33 2 



ERNEST CARROLL FAUST. 



vessel which empties into the bladder at the side of the median 

 collecting tubule of the tail, just behind the island of Cort. 



In all of these furcocercarise, as well as in others where the 

 flame cells have not been worked out, there is a forking of the 

 caudal excretory tubule at the junction of furci with tail trunk. 

 The forked tubules empty through simple pores at the sides or 

 distal extremity of the tail-furci. Comparison of the point of 

 opening of these pores in various species shows that in the cer- 

 caria of Schistosoma japonicum, C. douthitti and C. elephantis 

 the openings are at the tips of the furci; that in most other forms 

 they are half-way out on the sides; but that in C. furcicauda the 

 outlets are near the origin of the furci (Fig. 6). Thus the writer 

 sees no consistent correlation between the flame-cell formulae 

 and the point of outlet of the caudal tubules. 



In furcocercarias the excretory system is apparently always 

 provided with the island of Cort. 



Analysis of the flame-cell fundaments in this group shows a 

 simple basic plan and an unusually complete series of stages 

 from the simplest combination of units (cercaria of S. japonicum) 



TABLE i. 



METHODS FOR DISTINGUISHING THE BETTER KNOWN FORKED-TAILED 



CERCARI/E. 



Species. 



Flame-cell Formula. 



Digestive Tract. 



Eye-spots. 



Cercaria of Schistosoma 



japonicum 



Cercaria douthitti 



Cercaria elephantis 



Cercaria furcicauda . . . . 

 Cercaria emarginatce. . . . 



Cercaria douglasi 





 Cercaria robusticauda . . . 



Cercaria quattuor- 



solenata 



Cercaria rhabdocaca . . . . 



Cercaria gigas 



4 = (2 +2) 



6 =(3 +3) 



6 =(3 +3) 



6=(2+2+2) 



7 =(3 +2 +2) 



7=(3+2+2) 



7=(l +2+2+2) 



8=(2+2+2+2) 



10 =(2+2 + 2 + 2 + 2) 



10 =(2 + 1 + 1 + 1 + 1 



pharynx absent, 5 pairs 



mucin glands, 

 pharynx absent, 5 pairs 



mucin glands. 

 pharynx absent, 25-30 



pairs mucin glands, 

 pharynx present, 2 pairs 



mucin glands, 

 pharynx present, mucin 



glands? 

 pharynx present, 2 pairs 



mucin glands, 

 pharynx glandular, 6 



pairs mucin glands, 

 pharynx present, no 



mucin glands, 

 pharynx present, rhab- 



docoel gut, 3 pairs 



mucin glands, 

 pharynx absent, mucin 



glands many, of two 



kinds. 



absent. 



present. 



present. 



absent. 



absent. 



absent. 



absent. 



absent 



absent. 



present. 



