606 
lia. appear to be liar to Patella, 
ut are found more dintiantly developed in the 
Cephalopoda. 
Fig. 340 is a repre- 
Fig. 340. sentation of the nervous 
i system of Chiton Mar- 
moratus from the dissec- 
tion of Mr. Garner, in 
which the annular form 
of the nervous system is 
very perfect. The animal 
D presents many points of 
resemblance to Patella, 
and there is essentially 
the same arrangement of 
Jj its nervous system. The 
absence of ganglia on the 
/ upper of the ring (i) 
is attributed by Mr. Gar- 
ner to the want of eyes 
and of Ewen 
: Chit In Aplysia there is 
= aly an pin * cerebral 
. al lion. ganglion resulting from 
©, bedachial S agiienk the function of two 
D ? pharyngeal lion.above the cso s 
Toad Ving (cotebral gan. (°? 6° 241)> frome which 
glion.) small nerves pass to 
form the pharyngeal gan- 
glion (p) beneath the pharynx: from this two 
nerves pass backwards to form the pedal gan- 
glion, which also gives nerves to supply the 
mantle (P), and in the posterior part of the 
body there is an additional ganglion, the 
branchial (B, fig. 341). 
Fig. 341. 
Nervous system of Aplysia. 
In Scyllea, according to Mr. Garner, the 
brain is entirely supra-cesophageal ; it appears 
to be com of four united ganglia, pro- 
bably the cerebral and branchial. The foot has 
become too insignificant to require appropriate 
glia. Mr.Garner has noticed two minute 
black spots, one on each side of the brain, 
composed probably of black pigment, which 
he considers to be rudimentary of eyes. 
NERVOUS SYSTEM. (Comparative Anatomy.) 
Fig. 342. 
Nervous system of Scyll@a Pelagica. 3 
A, cerebral ganglion, D, pharyngeal gangli 
ce, d, i, visceral branches, ae 
In Limar ater oeons: slug) the ners 
system is apparently much more si Bu 
FA a little ecauiastinn it will be Pos i e 
sist of the same essential A large s 
cesophageal ganglion, bilobed, constitr es 
brain (a, fig. 343), from each side of which a 
of nerves passes downwards to join a large s 
esophageal ganglion, - 343. 
which supplies nerves si 
to the respiratory sac «a J 
and to the foot or loco- Ra 4 
wm 
motive a’ tus. And 
the sharenaial ganglia 
are, as in Patella, con- 
nected with theanterior 
ganglion. In the sub- 
esophageal ganglion 
we see, conjoined, the 
pedal and branchial 
ganglia. 
In Buccinum unda- 
tum the principal ner- 
vous mass is sub-ceso- 
phageal, and from it 
nerves pass to the bran- 
chie and viscera, and 
also to the foot and 
integument. The for- 
mer nerves form a gan- 
glion, which may be 
7 
regarded as the bran- Nowe a i 
chial ganglion. ]* ater) aq 
For the nervous sys- 4, supra - esc : 
tems of Pteropoda and ganglion d 
Capeaiahom, == phageal lion 
articles under those terior ony 
titles. ganglions, = 
Arricutata.—In taking a general : 
of the structure of the articulated animals 
observe that their body is divided into a ce 
definite number of segments, each one of ¥ 
’ ae 
* See Garner’s paper, loc. cit. As oa 
