3. Four _branchial_ nerves, which can be seen through the floor of the anterior cardinal vein, leave the outer side of the vagus trunk. Each divides into a pretrematic and posttrematic branch; a pharyngeal branch, the last of which is the largest, arises from each posttrematic. 4. Beyond the branchial nerves the remainder of the vagus passes backward as the _intestinal_ or _visceral_ trunk, to the end of the pharynx, where it divides into a number of branches which are distributed chiefly to the wall of the stomach. Near the point of this last division the vagus is crossed by the hypobranchial nerve, which should be noted and preserved. The _occipital nerve_ penetrates the lateral wall of the cranium close behind the root of the vagus and enters the canal of the vagus, along which it passes. On emerging, it sends small branches to the nearby muscle, while the principal portion runs on to join the hypobranchial nerve. The occipital nerve will be found to arise from the ventral surface of the medulla, below and behind the root of the vagus, by two or more distinctly separated roots, which may represent distinct nerves. SPINAL NERVES. The spinal nerves are those nerves which arise from the sides of the spinal cord. They differ from the cranial nerves not only in their origin outside the cranium, but also in that each spinal nerve arises by two roots which spring from the spinal cord near the dorsal and ventral surfaces. Each root passes through a foramen in the cartilaginous wall of the neural canal, the ventral a little anterior to the dorsal, after which they unite to form the spinal nerve. Between the junction of the roots and its foramen the dorsal root contains a mass of ganglion cells, which cause an enlargement known as the _dorsal root ganglion_. The typical course of a spinal nerve is around the body to the ventral surface, giving off branches to the muscles and skin of its segment. A short distance from the vertebral column the spinal nerves lie just outside the peritoneum, through which many of them can be seen and followed to about the level of the lateral vein. At this point they pass outward into the muscles of the body wall. To dissect any of the spinal nerves make a longitudinal incision along the lateral line and separate the dorsal muscle mass from the lateral muscles for some distance. The dorsal muscles can then be pressed toward the vertebral column and dissected away from the peritoneum. The spinal nerves, lying against the peritoneum, will be exposed and can be followed easily, first to their roots, next ventrally.