GENERAL ANATOMY OF THE SQUID. 345 



5. Lift up the glandular vena cava of one side, and 

 notice, near the point where it unites with its fellow, a 

 glandular branch, which runs downwards into the sub- 

 stance of a white glandular body, the spleen? (Fig. 179, 

 12), which lies below it. 



i. The systemic heart and arteries. 



Remove the branchial heart and venae cavse from the left 

 side of the body, and notice below them, on the median 

 line of the body, the smooth, white systemic heart (Figs. 

 178, k, 179, &), running obliquely across the body, with 

 its anterior end to the left. 



1. Near the middle of its posterior margin, the posterior 

 aorta (Fig. 179, 14), originates, and passes backwards on 

 the median line. 



2. This soon divides into three mantle arteries, already 

 noticed (v, v, v). 



3. Notice the branchial vein (Fig. 179, c, c'), which 

 brings back the blood from the left gill, and opens upon 

 the centre of the rounded left side of the systemic heart. 



4. The right branchial vein opens into the pointed right 

 side of the heart. 



5. On the left side of the body, the anterior end of the 

 heart gives rise to the anterior aorta (Fig. 179, 13), which 

 runs forwards to the left of and below the spleen. Its 

 subsequent course will be traced in connection with the 

 digestive organs. 



IV. The Digestive Organs. 



Remove both veme cavse ; cut the anterior aorta, and 

 remove the systemic heart, and carefully strip oif the del- 

 icate membrane which covers the visceral mass. 



(t. The greater part of this mass is formed by a thin, 

 delicate-walled pouch, the blind sac of the stomach 

 (Figs. 178, ', 180 and 181, k). 



