16 Observations upon the Habits, Structure and [January, — 
draw the substance back again immediately into the mouth, and 
at times, after all this labor to get rid of a substance, it finally 
succeeds in eluding the tentacles, which flag in their activity after 
a few efforts, and passes on down the canal. From the tower 
anterior portion of the stomach there is given off a long, fadet 7 
saccular diverticulum which extends forward along the lower — 
portion of the right side of the pharynx to about the middle of this — 
part of the body, where it is attached by one or two bands to the 
bars of the branchial arches, and perhaps to the side muscles, 
Fig. 3, Pl. 1. This organ is considered to represent the liver. It ; 
is of a dark-green or brown color, which is probably due to pig- — 
ment cells in its walls. The walls of the stomach are also 
colored, but not so deeply as those of this saccular liver, All — 
this portion of the alimentary canal, including the pharynx, cesoph- — 2 
agus and stomach, is covered with a delicate membrane which 4 
is reflected from the inside of the abdominal walls, and forms | 
along the roof of the branchium, on either side of the canal, 
a true pleuro-peritoneal cavity, or schizoccele, which extends 
back quite to the end of the digestive tract. The intestine 
forms the posterior portion of the alimentary canal, and passes — | 
in a perfectly direct course from the stomach to the hind end — 
of the body. It is much smaller than any other portion of 
the canal, and is of uniform diameter except at the posterior 
extremity where it enlarges to form the funnel-shaped outlet of 
the anus. It is not known at present time whether the cilia 
along the course of the alimentary canal are continuously at work 
drawing in food, or whether they have periods of rest during 
which they are perfectly quiet. I have never seen them quiet 
except upon small patches and in weak animals, and thea not for 
any great length of time, but the fact that the stomach and intes- 
tine are very frequently found devoid of food, or of all but a small 
are not always feeding, and this would imply that they can con- 
trol, in some manner, the action of the cilia. This would accord 
well with their habits, and would corroborate to a certain extent 
the statement already made, that they probably have feeding 
periods, during which they appear at or near the surface, and rest- 
ing spells, when they hide from sight. : 
[To be concluded. | 
