xi BRAIN 531 



a thin wall, the lamina terminalis (/. /), and extends into the 

 infundibulurn below. At its anterior end are the foramina 

 of Munro (/. m), leading into the middle of the lateral 

 ventricles in the hemispheres (Fig. 141). In this region 

 each lateral ventricle is broad from side to side, but narrow 

 from above downwards ; it extends forwards into the frontal 



7 m 

 olf. 



FIG. 142. Rabbit. ^ Longitudinal vertical section of the rabbit's brain (nat. size). 

 Letters as in preceding figure ; in addition cb. central lobe of cerebellum, showing 

 arbor vitse ; c. c. crus cerebri ; c. h.^ parietal, and c. h2 temporal lobe ot 



choroid plexus ; //. optic nerve. (From Parker's Zootomy.) 



lobe, backwards into the parietal lobe, and downwards into 

 the temporal lobe. The olfactory lobes are solid. 



A prominent, convex ridge of white matter the hippocampus (Fig. 

 141, hp. m) projects into the inner side and floor of each lateral ven- 

 tricle where it descends into the temporal lobe, and closely applied to it 

 is a continuation of the choroid plexus (ch. pi], which passes from the 

 roof of the third ventricle into the lateral ventricle through the 

 foramen of Monro. In front of the hippocampus the outer side and 

 floor of the anterior part of the lateral ventricle is thickened to form an 

 eminence of grey matter, the corpus striatum (cp. j). Just beneath the 

 corpus callosum the internal wall of each lateral ventricle is thin, and 

 is known as the septum lucidum (sp. hi) ; and below it and above the 

 foramina of Monro is another commissure known as the body of the 

 fornix (Figs. 141 and 142, b. fo] which is continuous on either side with 



M M 2 



