THE ANATOMY OF PHORONIS AUSTRALIS. 139 
vessel, but also with a similarly arranged “ recipient vessel ”’ 
(r. v.), which lies somewhat to the outer side of the former, 
though quite close to it. It is very difficult to make out how 
the tentacular vessel communicates with the two spiral 
vessels, but here and there I have observed two tentacular 
vessels in a tentacle (fig. 26). I believe that each tentacular 
vessel divides at its base into two exceedingly short branches, 
one coming from the distributing vessel, the other going into 
the recipient vessel. 
There is a recipient vessel on each side, which follows the 
whole length of the spiral course of the lophophore, then both 
pass alongside the cesophagus through the septum into the 
infraseptal cavity. They remain separate for some distance, 
and lie to the right and left of the cesophagus, but soon the 
right recipient vessel passes round the cesophagus and joins the 
left one to form the efferent trunk (fig. 23). 
This efferent trunk thus lies on the left side of the 
cesophagus.!| As to any anastomosis between the recipient 
and distributing vessels in the lophophore, I am unable to make 
any positive statement. In its course towards the proximal 
end of the body the efferent trunk gives off a number of 
branching czeca, which lie freely in the celom but do not 
reach the body wall, nor unite with the afferent trunk as 
described by Dyster. 
When the trunk reaches the stomach some of these branches 
pass to its wall and form a plexiform sinus around it (fig. 
33, b.s.). In this region, too, these ceca are beset with the 
developing genital cells, in a way to be described later on. 
Having reached nearly to the proximal extremity, the efferent 
trunk bends upon itself and becomes the afferent trunk (fig. 
24). From it are given off ceca near the end of the body, 
some of which form a plexus round the intestine, but as the 
trunk approaches the distal region of the body, no more 
cecal vessels are given off. The wall of the various vessels 
1 McIntosh (19) speaks of a median and a right trunk in a transverse 
section of the body; he must have made some error here, if we accept 
Caldwell’s orientation of the body of Phoronis. 
