BUCCINUM. 313 



odontophore and the muscles. Two otlier prominent 

 vessels (fig. 36) arise at the nerve collar, one on either 

 side of the aorta. They both pass toward the tentacles but 

 before reaching them, small vessels leave dorsally to 

 supply the tissues of the "head" (fig. 36). 



The right tentacular artery gives off at its origin a 

 large branch in the male, the penis artery (fig. 36, 

 A. pen.). 



The Visceral Aorta (figs. 35, 36, A. vis.) can be seen 

 quite distinctly without injecting. It turns abruptly 

 after leaving the ventricle and runs close to the surface 

 across the intestine. Half-way across it gives off a branch 

 (figs. 35, 36, A. g.) on the right side, which passes to the 

 stomach and breaks up into numerous twigs upon its 

 external surface. The main trunk plunges into the mass 

 of the digestive gland, immediately after crossing the 

 intestine, and runs right through, to appear again at the 

 surface on the other side. It now remains at the surface, 

 just below the epithelium, and lying upon the digestive 

 gland a little ventral to the edge of the gonad ; and in 

 this position runs to the end of the visceral mass. 

 Branches are given off at intervals which run out at right 

 angles to supply both the gonad and the digestive gland 

 (fig. 36, A. go.). 



The Venous System. 



The blood which is carried to all parts of the body 

 by the arteries, collects in lacunae and is brought back to 

 certain more extensive central sinuses. Many of the 

 paths which are taken are, however, so narrow and so 

 well-marked that there almost appears to be a definite 

 system of capillaries connecting up the arteries and veins. 

 These channels are mere excavations, which may be lined 



