On Stichocotyle nephropis Cmiuingliam, a paraaite of the American lobster. 469 



guanin ') gave uegative results. After treating the coucretious with 

 strong nitric acid, there still remained behind a skeleton or organic 

 matrix, which preserved the form of the body and was destroyed only 

 by strong sulphuric acid. 



The excretory vesicles with their contained concretions and 

 portions of the collecting tubules were seen and described by Cun- 

 ningham. He observed the long cilia within the collecting tubules, 

 but did nut determine the point at whicli the tubules communicate 

 with the vesicles. Flame-cells and capillaries he did not observe. 



The relation of the excretory vesicles of Stichocotyle to those of 

 Aspidogaster has already been mentioned. A close similarity between 

 the other parts of the excretory system is also evident in these two 

 forms. In A^pidogaster the excretory vesicles extend forward only as 

 far as the anterior end of the compound ventral sucker, and the 

 main collecting tubes, after extending forward to very near the anterior 

 end of the animal, must make a turn in the vicinity of the pharynx 

 and extend backward for a short distance before uniting with them. 

 In Stichocotyle the vesicles extend forward nearly to the anterior end 

 of the body, and consequently the collecting tubes do not make a 

 turn backward, but open into the vesicles opposite the pharynx, in a 

 region corresponding with that at which the tubules of Aspidogaster 

 turn upon themselves^ to extend backward. These differences are, 

 however, not important, and do not obscure the essential similarity. 

 The long vibratile cilia in the collecting tubules, as described by 

 VoELTzKOW, also agree closely with those which I have observed in 

 Stichocotyle. Voeltzkow states that in Aspidogaster the distribution of 

 the excretory tubules of the two sides of the body is not symmetrical : 

 all of the sexual organs are supplied by branches from tubules of the 

 left side. Whether the same asymmetry in the distribution of these 

 tubules occurs in Stichocotyle does not appear clear. It is more dif- 

 ficult to determine the exact source of each tubule in Stichocotyle^ 

 since the organs are placed much closer together than in Aspidogaster. 

 It will be seen from Fig. 23 (PI. 31) that one of the branches of the 

 left side evidently arises in the vicinity of the ovary and another near 

 the left testis. The right testis seems, however, to be much more 

 intimately related to a branch from the right side, and a branch from 

 the right side also extends to the oviduct. In view of these facts. 



1) Sections of the material on tiic .slide were heated with strong 

 nitric acid and ammonia was then added. 



