XV 



THE CIRCULATORY SYSTEM 



265 



walled simis venosus ; at the two anterior angles of the sinus 

 XhQ precaval veins, or anterior vence cava, enter; the poste- 



aeir.gl 



car.a. 



aw.v.v 



Fig. 72. — The heart of a frog cut open and seen from the ventral side, 

 a, a', bristle passed into the left carotid trunk ; au.v.v, auriculo^ven- 

 tricular valves; b,b', bristle passed into the left systemic trunk; c,c' , 

 bristle in left puhno-cutaneous trunk; car.a, carotid artery; car.gl, 

 carotid gland ; cart, bulbu^ cordis (conus arteriosus of some authors) ; 

 car.tr, carotid trunk; l.au, left auricle; Ig.a, lingual artery; l.v, longi- 

 tudinal or spiral valve ; pul.cu.tr, pulmo-cutaneous trunk; pul.v, open-' 

 ing of pulmonary vtins; r.au, right auricle; s.au.ap, sinu-auricular 

 aperture; spt.aur, inter-auricular septum; v,v', valves; vt, ventricle. 

 (From Parker and Haswell's Zoology.) ^ "' 



rior apex receives the large postcaval vein, or posterior vena 

 cava. In front of the anterior margin of the sinus is the 

 pubnonary vein, which empties into the left auricle. 



