270 



THE BRAIN OF QUADRUPEDS AND 



and also by the * fornix ' and ' lyra/ tlie description of 

 which will shortly follow.* 



Between the contiguous inner surfaces of the Thalami 



Fig. 87.— The Cerebral Hemispheres of the Dog, separ.ited, after division of the 

 Corpus Callosum, so as to expose the Ventricles and Basal Ganglia. (Fen-icr.) 

 1, Internal surface of left Hemisphere ; 2, Corpus Striatum ; 3, Thalamus ; 4, 5, 

 corpora quadrigemina ; G, anterior pillar of the fornix, divided on tlic left, undivided 

 on the right side (12) ; 7, the third ventricle, exposed by drawing the thalami 

 asunder; 8, the upper surface of the Cerebellum; 9, olfactory lobe or bulb; 10, 

 anterior commissure ; 11, corpus callosum, divided ; 13, middle commissure, ex- 

 tending across the third ventricle ; 14, pineal body, lying over and concealing the 

 posterior commissure ; 15, descending cornu of the lateral ventricle. 



there is a narrow space known as the Third Ventricle 

 (figs. 72, p; 87, 7). It is situated below the level of the 

 Lateral Ventricles, though each of these opens into it 



* By reference to fig. 87, it will be seen that the fornix (12) 

 constitutes the inner and posterior boundary of the Cerebral 

 Hemisphere, and that the Thalamus (3) Hes quite outside it and 

 its Ventricle — though the inspection of a horizontal section of 

 the hemisphere, as in fig. 86, might give rise to an entirely opposite 

 impression. 



