3O ETHEL NICHOLSON BROWNE. 



EXPLANATION OF PLATE III. 



Notonecta insulata. Fig. 21, metaphase of first division showing 14 chromo- 

 somes, two small ones in the center. Figs. 22, 23, anaphase of first division, side 

 view, two small pairs in the center. Figs. 24, 25, metaphase of first division showing 

 13 chromosomes, one small one in the center. Fig. 26, initial anaphase of first 

 division, side view, one small pair in the center. 



