VERTEBRATES I2i 



Heart, lying between the shoulders and in front of the 

 false diaphragm. It is conical in form and composed of 

 three chambers. 



Ventricle, the pink, conical, and muscular portion of the 

 heart, pointing backward and outward. 



Auricles, right and left. These are anterior and dorsal 

 to the ventricle, thin, membranous, and dark-colored. 



Arterial trunk, the single large blood vessel, usually 

 empty of blood, and white. Note its origin and trace it as 

 far as possible, at least until you see it divide to encircle 

 the throat. 



Sinus venosus, a large membranous sac dorsal to the 

 heart and connected with the right auricle. 



Lungs, two small oblong, pink, spongy sacs, lying be- 

 tween and behind the shoulders. 



The pupil may also identify the following structures if a specimen is 

 available which has the blood vessels injected. 



Conus arteriosus, or " arterial trunk," a large artery passing obliquely 

 forward from the ventricle, and dividing into three branches on each side. 



Carotid arteries, the first branches of the conus, to the head and 

 neck. 



Aortas, the second branches of the conus, to the dorsal region. 



Pulmocutaneous arteries, the third branches of the conus, to the lungs 

 and skin. 



Dorsal aorta, the large artery along the back, formed by the union 

 of the two aortas. 



Iliac, or femoral arteries, the two posterior divisions of the dorsal 

 aorta, supplying the legs. 



Posterior (ascending) vena cava, a large vein close to the dorsal 

 aorta, passing forward from the kidneys. 



Hepatic veins, large veins connecting the liver with the posterior 

 vena cava. 



Anterior (descending) venm cava, large veins formed by the junction 

 of the veins from the arm, neck, and head on the right and left sides. 



Subclavian veins, from the arms. 



Jugular veins, from the neck. 



