170 SCIENCE PROGRESS. 



are unsegmented animals, with a well-marked alimentary 

 canal, the Cestoda are divided by a number of constric- 

 tions into a series of segments, and possess no trace of an 

 alimentary canal. When, therefore, we find a parasitic 

 platode that has an unsegmented body and no trace of 

 an alimentary canal, we are naturally anxious to learn 

 whether its affinities are more closely connected with the 

 former group or the latter. Such an animal is Caryophyl- 

 laeus, a form that is found parasitic in the intestines of a 

 certain fresh-water fish. 



We are indebted to Dr. H. Will 1 of Retelsdorf for a 

 careful study of the anatomy of Caryophylla;us mutabilis 

 parasitic in the intestines of the bream of the Warnow 

 River, and for a very strong confirmation of the views 

 previously held by most naturalists that this interesting 

 parasite, although showing some primitive features, is, 

 nevertheless, a true Cestode. 



The principal points brought out by Will's paper are 

 briefly as follows : The excretory system is in very marked 

 contrast to that of most of the Cestodes. It consists of 

 four main ascending trunks, which collect the secretion of 

 capillaries from the parenchymatous tissues of the body, and 

 pass forwards from the trunk towards the head. In the 

 region of the neck these four trunks unite into two, which 

 in the head break up into a complicated anastomosis. 

 Passing backwards from the cephalic anastomosis are ten 

 descending trunks, which unite together at the excretory 

 pore, situated at the posterior end of the body. 



In the arrangement of the single group of sexual organs, 

 Caryophyllaeus approaches that of the Bothriocephalicke, a 

 family which many naturalists consider to be more primitive 

 in their anatomy than the true tapeworms. In the Taeniadse 

 the uterus is a branched organ, which communicates only with 

 the genital pore by the vagina. In the Bothriocephalidse, 

 on the other hand, the uterus communicates with the 

 exterior by a separate os uteri, situated some distance apart 



1 Will, H., "Anatomie von Caryophyllaeus mutabilis," Zeitschr. f. wiss. 

 Zool., lvi. i. 



