62 DISSECTION OF THE CAT 



Carefully remove the corpus callosum and expose 

 the cavity below. 



3. The Lateral Ventricles are the two irregular- 

 shaped cavities, extending below the corpus cal- 

 losum, through the greater part of each hemi- 

 sphere. The anterior portion of the ventricle, 

 which is continued forward and downward into 

 the anterior part of the hemisphere, is the anterior 

 cornu. The continuation of the ventricle back- 

 ward and downward forms the descending cornn, 

 while the reduced posterior part is the posterior 

 cornu. (Plate VII., B.) 



4. The Septum Lucidum is the partition separating 

 the anterior cornua of the two lateral ventricles. 



5. The Corpus Striatum is the more or less oval 

 mass, projecting into the cavity of the anterior 

 cornu from its outer wall. (Plate VII., B.) 



6. The Hippocampus Major is the large oval pro- 

 jection forming the floor of the posterior part of 

 the lateral ventricle and descending cornu. Over 

 its surface passes a thin vascular layer, the choroid 

 plexus. (Plate VII., B.) 



7. The Fornix is formed by two bands of fibres 

 (the anterior pillars of the fornix}, which pass 

 dorsally from the corpora albicantia, and unite just 

 under the anterior end of the corpus callosum. 

 The triangular sheet formed by then; union (the 

 body of the fornix) lies immediately under the 

 corpus callosum. Posteriorly it again divides into 



