XII.] 



THE CEREBRAL COMMISSURES. 



381 



hemispheres. These commissures are (1) the anterior 

 commissure, (2) the fornix, and (3) the corpus callosum, 

 the two latter being peculiar to Mammalia. 



Fig. 124. 



//?- 



Transverse Section through the Brain of a Sheep's 

 EiiBRTO OF 2-7 CM. IN LENGTH. (From KoUiker.) 



The section passes through the level of the foramen of 

 ]\Ionro. 



St. corpus striatum ; m. foramen of Monro ; t. third ventricle ; 

 pi. choroid plexus of lateral ventricle ; f. falx cerebri ; th. 

 anterior part of optic thalamus ; ch. optic chiasma ; o. optic 

 nerve ; c. fibres of the cerebral peduncles ; h. cornu am- 

 monis ; p. pharynx ; sa. pre- sphenoid bone ; a. orbito- 

 sphenoid bone ; s. points to part of the roof of the brain at 

 the junction between the roof of the third ventricle and 

 the lamina terminalis ; I. lateral ventricle. 



