51 



eyeball, just below the skin, this vessel, after receiving 

 small branches on its way, joins the cephalic vessel. The 

 posterior part of the mantle is drained by veins 

 which radiate from a vessel running through the 

 substance of the mantle from its internal surface (figs. 52 

 and 57, M^V^). Here it is joined by the pallial vein, 

 and a vein from the so-called branchial " blood-making 

 gland." The large vessel formed by the union of these 

 three enters the lateral vena cava ventrally just before 

 the latter enters the branchial heart. 



The pallial vein runs ventral to the corresponding 

 pallial artery, down from the stellate ganglion towards 

 the branchial heart. It is formed by the union of an 

 anastomosing network of vessels over the ventral surface 

 of the stellate ganglion, a branch from the great lateral 

 muscle, and several branches from the mantle, and on its 

 course receives several small pallial veins (fig. 52, 

 Pall. V.). 



The Anterior Vena Cava lies on the median ventral 

 surface of the visceral mass and is exposed at the same 

 time as the visceral nerves, by removing the septal muscle 

 and the epithelium covering the visceral mass. It lies 

 to the left of the rectum. lis walls are membranous and 

 semi-transparent. Posteriorly, as mentioned, it ends in 

 two forks which help to form the lateral venae cavae, and 

 anteriorly it originates in a vessel given off from the 

 ventro-posterior wall of the anterior division of the great 

 venous sinus (figs. 52 and 53, >S 1 F 1 ). Soon after its 

 origin it bifurcates, and the two halves run round the 

 origin of the internal funnel protractors, and join again 

 below it (fig. 52). Each of these halves receives a vessel 

 which comes from the venous sinus surrounding the white 

 body, optic ganglion, &c, of the eye, pierces the ventral 

 cranial wall obliquely, and then enters the vena cava (fig. 



