not shown in the drawing. The other appa- 

 ratus is seen through the plates. 



Fig. 18. Copied from Haller's drawing of the apparatus 

 below the plates after the plates have been 

 removed. The parts marked with diagonal 

 or transverse lines are chitinous, and are 

 coloured red in Haller's drawing. Haller's 

 explanation of the figure is (bp) space left by 

 the cutting away of the plates which com- 

 menced here ; (k) spoon-shaped hair ; (cm) 

 chitinised muscle ; (el) excretionary pockets. 

 As to the correctness of this see page 291. 



