No. 419.] A PARASITIC OLIGOCH.ETE. 907 
in side view appears obliquely truncate. The mouth leads 
directly into the pharynx, which occupies rather more than one- 
third the length of the animal, is extremely distensible, and is 
connected by muscle bundles to the body wall. The pharynx 
is succeeded by an cesophagus so short and narrow as to be, 
when the other parts are greatly dilated, quite indistinguishable. 
Next comes the stomach, which as seen in optical section is 
nearly square and is separated by a constriction from the 
intestine, This division is somewhat longer than broad, and 
its walls are usually characterized by a yellowish brown hue, 
sometimes to be observed also on the stomach and suggest- 
ing the chloragogue cells of Lumbricus. Opposite the third 
abdominal setze is a constriction, at which point this yellow 
Color suddenly disappears. The remaining part of the intes- 
tine varies in shape according to the degree of development of 
the buds. The hind end of the worm is slightly notched. 
The stomach is often found filled with diatoms, with which 
are likely to be intermingled a few pebbles. The other parts 
of the alimentary tract, if not entirely empty, are usually 
nearly SO. 
There are five septa: one opposite the anterior and one 
Opposite the posterior end of the cesophagus; one at the 
constriction between stomach and intestine, one opposite the 
middle of the intestine, and one at the point of its posterior 
constriction, Behind the fourth abdominal seta is a zone in 
Which the coelom may be absent, and behind this region may 
appear the ccelom of the bud. 
The large blood trunks are a dorsal pulsatile and a ventral 
nonpulsatile one. They are connected by a pair of pulsatile 
Vessels which encircle the cesophagus. Lankester has figured 
a pair óf anterior ones extending obliquely down and back 
around the pharynx; I have seen such vessels, but am not 
Sure of the way in which they connect (as they undoubtedly do) 
With the longitudinal ones. The blood is colorless. 
Of Segmental organs I have observed only three pairs ; they 
Appear as coiled granular organs in the last three segments. I 
have not found them in the segment which corresponds to the 
anterior abdominal setze. 
