﻿Nervous 
  System 
  of 
  Ceratodus 
  Forsteri. 
  187 
  

  

  m. 
  ob. 
  Medulla 
  oblongata. 
  s. 
  g. 
  c. 
  Substantia 
  gelatinosa 
  cen- 
  

  

  m. 
  th. 
  Mesethinoid 
  cartilage. 
  trails. 
  

  

  n. 
  2. 
  Optic 
  nerves. 
  sp. 
  gn. 
  Spinal 
  ganglion. 
  

  

  n. 
  3. 
  Oculomotor 
  nerves. 
  sp. 
  n. 
  Spinal 
  nerve. 
  

  

  ?i. 
  4. 
  Trochleares 
  nerves. 
  s. 
  r. 
  Siuus 
  rbomboidalis 
  or 
  fourth 
  

  

  n. 
  5. 
  Trifacial 
  nerves. 
  ventricle. 
  

  

  n. 
  7. 
  Facial 
  nerves. 
  t. 
  c. 
  op. 
  Transverse 
  commissure 
  of 
  

  

  n. 
  8. 
  Acusticus. 
  the 
  optic 
  lobe. 
  

  

  n. 
  9. 
  Glossopharyngeal. 
  th. 
  Thalamencephalon. 
  

  

  n. 
  10. 
  Vagus. 
  t. 
  i. 
  Tuberculum 
  intermedium. 
  

  

  0. 
  Ophthalmic 
  nerve. 
  t. 
  tri. 
  Tuberosity 
  of 
  the 
  trifacial. 
  

  

  01. 
  o. 
  Olfactory 
  sac. 
  t. 
  v. 
  Tuberosity 
  of 
  the 
  vagus. 
  

   op. 
  1. 
  Optic 
  lobe. 
  v. 
  c. 
  Ventriculus 
  communis. 
  

  

  op. 
  tr. 
  Optic 
  tract. 
  v. 
  h. 
  g. 
  Ventral 
  horn 
  of 
  grey 
  sub- 
  

  

  pa. 
  Palatine 
  nerve. 
  stance. 
  

  

  p.c. 
  Posterior 
  commissure. 
  v. 
  I.e. 
  Ventral 
  longitudinal 
  column. 
  

  

  pi. 
  Hypophysis 
  cerebri. 
  r. 
  r. 
  Ventral 
  roots 
  of 
  the 
  spinal 
  

  

  p. 
  m. 
  Pia 
  mater. 
  nerves. 
  

  

  p.p. 
  Process 
  of 
  the 
  pterygopalatine 
  v.t.c. 
  Ventral 
  transverse 
  commis- 
  

  

  bone. 
  sure. 
  

  

  pr. 
  Prosencephalon. 
  v. 
  th. 
  Third 
  ventricle. 
  

  

  r. 
  c. 
  Restiform 
  column. 
  v. 
  v. 
  Valve 
  of 
  Vieussens, 
  valvula 
  

   rh. 
  Rhinencephalon. 
  cerebelli, 
  or 
  anterior 
  medullary 
  

  

  r. 
  i. 
  Ramus 
  intestinalis. 
  velum. 
  

  

  r. 
  I. 
  Ramus 
  lateralis. 
  

  

  Fig. 
  1. 
  Dorsal 
  view 
  of 
  the 
  brain, 
  with 
  the 
  distribution 
  of 
  the 
  nerves, 
  as 
  

   far 
  as 
  can 
  be 
  seen 
  on 
  that 
  aspect 
  ; 
  right 
  side 
  shows 
  the 
  super- 
  

   ficial 
  nerves, 
  left 
  side 
  the 
  deeper 
  nerves, 
  natural 
  size. 
  

  

  Fig. 
  2. 
  Side 
  view 
  of 
  the 
  brain, 
  with 
  part 
  of 
  the 
  skull 
  in 
  outline, 
  nat. 
  size. 
  

  

  Fig. 
  3. 
  View 
  of 
  the 
  brain 
  from 
  below, 
  nat. 
  size. 
  

  

  [Transverse 
  sections 
  arranged 
  in 
  consecutive 
  order 
  from 
  before 
  

   backward.] 
  

  

  Fig. 
  4. 
  Transverse 
  section 
  through 
  the 
  prosencephalon 
  immediately 
  be- 
  

   hind 
  the 
  point 
  where 
  the 
  two 
  sides 
  become 
  entirely 
  separated 
  

   from 
  each 
  other, 
  X 
  6|. 
  

  

  Fig. 
  5. 
  Transverse 
  section 
  through 
  the 
  anterior 
  part 
  of 
  the 
  thalamen- 
  

   cephalon 
  with 
  the 
  chiasma 
  of 
  the 
  optic 
  nerves 
  and 
  the 
  crura 
  

   cerebri, 
  X 
  8|. 
  

  

  Fig. 
  6. 
  Transverse 
  section 
  through 
  the 
  posterior 
  end 
  of 
  the 
  thalamen- 
  

   cephalon 
  and 
  the 
  infundibulum, 
  X 
  8^. 
  

  

  Fig. 
  7. 
  Transverse 
  section 
  through 
  the 
  anterior 
  end 
  of 
  the 
  aqueduct 
  of 
  

   Sylvius, 
  at 
  the 
  point 
  where 
  the 
  infundibulum 
  becomes 
  clear 
  of 
  

   the 
  inferior 
  surface 
  of 
  the 
  brain, 
  x 
  8|. 
  

  

  Fig. 
  8. 
  Transverse 
  section 
  through 
  the 
  mesencephalon 
  at 
  the 
  point 
  where 
  

   the 
  oculomotores 
  emerge, 
  x 
  14. 
  

  

  Fig. 
  9. 
  Transverse 
  section 
  through 
  the 
  valve 
  of 
  Vieussens, 
  showing 
  de- 
  

   cussation 
  of 
  the 
  fourth 
  nerve 
  and 
  posterior 
  edge 
  of 
  the 
  optic 
  

   lobe, 
  x 
  14. 
  

  

  Fig. 
  10. 
  Transverse 
  section 
  through 
  the 
  cerebellum, 
  x 
  14. 
  

  

  Fig. 
  11. 
  Transverse 
  section 
  through 
  the 
  origin 
  of 
  the 
  anterior 
  root 
  of 
  the 
  

   trifacial 
  nerve, 
  X 
  14. 
  

  

  Fig. 
  12. 
  Transverse 
  section 
  through 
  the 
  sinus 
  rbomboidalis 
  at 
  the 
  point 
  

   of 
  apparent 
  origin 
  of 
  the 
  posterior 
  root 
  of 
  the 
  trifacial, 
  facial, 
  

   and 
  acusticus, 
  X 
  14. 
  

  

  