12 ART S. 1. IKEDA : THREE NEW AND 



body-end. Further, the vas deferens does not run free in the 

 body-cavity as it does in other Bonellian males, but s»tands 

 throughout its entire length in connection with the ventral body- 

 wall, only the four long funnel-stalks projecting free into the 

 body-cavity. As determined from serial cross-sections, the vas 

 deferens in the anteriormost parts is imbedded quite in the body- 

 wall, running between the nerve-cord and the body-cavity [v.d.^ 

 fig. 12). The wall is internally lined by an endothelium and 

 externally invested by a dense layer of reticular connective-tissue 

 fibers ; the lumen is filled up with spermatozoa, which fact greatly 

 facilitates the tracing of the course of the duct. Posteriorly, the 

 latter gradually recedes from the nerve-cord and comes to pursue 

 its course in a longitudinal ridge that raises itself from the 

 body-wall along the cœlomic floor [v.d. in fig. 11). In the 

 ridge just referred to, the vas deferens sends forth dorsally 

 three branch canals in short succession ; its posterior elongation 

 after giving ofiP the third brancli may be called the fourtli ; so 

 that it may be said that there exist in all four branch canals 

 into w^hich the vas deferens divides up posteriorly. Of the three 

 canals cut across and indicated by the letters v.d. in fig. 12, 

 the two upper ones are sections of the first and the second branch 

 respectively, while the lowest is that of the posterior continua- 

 tion of the main vas deferens before giving out the third branch. 

 Fig. 13 represents a more posterior cross-section of the worm ; 

 in it we see the first and second branches (I. and II.) as free 

 tubes — in the section both cut obliquely crosswise — in the body- 

 cavity ; the third and fourth branches (III. and IV.) pursue 

 their course still within the narrow ridge of the body-wall just 

 above the ventral nerve-cord. A short distance still more pos- 

 teriorly, all the four branches are met with as free tubes as 



