290 University of California Publications in Zoology [Vol. 19 



The common collecting tubes (c.c.t.) extend forward diagonally from 

 the bladder, pass ventrad to the testes and receive the anterior and 

 posterior collecting tubes (a.c.t., p.c.t.) at the level of the ventral sucker. 

 Each anterior and posterior collecting tube receives three accessory 

 collecting tubes (ac.c.t.), each of which in turn receives a group of 

 three capillaries (c). The positions of the accessory collecting tubes 

 and their capillary groups is shown in figure 5. In each capillary 

 group the accessory collecting tube divides into two divisions, one 

 of which forms directly a capillary which ends in a flame cell and 

 the other further subdivides into two capillaries and their flame cells. 

 In every group the paired capillaries go to one surface of the body 

 and the single capillary to the other. The dorso-ventral arrangement 

 of the capillaries of any particidar group varied in different indi- 

 viduals and no regularity in this respect could be discovered. The 

 significance of the two-one arrangement in the capillary groups in 

 relation to the development of this type of system was discussed in my 

 description of the excretory system of Cermria polyadena (Cort, 

 1919). The formula for the excretory system of Margeana calif or- 

 niensis is the same as that for Cercaria polyadena, 2 X 6 X 3 = 36 

 (Cort, 1919). 



Homologies op the Excretory System 



Of the six adult distomes described by Looss with the " 2-6-3 ' : 

 formula (Cort, 1919) for the excretory system, two, Haplotnetra 

 eylindracca (Zeder) and Opisthioglyphe ranae (Frolich), are now 

 placed (Odhner, 1910, 22 and 23) in the family Plagiorchiidae Liihe 

 syn. Lepodermatiidae Odhner. The other four species, Pleurogenes 

 medians (Olsson), Pleurogenes claviger (Rudolphi), Prosotocus con- 

 fusus Looss, and Anchitrcma sanguincum (Sonsino), are placed by 

 Odhner (1910, 76-77) in the family Lecithodendriidae Odhner. The 

 first three of these species which are closely related form the basis 

 of tin 1 subfamily Pleurogenetinae Looss. A comparison of the excre- 

 tory systems of these six distomes with that of Margeana calif or niensis 

 will show how fundamental are the homologies. The excretory system 

 of Haplometra cylindriacea is fully described and figured by Looss 

 (1894, p. 68, pi. 8, fig. 163). The excretory system of this species 

 corresponds more closely to that of Margeana californiens-is than those 

 of any of the other five species mentioned above. The most important 



