1U()7.1 



XATUKAL SCIENCES OF I'llILAUELPHIA. 



403 



The lower i>ostcrior end of the ventricle orifrinates the short common 

 aorta, which at its first branch bears a meml)ranous valve. The visceral 

 aorta, arising posteriorly, bends beneath the posterior end of the visceral 

 mass, supplying blood to the stomach, liver, gonad and that portion of 

 the right kidney immediately behind the pericardium. The main artery 

 continues anteriorly, coursing along in the wall of the body just above 

 the epipodium. It soon develops the genital aorta, which proceeds 

 towards the columellar muscle, giving off branches to the alimentary 

 canal, right kidney, liver and gonad. It continues along tlie horn- 



Livet 



/\urtcle-S 

 Fig. B. — Diagram of Haliodft circulation. 



shaped portion of the visceral ma.'^s, branching freely through the liver 

 and gonad. 



The main or buccal aorta bends in a gentle ciu've to the buccal mass, 

 developing, as it courses forward, branches to the viscera. The radula 

 and its sheath lie freely in its lumen (figs. C. D, BAo). and more ante- 

 riorly it originates a branch of moderate size, which, owing to the fact 

 that it supplies the great adductor muscle, may he known as the colu- 

 mellar artery (fig. D, Co). Reaching the head, the buccal aorta in- 

 creases in calil^re to envelop the buccal mass, thus forming the buccal 

 sinus, ^'entrally this sinus passes into the junction of the two pedal 



