470 ^' ^- Nl^KERÄON, 



we must couclude , 1 thiuk, that the asymmetry m tlie distributioü 

 of these tubules does not occur in Stichocotyle to the same extent as 

 in Aspidogaster. But though the same dilierences between the two 

 sides of the body do not occur here, it nevertheless appears to be 

 true in this species, that there is not strictly bilateral symmetry in 

 the arrangement of the collecting tubules. All things considered, it 

 seems evident that there is a very close resemblance between the 

 excretory systems of the two forms. 



The excretory system of Cotijlogaster, described by Monticelli 

 I '92), has certain features of interest in this connection. From the 

 dorsally placed excretory pore a common duct, or caudal vesicle, ex- 

 tends obliquely forward and ventrad for a short distance, and then 

 divides into two cornua , which extend forward one on either side. 

 Furthermore, this common portion of the excretory vesicle is lined by 

 a portion of the "ectoderm", which is reflected inward as far as the 

 bases of the lateral cornua. Since Monticelli applies the term ecto- 

 derm to the layer which I have called cuticula, it will be seen at 

 once that these portions of the excretory system in Cotylogaster agree 

 very closely with those of Stichocotyle. The more minute portions of 

 the system are not sufficiently known in Cotylogaster to furnish a 

 basis for making comparisons. 



The Sexual Organs. 



The complete sexual apparatus cannot be described, since no 

 worm has been obtained in a sufficiently mature condition for all 

 parts of the sexual organs to be developed. Nevertheless the more 

 advanced specimens have the fundaments of most of the sexual organs 

 present, and though the final form and position of all of the organs 

 cannot be determined, enough can be made out to enable one to 

 arrive at a fairly definite notion of this system, and to give one some 

 ground, not possessed by Cunningham, for comparing this with other 

 Trematode parasites. Somewhat more trustworthy conclusions concern- 

 ing the relationships of Stichocotyle are perhaps possible from this 

 increased knowledge of its structure. 



In the worms which I have studied there are present the funda- 

 ments of the ovary and oviduct, the testes and the vitellary glands. 

 The ovary (PI. 29, Fig. 3 oa; PI. 31, Fig. 23 oa) is situated about 

 midway between the anterior and the posterior end of the body, nearly 

 in the median plane and ventrad of the intestine. It is approximately 

 retort-shaped, with the larger part upon the left side. Fronj the 



