NEEVOUS SYSTEM. 



317 



weight is about twenty-two ounces, in the sheep about five 

 ounces. It is ovoid in shape. Viewed on its superior surface 

 (fig. 163), we shall see the following areas, starting from behind, 

 where it joins the spinal cord : The medidla or isthmus (B), a 

 kind of white peduncle running into the brain, the prolongation 

 as it were of the spinal cord : following this is a grey trilobed 





Pig. 164. — Bbain of Hobse (ventral view). 



01, Olfactory lobes; CI and C2, cerebmm; Cb, cereliellum ; M, medulla; Op.C, optic 

 chiasma; Pt, pituitary gland ; Cc, crura cerebri; P, pons Varolii ; 1-10, roots of cranial 

 nerves. 



mass, the cerebellum (C), and in front of the cerebellum are seen 

 two other lobes separated by a deep fissure from the cerebellum 

 and from one another (1) ; these two lobes are the cerebral lobes, 

 the whole forming the cerebrum (2-14). The cerebral hemi- 

 spheres are more or less convoluted. On examining the under- 

 surface of the brain (fig. 164) it wiU be seen that the peduncle 



