EXCRETORY SYSTEM IN DIGENEA. 



3 2 9 



firm Cort's data and, in supplementing and expanding these 

 data, to emphasize the writer's previous view (igiSa, 108) that 

 it seems "reasonable to recognize a complete series of larva 

 forms from those with a pharynx sphincter ... to the human 

 schistosome cercarise." 



Of the ten species of forked-tailed cercariae for which adequate 

 data are at hand with respect to the flame-cell structure, the 

 cercaria of Schistosoma japonicum presents the most simple 

 basic plan. Following the method previously used in this paper, 

 the flame-cell formula of this species is 4 = (2+2). That one 



6 7 



FIG. 6. Cercaria furcicauda nov. spec., ventral view, showing excretory and 



digestive systems. X 170. 



FIG. 7. Cercaria robusticauda nov. spec., ventral view, showing excretory and 



digestive systems. X 54. 



of these flame cells in each lateral circuit is found in the caudal 

 portion of the larva is incidental rather than fundamental. 

 The species Cercaria douthitti and C. elephantis of Cort represent 



