216 ZOOLOGY 
its chief vessels, the branchial hearts, and in its posterior half 
the genital gland. It is partially divided into two by an in- 
Fia. 127. — Central 
organs of the cir- 
culation, gills, and 
renalorgans of Sepia 
officinalis. After 
John Hunter. 
vv’. Visceral veins. 
a, Aorta. 
v, Vena cava. 
c. Ventricle. 
d. Auricles. 
e. Branchial hearts. 
b. Branchiae. 
r. Renal organs. 
complete septum. It opens into the nephridia by a minute 
pore on each side. 
The heart consists of a ventricle with two auricles opening 
into it. The ventricle is continued in front into an anterior 
aorta, which gives off vessels to the mantle and liver and runs 
forward to the head and arms, and behind into the posterior 
aorta, which supplies the generative organs and the fins, ete. 
The blood passes largely by capillaries but partly by lacunar 
spaces, into the veins. Of these, the largest is the anterior 
vena cava, which has a ventral position and splits into two 
branchial veins. These latter are beset with diverticula of the 
nephridia, and they receive numerous veins which bring back 
the blood from the generative organs, the ink sac, etc. Just 
before they enter the branchial hearts they are joined by veins 
from the mantle and posterior end of the visceral hump. The 
branchial hearts are pulsating muscular enlargements at the 
base of the ctenidia, whose contractions force the blood through 
the gill. A mass of excretory tissue—the pericardial gland— 
