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 



to the 



FIG. 170. Inner face of femur . , . , . , , . 



of sienobothrus, male, run along the side that is nearest 

 showing line, a-a, of musical body (Fig. 170); the tegmeii or wing-case 



beads. (After Landois, . J ^ 



magnified three times.) has projecting veins, one of which is 

 slightly more prominent, and has a sharp 



edge ; by scraping this edge over the beads of the femur the wing- 

 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 l that rudi- 

 mentary musical organs do 

 exist in the females of various 



FIG. 171. A, Some of the knobs projecting 

 from the surface of the femur of Stenobo- 

 thrus melanopterus, male ; B, same of the 

 female. Highly magnified. (After Graber.) 



species of Stenobofhrus (Fig. 



171, B). 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 Vcrh. zool.-bot. Ges. Wien, xxi. 1871, p. 1097. 



