NERVOUS SYSTEM. 683 



side of the thalamencephalon, there is a rounded swelling, called the 

 corpus geniculatum. The roof of the third ventricle is formed by a 

 thin membrane or velum, with a plexus of blood vessels. In the 



JO. 



FIG. 336. Dorsal view of rab- 

 bit's brain. 



olf.L, Olfactory lobes', c.h., cere- 

 bral hemispheres ; a. I., optic 

 lobes (corpora quadrigemina) ; 

 cb., median part of cerebellum : 

 FL, flocculus of cerebellum ; 

 10, root of the tenth or vagus 

 nerve ; s.c., spinal cord. 



FIG. 337. Under surface of rabbit's 

 brain. After Krause. 



olf.L, Olfactory lobes ; o.t., olfactory tract ; 

 /.I., frontal lobe of cerebral hemisphere : 

 f/i., optic chiasma ; I.e., infundibulum ; 

 c.in., corpus mammillare ; 3, root of 

 oculomotor; 4, root of pathetic; 5, 

 root of trigeminal ; 6, root of abducens ; 

 7-8, roots of facial and auditory; Fl., 

 flocculus of cerebellum; H. , i2th or 

 hypoglossal nerve ; 10, roots of vagus ; 

 9, the line runs in front of the root of 

 the glosso-pharyngeal to the root of 6 ; 

 p.v., pons Varolii. 



anterior wall of the third ventricle lies the small anterior commissure ; 

 across the third ventricle the large middle commissure runs ; in the rool 

 of the hind part of the ventricle lies a small posterior commissure. 

 The optic lobes are fourfold corpora quadrigemina. They are in 



