420 MANUAL OF ZOOLOGY SECT. 



trunk (put. cu. tr}. The carotid and systemic trunks com- 

 municate separately with the bulbus, the two pulmo-cuta- 

 neous trunks communicate with the anterior end of the 

 conus by a single aperture placed just below the free end of 

 the longitudinal valve. 



car.gl n - 



]L r^ 



^^*^^*~ 



car.a.- 

 syst.tr 

 f>ul.cu,.tr'^** 



FlG. 252. Rana temporaria. The heart from the ventral aspect with the cavities 

 laid open, a, a', bristle in left carotid trunk; art. v. v, auriculo-ventricular 

 valves; b,b' ', bristle in left systemic trunk; c, c', bristle in left pulmo-cutaneous 

 trunk; car. a, carotid artery; car. gl, carotid plexus; c. art, conus arteriosus; 

 car. tr, carotid trunk; /. an, left auricle; Ig. a, lingual artery; /. ?', longitudinal 

 valve; finl. cu tr, pulmo-cutaneous trunk; flttl v, aperture of pulmonary veins; 

 r. au, right auricle; .r. an. ap, sinu-auricular aperture; spt. aur, septum auricu- 

 larum; v. v', valves; vt, ventricle. 



After being bound together in the way described for a 

 short distance, the carotid, systemic, and pulmo-cutaneous 

 trunks separate from one another. The carotid trunk divides 



