AMPHIBIA. 67 



PLATE XVIII. 



FIG. I. 



THE ORIGIN OF THE CEREBRAL NERVES OF 



THE SNAKE. 



(BOA CONSTRICTOR.) 

 THE figures of this and the following plate are the exact size of a snake nine 



feet 



c. Anterior lobe of the brain ; b. Optic lobe ; c. Cerebellum ; d. Schneiderian 

 membrane of the nose. 



1. Olfactory nerve ; it is fibrous, and different from the soft texture of the brain ; 



it is joined by the first trunk of the fifth near its entrance at the nose, and 

 the branches proceeding from it are then distributed over the Schneiderian 

 membrane. 



2. Optic nerve. 



3. Third or common oculo-muscular nerve cut short. 



4. Fourth nerve given to the superior oblique muscle of the eye. 



5. First trunk of the fifth ; it passes forward first within the cranium, then into 



the orbit, and from this part to the Schneiderian membrane, on which it 

 becomes connected with the olfactory nerve. 



6. Second trunk of the fifth. 



K 2 



