SEA-FISHERIES LABORATORY. 279 



appendix is, at the greatest, about one-third of the entire 

 length of the animal. It is very retractile and easily 

 ruptured by undue pressure. 



The characteristic serrations on the margins of the 

 body, due to plications of the skin, were not clearly 

 seen. 



The main excretory channels are two ducts which 

 curve round from the anterior part of the body and meet 

 behind the ventral sucker, then pass down the mid 

 line of the body to the termination of the appendix as a 

 single channel. 



The ovary is situated about half-way between the 

 extremities, ventrally and a little to one side, and is nearly 

 spherical in shape. Immediately posterior to it are the 

 vitellaria. There are two principal lobulated masses. 

 In the specimen figured there are three lobes on one side 

 and four on the other. At the anterior extremities the 

 two vitelline masses are connected together by a short 

 bridge of tissue and from this a short duct connects with 

 the ovary. The shape of the vitellaria is far from 

 being constant, and little value can be placed on the 

 extent to which each lateral mass is lobulated. In some 

 specimens the sub-division was very much less than in 

 the figure. 



Over the middle part of the vitellaria was a rounded 

 structure which is apparently the receptaculum seminis. 

 Neither in preparations of the entire worm nor in section, 

 however, could the exact relations of this structure with 

 the vitellaria and oviduct be made out. 



The uterus in some specimens is very voluminous. 

 In no case did it descend into the appendix. It is 

 aggregated on the side of the body opposite to the ovary 

 and vitellaria. The ova are very uniform in shape, and 

 the diameters (0"025 x 0*01-5 mm.) agree very well with 



