CALIFORNIAN COLEOPTERA. 63 



sixth dorsal segments, that on the fourth segment showing 

 boldest. Each of these bands is seen with a high power to 

 consist of cernuous bristles set in oblique rows, alternating 

 and interlacing Avith one another; the point of each bristle 

 is bent downward, forming a bow, and the band, as a whole, 

 gains elasticity by the pressure of each bristle thus bowed 

 against the next in the series. The rubbing of these three 

 bands against the edges of the elytra produces the stridula- 

 tion. The examination of species of the allied genus 

 Bolbocerus shows the same stridulating power, but the 

 outline of the bands in each case so differs as to show spe- 

 cific characters. 



