126 



THE BRAIN OF REPTILES 



they show a transverse fissure which divides the two bodies 

 into four parts, corresponding to the * corpora quadrigemina' 



FIG. 58. Brain and Cranial Nerves of Boa Constrictor. (Rymer Jones, after Swan.) 

 a, Cerebral lobes ; b, optic lobes with transverse depression ; c, cerebellum ; d, mem- 

 brane of the nose ; 1, olfactory nerve ; 2, optic nerve ; 3, third, or common oculo- 

 muscular nerve ; 4, fourth, or trochlear nerve to the superior oblique muscle of the 

 eye; 5, first trunk of the fifth; 6, second trunk of the fifth; 7, third trunk of the 

 fifth ; 8, hard portion of the seventh nerve ; 9, auditory nerve ; 10, glosso-pharyngeal 

 nerve ; 11, trunk of the vagus nerve ; 12, ninth nerve. The last three nerves are 

 intimately connected with one another, and with 13, a sympathetic ganglion 



