212 HENRY LESLIE OSBORN 



age." Ill his illustration, as well as in this description, there is no 

 recognition of subcuticular vessels like those of Clinostomum. In 

 a study of the parasites infesting the frogs of Minnesota I have 

 happened to find specimens of this genus. The study of living 

 and sectioned material of this form demonstrates that, while there 

 is an extensive system of vessels derived by branching from the 

 collecting vessels and one which bears considerable resemblance 

 to that found in Clinostomum, encircling subcuticular vessels are 

 not developed. 



A third form with somewhat similar branching excretory ves- 

 sels was encountered at Chautauqua, New York. In the livers 

 of sun-fishes certain cysts were found which contained immature 

 flukes belonging to the holostomes. These forms are peculiar in 

 having a broad thin anterior body region bearing a resemblance 

 to the foot of a gasteropod mollusc and posteriorly a globular mass 

 carried vertically over it. The excretory pore is located at the 

 summit of the latter. In the thin anterior part there are a median 

 and two lateral longitudinal vessels, extending from which are 

 branching vessels extending everywhere in the foot, anastomosing 

 and forming a complete network. All of the vessels of this sys- 

 tem contained minute highly refractive droplets, similar in appear- 

 ance to those found in the excretory cavities of Clinostoma 

 which had been recently liberated from bass cysts. In the living 

 worms masses composed of these droplets were discharged from 

 time to time from a point located at the posterior end of the body, 

 the excretory pore, thus indicating that the passages are members 

 of the excretory system. In life the droplets were in constant 

 motion in the vessels, coursing rapidly in all directions as they had 

 been seen doing in Clinostomum. 



This observation, taken in connection with the presence of such 

 droplets in. the encysted specimens of Clinostomum and their 

 absence in the heron specimens of Clinostomum and the free 

 living Cephalogonimus, constitutes an argument in favor of the 

 supposition that the droplets are composed of chemical wastes. 

 In an encysted organism these must be disposed of in a way that 

 will prevent their damaging the animal, accordingly they cannot 

 be discharged from the body in the ordinary manner but must be 



