A frog has two auricles and one ventricle in its heart; meaning it has a three-chambered heart in total. Auricles are the upper chambers of the heart, while the ventricle is the lower chamber. Since frogs are amphibians, their hearts typically have two atria and one ventricle. 

In summary, a  frog's heart:

• Three chambers: Two auricles and one ventricle 
• Incomplete double circulation: Due to the single ventricle, oxygenated and deoxygenated blood can mix slightly 
• Amphibian characteristic: All amphibians have a three-chambered heart