Thirteen pairs of ribs are present, of which nine are sternal and four asternal. They are strongly curved, narrow, and thick. Those in the middle of the series are the longest. The first eight or nine increase in width in their lower part. The last rib is usually floating. The costal cartilages are long and curve forward; the length and curvature of the first pair is a striking special feature. [Illustration: FIG. 120.—FOURTH LUMBAR VERTEBRA OF DOG, LEFT VIEW. _a_, _b_, Articular surfaces of body; _c_, transverse process; _d_, accessory process; _e_, anterior articular process; _e′_, mammillary process; _f_, posterior articular process; _g_, spinous process. (Ellenberger-Baum, Anat. d. Hundes.) ] [Illustration: FIG. 121.—SACRUM OF DOG, DORSAL VIEW. _a_, Dorsal sacral foramina; _b_, articular surface of body of first segment; _c_, _d_, anterior articular processes; _e_, wing; _f_, rudiments of articular processes; _g_, lateral part; _h_, spinous processes. (Ellenberger-Baum, Anat. d. Hundes.) ] THE STERNUM This is long, laterally compressed, and consists of eight sternebræ, which fuse only in exceptional cases and in extreme old age. The first segment is the longest; its anterior end is blunt-pointed and bears a short conical cartilage. It widens at the point of articulation of the first pair of cartilages. The last segment is also long, thinner than its predecessors, wide in front, and narrow behind, where it bears a narrow xiphoid cartilage. The =thorax= is distinctly barrel-like and is not decidedly compressed anteriorly like that of the horse and ox. The inlet is oval and is relatively wide on account of the marked curvature of the first pair of ribs and cartilages. BONES OF THE SKULL In the following descriptions of the separate bones an intermediate type—_e. g._, a fox terrier—is selected, and the most striking differences in the brachycephalic and dolichocephalic breeds will be considered in the section on the skull as a whole. CRANIUM [Illustration: FIG. 122.—BASE OF SKULL OF DOG, WITHOUT MANDIBLE.