Section of Vertebrate
Diagrammatic sections of the ideal vertebrate. A, sagittal section showing the brain and spinal cord on the dorsal side of the notochord, and the alimentary canal and viscera on the ventral side of it. B, transverse section of the head, showing a gill arch and filaments of the left and a gill cleft on the right. C, transverse section of the trunk, showing the gut, the genital glands, and the excretory organs in the body cavity. D, transverse section of the tail.
Beach, Fredrick Converse The Encyclopedia Americana (New York, NY: The Americana Company, 1903)