SEPIA. 281 
The blood vascular system is highly developed. The 
heart lies below the intestine (if the intestine were bent 
Blog. Pack into a straight line it would be in the 
Vascular, Usual dorsal position) and consists of a ventricle 
“and two auricles. The auricles receive blood 
from the ctenidia by the efferent branchials and drive it into 
the ventricle. From the ventricle it passes forwards and 
backwards by anterior and posterior aorta. 
The veins are largely sinuses but are rather more 
definite than in other molluscs. A main vein, the vena 
cava, runs along the mid-ventral line from the head to the 
level of the anus, where it divides into two afferent branchials 
going out to the ctenidia. At the base of the ctenidia each 
afferent branchial swells into a dvanchial heart or contractile 
bulb, which also receives an aédominal vein from the hind 
region and on contraction drives the blood up the ctenidium. 
The heart of the cuttle, like that of our preceding types, is 
therefore systemic, but in addition there is a pair of special 
respiratory or branchial hearts. 
The brain is a large mass lying over the cesophagus and 
protected by the cranial cartilage. It supplies nerves to the 
eyes and the otocysts. Connections run round 
the cesophagus to a ventral nerve-mass which, 
as in the snail, consists of several ganglia. The feda/ and 
pleurovisceral may be distinguished. Nerves from the pedal 
supply the ten tentacles and the siphon. For this and 
other reasons derived from embryology we are led to regard 
the tentacles and the siphon as together representing the foot 
of the other Jo//usca. We have seen that the intestine and 
excretory pores have moved forwards along the mid-ventral 
line and the foot, divided into tentacles, has moved forwards, 
like the appendages of the lobster, to surround the mouth. 
As in the lobster, the ventral surface of the body is bent 
upwards anteriorly. There are two large stellate ganglia 
on the lateral walls of the mantle-cavity, connected by pallial 
nerves to the pleurovisceral ganglia. 
There is a pair of large tubular Azdmeys which open 
internally into the pericardium and externally to the 
exterior as described. They envelop the 
afferent branchial and abdominal veins, and 
their walls consist of thickened excretory cells. 
Nervous, 
Excretory. 
