394 DISSECTION OF THE RABBIT. 



Open up the descending cornu along its whole length, by 

 carefully cutting away the outer and ventral walls of the tem- 

 poral lobe. 



iv. The hippocampus major is a prominent convex 

 ridge, projecting into the floor and inner side 

 of the descending cornu, along its, whole 

 length (cf. fig. 67, p. 386). 



v. The corpus striatum is a thickened part of the 

 wall of the hemisphere, forming the outer side 

 and floor of the anterior part of the lateral 

 ventricle. It lies in front of the hippocampus 

 major, from which it is separated by a deep 

 groove, running obliquely backwards and out- 

 wards across the floor of the ventricle. 



Cut away carefully the outer wall of the anterior cornu of 

 the lateral ventricle, including the corpus striatum. 



vi. The septum lucidum is the thin vertical inner wall of 

 the hemisphere. It is placed opposite the corpus 

 striatum, and ventral to the corpus callosum. 



vii. The foramen of Monro is a small hole immediately beneath 

 the hinder border of the septum lucidum, through 

 which the lateral ventricle communicates with the 

 third ventricle, or cavity of the thalamencephalon. 



viii. The posterior pillar of the fornix is a narrow band lying 

 along the anterior edge of the hippocampus major. 

 Posteriorly it follows the hippocampus into the 

 descending cornu ; while anteriorly it becomes con 

 tinuous with its fellow of the opposite side in the 

 median plane, forming the body of the fornix, imme- 

 diately above the foramen of Monro. 



ix. The choroid plexus is a thin vascular fold of 

 the inner wall of the hemisphere project- 

 ing into the descending cornu in front of 

 the hippocampus major, and closely applied 

 to the anterior surface of the latter along its 

 whole length. 



x. There is a median vertical cleft between the right and 

 left hemispheres, the * fifth ventricle.' It lies below 



