284 



ACRIDIIDAE 



and extremely numerous. The pair of testes is united in a 

 single envelope. The form and arrangement of the ovaries 

 is remarkable (Fig. 169); the egg- tubes are united by the con- 

 vergence of their terminal threads into a single mass ; outside of 

 each ovary there extends a large calyx, into which the tubes 

 open ; each calyx is prolonged at its extremity, and forms a long, 

 convoluted tube. 



Acridiidae possess structures for the production of sound, together 

 with others that are, no doubt, for hearing. The chirping of grass- 

 hoppers is accomplished by rubbing together the outer face of the 

 upper wing and the inner face of the hind 

 femur. This latter part bears a series of 

 small bead-like prominences placed on 

 the upper of the two lower ridges that 

 run along the side that is nearest to the 

 body (Fig. 170) ; the tegmen or wing-case 

 has projecting veins, one of which is 

 slightly more prominent, and has a sharp 

 this edge over the lieads of tlie femur the wing 



Fig. 170. — Inner face of femur 

 of SteaohothruSy male, 

 showing line, a-a, of musical 

 beads. (After Landois, 

 magnified three times.) 



edge ; by scraping 

 is thrown into a state of vibration and a musical sound is produced. 

 The apparatus for producing sound was for long supposed to be 

 confined to the male sex of grasshoppers ; it was indeed known 

 that females made the move- 

 ments appropriate for producing 

 music, but as they appeared to 

 be destitute of instruments, and 

 as no sound was known to 

 follow from their efforts, it was 

 concluded that these were 

 merely imitative. Graber has, 

 however, discovered ^ that rudi- 

 mentary musical organs do 

 exist in the females of various 

 species of Stfnohothrus (Fig. 

 171, P.). It is true that in 

 comparison with those of the male (Fig. 171, A) they are 

 minute, but it would appear that they are really phonetic, 

 though we can hear no sounds resulting from their use. 



Graber considers that the musical pegs of Acridiidae are 



1 FerJi. r.ool.-hot. Ges. fFiai, xxi. 1871, p. 1097. 



Fig. 171. — A, Some of the knobs projecting 

 from the surface of the femur of Stenobo- 

 thrus 'inelanoplerus, male ; B, same of the 

 female. Highly magniiied. (After Graber.) 



