In the SIRENIA there are a very large number of ribs noticeable for their great thickness and solidity, but not more than three are attached to the sternum. CETACEA. In the Whalebone whales the ribs are remarkable for their very loose connection both with the vertebral column and with the sternum. The capitula are scarcely developed, and the attachment of the tubercula to the transverse processes is loose. The first rib is the only one connected with the sternum. In the Toothed whales the anterior ribs have capitula articulating with the centra, as well as tubercula articulating with the transverse processes; in the posterior ones, however, only the tubercula remain. Seven pairs of well-ossified sternal ribs generally meet the sternum. In the Physeteridae most of the ribs are connected to the vertebrae by both capitula and tubercula. In the UNGULATA the ribs are generally broad and flattened, and this is especially the case in the genera _Bos_ and _Bubalus_ (fig. 101, 6). The anterior ribs are short and nearly straight, and sternal ribs are well developed. The Artiodactyla have twelve to fifteen pairs of ribs, the Perissodactyla eighteen or nineteen, and _Procavia_ twenty to twenty-two. The Elephant has nineteen to twenty-one pairs, seven of which may be floating ribs. [Illustration FIG. 101. SKELETON OF A CAPE BUFFALO (_Bubalus caffer_). The left scapula is omitted for the sake of clearness × 1/17. (Brit. Mus.) 1. premaxillae. 2. nasal. 3. orbit. 4. neural spine of first thoracic vertebra. 5. scapula. 6. rib. 7. femur. 8. patella. 9. tibia. 10. metatarsals. 11. radius. 12. metacarpals.] In the RODENTIA there are generally thirteen pairs of ribs, which do not present any marked peculiarities. The CARNIVORA have thirteen to fifteen pairs of ribs, whose vertebral portions are slender, nearly straight and subcylindrical, while their sternal portions are long and imperfectly ossified (fig. 76, 5). There is nothing that calls for special remark about the ribs, in either INSECTIVORA or CHIROPTERA. PRIMATES. In Man and the Orang (_Simia_) there are generally twelve pairs of ribs; in the Gorilla and Chimpanzee (_Anthropopithecus_), and Gibbons (_Hylobates_), there are thirteen, in the Cebidae twelve to fifteen, and in the Lemuroidea twelve to seventeen pairs. The first vertebral rib is shorter than the others, and the sternal ribs generally remain cartilaginous throughout life, though in man the first may ossify. APPENDICULAR SKELETON. THE PECTORAL GIRDLE.