Note the large powerful _pectoral muscles_. Note a hard median projection of bone, the _sternum_, which is a large keel-shaped bone with lateral expansions to which are attached the _ribs_. Where are the largest and most powerful muscles of the toad located? Where are they in the fish? In the bird the most powerful muscles are these pectoral muscles, which move the wings in flight. TECHNICAL NOTE.--Cut the pectoral muscles from the left side of the sternum, push back and pin to one side. With a strong pair of scissors cut through the ribs on the left side of the sternum and through the overlying bones. Lift the whole sternum, with the right pectoral muscle attached, to the left side of the pan and pin it down. Cut through the membrane which covers the viscera and cover the dissection with water. In this operation note the V-shaped _wishbone_ in front of the sternum. It is composed of the two _clavicles_ with their inner ends fused. Note the stout _coracoid_ bones extending from the anterior end of the sternum to the shoulder. Note near the middle of the body the _heart_ with the large blood-vessels proceeding from it. Behind the heart lies the large reddish-brown _liver_, and on the left side below the liver is the large _gizzard_ or _muscular stomach_. Note the _viscera_ folded over themselves in the body-cavity. Push them temporarily aside and note in the dorsal region under the heart large pinkish spongy sacs, the _lungs_. These are attached by short tubes, the _bronchi_, to the long cartilaginous _trachea_. At the union of the bronchi with the trachea is a small expansion with cartilaginous walls, within which are stretched small bands of muscles. This organ is the _syrinx_, the song- or voice-apparatus of the bird. It should be cut open and carefully examined. Trace the trachea forward to its anterior end. It opens by a _glottis_ into the _larynx_, a slightly swollen chamber with cartilaginous walls. Note the U-shaped _hyoid bone_ surrounding the front of the glottis. Through a blowpipe or quill inserted into the glottis blow air into the trachea and observe the inflation of the lungs and of certain large _air-sacs_ in the abdomen, which communicate with them.