NOISES OF INSECTS. 495 



of other insects, my further observations will be confined to the tribes 

 lately mentioned, the Gryllina, &c., and the Cicadce. 



No sound is to me more agreeable than the chirping of most of the 

 Gryllina, Locustina, &c. ; it gives life to solitude, and always conveys to my 

 mind the idea of a perfectly happy being. As these creatures are now very 

 properly divided into several genera, I shall say a few words upon the song 

 of such as are known to be vocal, separately. 



The remarkable genus Pneumora whose pellucid abdomen is blown up 

 like a bladder, on which account they are called Blaazops by the Dutch 

 colonists at the Cape in the evening, for they are silent in the day, 

 make a tremulous and tolerably loud noise, which is sometimes heard on 

 every side. 1 The species of this genus have a claim to the name of Fid- 

 dlers, since their sound is produced by passing the hind-legs, which are 

 furnished with a series of smooth elevated ridges, and may be called the 

 fiddle- sticks, over a number of short transverse elevated ridges, of a similar 

 though slightly different structure, on the abdomen, which may be called 

 the strings? 



The cricket tribe are a very noisy race, and their chirping is caused by 

 the friction of the cases of their elytra against each other. For this pur- 

 pose there is something peculiar in their structure, which I shall describe 

 to you. The elytra of both sexes are divided longitudinally into two 

 portions ; a vertical or lateral one, which covers the sides ; and a horizon- 

 tal or dorsal one, which covers the back. In the female both these por- 

 tions resemble each other in their nervures ; which running obliquely in two 

 directions, by their intersection, form numerous small lozenge-shaped or 

 rhomboidal meshes or areolets. The elytra also of these have no elevation 

 at their base. In the males the vertical portion does not materially differ 

 from that of the females ; but in the horizontal the base of each elytrum 

 is elevated so as to form a cavity underneath. The nervures also, which 

 are stronger and more prominent, run here and there very irregularly with 

 various inflexions, describing curves, spirals, and other figures difficult and 

 tedious to describe, and producing a variety of areolets of different size 

 and shape, but generally larger than those of the female ; particularly to- 

 wards the extremity of the elytrum you may observe a space nearly cir- 

 cular, surrounded by one nervure, and divided into two areolets by 

 another. 3 The friction of the nervures of the upper or convex surface of 

 the base of the left-hand elytrum which is the undermost against those 

 of the lower or concave surface of the base of the right-hand which is 

 the uppermost one, will communicate vibrations to the areas of membrane, 

 more or less intense in proportion to the rapidity of the friction, and 

 thus produce the sound for which these creatures are noted ; which, how- 

 ever, according to M. Goureau, in his elaborate essay on the stridulation 

 of insects, is chiefly owing to the circumstance of one of the strong ner- 

 vures called by him the bow (Parchet) being striated or cut transversely 

 like a file; whence it has a much more powerful action on another 

 collection of nervures which he calls the treble-string (la chanterelle}. 41 



The merry inhabitant of our dwellings, the house-cricket (Gryllus do- 

 mesticus), though it is often heard by day, is most noisy in the night. As 



1 Sparrman, Voy. i. 312. 



2 Charpentier in Silbermann's Revue Entom. iii. 314. 



3 Compare De Geer, iii. 512. 



4 Ann. Soc. Ent. de France, and Entom. Mag, v. 94. 



