118 ILLINOIS BIOLOGICAL MONOGRAPHS [118 



DESCRIPTION OF PLATE 



Fig. 134. — Cercaria biflexa; ventral view, showing salivary gland cells. X 105. 



Fig. 135. — Cercaria biflexa: ventral view, showing excretory system. X 105. 



Fig. 136. — Cercaria biflexa; lateral view of collar spines. X 330. 



Fig. 137. — Cercaria biflexa; redia of worm. X 170. 



Fig. 138. — Cercaria biflexa; detail of three flame cells in cephalic region. X 540. 



Fig. 139. — Cercaria biflexa; genital cell masses. X 170. 



Fig. 140. — Cercaria trisolenata; posterior end of redia. X 540. 



Fig, 141. — Cercaria biflexa; posterior end of redia. X 540. 



Fig. 142. — Cercaria gracillima; ventral view. X 230. 



Fig. 143.— Cercaria gracillima; excretory system. X 350. 



Fig. 144. — Cercaria gracillima; dorsal view of trunk, showing eye-spots and salivary glands 



X 350. 

 Fig. 145. — Cercaria gracillima; detail of flame cell of excretory system. X 750. 

 Figs. 146, 147. — Cercaria gracillima; sporocysts; Fig. 146, x 14; Fig. 147, X 21. 

 Fig. 148 A-G. — Cercaria gracillima; stages in development. X SO. 



