In rabbits (and in all mammals), the left auricle (or left atrium) is the chamber of the heart that receives oxygenated blood from the lungs via the pulmonary veins. 

Pulmonary Circulation:The lungs are part of the pulmonary circuit, where blood travels from the heart to the lungs to pick up oxygen and then returns to the heart. The pulmonary veins deliver this oxygenated blood to the left atrium, which is the upper chamber on the left side of the heart.