INSECTS : "WmGS AND THEIE APPENDAGES. 99 



angles to the remainder, over the hack, so that the one 

 partly overlaps the other. The musical organ consists 

 of a hard glassy ridge in front, behind which is a trans- 

 parent membrane, which appears tightly stretched over 

 a semicircular rim, like the parchment of a drum, an- 

 swering in structure and in function to the part so com- 

 pared in the cricket. 



This Gryllus I found would crink freely, when held 

 in my fingers, provided I held it by the head or thorax, 

 so as not to interfere with the freedom of the wing- 

 cases ; though these needed only to be partially opened, 

 the bases being merely slightly separated without af- 

 fecting the general contiguity. The two glassy ridges 

 were rubbed across each other, making the sharp crink. 

 Ordinarily this was done thrice, three distinct but 

 rapid crossings making the sound represented by the 

 word " Katedid ; " but occasionally the insect gave but 

 a single impulse, uttering as it were but one syllable of 

 the word. 



The Locusts and Grasshoppers, however, do, it ap- 

 pears, make use of their hind legs in producing their 

 crink. If you look at this Grasshopper's leg, you will 

 see that the thigh is marked with a number of trans- 

 verse overlapping angular plates, and that the shank 

 carries a series of short homy points along each side. 

 The iasect when it crinks, brings the shank up to its 

 thigh, and rubs both to and fro against the wing-sheaths, 

 doing this by turns with the right and left legs, which 

 causes the regular breaks in the sound. The drum, on 

 which this rubbing vibrates, has been described by the 

 anatomist, De Geer : — " On each side of the first seg- 

 ment of the abdomen," says he, " immediately above 

 the origin of the posterior thighs, there is a consi- 



