. Journ. p. iv. 429, 



3 Linn. Trans, iv. 51. 



VOL. II. 



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