AMPHIBIA. 43 



anterior part of the mouth and palate. The prolongation communicates with the 

 ninth nerve ; it passes down the spine and communicates with the eleven superior 

 spinal nerves ; it emerges on each side at the place the superior branches of the 

 vertebral artery enter to distribute branches in the intercostal spaces ; it is continued 

 downwards in a very fine plexiform prolongation with the vertebral artery, as far as 

 the origin from the right aorta ; it then branches to each side beneath the membrane 

 connecting the viscera with the ribs and spine, and communicates \vith filaments of 

 the par vagurn ; it is afterwards continued downwards, receiving a filament from each 

 spinal nerve. In its course it is a very fine nerve, and has not any more ganglia than 

 the first, and those communicating with the second trunk of the fifth ; but at different 

 points, from which the nerves pass to the viscera, there is an appearance of a delicate 

 plexus : this plexiform structure varies in different parts, and becomes much greater 

 about the beginning of the intestine, where it resembles that corresponding with the 

 semilunar ganglion in the turtle ; near the kidney it assumes the form of a nervous 

 membrane or retina before it is distributed on the urinary and generative organs. 

 Branches pass from the plexuses with the arteries to the different viscera. In the 

 frog, there is a ganglion connected with the upper part of the par vagum ; it sends a 

 branch upwards to communicate with the branch of the fifth passing to the palate ; 

 the prolongation downwards is formed from branches of the spinal nerves, which 

 communicate with each other before they terminate on the viscera. In the crocodile, 

 the sympathetic nerve is continued down the neck, in a canal like that of the vertebral 

 artery in birds, and then underneath a process from the head of each of the three 

 superior ribs; it is continued in the thorax double from one ganglion to another. 

 The branches of the sympathetic form a plexus instead of a semilunar ganglion, from 

 which branches proceed to the stomach, liver, and intestines. Branches then pass to 

 the ovary and kidney, and appear to have a disposition between that in the turtle and 

 snake ; the sympathetic passes down and forms a junction with that of the opposite 

 side on the caudal artery, along which it is continued into the tail, nearly as in the 

 calf and porpoise. The ganglia throughout the sympathetic are not distinct. 



In an alligator six feet long, there is a small prolongation descending on the 



G 2 



