234 
3IESSRS. HANCOCK AND ExHBLETON ON THE ANATOMY OF DORIS. 
taken all together, represent not only the cerebro-spinal system of the Vertebrata, 
but their sympathetic system as well. We are now, however, we hope, prepared to 
show the error of such views, and to supply a desideratum in Comparative Anatomy, 
by pointing out the true sympathetic nervous system of the Mollusca. This system, 
it will be found, bears a very remarkable resemblance to, and correspondence with, 
its counterpart in the Vertebrata ; and whilst its demonstration will, with the other 
new points which we have recorded in this paper, prove the very high degree of 
organization enjoyed by the Nudibranchs, it will also throw a clearer light upon the 
physiology of the whole of the ganglia surrounding the oesophagus than previouslv 
existed. 
The Sympathetic System ^. — This exists, and is more or less demonstrable, in the 
skin, the buccal mass, and in all the internal organs. It consists of a vast number 
of minute distinct ganglia, varying in size and form, the larger quite visible to the 
naked eye, of a bright orange colour like the ganglia round the oesophagus, and 
interconnected by numerous delicate white nervous filaments, arranged in more or 
less open plexuses or networks. This beautiful system is in several points, as already 
indicated, connected with both sets of oesophageal ganglia. 
In the skin the sympathetic system is not very easily detected, nor indeed have 
we much sought for it there ; but we have seen enough to prove its presence in the 
fact of the existence of two or three ganglia in connection with filaments of the 
anterior branches of the branchial ganglion. 
In the buccal mass this system is only a little more evident, and is very difficult 
of investigation ; we have, however, succeeded in making out a few ganglia and nerves 
in the neighbourhood of the oesophagus. First, there is a nerve on the posterior 
surface of the buccal mass passing forward on each side of the infra -oesophageal 
ganglia, and having itself a small ganglion with other nerves at each of its ends im- 
bedded in the buccal mass. This nerve runs within the second collar, communicating 
with it, and giving a twig to the salivary gland ; it also furnishes a twig which joins 
the lingual nerve. This nerve is probably the rudimentary representative of that 
large nerve in Eolis, which passing from the same part of the buccal mass runs also 
within the corresponding collar with which it is in connection, and is distributed to 
the glands of the papillcC. 
Around the oesophagus there is a fine open network -f- of very minute nerves and a 
few ganglia, frequently connected with both of the gastro-oesophageal nerves from the 
infra-oesophageal ganglia. This network at the top sends some offsets to the salivary 
glands, and others to the nerves and ganglia of the buccal mass. The oesophageal 
sympathetic plexus, with the gastro-oesophageal nerves, is continued down as far as 
the cardiac orifice of the stomach ; at this part the gastro-oesophageal or vagi nerves 
pass into two comparatively large ganglia, situate under the cardia; and the oesopha- 
geal plexus, besides giving twigs to these ganglia, is continued into the gastro-hepatic 
* Plate XVII. fig. 1. t Plate XVIII. fig. 3. 
