256 
ME.  J.  L.  CLAEKE  ON  THE  INTIMATE  STEHCTUEE  OF  THE  BEATS'. 
raphe  after  passing  through  and  around  their  nuclei.  I have  by  me  many  preparations 
showing  this  course  in  the  most  satisfactory  manner. 
(58.)  It  has  been  shown  that  the  grey  substance  behind  the  central  canal,  after  form- 
ing the  cells  in  the  post-pyramidal  ganglion,  becomes  itself  the  nucleus  of  the  eighth 
pair  of  nerves^  and  increases  by  encroaching  on  the  pyramid,  to  the  remains  of  which  it 
appears  again  to  contribute  for  the  formation  of  the  auditory  ganglion:  there  would 
seem,  therefore,  to  be,  if  I may  use  the  expression,  a kind  of  family  relationship  between 
these  two  vesicular  centres ; and,  moreover,  the  under  or  anterior  division  of  the  audi- 
tory nerve,  which  takes  its  origin  from  the  network  of  the  posterior  pyramid  behind 
the  caput  corntis  posterioris,  adjoins  the  upper  fibres  of  the  glossopharjmgeal,  as  the 
latter  do  those  of  the  vagus. 
Explanation  op  the  Plates. 
PLATE  XII. 
Fig.  1.  Under  surface  of  the  brain  of  the  Cod-fish: — A,  olfactory  neiwes,  attached  to  a 
delicate  membrane;  B,  optic  nerve,  drawn  aside;  C,  cerebral  hemisphere, 
slightly  wrinkled  or  folded ; D,  optic  lobe ; E,  anterior  column. 
Fig.  2.  Under  surface  of  the  brain  of  the  domestic  Fowl. 
Fig.  3.  Under  surface  of  part  of  the  brain  of  a young  Dog: — F,  crus  cerebri;  G,  pons 
Varolii;  H,  part  of  the  lateral  lobe  of  the  cerebellum;  s,  trape2dum;  vesi- 
cular column  on  the  outer  side  of  the  olive. 
Fig.  4.  Under  surface  of  a portion  of  the  brain  of  a Cat: — C',  C',  middle  and  posterior 
lobes  of  the  cerebrum. 
Fig.  5.  Posterior  surface  of  the  human  medulla  oblongata : — a,  restiform  body;  h,  h,  poste- 
rior pyramids ; d,  portio  mollis  of  the  seventh  nerve ; r,  r,  vesicular  columns 
or  nuclei  of  the  hypoglossal  nerves,  continuous  with  the  fasciculi  teretes ; 
t,  t,  pyriform  nuclei  of  the  vagus  nerves. 
Fig.  6.  Side  view  of  the  human  medulla  oblongata,  enlarged: — i,  anterior  ppamid; 
h,  olivary  column ; g,  lateral  column ; f,  tuber culo  cinereo,  or  expanded  ex- 
tremity of  the  posterior  cornu ; a,  restiform  body ; b,  posterior  pp’amids. 
Figs.  7,  8.  Side  views  of  the  medulla  oblongata  of  the  Sheep : — s,  trapezium ; s',  portio 
dura  of  the  seventh  nerve ; s",  fifth  nerve. 
Fig.  9.  Under  surface  of  the  medulla  oblongata  of  the  Cheetah,  or  hunting  Leopard. 
The  largely-developed  ardform  fibres  are  represented  on  the  right  side. 
Fig.  10.  Transverse  section  at  the  commencement  of  the  human  medulla  oblcmgata: — 
/,  caput  cornus,  or  expanded  extremity  of  the  posterior  cornu ; f",  posterior 
roots  of  the  first  cervical  nerve ; g",  spinal-accessory  nerve ; I,  anterior 
columns. 
