252 



MR. B. F. CUMMINGS ON 



5, 6, and 7 there is a single tergite, broad and deep. The chitin, 

 on the dorsal surface of segments 8 and 9, is thin and trans- 

 parent. The sternites on segments 2 to 7 are of the same form 

 and disposition as the tergites, excepting that on each of seg- 

 ments 2 and 3 there are two sternites, the first in segment 3 



Text-figure 4. 



Polyplax oxyrrliynclms. Male. X 67'5. a. Sternal plate. 



being of a triangular shape. The sternum of segment 8 is 

 occupied by the genital plate, which, on each side behind, is 

 produced into a narrow band of chitin connecting the plate with 

 the thickened margin of the terminal segment. The pleurites of 



