96 ILLIXOIS BIOLOGICAL MONOGRAPHS [376 



EXPLANATION OF PLATE 



POLYSTOMA ORBICULARE 



Fig. 7- Frontal section. X 35- 



Fig. 8. Frontal section of ootype and beginning of uterine duct. X i8s. 



Fig. 9. Frontal section of ootype and end of right vitello-vaginal canal, five 



sections ventral to Figure 8. X 185. 

 Fig. 10. Frontal section, o6type region of same specimen as Figures 8 and 9, 

 showing ovary, uterus, oviduct, uterine duct, genito-intestinal canat 

 and vas deferens. X 140. 

 Frontal section showing vitellaria and origin of vitelline ducts with 



granular secretion in the cells and duct. X 87. 

 Frontal section thru cirrus sac at the juncture of the shanks and roots of 

 the genital hooks, showing the genital papillae cut across, and a sec- 

 tion of the duct from the uterus at the bottom of the figure. X 250. 

 Reconstruction of male genital apparatus from sagittal sections. X 140. 

 Frontal section thru uterus showing embryo in stage of a morula-like 

 mass of cells. X 700. 



