5. The large metacarpal or _cannon bone_, and the two rudimentary metacarpal or _splint-bones_. The lower end of the radius, the upper ends of the metacarpal bones, and the small carpal bones together form the carpal or _knee-joint_ (wrist of man). Of the metacarpals, the middle one is the largest, longest, strongest, and most important, and is called the _large metacarpal_, _cannon_, or _shin-bone_ (15). It articulates at its lower end with the os suffraginis, or long pastern (17), and with the two small sesamoid bones (20). On each side of the upper part of its posterior surface lie the two long, slender splint-bones (16). The inner splint-bone is sometimes affected with bony thickenings (exostoses) called “splints.” 6. The bones of the _phalanges_ (all bones below the cannon) will be fully described in another place. The bones of the =hind limbs= articulate _directly_ with the pelvis at the hip-joint. They are stronger than the bones of the anterior limbs. We distinguish the following bones in the hind legs: 1. The highest bone in the hind limb is the _femur_ (21). It is the strongest bone in the entire body. It lies in an oblique direction downward and forward, and at its lower end articulates with— 2. The _patella_ (22), the _tibia_ (23), and the _fibula_ (24), to form the _stifle-joint_ (knee of man). The patella plays over the anterior surface of the lower end of the femur. The fibula is small, and lies against the upper and outer side of the tibia. The latter at its lower end articulates with— 3. The bones of the tarsus, or _hock_ (25), which are six small, irregular bones disposed in three rows, one above another. The _os calcis_, or _heel-bone_, and the _astragalus_ are in the uppermost row, and are the most important. The former projects above the true hock-joint from behind, to form a long lever, the upper end of which is called the “point of the hock,” and the latter articulates with the tibia. The tarsal (hock) bones articulate below with— 4. The _metatarsal bones_ (26 and 27), which are longer, and the cannon narrower from side to side, than the corresponding metacarpal bones, but are otherwise similar. 5. The _phalanges_ of a hind limb (28 to 31) are also narrower than those of a fore-limb, but are nearly alike in other respects.