. 
Mr. Garner on the Nervous System of Molluscous Animals. 493 
in this little animal eleven ganglia. The genus Trochus appears similar in 
its nervous system, as does Cyclostoma*. 
In Neritina (fig. 10 & 11.) we find the two branchial and pedal ganglia of 
Patella become quite united into a transverse oval mass (O.), which, there- . 
fore, as well as the foot, also supplies the nerves we have just seen going from 
the superior compound ganglia. The two connecting filaments remain di- 
stinct as they were in Patella. ! 
The Planorbis (Tas. XXVI. fig. 7 &8.) has a nervous system rather remark- 
able, as the animal itself is in other respects, being organized to respire both 
air and water. There is a branchial cavity with a wide anterior opening as 
usual, containing a long branchial appendage; a small opening leads out of 
this cavity into the pulmonary cavity. Near this opening is the rudiment 
of the other branchial appendage. Two filaments connect the separate 
lateral superior ganglia (A.) with the inferior part of the ring, where the four 
ganglia with their connecting nerves form a quadrangle. The branchial 
cavity would appear to be supplied from the two posterior ganglia of these. 
A filament from the right side mounts over the cesophagus, joining one from 
the left, and together they form a ganglion supplying the pulmonary cavity 
situated to the left. Some filaments (e.) likewise from the posterior part 
of the quadrangle and from the ganglion just described, supply the shell- 
muscles, and form a small ganglion (G.), supplying the branchial appendage 
and viscera. 
In Carocolla (TAB. XXV. fig. 12.), Helix, Limax, Partula, Achatina, and 
Bulimus (fig. 13.) the author finds little difference in the form of the nervous 
system. The brain when cut across over the cesophagus appears of a diamond 
form, a branch of the aorta dividing the anterior pedal portion below from the 
posterior part. From the anterior part below arise the numerous nerves of 
the foot (d.), others for the shell-muscles, and a few (p.) for the flanks of the 
animal: from the posterior portion in the centre proceed the visceral nerves 
(f), often forming a sympathetic ganglion (G.) on the stomach, and some- 
times another in the right side, which appears rather to belong to the genera- 
tive organs than to the mantle: the posterior portion also gives origin, a little 
without the last, to the nerves-of the mantle, which here do not cross. The 
* Berkeley, Zool. Journ. 
