1912.] E. GHosu: The nervous system of a Snail. 79 
(7) Several small nerves from the inner aspect of the 
lower border of the cerebral ganglion. Some of 
these supply the small muscular strands from the 
integument to the buccal bulb, while others end 
in the ventral wall of the head. 
Both the cerebral ganglia give off nerves having similar dis- 
tribution. 
Buccal ganglion.—Kach ganglion is triangular in shape, and 
is placed at the junction of the oesophagus with the buccal bulb 
towards the ventral aspect. Each is connected to the cerebral 
ganglion of the same side by means of a fine nerve. It supplies 
nerves to the buccal bulb, salivary glands and the crop. 
The nerves from the buccal ganglion are :— 
(rt) A fine nerve from the anterior angle anastomosing 
with that from the ganglion of the other side. 
It gives off, a little beyond its origin, a small 
branch which divides into two branches again 
supplying the ventral wall of the buccal bulb. 
(2) A nerve from the outer angle running up to the 
dorsal surface of the buccal bulb ; it communicates 
with the cerebral ganglion of the same side by a 
fine commissure. 
(3) A nerve from the posterior angle which passes back- 
wards to supply the salivary gland of the same 
side and the crop. 
The cerebro-pleural and cerebro-pedal commissures are long, 
thick, flattened commissures passing downwards and backwards 
from the cerebral to the pleural and pedal ganglion of the same 
side respectively. They are placed on the side of the buccal bulb. 
Left pleural ganglion.—It is placed in close connection with 
the pedal of the same side so that the pleuro-pedal commissure is 
practically absent. It is also connected to the supra-intestinal 
ganglion by a thick secondary connective, and to the opposite 
pleural ganglion by a portion of the infra-intestinal nerve which 
passes through the latter in its course to the infra-intestinal 
ganglion. 
The nerves from the left pleural ganglion are :— 
(1) The left pallial nerve which lies at first in the same 
sheath with the secondary connective between the 
left pleural and the supra-intestinal ganglion. It 
then leaves the latter and passes up to the ventral 
aspect of the mantle flap just behind the thick 
margin lying in a canal throughout its course. It 
supplies the mantle and the osphradium. The 
position of the nerve is marked by a translucent 
line on the dorsum of the foot. 
(2) A small nerve to the left siphon flap. 
