BRAIN 



529 



The diencephalon consists of a right and left optic thalamus 

 (o. th.} between which is the slit-like third ventricle (v*) 



olf 



-olf 



FIG. 141. Two dissections of the rabbit's brain, from above (nat. size). In A, the 

 left hemisphere is dissected down to the level of the corpus callosum ; on the 

 right side the lateral ventricle is exposed. In B, the hemispheres are dissected 

 down to a little below the level of the anterior end of the corpus callosum ; only 

 the frontal lobe of the left hemisphere is retained, of the right a portion of the 

 temporal lobe also remains ; the choroid plexus arid pineal body are removed, as 

 , well as the greater part of the body of the fornix and the whole of its left posterior 

 pillar ; the cerebellum is removed with the exception of a part of its right lateral 

 lobe with the flocculus 



a. co. anterior commissure ; a.fo. anterior pillar of fornix ; a.pn. anterior peduncles 

 of cerebellum ; b.fo. body of fornix ; cb 1 . central lobe of cerebellum ; eft. its 

 lateral lobe; c.gn. elevation on the optic thalamus; c h. cerebral hemisphere; 

 ch.pl. part of choroid plexus ; cp. cl. corpus callosum ; cp. s. corpus striatum ; c. rs. 

 and d. p. elevations on the bulb \ ft. flocculus ; hp. m. hippocampus ; m.co. middle 

 commissure ; o. /*, o. ft. optic lobes ; olf. olfactory lobe ; o. th. optic thalamus ; o. 

 tr. optic tract (continuation of chiasma) ; p. co. posterior commissure ; p.fo. 

 posterior pillar of fornix ; pn. pineal body ; pd. pn. its peduncle ; /. pn. posterior 

 peduncles of cerebellum ; p. va. fibres of pons Varolii forming middle peduncles 

 of cerebellum ; sp. lu. septum lucidum ; st. 1. line on corpus callosum ; t. s. band 

 of white matter lying beneath choroid plexus ; v. vn. valve of Vieussens ; v&. 

 third ventricle ; tA. fourth ventricle. (From Parker's Zootomy.) 



roofed over by a thin membrane, continuous with a 

 vascular choroid plexus (Fig. 142, vl. ip\ and from its 



PRACT. ZOOL. \. MM 



