[Illustration FIG. 89. FIRST AND SECOND THORACIC VERTEBRAE OF AN OX (_Bos taurus_) × 1/3. (Camb. Mus.) 1. neural spine. 2. neural canal. 3. prezygapophysis. 4. facet for articulation with the tuberculum of the rib. 5. facet for articulation with the capitulum of the rib. 6. postzygapophysis. 7. foramen for exit of spinal nerve.] In the Proboscidea there are twenty-three thoraco-lumbar vertebrae, of which nineteen or twenty bear ribs. In the RODENTIA there are generally nineteen thoraco-lumbar vertebrae but occasionally the number rises as high as twenty-five. In the Hares (Leporidae) the number is nineteen, twelve or thirteen of which are thoracic. The anterior thoracic vertebrae have short centra and high backwardly-directed neural spines, the lumbar vertebrae have large forwardly-and downwardly-directed transverse processes with expanded ends. Metapophyses, anapophyses and hypapophyses are all present. In the Agouti (_Dasyprocta_) the convergence of the neural spines to a centre of motion is very strongly marked. In the CARNIVORA the trunk vertebrae are nearly always twenty or twenty-one in number; in the genera _Felis_ and _Canis_ thirteen of these are thoracic and seven lumbar. The anterior thoracic vertebrae have long backwardly-projecting neural spines, while the posterior thoracic and lumbar vertebrae have shorter and thicker neural spines which project slightly forwards. In the Pinnipedia there is no change in the direction of the neural spines, and anapophyses are but little developed. In the INSECTIVORA the number of trunk vertebrae varies much from nineteen--thirteen thoracic and six lumbar--in _Tupaia_, to twenty-four--nineteen thoracic and five lumbar--in _Centetes_. The development of the various processes varies in accordance with the habits of the animals, being great in the active forms, slight in the slowly moving or burrowing forms. In _Talpa_ and _Galeopithecus_ the intervertebral discs of the thoraco-lumbar region instead of being cartilaginous have ossified forming inter centra, a condition met with in very few mammals. In the CHIROPTERA there are seventeen or eighteen thoraco-lumbar vertebrae, eleven to fourteen of which may bear ribs. The development of processes is slight. Among PRIMATES the number of trunk vertebrae is generally nineteen, of which twelve to fourteen bear ribs; in man and the Gorilla and Chimpanzee the number is, however, seventeen, and in the Orang (_Simia_) sixteen. In some of the Lemuroidea there are as many as twenty-three or twenty-four. In most cases the neural spines converge more or less to a centre of motion, and this is especially marked in some of the Lemurs; it does not occur in man and the anthropoid apes. SACRAL AND CAUDAL VERTEBRAE.