86 



THE CANADIAN ENTOMOLOGIST. 



produce the rasping chirps previously described. The figure herewith 

 shows the position of the first pair of legs in stridulating. (Fig. 5.) 



The figures given are largely 

 diagrammatic, for the purpose of 

 bringing out the structural details 

 of the tonal apparatus. Figure 6 



Fig. 6. 



shows the coxal plate from the 

 side, and gives a good idea of its 

 shape and proportional size. One 

 side only of the prosterum is 

 given in figure 7 to show the 



Fig. 7. 



slit-like elongated coxal cavity. 

 As may be gathered from the two 

 figures, this structure allows con- 

 siderable vertical but limited 

 lateral motion, and, in fact, 

 Ranatra can lay the first pair of 

 legs against the upper or lower 

 side of the body with ease. The 

 inner surface of the hollowed 

 coxal plate is shown in figure 8, 



-C 



) 



Fig. 5 



Fig. 8. 



but only the mere shell, to show 

 the position of the roughened 



