Circulation of a Fish
A diagram of the circulation of a fish. Labels: 1, The pericardium. 2, The single auricle. 3, The single ventricle. 4, The vessel that conveys the blood from the ventricle to the gills. 5, The vessel that conveys the blood from the body to the heart. The arrows show the direction of the blood.
Cutter, Calvin First Book on Analytic Anatomy, Physiology and Hygiene, Human and Comparative (Philadelphia: J. B. Lippincott & Co., 1875) 128