The _thorax_ is formed by the ribs and the breast-bone or sternum. The horse has eighteen ribs on each side (7), and all articulate with the dorsal vertebræ. The first eight pairs unite by their lower ends directly to the sternum or breast-bone, and are therefore called _true ribs_, while the last ten pairs are only indirectly attached to the sternum, and are consequently called _false ribs_. The sternum (8) lies between the forelegs, and helps to form the floor of the chest cavity. The space enclosed by the bones of the thorax is called the thoracic, pulmonary, or chest cavity, and contains the heart and lungs. The _bones of the pelvis_ form a complete circle or girdle. The upper part, called the ilium (9′), articulates on its inner side with the sacrum (5), while its outer side is prolonged to form a prominent angle, which is the support of the hip, and is called the “point of the hip.” The posterior part of the pelvis is called the ischium (9″), and that part lying between the ilium and the ischium and forming part of the floor of the pelvis is called the pubis. The space between the thorax and the pelvis, bounded above by the lumbar vertebræ and shut in below and on the sides by the skin and muscular walls of the belly (abdomen), is called the _abdominal cavity_. This cavity opens directly into the pelvic cavity, and contains the stomach, intestines, liver, spleen, pancreas, kidneys, and a part of the generative organs. The thoracic and abdominal cavities are separated by a muscular partition, the _diaphragm_. The =bones of the limbs= may be likened to columns, upon which the body rests; they articulate with one another at various angles, are tubular in structure, and strong. The bones of the =fore-limbs= _do not articulate directly with the bones of the trunk_, but are attached to the body by means of the skin and muscles. From above to below we distinguish the following bones: 1. The _scapula_, or shoulder-blade (10), a flat, triangular bone, prolonged at its upper border by a flat, very elastic cartilage, called the scapular cartilage. At its lower end the scapula articulates with— 2. The upper end of the _humerus_ (11), forming the _shoulder-joint_ (scapulo-humeral articulation). The humerus articulates at its lower end with— 3. The _radius_ (12) and the _ulna_ (13), to form the _elbow joint_. These two bones are the basis of the _forearm_. The ulna, smaller and weaker than the radius, lies behind and projects above it to form the point of the elbow. The lower end of the radius articulates with— 4. The _carpus_, or _knee_ (14), which comprises seven small, cubical bones disposed in two horizontal rows, one above the other. The upper row comprises four bones and the lower row three. The lower row rests upon—