268 J. E. WODSEDALEK. 



EXPLANATION OF FIGURES. 

 PLATE I. 



All drawings (except Figs. 2 and 3) made with a camera-lucida. X240. 



FIG. i. Palmen's organ in its relation to the tracheal system in the head of the 

 nymph H. inter punctata. X 60. 



FIG. 2. Sketch drawn from a specimen which had the organ removed and the 

 four tracheae broken off near their juncture with the main longitudinal tubes. 



FIG. 3. Sketch drawn from a nymph in which the tracheae were severed at 

 their point of contact with the organ. 



