70 



The main branch contimies (h)wnwaT(l, still situated 

 slightly nearer the right side of the animal, to enter the 

 visceral mass, and branches are given o^ to the digestive 

 ffland. On the right side of the aorta a vessel arises which 

 reaches the surface in the median line above the base of 

 the foot, along the upper side of which it passes just 

 beneath the epidermis, to supply the foot with blood 

 (fig. IT, A. p.). This vessel gives off branches to the 

 loAver lip and inner palps, as indicated in the figure. 



Returning' to the main branch, this is continued bv a 

 smaller vessel which lies on the right side of the 

 alimentary canal, and follows it in its course through the 

 visceral mass, giving off small vessels to the ascending 

 loop of the intestine and to the reproductive organs. 

 There is another vessel of almost the same size which 

 arises from the above, at about the level of the foot, and 

 passing deeper into the visceral mass, bifurcates into two 

 branches which pass along the left side of the descending 

 loop of the intestine (fig. 14, A. v.). 



The Posterior Aorta (fig. 14, Ao. p.) is a large vessel 

 which leaves the ventricle below the intestine and on its 

 right side. It runs for a short distance along the right 

 ventro-lateral side of the rectum, and then gives rise to 

 three vessels, the Eectal Artery (fig. 14, .4. r.), which runs 

 alongside the rectum, supplying it to the end, and two 

 much larger A^essels. One is the Posterior Pallial Artery 

 (fig. 14, ^4. p. p).), the most important artery to the 

 mantle, which turns upwards at an acute angle and runs 

 in the roof of the pericardium towards the hinge line ; it 

 then passes to the posterior angle of the hinge and 

 bifurcates, forming right and left Circumpallial (fig. 14, 

 .4. c.) arteries, Avhich pass round the extreme margin of 

 the mantle lobes and communicate eventually with the 

 much smaller anterior pallial arteries. 



