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"Diagrams of the structure of the heart in the lower Vertebrates. A, primitive condition; B, the position of the parts in the fishes. a, artery; au., auricle; c, conus arteriosus with valves; s.v., sinus venosus; v, valves; ve., vein; vent., ventricle. The dorsal portion of the heart is toward the bottom of the figure." -Galloway, 1915

Vertebrate Heart

"Diagrams of the structure of the heart in the lower Vertebrates. A, primitive condition; B, the position…