PLATE XXI. 



PAGE 



Fig. 153- Stentor cisruleiis, xioo, - - - - -94 

 Fig. 154. Stentor roeselii (?), beginning of oblique fission, 



X 100, --------94 



Fig. 155. Stentor rceselii (?), further development of oblique 



fission, X 100, ------ 94 



Fig. 156. Stentor roeselii (?), oblique fission almost com- 

 plete, X 80, - - - - - - - - 94 



Fig. 157. Gyrocoris oxyura, x 500, .... g6 



Fig. 158. Halteria grandinella, x 800, - - - • 96 



