50 



cephalic vessel joins the anterior vena cava, a wide vessel 

 running over the ventral wall of the cranial cartilage and 

 the liver, down to the kidneys. At the anterior end of 

 these it bifurcates, and each half runs behind the 

 corresponding kidney and soon meets a vessel running in 

 from the middle region of the venous sinus (fig. 52, 

 Ah, I. V.). These two vessels join to form the Lateral 

 Venn Cava of that side, which slants outwards and down- 

 wards to the branchial heart, behind the kidney (fig. 52, 

 L. V . C). From the antero-external angle of this heart 

 the blood is led by the afferent branchial vessel to the 

 gill, and is distributed to branches which feed each 

 filament, and becoming aerated as it passes through the 

 thin gill laminae, is collected again into the efferent vessel 

 of the gill. The circular cephalic vessel also receives the 

 venous blood from the superficial muscles of the head and 

 neck by means of small branches which run into its 

 aboral wall (fig. 52, Ceph. V. and Sup. V.). The ventral- 

 most of the eight interbrachial vessels appears to run into 

 the cephalic vein sometimes to the right and sometimes 

 to the left of the origin of the anterior vena cava. Some 

 superficial muscles must be dissected away to expose the 

 circular vessel fully. 



Below the origin of the second ventral interbrachial 

 vessel on each side, a large vessel runs in from the 

 surface of the mantle and the eye (tig. 52, M.V.). The 

 origin of this vessel is in the mantle. The whole of the 

 anterior part of the mantle is drained (PI. VII, fig. 57) by 

 a series of vessels of which only (1) is on the internal 

 surface, while (2, 3 and 4) are external. These four 

 vessels unite to form one, which then receives a branch 

 from the postero-dorsal surface of the eyeball, and one 

 from the corresponding lateral wall of the funned 

 (fig. 52, FjFj). Running up the ventral surface of the 



