•276 MR FRANK E. BEDDARD 



tunity of doing this, I do not hesitate to set down the facts that I have been able to 

 gather from an inspection of one individual mounted in Canada balsam, and of a 

 complete series of longitudinal sections of another. 



Previously to receiving, through the kindness of the author, Dr Stolc's beautifully 

 illustrated Memoir upon the Tubificidse of Bohemia [5], I should have been disposed to 

 consider that the presence or absence of a supra-intestinal vessel was characteristic of 

 Claparede's two divisions of the Oligochceta Limicolce and Oligochceta Terricolce. The 

 vessel in question occurs in so many of the former, and had not been noted in the latter. 

 However, Stolc figures such a vessel in his genera Lophochceta and Bothrioneuron [5, 

 pi. ii. figs. 5 and 6]. In both genera it is closely applied to the dorsal oesophageal wall 

 from segment VI.-IX. ; it is furthermore very interesting to note that, as in some Earth- 

 worms, # the supra-intestinal vessel is directly connected with the ventral vessel by hearts 

 (one pair in LophochcBta, two in Bothrioneuron). 



In longitudinal sections of Phreodrilus two perfectly separate vessels may be 

 observed running along the dorsal wall of the oesophagus. Their course is fairly 

 straight, as the worm had been fortunately killed in an extended condition. The two 

 vessels are different from each other in structure, and cannot therefore be confounded 

 in sections, where sometimes only one of the two was visible in a particular segment. 



The vessel, which is closely applied to the dorsal wall of the oesophagus, is extremely 

 thin walled and completely filled with coagulated blood. It resembles in these 

 particulars the ventral blood-vessel. 



The other dorsal vessel, which is separated by some little distance from the supra- 

 intestinal trunk is largely — in some places quite — empty of blood ; it has rather 

 thicker walls, and is of less calibre. This latter fact is probably due to the contraction 

 of the muscular fibres forming the walls of the tube. There is a certain parallelism 

 here to the arteries and veins of the vertebrata. The thick-walled tube less full of blood 

 after death is the artery, and the two thin- walled vessels full of blood are the veins. 

 The thick-walled vessel appears to be the homologue of the dorsal vessel in Earthworms, 

 while the thin wall intimately connected with the dorsal wall of the oesophagus, and 

 giving off branches to it, is clearly the homologue of the supra-intestinal vessel in that 

 group of worms. The dorsal vessel is lined with a layer of cells of some thickness, and 

 its muscular fibres run for the most part in a circular direction. 



I have traced the dorsal vessel from the Vlth segment in front to the XVth segment 

 posteriorly. I am not able to make an accurate statement as to the segment in which 

 it disappears ; but it does not exist for some distance in front of the tail end, as I 

 have been able to prove by transverse sections through some of the posterior segments. 



Another difference which distinguishes the dorsal from the supra-intestinal vessel 

 is the fact that the latter is coated with chloragogen cells ; the peritoneal cells of the 

 dorsal vessel are flattened, and have no yellowish-green granules in their interior. 



* I state the facts with due reservation. It seems to me far from improbable that the " intestinal heart" may 

 ultimately prove to be connected, as they are in Eudrilidse, for example, with both dorsal and supra-intestinal trunk in 

 all worms which possess the latter. 



