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XXVIII. On the Nervous System of Molluscous Animals. By RonERT Garner, 
Esq., F.L.S. . 
Read November 4th, and December 16th, 1834. 
THOUGH in this paper the author originally included the nervous system 
of the Radiata, yet he now, upon more mature consideration, determines to 
confine his observations to Molluscous animals, convinced that he can add 
little of importance to the recent labours of the German anatomists* in this 
department, who have shown the errors of their predecessors, and themselves 
discovered the true nervous system of Radiated animals. 
In the Tunicata the nervous system consists of a ganglion and nerves 
(Tas. XXIV. fig. 1. A, a, b.), generally very visible on slitting the cartilaginous 
covering. In Phallusia intestinalis, Sav., we discover this single, yellowish 
ganglion, lying upon the muscular coat between its two orifices. In other 
species we see the ganglion nearly divided. One set (a.) of filaments surround 
the branchial orifice, and give nerves to its tentacula, and appear to meet on 
the opposite side, forming in the Phallusia a nerve which seems to run along 
the edge of the elongated branchial fold. "The other set (5.) supply the mus- 
cular tunic, and also the mantle, and go towards the mouth. In Cynthia, 
and those Tunicata, which have thick muscular tunics, the ganglion is not 
visible external to the muscular sac, it being situated in its interior. The 
above-described ganglion is, according to Cuvier, analogous to the posterior: 
or branchial ganglion of Conchifera. In the figure are shown two minute 
bodies (G.) seen on the intestine of PAallusia, which Meckel suspects may be 
ganglia, but which as probably may be traces of a second ovary. 
* More particularly Tiedemann and Ehrenberg. Spix appears to have been mistaken in his ac- 
count of the ganglia and nerves of the Actinia, as he certainly was in that of the nervous system of 
the Asterias. The author's observations agree with those of Leuchart, Rapp, and Meckel in this respect. 
The nerves of Radiata are exceedingly minute and difficult to discover; in preparations the vessels are 
often shown for them. 
