XIII 



PHYLUM CHORDATA 



577 



interior of the hemispheres are of large size and somewhat complex 

 form. 



The optic lobes, which are relatively small, are divided into four 

 parts, and are hence called the corpora quadrigemina. The 



Rol 



Fit:. 1202. -Brain of Dog. A, dorsal ; B, ventral ; C, lateral aspect. B. ol. olfactory bulb ; Cr. ce. 

 crura cerebri ; Fi. p. great longitudinal fissure ; Hff, HH', lateral lobes of cerebellum ; Hyp. 

 hypophysis ; Med. spinal cord ; NH, medulla oblongata ; Po. pons Varolii ; VH. cerebral 

 hemispheres ; IFv, middle lobe (vermis) of cerebellum ; I XII. cerebral nerves. (From 

 Wiedersheim's Comparative Anatomy.) 



pineal body is always a small, gland-like structure. Connecting 

 together the lateral parts of the cerebellum, which, in the higher 

 Mammals, attains a high degree of development, is a transverse 

 flattened band the pons Varolii (Po.) crossing the hind-brain 

 on its ventral aspect. 



