The early cartilaginous fibula is complete, but later the shaft is reduced and is usually represented by a fibrous cord which connects the two ends. In some cases, however, the upper part undergoes partial ossification, forming a slender rod which is usually united with the outer border of the tibia and is joined to the head by fibrous tissue. The =patella= is long, narrow, and very thick. The anterior surface is strongly convex and very rough and irregular. The articular surface is convex from side to side and nearly straight in the vertical direction. The large prominence on the inner side for the attachment of the accessory cartilage allows prompt determination of the side to which the bone belongs. The apex is more pointed than in the horse. The =tarsus= consists of five pieces; the central and fourth, and the second and third tarsal bones are fused. The =tibial tarsal= bone is relatively long and narrow, and is somewhat flattened from before backward. It bears a trochlea at either end. The groove and ridges of the proximal trochlea are not spiral, but almost sagittal; the outer ridge is the wider, and articulates with both tibia and fibula. The distal trochlea consists of two condyles divided by a groove, and articulates with the combined central and fourth tarsals. The posterior surface bears a large oval facet for articulation with the fibular tarsal; this occupies most of the surface, and is convex and grooved from above downward. The outer surface presents two facets for articulation with the fibular tarsal, and is excavated and rough elsewhere. The inner surface bears a tuberosity at its upper part, and is flattened below. The =fibular tarsal= bone is longer and more slender than in the horse. The distal part of the body is compressed laterally, and bears a projection in front which articulates with the external malleolus. The tuber calcis is marked posteriorly by a wide shallow groove, which is coated with cartilage in the fresh state. The =central= and =fourth tarsals= are fused to form a large bone (Os centrotarsale quartum, scapho-cuboid), which extends across the entire width of the tarsus and articulates with all of the other bones. The greater part of the upper surface is molded on the distal trochlea of the tibial tarsal, and its inner part rises high above the rest posteriorly. Externally there is a narrow undulating surface for articulation with the distal end of the fibular tarsal bone. The posterior surface bears two tuberosities, of which the outer one is rounded, the inner more prominent and narrower. The =first tarsal= bone is quadrilateral and small. It articulates with the central above, the metatarsus below, and the second tarsal in front.