468 ALFRED GIBBS BOURNE. 



These vessels going to the vesicle of the nephridium have 

 two origins ; the first branch passes directly to its more anterior 

 portion, the second bifurcates, one portion ramifying upon the 

 internal portion of the vesicular wall, the other passing ven- 

 trally becomes connected with a small botryoidal network, but 

 terminates by anastomosing with the anterior branch of the 

 next following latere -abdominal vessel. 



These two vessels form a rich network upon the walls of the 

 vesicle, giving rise to a small trunk, which, passing forwards 

 parallel to the vesicle duct, breaks up into capillaries upon the 

 posterior limb of the main lobe of the nephridium (for the 

 arrangement of these and all the nephridial vessels, see my 

 figures of the nephridium, loc. cit.). 



The nephridium thus receives a double blood supply from 

 the lateral vessel, a direct supply anteriorly, coming from the 

 latero-abdominal vessel, and an indirect, posteriorly, arising 

 from the capillary network of the vesicular wall. 



The latero-abdominal branches also supply, according to 

 Gratiolet, the epididymis, the ovaries, and the copulatory 

 organs, male and female, but not the testes (see below). 



The Capillary System of the Nephridia communicates 

 on the one hand with the " cutaneous " dorsal networks, on the 

 other with the ventral sinus. 



The first communication is established by tortuous ramifica- 

 tions collecting upon the outer (dorsal) border of the main 

 lobe and running dorsally to anastomose with any of the three 

 '^cutaneous " dorsal networks. 



The second communication is established by an important 

 system of vessels described for the first time by Gratiolet ; these 

 arise between the two portions of the main lobe of the ne- 

 phridium, and, receiving branches from the apical lobe and 

 testicular lobe, pass alongside the latter on to the surface of 

 the testis and dilate there, forming the so-called '^moniliform 

 hearts" described by Brandt. 



It is in these dilatations that the funnel of the nephridium 

 of Hirudo, which I shall describe below, and which has escaped 

 the notice of all previous observers, is lodged. 



