XIII.] THE FEOG. 17 



be called a distinct corpus striatum. The inner wall forn 

 one or two convex projections into the ventricle. 



In the bases of the olfactory lobes the forward continuj 

 tion of the ventricular cavity is very narrow and the lob( 

 become nerve-like , cords, which leave the skull and sprea 

 out on the posterior faces of the olfactory sacs. 



The inner faces of the hemispheres are quite free an 

 separated by a cleft, . the great fissure, but the inner fac( 

 of the commencements of the olfactory lobes are close! 

 united together, giving rise to a kind of corpus callosum. 



There are ten pairs of cranial nerves ordinarily so callei 

 though it is to be recollected that the first and second pai: 

 are proved, by their development, to be lobes of the brain. 



1. Olfactorii. 



The olfactory lobes are what answer to the so-calh 

 olfactory nerves of the higher Vertebrata, They a 

 distributed exclusively to the olfactory sacs. 



2. Optici. 



These diverge from the base of the brain in front 

 the infundibulum. They are originally outgrowths 

 the thalamencephalon which secondarily become co 

 nected with the optic lobes. 

 Of the remaining cranial nerves five pairs leave the ski 

 in front of the auditory capsules, while one pair enters the 

 capsules and two pairs pass out behind the capsules. 

 The prseauditory nerves are the following. 



3. Motores oculorum 



arise from the front part of the floor of the mid-bn 

 and are distributed to all the muscles of the e 

 except the external rectus, the superior oblique a 

 the retractor bulbi, 



12—2 



