XII.] THE HIND-BKAIN. 369 



lobe with an arbor vitse, into which the fourth ventricle 

 is prolonged. There are two small lateral lobes, ap- 

 parently equivalent to the flocculi. 



In Mammalia the cerebellum attains a still greater 

 development. The median lobe or vermiform process 



FIG. 119. 



LONGITUDINAL SECTION THROUGH THE BRAIN OF A CHICK OF 

 TEN DAYS. (After Mihalkovics.) 



hms. cerebral hemispheres ; alf. olfactory lobe ; alf^ olfactory 

 nerve ; ggt. corpus striatum ; oma. anterior commissure ; 

 did 3. choroid plexus of the third ventricle ; pin. pineal 

 gland ; cmp. posterior commissure ; trm. lamina terminalis ; 

 chm. optic chiasma ; inf. infundibulum ; hph. pituitary body ; 

 bgm. commissure of Sylvius (roof of iter a tertio ad quartum 

 ventriculum) ; vma. velum medullse anterius (valve of Vieus- 

 sens) ; cbl. cerebellum ; chd 4. choroid plexus of the fourth 

 ventricle ; obt 4. roof of fourth ventricle ; obi. medulla oblon- 

 gata ; pns. commissural part of medulla ; inv. sheath of 

 brain ; bis. basilar artery ; crts. internal carotid. 



F. & B. 24 



