EXCRETORY SYSTEM IN DIGENEA. 



331 



O 



C. furcicauda in having three flame cells instead of two in the 



first (anterior) group. The formula for these species is 7 = 



(3 + 2+2). In Cercaria robusticauda (Fig. 7) there are the 



same number of flame cells as in C. emarginattz and C. douglasi, 



but the size of the anteriormost is evident 



proof of its double nature. Hence the 



formula for this species is 7 = (i +2+2+2). 



One of these cells runs into the tail. This 



species is transitional between the larvae 



with seven flame cells in three groups and 



C. quattuor-solenata nov. spec. 



C. quattuor-solenata (Fig. 8) represents a 

 condition in which a full additional flame- 

 cell unit has been provided. Its formula 

 is 8 = (2 + 2 + 2 + 2). Incidentally, the 

 main collecting tubule in this species has 

 been shortened to a minimum, while the 

 four secondary tubules have been length- 

 ened accordingly. 



In Cercaria rhabdoc&ca nov. spec. (Fig. 

 9) five fundamental flame-cell groups are 

 found, so that the formula is 10 = (2 + 2 



+ 2+2+2). 



The flame-cell arrangement in Cercaria 

 gigas (Fig. 10) is apparently unrelated to 

 any of the foregoing species. Ten flame 

 cells have been found on each side of the 

 body of the cercaria and one in the tail. 

 By inspection the formula would seem to be 



IO = (2 + I +I + I +I+3 + I). That FIG. 10. Cercaria gigas 



this may constitute a seven-fold grouping, Faust ' dorsal view ' show ' 



... , , ...... ing excretory system on 



in which two of the groups have divided, is rightsideof body . x 540 . 

 supported in part by the fact that the single 



cells are somewhat larger than the cells of the units where the 

 division has taken place, but the evidence is not entirely con- 

 vincing. In the mature cercaria of this species the flame cell 

 in the tail has no direct connection with the cells or tubules of 

 the body proper. Its outlet is through a simple longitudinal 



