GENERAL ANATOMY OF THE SQUID. 343 



vena cava (Fig. 178,^), which is flattened, and nearly as 

 wide as long. 



c. Notice that the cavity of the renal organ (Fig. 

 178, ^), extends backward only as far as the posterior 

 end of this structure. 



d. Following the posterior vena cava backwards, it will 

 be found to be a thin-walled tube (Fig. 178, q), capable 

 of great distension, and usually filled with coagulated 

 blood. It runs back around the bod}^ into the mantle. 



e. Carefully dissect away the membrane which covers 

 it, and notice close beside it the dorsal mantle artery 

 (Fig. 178, r). 



f. Opposite and outside of the point where the anterior 

 and posterior venoe cavje meet, notice the branchial heart 

 (Fig. 178, o), in a separate pericardial chamber. 



rj. Open this chamber and turn the heart over, and 

 notice that the two vense cavge open into it, and that a- 

 large vessel, the branchial artery (Fig. 178, Z), passes 

 from it to the gill (6). 



Trace this vessel out alongr the line where the m\\ is 

 joined to the mantle, and notice that it gives rise, at right 

 angles, to a series of small vessels, which pass into the 

 gill leaflets, and there give rise to still smaller branches. 



h. Dissect away the connective tissue which binds the 

 ink bag and rectum to the surface of the body, until these 

 organs cail l)e turned to one side, as shown in Fig. 179, 

 at d and 7<, to expose the structures below them. 



1. Xotice that the anterior vena cava of the left side 

 gives off" a small glandular branch to the intestine. 



2. The two venge cavae (Fig. 179, «, z*), then pass below 

 the intestine, and unite to form a large flat glandular body, 

 which lies upon the median line, and is contained in a pro- 

 longation of the renal organs. 



