Mr. Garner on the Nervous System of Molluscous Animals. 495 
nected by long nerves to the brain. In Buccinum, the two pharyngeal ganglia 
can be seen to have a root both from the superior and from the inferior portions 
of the brain. The penis in the male receives twigs (r.) from the cerebral por- 
tion near the optic. 
The author need not add his testimony to that of Stiebel, Müller and 
Blainville as to the real dioptrical structure of the eyes of these animals, and 
consequently to their being real visual organs, and not (as has been argued by 
Home) organs of ordinary sensation. No acoustic organ has ever been shown 
to exist, though it appears probable from experiment that there are such, and 
that they might be discovered in large foreign species of Gasteropoda. A 
The author can only refer the reader for the description of the nervous 
system in the Pteropoda and Heteropoda, to the works of Cuvier and Poli; 
but he may observe, that in both these divisions it appears to be scarcely as 
perfect as that of some of the lower Gasteropoda, to which it offers most re- 
semblance, being far below that of the Cephalopoda. 
The nervous system of the Cephalopoda, on one side very similar to that of 
the Gasteropoda, approaches on the other that of some fishes. It may also be 
mentioned that the cartilaginous parts or skeleton offers a greater resemblance 
to the skeleton of a fish than has been supposed. In the Sepia, for instance, 
(excluding the shell of the back from our consideration,) we see a large cere- 
bral cartilage surrounding the brain, supporting the eyes, and presenting a 
number of foramina for the passage of nerves and vessels. There are other 
cartilages dependent upon this, two articulated with each orbital process, and 
another at the base of the anterior feet. There are five lengthened cartilages, 
of which one is anterior to the liver, two lateral, descending from the cartila- 
ginous disk at the back of the neck, and two others, external to the last, at 
the base of the fins. These, according to Cuvier, are a rudiment of a spine. 
In Loligo there is some appearance of this spinal rudiment being articulated ; 
and it may be mentioned that the vertebra of some fishes are more or 
less anchylosed. The structure of the fins offers considerable resemblance 
to that of those organs in cartilaginous fishes, in the skate, for instance. 
The muscular fibres are regularly interspersed by long slender cartilagi- 
nous laminze, arising from a ridge on the longitudinal cartilage. "There are 
other cartilaginous parts, which may be rudiments of shoulder-bones, if 
