98 ILLIXOIS BIOLOGICAL MONOGRAPHS [378 



EXPLANATION OF PLATE 



POLYSTOMA OPACUM 



Fig. 15. Entire specimen, extended, ventral view. X 20. 



Fig. 16. Reconstruction of genital apparatus from toto preparation and cross 



sections. X 50. 

 Fig. I". Hook from genital coronet. X SSO. 

 Fig. 18. Frontal section thru the anterior sucker and pharynx, showing in section 



nerve commissures and vitellaria. X 60. 

 Fig. 19. Cross section of body thru uterus and cirrus sac. X 60. 

 Fig. 20. Cross section of body thru the testis. X 60. 

 Fig. 21. Cross section thru the anterior pair of bothria. X 60. ' 



