THE HEART. 



13 



In the right ventricle the papillary muscles are very different from those in the 

 left. There are three principal muscles. Two arise in the posterior end of the ven- 

 tricle, one running forward along the septum and the other along the outer ventral 



THE CIRCULATORY ORGANS. 



Fig. 2. Heart of seal pnp, natural size. 

 ca. Carotid artery. 

 vert. Vertebral artery. 



th. Thyroid axis. 

 ma. Internal mammary artery. 

 so. Subclavian artery. 

 cLB. Ductus Botalli. 



wall The inner one bifurcates a short distance from its origin, and each arm extends 

 forward a little more than half this length, when it terminates, giving off three chordae. 



