180 THE CAUSES WHICH PROPAGATE 



forward, '^ Wu£ ! wuf ! •'^ The effeminacy of this grasshopper 

 has come under the observation of Fischer, who relates : "I have 

 sometimes seen the male stretch out his fore feet on the ground 

 with a most ridiculous gesture, sway his body backwards and 

 forwards, erect and wave his antennse, and employ all his art of 

 flattery/^ Yersin says the note is rapidly trilled and silvery, 

 lasting' from three to four seconds. The teeth in the femoral 

 limse Herr Graber gives as one hundred and fifty. The male of 

 the minute and agile Gompliocenis ligutatus, L., I have observed 

 singing on bare sand-flats at Calais, during July, and later on 

 near Largs on the Clyde. The powerful femora move swiftly 

 as many as from eleven to twenty-one times on the elytra, and 

 at the fourth double stroke the sound is borne on the ear; it 

 then increases, and again lapses away, leaving a floating echo in 

 the air. The teeth on the ridges of the femora number from 

 one hundred and thirty to one hundred and forty. Largest at 

 the lower end, they decrease in size and become more thickly 

 placed toward the upper ; so that when they strike on the scapular 

 vein, the double note may be compared to running up and down 

 the octave, but the illusion of the stridulation increasing and 

 diminishing in intensity is more probably due to a variation in 

 the celerity of the movement of the femora. Yersin says of 

 this species that it emits from nine to twelve notes of about a 

 second^s duration, and that these are slower and stronger at the 

 conclusion — " Vrrreee." The legs vibrate imperceptibly, and 

 press on the elytra only during their forward movement. 



Dr. Scudder gives us the stridulation of some of the Neartic 

 grasshoppers adapted to musical notation. One [Stenohothrus 

 curtipennis) produces about six notes per second, and continues 

 them from one and a half to two and a half seconds ; another 

 {S. melanopleurus) emits from nine to twelve notes in about 

 three seconds. The music of the latter when in the shade is 

 slower. 



The South African genus Pneumora forms a third group of 

 the order, distinguished in their mode of stridulation from the 

 preceding. The males of these pass the inner side of the posterior 

 femora over a little semicircular row of oblong horny teeth (/") 

 placed on the skin of the abdomen, which in this sex is inflated 

 like a bladder, a circumstance that has earned the species the 



