392 NOISES OF INSECTS. 



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 promi- 

 nent, run here and there very iri'egularly with various in- 

 flexions, describing curves, spirals, and other figures dif- 

 ficult and tedious to describe, and producing a variety 

 of areolets of different size and shape, but generally 

 larger than those of the female: particularly towards the 

 extremity of the wing you may observe a space nearly 

 circular, surrounded by one nervure, and divided into 

 two areolets by another''. 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 uppennost 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. 

 The merry inhabitant of our dwellings, the house- 

 cricket {Gryllus domesticus), though it is often heard by 

 day, is most noisy in the night. As soon as it grows 

 dusk, its shrill note increases till it becomes quite an 

 annoyance, and interrupts conversation. When the male 

 sings, he elevates the elytra so as to form an acute angle 

 with the body, and then rubs them against each other 

 by a horizontal and very brisk motion''. The learned 

 Scaliger is said to have been particularly delighted with 

 the chirping of these animals, and was accustomed to 



" Compare De Geer, jii. 512. 



*■ De Geer, iii. 517. See also White, Not. Hut. ii. 76;— and Rai. 

 Hist, Ins. 63. 



