PLATE 24 



Fig. 47. Mature cercaria showing detailed arrangement and pattern of 

 excretory system. X 33.3. la„ caudal division of bladder; lb., muscular sac 

 of bladder; lc. muscular descending tube of bladder; Id., concretional descend- 

 ing tube of bladder; 7<„ ascending tube of bladder; 2a., 2b., 2c, 2d., collecting 

 tubules; 3a., 3b., 3c, 3d., 3e., 3f., 3g., 3h., accessory collecting tubules; 1-24, flame 

 cells; cs., collar spines; ta., triangular area. 



Erratum. On the lower right-hand side of figure 47, the figure "3" should 

 be inserted before the letter "f." 



