326 ELEMENTARY BIOLOGY. [CHAP. 



injecting material, into the ventricle. Inject slowly, and dis- 

 sect under water, right side uppermost Remove the gills 

 of the exposed side, together with the hinder three-fourths 

 of the pallial-lobe; leave the labial-palps, but remove the 

 entire body-wall. Work from the ventricle and follow in 

 order — 



a. The anterior aorta; a spacious trunk embracing the 

 rectum dorso-laterally. It runs across the digestive- 

 gland to the right side, distributing branches to it 

 as it does so, and enters the body immediately 

 behind the anterior retractor muscle. Pick away 

 the digestive and reproductive glands, and follow 

 its course; it subdivides into visceral and pedal 

 .branches, asunder. 



a. The visceral artery. Its main branch accom- 

 panies the first coil of the intestine ; it distributes 

 blood to the alimentary and reproductive organs. 



ji. The pedal artery. Follow its further course; its 

 main trunk skirts the upper surface of the foot, 

 and distributes a number of branches to the 

 substance of the same. Soon after leaving the 

 anterior aorta, it gives off a labial branch to the 

 palps, and a pallial one to the anterior adductor 

 muscle and pallial-lobe. 



b. The posterior aorta ; a much shorter trunk than a. 

 It passes beneath the rectum and is mainly distri- 

 buted to the posterior adductor muscle, the pallial 

 lobes and body-wall. 



The two pallial arteries of either side anastomose 

 within the substance of the thickened border of the 

 mantle-lobe. 



