XV 



THE CIRCULATORY SYSTEM 



265 



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

 \.\\Q precavai veins, or anteiior vence cavce, enter; the poste- 



'.ar.gl 



cana. 



syst.tr — %^!^^^^^^^ 

 pal.cw.tr 



C.ourt 



ctu^.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 pulmo-cutaneous trunk; car.a, carotid artery; car.gl, 

 carotid gland ; cart, bulbus 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 veins ; r.au, right auricle ; s.au.ap, sinu-auricular 

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

 (From Parker and Hasvvell's Zoology.) 



rior apex receives the large postcaval \€m, or posterior vena 

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

 pulmonary vein, which empties into the left auricle. 



