A MOLLUSCA. 
salivary glands (b). The brain-ring (e) has on 
each side a large three-lobed ganglion (f), whence 
numerous nerves pass to the surrounding parts, 
; and two long branches 
| (h) extend backwards 
along the sides of the 
abdomen, to two gan- 
aha (7,2), placed above 
the muscular foot. 
Behind these are two 
sympathetic ganglia, 
(k,k), which send 
threads to the diges- 
tive system, the ovary 
(0), the oviduct (p), 
the uterine sac (q), the 
vulva (m),and the uri- 
nary organs (n). This 
may be considered as 
fa fair average sample 
| of the nervous system 
fin the Mo.uusca, 
being selected from 
Ba Class presenting 
ineither the highest, 
B nor the lowest forms 
| of organization. 
The nervous centres 
are, for the most part, 
grouped without regard to symmetry, those of one 
side not corresponding to those of the other; and 
this irregularity is characteristic of the whole Di- 
vision, not only in the nerves, but in the other 
organs of the body. Some zoologists have derived 
from this peculiarity, a name for the Division, suf- 
NERVES OF BULLA. 
