105 ILLINOIS BIOLOGICAL MONOGRAPHS [106 



DESCRIPTION OF PLATE 



Fig. 20. — Cercaria pellucida; sagittal section thru pharynx and gut of redia, with prepharynx 



organ retracted. X 330. 

 Fig. 21. — Cercaria pellucida; transverse section thru body in region of posterior locomotor 



pocket glands. X 170. 

 Fig. 22. — Cercaria pellucida; optical view of the proliferation of the germ-balls from the 



posterior germinal epithelium of the redia. X 330. 

 Fig. 23. — Cercaria pellucida; central nervous system, typical for the trioculate species of 



monostome cercariae. X 330. 

 Fig. 24. — ^Yoimg Cercaria pellucida; oblique section thru ganglion mass, sho';nng connection 



of eye-spots with brain center. X 330. 

 Fig. 25. — Cercaria konadensis; dorsal view. X 105. 

 Fig. 26. — Redia of Cercaria konadensis. X 34. 



Fig. 27. — Cercaria konadensis; detail of paired group of caudal gland cells. X 540. 

 Fig. 28. — Cercaria konadensis; genital cell masses in region of ootype. X 540. 

 Fig. 29. — Cercaria konadensis; detail of excretory bladder and posterior locomotor pockets. 



X 238. 

 Fig. 30. — Cercaria konadensis; optical view of the germinal rachis of the redia. X 330. 

 Fig. 31. — Cercaria konadensis; sagittal section thru aspinose prepharynx of the redia. X 330. 

 Fig. 32. — Mature Cercaria urbanensis Cort; transverse section thru tail, showing caudal gland 



cells. X 330. 

 Figs. 33, 34. — Cercaria urbanensis; stages in differentiation of caudal gland cells from ordinary 



parenchyma cells. X 330. 

 Fig. 35. — Cercaria urbanensis; detail of excretor>' vesicle and posterior locomotor pockets. 



X 238. 

 Fig. 36. — Early germ-balls of Cercar /a «rJa»e«5J5; oblique section thru brain mass and lateral 



eye-spot, showing ectodermal origin of pigment cup, and connection with optic cells 



of brain. X 730. 

 Fig. 37. — Oblique longitudinal section thru Cercaria pellucida, showing detail of nerve 



endings. X 730. 



