Circulatory and Respiratory System of a Crayfish
Circulatory and respiratory system of the crayfish. C-heart with three pairs of ostia; Ps, pericardium; Ac, cephalic aorta; A, ab, abdominal aorta; As, sternal artery. The arrows indicate the direction of the flow.
Beach, Fredrick Converse The Encyclopedia Americana (New York, NY: The Americana Company, 1903)