312 ANATOMY OF VERTEBRATES. 



respective destinations at the middle of the floor of the orbit: 

 the hindmost branch, continuous with a filament from the 

 acoustic nerve, unites with a branch of the vagus, and is distributed 

 like the ( portio dura ' of the ' seventh ' nerve. The distinct 

 origin of this nerve, between the ( fifth ' and acoustic, is shown 

 in the Python, fig. 188, s; it communicates, fig. 206,6, with 

 the ganglion, ib. i, of the sympathetic, then passes through the 

 6 apertor oris,' to which it gives a branch ; communicates with 

 the first spinal nerve, and terminates on the ( costo-mandibularis ' 

 muscle. The acoustic nerve, fig. 188, 9, soon divides, and enters 

 the labyrinth by two or more foramina. The glosso-pharyngeal, 

 fig. 188, 10, is distinct at its origin in Serpents and higher Reptiles. 

 In Batrachia it issues from the ganglion of the vagus. In the 

 Python the glosso-pharyngeal passes chiefly to the ganglion, 

 fig. 206, i, of the sympathetic. The 'nervus vagus,' fig. 188, 11, 

 arises by several filaments, and in the Chelonian and Crocodilian 

 reptiles is recruited by an ( accessorius,' arising from the tract of 

 the first and second spinal nerves. In the Python, fig. 206, 8, 

 the vagus communicates with the sympathetic, and then receives 

 the continuation of the glosso-pharyngeal from the ganglion, i. 

 It sends a branch to communicate with the ' ninth,' and to be 

 distributed to the muscles and membrane of the fauces. The 

 trunk is then continued down or back, close to the trachea and 

 jugular vein: on the left side it also accompanies the carotid 

 artery : it sends filaments along the large vessels to the heart, and 

 others behind each aorta, similar to the recurrent nerves, to be 

 distributed upon the trachea and esophagus : each trunk for a 

 short space accompanies the corresponding pulmonary artery to 

 the lung. Before reaching the liver it passes ventrad of the 

 lung for a short distance, and joins its fellow to form a single 

 nerve. This is continued under the capsule of the liver supplying 

 that organ, the lungs, and oesophagus. Near the end of the liver 

 the vagus sends a large branch, which communicates freely with 

 the sympathetic, to the left surface of the stomach, and this also 

 gives filaments to the contiguous part of the lung. The trunk, 

 on the right of the stomach, communicating with the sympathetic, 

 and with the division on the left, is continued a short way on the 

 membrane connecting the viscera, gives branches to the right side 

 of the stomach, and terminates on the beginning of the intestine, 

 at the pancreas. 



In the Chelonia and Crocodilia the vagus quits the skull by two 

 or three of its roots, which unite outside to form the trunk of the 

 nerve ; its communication with the glosso-pharyngeal, the ninth, 



