12 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The auricle extends from a point a little behind the middle of the 
pericardium, forward nearly to its anterior boundary where it con- 
stricts and opens into the ventricle. It is a large, loose sack with its 
greatest diameter near the anterior end where sections show it to be 
more than half as wide as the pericardium itself. There is no distinct 
vena cava behind, but the blood would appear to enter the auricle from 
a number of large lacimae in the tissue between the viscera and the 
body wall. 
The ventricle, located in front of the auricle, is small and somewhat 
spherical in form and has thickened walls. The single blood vessel, 
the aorta, arising from the ventricle, passes through the wall of the 
pericardium and extends forward between the vagina and intestine to 
the base of the parapodia where several lacuna-like branches are given 
off. If, as is barely possible, a branch comes from this trunk before it 
reaches the parapodia, I have been unable to find it owing to a certain 
amount of shrinkage and displacement of parts. 
The nephridium is a simple tube shown somewhat diagrammati- 
cally in figure 6 (pi. 2). It has its opening (nephrostome) into the 
pericardial cavity just below and a little behind the ventricle. This 
opening, shown diagrammatically at ?is in figure 6 (pi. 2) is supplied 
with long cilia and surrounded by a muscle. From the nephrostome 
the nephridium runs back nearly to the posterior end of the stomach, 
where it bends around forming a loop after which it takes a forward 
direction so that its middle portion comes to lie close beside and lateral 
to the part at the pericardial end. The anterior third is dilated into a 
loose sack-like structure which opens to the exterior through a pore 
close to the anus. Just back of this anterior enlargement there is a 
more or less noticeable constriction behind which the nephridium again 
slightly enlarges and then tapers unevenly to the small pericardial end. 
Its wall is apparently slightlv glandular throughout. 
Reproductive System. 
The organs connected with generation are divided into two separate 
groups. One of these groups, situated entirely in the body proper, 
consists of the herm;iphroditic gonad, its excurrent duct, the receptacu- 
lum seminis, and two accessory glands. The other group consists of 
the penis and two glands that have their openings in the head. Figure 
6 (pi. 2) shows diagrammatically these parts in their relative positions 
(see also pi. 4, figs. 12, 13, for separate diagrams). 
