302 FRANK E. BEDDARD. 
tudinal contractile vascular trunk ; it is only in the esophageal 
region that it is upon the upper surface of the alimentary tract. 
Further back it runs in close contiguity to the ventral blood- 
vessel, so close that at first I was disposed to regard this worm 
as resembling certain Polycheta in having a double ventral 
blood-vessel. It is very easy to see, however, that the two 
trunks do not always run side by side (they do in the branchial 
region), and that one only is contractile. In addition to these 
there is a supra-intestinal vessel, which I was only able to 
recognise in the living worm, upon the cesophagus and just the 
beginning of the intestine, but in sections I traced it further 
back ; it lies beneath the peritoneal covering of the alimentary 
tract, while both the dorsal and ventral vessels lie freely in the 
body-cavity, and the former, like the latter, has no covering of 
pigmented cells. The figure (fig. 10) illustrates the course of 
the principal blood-vessels so far as I was able to make them 
out. Iam not certain about the connection of the dorsal and 
ventral trunks in the most anterior segments. In longitudinal 
sections the close proximity of the dorsal and ventral vessels 
could be easy made out; the latter rests upon the nerve-cord. 
In each segment of the body after the hearts there seem to be 
two peri-intestinal vessels ; one runs in the septum, the other at 
about the level of the setz ; but I did not make out their con- 
nection in a satisfactory way. 
In the section illustrated in fig. 13 the relations of the dorsal 
and ventral vessels in the branchial region of the body and the 
blood-supply of the branchiz can be made out—at least partly. 
The body appears something like the fig. 8 in section, but this 
was not always the case. In those sections which exhibited 
the figure-of-eight outline the upper cavity was exclusively 
occupied by the intestine, the lower cavity by the nervous 
system and the principal blood-vessels. The intestine is attached 
to the parietes by numerous muscular strands, and there 
appears always to be a partitiou! (at sp. in the fig.) which shuts 
the ventral trunk lies towards the dorsal side of the body. In Dero the 
dorsal vessel is ventral in position. 
1 Among the Capitellide and other Polycheta the cclom is similarly 
divided. 
