XtT.] THE HIND-BRAIN. 369 



lobe with an arbor vitiB, 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. 



o6l 

 4*i cris in/ lU fi'^ 



Longitudinal Section theodqh the Brain of a Chick of 

 Ten Days. (After Mihalkovics.) 



hms. cerebral hemispheres ; alf. olfactory lobe ; aZ/i, olfactory 

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

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

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

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

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

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

 sens) ; d)l. cerebellum ; did 4. choroid plexus of the fourth 

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

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

 brain ; hU. basilar artery ; orti. internal carotid. 



P. & B. 24 



