PLATE 23 



Fig. 37. Cercaria germ ball, showing beginning of excretory system. X 190. 



Fig. 38. Cercaria germ ball, showing formation of tail and further develop- 

 ment of excretory system. X 190. 



Fig. 39. Further development of cercaria. Note bulblike enlargements in 

 region of bladder. X 190. 



Fig. 40. Immature cercaria, showing union of bladder tubes. X 190. 



Fig. 41. Immature cercaria, showing further union of bladder tubes. X 190. 



Fig. 42. Various stages of movement of tube bulbs of bladder as shown in 

 figure 39. X 350. 



Fig. 43. Lateral view of cercaria, showing formation of oral and ventral 

 suckers. X 178. os., oral sucker; vs., ventral sucker. 



Fig. 44. Lateral view of mature cercaria. X 127. os., oral sucker; vs., 

 ventral sucker. 



Fig. 45. a., body spines of cercaria on side between oral and ventral suckers. 

 X 529; 6., dorsal view of one spine. X 2117; c, lateral view of one spine. 

 X 2117. 



Fig. 46. Encysted agamodistome (cyst). X 194. 



[384; 



