494 Mr. Garner on the Nervous System of Molluscous Animals. 



pharynget-xl ganglia (D.) send down distinct filaments to the salivary ducts and 

 towards the ganglion on the stomach ; the retractor muscles of the pha- 

 rynx being supplied with nerves {g.) from a point close to tliose which arise 

 to form them (in these animals midway between the superior and inferior 

 portions). We shall see in Cephalopoda that the pharyngeal ganglia through 

 the labial receive a filament both from the superior and inferior portions of 

 the ring ; and in Gasteropoda it may often also be noticed that a filament 

 runs back from the labial nerves (?'.) to the nerve forming the pharyngeal 

 ganglia. The nerves of the eye, tentacles and lips are given off, as usual, on 

 each side superiorly, the part whei'e they arise being sometimes more or less 

 swollen into a ganglion on the ring. 



In Natlca (Tab. XXVI. fig. 6.), Bucchmm (fig. I, 2 &3.), Purpura (fig. 10.), 

 Murex, MHra (fig. 1 ) .), Columbella* (fig. 12.), and Oliva (fig. 4 & .5.), all spiral, 

 branchiferous, and carnivorous Gasteropoda, the nervous system is very similar 

 in all. The brain is still principally suboesophageal, and it presents much 

 resemblance to that of the Sepia. From the posterior part the branchio- 

 visceral nerves (f.) arise, generally forming a ganglion or plexus (g.) at the 

 back of the thoracic cavity, near the second stomach. The right nerve of the 

 mantle (c.) crosses over the oesophagus, a ganglion (H.) being formed on it, 

 near the brain, in Buccinum and Purpura. This nerve, and its fellow, which 

 does not cross under the oesophagus, supply the margin of the branchial 

 cavity and sipiion. In Natica tlie right goes to the left over the oesophagus, 

 and the left under it to the right, both forming a ganglion (H.). From the 

 anterior part of the inferior portion the nerves of the foot (</.) are derived ; also 

 in part those of the retractor muscle of the animal into its shell : a few fila- 

 ments (/(.) arise on each side this part to the sides and integument of the 

 neck. The nerves of the lips (/.), eyes, and tentacles {g.) arise as usual ; the 

 former in part siipply the muscles of the proboscis, the other nerves supply- 

 ing the oi'gan more anteriorly, being from the pharyngeal nerve. The pharyn- 

 geal ganglia (D.) in Purpura and Buccinum are close to the brain, the nerves 

 proceeding from them being very long, to allow of the extension of the pro- 

 boscis ; in Xatica they are situated as usual on the pharynx, and are con- 



* The author takes the liberty of introducing figures of Mitra and Columbella, though not bearing 

 upon the subject of the paper, because he believes the animals have not been described. 



