ELEDONE. 517 
ventricle. It runs posteriorly to the genital gland, and 
ends in several ramifying branches to this organ (fig. 
42, G.A.). 
VENOUS SYSTEM. 
The blood which has been carried to all parts of the 
body by the arteries, ultimately passes from the 
arterial to the venous capillaries, and then flows into a 
system of veins with definite walls, which carry the 
de-oxygenated blood back to the gills for aeration. Hence 
in Hledone, as in most Cephalopods, the circulatory 
system is highly organised. But still there is one large 
venous sinus through which blood flows on its return to 
the gills. 
The blood from the arms is collected into two rather 
wide, superficial vessels, which run one on each side of 
emarme(rl! Vil, fig. 04, Arm V,, Arm V,, and 
fio, 52). These lateral veins, externally or aborally 
receive branches from the aboral part of the arm, and 
from the web. Orally they receive a series of vessels 
which alternate with the suckers (Pl. VII, fig. 58). All 
these veins are superficial. The alternating vessels of 
one side of the arm anastomose at their origin with those 
of the other side of that arm (fig. 58). Towards the 
bases of the arms, these brachial veins joi in pairs 
(figs. 52 and 54), each pair being formed by the neigh- 
_bouring veins of any two successive arms. Thus eight 
vessels are formed, which run in the grooves between the 
4 arms down to the level of the anterior border of the head 
(fig. 52, Br. V.). On the way they receive numerous 
g branches from the surface of the arms and the web. ‘The 
posterior ends of these eight vessels are united by a 
circular vessel of similar width, which embraces the head 
superficially, just anterior to the eyes. Ventrally this 
LL 
