Oil Stichocotyle nepliropis CunniiiKliHin, a para!>ite of the American lobster. 463 



or less club-shaped extremity may be seen in the living worm to float 

 about in the Huids within the intestine moving for considerable 

 distances one way and the other borne by the movement of the fluids 

 within the intestine and appearing almost like a free cell. They were 

 indeed mistaken by Cunningham for such. They show various degrees 

 of vacuolatiou, the vacuoles being chiefly near the free ends of the 

 cells and either appearing as a single rounded cavity (Fig. 22) or 

 being broken up into parts and distributed through the cytoplasm of 

 the cell, as shown in Fig. 26. 



From the way in which these elongated entodermal cells overlie 

 one another in the intestine, it often happens that in sections they 

 present an api)earance similar to that shown in PL 31, Fig. 23. It 

 was probably some such appearance as this which led Cunningham 

 to state that these cells "form sometimes more than one layer." 



Backward from its union with the pharynx the intestinal wall 

 lacks for a short distance its epithelial lining, as shown in PI. 29, 

 Fig. 5. This is probably associated with the movements of the pharynx. 

 In the living specimen observed under a compressor this part of the 

 intestinal wall may be seen to form distinct lateral folds extending 

 from the two sides inward and meeting in the middle (PI. 29, Fig. 6); 

 the folds act as a valve to interrupt communication between the cavity 

 of the intestine and that of the pharynx. 



Excretory System. 



The excretory organs present several rather peculiar features and 

 ofler evidence concerning the affinities of this somewhat aberrant worm 

 as direct as is to be obtained from any single system. 



The system is made up of paired excretory vesicles, which extend 

 forward on each side of the intestine to points opposite the pharynx. 

 At the posterior end they unite with each other back of the intestine 

 and open by a dorsal pore near the caudal extremity of the body. 

 Into the anterior ends of these vesicles open the smaller tubules of 

 the system. 



In treating of this system I shall describe successively these 

 parts — flame-cells, capillaries, collecting tubules and caudal vesicle 

 — into which the system may be divided in Trematodes generally. 



The flame -eel Is are entirely indistinguishable in sections, but 

 may be made out with certainty in the smaller and more transparent 



