266 NEW YORK STATE MUSEUM 



to the cephalic integument. A branch is also given off, which 

 proceeds alongside the nerve to the muscular collar. Branches 

 also accompany the commissural cord, forming a complete 

 circle. From .this^ on the left side, arteries proceed to the 

 tentacles; from the right side an artery proceeds, which subdi- 

 vides; one branch proceeding to the penis, the other to the vagina; 

 these organs being covered by numerous ramifications. From the 

 artery near the ganglia proceed the arteries supplying the ten- 

 tacles of the right side. 



Veins. The arteries break up into smaller and smaller branches, 

 and finally into a network of capillaries, that meet a similar net- 

 work leading to the veins, which empty into large veins or sinuses; 

 the principal ones of which are three in number. The first begins 

 in the apex of the volutions, receiving the veins from the superior 

 lobe of the digestive gland, continuing on the outer edge of the 

 volution to the beginning of the pulmonary chamber, receiving in 

 its course several large veins. These divide, one division passing 

 along the edge of the pulmonary chamber, alongside the rectum 

 to the thickened muscular collar, passing along the inner edge 

 of this to the base of the pulmonary chamber. The other division 

 passes along the base of the pulmonary chamber, uniting with the 

 first described division at the muscular collar, forming a sinus 

 completely incircling the pulmonary chamber, and known as the 

 circulus venosus pulmonis, or pulmonary circulus. 



The arteries of the foot, as in the visceral part of the body, break 

 up into capillaries, that enter the capillaries of the veins, which 

 empty into a large vein or sinus, situated below the pedal gland. 

 From this sinus proceed numerous veins, which finally connect 

 with the pulmonary circulus. 



From the pulmonary circulus arise many veins, which form a 

 large vein leading to the heart, and known as the pulmonary vein. 

 These veins are known as the efferent veins. They alternate with 

 much regularity with a series of veins leading from the pulmonary 

 vein, but intimately connected with the efferent vessels, which are 

 known as the afferent veins (pi. 11, fig. 1-4). 



Circulation. The circulation is as follows: the blood leaves 



