200 SUPPLEMENT 
greatest facility. This is most especially evident in the bra- 
chiocephala. 
The liver sometimes appears more considerable in the phy- 
tophagous mollusca than in the zoophagous. 
The intestine, properly so called, varies more than the 
stomach in its diameter, the number and form of its circum- 
volutions, in its direction, and in the point of its termination. 
Most usually its circumvolutions between the lobes of the 
liver, from which it is at times rather difficult to separate them, 
are in the posterior part of the body of the animal. It is dis- 
engaged from them pretty often, proceeding in a middle line 
underneath and in front, or above and behind, but often also 
proceeding from left to right, or in front towards the anterior 
and right side of the animal, where the anus exists. 
The acephala offer perhaps less variations in the extent, the 
circumvolutions, and especially in the mode of termination of 
the intestine; in fact, after having formed a sort of handle, 
more or less large, in the liver, and sometimes a ceecal sinus 
at the root of the foot, it re-ascends towards the back of the 
animal, places itself in the middle line, and directs itself from 
front to rear, where it is terminated in the cavity of the mantle 
by a free elongation, more or less considerable, at the ex- 
tremity of which is the anus. 
The position of the anus in this class of mollusca is thus 
almost constantly the same, and it is pretty generally pedicled. 
The same is not the case with the cephalous mollusca; in 
these the anus, sometimes medial, inferior and anterior, as in 
the brachiocephala, is sometimes medial, posterior, superior 
or inferior, as in doris and peronia. Finally, in most cases it 
is placed at the right, sometimes altogether in front, as in 
limax, or altogether behind, as in onchidia. When it is at 
the left the animal and its shell are so. The haliotides and 
ancile, nevertheless, have it on this side, and are rolled from 
left to right. 
