49 



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 Eledone, 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 

 the arm (PI. VII, fig. 54, Arm V x , Arm V 2 , and 

 fig. 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 join 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 

 arms down to the level of the anterior border of the head 

 (fig. 52, Br. V.). <)n the way they receive numerous 

 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 f]\e eyes. Ventrally this 

 r> 



