350 University of California Publications in Zoology [Vol. 19 



but that they do so is certain and that wastes pass out only in liquid 

 condition is almost equally certain. Evidently the concretions are 

 produced about as fast as dissolved and eliminated, since I have never 

 seen an active cercaria without these concretions filling this entire 

 part of the bladder. In the region of the anterior end of the pharynx 

 these tubular divisions of the bladder turn completely round, forming 

 a very characteristic area (fig. 47, t.a.). 



Here the ascending tubes of the bladder (le) join the concretional 

 tubes of the bladder (Id). The difference between these two divisions 

 of the bladder is principally physiological, i.e., in terms of the presence 

 or absence of concretions. These latter divisions, as stated, are the 

 ascending tubes of the bladder (le). These divisions of the bladder 

 pass ventral to the concretional tubes of the body (Id) at the anterior 

 end, but later come to lie on the outside of and parallel to it. In the 

 region of the posterior end of the ventral sucker, a collecting tubule 

 (2a), joins the ascending tubes of the bladder (le). This collecting 

 tubule is joined shortly by a bulblike accessory collecting tubule (3c), 

 into which three capillaries enter that drain the wastes by means of 

 three flame cells from the region of the acetabulum. A short distance 

 anteriorly three other capilaries join this collecting tube (2a). These 

 capilaries unite singly some distance apart with the collecting tubule. 

 However, we might consider that the part of the tubule between capil- 

 laries 4x and 6x represents the accessory collecting tubule (3b). This 

 seems probable because the accessory collecting tubule (3c) is reduced 

 to a mere bulb and because even here the capillaries do not join exactly 

 at one place. At the anterior end of the collecting tubule (2a) , three 

 other capillaries are received which drain the wastes from the oral 

 region. Here again the accessory collecting tubule (3a) has either 

 been eliminated or is represented by the tubule between capilaries 2x 

 and 3x. In this latter group the capillaries are even farther apart 

 than the ones forming the group just preceding. This loss or modifi- 

 cation of the accessory collecting tubules 3a and 3b is shown graph- 

 ically by comparing text figure No. 1 with figure 47. Thus to collect- 

 ing tubule (2a) three groups of three flame cells each are joined, 

 directly or indirectly, by accessory collecting tubules. 



At the posterior end of the body, the ascending tube of the bladder 

 (le) receives three collecting tubules (2b, 2c, and 2d). One of these 

 collecting tubes (2b) is considerably longer than the others. It 

 receives two sets of three capillaries and flame cells, numbers 10, 11, 

 12, and 13, 14, 15. The most anterior group of capillaries arises nearly 



