The =second= and =third tarsals= are fused to form a rhomboid piece. The proximal surface is concavo-convex, and articulates with the central component. The distal surface is undulating and rests on the metatarsus. The external surface bears a small facet in front for the fourth tarsal component, and the posterior surface a very small one for the first tarsal bone. The =large metatarsal= bone is about one-seventh (ca. 3 cm.) longer than the corresponding metacarpal. Its shaft is compressed laterally and is distinctly four-sided. The groove on the anterior surface is deep and wide. The posterior surface is marked by variable grooves. The upper foramen on this surface does not perforate the shaft, but passes obliquely through the extremity, opening on the posterior part of its proximal surface. The postero-internal angle of the proximal end bears a facet for articulation with the small metatarsal bone. [Illustration: FIG. 104.—SKELETON OF DISTAL PART OF LEFT HIND LIMB OF OX, INTERNAL VIEW. _24_, Tuber calcis; _25_, large metatarsal bone; _30_, first phalanx; _31_, second phalanx; _32_, third phalanx. (After Ellenberger-Baum, Anat. für Künstler.) ] The =small metatarsal= bone is a quadrilateral disc a little less than an inch in width and height. Its anterior face bears a facet for articulation with the large metatarsal bone. The large metatarsal bone is usually regarded as consisting of the fused third and fourth metatarsal bones. The medullary cavity is subdivided like that of the large metacarpal bone. Some anatomists, however, consider that the ridges at the upper end of each border represent the second and fifth metatarsals (Rosenberg and Retterer). On this basis the small bone would be the first metatarsal. The =phalanges= and =sesamoids= resemble those of the thoracic limb so closely as to render separate description unnecessary. SKELETON OF THE PIG VERTEBRAL COLUMN The =vertebral formula= is C_{7}T_{14–15}L_{6–7}S_{4}Cy_{20–23}. [Illustration: FIG. 105.—SKELETON OF PIG, LATERAL VIEW.