416 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
From the inner sides of the cerebro-pleural ganglia 
two delicate nerves (fig. 27, V. ot.) arise which pass deeper 
into the tissue and innervate two small bodies, which have 
a white appearance in dissections. 
These are the otocysts (fig. 27, Ot.), and the Otocystie 
nerves in Pecten can thus be traced directly from the 
Cerebro-pleural ganglia. The lower ends of the cerebro- 
pleural ganglia gradually pass into the cerebro-visceral 
connectives (fig. 26, Con. c.). 
The Cerebro-pedal Connectives are very short nerves 
(fig. 27, Con. cp.), which arise about the middle of the 
inner sides of the cerebro-pleural ganglia and run towards 
each other and slightly towards the surface. They each 
hear a ganglionic swelling just before arriving at the 
pedal gangha. 
The Pedal Ganglia (G.p.) lie closely apposed to 
one another, so thai the pedal commissure is so short that 
it is barely distinguishable. These gangha are situated 
outside the foot, and are the nearest to the surface, so that 
probably they will be the first seen when looking for the 
cerebro-pleural. Both the cerebral and the pedal ganglia 
are pigmented yellow, and both have a similar structure, 
viz., a cortex of ganglion cells with processes passing into 
a core, made up of nerve fibres. 
From the pedal ganglia, two pedal nerves (fig. 27, 
NV. .) pass directly into the foot, where they break up 
into numerous small branches, supplying the muscles. 
The Visceral or Parieto-splanchnic ganglia are 
completely fused in Pecten to form one large and com- 
plicated mass (figs. 26, 28, G.sp.). It is the largest 
ganglion and gives rise to most of the nerves, and this can 
be accounted for by the fact that, compared with other 
Lamellibranchs, it is the posterior region of the body that 
is most developed in Pecten, the anterior with the anterior 
