Mr. Garner on the Nervous System of Molluscous Animals. 489 
ferent position, but where one might expect to find them, at the base of the 
branchize on the back. Perhaps we might infer from Cuvier’s description that 
the nervous system in Haliotis is similarly disposed. In Lottia, which has 
a single branchial appendage over the neck, and a branchial circle besides 
around the mantle, the ganglia are unaltered in their position. Besides eyes, 
we have in Gasteropoda another important part more than we find in Conchi- 
fera, the pharynx or manducatory apparatus at the commencement of the ceso- 
phagus, consisting of a muscular cavity, with a curious spiniferous tongue at 
its floor, often supported by two or more cartilages, and sometimes furnished 
with one or two horny maxillae. Either a transverse band or two ganglia 
supply this complicated apparatus with nerves, this band, or these ganglia 
being always suboesophageal, forming another ring around the digestive 
canal. In Patella this band (D.) is connected with two ganglia (E.), which 
supply the fleshy lip of the animal, and not with the cerebral ganglia. 
Thus the second part of the digestive canal has its ganglion connected with 
those supplying the nerves of the entrance, and through them with the brain ; 
the functions of the parts appearing thus naturally combined. The Patella 
appears to be the only Gasteropodous animal where these labial ganglia exist 
separate from the superior or cerebral ganglia. In the Cephalopoda, however, 
there are distinct labial and pharyngeal ganglia, the latter, as in Patella, only 
connected to the superior ganglion through the former. These pharyngeal 
ganglia, besides supplying the pharynx, give origin to superior visceral or sym- 
pathetic nerves (k, l), very fine and delicate, ascending and descending on 
the cesophagus and getting upon the salivary ducts and glands. 
In Chiton (fig. 1. & 2.), there being no eyes nor tentacles, the upper portion 
of the ring has no evident ganglia. The branchial (C.) and pedal ganglia (B.) 
are sometimes distinct, sometimes conjoined on the inferior portion of the 
ring. The pharyngeal ganglia are also developed on the ring. 
In Scyllea (fig. 4.), an animal not covered, like Patella and Chiton, with 
hard, insensible, testaceous parts, but with a delicate and sensible dorsal 
integument, bearing also the branchiz (the muscular foot having almost 
disappeared), we find the brain entirely supracesophageal from the change 
above mentioned. It appears composed of four united ganglia (A.), probably 
the cerebral and branchial, which latter might be appropriately named 
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