[Illustration: FIG. 52.--TARSUS OF THE OX: POSTERIOR LEFT LIMB, ANTERO-EXTERNAL SURFACE. 1, Tibia; 2, coronoid bone of the tarsus; 3, superior articular surface of the astragalus; 4, inferior articular surface of the astragalus; 5, calcaneum; 6, cuboido-scaphoid bone; 7, great cuneiform bone--the small cuneiform bone is situated at the back of the latter; 8, principal metatarsal--the small, or rudimentary, metatarsal bone is very small; it is situated at the back of the preceding, and is not to be seen in the sketch. It would be visible if the view were directly lateral, but then the superior and inferior articular surfaces of the astragalus would be less apparent.] The fibula is extremely atrophied. The shaft and superior extremity of this bone are represented merely by a simple ligamentous cord, which is sometimes ossified. There remains of the fibula, as a portion well and distinctly developed, the inferior extremity only. This presents itself under the form of a small bone situated in the region ordinarily occupied by the inferior extremity of the outer bone of the leg--that is to say, the external part of the inferior extremity of the tibia; this little bone articulates with the astragalus and the calcaneum. Some authors consider it to be a tarsal bone, and describe it under the name of the coronoid bone of the tarsus (Fig. 52, 2). It is not, perhaps, quite legitimate to describe it as a bone of this region, for it has not a homologue in the tarsus of other animals. Its external surface is rough; its superior border is furnished with a small pointed process occupying a depression which is provided for it by the tibia. It reaches lower down than the latter, and forms in this way a sort of external malleolus, which frames, on the outer aspect, the mortise in which the astragalus is maintained. The tarsus, as a whole, has an elongated form; it is formed of five bones: the astragalus, calcaneum, cuboid and scaphoid, which coalesce, to form a single bone, and two cuneiform bones, which correspond to the second and third cuneiform bones of the human foot. These cuneiforms are called, from their size, commencing internally, by the names small and great cuneiform. The calcaneum is long and narrow; it is longer than that of the horse; it is on the anterior and external part that the bone (coronoid tarsal bone) which represents the inferior extremity of the fibula is situated. It forms the prominence known as _the point of the ham_, a prominence which is no other than the heel, which, in the unguligrades, is, as we have already said, very far removed from the ground.