38'2 DISSECTION OF THE BABBIT. 



Sylvian fissures. In front, they project some 

 distance beyond the hemispheres. 



c. The infundibulum is a median rounded elevation, 



lying between the temporal lobes, about the 

 middle of the length of the brain : at its apex 

 is the rounded vascular pituitary body. This 

 latter is usually left behind in the pituitary fossa 

 in the base of the skull when the brain is removed, 

 and a slit-like aperture is then left at the apex 

 of the infundibulum, leading into the third 

 ven tricle. 



d. The optic c'hiasma is a transverse band of nerve- 



fibres, lying immediately in front of the infundi- 

 bulum. From its anterior border the optic 

 nerves arise, and from its outer ends the optic 

 tracts may be followed backwards towards the 

 optic lobes by gently pressing the temporal lobes 

 aside. 



e. The corpus mammillare, or corpus albicans, is a 



small rounded median elevation, immediately 

 behind the infundibulum. 



f. The pons Varolii is a stout band of transverse 



nerve-fibres, which crosses the ventral surface 

 of the medulla, opposite the posterior ends of the 

 hemispheres. It connects the two sides of the 

 cerebellum with each other. 



g. The crura cerebri are two large bands of nerve- 



fibres, immediately in front of the pons Varolii, 

 which run forwards, diverging from each other, 

 and connect the medulla oblongata with the 

 hemispheres. 



h. The medulla oblongata, as seen from the ventral 

 surface, is broad in front and gradually narrows 

 behind. It is marked by a median ventral fissure, 

 bordered by two narrow bands, the ventral 

 pyramids. At the outer sides of the pyramids, 



