1912. | E. Guosu: The nervous system of a Snail. 81 
The left visceral commissure is a stout nerve passing back- 
wards along the left side of the dorsum of the foot to the visceral 
ganglion. ‘Two small nerves are sometimes given off from it to 
the floor of the mantle chamber. 
Accessory supra-intestinal ganglion.—This is a small fusiform 
swelling on the left visceral commissure. It is present in many 
specimens but not in all. When present the ganglion gives off 
two nerves, one from each side, to the integument on the dorsum 
of the foot and to the floor of the mantle chamber. These nerves 
are fairly constant, and are present even when the ganglionic 
swelling is not noticed. 
The infra-intestinal commissure passes from the left pleural 
to the right pleural ganglion ; it then leaves the latter and passes 
along the line of union of the integument on the dorsum of the 
foot on the right side, being bridged over by numerous fibrous 
strands throughout the posterior half of its course. The commis- 
sure often presents a ganglionic swelling, sometimes two, between 
the right pleural and the infra-intestinal ganglion. 
Infra-intestinal ganglion.—This is a small ill-developed gang- 
lion lying on the right side beneath the crop. It gives off a small 
nerve to the integument of the right side. The nerve passes out- 
wards to the base of a long fringe-like ridge in the mantle-cavity 
on the right side. It then divides into two branches, which pass 
along the base of the ridge in front and behind. 
Accessory infra-intestinal ganglion.—A small triangular body 
giving off a small nerve to the integument on the dorsum of the 
foot. It lies on the infra-intestinal commissure a little behind the 
infra-intestinal ganglion. 
A still smaller ganglion is sometimes present on the infra- 
intestinal commissure behind the accessory ganglion. 
The right visceral commissure is a fine nerve from the infra- 
intestinal ganglion to the visceral, lying on a thin membrane 
extending from the foot to the base of the visceral hump on the 
right. 
The commissure sometimes presents a small fusiform swelling 
with two nerves from the right side. A small nerve is sometimes 
given off from the right side of the commissure just before it ends 
in the visceral ganglion. 
Visceral or abdominal ganglion.—This is a triangular ganglion 
lying on the right side of the pericardium beneath the integument 
at the base of the visceral hump and behind the posterior end of 
the pulmonary aperture. 
The nerves from the visceral ganglion are :— 
(rt) A small nerve to the heart. 
(2) Astout nerve supplying branches to the stomach, 
intestine, liver, kidney and reproductive organs. 
In conclusion it may be noted that the present species agrees 
with Ampullaria carinata in the general arrangement of the 
