72 ILLINOIS BIOLOGICAL MONOGRAPHS [518 



EXPLANATION OF PLATE 



Figures i to 4. Free hand drawings of stages in the process of encystment of 



Cercaria urbanensis. X about 70. 

 Fig. 5. Mature Cercaria urbanensis, ventral view. Cystogenous glands not shown. 

 X 140. 



Posterior locomotor projection of Cercaria ephemera. From Ssinitzin. 



Posterior locomotor projection of Cercaria imbricota. From Looss. 



Posterior locomotor projection of Cercaria urbanensis. X 433. 



Cross section of the tail of Cercaria urbanensis. X 433. 



Immature redia of Cercaria urbanensis... X 88. 



Mature redia of Cercaria urbanensis. X 88. 



Mature redia of Cercaria urbanensis, showing constrictions. X 44. 



Cross section of immature redia of Cercaria urbanensis. X 433. 



