[157] CEPHALOPODA OF NORTHEASTERN COAST OF AMERICA. 367 



anterior end of a thin, median, membranous partition, .supplies the ven- 

 tral and lateral portions of the mantle, sending branches both 1 jack- 

 ward and forward; the other two main divisions (<>', o") diverge as they 

 go backward, and supply the caudal fins and adjacent parts of the 

 mantle. The anterior aorta (ao) arises from the right anterior corner of 

 the heart, and goes forward to the head, on the right side of the 

 median line, by the side of the oesophagus. Just beyond the constric- 

 tion, at its origin, it is somewhat bulbous. A short distance from its 

 origin it gives off a large branch, the gastric artery (so), which sends a 

 branch to the renal organs, and passes backward over the dorsal side of 

 the heart to the anterior parts of the stomach, where it ramifies exten- 

 sively. 



The portion of the aorta which passes along and through the liver 

 gives off several hepatic arteries that supply blood to the liver, and one 

 branch emerges from the liver, on the dorsal side, and supplies the 

 muscles of the neck-region. The ultimate divisions of the aorta supply 

 the various organs of the head, and a large branch goes out to the tip 

 of each arm, nearly in the center, sending branches to the suckers. A 

 small vessel, the spermatic artery (fig. 2, go), arises from the anterior 

 side of the heart, and, passing backward over the heart, supplies the 

 spermary (t). 



The large efferent or branchio-cardiac vessels from the gills (bo) 

 enter the anterior lateral corners of the heart, their dilated basal por- 

 tion serving, apparently, as auricles. The branchial auricles (au), situ- 

 ated just behind the bases of the gills, are nearly globular, with a 

 small, rounded, whitish elevation on the free posterior end; anteriorly 

 they receive the blood from the sacculated divisions of the anterior 

 and posterior venae-cavre, above the heart, and from the veins (v, vc') 

 coining from the lateral portions of the mantle, behind the gills, and 

 they give off the large afferent vessels (bv), which go to and run along 

 the dorsal side of the gills. The anterior vena-cava (vc) receives the 

 venous, blood from a large cephalic venous sinus * whieh surrounds the 

 pharynx, at the bases of the arms, and is also directly connected with 

 another large sinus at the back of each eye-orbit. This cephalic sinus 

 receives the blood from a large vein in the median line and near the 

 inner face of each arm. The ophthalmic sinuses receive veins from the 

 eye itself. Numerous small veins enter the anterior vena-cava, from 

 each side, along its course, coming. from the muscles of the head, neck, 

 and siphon, and from the ink-sac, liver, &c. Two veins, sacculated 

 posteriorly, go from the ink-sac and intestine back to the renal organs. 

 A small but very distinct vein extends along the dorsal side of the 

 efferent sperm-duct (p). Two large pallial veins, on each side, come 



* The greater part of the venous system can he easily injected by inserting The 

 cauula into this sinus, through the folds of the buccal membranes, just between the 

 bases' of the arms and the jaws, or between the outer and inner buccal membranes. 

 It can also be easily injected through the vena-cava in the lower side of the head. 



