382 DEVELOPMENT OF OEGANS IN MAMMALIA. [CHAP. 



By the fusion of the inner walls of the hemispheres 

 in front of the lamina terminalis a solid septum is 

 formed, continuous behind with the lamina terminalis, 



TRANSVERSE SECTION THROUGH THE BRAIN OF A SHEEP'S 

 EMBRYO OF 2*7 CM. IN LENGTH. (From KOlliker.) 



The section is taken a short distance behind the section 

 represented in Fig. 124, and passes through the posterior part of 

 the hemispheres and the third ventricle. 



st. corpus striatum ; ih. optic thalamus ; to. optic tract ; t. 



ventricle ; d. roof of third ventricle ; c. fibres of cerebr 

 peduncles ; c. divergence of these fibres into the walls of 1 

 hemispheres ; e. lateral ventricle with choroid plexus pi ; 

 h. cornu ammonis ; /. primitive falx ; am. alisphenoid ; 

 orbito-sphenoid ; sa. presphenoid ; p. pharynx ; mk. Meckel's 

 cartilage. 



