VII. HIP JOINT. The hip joint is formed by the pelvis and femur bone. This is a true ball-and-socket joint similar to the shoulder joint. It has a capsular, and is called the round ligament, in the joint, holding the head or ball on the femur in the socket of the pelvis. This can be seen plainly by examining the joint. This round ligament is important, as it often becomes strained, being the seat of hip joint lameness. It is also held together by the strong muscles of the hip. Its motion is rotation similar to that of the shoulder joint. VIII. STIFLE JOINT.--This joint is formed above by the lower end of the femur, or hip bone, and the upper end of the tibia or thigh bone. These two bones in front form a pulley-like surface on which the patella, or stifle bone, is situated. This bone, when the joint is in motion, glides up and down over the pulley-like surface. It sometimes becomes displaced, and this is termed dislocation of the patella or stifle bone. This is an important point to notice about this joint. It has a capsular and lateral, or binding ligament, which hold the stifle bone to its place as it plays upon the pulley-like process of this joint. The action of this joint is only forward and backward or flexion and extension. It has no lateral or side motion. IX. TARSUS OR HOCK JOINT.--This joint contains six bones. The two upper bones, one of which is a pulley-like bone placed in front, and the other placed behind, forms that portion of the hock which is called the point of the hock to which the muscles of the gambe are attached. It can be easily seen or felt. The upper surface of these two bones articulate with the lower portion of the tibia or thigh bone, and forms a true articulation of the hock joint. This part is what gives most of the motion to the joint. Below these are three other small, irregular bones, placed one upon the other, having an articular surface between them. Immediately behind these three small bones is what is called the cuboid bone. This bone also articulates with the three small irregular bones, helping to form the articular surface of the hock. The lower articular surface helps to give a small amount of motion to the joint. This joint is the seat of bone or bog spavin due to severe sprains, or poorly conformed joints. Fetlock, pastern and coffin joints of the hind leg are so closely allied to those of the fore leg that it is not worth while discriminating between them. CHAPTER III. MYOLOGY. The branch of anatomy which treats of the muscular system is called Myology.