VASCULAR SYSTEM OF FROG 



663 



Thus we may distinguish five regions in the heart — the 

 conus arteriosus, the ventricle, the left auricle, the right 

 auricle, and the sinus venosus. The sinus venosus is the 



CU. 



Fig. 381. — Arterial system of frog. 



/., Lingual ; c, carotid ; s., systemic ; cm., cutaneous ; p., pulmonary ; 

 v., occipito-vertebral ; br., bracliial ; cm., coeliaco-mesenteric ; 

 ;'., renal ; il., common iliacs ; //., hsemorrhoiclal. 



hindmost, the conus arteriosus the most anterior part. The 

 opening from the ventricle into the conus is guarded by three 

 semilunar valves, and the cavity of the conus itself is largely 

 filled by a thick longitudinally set spiral ridge projecting 

 from the wall. Other pocket-like valves lie headward of 



