84 ILLINOIS BIOLOGICAL MONOGRAPHS [530 



EXPLANATION OF PLATE 



Pig- 55- Cercaria douthitti, ventral view. X 195. 



Fig. 56. Cross section of Cercaria douthitti thru eye-spots. X 433. 



Fig. 57. Diagram of the excretory system of Cercaria douthitti in the region where 



the tail joins the body. X about 400. 

 Fig. 58. Cross section of Cercaria douthitti thru the acetabulum. X 433. 

 Figures 59 to 62. Cross sections of Cercaria douthitti showing the passage of the 



ducts of the cephalic glands thru the oral sucker. X 433. 

 Fig. 63. Section thru a sporocyst of Cercaria douthitti while still included in the 



snail's liver. X 433. 

 Fig. 64. A portion of a sporocyst of Cercaria douthitti. X. 44. 

 Fig. 65. A portion of a sporocyst of Cercaria isocotylea. X 44. 

 Fig. 66. Sporocyst of Cercaria isocotylea. X 44. 



Fig. 67. Stylet of Cercaria isocotylea from ventral and side view. X 433. 

 Fig. 68. Cercaria isocotylea, ventral view. X 311. 



