5 SIMPLE TECHNIQUES FOR ANIMALS

A chain of a few little bones transmits sound waves through the Center ear. A muscular diaphragm separates the heart plus the lungs through the abdominal cavity. Only the left aortic arch persists. (In birds the best aortic arch persists; in reptiles, amphibians, and fishes equally arches are retained.) Mature crimson blood cells (erythrocytes) in