XII.] THE HIND-BRAIN, 869 



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 

 i development. The median lobe or vermiform process 



Fig. 119. 



yocn, Cfnp b,m. 



Longitudinal Section through the Brain of a Chick op 

 Ten Days. (After Mihalkovics.) 



hms. cerebral hemispheres ; alf. olfactory lobe ; a^/i, olfactory 

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

 chd 3. choroid plexus of the third ventricle ; fin. pineal 

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

 dim. optic chiasma ; inf. infundibulum ; hpli. pituitary body ; 

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

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

 sens) ; chl. cerebelkun ; chd 4. choroid plexus of the fourth 

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

 gata ; jo%s. co m missural part of medulla ; inv. sheath of 

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



F. & B. 24 



