The functionally two-chambered heart is of interest on account of both its rarity and the unexpected duration of life in an occasional case. Textbooks often dismiss the subject with few words as one incompatible with life. Abbott,1 however, cited two cases (Peacock and Young) of "cor biloculare" in which death occurred at the end of the fourth decade with only terminal symptoms, and two (Mann and Holmes) in which the subjects attained 21 and 24 years, respectively. Lineback2 described the heart of a new-born infant in which incompletely separated atriums opened through a bicuspid valve into a single ventricle; torsion was incomplete. "Fischer3 in 1912, reported the case of a man, aged 21, who died of renal abscess following angina. At necropsy the heart was found to be quite similar to the present (Lineback's) case, having only one ventricle discharging blood into an aorta and a pulmonary