70 Gwynactlt Buchanan : 



The nephridia are supplied by vessels opening directly from 

 the hearts (Fig. 23 Af. Ne.), while the blood is brought back 

 in small vessels opening into the sub-intestinal (Ef. Ne.). Ben- 

 ham (6), in describing the vascular supply to the nephridium 

 in Lumbricus, says the course of the blood is along the com- 

 missural, which receives blood from the nephridia and body 

 wall, to the dorsal, which then supplies the alimentary canal. 

 Bourne (11) says blood passes from the nephridia to the sub- 

 intestinal, and from the alimentary canal plexus to the dorsal 

 vessel, in this agreeing with Vejdovsky. The valves (Figs. 21, 

 22a, 22b) are shown in section to be membranous, almost funnel 

 shaped structures, stretching across the vessel, with a circular 

 opening in the middle. The most marked sets are those in the 

 dorsal vessel at each mesentery, which are attached to a well- 

 marked muscular thickening on the wall ; and those leading 

 from the supra-intestinal to the hearts, which, however, do not 

 seem to be connected with any such thickenings. 



The branch from the dorsal vessel to the heart is also 

 guarded by a similar, though very small, valve, and the whole 

 structure has very little the appearance of a functional vessel. 



In the case of the dorsal vessel the action of the valve is 

 clearly that of guiding the blood forwards and preventing it 

 from flowing backwards. In the event of the blood attempt- 

 ing to flow backwards, it is evident that the pressure of the 

 fluid on the wall of the funnel would close the opening in the 

 latter. The valves leading towards the hearts are so small that 

 it is difiicult to determine their exact structure and relation- 

 ships. The valves guarding the entrance of the supra-intesti- 

 nal into the hearts have the convex face of the funnel facing 

 into the heart. Pressure of blood on the heart — that is, the 

 convex side — would close the small opening in the funnel. 



11. — Megascolex fielderi, Spencer. 



Pepichaeta fielderi, Sj-eiuer, P.lv.S. Virt., 1892. 



Plate XV., Fio- 11, and Plate XV] i, Fi- 24. 



DU=<cH'uni. The siiKjIt dorsal vessel is much swollen in seg- 

 ments 16-9, and runs forward to break up in the first segment. 

 At the posterior part there is a commissural vessel supplying 



